CA1257859A - Self-supporting structures containing immobilized inorganic sorbent particles and method for forming same - Google Patents
Self-supporting structures containing immobilized inorganic sorbent particles and method for forming sameInfo
- Publication number
- CA1257859A CA1257859A CA000488218A CA488218A CA1257859A CA 1257859 A CA1257859 A CA 1257859A CA 000488218 A CA000488218 A CA 000488218A CA 488218 A CA488218 A CA 488218A CA 1257859 A CA1257859 A CA 1257859A
- Authority
- CA
- Canada
- Prior art keywords
- sorbent
- particles
- polymeric
- binding material
- self
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/2803—Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28004—Sorbent size or size distribution, e.g. particle size
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28026—Particles within, immobilised, dispersed, entrapped in or on a matrix, e.g. a resin
Abstract
Abstract:
A self-supporting structure comprising an inor-ganic sorbent and method for preparing is described in which the self-supporting structure is substan-tially free of sorbent fines and the sorption char-acteristics of the sorbent particles is retained.
The process for immobilizing the sorbent particles in the self-supporting structure comprises the steps of:
(a) preheating inorganic sorbent particles to an elevated temperature;
(b) mixing the sorbent particles with particles of a polymeric binding material to form a mixture comprising the particles of polymeric binding mater-ial adhered to the sorbent particles; and (c) heating the mixture to about the solid-liquid transition temperature of the polymeric bind-ing material with or without pressure to form a structure which upon cooling is self supporting.
A self-supporting structure comprising an inor-ganic sorbent and method for preparing is described in which the self-supporting structure is substan-tially free of sorbent fines and the sorption char-acteristics of the sorbent particles is retained.
The process for immobilizing the sorbent particles in the self-supporting structure comprises the steps of:
(a) preheating inorganic sorbent particles to an elevated temperature;
(b) mixing the sorbent particles with particles of a polymeric binding material to form a mixture comprising the particles of polymeric binding mater-ial adhered to the sorbent particles; and (c) heating the mixture to about the solid-liquid transition temperature of the polymeric bind-ing material with or without pressure to form a structure which upon cooling is self supporting.
Description
1~:57859 SELF-SUPPORTING STRUCTURES CONTAINING
IMMOBILIZED INORGANIC SOR~ENT PARTICLES
AND METHOD FOR FOR~ING SAME
The present invention relates to structures in which inorganic sorbent particles are immobilized with a polymeric binding agent and to a process for 15 forming the structures. More particularly, the pres-ent invention relates to a process for forming a self-supporting structure in which inorganic sorbent particles are immobilized with a polymeric binding material while maintaining the sorption chaxacteris-20 tics of the inorganic particles.
In a variety of commercial and industrial set-tings, it is necessary to remove one or more compon-ents from a fluid, i.e., a gas or a liquid, before the fluid can be used for a particular purpose. ~or 25 example, before contaminated water can be drunk, any chemical contaminants must be removed. Likewise, before compressed air can be use,~, for example to drive power tools, any water or water vapor must be removed or the tools will rust.
Many types of devices are available to remo~ve one or more components from a fluid. One particular-ly effective class of devices characteristically comprises an apparatus which directs a flow of the fluid through a sorbent material, i.e., a material 35which absorbs or adsorbs certain components. This $~
.~
~ 25 7 8S9 sorbent material is ty~ically in the form of a bed of sor~ent particles which may ~e either loosely loaded or loaded under compression into a vertically orient-ed vessel. During a sorbing phase, the fluid con-5 taining the components is pumped at a certain pres-sure into either the top or the bottom of the vessel and then passed through the sorbent particle bed where the component is sorbed by the sorbent mater-ial. The fluid, now free of the component, is then 10 removed from the other end of the vessel.
To extend the useful life of these sorbing apparatus, the sorbent bed is periodically regen-erated, i.e., stripped of the component it has ab-sorbed or adsorbed from the fluid. During a regen-15 erating phase, the vessel is typically depressurized.Then, a heated and/or component-free fluid is flushed through ~he sorbent bed, purging the component from the sorbent particles. This purging fluid, now con-taining much of the component previously sorbed by 20 the sorbent bed, is then exhausted. Once the sorbent bed is sufficiently free of the component, the vessel is repressurized and the fluid containing the com-ponent is again pumped through the vessel. The re-generated sorbent bed then continues absorbing or 25 adsorbing the component from the fluid.
As effective as these apparatus are, they nev-ertheless have several undesirable characteristics.
For example, they frequently generate significant quantities of sorbent dust, i.e., small fragments of 30 the sorbent particles. Sorbent dust, which is ex-tremely abrasive, can flow with the fluid through the end of the vessel. To withstand the destructive effect of this abrasive dust, any downstream pipes and valves are typically made of a heavier gauge than 35 would otherwise be necessary and/or are specially ~257B5 designed to accomodate the severe conditions. Such pipes and valves significantly increase the weight and cost of the apparatus. These sorbing apparatus typically include a sorbent dust filter downstream 5 from the so~bent bed to prevent migration of the sorbent dust. While the sorbent dust filter may collect much of the dust, it nonetheless adds to the mechanical complexity of the apparatus. It also increases both the maintenance and operational costs 10 since the filter must be periodically cleaned or replaced -Sorbent dust may be generated in a variety of ways. For example, when loading the sorbent par-ticles in~o the vessel, the particles can abrade 15 against one another, generating sorbent dust. They can also abrade against one another whenever the sorbent bed is jarred, e.g., when the sorbing appar-atus is transported, or when it must be mounted where it is subjected to vibration, e.g., on board a ship.
20 Further, once loaded, the sorbent particles at the bottom of the bed bear the weight of the entire sor-bent bed and may be crushed into sorbent dust by the load. To avoid fragmenting or crushing sorbent par-ticles, these sorbing apparatus characteristically 25 use extremely hard particles which significantly limits the type of sorbent that can be used.
Sorbent dust may also be generated if the sor-bent bed becomes fluidized, i.e., if the particles of sorbent are moved by the fluid passing through the 3~ bed. The moving sorbent particles may collide with and/or abrade against one another, generating the dust. To avoid fluidization in the sorbing phase, available sorbing apparatus maintain the velocity of the fluid at a very low level which, for some appli-35 cations, significantly limits the amount of fluid ~s~s~
that can be processed in a given amount of time. To avoid fluidization during the regenerating phase, the sorbing apparatus typically not only maîntain the velocity of the purging fluid at a very low level but 5 also depressurize and repressurize the vessel rela-tively slowly. This significantly increases the amount of time required for regeneration. Known sorbing apparatus also avoid fluidization by com-pressing the sorbent bed, e.g., by using spring-10 loaded mechanisms which bear against the top of thebed. Not only are these mechanisms frequently heavy and expensive but they further add to the load that the particles at the bottom of the bed must bear.
Another undesirable characteristic of known 15 sorbing apparatus is that the sorbent bed, although initially loaded evenly, may develop channels since the sorbent particles may settle within the bed due to vibration or shock. These channels allow the Eluid to bypass the sorbent particles and decrease 20 the effectiveness of the sorbent bed in removing the component from the fluid. To minimize channelling, the vessels of known sorbing apparatus are generally oriented vertically. Vertical vessels, however, require supports, such as legs, to keep them upright.
25 These supports, again, significantly increase both the weight and cost of the apparatus. Further, it is frequently desirable that these devices be portable.
Since the center of gravity of a vertical vessel is much higher than that of a horizontal, the apparatus 30 is more likely to tip over when moved.
The development of an immobilized sorbent and a method of preparing such a sorbent which could be used in such systems would serve to alleviate the problems and difficulties discussea above.
~2~i785~3 According to the present invention there is provided a process for immobilizing inorganic sorbent particles with a polymeric binding material and form-ing a self-supporting structure therefrom, thereby 5 substantially eliminating the formation of sorbent fines while retaining the sorption characteristics of the inorganic sorbent particles, comprising the steps of: (a) preheating the inorganic sorbent particles to , an elevated temperature, (b) mixing the heated sor~
10 bent particles with particles of the polymeric bind-ing material to form a mixture comprising the par-ticles of polymeric binding material adhered to the sorbent particles, and (c) heating the mixture to about the solid-liquid transition temperature of said 15 polymeric binding material with or without pressure to form a structure which upon cooling is self-sup-porting.
According to the present invention there is also provided an improvement in a process for immo-20 bilizing inorganic sorbent particles in a polymericbinding material, the improvement comprising heating the sorbent particles prior to mixing them with the polymeric binding material.
According to the present invention there is 25 further provided a self-supporting, immobilized inor-ganic sorbent structure substantially free of mobile sorbent fines, having a low pressure drop and high sorptive capacity comprising inorganic sorbent par-ticles, a major portion of which has particle sizes 30in the range of from about 1 to about 10 millimeters, and about 1 to about 7 percent by weight of a poly-meric binding material, the percentage of the poly-meric binding material being based on the weight of the structure.
.Still further according to the present inven-25'~859 tion there is provided a self-supporting, immobilized inorganic soxbent structure substantially free of mobile inorganic sorbent fines having a low pressure drop and high sorptive capacity comprising inorganic 5 sorbent particles and about l to about 7 percent by weight of a polymeric binding material, the percent-age of the polymeric binding material being based on the weight of the structure and the major portion of the particles thereof having particle sizes in the 10 range of from about 8 to about 100 micrometers.
Thus, the present invention provides structures and methods for producing such structures in which inorganic sorbent particles are immobilized within the structures and any tendency to form fines (fine 15 particles of sorbent which inherently have a greater tendency to migrate), is substantially reduced or even virtually eliminated. The present invention is directed to self-supporting structures in which sor-bent inorganic particles, including any sorbent fines 20 present, are immobilized with a polymeric binding material.
The structures of the present invention sub-stantially retain the inherent sorption character-istics of the sorbent particles with minimal increase 25 in pressure drop across the structures. as compared with comparably sized beds of non-immobilized sorbent particles of the same type. The self-supporting structures also provide resistance to compressive or deformation forces (which resistance is lacking in 30 non-immobilized sorbent particles~ which allows the structures to be more easily handled and transported without substantial loss of structural integrity and without the production of fines due to particle-to-particle abrasion. Further, the requirement that the 35 sorbent be hard, i.e., resistant to attrition, is ~257859 negated since the sorbent in the structure of the present invention is held securely by the polymeric binding material, thereby substantially eliminating relative movement of the sorbent particles with re-5 sultant attrition and the production of fines.
Stated in the alternative, because the sorbent par-ticles are immobilized, a wide variety of sorbents (including softer ones than those previously con-sidered satisfactory) may be used. Thus, the self-10 supporting immobilized sorbent structures in accord-ance with the present invention are suitable for treating a variety of gaseous and liquid materials.
Additionally, the sorbent structures in ac-cordance with this invention may in general be de-15 sorbed or regenerated, making the structures adapt-able for use in regenerable systems. The present invention then is directed to a process for immo-bilizing sorbent particles and forming a self-sup-porting structure therefrom having the properties 20 described above, namely, the substantial elimination of mobility and loss of sorbent, as well as preven-tion of the formation of sorbent fines while pro-viding a structure with a relatively low pressure drop across the structure and one that substantially 25 retains the sorption characteristics of the sorbent particles themselves.
The sorbents which may be used in this inven-tion are inorganic particulate materials, particu-larly inorganic oxides of aluminum, silicon and /
/ /
/
~ ~2S78~9 ~
magnesium such as alumina, silica, magnesia, molec-ular sieves, zeolites, silica gel, and activated alumina. These materials are generally produced by thermal cycling of gels of the particular inorganic 5 oxide.
In general, a major portion of the sorbent should have particle sizes in the range of about 1 to about 10 millimeters. With proper classification of the sorbent, the major portion generally cc:stitutes 10 95 to 99.5 percent of the material. Most preferably, the average particle size of the sorbent particles is about 2 to about s millimeters. with finer particle size sorbent, relatively more binder is desirable because of greater external surface area available 15 for bonding. Conversely, as the average particle size increases, a lesser amount of the binder is preferably used. However, there is a general corre-lation between the amount of binder used and the amount of fines which can be bound by the structure, 20 i.e., reducing the amount of binder may reduce the quantity of fines which may be immobilized.
The specific surface area of the sorbent will generally be in the range of from about 200 to about 1,000 m2/gram, more preferably from about 200 to 25 about 500 m2/gram. The bulk density of the sorbent is generally in the range of from about 0.5 to about 1.3 g/cc. When pressure is applied in the compres-sive step, an increase in the bulk density, commonly about 10%, will typically occur.
A preferred form of alumina for use in prepar-ing structures in accordance with the present in-vention is an activated alumina available from Rhone-Poulenc Corporation, under the designation DE-4.
This product is spherical in shape and a major por-35 tion of the particles have diameters in the range of ~ 78S9 g from 2 to 5 millimeters. It has a surface area of about 317 m2/gm. For the preferred activated alumina sorbents, ~he surface areas will generally lie in the range of from about 200 to about 500 m2/gm.
S Preferably, the sorbent particles are sub-stantially spherical in shape to maximize the surface area of the sorbent and so that the resulting immo-bilized sorbent will combine a relatively small pres-sure drop associated with a high adsorptive ability.
10 However, because of their spherical shape, the sor-bent particles will not readily adhere to the poly-meric binding material. Accordingly, by heating the sorbent particles prior to mixing with the binding material, the binding material particles become tacky 15 upon mixing and adhere to the sorbent particles.
Polymeric Binding Material:
As used herein, "polymerlc binding material" or 20 "binder" refers to either a thermoplastic or thermo-setting polymeric material, preferably synthetic, which is capable of being shaped under the process conditions of the present invention.
The term "thermoplastic material" describes the 25 preferred polymeric binding material of the present invention and generally refers to any polymeric mat-erial having thermoplastic properties and may include any synthetic or semi-synthetic condensation or poly-merization product. Preferably, the thermoplastic 30 material is a homopolymer or copolymer of a polyole-fin. Most preferable are polyethylene and polypro-pylene, the former being particularly preferred.
Other thermoplastic materials include poly-styrene, polycarbonates, polyurethanes, phenoxy 35 resins, vinyl resins derived from monomers such as ~257~59 -].o-vinyl chloride, vinyl acetate, vinylidine chloride, etcetera, including polyvinyl chloride, copolymers of vinyl chloride with one or more of acrylonitrile, methacrylonitrile, vinylidine chloride, alkyl acryl~
5 ate, alkyl methacrylate, alkyl maleate, alkyl fumar-ate, etcetera.
In some instances, to provide creep resistance, a thermosetting material may be preferred as the polymeric binding material. Suitable for this use 10 are the type of cross-linked polyethylenes used as cable coatings, such as materials formed from blends of polyethylene with peroxide cross-linking agents, such as, for example, benzoyl or dicumyl peroxide present in catalytic amounts. Other examples include 15 those materials in ~hich a prepolymer is reacted with a cross-linking agent to form the product and in-cludes polyurethanes of the type in which a "blocked"
diisocyanate is reacted initially with a difunctional compound, such as a diol, to ~orm the prepolymer 20 which in turn is reacted with a trifunctional com-pound, such as a triol, to form, at the appropriate temperature, the cross-linked polymer. These ther-mosetting mate~ials, which generally cross-link at temperatures between 100-200 degrees C, exhibit pro-25 perties similar to the preferred crystalline thermo-plastic materials discussed below.
The selection of polymeric binding material depends to some extent on the properties sought in the self supporting structure which is formed in part 30 from the binding material. That is, some of the mechanical properties of the immobilized sorbent structure are determined by the physical properties of the binding material. If, for instance, a struc-ture which flexes or which resists fracturing is 35 desired, a thermoplastic powder should be used which ~L2578S9 is not fully crystalline or below its glass trans-ition temperature at the temperature at which the article i5 used. Conversely, a rigid structure re-quires a more crystalline thermoplastic or thermo-setting material.
A requirement of the material selected as the polymeric binding material for use in the present invention is that it have a sufficiently high vis-cosity at the processing temperature so as not to flow and reduce the porosity of the sorbent by "blinding", as discussed below. As also described below, the heating step is conducted in such a manner as to cause the polymeric binding material to begin to soften so that the binder particles lose their original shape and become slightly tacky. The mater-ial should not, however, have a viscosity at the processing temperature such that it flows or blinding may result.
A major portion of the particles of the poly-meric bindiny material should have average particlesizes in the range of about 8 to about 100 micro-meters. When the particle sizes are significantly larger than the upper limit of this range, the powder demonstrates a tendency to settle and a higher weight percentage is required. This may also result, in some instances, in blinding, blinding referring to the tendency for the macropores of the sorbent par-ticle to be covered over with the binding material thereby blocking them and preventing access to the internal micropores of the particle. If binder par-ticle sizes significantly smaller are used, there is also some tendency for blinding to occur.
When thermoplastic materials are used in the present invention, particularly preferred are low density polyethylene powders such as those available ~:2578~9 commercially frolTl USI Cnelllica1s under the trademarks Microthene FN500, FN510 and F~524. These powdered polyethylene powders differ somewl-lat from one another in density and Vicat softening point. Microthene FN500 is somewhat crystalline and has a Vicat softening point of about 195 degrees Fahrerlheit. This material provides the finished structure with substan-tial rigidity.
In addition, wherl a somewhat more flexib]e structure is desired, up to 10 percent of a second ethylenically unsaturated 0 Illaterial, such as vinyl acetate, may be copolymerized with the ethylene -to provide an amorphous thermoplastic binding material.
copolymer oE -this type exhibits less of a tendency to b]ind and also imparts some energy or shock absorbency properties to the immobilized sorbent s-tructure, thereby reducirlg the tendency of the structure to fracture when handled with less caution than -that required by some of the struc-ture using more crystalline homopolymers. A suitable rnaterial of this type comprising 9 percent vinyl acetate copolymerized with polyethylene is avail-able from USI Chemicals under the trademark Microthene FN532.
The binder is present suitably in an amount of about 1 to about 7, preferably about 2 -to about 5, percent by weight, all percen-tages based on the weight of the to-tal mixture comprising binder, sorbent particles and, preferably, a mixiny aid.
~ n anti-agglorneratirlg agen-t or mixing aid, such as fumed silica, is preferably added to the binder in order to inhibit adhesion between particles of the polymeric binding material. Usually, not more than 0.5% by weight of the mixing aid should be used (based on the total weight of the binder and the mixing aid).
~ 57~3S~
Self-Supporting Immobilized Sorbent Structure:
.
~ o form the self-supporting immobilized sorbent structure of the present invention, sorbent particles 5 are preheated and then mixed wi~h an appropriate amount, as indicated above, of polymeric binding material in any suitable manner. When contact is made between a binding material particle and a sor-bent particle, some heat will he transferred from the 10 preheated sorbent particle to the polymeric binder material particle, rendering the polymeric binder material particle tacky, so that the binder material particle will adhere to the sorbent particle. It is important that the temperature to which the sorbent 15 particles are preheated does not greatly exceed the temperature at which the binding material part-cles become softened and take on a semi-liquid consis-tency, i.e., the solid-liquid transition temperature.
The mixture is then allowed to cool while it is 20 mixed so that the binding material particles will become less tacky and will not adhere to one another (will be free flowing). However, the adhesion be-tween particles of polymeric binding material and sorbent material will remain substantially unaffected 25 by the decrease in temperature. An anti-agglomer-ating agent or mixing aid, such as fumed silica, may be combined with the binder prior to combining the binder with the sorbent to further inhibit adhesion between binding material particles.
The resulting dispersion will remain substan-tially uniform, since substantially all of the bind-ing material particles will be adhered to a sorbent particle, and therefore, even though the binding material particles are generally smaller than the 35 sorbent particles, dlJe to their adhesion to the sor--~ ~257~5~3 bent particles, they will not fall to the bottom of the mixing vessel.
It is usually unnecessary to use any particular precautions or undue care to avoid crushing the sor-S bent which would increase the fines content, duringblending, since the polymeric binding agent is cap-able of retaininq the fines. Care should be em-ployed, however, when the sorbent particles already contain a signi~icant amount of fines.
Once mixing has been completed and a substan-tially uniform mixture has been obtained, the mixture is preferably transferred to a mold having the par-ticular volume and shape desired. Alternatively, the vessel in which the components are mixed can also 15 serve as the mold.
Heat is then applied to the contents of the mold to provide an immobilized sorbent structure.
Pressure may be applied while the mixture is at an elevated tempecature to impart greater compressive 20 strength to the structure. To immobilize the sorbent particles, particularly the fines, the particles should be effectively secured or trapped by the bind-er. Effective trapping of fines occurs (with the consequent increase in strength of the structure with 25 the minimal reduction of sorptive properties) and the minimal increase in pressure drop results when the sorbent particles and fines are uniformly distributed in the self-supporting structure. This does not mean that each sorbent particle is completely enveloped in 30 the polymeric binding material. On the contrary, it is preferred that each particle merely be held in place by the polymeric binding material. This may be accomplished by raising the temperature of the mix-ture to about the solid-liquid transition temperature 35 of the binder to produce a suitable consistency in the polymeric binding material. Use of the proper temperature for a particular polymeric binding mater-ial causes that material to be softened and form a semi-solid o{ semi-liquid consistency. That is, the 5 material is softened to the extent that no well de-fined binder particles exist which have the physical attributes of a solid yet the material does not flow as does a liquid. At this temperature or stage, termed herein as the "solid-liquid transition stage", ~10 which is about 50 to about 90 degrees Fahrenheit above the Vicat softening point, the polymeric bind-ing material exhibits an increased tackiness. This tackiness, probably resulting from increased mobility of the molecular chains of the molecules, provides improved interparticle adhesion. The solid-liquid transition stage i5 not to be confused with a melting point in which solid and liquid phases exist in dy-namic equilibrium with one another. At the solid-liquid transition stage, the polymeric binding mat-20 erial may be thought to be in a hybrid state betweensolid and liquid states. When at this stage, the mixture of polymeric binding material and sorbent - particles may be compressed sufficiently by appli-cation of pressure to increase the number of contact 25 points between adjacent particles and increase inter-particle bonding, providing thereby increased com-pressive strength with retention of sorptive prop-erties. The solid-liquid transition stage for a polymeric binding material is not as sharply defined 30 as is the melting point of a pure crystalline mater-ial, and, in some instances, the temperature range of this stage is somewhat broad~ However, it is still undesirable to use temperatures in the present proc-ess which are much above the temperature range of the 35 solid-liquid transition stage since the polymeric ~ ~2S7859 -16~
binding material then exhibits the characteristics of a liquid in that it tends to readily flow. This is to be avoided since blinding of the pores of the sorbent may occur and formation of a mass or block of 5 coated sorbent particles in which the sorption and gas permeability characteristics have been reduced or lost may also result.
The heat required to raise the temperature of the mixture of polymeric binding material and sorbent 10 to the temperature at which the polymeric binding material is at its solid-liquid transition stage may ¦ be supplied by any conventional equipment, such as, for example, a forced hot air or convection oven, a heat jacketed mold, an infrared heater, or a heated 15 roller or rollers. Depending on the apparatus used for heating the sample and the volume of the mold, heating to the solid-liquid transition stage may take from about 10 minutes to an hour or more.
The compressive or crush strength of the self-20 supporting structures increases as the magnitude ofthe pressure applied during the forming step at the solid-liquid transition stage is increased. Like-wise, the pressure drop across the self-supporting structure increases as the magrlitude of pressure 25 applied to the sorbent/polymeric binding material mixture during formation of the structure is in-creased.
Pressure may be supplied to the mold by place-ment between two pressure rollers (calendering), by 30 appropriate placement of a weight, by hydraulic means, such as by use of a piston~ or by any other device and method known for application of pressure to a mold.
While the compressive pressure may be applied 35 during or after elevation of the temperature to the ~ ~ ~,5785~ 7 solid-liquid transition stage, it is preferred to raise the temperature to, or very close to, the sol-id-liquid transition stage where the polymeric bind-ing material is soft and about to flow prior to ap-5 plication of pressure. Once the mixture is raised tothe temperature of the solid-liquid transition stage and thermal equilibrium is established, pressure is typically applied for from about 1 to about 10 min-utes. The temperature of the mixture must be held 10 within the range of the solid-liquid transition stage of the polymeric binding material for about the first minute during which the pressure is applied.
Pressures in the range of up to the crush strength of the sorbent, which is generally from 15 about 100 to about 200 psi, may be used, albeit, from a practical perspective, from about 0.3 to about 50 psi are preferred, more preferably from about 0.3 to about 20. That is, generally the compressive strength of the self-supporting immobilized structure is di-20 rectly related to the pressure applied at the solid-liquid transition stage. For most purposes, very high compressive strengths are not required. Thus, by using lower pressures during the process, simpler equipment may be employed and a self-supporting struc-25 ture having adequate strength, particularly compres-sive or crush strength, to permit ease of handling and transport, as well as minimum pressure drop across the structure and maximum sorption character-istics, is achieved while substantially eliminating 30 the formation of fines and retaining or immobilizing previously existing fines.
The resulting structure is capable of being desorbed or regenerated and therefore the sorptive capability of the sorbent can be reused, with the 35 chance of the sorbent escaping being greatly reduced.
~ ~257~5~ ~
While the invention is susceptible to various modifications and alternative forms, certain specific embodiments thereof are described in the examples set forth below. It should be understood, however, that 5 these examples are not intended to limit the inven~
tion to the particular forms disclosed but, on the contrary, the intention is to cover all modifica-tions, equivalents and alternatives falling within the spirit and scope of the invention.
~ 1 0 Examp_es:
General Method For Preparation Of Examples 1 To 6:
.
Examples 1 to 6 were prepared by essentially the same procedure as set out below. Specific di~-ferences in conditions or materials are noted below.
1000 gram portions of Rhone-Poulenc DE-4 ac- `
20 tivated alumina beads were weighed and placed in 2 liter glass jars. The activated alumina was gener-ally of diameter from about 2 to about 5 millimeters.
Each open glass jar was then placed in an oven, for about one hour, preheated to about 270 degrees Fahr-25 enheit which temperature is approximately equal tothe solid-liquid transition temperature of polyethyl-ene, the polymeric binder powder being used.
Separate portions of Microthene FN500 and FN510 polyethylene powder from U. S. I Chemicals (Micro-30 thene FN500 and FN510 are both low density polyethyl-ene; FN510 has a slightly higher Vicat softening point than FN500), were then mixed with fumed silica ~ 4~ k- ~f (Sipernat 17-fr~m Degussa Corporation), which acts as an anti-agglomeration agent for the polyethylene so 35 that the resulting mixture was 0.5 percent by total 7 ~9 weight fumed silica. The homogenously blended mix-ture was then weighed into appropriate pcrtions to be added to the pre-heated activated alumina.
The glass jars were then removed from the oven 5 and the contents of each jar of hot alumina were transferred to separate 4 liter mixing vessels. Ap-propriate pre-weighed portions of Microthene/fumed silica were immediately blended into each vessel containing the hot alumina particles. Stirring was 1~ continued until the mix cooled to about 70 degrees Centigrade to ensure that the polyethylene powder had adhered to the alumina.
In order to mold the above material, a cylin-drical mold of the desired dimensions was filled with 15 the alumina/polyethylene/silica mixture. The mold was restrained on the top and bottom by perforated metal plates that were placed within the cylinder.
The assembly was then placed in an oven pre-heated to a molding temperature at about the solid-liquid tran-~0 sition temperature of the polyethylene. After re-maining at this temperature for about one hour, or until a uniform temperature was attained, the mold was removed from the oven and placed on a hydraulic press. Pressure was then applied for about one min-25 ute. The composition, molding temperature and pres-sure applied in each of the examples are shown in Table 1. The cooled immobilized activated alumina structures produced by the examples were found to be self supporting.
~257~5~3 ~
--,.o--Example Percentage of Molding Compressive Polyethylene Temperature Pressure based on weight (Degrees of Polyethylene/ Fahrenheit) ~lumina/Fumed Silica Mixture (FN #) 1 ~.0 (500) 260 10 psi
IMMOBILIZED INORGANIC SOR~ENT PARTICLES
AND METHOD FOR FOR~ING SAME
The present invention relates to structures in which inorganic sorbent particles are immobilized with a polymeric binding agent and to a process for 15 forming the structures. More particularly, the pres-ent invention relates to a process for forming a self-supporting structure in which inorganic sorbent particles are immobilized with a polymeric binding material while maintaining the sorption chaxacteris-20 tics of the inorganic particles.
In a variety of commercial and industrial set-tings, it is necessary to remove one or more compon-ents from a fluid, i.e., a gas or a liquid, before the fluid can be used for a particular purpose. ~or 25 example, before contaminated water can be drunk, any chemical contaminants must be removed. Likewise, before compressed air can be use,~, for example to drive power tools, any water or water vapor must be removed or the tools will rust.
Many types of devices are available to remo~ve one or more components from a fluid. One particular-ly effective class of devices characteristically comprises an apparatus which directs a flow of the fluid through a sorbent material, i.e., a material 35which absorbs or adsorbs certain components. This $~
.~
~ 25 7 8S9 sorbent material is ty~ically in the form of a bed of sor~ent particles which may ~e either loosely loaded or loaded under compression into a vertically orient-ed vessel. During a sorbing phase, the fluid con-5 taining the components is pumped at a certain pres-sure into either the top or the bottom of the vessel and then passed through the sorbent particle bed where the component is sorbed by the sorbent mater-ial. The fluid, now free of the component, is then 10 removed from the other end of the vessel.
To extend the useful life of these sorbing apparatus, the sorbent bed is periodically regen-erated, i.e., stripped of the component it has ab-sorbed or adsorbed from the fluid. During a regen-15 erating phase, the vessel is typically depressurized.Then, a heated and/or component-free fluid is flushed through ~he sorbent bed, purging the component from the sorbent particles. This purging fluid, now con-taining much of the component previously sorbed by 20 the sorbent bed, is then exhausted. Once the sorbent bed is sufficiently free of the component, the vessel is repressurized and the fluid containing the com-ponent is again pumped through the vessel. The re-generated sorbent bed then continues absorbing or 25 adsorbing the component from the fluid.
As effective as these apparatus are, they nev-ertheless have several undesirable characteristics.
For example, they frequently generate significant quantities of sorbent dust, i.e., small fragments of 30 the sorbent particles. Sorbent dust, which is ex-tremely abrasive, can flow with the fluid through the end of the vessel. To withstand the destructive effect of this abrasive dust, any downstream pipes and valves are typically made of a heavier gauge than 35 would otherwise be necessary and/or are specially ~257B5 designed to accomodate the severe conditions. Such pipes and valves significantly increase the weight and cost of the apparatus. These sorbing apparatus typically include a sorbent dust filter downstream 5 from the so~bent bed to prevent migration of the sorbent dust. While the sorbent dust filter may collect much of the dust, it nonetheless adds to the mechanical complexity of the apparatus. It also increases both the maintenance and operational costs 10 since the filter must be periodically cleaned or replaced -Sorbent dust may be generated in a variety of ways. For example, when loading the sorbent par-ticles in~o the vessel, the particles can abrade 15 against one another, generating sorbent dust. They can also abrade against one another whenever the sorbent bed is jarred, e.g., when the sorbing appar-atus is transported, or when it must be mounted where it is subjected to vibration, e.g., on board a ship.
20 Further, once loaded, the sorbent particles at the bottom of the bed bear the weight of the entire sor-bent bed and may be crushed into sorbent dust by the load. To avoid fragmenting or crushing sorbent par-ticles, these sorbing apparatus characteristically 25 use extremely hard particles which significantly limits the type of sorbent that can be used.
Sorbent dust may also be generated if the sor-bent bed becomes fluidized, i.e., if the particles of sorbent are moved by the fluid passing through the 3~ bed. The moving sorbent particles may collide with and/or abrade against one another, generating the dust. To avoid fluidization in the sorbing phase, available sorbing apparatus maintain the velocity of the fluid at a very low level which, for some appli-35 cations, significantly limits the amount of fluid ~s~s~
that can be processed in a given amount of time. To avoid fluidization during the regenerating phase, the sorbing apparatus typically not only maîntain the velocity of the purging fluid at a very low level but 5 also depressurize and repressurize the vessel rela-tively slowly. This significantly increases the amount of time required for regeneration. Known sorbing apparatus also avoid fluidization by com-pressing the sorbent bed, e.g., by using spring-10 loaded mechanisms which bear against the top of thebed. Not only are these mechanisms frequently heavy and expensive but they further add to the load that the particles at the bottom of the bed must bear.
Another undesirable characteristic of known 15 sorbing apparatus is that the sorbent bed, although initially loaded evenly, may develop channels since the sorbent particles may settle within the bed due to vibration or shock. These channels allow the Eluid to bypass the sorbent particles and decrease 20 the effectiveness of the sorbent bed in removing the component from the fluid. To minimize channelling, the vessels of known sorbing apparatus are generally oriented vertically. Vertical vessels, however, require supports, such as legs, to keep them upright.
25 These supports, again, significantly increase both the weight and cost of the apparatus. Further, it is frequently desirable that these devices be portable.
Since the center of gravity of a vertical vessel is much higher than that of a horizontal, the apparatus 30 is more likely to tip over when moved.
The development of an immobilized sorbent and a method of preparing such a sorbent which could be used in such systems would serve to alleviate the problems and difficulties discussea above.
~2~i785~3 According to the present invention there is provided a process for immobilizing inorganic sorbent particles with a polymeric binding material and form-ing a self-supporting structure therefrom, thereby 5 substantially eliminating the formation of sorbent fines while retaining the sorption characteristics of the inorganic sorbent particles, comprising the steps of: (a) preheating the inorganic sorbent particles to , an elevated temperature, (b) mixing the heated sor~
10 bent particles with particles of the polymeric bind-ing material to form a mixture comprising the par-ticles of polymeric binding material adhered to the sorbent particles, and (c) heating the mixture to about the solid-liquid transition temperature of said 15 polymeric binding material with or without pressure to form a structure which upon cooling is self-sup-porting.
According to the present invention there is also provided an improvement in a process for immo-20 bilizing inorganic sorbent particles in a polymericbinding material, the improvement comprising heating the sorbent particles prior to mixing them with the polymeric binding material.
According to the present invention there is 25 further provided a self-supporting, immobilized inor-ganic sorbent structure substantially free of mobile sorbent fines, having a low pressure drop and high sorptive capacity comprising inorganic sorbent par-ticles, a major portion of which has particle sizes 30in the range of from about 1 to about 10 millimeters, and about 1 to about 7 percent by weight of a poly-meric binding material, the percentage of the poly-meric binding material being based on the weight of the structure.
.Still further according to the present inven-25'~859 tion there is provided a self-supporting, immobilized inorganic soxbent structure substantially free of mobile inorganic sorbent fines having a low pressure drop and high sorptive capacity comprising inorganic 5 sorbent particles and about l to about 7 percent by weight of a polymeric binding material, the percent-age of the polymeric binding material being based on the weight of the structure and the major portion of the particles thereof having particle sizes in the 10 range of from about 8 to about 100 micrometers.
Thus, the present invention provides structures and methods for producing such structures in which inorganic sorbent particles are immobilized within the structures and any tendency to form fines (fine 15 particles of sorbent which inherently have a greater tendency to migrate), is substantially reduced or even virtually eliminated. The present invention is directed to self-supporting structures in which sor-bent inorganic particles, including any sorbent fines 20 present, are immobilized with a polymeric binding material.
The structures of the present invention sub-stantially retain the inherent sorption character-istics of the sorbent particles with minimal increase 25 in pressure drop across the structures. as compared with comparably sized beds of non-immobilized sorbent particles of the same type. The self-supporting structures also provide resistance to compressive or deformation forces (which resistance is lacking in 30 non-immobilized sorbent particles~ which allows the structures to be more easily handled and transported without substantial loss of structural integrity and without the production of fines due to particle-to-particle abrasion. Further, the requirement that the 35 sorbent be hard, i.e., resistant to attrition, is ~257859 negated since the sorbent in the structure of the present invention is held securely by the polymeric binding material, thereby substantially eliminating relative movement of the sorbent particles with re-5 sultant attrition and the production of fines.
Stated in the alternative, because the sorbent par-ticles are immobilized, a wide variety of sorbents (including softer ones than those previously con-sidered satisfactory) may be used. Thus, the self-10 supporting immobilized sorbent structures in accord-ance with the present invention are suitable for treating a variety of gaseous and liquid materials.
Additionally, the sorbent structures in ac-cordance with this invention may in general be de-15 sorbed or regenerated, making the structures adapt-able for use in regenerable systems. The present invention then is directed to a process for immo-bilizing sorbent particles and forming a self-sup-porting structure therefrom having the properties 20 described above, namely, the substantial elimination of mobility and loss of sorbent, as well as preven-tion of the formation of sorbent fines while pro-viding a structure with a relatively low pressure drop across the structure and one that substantially 25 retains the sorption characteristics of the sorbent particles themselves.
The sorbents which may be used in this inven-tion are inorganic particulate materials, particu-larly inorganic oxides of aluminum, silicon and /
/ /
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~ ~2S78~9 ~
magnesium such as alumina, silica, magnesia, molec-ular sieves, zeolites, silica gel, and activated alumina. These materials are generally produced by thermal cycling of gels of the particular inorganic 5 oxide.
In general, a major portion of the sorbent should have particle sizes in the range of about 1 to about 10 millimeters. With proper classification of the sorbent, the major portion generally cc:stitutes 10 95 to 99.5 percent of the material. Most preferably, the average particle size of the sorbent particles is about 2 to about s millimeters. with finer particle size sorbent, relatively more binder is desirable because of greater external surface area available 15 for bonding. Conversely, as the average particle size increases, a lesser amount of the binder is preferably used. However, there is a general corre-lation between the amount of binder used and the amount of fines which can be bound by the structure, 20 i.e., reducing the amount of binder may reduce the quantity of fines which may be immobilized.
The specific surface area of the sorbent will generally be in the range of from about 200 to about 1,000 m2/gram, more preferably from about 200 to 25 about 500 m2/gram. The bulk density of the sorbent is generally in the range of from about 0.5 to about 1.3 g/cc. When pressure is applied in the compres-sive step, an increase in the bulk density, commonly about 10%, will typically occur.
A preferred form of alumina for use in prepar-ing structures in accordance with the present in-vention is an activated alumina available from Rhone-Poulenc Corporation, under the designation DE-4.
This product is spherical in shape and a major por-35 tion of the particles have diameters in the range of ~ 78S9 g from 2 to 5 millimeters. It has a surface area of about 317 m2/gm. For the preferred activated alumina sorbents, ~he surface areas will generally lie in the range of from about 200 to about 500 m2/gm.
S Preferably, the sorbent particles are sub-stantially spherical in shape to maximize the surface area of the sorbent and so that the resulting immo-bilized sorbent will combine a relatively small pres-sure drop associated with a high adsorptive ability.
10 However, because of their spherical shape, the sor-bent particles will not readily adhere to the poly-meric binding material. Accordingly, by heating the sorbent particles prior to mixing with the binding material, the binding material particles become tacky 15 upon mixing and adhere to the sorbent particles.
Polymeric Binding Material:
As used herein, "polymerlc binding material" or 20 "binder" refers to either a thermoplastic or thermo-setting polymeric material, preferably synthetic, which is capable of being shaped under the process conditions of the present invention.
The term "thermoplastic material" describes the 25 preferred polymeric binding material of the present invention and generally refers to any polymeric mat-erial having thermoplastic properties and may include any synthetic or semi-synthetic condensation or poly-merization product. Preferably, the thermoplastic 30 material is a homopolymer or copolymer of a polyole-fin. Most preferable are polyethylene and polypro-pylene, the former being particularly preferred.
Other thermoplastic materials include poly-styrene, polycarbonates, polyurethanes, phenoxy 35 resins, vinyl resins derived from monomers such as ~257~59 -].o-vinyl chloride, vinyl acetate, vinylidine chloride, etcetera, including polyvinyl chloride, copolymers of vinyl chloride with one or more of acrylonitrile, methacrylonitrile, vinylidine chloride, alkyl acryl~
5 ate, alkyl methacrylate, alkyl maleate, alkyl fumar-ate, etcetera.
In some instances, to provide creep resistance, a thermosetting material may be preferred as the polymeric binding material. Suitable for this use 10 are the type of cross-linked polyethylenes used as cable coatings, such as materials formed from blends of polyethylene with peroxide cross-linking agents, such as, for example, benzoyl or dicumyl peroxide present in catalytic amounts. Other examples include 15 those materials in ~hich a prepolymer is reacted with a cross-linking agent to form the product and in-cludes polyurethanes of the type in which a "blocked"
diisocyanate is reacted initially with a difunctional compound, such as a diol, to ~orm the prepolymer 20 which in turn is reacted with a trifunctional com-pound, such as a triol, to form, at the appropriate temperature, the cross-linked polymer. These ther-mosetting mate~ials, which generally cross-link at temperatures between 100-200 degrees C, exhibit pro-25 perties similar to the preferred crystalline thermo-plastic materials discussed below.
The selection of polymeric binding material depends to some extent on the properties sought in the self supporting structure which is formed in part 30 from the binding material. That is, some of the mechanical properties of the immobilized sorbent structure are determined by the physical properties of the binding material. If, for instance, a struc-ture which flexes or which resists fracturing is 35 desired, a thermoplastic powder should be used which ~L2578S9 is not fully crystalline or below its glass trans-ition temperature at the temperature at which the article i5 used. Conversely, a rigid structure re-quires a more crystalline thermoplastic or thermo-setting material.
A requirement of the material selected as the polymeric binding material for use in the present invention is that it have a sufficiently high vis-cosity at the processing temperature so as not to flow and reduce the porosity of the sorbent by "blinding", as discussed below. As also described below, the heating step is conducted in such a manner as to cause the polymeric binding material to begin to soften so that the binder particles lose their original shape and become slightly tacky. The mater-ial should not, however, have a viscosity at the processing temperature such that it flows or blinding may result.
A major portion of the particles of the poly-meric bindiny material should have average particlesizes in the range of about 8 to about 100 micro-meters. When the particle sizes are significantly larger than the upper limit of this range, the powder demonstrates a tendency to settle and a higher weight percentage is required. This may also result, in some instances, in blinding, blinding referring to the tendency for the macropores of the sorbent par-ticle to be covered over with the binding material thereby blocking them and preventing access to the internal micropores of the particle. If binder par-ticle sizes significantly smaller are used, there is also some tendency for blinding to occur.
When thermoplastic materials are used in the present invention, particularly preferred are low density polyethylene powders such as those available ~:2578~9 commercially frolTl USI Cnelllica1s under the trademarks Microthene FN500, FN510 and F~524. These powdered polyethylene powders differ somewl-lat from one another in density and Vicat softening point. Microthene FN500 is somewhat crystalline and has a Vicat softening point of about 195 degrees Fahrerlheit. This material provides the finished structure with substan-tial rigidity.
In addition, wherl a somewhat more flexib]e structure is desired, up to 10 percent of a second ethylenically unsaturated 0 Illaterial, such as vinyl acetate, may be copolymerized with the ethylene -to provide an amorphous thermoplastic binding material.
copolymer oE -this type exhibits less of a tendency to b]ind and also imparts some energy or shock absorbency properties to the immobilized sorbent s-tructure, thereby reducirlg the tendency of the structure to fracture when handled with less caution than -that required by some of the struc-ture using more crystalline homopolymers. A suitable rnaterial of this type comprising 9 percent vinyl acetate copolymerized with polyethylene is avail-able from USI Chemicals under the trademark Microthene FN532.
The binder is present suitably in an amount of about 1 to about 7, preferably about 2 -to about 5, percent by weight, all percen-tages based on the weight of the to-tal mixture comprising binder, sorbent particles and, preferably, a mixiny aid.
~ n anti-agglorneratirlg agen-t or mixing aid, such as fumed silica, is preferably added to the binder in order to inhibit adhesion between particles of the polymeric binding material. Usually, not more than 0.5% by weight of the mixing aid should be used (based on the total weight of the binder and the mixing aid).
~ 57~3S~
Self-Supporting Immobilized Sorbent Structure:
.
~ o form the self-supporting immobilized sorbent structure of the present invention, sorbent particles 5 are preheated and then mixed wi~h an appropriate amount, as indicated above, of polymeric binding material in any suitable manner. When contact is made between a binding material particle and a sor-bent particle, some heat will he transferred from the 10 preheated sorbent particle to the polymeric binder material particle, rendering the polymeric binder material particle tacky, so that the binder material particle will adhere to the sorbent particle. It is important that the temperature to which the sorbent 15 particles are preheated does not greatly exceed the temperature at which the binding material part-cles become softened and take on a semi-liquid consis-tency, i.e., the solid-liquid transition temperature.
The mixture is then allowed to cool while it is 20 mixed so that the binding material particles will become less tacky and will not adhere to one another (will be free flowing). However, the adhesion be-tween particles of polymeric binding material and sorbent material will remain substantially unaffected 25 by the decrease in temperature. An anti-agglomer-ating agent or mixing aid, such as fumed silica, may be combined with the binder prior to combining the binder with the sorbent to further inhibit adhesion between binding material particles.
The resulting dispersion will remain substan-tially uniform, since substantially all of the bind-ing material particles will be adhered to a sorbent particle, and therefore, even though the binding material particles are generally smaller than the 35 sorbent particles, dlJe to their adhesion to the sor--~ ~257~5~3 bent particles, they will not fall to the bottom of the mixing vessel.
It is usually unnecessary to use any particular precautions or undue care to avoid crushing the sor-S bent which would increase the fines content, duringblending, since the polymeric binding agent is cap-able of retaininq the fines. Care should be em-ployed, however, when the sorbent particles already contain a signi~icant amount of fines.
Once mixing has been completed and a substan-tially uniform mixture has been obtained, the mixture is preferably transferred to a mold having the par-ticular volume and shape desired. Alternatively, the vessel in which the components are mixed can also 15 serve as the mold.
Heat is then applied to the contents of the mold to provide an immobilized sorbent structure.
Pressure may be applied while the mixture is at an elevated tempecature to impart greater compressive 20 strength to the structure. To immobilize the sorbent particles, particularly the fines, the particles should be effectively secured or trapped by the bind-er. Effective trapping of fines occurs (with the consequent increase in strength of the structure with 25 the minimal reduction of sorptive properties) and the minimal increase in pressure drop results when the sorbent particles and fines are uniformly distributed in the self-supporting structure. This does not mean that each sorbent particle is completely enveloped in 30 the polymeric binding material. On the contrary, it is preferred that each particle merely be held in place by the polymeric binding material. This may be accomplished by raising the temperature of the mix-ture to about the solid-liquid transition temperature 35 of the binder to produce a suitable consistency in the polymeric binding material. Use of the proper temperature for a particular polymeric binding mater-ial causes that material to be softened and form a semi-solid o{ semi-liquid consistency. That is, the 5 material is softened to the extent that no well de-fined binder particles exist which have the physical attributes of a solid yet the material does not flow as does a liquid. At this temperature or stage, termed herein as the "solid-liquid transition stage", ~10 which is about 50 to about 90 degrees Fahrenheit above the Vicat softening point, the polymeric bind-ing material exhibits an increased tackiness. This tackiness, probably resulting from increased mobility of the molecular chains of the molecules, provides improved interparticle adhesion. The solid-liquid transition stage i5 not to be confused with a melting point in which solid and liquid phases exist in dy-namic equilibrium with one another. At the solid-liquid transition stage, the polymeric binding mat-20 erial may be thought to be in a hybrid state betweensolid and liquid states. When at this stage, the mixture of polymeric binding material and sorbent - particles may be compressed sufficiently by appli-cation of pressure to increase the number of contact 25 points between adjacent particles and increase inter-particle bonding, providing thereby increased com-pressive strength with retention of sorptive prop-erties. The solid-liquid transition stage for a polymeric binding material is not as sharply defined 30 as is the melting point of a pure crystalline mater-ial, and, in some instances, the temperature range of this stage is somewhat broad~ However, it is still undesirable to use temperatures in the present proc-ess which are much above the temperature range of the 35 solid-liquid transition stage since the polymeric ~ ~2S7859 -16~
binding material then exhibits the characteristics of a liquid in that it tends to readily flow. This is to be avoided since blinding of the pores of the sorbent may occur and formation of a mass or block of 5 coated sorbent particles in which the sorption and gas permeability characteristics have been reduced or lost may also result.
The heat required to raise the temperature of the mixture of polymeric binding material and sorbent 10 to the temperature at which the polymeric binding material is at its solid-liquid transition stage may ¦ be supplied by any conventional equipment, such as, for example, a forced hot air or convection oven, a heat jacketed mold, an infrared heater, or a heated 15 roller or rollers. Depending on the apparatus used for heating the sample and the volume of the mold, heating to the solid-liquid transition stage may take from about 10 minutes to an hour or more.
The compressive or crush strength of the self-20 supporting structures increases as the magnitude ofthe pressure applied during the forming step at the solid-liquid transition stage is increased. Like-wise, the pressure drop across the self-supporting structure increases as the magrlitude of pressure 25 applied to the sorbent/polymeric binding material mixture during formation of the structure is in-creased.
Pressure may be supplied to the mold by place-ment between two pressure rollers (calendering), by 30 appropriate placement of a weight, by hydraulic means, such as by use of a piston~ or by any other device and method known for application of pressure to a mold.
While the compressive pressure may be applied 35 during or after elevation of the temperature to the ~ ~ ~,5785~ 7 solid-liquid transition stage, it is preferred to raise the temperature to, or very close to, the sol-id-liquid transition stage where the polymeric bind-ing material is soft and about to flow prior to ap-5 plication of pressure. Once the mixture is raised tothe temperature of the solid-liquid transition stage and thermal equilibrium is established, pressure is typically applied for from about 1 to about 10 min-utes. The temperature of the mixture must be held 10 within the range of the solid-liquid transition stage of the polymeric binding material for about the first minute during which the pressure is applied.
Pressures in the range of up to the crush strength of the sorbent, which is generally from 15 about 100 to about 200 psi, may be used, albeit, from a practical perspective, from about 0.3 to about 50 psi are preferred, more preferably from about 0.3 to about 20. That is, generally the compressive strength of the self-supporting immobilized structure is di-20 rectly related to the pressure applied at the solid-liquid transition stage. For most purposes, very high compressive strengths are not required. Thus, by using lower pressures during the process, simpler equipment may be employed and a self-supporting struc-25 ture having adequate strength, particularly compres-sive or crush strength, to permit ease of handling and transport, as well as minimum pressure drop across the structure and maximum sorption character-istics, is achieved while substantially eliminating 30 the formation of fines and retaining or immobilizing previously existing fines.
The resulting structure is capable of being desorbed or regenerated and therefore the sorptive capability of the sorbent can be reused, with the 35 chance of the sorbent escaping being greatly reduced.
~ ~257~5~ ~
While the invention is susceptible to various modifications and alternative forms, certain specific embodiments thereof are described in the examples set forth below. It should be understood, however, that 5 these examples are not intended to limit the inven~
tion to the particular forms disclosed but, on the contrary, the intention is to cover all modifica-tions, equivalents and alternatives falling within the spirit and scope of the invention.
~ 1 0 Examp_es:
General Method For Preparation Of Examples 1 To 6:
.
Examples 1 to 6 were prepared by essentially the same procedure as set out below. Specific di~-ferences in conditions or materials are noted below.
1000 gram portions of Rhone-Poulenc DE-4 ac- `
20 tivated alumina beads were weighed and placed in 2 liter glass jars. The activated alumina was gener-ally of diameter from about 2 to about 5 millimeters.
Each open glass jar was then placed in an oven, for about one hour, preheated to about 270 degrees Fahr-25 enheit which temperature is approximately equal tothe solid-liquid transition temperature of polyethyl-ene, the polymeric binder powder being used.
Separate portions of Microthene FN500 and FN510 polyethylene powder from U. S. I Chemicals (Micro-30 thene FN500 and FN510 are both low density polyethyl-ene; FN510 has a slightly higher Vicat softening point than FN500), were then mixed with fumed silica ~ 4~ k- ~f (Sipernat 17-fr~m Degussa Corporation), which acts as an anti-agglomeration agent for the polyethylene so 35 that the resulting mixture was 0.5 percent by total 7 ~9 weight fumed silica. The homogenously blended mix-ture was then weighed into appropriate pcrtions to be added to the pre-heated activated alumina.
The glass jars were then removed from the oven 5 and the contents of each jar of hot alumina were transferred to separate 4 liter mixing vessels. Ap-propriate pre-weighed portions of Microthene/fumed silica were immediately blended into each vessel containing the hot alumina particles. Stirring was 1~ continued until the mix cooled to about 70 degrees Centigrade to ensure that the polyethylene powder had adhered to the alumina.
In order to mold the above material, a cylin-drical mold of the desired dimensions was filled with 15 the alumina/polyethylene/silica mixture. The mold was restrained on the top and bottom by perforated metal plates that were placed within the cylinder.
The assembly was then placed in an oven pre-heated to a molding temperature at about the solid-liquid tran-~0 sition temperature of the polyethylene. After re-maining at this temperature for about one hour, or until a uniform temperature was attained, the mold was removed from the oven and placed on a hydraulic press. Pressure was then applied for about one min-25 ute. The composition, molding temperature and pres-sure applied in each of the examples are shown in Table 1. The cooled immobilized activated alumina structures produced by the examples were found to be self supporting.
~257~5~3 ~
--,.o--Example Percentage of Molding Compressive Polyethylene Temperature Pressure based on weight (Degrees of Polyethylene/ Fahrenheit) ~lumina/Fumed Silica Mixture (FN #) 1 ~.0 (500) 260 10 psi
2 5.0 (500) 260 10 psi
3 3.0 (510) 275 ]0 psi
4 5.0 (500) 260 10 psi 15 5 5.0 (500) ~`60 0.3 psi 6 3.5 (500) 260 1~ psi The following tests were performed on the im-20 mobilized activated alumina structures formed in the above examples:
I. Dynamic Water Sorption Test - Examples 1-3 This test measured the ability of a sorbent bed~
to remove water vapor from an airstream that was passed through the bed. In all instances, the air-stream was provided at the same constant flow rate from a compressed air supply that had been filtered 30 for both particulate and hydrocarbon gases.
Water vapor was supplied to this stream at the desired concentration by means of a medical type humidifier (available from Bennett Corporation).
The airstream flow rate through the bed was 35 measured with a Model 1/2-21-G-10/80 flow meter (from ~ ~57~3~
Fischer and Porter Company)~ The flow rate through the sorbent bed test fixture determined the linear velocity and average gas residence time or a test.
The concentration of water vapor enter:ing the
I. Dynamic Water Sorption Test - Examples 1-3 This test measured the ability of a sorbent bed~
to remove water vapor from an airstream that was passed through the bed. In all instances, the air-stream was provided at the same constant flow rate from a compressed air supply that had been filtered 30 for both particulate and hydrocarbon gases.
Water vapor was supplied to this stream at the desired concentration by means of a medical type humidifier (available from Bennett Corporation).
The airstream flow rate through the bed was 35 measured with a Model 1/2-21-G-10/80 flow meter (from ~ ~57~3~
Fischer and Porter Company)~ The flow rate through the sorbent bed test fixture determined the linear velocity and average gas residence time or a test.
The concentration of water vapor enter:ing the
5 sorbent bed was measured ~sing a Hygrocon Model B
(from Phys-Chemical Research Corporation) relative humidity meter. The temperature of the airstream remained constant at 24 degrees C.
The concentration of water vapor exiting the 10 sorbent bed was measured using an Alnor Model 70004 dew point meter (from Alnor Instrument Company).
The sorbent bed to be tested was sealed in a test fixture having a cross sectional area of 9 square inches and a depth of 4.0 inches.
Tests were commenced by adjusting the airstream flow rate to the desired value, (as reported in the test results), and setting the relative humidity to 40~ + 3~. The test sample bed was then connected to the airstream at the inlet and to the dew point meter 20 at the outlet. The dew point of the effluent from the test bed was then recorded at specific time in-tervals.
The results for the dynamic water sorption test are shown in Table 2.
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The control structure constituted a granular bed of the same dimensions (3.4 inch O.D. X 4.0 inches deep), as the immobilized sorbent structures, however the control contained no Microthene binding material.
Following the control test, the activated alu~ina was removed from the control bed, dried, and used to pre-pare the immobilized structure of Example #1.
The results show that the efficiency of removal of water vapor was nearly identical for the control and for the immobilized examples.
II. Compressive Strength Test The compressive strength test measured the abil-ity of the immobilized sorbent beds to resist failurewhen subjected to compressive force.
The force applied to the samples during the test was measured by a digital force gauge. In these exam-ples, a Chatillion Model EFG 100, whose readout is 20 designed to directly read the pressure per square inch in pounds, was used to measure the compressive force.
Samples in the form of cylinders about 1 inch in diameter and 1.5 inches in length were restrained on each end by 1 inch diameter circular plates, one mov-25 able, the other fixed, attached to the force gauge.The movable plate was gradually moved toward the sta-tionary plate, thereby increasing the force applied to the test sample. The value reported in Table 3 under the heading 1'Compressive Strength" is the value of the 30 applied compressive force (in psi) at which deforma-tion of the test sample was first observed.
Test samples for Examples 4 and 5 (two of each) were prepa{ed following the General Method, as de-scribed above and tested.
~257~359 ~9 __ Example Compressive Compressive Pressure Strength (During Molding) (psi) (psi) _ 0 3 ~a 0.3 26 The results indicate that higher compressive strengths for immobilized sorbent beds can be achieved 15 by applying higher pressures during molding. The compressive strength of the non-immobilized sorbent is not measurable because the material is mobile and not self supporting.
20 III. Dust Release Test - The Dust Release Test was designed to measure the amount of sorbent particles lost from a sample when subjected to a constant vibration.
The apparatus used to perform the test consisted of three cylinders placed with their openings in ser-ies and secured to one another by a clamp. Rubber gaskets were used to separate each of the cylinders.
In the ~first cylinder, a high efficiency Emflon~ air 30 filter manufactured by Pall Corporation was included and in the third or last cylinder a nylon 66 collec-tion membrane having a 0.8 ~m absolute pore rating was located. The sample being tested, having been formed according to the General Method and having an outer 35 diameter of 3.4 inches and a length of 1.3 inches, was ~2~7~59 placed in the intermediate or second cylinder. The cylinders were secured to a vibrating dental table ~hich was adjusted to provide a vibrating force of 4 G. Additionally, a vacuum for drawing air through the 5 cylinders at a specified flow rate from the high e~-ficiency air filter cylinder in the direction of col-lection was provided.
The nylon 66 membrane was weighed and mounted in the collection cylinder. The cylinders were then 10 clamped together and secured to the table. ~ibration and air flow through the apparatus were initiated simultaneously, the air flow eate having been adjusted to 8 liters per minute.
The test was conducted for 60 minutes, after 15 which the collection membrane was removed and re-weighed, the difference in weight being the amount of sorbent lost by the sample.
Sample Prepared Sorbent By Example Loss (mg)
(from Phys-Chemical Research Corporation) relative humidity meter. The temperature of the airstream remained constant at 24 degrees C.
The concentration of water vapor exiting the 10 sorbent bed was measured using an Alnor Model 70004 dew point meter (from Alnor Instrument Company).
The sorbent bed to be tested was sealed in a test fixture having a cross sectional area of 9 square inches and a depth of 4.0 inches.
Tests were commenced by adjusting the airstream flow rate to the desired value, (as reported in the test results), and setting the relative humidity to 40~ + 3~. The test sample bed was then connected to the airstream at the inlet and to the dew point meter 20 at the outlet. The dew point of the effluent from the test bed was then recorded at specific time in-tervals.
The results for the dynamic water sorption test are shown in Table 2.
~ ~ZS78S~ ~
~0 U ~ d~
~: o Ln o u~
~ ~ ~ oo ~ o~ oo ~1 ~ ~
r~ ~ :>
-~ o ~ a~
~0 ~, 1 0 Q, r~
~ c~ ~
:> o^ o ~1~ ~ o o v v _~ ~ o o o ~ 4~ ~ o :~ ~, o o o o o ~O ~, o o o n v c o a) a) ~
~ r~
1 5 ~ O ~ o ~ o r~--m ~:
c a J -_l ~ ~ E4 Q~ O O o o o Ul :~ 0 0 0 c ~ 3 ~ ~ r o o a .
C O
.
.
E~ Q. a~
a) ~ v u~ ,a ~ V
O
L~ C ~ c aJ
u~
~: ~ ~ . ~ e c L~l O ~ ~
,~ 4~ 0 v ~ ~ ~) ~ z c x O
~1 r~ ~
7~35~ 1~
The control structure constituted a granular bed of the same dimensions (3.4 inch O.D. X 4.0 inches deep), as the immobilized sorbent structures, however the control contained no Microthene binding material.
Following the control test, the activated alu~ina was removed from the control bed, dried, and used to pre-pare the immobilized structure of Example #1.
The results show that the efficiency of removal of water vapor was nearly identical for the control and for the immobilized examples.
II. Compressive Strength Test The compressive strength test measured the abil-ity of the immobilized sorbent beds to resist failurewhen subjected to compressive force.
The force applied to the samples during the test was measured by a digital force gauge. In these exam-ples, a Chatillion Model EFG 100, whose readout is 20 designed to directly read the pressure per square inch in pounds, was used to measure the compressive force.
Samples in the form of cylinders about 1 inch in diameter and 1.5 inches in length were restrained on each end by 1 inch diameter circular plates, one mov-25 able, the other fixed, attached to the force gauge.The movable plate was gradually moved toward the sta-tionary plate, thereby increasing the force applied to the test sample. The value reported in Table 3 under the heading 1'Compressive Strength" is the value of the 30 applied compressive force (in psi) at which deforma-tion of the test sample was first observed.
Test samples for Examples 4 and 5 (two of each) were prepa{ed following the General Method, as de-scribed above and tested.
~257~359 ~9 __ Example Compressive Compressive Pressure Strength (During Molding) (psi) (psi) _ 0 3 ~a 0.3 26 The results indicate that higher compressive strengths for immobilized sorbent beds can be achieved 15 by applying higher pressures during molding. The compressive strength of the non-immobilized sorbent is not measurable because the material is mobile and not self supporting.
20 III. Dust Release Test - The Dust Release Test was designed to measure the amount of sorbent particles lost from a sample when subjected to a constant vibration.
The apparatus used to perform the test consisted of three cylinders placed with their openings in ser-ies and secured to one another by a clamp. Rubber gaskets were used to separate each of the cylinders.
In the ~first cylinder, a high efficiency Emflon~ air 30 filter manufactured by Pall Corporation was included and in the third or last cylinder a nylon 66 collec-tion membrane having a 0.8 ~m absolute pore rating was located. The sample being tested, having been formed according to the General Method and having an outer 35 diameter of 3.4 inches and a length of 1.3 inches, was ~2~7~59 placed in the intermediate or second cylinder. The cylinders were secured to a vibrating dental table ~hich was adjusted to provide a vibrating force of 4 G. Additionally, a vacuum for drawing air through the 5 cylinders at a specified flow rate from the high e~-ficiency air filter cylinder in the direction of col-lection was provided.
The nylon 66 membrane was weighed and mounted in the collection cylinder. The cylinders were then 10 clamped together and secured to the table. ~ibration and air flow through the apparatus were initiated simultaneously, the air flow eate having been adjusted to 8 liters per minute.
The test was conducted for 60 minutes, after 15 which the collection membrane was removed and re-weighed, the difference in weight being the amount of sorbent lost by the sample.
Sample Prepared Sorbent By Example Loss (mg)
6 <0.1 Control 33.2 (non-immobilized activated alumina) As the above results indicate, loose activated alumina particles (as in the control test) contain or 30 release large amounts of dust or fines. However, the immobilized sorbent beds prepared in accordance with the present invention resulted in a substantially reduced amount of fines.
~257~59 The temperature to which the sorbent particles are preheated is determined by consideration of a number of factors. The primary criterion is that the binder particles ~hen added to the preheated sorbent 5 particles should be heated (by heat transfer) to a temperature sufficiently high that they become suffic-iently tacky to adhere to the sorbent particles while not becoming so tacky that they bind tlle sorbent particles together and preclude free flow of the 10 sorbent particles upon cooling. That is, the tem-perature to which the sorbent particles are heated should not be so high as to result in the binder material particles adhering to each other to such an extent that ~he sorbent particies are not free flow-1~ ing upon cooling. The temperature to which the sor-bent particles are heated should take into account any heat loss from the particles prior to mixing with the sorbent. For example, if mixing is initiated immediately, then the heat loss will be minimal and a 20 lower temperature will be required. Also, the rela-tive heat capacities of the sorbent and the binder material as well as the relative amounts of the sor-bent and the binder material are factors to be con-sidered. That is, the more binder that is used, the 25 more will be the amount of the heat required to ob-tain the requisite level of tackiness to ensure ad-hesion of the binder particles to the sorbent par-ticles. Similarly, as the heat capacity of the binder increases and/or the heat capacity of the 30 sorbent decreases, the temperature to which the sor-bent is heated should be increased. Conversely, as the heat capacity of the binder decreases and/or the heat capacity of the sorbent increases, the temper-ature to which the sorbent is heated should be de-35 creased.
~ 7~
Typically for the preferred low density, poly-ethylene binder, the sorbent is heated to a tempera~
ture of from about 250 to about 280 degrees Fahren-heit.
1 o
~257~59 The temperature to which the sorbent particles are preheated is determined by consideration of a number of factors. The primary criterion is that the binder particles ~hen added to the preheated sorbent 5 particles should be heated (by heat transfer) to a temperature sufficiently high that they become suffic-iently tacky to adhere to the sorbent particles while not becoming so tacky that they bind tlle sorbent particles together and preclude free flow of the 10 sorbent particles upon cooling. That is, the tem-perature to which the sorbent particles are heated should not be so high as to result in the binder material particles adhering to each other to such an extent that ~he sorbent particies are not free flow-1~ ing upon cooling. The temperature to which the sor-bent particles are heated should take into account any heat loss from the particles prior to mixing with the sorbent. For example, if mixing is initiated immediately, then the heat loss will be minimal and a 20 lower temperature will be required. Also, the rela-tive heat capacities of the sorbent and the binder material as well as the relative amounts of the sor-bent and the binder material are factors to be con-sidered. That is, the more binder that is used, the 25 more will be the amount of the heat required to ob-tain the requisite level of tackiness to ensure ad-hesion of the binder particles to the sorbent par-ticles. Similarly, as the heat capacity of the binder increases and/or the heat capacity of the 30 sorbent decreases, the temperature to which the sor-bent is heated should be increased. Conversely, as the heat capacity of the binder decreases and/or the heat capacity of the sorbent increases, the temper-ature to which the sorbent is heated should be de-35 creased.
~ 7~
Typically for the preferred low density, poly-ethylene binder, the sorbent is heated to a tempera~
ture of from about 250 to about 280 degrees Fahren-heit.
1 o
Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for immobilizing inorganic sorbent part-icles with a polymeric, thermoplastic binding material, the pro-cess comprising (a) preheating the inorganic sorbent particles, the major portion of which have particle sizes in the range of from 1 to 10 millimeters, to an elevated temperature; (b) mixing the heated sorbent particles with particles of the polymeric, thermoplastic binding material to form a mixture comprising from one to seven percent polymeric, thermoplastic binding material based on the weight of the mixture, the particles of polymeric, thermoplastic binding material being adhered to the sorbent par-ticles; and (c) heating the mixture to about the solid-liquid transition temperature of said polymeric, thermoplastic binding material with or without pressure, thereby forming a structure which, upon cooling, is self-supporting, in which the formation of sorbent fines is substantially eliminated and in which the sorption characteristics of the inorganic sorbent particles are substantially retained.
2. The process of claim 1, wherein the solid-liquid transition temperature is 10 to 32.2°C (50 to 90°F) above the Vicat softening point of the polymeric, thermoplastic binding material.
3. The process of claim 1, wherein a major portion of the particles of said polymeric, thermoplastic binding material has particle sizes in the range of 8 to 100 micrometers.
4. The process of claim 1, wherein pressure from 0.02 to 3.45 bars (0.3 to 50 psi) is applied in step (c).
5. The process of claim 1, wherein said polymeric, thermoplastic binding material comprises a polyolefin.
6. The process of claim 5, wherein said polyolefin comprises polyethylene.
7. The process of claim 1, wherein said inorganic sor-bent particles comprise alumina.
8. The process of claim 1, wherein said polymeric, thermoplastic binding material is low density polyethylene, a major portion of which has particle sizes in the range of 8 to 100 micrometers and is present in an amount of from 2 to 5% by weight, based on the weight of said mixture, said sorbent is heated to a temperature of from 121.1 to 137.8°C (250 to 280°F) prior to mixing with said polymeric, thermoplastic binding mate-rial and a pressure of from 0.02 to 1.3% bars (0.3 to 20 psi) is applied to said mixture while said mixture is at a temperature of 20 to 32.2°C (50 to 90°F) above the Vicat softening point of said polymeric, thermoplastic binding material.
9. A self-supporting, immobilized inorganic sorbent structure substantially free of mobile sorbent fines, having a low pressure drop and high sorptive capacity comprising inorganic sorbent particles, a major portion of which has particle sizes in the range of from 1 to 10 millimeters, one to seven percent by weight of a polymeric binding material, the percentage of said polymeric binding material based on the weight of said structure, said structure having a sorptive capacity substantially as high as the inorganic sorbent particles prior to immobilization and the ability to withstand compressive forces of at least about 1.38 bars (20 psi).
10. The self-supporting structure according to claim 9, wherein a major portion of said particles of said polymeric bind-ing material has particle sizes in the range of from 8 to 100 micrometers.
11. The self-supporting structure according to claim 9, wherein the percentage by weight of said polymeric binding mate-rial is from 2 to 5 weight percent.
12. The self-supporting structure according to claim 9, wherein the polymeric binding material comprises a polyolefin.,
13. The self-supporting structure according to claim 12, wherein the polyolefin comprises low density polyethylene.
14. The self-supporting structure according to claim 9, wherein said inorganic sorbent is an inorganic oxide.
15. The self-supporting structure according to claim 14, wherein said inorganic oxide is selected from the group con-sisting of alumina, magnesia, silica, or mixtures thereof.
16. A self-supporting, immobilized inorganic sorbent structure substantially free of mobile inorganic sorbent fines having a low pressure drop and high sorptive capacity comprising inorganic sorbent particles; one to seven percent by weight of a polymeric binding material, the percentage of said polymeric binding material based on the weight of said structure and the major portion of the particles thereof having particle sizes in the range of from 8 to 100 micrometers, said structure having a sorptive capacity substantially as high as the inorganic sorbent particles prior to immobilization and the ability to withstand compressive forces of at least 1.38 bars (20 psi).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/640,447 US4665050A (en) | 1984-08-13 | 1984-08-13 | Self-supporting structures containing immobilized inorganic sorbent particles and method for forming same |
| US640,447 | 1984-08-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1257859A true CA1257859A (en) | 1989-07-25 |
Family
ID=24568277
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488218A Expired CA1257859A (en) | 1984-08-13 | 1985-08-07 | Self-supporting structures containing immobilized inorganic sorbent particles and method for forming same |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4665050A (en) |
| EP (1) | EP0172714A1 (en) |
| JP (1) | JPS6157240A (en) |
| CA (1) | CA1257859A (en) |
| GB (1) | GB2163064B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006092043A1 (en) * | 2005-03-03 | 2006-09-08 | Queen's University At Kingston | Polymer entrapped particles |
Families Citing this family (108)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5127925A (en) * | 1982-12-13 | 1992-07-07 | Allied-Signal Inc. | Separation of gases by means of mixed matrix membranes |
| US5078132A (en) * | 1985-08-28 | 1992-01-07 | Minnesota Mining And Manufacturing Company | Bonded adsorbent structures and respirators incorporating same |
| CA1266854A (en) * | 1985-08-28 | 1990-03-20 | David L. Braun | Bonded adsorbent structures and respirators incorporating same |
| US5017318A (en) * | 1986-04-07 | 1991-05-21 | Amway Corporation | Method of making a water filter |
| US5135904A (en) * | 1988-02-05 | 1992-08-04 | Tayca Corporation | Adsorbent composition for malodorous gases |
| US4999330A (en) * | 1988-03-22 | 1991-03-12 | Universite Du Quebec A Trois-Rivieres | High-density adsorbent and method of producing same |
| US5552048A (en) * | 1988-06-15 | 1996-09-03 | Pall Corporation | Two pleated filter composite having cushioning layers |
| US5084178A (en) * | 1988-06-15 | 1992-01-28 | Pall Corporation | Corrugated filter arrangement with support layer and flow channels |
| US5252207A (en) * | 1988-06-15 | 1993-10-12 | Pall Corporation | Wrap member having openings |
| US4925631A (en) * | 1988-09-26 | 1990-05-15 | Figgie International, Inc. | Method of casting a hopcalite filter and cast ceramic fiber-hopcalite |
| JPH02139086A (en) * | 1988-11-21 | 1990-05-29 | Tokuyama Soda Co Ltd | Water purification agent composition |
| FR2641199B1 (en) * | 1988-12-30 | 1992-01-10 | Inst Francais Du Petrole | METHOD AND DEVICE FOR MANUFACTURING A FILTER CARTRIDGE |
| US5019311A (en) * | 1989-02-23 | 1991-05-28 | Koslow Technologies Corporation | Process for the production of materials characterized by a continuous web matrix or force point bonding |
| DE69018312T2 (en) * | 1989-05-23 | 1995-12-14 | Sasaki Chemicals Co Ltd | Moisture absorbent compositions. |
| EP0450047A4 (en) * | 1989-10-18 | 1992-06-24 | Us Commerce | Polymer bead containing immobilized metal extractant |
| AT392954B (en) * | 1989-11-29 | 1991-07-25 | Zwittnig Leopold | Oil binder |
| US5354474A (en) * | 1989-12-22 | 1994-10-11 | The Dow Chemical Company | Dynamic membrane separation process for improved selectivity |
| US5114584A (en) * | 1990-12-13 | 1992-05-19 | Refractron Technologies Corporation | Filter dryer body |
| US5249948A (en) * | 1991-04-08 | 1993-10-05 | Koslow Technologies Corporation | Apparatus for the continuous extrusion of solid articles |
| US5332426A (en) * | 1992-07-29 | 1994-07-26 | Minnesota Mining And Manufacturing Company | Agglomerated activated carbon air filter |
| CA2139502C (en) * | 1992-07-29 | 2004-11-30 | Yuan-Ming Tang | Agglomerated activated carbon air filter |
| US5384047A (en) * | 1993-01-22 | 1995-01-24 | Refractron Technologies Corporation | Filter dryer body |
| GB9412856D0 (en) | 1994-06-27 | 1994-08-17 | Normalair Garrett Ltd | Canister for inorganic sorbent particles |
| IT1275365B (en) * | 1994-07-22 | 1997-08-05 | P I L S R L | ABSORBENT PRODUCT IN SHEET USED IN THE PACKAGING OF FOODS THAT RELEASE LIQUIDS AND GASES |
| DE4442713C2 (en) * | 1994-12-01 | 1999-12-23 | Freudenberg Carl Fa | Adsorption air filter and process for its manufacture |
| US6216693B1 (en) | 1995-01-20 | 2001-04-17 | 3M Innovative Properties Company | Respirator having a compressible press fir filter element |
| US6214255B1 (en) | 1995-04-19 | 2001-04-10 | Capitol Specialty Plastics, Inc. | Desiccant entrained polymer |
| US6486231B1 (en) | 1995-04-19 | 2002-11-26 | Csp Technologies, Inc. | Co-continuous interconnecting channel morphology composition |
| US6194079B1 (en) | 1995-04-19 | 2001-02-27 | Capitol Specialty Plastics, Inc. | Monolithic polymer composition having an absorbing material |
| USRE40941E1 (en) * | 1995-04-19 | 2009-10-20 | Csp Technologies, Inc. | Monolithic polymer composition having a releasing material |
| US6316520B1 (en) | 1995-04-19 | 2001-11-13 | Capitol Specialty Plastics, Inc. | Monolithic polymer composition having a releasing material |
| US6221446B1 (en) | 1995-04-19 | 2001-04-24 | Capitol Specialty Plastics, Inc | Modified polymers having controlled transmission rates |
| US6177183B1 (en) | 1995-04-19 | 2001-01-23 | Capitol Specialty Plastics, Inc. | Monolithic composition having an activation material |
| US6080350A (en) | 1995-04-19 | 2000-06-27 | Capitol Specialty Plastics, Inc. | Dessicant entrained polymer |
| US6174952B1 (en) | 1995-04-19 | 2001-01-16 | Capitol Specialty Plastics, Inc. | Monolithic polymer composition having a water absorption material |
| US6124006A (en) * | 1995-04-19 | 2000-09-26 | Capitol Specialty Plastics, Inc. | Modified polymers having controlled transmission rates |
| US6130263A (en) * | 1995-04-19 | 2000-10-10 | Capitol Specialty Plastics, Inc. | Desiccant entrained polymer |
| US6460271B2 (en) | 1995-04-19 | 2002-10-08 | Csp Technologies, Inc. | Insert having interconnecting channel morphology for aldehyde absorption |
| US5911937A (en) * | 1995-04-19 | 1999-06-15 | Capitol Specialty Plastics, Inc. | Desiccant entrained polymer |
| EP0871533A1 (en) * | 1995-05-12 | 1998-10-21 | Donaldson Company, Inc. | Filter device |
| WO1996037288A1 (en) * | 1995-05-26 | 1996-11-28 | Hitachi Chemical Company, Ltd. | Environment purifying material |
| JPH11508185A (en) * | 1995-06-20 | 1999-07-21 | ドナルドソン カンパニー，インコーポレイティド | Filter and manufacturing method of filter |
| US5639550A (en) * | 1995-06-21 | 1997-06-17 | Specialty Media Corporation | Composite particulate material and process for preparing same |
| US5846696A (en) * | 1995-10-13 | 1998-12-08 | Eastman Kodak Company | Blends of polymer and zeolite molecular sieves for packaging inserts |
| US5696199A (en) * | 1995-12-07 | 1997-12-09 | Minnesota Mining And Manufacturing Company | Pressure-sensitive adhesive polyacrylate polymer and method of making |
| DE19654949C2 (en) * | 1996-03-29 | 2003-02-27 | Sandler Helmut Helsa Werke | Adsorptive filter body |
| US5817263A (en) * | 1996-08-30 | 1998-10-06 | Amway Corporation | End flow filter and method of making same |
| JPH10118488A (en) * | 1996-10-21 | 1998-05-12 | Nagoya Yuka Kk | Adsorbing material |
| US6465532B1 (en) | 1997-03-05 | 2002-10-15 | Csp Tecnologies, Inc. | Co-continuous interconnecting channel morphology polymer having controlled gas transmission rate through the polymer |
| US6485813B1 (en) | 1997-03-07 | 2002-11-26 | Koslow Technologies Corp. | Method of stabilizing composite media and media produced thereby |
| EP0904834A3 (en) * | 1997-09-26 | 1999-04-21 | HELSA-WERKE HELMUT SANDLER GmbH & CO. KG | Adsorptive filter body |
| FR2780052B1 (en) * | 1998-06-23 | 2000-07-21 | Ceca Sa | ACTIVATED CARBON AGGLOMERATES, PROCESS FOR THEIR PREPARATION AND THEIR USE AS ADSORPTION AGENTS |
| AU757555B2 (en) * | 1998-09-22 | 2003-02-27 | Msa Europe Gmbh | Polymer-bonded granular adsorptive, absorptive, chemisorptive, or catalytically active material |
| US6083439A (en) * | 1998-09-25 | 2000-07-04 | Auergesellschaft Gmbh | Polymer-bonded material |
| US6270609B1 (en) | 1999-01-11 | 2001-08-07 | 3M Innovative Properties Company | Hard disk drive filter |
| US6696002B1 (en) | 2000-03-29 | 2004-02-24 | Capitol Security Plastics, Inc. | Co-continuous interconnecting channel morphology polymer having modified surface properties |
| JP4070392B2 (en) * | 2000-08-01 | 2008-04-02 | 富士通株式会社 | Method and apparatus for preparing fluorine-based solvent and purification method |
| US7335422B2 (en) * | 2002-04-25 | 2008-02-26 | Sud-Chemie Inc. | Absorbent polymeric material |
| US7389877B2 (en) * | 2000-08-28 | 2008-06-24 | Sud-Chemie Inc. | Apparatus for packaging electronic components including a reel entrained with desiccating material |
| US7201959B2 (en) * | 2002-04-25 | 2007-04-10 | Sud-Chemie Inc. | Absorbent polymeric composition |
| US6827218B1 (en) | 2000-08-28 | 2004-12-07 | Sud-Chemie Inc. | Packaging container for electronic components |
| US6645271B2 (en) | 2001-06-08 | 2003-11-11 | Donaldson Company, Inc. | Adsorption element and methods |
| US20050092176A1 (en) * | 2001-06-08 | 2005-05-05 | Lefei Ding | Adsorptive filter element and methods |
| US6793866B2 (en) * | 2001-10-23 | 2004-09-21 | Equistar Chemicals, Lp | Process for producing bonded activated carbon structures and articles |
| US7314895B2 (en) * | 2001-12-19 | 2008-01-01 | Csp Technologies, Inc. | Thermoplastic composition comprising a CO2 releasing material |
| US6919029B2 (en) * | 2002-02-14 | 2005-07-19 | Trustees Of Stevens Institute Of Technology | Methods of preparing a surface-activated titanium oxide product and of using same in water treatment processes |
| US7473369B2 (en) * | 2002-02-14 | 2009-01-06 | The Trustees Of The Stevens Institute Of Technology | Methods of preparing a surface-activated titanium oxide product and of using same in water treatment processes |
| US20080017528A1 (en) * | 2002-04-25 | 2008-01-24 | Sud-Chemie Inc. | Scented container with moisture control capacity |
| US20070029400A1 (en) * | 2002-04-25 | 2007-02-08 | Sud-Chemie Inc. | Scented pharmaceutical or neutraceutical vessel |
| US20040069146A1 (en) * | 2002-07-31 | 2004-04-15 | Carter Steven Alan | Adsorptive duct for contaminant removal, and methods |
| US6997977B2 (en) * | 2002-07-31 | 2006-02-14 | Donaldson Company, Inc. | Adsorptive duct for contaminant removal, and methods |
| US7600999B2 (en) * | 2003-02-26 | 2009-10-13 | Align Technology, Inc. | Systems and methods for fabricating a dental template |
| DE10311830A1 (en) * | 2003-03-14 | 2004-09-23 | Ensinger Kunststofftechnologie Gbr | Spacer profile between glass panes in a double glazing structure has an organic and/or inorganic bonding agent matrix containing particles to adsorb water vapor and keep the space dry |
| US6989101B2 (en) | 2003-04-04 | 2006-01-24 | The Clorox Company | Microorganism-removing filter medium having high isoelectric material and low melt index binder |
| US7303683B2 (en) * | 2003-04-04 | 2007-12-04 | The Clorox Company | Microorganism-removing filter medium having high isoelectric material and low melt index binder |
| US20050067341A1 (en) * | 2003-09-25 | 2005-03-31 | Green Dennis H. | Continuous production membrane water treatment plant and method for operating same |
| WO2005061101A1 (en) * | 2003-11-24 | 2005-07-07 | Airsec | Polymeric adsorbing structure |
| US7022274B2 (en) * | 2003-11-25 | 2006-04-04 | Graver Technologies, Llc. | Gas sintered carbon block and method |
| US8167141B2 (en) | 2004-06-30 | 2012-05-01 | Brita Lp | Gravity flow filter |
| US20060032866A1 (en) * | 2004-08-13 | 2006-02-16 | Pechiney Plastic Packaging, Inc. | Plastic dispensing container having reduced moisture penetration and method for same |
| US20060096911A1 (en) * | 2004-11-08 | 2006-05-11 | Brey Larry A | Particle-containing fibrous web |
| US20060254427A1 (en) * | 2004-11-08 | 2006-11-16 | 3M Innovative Properties Company | Particle-containing fibrous web |
| WO2006116533A2 (en) * | 2005-04-27 | 2006-11-02 | Hw Process Technologies, Inc. | Treating produced waters |
| DE102005022862A1 (en) * | 2005-05-18 | 2006-12-14 | Airsec S.A.S | Capsules for inhalers |
| FR2896235B1 (en) * | 2006-01-18 | 2010-04-23 | Airsec | DEHYDRATING CONTAINER COMPRISING A HUMIDITY STATUS INDICATOR |
| US7673757B2 (en) | 2006-02-17 | 2010-03-09 | Millipore Corporation | Adsorbent filter media for removal of biological contaminants in process liquids |
| US20080011163A1 (en) * | 2006-07-17 | 2008-01-17 | Mcclain Michael S | Sorbent porous polymeric composite materials |
| US20110073551A1 (en) * | 2006-09-20 | 2011-03-31 | Omnipure Filter Company, Inc. | Filter modules for improved media utilization and use in generally cylindrical housing |
| WO2008036816A2 (en) * | 2006-09-20 | 2008-03-27 | Hw Advanced Technologies, Inc. | Multivalent iron ion separation in metal recovery circuits |
| EP2076324A2 (en) * | 2006-09-20 | 2009-07-08 | Omnipure Filter Company, Inc. | Filter with improved media utilization and methods of making and using same |
| USD615150S1 (en) | 2007-09-20 | 2010-05-04 | Omnipure Filter Co., Inc. | Filter block for liquid filtration |
| KR101389231B1 (en) * | 2006-11-16 | 2014-04-24 | 멀티서브 테크놀로지스 인코포레이티드 | Clean, compressed sorbent tablets |
| US20080128354A1 (en) * | 2006-11-30 | 2008-06-05 | Hw Advanced Technologies, Inc. | Method for washing filtration membranes |
| WO2008135569A1 (en) * | 2007-05-07 | 2008-11-13 | Airsec | Release agent for scented additives |
| WO2009002447A1 (en) | 2007-06-21 | 2008-12-31 | Gen-Probe Incorporated | Instrument and receptacles for use in performing processes |
| US20090107925A1 (en) * | 2007-10-31 | 2009-04-30 | Chevron U.S.A. Inc. | Apparatus and process for treating an aqueous solution containing biological contaminants |
| US8349764B2 (en) * | 2007-10-31 | 2013-01-08 | Molycorp Minerals, Llc | Composition for treating a fluid |
| EP2096135B1 (en) * | 2008-02-27 | 2012-07-04 | Airsec | Foamable polymer preparations and compositions comprising a foamed polymer and having high and rapid water absorption |
| US8413655B2 (en) * | 2008-06-10 | 2013-04-09 | Micropore, Inc. | Adsorbents and inhalation devices |
| WO2011094296A1 (en) * | 2010-01-26 | 2011-08-04 | Micropore, Inc. | Adsorbent system for removal of gaseous contaminants |
| JP5901641B2 (en) * | 2010-10-06 | 2016-04-13 | セラニーズ アセテート，エルエルシー | Smoke filter for smoking utensils comprising a porous material with carbon particle loading and enclosed pressure drop |
| WO2012051524A1 (en) | 2010-10-14 | 2012-04-19 | Micropore, Inc. | Adsorbent cartridge assembly with end cap |
| US9233863B2 (en) | 2011-04-13 | 2016-01-12 | Molycorp Minerals, Llc | Rare earth removal of hydrated and hydroxyl species |
| WO2013163167A1 (en) | 2012-04-24 | 2013-10-31 | Micropore, Inc. | Durable adsorbent material and adsorbent packs |
| WO2015134981A2 (en) | 2014-03-07 | 2015-09-11 | Molycorp Minerals, Llc | Cerium (iv) oxide with exceptional arsenic removal properties |
| JP2017127860A (en) * | 2016-01-20 | 2017-07-27 | 三ツ星ベルト株式会社 | Manufacturing method of filter molded body |
| US10391473B1 (en) * | 2016-02-20 | 2019-08-27 | Electric Power Research Institute, Inc. | Polymer-protected sorbent |
| KR20220034837A (en) * | 2019-07-12 | 2022-03-18 | 레르 리키드 쏘시에떼 아노님 뿌르 레뜌드 에렉스뿔라따시옹 데 프로세데 조르즈 클로드 | Method for manufacturing high packing composite adsorbent bed, adsorber comprising same, and adsorption-based gas separation using adsorber |
Family Cites Families (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2059983A (en) * | 1932-06-27 | 1936-11-03 | Gen Plastics Inc | Method of coating abrasive particles |
| CH434078A (en) * | 1964-10-22 | 1967-04-15 | Lorillard Co P | Method of manufacturing a filter for a smoking article and apparatus for its implementation |
| US3217715A (en) * | 1965-05-24 | 1965-11-16 | American Filtrona Corp | Smoke filter and smoking devices formed therewith |
| US3396123A (en) * | 1965-12-22 | 1968-08-06 | Universal Oil Prod Co | Method of preparing a catalyst composite |
| US3474600A (en) * | 1967-09-22 | 1969-10-28 | Pittsburgh Activated Carbon Co | Bonded carbon article |
| US3611678A (en) * | 1968-10-03 | 1971-10-12 | American Filtrona Corp | Activated carbon filter |
| US3746655A (en) * | 1969-02-07 | 1973-07-17 | Calgon Corp | Colored activated carbon |
| GB1320337A (en) * | 1969-12-04 | 1973-06-13 | Ici Ltd | Filled ptfe |
| GB1320377A (en) * | 1970-08-12 | 1973-06-13 | British Oxygen Co Ltd | Apparatus for producing glass |
| JPS476040U (en) * | 1971-02-13 | 1972-09-20 | ||
| US3919369A (en) * | 1971-03-08 | 1975-11-11 | American Filtrona Corp | Method of manufacturing a self-contained low pressure drop filter |
| US3715869A (en) * | 1971-03-08 | 1973-02-13 | American Filtrona Corp | Filter |
| US4012131A (en) * | 1975-08-20 | 1977-03-15 | American Optical Corporation | High strength ophthalmic lens |
| DE2550584A1 (en) * | 1975-11-11 | 1977-05-12 | Deutsche Automobilgesellsch | SHAPE-RESISTANT HYDROGEN STORAGE MATERIAL |
| US4061807A (en) * | 1976-02-09 | 1977-12-06 | Shaler Amos J | Adsorbent body and method for making same |
| DE2624639C3 (en) * | 1976-06-02 | 1980-08-07 | Bergwerksverband Gmbh, 4300 Essen | Process for the production of membranes with a specifically adjusted pore system |
| US4210540A (en) * | 1977-06-03 | 1980-07-01 | Whatman Reeve Angel Limited | Improved filter tube |
| US4144171A (en) * | 1977-12-27 | 1979-03-13 | Parker-Hannifin Corporation | Filter block and method of making the same |
| JPS5928447B2 (en) * | 1978-06-12 | 1984-07-13 | 黒崎窯業株式会社 | Refractory manufacturing method and equipment |
| US4315837A (en) * | 1980-04-16 | 1982-02-16 | Xerox Corporation | Composite material for ozone removal |
| EP0056724A3 (en) * | 1981-01-19 | 1982-10-20 | Inco Selective Surfaces, Inc. | Polymeric structure for hydrogen storage |
| DE3211629A1 (en) * | 1982-03-30 | 1983-10-06 | Basf Ag | METHOD FOR STRENGTHENING THE SURFACES OF GRAIN ADSORBENTS |
-
1984
- 1984-08-13 US US06/640,447 patent/US4665050A/en not_active Expired - Lifetime
-
1985
- 1985-08-07 CA CA000488218A patent/CA1257859A/en not_active Expired
- 1985-08-08 GB GB08519972A patent/GB2163064B/en not_active Expired
- 1985-08-08 EP EP85305652A patent/EP0172714A1/en not_active Withdrawn
- 1985-08-13 JP JP60178474A patent/JPS6157240A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006092043A1 (en) * | 2005-03-03 | 2006-09-08 | Queen's University At Kingston | Polymer entrapped particles |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2163064B (en) | 1988-05-25 |
| JPS6157240A (en) | 1986-03-24 |
| EP0172714A1 (en) | 1986-02-26 |
| GB8519972D0 (en) | 1985-09-18 |
| JPH0553541B2 (en) | 1993-08-10 |
| US4665050A (en) | 1987-05-12 |
| GB2163064A (en) | 1986-02-19 |
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