CN102648046B - For preparing the Catalyst And Method of multi-walled carbon nano-tubes - Google Patents
For preparing the Catalyst And Method of multi-walled carbon nano-tubes Download PDFInfo
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Abstract
The present invention provides catalyst precarsor and is applicable to prepare the catalyst of multi-walled carbon nano-tubes.Resultant multi-wall CNT has the tube wall number forming pipe and the pipe diameter of narrow distribution range of narrowly distributing.It addition, the present invention provides produces tube wall number and the method for the narrow multi-walled carbon nano-tubes of diameter Distribution.Further, the present invention provides the compositions of dead catalyst, described dead catalyst to load with many walls nanotube of tube wall and diameter Distribution narrow range.
Description
Background of invention
This application claims and enjoy U.S. Provisional Patent Application the 61/226,438th preferential submitted on July 17th, 2009
Power.The whole of this U.S. Provisional Patent Application the 61/226438th are incorporated herein by reference.
It is known that CNT exists with the structural form of single wall and many walls.Every kind of structure can provide some advantage.
Single-walled nanotube is low due to structural anomaly incidence rate, is therefore preferred for electronic application.But, many walls nanotube typically cost is more
Low, if it is possible to control the quantity of the nanotube walls formed, it is possible in electronic application, provide satisfactory performance.Unfortunate
, the method being currently used for production multi-walled carbon nano-tubes has no ability to control the tube wall of gained in the structure of gained nanotube
Quantity.As a result, the multi-walled carbon nano-tubes diameter prepared at present is typically about 3-35nm, and includes 3-40 concentric graphitic alkene
(graphene) layer, i.e. tube wall.Each layer is the carbon atom cylinder of arranged in co-axial alignment, and its interlamellar spacing is about 0.37nm.Tube wall is with outer
The scope of this wide in range distribution of footpath size limits many walls nanotube for conducting electricity application, heat conduction application and machinery enhancing application
Value.
By contrast, if many walls nanotube has tube wall and the external diameter of relative narrower distribution, then can provide close to
The conductive features of single-walled nanotube.Additionally, many walls nanotube can provide this kind of improvement with lower cost.Further, tube wall number
Measure with many walls nanotube batch of material (btach) of external diameter narrow distribution range compared with the batch of material that distribution is wide, be provided that enhancing
Heat conductivity and mechanical strength.
Although someone multi-walled carbon nano-tubes separation distribution wide from currently manufactured distribution simply may be will recognize that
The multi-walled carbon nano-tubes of narrow range, but the technology realizing this task does not exist.Therefore, present retrievable many walls nanotube
Being entirely provides with undesirable set of wide distribution tube wall and the batch of material of external diameter or batch.
As discussed in detail below, the present invention can provide tube wall and diameter Distribution narrow range many walls nanotube batch
Material.When mixing with thermoplastic, the batch of material of described narrow distribution range can provide that can be equal to single-walled nanotube, ratio is existing
The conductive features that retrievable many walls nanotube batch of material is obviously improved.The present invention also provides for for preparing tube wall and external diameter distribution model
Enclose the Catalyst And Method of narrow many walls nanotube batch of material.
Summary of the invention is summarized
In one embodiment, the invention provides a kind of catalyst precarsor, described catalyst precarsor includes aluminium oxide
(Al2O3), magnesium oxide (MgO) and magnesium aluminate (MgAl2O4) as catalyst carrier.This catalyst precarsor also includes cobalt, ferrum and molybdenum
Metal-oxide.Preferably metal-oxide includes, but is not necessarily limited by the burning of one or more following mixing
Thing: CoFe2O4、CoMoO4、CoxMoO4、Fe2(MoO4)3、CoxFeyMoO4；Wherein x with y represents Co with the Fe atomic ratio relative to Mo,
And x is about 1.6-about 6.5, y is about 0.1-about 10.5.The metal-oxide of the mixing containing two or more metal components is
Preferably, because the oxide of single metal can produce the carbon of carbon fiber and other form.
In another embodiment, the method that present invention provide for preparing catalyst precarsor and catalyst.Described
Method relates to the solution first preparing the metallic compound including following two or more kinds of mixing: selected from cobalt acetate, nitric acid
The cobalt compound of cobalt；Selected from ferric acetate, the iron compound of ferric nitrate；Selected from ammonium heptamolybdate and the molybdenum compound of ammonium dimolybdate；With
And magnesium nitrate.Making this solution react with the aluminium-hydroxide powder of excess, product subsequently forms pastel.Formation pastel is made
Become product to reunite, thus obtain the particle diameter distribution of about 100-1400 micron.Make product be dried subsequently, reduce its size
And roasting, obtain catalyst precarsor.The particle diameter of currently preferred catalyst precarsor is distributed as 70 μm-150 μm.Precursor changes into urges
Agent requires to be placed in the reative cell being suitable as fluidized-bed reactor catalyst precarsor.Noble gas is made to flow through reaction
Room, so that catalyst precarsor to fluidize and to be preheated to required reaction temperature, described noble gas selected from nitrogen, argon or
Helium.When required reaction temperature is issued to limit, replace noble gas with the blend of ethylene and noble gas.
During first contacted with ethylene and noble gas blend is 5 minutes, catalyst precarsor changes into required urging
Agent.In conversion process, the oxide of cobalt and ferrum is reduced into corresponding metal.Additionally, partial oxidation ferrum is reduced into carbon
Change ferrum (Fe3C), molybdenum oxide is reduced into molybdenum carbide (Mo2C)。
Further, the present invention provides the method producing multi-walled carbon nano-tubes, and wherein resultant multi-wall nanotube batch of material is with regard to group
There is narrow distribution for becoming the tube wall number of nanotube, and gained nanotube external diameter also has narrow distribution.Method in the present invention
In, catalyst precarsor is prepared as discussed above.After catalyst precarsor changes into the metallic catalyst of reduction, make second
Alkene/noble gas continues a period of time of flowing under required reaction condition, and the described time should be enough to obtain multi-wall carbon nano-tube
Pipe.Ethylene/noble gas contains the ethylene of about 10-about 80 volume %, and with the enough speed that catalyst pellets sub-bed can be made to fluidize
Degree flowing.The about 10-reaction after date of about 30 minutes, cuts off the air-flow flowing to reative cell, and (carrying) many walls are loaded with in taking-up
The particle of nanotube.The gained carbon product of the about 95-about 98% that useless (spent) catalyst is loaded with is CNT.About 60-is about
The resultant multi-wall CNT batch of material of 90% has 3-6 tube wall, and external diameter is about 3nm-about 7nm.Therefore, the present invention also provides for
Comprising the new product of CNT, described CNT has 3-6 tube wall, and external diameter is about 3nm-about 7nm.
Accompanying drawing explanation
Fig. 1 provides carbon yield and the form of carbon nanotube diameter feature of various carbon monoxide-olefin polymerics on alumina support
Explanation.
Fig. 2 A provides and says corresponding to the figure of the carbon nanotube diameter distribution of the catalyst composition of PXE2-282 in Fig. 1
Bright.
Fig. 2 B provides and says corresponding to the figure of the carbon nanotube diameter distribution of the catalyst composition of PXE2-285 in Fig. 1
Bright.
Fig. 2 C provides and says corresponding to the figure of the carbon nanotube diameter distribution of the catalyst composition of PXE2-288 in Fig. 1
Bright.
Fig. 2 D provides and says corresponding to the figure of the carbon nanotube diameter distribution of the catalyst composition of PXE2-295 in Fig. 1
Bright.
Fig. 3 is that the form of carbon yield and selective impact that reaction temperature and gas form the pipe less on diameter is said
Bright.
Fig. 4 A depicts the carbon nanotube diameter corresponding to SMW-100 carbon nano tube products determined with TEM and is distributed.
Fig. 4 B depicts the carbon nanotube diameter corresponding to MWCNT A carbon nano tube products determined with TEM and is distributed.
Fig. 4 C depicts the carbon nanotube diameter corresponding to MWCNT B carbon nano tube products determined with TEM and is distributed.
Fig. 4 D depicts the carbon nanotube diameter corresponding to MWCNT C carbon nano tube products determined with TEM and is distributed.
Fig. 5 is the figure of the specific insulation of the SMW-100 CNT in Merlon and 3 kinds of business carbon nanotube products
Shape explanation.
Fig. 6 A is the figure explanation of sheet resistance before and after the composite containing nylon 66 resin, and described composite carries
The SMW-100 CNT having born 2.5 weight % or the obtainable multi-wall carbon nano-tube of commercial sources having loaded with 2.5 weight %
Pipe.
Fig. 6 B is the figure explanation of sheet resistance before and after the composite containing nylon 66 resin, and described composite carries
The SMW-100 CNT having born 3.5 weight % or the obtainable multi-wall carbon nano-tube of commercial sources having loaded with 3.5 weight %
Pipe.
Fig. 7 depicts the surface resistivity of the thin film of the CNT including multi-form.
The detailed description of preferred embodiment
Present invention content disclosed in detail below will illustrate catalyst precarsor, prepare the method for catalyst precarsor and by its turn
The method of the catalyst required by chemical conversion.Produce required many walls carbon over the catalyst receive it addition, the invention provides
The method of mitron batch of material, wherein said carbon nano tube products has tube wall and the external diameter of narrow ditribution scope.As in this manual
Used, " carbon content " refers to the percentage ratio of final products based on carbon (CNT+catalyst).So, if 250g is
Finished product is carbon and final products are 500g altogether, then carbon content is exactly 50% or 50.0 (as used by Fig. 1).As at this
Used herein, " carbon yield " refers to the amount relative to carbon product produced by the amount of catalyst used in reaction.It is fixed
Justice is such as below equation: (amount (g) of the amount (g) of carbon/catalyst in final products) x100.Such as, employ 250g catalyst,
The carbon yield of the reaction creating 250g carbon product is 100% ((50g/250g) x100=100%).Such as institute in this manual
Use, (include Fig. 2 A-2D；2A-4D), " frequency (frequency) " refers to that carbon is received in the sample with specified diameter (x-axis)
The quantity of mitron.The most in fig. 2, about 20 diameters are the CNTs of about 6nm.
1. catalyst precarsor and catalyst
The catalyst precarsor of the present invention has the metal-oxide of the mixing being supported on aluminium oxide and magnesium aluminate particle
Surface phase.The metal-oxide of mixing is the oxide containing two or more metal components.It addition, aluminium oxide/magnesium aluminate carries
Body is loaded with the surface of magnesium oxide and is processed.The magnesium oxide that aluminium oxide/magnesium aluminate particle is loaded with is not necessarily embracing layer.MgO and Al2O3
Atomic ratio be about 0.02-0.04.In other words, for the ratio of 0.02: 1, the MgO for each atom has 50 atoms
Al2O3, and when the ratio of 0.04: 1, the MgO of each atom is had to the Al of 25 atoms2O3.As indicated below, these
Part MgO used in calculating can be transformed into MgAl2O4。
The preferred surface of the metal-oxide of mixing includes but not limited to one or more of: CoFe mutually2O4、
CoMoO4、CoxMoO4、CoxFeyMoO4、Fe2(MoO4)3.Typically, metal-oxide provides following weight on catalyst precarsor
The metal of percentage concentration: the Co of about 0.5-about 2.0；The Mo of about 0.3-about 2.0%；The Fe of about 0-about 3.0%.Therefore, for
CoxFeyMoO4, x can be about 1.6-6.5, and y can be 0.1-10.5.It is highly preferred that it is 2.6-that x can be about 3.3 and y
6.3.Under any circumstance, catalyst precarsor all should exist enough metal-oxides, make gained catalyst include following heavy
The metal component of amount percentage ratio: the Co of about 0.5-about 2.0；The Mo of about 0.3-about 2.0%；The Fe of about 0-about 3.0%.At gained
In catalyst, ferrum can be as the metal of reduction or carbide (Fe3C) exist, and molybdenum can be as carbide (Mo2C) exist.
Being preferably based on the weight of catalyst precursor composition, the percetage by weight of every kind of metal component is: Co is about
0.75-about 1.5%；Mo about 0.5-about 1.0%；With Fe about 0.5-about 2.0%.Correspondingly, active metal component is with following atom
Than existing, wherein Mo is that the ratio of definite value: Co with Mo is about 1.6-about 6.5, more preferably from about 2.44-about 4.88, most preferably from about 3.3；
The ratio of Fe with Mo is about 0-about 10.5, more preferably from about 1.75-about 6.98, most preferably from about 2.62-about 6.28.
In catalyst carrier, the existence of Mg ion can reduce the quantity in strong acid site on alumina carrier surface.By reducing
The amount in strong acid site on catalyst support surface, uses the catalyst improved can mainly produce CNT, and produces substantially
The amorphous carbon reduced or other carbon product.As discussed below, the catalytic reaction improving catalyst is used can to produce at least
90%, the CNT of preferably above 98%, using as gained carbon product.
Catalyst precarsor particle diameter preferably from about 20 μm-about 500 μm of the present invention.Preferably, described particle diameter about 20 μm-250 μm.
It is highly preferred that catalyst precarsor particle diameter about 20 μm-about 150 μm.In currently the preferred process discussed below, particle size range is about
70 μm-about 150 μm.
By metal-oxide being reduced to corresponding metal and metal carbides, i.e. Fe °, Fe3C, Co ° and Mo2C, permissible
Catalyst precarsor as above is converted into catalyst particle.Catalyst particle has the gold of existence identical with catalyst precarsor
Belong to atomic ratio.The metallic cobalt of gained nano-scale and the deposit of metallic iron may decide that the Duo Bina produced on catalyst particle
The internal diameter of mitron.Additionally, there are Mo2C dispersibles or separates metallic cobalt, thus avoids the sintering of cobalt, and required by offer
The particle diameter of cobalt.Generally, on carrier, the diameter of gained metal deposit is about 1.5nm-about 3.0nm.Preferably, gained reduced iron and
The deposit diameter of reduction cobalt metal is about 1.5nm-about 2.2nm.It addition, as indicated above, final catalyst particle ratio
The catalyst particle only utilizing aluminum oxide as carrier has less surface acid site.
In a word, the particle diameter of the final catalyst particle of the present invention is about 20 μm-about 500 μm.Preferably, particle diameter is about 20 μ
m-250μm.It is highly preferred that catalyst precarsor particle diameter is about 20 μm-about 150 μm.Many in currently preferred manufacture discussed below
In the method for wall nanotube, it is presently preferred to particle diameter be about 70 μm-about 150 μm.Described catalyst particle comprises:
The most about 91.0-97.6 weight %, the gamma-alumina (γ-Al of preferably from about 94.8-about 97.3 weight %2O3)；
The most about 0.5-about 3.3 weight %, preferred 0.5-1.0 weight % Mg (with MgO and MgAl2O4Form)；
The most about 0.5-about 2.0 weight %, the Co of reduction of preferably from about 0.75-about 1.5 weight %；
The most about 0.3-about 2.0 weight %, the Mo of preferred 0.5-1.0 weight %2The Mo of C-shaped formula；And,
The most about 0-about 3.0 weight %, the reduced iron of preferred 0.5-2.0 weight % and cementite (Fe °, Fe3C) form
Fe。
Typically, can be metal carbides less than the catalyst particle of 2.0 weight %.It is catalyzed for multi-walled carbon nano-tubes
The atomic ratio of reducing metal produced will not great changes have taken place, because producing metallic carbide the most in a large number compared with catalyst precarsor
Thing.
2. the method preparing catalyst precursor particles and catalyst particle
The present invention provides preparation to be applicable to catalysis and forms catalyst precarsor and the method for catalyst of multi-walled carbon nano-tubes.Especially
It is that the catalyst of the present invention can produce the batch of material of the multi-walled carbon nano-tubes of tube wall and diameter Distribution narrow range.
In a preferred embodiment, described method relates to first preparing and comprises following two or more kinds of mixing
The solution of metallic compound: selected from cobalt acetate, the cobalt compound of cobalt nitrate；Selected from ferric acetate, the iron compound of ferric nitrate；Choosing
From ammonium heptamolybdate and the molybdenum compound of ammonium dimolybdate；And magnesium nitrate.Preferably solution include the cobalt acetate in water, ferric nitrate,
Ammonium heptamolybdate and magnesium nitrate.
Unrelated with selected cobalt compound, the concentration of cobalt ions that solution contains is about 20g/L-about 50g/L；Molybdenum ion concentration
It is about 10.5g/L-about 70.3g/L；Iron concentration is about 35g/L-about 105g/L；Further, Mg ion concentration is about 6.7g/L-
About 27.0g/L.The cobalt ion that preferably solution contains is about 26.7g/L-about 40.0g/L；Molybdenum ion is about 17.6g/L-about
35.2g/L；Iron ion is about 52.7g/L-about 70.1g/L；Further, magnesium ion is about 6.7g/L-about 13.5g/L.Most preferably
It is the solution of following ion concentration: cobalt ion is about 33.4g/L；Molybdenum ion is about 17.6g/L；Iron ion is about 63.1g/L；And
And magnesium ion is about 6.7g/L.The formation of the reasonable metal-oxide selecting concentration of metal ions can strengthen required mixing.
It is therefore desirable to provide the metal of reasonable stoichiometric proportion in the solution, to realize this result.
Then metal ion cited above reacts with aluminium hydroxide, obtains metal hydroxides and other ionic compound
Mixture, include but not limited to that stoichiometric proportion can be differently configured from hydroxide shown below: Mg (OH)2, Fe (OH)3、
Co(OH)2、CoMoO4·nH2O、Fe2(MoO4)3·nH2O.The most above-mentioned reaction is at room temperature carried out about 2-4 hour.Reaction
Product has the denseness (consistency) of similar pastel, and this can promote particle aggregation.Preferably, described pastel is aqueous
Amount is about 20-40 weight % water.More preferably pastel contains the water of about 25-about 30 weight %.
If particle aggregation requires, the product of controllable (manipulate) similar pastel, to obtain particle diameter about
The agglomerated particles of 100 μm-about 1400 μm.Generally particle can during reaction be reunited.Preferably, agglomerated particles be about 100 μm-
About 500 μm.In a preferred method, agglomerated particles is being mediated or is being mixed about 20-about 50 minutes in the machine of mixing pastel.Pinch
After conjunction, make product ageing additionally about 2-3 hour.Total time span can be depending on batch sizes.For about 200-about 2000 grams
Batch of material, preferred kneading time is about 30 minutes.Bigger batch of material may require that longer incorporation time.After reunion, to grain
Son is dried and sieves, and separates the particle less than 1400 μm.Preferably, screening step provides the grain of about 100 μm-about 500 μm
Son.
Agglomerated particles is dried the water content to about 10-20 weight % water.Preferably, drying particulate is containing less than 15 weight %
Water.Drying steps is preferably carried out at a temperature of about 30 DEG C-50 DEG C.
Be dried and screening after, at a temperature of about 400 DEG C-600 DEG C at flowing gas under calcine particle about 3 hours-about 8 little
Time time.More preferably calcining step carries out about 3.5 hours-about 4.5 hours at a temperature of about 400 DEG C-500 DEG C.Most preferably
Ground calcining step carries out about 3.5 hours-about 4.5 hours at a temperature of about 440 DEG C-460 DEG C.Preferably, calcined gas is selected from
Air, nitrogen, helium and mixture thereof.Typically, preferred calcined gas is inert gas under calcination condition.It is dried and forges
Burn step and agglomerated particles is decreased to the particle diameter of about 20 μm-about 500 μm.Or, particle sieves before calcination, and if any must
It is ground, so that calcining can produce the particle of 20 μm-250 μm.Preferably, calcining produces the grain of about 20 μm-200 μm
Son.The particle of more preferably from about 20 μm-150 μm.In method for optimizing discussed below, preferred particle size range is about 70 μ
M-about 150 μm.Gained particle is substantially free of water, i.e. moisture is not more than 3 weight %.
Metal hydroxides is changed into corresponding oxide by particle calcining.Such as, hydrated ferric oxide. and molybdate are calcined
To iron molybdate (Fe2(MoO4)3).Similarly, cobalt hydroxide obtains cobalt molybdate (CoMoO with molybdate calcining4).Further, calcining
During Fe (OH)3With Co (OH)2In conjunction with producing CoFe2O4.Finally, Mg (OH)2MgO, aluminium hydroxide (Al is obtained during calcining
(OH)3) change into gamma-alumina, i.e. γ-Al2O3.In calcination process, Mg (OH)2Oxidation still prevents at γ-Al2O3On surface
Form strong acid site.Gained surface structure is considered to be similar to the mixed oxide of Mg-Al-O.Under any circumstance, MgO is loaded with
γ-Al2O3Surface acidity is significantly lower than there is not Mg (OH)2Time calcining γ-Al2O3Surface acidity.
Further, in calcination process, except forming corresponding magnesium and the oxide of aluminum, adjacent with aluminium hydroxide
Divide Mg+2Ion produces parallel reaction.In the reaction, magnesium ion dissolubility in aluminium oxide makes magnesium can replace particle surface
Neighbouring a part of alumina tetrahedra structure, thus produce magnesium aluminate (MgAl2O4), a kind of have similar spinel structure
Compound.Form magnesium aluminate to be better than forming CoAl2O4And FeAlO3.Therefore, this favourable reaction can protect catalytic metal at gained
The catalytic site reduced on carrier particle surface and change into.Especially, the cobalt of reduction obtains nanometer on resulting vehicle surface
The form in particle size territory, ferrum becomes ferrum and the cementite of reduction, and molybdenum becomes molybdenum carbide.The ferrum of cementite and reduction is in catalysis
Disperse described cobalt on agent carrier surface, thus control the internal diameter of gained nanotube.
Gained catalyst carrier has a kind of structure, in this configuration magnesium aluminate be attached to mainly particle outer layer γ-
Al2O3In crystal structure.It addition, MgO is loaded with on the surface of gamma-alumina.Being not only restricted to theory, the MgO on surface is probably and grain
The mixed oxide of sub-aluminium oxide, i.e. Mg-Al-O mixed oxide.This structure by magnesium ion and aluminium oxide in calcination process
Reaction produces.Finally, preferred catalyst carrier is preferably without CoAl2O4And FeAlO3.If there is FeAlO3, then preferably
Catalyst carrier includes the FeAlO less than 0.5 weight %3.If there is CoAl2O4, then preferred catalytic agent carrier includes being less than
The CoAl of 0.5 weight %2O4。
There is magnesium on catalyst carrier particle surface and can reduce the surface acidity of catalyst precursor carrier particle, and gained
Catalyst carrier particle.By reducing the quantity of acidic site on carrier particle surface, the method for the present invention can improve carbon nanometer
The production of pipe, and in the production process of multi-walled carbon nano-tubes subsequently, reduce the formation of other form carbon.Additionally, there are magnesium ion
Stop and form CoAl2O4And FeAlO3, the loss of catalytic metal can be prevented.
After calcining and reducing particle diameter, gained catalyst precursor particles contain through MgO surface process catalyst carrier γ-
Al2O3/MgAl2O4.It addition, the mixed phase of recited metal-oxide is loaded with on the surface of catalyst carrier.As indicated above,
Preferably the metal-oxide of mixing is including but not necessarily limited to CoFe2O4、CoMoO4、CoxMoO4、Fe2(MoO4)3、
CoxFeyMoO4, wherein CoxFeyMoO4For most preferably.
Gained catalyst precarsor is placed in the reaction chamber.Preferably, reative cell is designed to when flowing gas is by this room
And be located therein particle time can produce the fluid bed of catalyst particle.In order to finally catalyst precarsor be changed into catalyst,
Precursor must heat and with the gas reaction of carbon containing.In the following method for producing many walls nanotube, preferred gaseous carbon
Compound is ethylene.Conversion from catalyst precarsor to catalyst occur at a temperature of about 600 DEG C-700 DEG C, with gas carbonization
First of compound contact is during 10 minutes.In this time cycle, metal-oxide is reduced into phase discussed above
Answer metal and metal carbides.It addition, form Fe3C and Mo2C can prevent reduction cobalt and the ferrum sintering on carrier surface and group
Poly-.Therefore, the nanoparticle of the cobalt of gained reduction preferably has the diameter of about 1.5nm-about 3.5nm.It is highly preferred that catalyst
The cobalt metallic of the reduction on carrier surface has the diameter of about 1.5nm-about 2.2nm.Reduced iron particle has similar chi
Very little, the most about 1.5nm-about 3.5nm, preferably from about 1.5nm-about 2.2nm.
Gained catalyst includes the γ-Al processed through MgO surface2O3/MgAl2O4Carrier, and the nanometer on carrier surface
The Fe of size3C and Mo2C particle.The metallic cobalt of reduction can be by γ-Al2O3/MgAl2O4Load with, it is also possible at molybdenum carbide
(Mo2And cementite (Fe C)3C) upper existence.It addition, the ferrum of reduction can be by γ-Al2O3/MgAl2O4Load with, it is also possible in carbonization
Molybdenum (Mo2And cementite (Fe C)3C) upper existence.
As discussed above, the particle diameter of gained catalyst particle is about 20 μm-about 500 μm.Preferably, described particle diameter is about
20μm-250μm.It is highly preferred that catalyst particle size is about 20 μm-about 150 μm.Side at currently preferred manufacture many walls nanotube
In method, it is presently preferred to particle diameter be about 70 μm-about 150 μm.
Catalyst particle includes the gamma-alumina (γ-Al of about 91.0-97.6 weight %2O3), preferably from about 94.8-about 97.3
Weight %；The Mg of about 0.5-about 3.3 weight % is (with MgO and MgAl2O4Form), preferably 0.5-1.0 weight %；About 0.5-is about
The Co of the reduction of 2.0 weight %, preferably from about 0.75-about 1.5 weight %；The Mo of about 0.3-about 2.0 weight %, with Mo2The shape of C
Formula, preferably from about 0.5-about 1.0 weight %；And the Fe of about 0-about 3.0 weight %, with ferrum and cementite (Fe °, the Fe of reduction3C)
Form, preferably 0.5-2.0 weight %.The catalyst particle being typically below 2.0 weight % is metal carbides.For many
The atomic ratio of the reducing metal of wall carbon nano tube catalytic production will not great changes have taken place, because not big compared with catalyst precarsor
Amount produces metal carbides.
In the alternative method for preparing catalyst precarsor, from initial soln, eliminate magnesium nitrate.In the method,
Magnesium hydroxide powder mixes with aluminium-hydroxide powder, and with the solution reaction of metallic compound, described metallic compound includes choosing
From cobalt acetate, the cobalt compound of cobalt nitrate, selected from ferric acetate, the iron compound of ferric nitrate, selected from ammonium heptamolybdate and ammonium dimolybdate
Molybdenum compound, and their mixture.Preferably solution includes the cobalt acetate in water, ferric nitrate, ammonium heptamolybdate and magnesium nitrate.
Unrelated with selected cobalt compound, the concentration of cobalt ions that solution contains is about 20g/L-about 50g/L；Molybdenum ion concentration
It is about 10.5g/L-about 70.3g/L；Iron concentration is about 35g/L-about 105g/L；Further, Mg ion concentration is about 6.7g/L-
About 27.0g/L.The cobalt ion that preferably solution contains is about 26.7g/L-about 40.0g/L；Molybdenum ion is about 17.6g/L-about
35.2g/L；Iron ion is about 52.7g/L-about 70.1g/L；Further, magnesium ion is about 6.7g/L-about 13.5g/L.Most preferably
It is the solution of following ion concentration: cobalt ion is about 33.4g/L；Molybdenum ion is about 17.6g/L；And iron ion is about 63.1g/
L。
Metal ion solution subsequently with the aluminium-hydroxide powder of particle diameter about 20 μm-about 150 μm of excess and particle diameter about 20 μm-
The magnesium hydroxide powder reaction of about 150 μm.After this reaction, the preparation of catalyst precarsor and catalyst subsequently and side as mentioned above
Method is identical.
There is the tube wall of narrow ditribution scope and the manufacture of the multi-walled carbon nano-tubes batch of material of diameter
Following discussion about the catalytic production of multi-walled carbon nano-tubes is substantially relevant catalyst precarsor and catalyst system
Standby continuation discussed above.After being placed in reactor chamber by the catalyst precarsor of calcining, described particle is fluidized and converts
For catalyst particle.As it is indicated above, the particle diameter of catalyst can be about 20 μm-about 500 μm.Preferably, particle diameter is about
20μm-250μm.It is highly preferred that catalyst precarsor particle diameter is about 20 μm-about 150 μm.At currently preferred manufacture many walls nanotube
Method in, it is presently preferred to particle diameter be about 70 μm-about 150 μm.Therefore, described particle is well suited for for fluidized-bed reactor
In.
After being placed in reative cell by catalyst precursor particles, stream of nitrogen gas is made to pass through reative cell, so that particulated bed fluidisation.
Nitrogen is heated to certain temperature, and described temperature should be enough to improve to about 600 DEG C-about 700 DEG C the temperature in fluid bed.Or
Person, reative cell may be located in stove or in other suitable heater.When being positioned in stove, reative cell typically via stove and
Both gas heats.It is highly preferred that fluid bed is previously heated to the temperature of about 600 DEG C-about 650 DEG C.Most preferably, fluid bed is pre-
First it is heated to about 610 DEG C-630 DEG C.It will be understood by those skilled in the art that other non-reacted gas of such as argon or helium
Body can substitute for nitrogen.The major requirement of preheating steps is the fluidisation of fluid bed and is heated to required temperature, the most not
Close the side reaction required.
After temperature stabilization in fluid bed, reactant gas will be transformed into towards the air-flow of described bed from nitrogen.Reactive
Gas is the non-reaction carrier gas containing carbonaceous gas.Preferably carrier gas is nitrogen, and preferred carbonaceous gas is ethylene；But, example
Other carrier gas such as argon or helium also can equally well be worked.Ethylene preferred blends in nitrogen is by volume
About 10-80 volume %.It is further preferred that reactant gas contains the ethylene of about 20-about 50 volume % in nitrogen.Most preferably in nitrogen
Reactant gas containing about 20-about 40 volume % ethylene.
Flow velocity containing ethylene gas is not dependent on the size of reative cell.On the contrary, depended on by the volume of the gas of reative cell
Grams in reative cell inner catalyst precursor.Flow velocity is about every kg catalyst precarsor-about 150L/ minute every kg catalysis in 70L/ minute
Agent precursor.It is highly preferred that flow velocity is about the 90L/ minute every kg catalyst precarsor of every kg catalyst precarsor-about 120L/ minute.
Containing ethylene gas and the primary response of catalyst particle metal-oxide is reduced to its corresponding metal (Co ° and
Fe °) and metal carbides (Mo2C and Fe3C).This reduction step usually occurred in first of course of reaction in 5 minutes.Preferably
Ground, reaction temperature is 600 DEG C-750 DEG C.It is highly preferred that reaction temperature is 610 DEG C-650 DEG C.Most preferably, reaction temperature is
610℃.It addition, in first 10 minutes period of course of reaction, ethylene enters with catalyst precarsor and catalyst particle subsequently
The reaction of row is exothermic reaction.Accordingly, it is preferred that method keeps fluidized-bed temperature less than 670 DEG C.By being lowered into reative cell
The temperature of gas can realize the holding of temperature.If employing stove, then the temperature of stove can also be reduced.Preferably will
Described temperature keeps below 650 DEG C, because higher temperature can cause increasing the amorphous carbon produced.Due to metal-oxide quilt
Reduction, ethylene gas contact gained catalyst particle, and start to grow multi-walled carbon nano-tubes.Metal-oxide is reduced into catalyst particle
After, course of reaction continues about 10-about 40 minutes.It is highly preferred that the course of reaction after metal-oxide reduction proceeds about 15-
25 minutes.
The gained carbon product that spent catalyst particles is loaded with now is 98%, and it is without amorphous carbon and the carbon of other form.
Therefore, the carbon product of 98% is the CNT of many walls.Further, resultant multi-wall CNT mainly has 3-8 tube wall.More excellent
Selection of land, the gained nanotube that spent catalyst particles is loaded with mainly has 3-6 tube wall, and external diameter is about 4.0nm-about 7.0nm.Excellent
Selection of land, the resultant multi-wall CNT of at least 60% has 3-6 tube wall, and external diameter is about 4.0nm-about 7.0nm.More preferably
Ground, the method for the present invention can obtain multi-walled carbon nano-tubes, and the obtained multi-walled carbon nano-tubes of at least a part of which 75% has 3-6 pipe
The required narrow ditribution scope of the diameter of wall and about 4.0nm-about 7.0nm.It is highly preferred that dead catalyst is loaded with at least
The resultant multi-wall CNT of 85% has 3-6 tube wall and the external diameter of about 4.0nm-about 7.0nm.Most preferably, keep continuously
The fluidisation of catalyst particle, the present invention can provide the dead catalyst loading with multi-walled carbon nano-tubes, and the institute of at least a part of which 90% is much
Wall carbon nano tube can have 3-6 tube wall and the diameter of about 4.0nm-about 7.0nm.
Following example and test data are not limiting as the character of the present invention.On the contrary, this information can be strengthened the present invention
Understand.
Embodiment 1
Purpose
The demonstration of this embodiment illustrates that various catalyst metal compositions are on carbon yield and the impact of carbon nanotube diameter.
Method
Prepare various catalyst precarsor to prove the catalytic metal importance to resultant multi-wall product.Fig. 1 table indicates use
In this produced nanotube product compared.For these embodiments, by micro-for the particle diameter 150-300 of preparation as discussed above
600 grams of catalyst precarsors of rice are placed in fluidized-bed reactor.As discussed above, catalyst precarsor is turned by the method for the present invention
Chemical conversion catalyst, and on gained catalyst, grow multi-walled carbon nano-tubes subsequently.For each example provided in Fig. 1,
Whole catalyst at 610 DEG C with nitrogen in 40% ethylene reaction 20 minutes, gas flow rate be 60L/ minute (gas flow/
The mass ratio of catalyst is 100L/ minute every kg catalyst).
Result
As painted in Fig. 1, catalytic metal composition significantly affects resultant multi-wall nanotube product.Such as, test PXE2-282,
PXE2-285, PXE2-292 and PXE2-293 provide with containing Co, Mo and about 0.75 weight % ferrum-about 1.9 weight % ferrum
The relevant data of multi-walled carbon nano-tubes prepared by catalyst.The CNT yield of gained nanotube batch of material is high, wherein position external diameter
Being about 6.72nm-about 8.24nm, mode external diameter is about 4.97nm-about 6nm.The external diameter of these CNTs of 75-85% is less than
10nm.Specifically, PXE2-282 represents many walls nanotube batch of material that mode diameter is 6.0nm, and the median diameter of this batch of material is
8.24nm, and the diameter of this batch of material 73% is less than 10nm.Similarly, to represent mode diameter 5.38nm many for PXE2-285
Wall nanotube batch of material, the median diameter of this batch of material is 6.72nm, and the diameter of this batch of material 85% is less than 10nm.Can be very from Fig. 1
Easily determine the value of PXE2-292 and PXE2-293.During as it is known by the man skilled in the art, term " mode " uses in like fashion
Represent the value that occurrence frequency is the highest in data set.Therefore, for PXE2-285, in this batch of material, nanotube is modal directly
Footpath is 6.72nm.
These results show that described catalyst precursor composition creates the minor-diameter carbon nanotube of very high percentage yield,
Described catalyst precursor composition includes the Co of catalyst precarsor total metal about 0.75-about 1 weight %, the total metal of catalyst precarsor
The Fe of about 0.75-about 1.9 weight %, and the Mo of catalyst precarsor total metal about 0.4-about 0.5 weight %.
By contrast, the catalyst precursor particles lacking ferrum result in significantly reducing of carbon yield.Such as, test PXE2-
288 show, when removing ferrum from cocatalyst formula, and carbon yield losses 57%.It is interesting that products therefrom includes outside middle position
Footpath is 6.98 and mode external diameter is the CNT of 4.68.This hint ferrum is not the reason obtaining minor-diameter carbon nanotube.So
And, result seems to imply that molybdenum serves effect on restriction carbon nanotube diameter.Such as, test PXE2-284 creates outside middle position
Footpath and mode external diameter are respectively the CNT of 9.63nm and 11.06nm.It addition, outside the obtained CNT of only 54%
Footpath is less than 10nm, and testing by contrast in PXE2-285 is 85%, wherein employs Mo in precursor composition.Fig. 2 A-2D
Further illustrate the arbitrary impact on carbon nanotube diameter distribution removing Fe or Mo from catalyst precarsor.In conjunction with rising
Coming, these results show that ferrum serves the effect keeping carbon yield, and molybdenum then can promote to produce the CNT of small diameter.
Embodiment 2
Purpose
With reference to Fig. 3, this embodiment illustrates reaction temperature and gas forms carbon yield and the impact of carbon nanotube diameter.
Method
Use in this experiment and there is in Fig. 1 the carbon monoxide-olefin polymeric of PXE2-282 and PXE2-285 formula as reference.
In order to determine the reaction temperature impact on gained nanotube product, reaction is carried out at a temperature of 610-675 DEG C.Further, this
A little tests determine when in gas material, ethylene concentration changes between 30-40% owing to the change of ethylene concentration is to gained nanotube
The impact of product.
Result
In increasing reaction temperature and/or gas being formed ethylene from 40% be down to 30% time can reduce carbon yield, improve carbon
Tube diameters.Therefore, maximizing for carbon yield and produce minor-diameter carbon nanotube, catalytic reaction should be at about 610 DEG C, and instead
Answering property admixture of gas contains the ethylene of 40%.
Embodiment 3
Purpose
This example compares main containing the answering of minor diameter multi-walled carbon nano-tubes (diameter 4-8nm) with 3-6 tube wall
The electric conductivity of condensation material and the composite including major diameter CNT.This embodiment and embodiment thereafter use according to this
The material (referred to as SMW-100) being designated PXE2-282 in FIG of invention preparation.
Method
By method and the carbon monoxide-olefin polymeric of the present invention, (hereinafter, SMW-100 refers to lead to prepared CNT
Cross the carbon monoxide-olefin polymeric and prepared multi-walled carbon nano-tubes described in Fig. 1 for PXE2-282) and scheme at table 1 with diameter Distribution
The available CNT of various commercial sources described in 4A-D compares.Table 1 below provides various commercial sources
The carbon nanotube diameter distribution of obtainable multi-walled carbon nano-tubes and SMW-100.Such as, for SMW-100,10% nanotube
Diameter is less than 4.2nm, and the diameter of whole nanotubes 50% is less than 6.7nm, and the diameter of whole nanotubes 90% is less than 12nm.
| 10% | 50% | 90% | |
| SMW-100 | 4.2nm | 6.7nm | 12.0nm |
| MWCNT A | 5.5nm | 7.8nm | 13.0nm |
| MWCNT B | 7.4nm | 12.0nm | 16.5nm |
| MWCNT C | 7.1nm | 9.9nm | 13.3nm |
Table 1
Make the CNT source melting mixing described in Merlon Makrolon 2600 PC granule and table 1.Melted mixed
Close under the following conditions at DSM micro-mixing roll (15cm3Carry out in): screw speed-200rpm；Temperature-280 DEG C；Time m-5 points
Clock.Pressing plate (60mm diameter x0.5mm thickness) is prepared from extrusion material strip (temperature: 280 DEG C, time: 1 minute, pressure: 100kN).
Carbon nanotube-sample TGA and tem analysis carry out characterizing (Fig. 4 A-D).
With Keithley 6517A potentiometer, combine Keithley 8009 test fixture (for resistivity ＞ 107Ohm
Or bar formula test fixture is (for resistivity ＜ 10 cm)7Ohm cm) measure resistivity.For the purpose of present disclosure, term
Percolation threshold refers to have in material one and carbon loading concentrations during only one of which continuous print conductive path.
Result
Fig. 5 proves that SMW-100 carbon nano-tube material provides minimum electric percolation threshold.As Fig. 5 describes,
The CNT load of 0.33 weight % can meet the requirement of electric osmose filter.As it is shown in figure 5, for the load of 0.5-1.0 weight %, SMW-
100 provide 104-102The resistivity reading of Ohm/cm.By contrast, diameter is 7-9nm (MWNT A), 10-11nm (MWNT
And the contrast CNT of 12-15nm (MWNT B) respectively obtains 0.50 weight %, 0.50 weight % and 0.55-0.60 weight C)
The percolation threshold of amount %.
Based on the above results, use straight (straight) many walls with the SMW-100 feature that table 1 and Fig. 1 is provided
The batch of material of CNT, can provide more under the load level that multi-walled carbon nano-tubes source more obtainable than other commercial sources is lower
High conductivity performance.
Embodiment 4
Purpose
This research is compared based on the obtainable multi-walled carbon nano-tubes of the commercial sources being dispersed in nylon 66 resin compound
Material, with the performance of composite prepared by the SMW-100 CNT being dispersed in nylon 66 resin.
Method
The mixing of CNT-nylon 6,6 is carried out by twin-screw extrusion.Then gained composite is injection molded into standard
ASTM test bar and test film (4 inches × 4 inches × 3.2 millimeters).Then, on injection molding test film, standard is used
ProStat ohm gauge, carry out conductivity measurement according to the standard ASTM D-257 of volume and sheet resistance.Use PRF-912B
Pop one's head on 25 precalculated positions on each surface of injection-molded plaques, i.e. 25 points on injection-molded plaques front surface and 25 on rear surface
Point measures sheet resistance.Designing this and strictly testing is to have found that material and/or processing the uneven electric property caused
On any minor variations.The front surface of sheet corresponds to push rod location.The rear surface of sheet is corresponding to the fixed part of instrument
Divide (closer to nozzle).Use PRF-911 concentric ring, at the volume resistance of 5 position measurement sheets of each sample, and to sheet
The data of front and rear be averaged.
Result
Fig. 6 A and 6B depicts sheet resistance data.Multi-walled carbon nano-tubes obtainable with commercial sources (MWCNT) phase
Ratio, molded after SMW-100 composite material exhibits go out lower and evenly resistive performance.MWCNT and SMW-100 fills
The sheet resistance ratio of sample more uniform, before and after sheet, surface is the most consistent.
Additionally, based on nylon 6,6 with the composite ratio of SMW-100 based on nylon 6,6 can obtain with commercial sources
The composite of the MWCNT trade mark demonstrate higher conductivity values.SMW-100 composite demonstrates the most further uniformly
Resistance value, the Standard deviation-Range between surface is narrower between test point and before and after sheet.As Fig. 6 A and 6B reflects, by this
The composite of the nanotube preparing the batch of bright carbon nano-tube material, i.e. diameter and tube wall number narrowly distributing uses material phase with existing
Ratio, improves conductivity.
Embodiment 5
Purpose
This example compares the surface resistivity of the thin film containing following nanotube respectively: SMW-100；SWCN
(SWNT)；Double-walled carbon nano-tube (DWNT)；With, the obtainable multi-walled carbon nano-tubes of commercial sources (the MWCNT B of embodiment 3).
Method
Use in 1%Triton-X100 surfactant containing 1g CNT/liter solution, preparation have different thoroughly
The thin film based on CNT of lightness (80-95% transmittance).Solution is then through sonicated and centrifugation.Use rod painting
Method is at PET 505 deposited on substrates various CNT ink.
Result
As shown in FIG. 7, the thin film of the transparency 80-90% prepared with SWNT has other type carbon nanometer than in thin film
The material list of pipe reveals higher electric conductivity.But, use the novel batch material of the present invention, i.e. use SMW-100 to prepare
Thin film, has more preferable conductivity performance than the thin film combining conventional DWNT and MWNT.
According to the enforcement of the present invention disclosed in this specification or this specification, other embodiments of the present invention is for this
Skilled person is apparent from.Therefore, described above is considered as the demonstration of the only present invention, the real model of the present invention
Enclose and should be defined by the following claims with spirit.
Claims (16)
1. a catalyst precursor composition, it comprises:
Carrier；With
The metal-oxide of the mixing on carrier surface, wherein the metal-oxide of this mixing is in following group: Fe2
(MoO4)3、CoxFeyMoO4And their blend, wherein x is 2.44-4.88, and y is 1.75-6.98.
2. the catalyst precursor composition of claim 1, the metal-oxide wherein mixed includes Co3.3Fe2.62MoO4。
3. the catalyst precursor composition of claim 1, the metal-oxide wherein mixed includes Co3.3FeyMoO4And they
Blend, wherein y can be 2.6-6.3.
4. the catalyst precursor composition of claim 1, wherein carrier includes aluminium oxide and magnesium aluminate.
5. the catalyst precursor composition of claim 4, wherein magnesium oxide is positioned on the surface of carrier.
6. the catalyst precursor composition of claim 5, wherein the atomic ratio of magnesium oxide and aluminium oxide is 0.02-0.04.
7. the catalyst precursor composition of claim 5, wherein aluminium oxide is gama-alumina.
8. a catalyst precursor composition, it comprises:
Comprise the carrier of aluminium oxide and magnesium；With
Magnesium oxide on carrier surface and the metal-oxide of mixing, wherein the metal-oxide of this mixing is in following group:
CoxFeyMoO4、Fe2(MoO4)3, and their blend,
Wherein for by CoxFeyMoO4X and y of the metal-oxide of the mixing represented is respectively 1.6-6.5 and 0.1-10.5.
9. the catalyst precursor composition of claim 8, wherein x is 2.44-4.88, and y is 1.75-6.98.
10. the catalyst precursor composition of claim 8, the metal-oxide wherein mixed includes Co3.3Fe2.62MoO4。
The catalyst precursor composition of 11. claim 8, the metal-oxide wherein mixed includes Co3.3FeyMoO4, and they
Blend, wherein y can be 2.6-6.3.
The catalyst precursor composition of 12. claim 8, wherein carrier includes aluminium oxide and magnesium aluminate.
The catalyst precursor composition of 13. claim 12, wherein aluminium oxide is gama-alumina.
The catalyst precursor composition of 14. claim 12, wherein the atomic ratio of magnesium oxide and aluminium oxide is 0.02-0.04.
15. 1 kinds of methods prepared according to the catalyst precursor composition described in claim 1 or 8, comprising:
Preparation comprises the solution of two or more metallic compound, and wherein the metal part of this compound is in following group: cobalt,
Ferrum, molybdenum, magnesium and their mixture；
The solution making metallic compound reacts with aluminium hydroxide, obtains comprising the product of reaction particle；
Drying particulate；
Particle is calcined under flowing gas；And
Reduce the size of particle.
16. 1 kinds of methods prepared according to the catalyst precursor composition described in claim 1 or 8, comprising:
Preparation includes the solution of two or more metallic compound, and wherein the metal part of this compound is in following group: cobalt,
Ferrum, molybdenum and mixture thereof；
Prepare the mixture of aluminium hydroxide and magnesium hydroxide；
Make the mixture of this aluminium hydroxide and magnesium hydroxide and the solution reaction of metallic compound, obtain including the product of reaction particle
Thing；
Drying particulate；
Particle is calcined under flowing gas；And
Reduce the size of particle.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1068325A (en) * | 1991-07-04 | 1993-01-27 | 罗纳布朗克化学公司 | Process for ammoxidation of saturated hydrocarbon |
| CN1465127A (en) * | 2001-07-31 | 2003-12-31 | 爱信Aw株式会社 | Motor manufacturing method |
| CN1495127A (en) * | 1999-06-02 | 2004-05-12 | ����˹���ѧ���»� | Method and catalyst for producing carbon nano tube |
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1068325A (en) * | 1991-07-04 | 1993-01-27 | 罗纳布朗克化学公司 | Process for ammoxidation of saturated hydrocarbon |
| CN1495127A (en) * | 1999-06-02 | 2004-05-12 | ����˹���ѧ���»� | Method and catalyst for producing carbon nano tube |
| CN1465127A (en) * | 2001-07-31 | 2003-12-31 | 爱信Aw株式会社 | Motor manufacturing method |
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