The hydrogenation of fatty oils with palladium catalyst. I. Hydrogenation of castor oil

Summary A good quality of castor wax was prepared in the laboratory at 100°C. and 45 p.s.i.g., using a modified palladium catalyst. The product obtained had an iodine value of 4, a hydroxy value of 145, and acid value of 1.8, and a capillary melting point of 86°.     

The hydrogenation of fatty oils with palladium catalysts. VI. Hydrogenation for margarine

Satisfactory margarine stocks have been made with a palladium on carbon catalyst in laboratory, pilot plant, and plant processing. The catalyst was shown to make a satisfactory product even when, on continued re-use, the ratio of oil to metal used reached 400,000 to 1.     

Selective hydrogenation of soybean oil. II. Copper-chromium catalysts

Soybean oil was partially hydrogenated at 170 and 200C with 0.5 and 0.1% copper-chromium catalysts, respectively. The reaction proceeded selectively at both temperatures, although selectivity was better at the lower temperature. Both commercial and laboratory-prepared catalysts reduced the linolenic acid to less than 1% and with selectivity ratios (K_Le/K_Lo) ranging from 6 to 13. Since stearate did not increase, linoleate selectivity (K_Lo/K_Ol) was extremely high. About 80% or more of the original linoleic acid remained in the hydrogenated products as measured by the alkali-isomerization method. More conjugated dienes were formed at 200 than at 170C.     

Selective hydrogenation of soybean oil with sodium borohydride-reduced catalysts

The reaction of metallic salts in aqueous solution with sodium borohydride produces finely divided metals that are catalytically active for hydrogenation. Salts of nickel, cobalt, palladium and platinum give active catalysts for the selective hydrogenation of soybean oil. Iron and silver salts, when reduced with sodium borohydride, show no activity at 200C and atmospheric hydrogen pressure. The cobalt catalyst produces the least amount of stearate. Incorporation of palladium, platinum, copper or chromium up to 2% enhance the activity of the nickel catalyst. Copper and chromium salts, when reduced together, form catalysts that hydrogenate linolenyl groups in soybean oil seven times more rapidly than linoleyl groups. No stearate formation is observed with these binary catalysts. Presented at the AOCS Meeting, Houston, April 1965. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Continuous slurry hydrogenation of soybean oil with nickel catalysts

Soybean oil was hydrogenated continuously in the presence of nickel catalysts. The iodine value of the products was varied by changing the oil flow rate and temperature of the reaction. Sulfur-promoted nickel catalyst increased the selectivity for linolenate hydrogenation, but formed much higher proportions oftrans isomers. Linoleate selectivity improved with temperature with both nickel and sulfur-promoted nickel catalysts, buttrans isomerization also increased. The feasibility of this continuous reactor system was demonstrated as a practical means to prepare hydrogenated stocks of desired composition and physical characteristics at high throughput.     

Selective hydrogenation of soybean oil. VI. Copper-on-silica gel catalysts

The preparation of copper-on-silica gel catalysts containing 15% and 20% copper is described. These catalysts can be reused three times without appreciable loss of activity. Their activity compares favorably with the highly active 5% copper-on-silica gel catalyst previously reported. Higher copper catalysts are somewhat less selective for the reduction of linolenate in soybean oil than 5% copper-on-silica gel, but these copper catalysts have greater activity, better reuse characteristics, and selectivity comparable to commercial copper-chromite catalysts. No. Mark. and Nutr. Res. Div., ARS, USDA.     

Catalysts for selective hydrogenation of soybean oil. III. Hydrogenation catalysts prepared on molecular sieves and other supports

A survey of nickel, platinum and palladium catalysts prepared on silicas, aluminas and mo-lecular sieves indicated that the nature of such supports contributed importantly to selective hydrogenation of soybean oil. Nickel-molecular sieve catalysts provided both high hydrogenation selectivity and lowtrans- isomer formation. Some kind of spatial hindrance may be postulated in explanation of the results. Presented at the AOCS Meeting, Toronto, 1962.     

Hydrogenation of soybean oil with copper catalysts containing small amounts of nickel catalysts

Reaction rates, linolenate/linoleate reaction selectivity,trans formation, and conjugated diene formation were determined for mixed commerical catalysts containing 0.5, 1, 2, 10, and 20 parts nickel catalyst (25% nickel) per 1000 parts copper chromite catalyst (ppt) and at catalyst concentrations in the oil of 1.0, 0.5, and 0.25%. The rate of hydrogenation increased as the amount of nickel increased. Addition of 0.5, 1, and 2 ppt nickel catalyst to copper chomite catalyst resulted in a small decrease in selectivity compared with straight copper chromite. When soybean oil was hydrogenated with these mixed catalysts sufficiently to reduce linolenate to 0, iodine values were 102–108 compared to 109–112 for straight copper chromite and to less than 80 for straight nickel. Presented at the AOCS Meeting, New Orleans April 1973. ARS, USDA.     

Hydrogenation of fatty oils with palladium catalysts. V. Products of the tall oil industry

Conditions were found for reducing tall oil distillate to an iodine number of 22 with a sufficiently small amount of palladium catalyst to make the process commereially feasible. The operating conditions were 200°C and 2,600 psi. Tall oil fatty acids were reduced with palladium and the concentration of linoleic acid,cis-oleic acid, saturated acid, andtrans isomers were determined as a function of iodine number. The five-platinum group metals (Pt, Pd, Ir, Rh, Ru) were compared as to activity, selectivity of partial hydrogenation, and tendeney to formtrans-isomers.     

Homogenous catalysis in the reactions of olefinic substances. V. Hydrogenation of soybean oil methyl ester with triphenylphosphine and triphenylarsine palladium catalysts

Some palladium complexes containing coordinated triphenylphosphine or arsine have been found to be effective and selective catalysts in the homogeneous hydrogenation of soybean oil methyl ester. The characteristic features of the catalysis are 1) isomerization ofcis double bonds totrans double bonds, 2) migration of isolated double bonds to form conjugated dienes, 3) selective hydrogenation of poly olefines to mono olefines without hydrogenation of mono olefine, 4) ester exchange of methyl ester to butyl ester, 5) effective hydrogenation and isomerization by methanol in the absence of elemental hydrogen. The catalytic activity of a variety of palladium complexes decreases in the following order: (ϕ₃P)₂PdCl₂+SnCl₂·2H₂O>(ϕ₃P)₂PdCl₂+GeCl₂>(ϕ₃P)₂Pd(CN)₂> (ϕ₃As)₂Pd(CN)₂>(ϕ₃P)₂PdCl₂≫(ϕ₃As)₂PdCl₂. However, neither K₂PdCl₄ with SnCl₂·2H₂O nor (ϕ₃P)₂Pd(SCN)₂ was effective for hydrogenation. The hydrogenation and isomerization of soybean oil methyl ester have been examined under various conditions using a mixture of (ϕ₃P)₂PdCl₂ and SnCl₂·2H₂O. Under nitrogen pressure, in benzene and methanol as a solvent, both isomerization and hydrogenation of soybean oil methyl ester proceeded less effectively than under hydrogen pressure. This work was done under contract with the USDA. Earlier articles in the series are: I, Inorg. Chem.4, 1618 (1965): II, Proceedings of the Symposium on Coordination Chemistry (Tihany, Hungary, 1964), Edited by M. T. Beck, Budapest, 1965; III, JAOCS43, 337 (1966); IV, Advances in Chemistry Series, American Chemical Society, in press.     

Selective hydrogenation of soybean oil: XI. Trialkyl silane-activated copper catalysts

Addition of triethyl silane to copper stearate resulted in an active heterogenous catalyst for the hydrogenation of soybean oil. The linolenate selectivity of this catalyst (K_Le/K_Lo=2.4 to 3.9) was much lower than that obtained with copper chromite (8.4). Unlike copper-chromite catalyst, triethyl silane-activated copper formed stearate during hydrogenation. Both silica and alumina increased catalyst activity. Linolenate selectivity improved slightly in the presence of alumina.     

Catalysts for selective hydrogenation of soybean oil.1 II. Commercial catalysts

A survey of commercial hydrogenation catalysts demonstrated the higher selectivity (S_L= 2.4\s-2.7) of certain platinum, palladium and rhodium catalysts for hydrogenating linolenic components in soybean oil. Nickel catalysts generally showed selectivities below S_L=2.0 although skeletal nickel achieved higher values.Trans-isomers were in the range 7.8\s-15.4% for the above noble metal catalysts. Nickel catalysts provide a lesser degree of isomerization, 5.2\s-7.4% oftrans-isomers for the most selective catalysts. Presented at the AOCS Meeting at Toronto, 1962.     

Fixed- Bed continuous hydrogenation of soybean oil with palladium- Polymer supported catalysts

To compare a continuous hydrogenation system with batch hydrogenation, soybean oil was treated with Pd and Ni catalysts in a fixed-bed system under conditions that gave trickle flow. The influence of processing variables such as space velocity, pressure, temperature and hydrogen flow on the selectivity, specific isomerization and the activity was investigated. Both the Pd and Ni catalysts gave significantly lower specific isomerization(trans isomer per drop in Iodine Value) when compared to reported values for batch hydrogenation with similar type catalysts. The linolenate and linoleate selectivities were also significantly lower. Heterogenized homogeneous Pd-on-polystyrene catalyst gave lower specific isomerization formation and higher selectivity than carbon-supported Pd catalyst at same conditions. This work indicates that Pd-on-styrene, Pd-on-carbon and extruded Ni catalysts, in fixed-bed continuous hydrogenation can produce soybean oil of desirable composition after further optimization.     

Selective hydrogenation of soybean oil: IV. Fatty acid isomers formed with copper catalysts

Two samples of soybean oil hydrogenated with copper-containing catalysts at 170 and 200 C were analyzed for their natural and isomeric fatty acids. Methyl esters of the hydrogenated oils were separated into saturates, monoenes, dienes and trienes by countercurrent distribution between acetonitrile and pentane-hexane. Monoenes were further separated intocis- andtrans-isomers on a silver-saturated resin column. Double bond location in these fractions was determined by a microozonolysis-pyrolysis technique. The diene fraction was separated with an argentation countercurrent distribution method, and linoleate was identified by infrared, ozonolysis and alkaliisomerization data. The double bonds in thecis-monoenes were located in the 9-position almost exclusively. However, the double bonds in thetrans-monoene were quite scattered with 10- and 11-isomers predominating. About 86% to 92% of the dienes consisted of linoleate as measured by alkali isomerization. Other isomers identified as minor components includecis,trans andtrans, trans conjugated dienes and dienes whose double bonds are separated by more than one methylene group. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Selective hydrogenation of soybean oil: XII. Trialkyl aluminum-copper stearate homogeneous catalysts

The reaction of copper stearate with triethylaluminum (TEAL) formed a soluble catalyst that promoted the selective hydrogenation of the linolenyl groups in soybean oil. This homogeneous catalyst was more active than copper-chromite. The activity was enhanced by the addition of silica, alumina or titania. Ethyl alcohol accelerated the hydrogenation when it was added in small amounts and retarded hydrogenation when increased amounts were added. More active and, in some cases, more selective catalysts were formed when TEAL was replaced by trialkylaluminum compounds containing longer chain length in the alkyl groups. Among other organometallics tested, diethylmagnesium and diisobutylaluminum ethoxide formed catalysts with activity comparable to heterogeneous catalysts (K_Le/K_Lo=2.8~5.2) was less than that obtained with copper-chromite (12~14), but greater than that of commercially used nickel catalysts (2). Isomerization, as measured by the percentage oftrans isomers formed, was similar to that of heterogeneous copper catalysts (%trans/ΔIV=0.6~0.7). Presented at the AOCS meeting in New Orleans, May 1981.     

Selective hydrogenation of soybean oil in the presence of copper catalysts

Many investigators associate the poor keeping properties of soybean oil with its linolenic acid content. On the other hand the high linoleic acid content is a desired property from a nutritional point of view. We have therefore developed a process for the preferential reduction of the linolenic acid content by selective hydrogenation. Conventional catalysts for the hydrogenation of fats have a rather low selectivity in this respect. When linolenic acid in soybean oil is hardened (e.g., with a nickel catalyst), most of the linoleic acid is converted into less unsaturated acids. It was found that linolenic acid is hydrogenated much more preferentially in the presence of copper catalysts than in that of nickel and other hydrogenation catalysts. At a linolenic acid content of 2%, soybean oil hardened with nickel catalyst contained about 28% linoleic acid, whereas with copper catalyst the hardened soybean oil contained 49% linoleic acid. By means of our process it is possible to manufacture a good keepable oil of, e.g., I.V. 115 and containing 1% linolenic acid and 46% linoleic acid. The storage stability of this product is comparable with that of sunflower-seed oil. A liquid phase yield of 86% is obtained after winterization at 5C for 18 hr. The high selectivity for linolenate reduction of copper catalysts must be ascribed to the copper part of the catalyst. Investigations into the structure of the catalyst indicate that the active center consists of copper metal crystallites; whether these centers are promoted by the carrier or traces of other substances is under investigation.     

An evaluation of commercial nickel catalysts during hydrogenation of soybean oil

The activities of several commercial nickel catalysts were determined by measuring their activation energies. Among these catalysts, G95E, Resan 22, Nysosel 222 and 325, all with low activation energy, were more active than DM3 and G95H, which had higher activation energy. However, the less active catalysts increased the linoleate selectivity of soybean oil during hydrogenation. The yields of bothtrans isomers and winterized oil were higher for the more selectively hydrogenated oil catalyzed by the less active catalysts. In the sensory evaluation, the fractionated solid fat that contained moretrans isomers was lower in flavor scores than the fractionated liquid oil after hydrogenation and winterization of soybean oil.     

Selective hydrogenation of soybean oil. III. Copper-exchanged molecular sieves and other supported catalysts

Copper-chromium catalysts promote selective reduction of linolenyl groups in soybean oil. Since commercially available catalysts possess only moderate activity, more active catalysts were sought. Copper was dispersed on high-surface-area supports, such as silica, alumina, and molecular sieves. These catalysts had varying activities. Precipitation of copper on Cab-O-Sil, a pure form of silica with a large external surface area, gave the most active catalyst. Selectivity ratios (K_Le/K_Lo) for the hydrogenation of soybean oil with these catalysts varied from 4 to 16; a copper-on-Cab-O-Sil catalyst exhibited the greatest selectivity. Improved selectivity and activity were observed when some supports were treated with hydrochloric acid. For example, with a copper-on-Celite catalyst, soybean oil was hydrogenated in 165 min and gave a selectivity ratio of 5.9. Hydrochloric acid treatment of Celite improved the selectivity to 9.9 and reduced hydrogenation time to 54 min. To ensure maximum activity of some of these catalysts, soybean oil should be more thoroughly bleached than is customarily done for nickel hydrogenation. A commercially refined and bleached soybean oil was hydrogenated with a copper-on-Cab-O-Sil catalyst in 18 min. The same oil, re-refined in the laboratory, was reduced in 11.5 min and had the same selectivity ratio of 15.     

Selective hydrogenation of soybean oil: VII. Poisons and inhibitors for copper catalysts

Hydrogenation rates for the catalytic reduction of soybean oil with a copper-on-silica catalyst increased when the oil was re-refined and bleached in the laboratory. Purification of the re-refined and bleached oil by passage through alumina further enhanced hydrogenation rates. Since these observations suggested that poisons were present in the oil, the effect of minor components of soybean oil upon the activity of copper catalysts was investigated. Free fatty acids, monoglycerides, β-carotene, phosphoric acid, sodium soaps, phosphatides, glycerine, choline, ethanolamine, water, pheophytin, and pyrrole all reduced hydrogenation rates when added to the oil. Organic sulfur added to the oil was a more effective catalyst inhibitor than inorganic sulfur added to the gas. Catalyst activity was affected adversely when iron was added to the oil as a soap or when deposited on the catalyst during its preparation. Squalene, copper soaps, and carbon monoxide had no influence on the activity of the catalyst. Aging of soybean oil also had no effect. There was no significant change in either selectivity or formation oftrans or conjugated diene isomer when these additives were added to the oil.     

Acetylene hydrogenation using palladium zeolite catalysts

Catalysts consisting of low concentrations of palladium on several zeolite carriers were used in the hydrogenation of acetylene in low concentrations in the presence of ethylene in high concentrations. The objective was to maximize the conversion to ethylene and minimize further hydrogenation to ethane or oligomerization. Data for the rate of both acetylene disappearance and conversion to oligomers were correlated by simple first-order relationships in hydrogen partial pressure and palladium concentration over a range of temperatures from 24 to 80°C. The relationship between reaction rate and temperature was described by an Arrhenius-type equation with an effective activation energy of 13-14 kcal/g mol. Reaction rates and selectivities for palladium on silicalite and palladium incorporated into ZSM-5 during synthesis compared favorably with a commercial reference catalyst.