US 3792067 A
Description (OCR text may contain errors)
12, 1974 w. A. cooMBEs ETAL 3,793,057
CONTINUOUS HYDROGENATION OF FATTY MATERIALS Filed June 10. 1971 330mm QM.
aEaa u u oomm Richard A. Zovodo John E. Hansen 8 e .D m so R0 m6 A E m M W William A. Singleton Robert R. King BY 772mm ,QjamyaJaaZ/Qz IRTQRNEYS United States Patent O 3,792,067 CONTINUOUS HYDROGENATION OF FA'ITY MATERIALS William A. Coombes, Pittsburgh, and Richard A. Zavada,
Uniontown, Pa., John E. Hansen, Waukegan, Ill., William A. Singleton, Memphis, Tenn., and Robert R. King, Sherman, Tex., assignors to Blaw-Knox Chemical Plants, Inc., Pittsburgh, Pa. Continuation-impart of abandoned application Ser. No 118,222, Feb. 24, 1971. This application June 10, 19.71, Ser. No. 151,887
Int. Cl. Cllc 3/12 US. Cl. 260-409 16 Claims ABSTRACT OF THE DISCLOSURE Continuous hydrogenation of fatty materials by cocurrently flowing an oil to be hydrogenated, having a hydrogenation catalyst dispersed therein, and hydrogen through a pipeline reactor, with the hydrogen being introduced in spaced intervals over the length of the reactor. The hydrogen is introduced in a manner to provide highly turbulent two-phase flow, preferably of the bubble type and in an amount required to provide the desired reduction in Iodine Number. The process provides a uniform and consistent product, with high linoleic acid selectivity.
This application is a continuation-in-part of application Ser. No. 118,222, filed on Feb. 24, 1971, and now abandoned.
This invention relates to the hydrogenation of fatty materials and more particularly to the hydrogenation of oils containing unsaturated acid moieties. Still more particularly, this invention relates to a new and improved process for continuously hydrogenating fatty oils.
The hydrogenation of fatty materials in the presence of catalysts is a common reaction used in a number of industrial operations. In particular, catalytic hydrogenation is employed for the hardening of unsaturated vegetable marine and animal oils and fats, in particular to produce edible products such as margarine, shortenings, and dietary fats. The catalytic hydrogenation of such fats and oils is generally effected in a batch type of operation and the conditions are generally carefully controlled to provide for selective hydrogenation; i.e., saturation of the less unsaturated acid radicals before the more saturated acid radicals begin to react.
Continuous processes for hydrogenating edible oils have been devised, but in general, they have not been amenable to sutliciently wide variation of product properties to be of value to the industry. While these processes, by their continuou nature, manufacture products which are more uniform than those from batch operations, the selectivity of the hydrogenation has to a large degree been a characteristic of the process, subject to little, if any, control by the operator. In general such processes did not produce a uniform or reproducible product. In addition, such prior art processes were not amenable to operation in a manner other than that which provides oleic acid selectivity; i.e., formation of major portions of mono-unsaturated fatty acid radicals. It is known that vegetable oils containing moderate concentrations of tri-unsaturates are unstable to oxidation without the addition of anti-oxidants and develop reverted" flavors even in the presence of such anti-oxidants. It is also known that reduction of 3,792,067 Patented Feb. 12, 1974 'ice the concentration of these tri-unsaturates enhances the stability of the oil. In recent years it has been found that certain saturated analogs and partially saturated fatty acid radicals having high melting points are detrimental to human health; therefore the linoleic acid selectivity of the hydrogenation process is of extreme importance; i.e., the maximum reduction of poly-unsaturated fatty acid radicals to di-unsaturated fatty acid radicals Without the formation of excessive quantities of mono-unsaturated fatty acid radicals.
An object of this invention i to provide a continuous process for hydrogenating unsaturated oils which produces a uniform and reproducible product.
Another object of this invention is to provide a continuous process for hydrogenating unsaturated oils having improved linoleic acid selectivity.
Another object of this invention is to provide a continuous process for hydrogenating unsaturated oils which enables the operator to adjust conditions to obtain maximum or minimum selectivty, depending upon the desired fatty end product.
These and other objects of the invention should be more readily apparent from the following detailed description thereof when read with reference to the accompanying drawings wherein:
The drawing is a simplified schematic flow diagram of an embodiment of the invention.
The objects of this invention are broadly accomplished by providing a process for continuously hydrogenating a fatty material in which the fatty material having a hydrogenating catalyst dispersed therein and hydrogen are continuously passed through an essentially liquid-filled reactor maintained at hydrogenation pressures and temperatures in turbulent two-phase liquid-gas flow. The total hydrogen, in most cases, is introduced in an amount sub stantially corresponding to the amount of hydrogen required to achieve the desired degree of hydrogenation; i.e., desired reduction in iodine value, and this quantity of hydrogen is introduced in spaced intervals along the reactor. The hydrogen introduction is spaced along the reactor in a manner such that further hydrogen is introduced in order to maintain the desired two-phase liquidgas flow. The flow of fatty material through the reactor is a pipeline type of flow; i.e., without back-mixing, whereby each portion of the liquid to be hydrogenated is main tained in the reactor for the same length of time, commonly referred to as plug flow (this term is not to be confused with two-phase plug flow which has a different meaning in the art).
More particularly, the flow of materials in the reaction zone is maintained at velocities high enough so that both the fatty material and hydrogen pass through the reaction zone under conditions of turbulent flow, without external mechanical agitation, i.e., moving mechanical agitation, with the two-phase flow preferably being controlled to provide a bubble type flow, with such velocities being readily attained by passing the hydrogen and fatty material through an elongated passageway, which may be a straight pipe, a coil, or tubular type of reactor. The turbulent flow is influenced by several factors, including: the mas velocity of the liquid phase; the mass velocity of the gas phase; the density of both the gas and liquid; the viscosity of the liquid; and the surface tension of the gas related to the liquid. The flow conditions employed in the process of the present invention are controlled to GL( is greater than 420, pref y Mass fiow liquid G D G Mass flow gas ttaikal" o) 6-3571 A =Area of pipe across section p =DenSity of gas p =Density of liquid 8 =Surfaee tension of the liquid =Viscosity of the liquid The passing ow two phases through a single conduit under condition of turbulent flow can result in several different types of two-phase flow regimes, including stratified flow, slug flow, annular flow, bubble flow, mist flow, plug flow and spray flow, as described by Anderson et al. in Chemical Engineering, December 6, 1965, page 139, et seq. In accordance with the present invention, as hereinabove noted, the two-phase flow regime is preferably of the bubble type, but for some applications the two-phase flow regime may be stratified, slug or plug type two-phase flow.
The hydrogenation conditions of temperature and pressure are within the range of those generally used in the art and the temperature profile along the length of the reactor may be increasing, decreasing or constant. The control of temperature and pressure conditions to provide a particular type of hydrogenation is generally known in the art, and such teachings are also applicable to the present invention, with the process of the present invention, for a given set of conditions, providing improved selectivity and a more uniform and reproducible product. In general, the hydrogenation is effected at temperatures from about 125 C. to about 250 C., preferably at temperatures from about 180 C. to about 220 Q, and at pressures from about 2 atm. to about 9 atm., preferably at pressures from about 3 atm. to about 6 atm. Theresidence time for the hydrogenation is gene'rally from about 2 to about 20 min. and preferably from about 3 min. to about min. In view of the specific process flow conditions employed in the process of the present invention, unlike prior art processes, the properties of the end product are not as sensitive to changes in temperatures and pressures.
The hydrogenation catalyst employed may be any one of the wide variety of hydrogenation catalysts employed in the art and as representative examples of such catalysts there may be mentioned: copper, nickel, platinum, palladium, cobalt, and the like. The catalyst may be unsupported or supported on a support, such as charcoal, silica, kieselguhr, silica gel and the like. The metallic catalyst is generally employed in an amount from about 0.005 to about 0.05%, and preferably from about 0.025 to about 0.035%, by weight, of the material to be hydrogenated and is generally introduced as a suspension in' the material to be hydrogenated.
It is also to be understood that the catalyst may be an oil-soluble hydrogenation catalyst, e.g., as disclosed in U.S. Pat. 3,542,821, which is hereby incorporated by reference.
The hydrogen is preferably added in a total quantity which essentially corresponds to the amount of hydrogen required to produce the selected reduction in Iodine Number, thereby reducing overall costs by eliminating the necessity for hydrogen recycle. It is to be understood, however, that for some operations the hydrogen may be introduced in quantities which exceed those required to produce the desired reduction in Iodine Number, but in general the excess would not exceed 10% of such requirements.
The hydrogen is introduced into the reactor at spaced intervals along the length thereof in quantities to provide the selected flow conditions; i.e., a Baker parameter of a value hereinabove described, the aforesaid flow conditions being achieved without mechanical mixers or agitators. In accordance with a preferred embodiment, the hydrogen introduction along the length of the reactor is effected in a manner such that the total hydrogen concentration at a point immediately after the introduction does not exceed 0.1%, by weight, and preferably does not exceed 0.04%, by Weight. It is to be understood that an increase in the number of points of hydrogen introduction, for a fixed total quantity of hydrogen to be employed, increases the hereinabove described Baker parameter and the overall selectivity of the process, as hereinafter defined. Ideally, the hydrogen concentration in the oil should approach zero; i.e., an infinite number of injection points at which finite amounts of hydrogen are introduced, but practical considerations limit the ability to achieve such ideal conditions. The selection of the number of points of hydrogen introduction, the quantity of hydrogen introduced at each point and the spacing between the points of introduction to provide the desired flow regime, as hereinabove described, is deemed to be within the scope of those skilled in the art from the teachings herein.
The process of the present invention provides excellent linoleic acid selectivity with the selectivity coefficient (K) being defined as follows:
wherein k is the hydrogenation rate for linolenic acid to a linoleic acid; and k is the hydrogenation rate for linoleic acid to an oleic acid.
The selectivity coefiicient achieved with the process of the present invention, for a specific catalyst, is greater than those generally achieved by the prior art processes. Thus, for example, the use of the process of the present invention is capable of achieving, with a nickel catalyst, a selectivity coefiicient in excess of 2.0, and generally in the order of 2.5, which is a considerable improvement in the selectivity coefiicients generally achieved in prior art processes, either batch or continuous, when employing a commercial nickel catalyst.
The starting materials which are hydrogenated in accordance with the present invention are selected from the wide variety of marine, animal and vegetable oils or fats generally employed in the art, and is preferably one of the natural vegetable oils commonly employed in the art, including: rapeseed oil, mustard oil, cottonseed oil, peanut oil, rubber-seed oil, corn oil, Wheat germ oil, soya bean oil, linseed oil, safflower oil, sunflower oil, and the like, 'with soya bean oil being a particularly preferred starting material. It is to be understood that the present invention is not limited to the particularly specified vegetable starting materials in that other fatty materials, e.g., animal fats, such as lard and tallow are Within the spirit and scope of the invention. The starting material may be pretreated, as generally known in the art (degumming, neutralization, bleaching), prior to being hydrogenated in accordance with the process of the invention and since such treatments are well known in the art, no detailed explanation thereof is deemed necessary for an understanding of the invention.
The degree of saturation which is effected by the process of the present invention is dependent on both he starting material and the desired product. The starting materials may have an Iodine Number within the range from about 40 to about 150, more generally from about 85 to about 150, and in producing solid-like products, the hydrogenation is eifected to reduce the Iodine Number by 15 to 65 units to provide a product having an Iodine Number from to 120, and more particularly, from about 20 to about 120. A preferred starting material is soya bean oil, and in general, soya bean oil which has an Iodine Number from about 131 to about 135 is hydrogenated to reduce the Iodine Number by to 65 units to provide a final product having an Iodine Number from 66 to 120.
In accordance with the present invention, final product control is achieved by controlling both the total quantity of hydrogen employed and the flow parameter of the process. The reduction in Iodine Number; i.e., the Iodine Number of the final product, is determined by the total quantity of hydrogen introduced, and the overall composition of unsaturated fatty acid moieties of the product, having the selected Iodine Number, is determined by the flow conditions employed in producing the product. In general, the higher the value of the aforementioned Baker parameter which defines the llow conditions of the process for producing the product of specified Iodine Numher, the more selective the process (higher selectivity coeflicient K) and the lower the melting point of the final product. Accordingly, the use of the process of the present invention permits control of both the Iodine Number and composition of the final product and the selection of the processing conditions to achieve a specified product should be readily apparent to those skilled in the art from the teachings herein.
The hydrogenated products of the present invention are excellent starting materials for the production of edible products, such as shortenings and margarines and are employed for producing such products as generally known in the art.
The continuous hydrogenation process of the present invention may also be employed for the production of salad oil, in which case the starting material; e.g., soya bean oil, is subjected to a small degree of hydrogenation; i.e., reduction of the Iodine Value of from about 15 to about 25 Iodine units, in order to remove the components thereof which are precursors of reverted flavors. The selective nature of the overall hydrogenation process significantly reduces the formation of the higher melting components; i.e., more saturated components, thereby reducing the amount of precipitate formed during winterization and increasing the yield of salad oil. The processing conditions of temperature and pressure and the catalyst are as known in the art and no detailed explanation thereof is deemed necessary for an understanding of the invention.
The invention will be further described with reference to the accompanying drawing which is a schematic flow representation of a continuous hydrogenation process in accordance with the present invention, but it is to be understood that the scope of the invention is not to be limited thereby. It is also to be understood that the various pumps, valves and the like have been omitted from the drawings in order to facilitate the description thereof with the use of such equipments at appropriate places being within the scope of those skilled in the art.
Referring to the drawing, an oil to be hydrogenated is withdrawn from a storage tank, schematically indicated as 10, through conduit 11 and a major portion thereof passed by feed pump 12 through line 13 for subsequent mixing with catalyst, as hereinafter described. A minor portion of the oil is passed through line 14 to a catalyst slur-ry tank 15 wherein a suitable catalyst, such as nickel, is slurried in the oil to prepare a slurry having a pre-determined amount of catalyst. The catalyst slurry is withdrawn from slurry tank 14 through conduit 16 and passed through metering pump 17 for admixture with oil in line 6 18. The oil flow in conduit 13 and the metering pump 17 are controlled to provide the desired concentration 1 of catalyst in the oil.
i a heat exchanger 26, in which the mixture is preheated by indirect heat transfer with hydrogenated product, as hereinafter described. The preheated mixture is withdrawn from the heat exchanger 26 through line 27 and passed through a heat exchanger 28 in which the mixture is heated to the desired hydrogenation temperature by indirect heat transfer with a suitable heat transfer media, such as hot oil.
The preheated oil-catalyst mixture is withdrawn from heat exchanger 28 through line 29 and introduced into the inlet of a liquid-filled pipeline reactor, schematically indicated as 30, along with a controlled amount of hydrogen from line 31. The pipeline reactor 30, as schematically shown, is a serpentine tubular reactor having a plurality of hydrogen injection points, such as one at each of the reverse bends, schematically indicated as 31a, 31b, 31c, 31d, and 31:2. The amount of hydrogen introduced at the reactor inlet and at intervals along the reactor, as herein noted, is controlled to provide a total quantity of hydrogen that corresponds substantially to the quantity of hydrogen required to provide the desired degree of saturation and is also controlled to provide the selected turbulent flow regime within the reactor 30, as hereinabove described, the aforesaid turbulent flow being achieved without mechanical agitation.
The hydrogenated product, including catalyst, is withdrawn from reactor 30 through conduit 32 and fed to a degasser 33 to separate gases therefrom, which are withdrawn through line 30. The degassed product is withdrawn from degasser 33 through conduit 34 and is transferred by pump 35 through conduit 36 to heat exchanger 26 wherein the hydrogenated product heats, by indirect heat transfer, the feed to the reactor 30. The cooled hydrogenated product from heat exchanger 26 is passed through a heat exchanger 38 in which the hydrogenated product is further cooled by indirect heat transfer with a suitable coolant, such as water. The further cooled hydrogenated product withdrawn from heat exchanger 38 is introduced through line 39 into a catalyst filter 40, of a type known in the art, wherein the catalyst is separated from the hydrogenated product. The filtered hydrogenated product, now essentially free of catalyst, is withdrawn from filter 40 through conduit 41 and passed to product storage, schematically indicated as 42.
It is to be understood that the hereinabove described embodiment is only illustrative of a processing scheme which may be employed for effecting the process of the invention and, therefore, numerous modifications of the described embodiment and other processing schemes are included within the spirit and scope of the present invention. Thus, for example, the various heat transfer steps may be effected in a manner other than as described. Similarly, the reactor may be provided with any of a wide variety of temperature control devices to regulate the temperature of the reactor or with turbulence generating devices, such as baflles or the like to generate additional turbulence within the reactor, provided pipeline flow; i.e., no back-mixing, is maintained in the reactor.
The above modifications and others should be apparent to those skilled in the art from the teachings herein.
The invention will be further described with respect to the following examples, but it is to be understood that the scope of the invention is not to be limited thereby.
In the following examples, the linoleic acid selectivity is determined by the use of FIG. 7, appearing in the article Hydrogenation: Principles and Catalysts, R. R. Allen J. Am. Oil Chem. Soc., vol. 45, page 340 A (June 1968). The oleic acid selectivity (the ratio of the hydrogenation rate of linoleic acid to oleic acid to the hydrogenation rate of oleic acid to stearic acid) is calculated by the method of Albright J. Am. Oil Chem. Soc., vol. 42, pages 250-253 (March 1965).
EXAMPLE I The following is an analysis of a soya bean oil feed which is treated in accordance with the process of the invention.
Percent Palmitic acid 10.97 Stearic acid 3.83 Oleic acid 23.47 Linoleic acid 54.08 Linolenic acid 7.65
The soya bean oil feed having 0.05 weight percent nickel catalyst, supported on kieselguhr (NYSEL) suspended therein is passed in pipeline flow through a tubular reactor at a flow rate of 2400 pounds/hr. and hydrogen is passed cocurrently therewith, with 1 pound/hr. of hydrogen being introduced at the inlet to the reactor; 1 pound/hr. at a distance of one-third of the length of the reactor; and 1 pound/hr. at a distance of two-thirds of the length of the reactor, to provide two-phase bubble flow. The reactor temperature is 350 F.; the reactor pressure 5.5 atm.; and the residence time is 3 min.
The reactor product has the following analysis:
Percent Palmitic acid 10.67 Stearic acid 4.88 Oleic acid 37.19 Linoleic acid 43.60 Linolenic acid 3.66 Iodine Number--1l6.
The linoleic acid selectivity (K) is 2.5.
The oleic acid selectivity (K is 25.
EXAMPLE II The soya bean oil feed of Example I having 0.05 weight percent nickel catalyst, supported on kieselguhr (NYSEL) suspended therein is passed in pipeline flow through a tubular reactor at a flow rate of 2400 pounds/ hr. and hydrogen is passed cocurrently therewith, with 1 pound/hr. of hydrogen being introduced at the inlet to the reactor; 1 pound/hr. at a distance of one-third of the length of the reactor; 0.5 pound/hr. at a distance of one-half of the length of the reactor; and 0.5 pound/hr.
The linoleic acid selectivity coefficient (K) is 2.5. The oleic acid selectivity coeflicient (K is 50.
EXAMPLE III The soya bean oil feed of Example I having 0.05 weight percent nickel catalyst, supported on kieselguhr (NYSEL) suspended therein is passed in pipeline flow through a tubular reactor at a flow rate of 5500 pounds/ hr. and hydrogen is passed cocurrently therewith at a total flow rate of 22 pounds/hr. with the hydrogen being introduced in equal quantities at five points equally spaced over the length of the reactor to provide two-phase bubble flow. The reactor temperature is 410 F.; the reactor pressure 2.5 atm.
The product is tested at one hour intervals and is found to have, at such intervals, an Iodine Number of 76 and melting point of 87 F., thereby indicating the uniformity of the product produced by the process.
Although the hereinabove examples are specifically directed to a soya bean oil, the overall teachings of the invention are equally applicable to other vegetable oils in addition to marine and animal oils and fats.
The hydrogenation process of the present invention is particularly advantageous in that the process is effected continuously to produce a uniform and consistent product. In addition, the overall processing conditions provide a high selectivity. Furthermore, the process provides the added advantage that there is less isomerization of linoleic acid at selective conditions. In addition, the process may be operated with essentially no excess of hydrogen, thereby reducing overall operating costs. Furthermore, the final product specifications may be readily controlled by varying the quantity and manner of hydrogen introduction.
These and other advantages should be apparent to those skilled in the art from the teachings herein.
Numerous modifications and variations of the present invention are possible in light of the above teachings and, therefore, within the scope of the appended claims the invention may be practiced other than as particularly described.
What is claimed is:
1. A continuous process for selectively hydrogenating a fatty material containing linoleic and linolenic acid, comprrsmg: passing fatty material and hydrogen gas cocurrently and continuously in pipeline flow through a reaction zone maintained at hydrogenation temperature and pressure and in contact with a hydrogenation catalyst; metering hydrogen into said reaction zone in spaced intervals along the reaction zone to provide a two-phase flow regime in the reaction zone without external mechanical agitation in which:
qi is greater than 420, wherein Z G Mass flow liquid L= G Mass flow gas lot.) an" A,,=Area of pipe across section =Density of gas =Density of liquid 6 =Surface tension of the liquid u =Viscosity of the liquid required to provide the desired reduction in Iodine Number.
4. The process as defined in claim 1 wherein the catalyst is a supported nickel catalyst.
5. The process as defined in claim 1 wherein is from 1000 to 8000.
6. The process as defined in claim 1 wherein the hydrogen is introduced along spaced intervals to provide a hydrogen concentration immediately after such introduction which does not exceed about 0.1%, by weight.
7. The process as defined in claim 1 wherein the fatty material is a vegetable oil.
8. The process as defined in claim 1 wherein the hydrogenation temperature is from about 125 C. to about 250 C.
9. The process as defined in claim 1 wherein the hydrogenation pressure is from about 2 atm. to about 9 atm.
10. The process as defined in claim 1 wherein the residence time is from about 2 min. to about 20 min.
11. A continuous process for hydrogenating soya bean oil, comprising: passing the soya bean oil and hydrogen gas cocurrently and continuously in pipeline flow through a reaction zone maintained at hydrogenation temperature and pressure and in contact with a hydrogenation catalyst; metering hydrogen into said reaction zone in spaced intervals along the reaction zone to provide a two-phase flow regime in the reaction zone without external mechanical agitation in which:
g is greater than 420, wherein G Mass flow gas T A Area of pipe across section =Density of gas p =Density of liquid 5 =Surface tension of the liquid un=Viscosity of the liquid and continuously withdrawing hydrogenated product form the reaction zone.
12. The process as defined in claim 11 wherein the hydrogen is introduced in a quantity suflicient to produce a hydrogenated product having an Iodine Number from 66 to 120.
13. The process as defined in claim 11 wherein the hydrogenation catalyst is a nickel catalyst.
14. The process as defined in claim 13 wherein the two-phase flow regime is controlled to provide a selectivity coefiicient K which is in excess of 2.0 wherein k;,,, is the hydrogenation rate for linolenic acid to linoleic acid; and k is the hydrogenation rate for linoleic acid to oleic acid.
15. The process as defined in claim 14 wherein the hydrogen is introduced along the reactor at a rate to provide a hydrogen concentration immediately after such introduction which does not exceed about 0.1%, by weight.
16. The process as defined in claim 15 wherein the hydrogenation temperature is from about C. to about 250 C. and the hydrogenation pressure is from about 2 atm. to about 9 atm.
References Cited UNITED STATES PATENTS 3,423,176 1/1969 Kabisch et al 23288 E 1,333,328 3/1920 Martin 23285 3,444,221 5/1969 Voeste et al. 260409 3,278,568 10/ 1966 De Jonge et al 260-409 OTHER REFERENCES Anderson et al., Chemical Engineering, vol. 72, pp. 139-144 (1965).
Baker, The Oil & Gas Journal, vol. 56, pp. 156, 157, 159, 160, 161, 163, and 167 (1958).
LEWIS GOTTS, Primary Examiner D. G. RIVERS, Assistant Examiner