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.     

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.     

Oxidative stabilities of low-linolenate,high-stearate and common soybean oils

It is generally agreed that the high linolenate (18:3) content of soybean oil (SBO) contributes to its flavor instability. In this study, the oxidative stability of five SBO of various fatty acid (FA) compositions was compared by using peroxide values, conjugated dienoic acid values and sensory panel scores. Three of the oils were from common commercial varieties representing the range of 18:3 content normally found in SBO. The other two oils were from seed developed in a mutation breeding program. One of these oils from the line A5 had an 18:3 content of 3.5%, and the other from the line A6 had a stearate (18:0) content of 24%. Seed from the five soybean varieties was cold pressed, refined and deodorized without additives under laboratory conditions. Two oxidation experiments were conducted. In the first, the oils were stored at 28 C for 67 days. In the second, the oils were stored at 60 C for eight days. Sensory comparisons were done by using the AOCS Flavor Intensity Scale. The A5 and A6 oils were more stable than the commercial varieties as measured by chemical tests, but the sensory data were inconclusive. Oils with similar 18:3 contents did not have similar rates of oxidation. The differences between the oils were not as distinct in the 60 C test as in the 28 C test.     

High-temperature stabilities of low-linolenate,high-stearate and common soybean oils

Four soybean oils (SBO) with different fatty acid (FA) compositions were tested for stability during intermittent heating and frying of bread cubes. None of the oils was hydrogenated or contained any additives. Two of the oils were from common commercial varieties. The other two oils were from seed developed in a mutation breeding program and included the line A5, which contained 3.5% linolenate, and the line A6, which contained 20% stearate. Each oil (450 g) was heated to 185 C in a minifryer. Bread cubes were fried at the beginning of heating, and half were stored at −10 C to preserve freshness. The second half was stored at 60 C for 14 days. Heating was continued for 10 hr/day for four days. After 40 hr of heating, an additional 30 g of bread cubes were fried. According to sensory evaluations of the fried bread cubes, peroxide values of oil extracted from the cubes and conjugated diene values of the oils, the A5 and A6 oils were more stable than those from the commercial varieties. Small differences occurred in the flavor and oxidative stability of the cubes fried after 40 hr of heating the oils. Large differences between A5 and A6 and the commercial varieties occurred after storage of bread cubes for 14 days.     

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.     

Hydrogenation of soybean oil by nickel/silica catalysts in a rotating packed disk reactor

Hydrogenation of soybean oil was carried out by nickel/ silica catalysts in a newly developed rotating packed disk reactor (RPDR). The rotation of a catalyst-filled disk facilitated hydrogen transfer into the liquid phase and mixing in the reactor, resulting in an improved threephase reaction. Performance of RPDR in a batch operation was studied by varying temperature, pressure, nickel concentration in the oil, and disk rotating speed. The overall reaction rate increased with these variables, but the selectivity of linoleic acid was high when the hydrogen transfer controlled the reaction on the catalyst.     

Kinetics of copper-chromite hydrogenation in soybean and linseed oils: Effect of pressure

Although a prime impetus for study of copper catalysts has been the selective reduction of linolenic acid in soybean oil, recent economic developments raise the possibility that hydrogenated linseed oil might be a suitable edible oil. Consequently the effect of two hydrogen pressure levels in soybean and linseed oils on the kinetic pathway and on the final distribution of residual double bonds was investigated. The course of the reaction was studied by removing a sample at intervals corresponding to a small iodine value drop, and constituents were determined analytically. The higher pressure increased the rate of reduction, decreased the concentration of conjugated dienes and somewhat reduced the migration of double bonds. Presented at the AOCS Meeting, Atlantic City, N.J., October 1971. Foreign Research Associate from Lesieur Cotelle Co., Dunkirk, France. N. Market. and Nutr. Res. Div., ARS, USDA.     

Deuteration of methyl linoleate with nickel,palladium, platinum and copper-chromite catalysts

Samples taken during deuteration of methyl linoleate with the title catalysts were separated into saturate, monoene and diene fractions. Monoenes were further separated intocis andtrans fractions. A comparison of the double bond distribution in monoenes with those from hydrogenation of alkaliconjugated linoleate indicated that up to 59% of the linoleate was reduced through a conjugated intermediate with nickel catalyst. The respective percentages for palladium and platinum catalysts were 51 and 23. Copper catalysts have previously been shown to reduce linoleate solely through conjugated intermediates. Copper-chromite catalyst showed infinite selectivity for the reduction of linoleate, because stearate did not form. The decreasing order of various catalysts for the selective reduction was copper-chromite>>>Ni at 195 C>Pd>Ni at 100 C>Pt. Computer simulation of platinum reduction indicated that ca. 20% of the linoleate was directly reduced to stearate through a shunt. Geometrical isomers of linoleate were formed during reduction with all catalysts except copper-chromite. Nickel catalyst formed bothtrans,trans- andcis,trans-isomers, as well as nonconjugatable dienes. These isomers were favored at the higher temperature and deuterium was incorporated into them. Palladium and platinum did not isomerize linoleate to nonconjugatable dienes. Because conjugated dienes are more reactive than linoleate, they were not found in appreciable amounts during reduction. Conjugated dienes were the only isomers formed with copper-chromite catalyst. Deuterium was found in these conjugated dienes, which were also extensively isomerized. As a result of isomerization and exchange during reduction of linoleate-as well as further exchange between deuterium and monoenes-a wide distribution of isotopic isomers in monoenes was found with nickel, palladium and platinum catalysts. Since isomerization of monoenes with copper-chromite is negligible, the isotopic distribution of monoenes must be due to exchange of intermediate conjugated dienes followed by addition. Presented at the AOCS Meeting, Ottawa, September 1972. ARS, USDA.     

Winterization of oils and fats

The process of winterization consists of fractional crystallization of oils and fats followed by the separation of solids to make high quality salad oils. To design a winterization process, the rate of cooling of oil, the temperature of crystallization and the mobility of triglyceride molecules in the oil mass are crucial. These variables play a significant role both in separating the solid fats as distinct crystals and facilitating their filtration from the oil. Thus, the main emphasis in this paper is on the effect of the above variables on the performance of the winterization process. Presented at the AOCS short course held April 21–23 1980, Lake Kiamesha, NY.     

Continuous slurry hydrogenation of soybean oil with copper-chromite catalyst at high pressure

Selective hydrogenation of soybean oil to reduce linolenic acid is accomplished better with copper than with nickel catalysts. However, the low activity of copper catalysts at low pressure and the high cost of batch equipment for high-pressure hydrogenation has precluded their commercial use so far. To evaluate continuous systems as an alternative, soybean oil was hydrogenated in a 120 ft × 1/8 in. tubular reactor with copper catalyst. A series of hydrogenations were performed according to a statistical design by varying processing conditions: oil flow (0.5 L/hr, 1.0 L/hr and 2.0 L/hr), reaction temperature (180 C and 200 C), hydrogen pressure (1,100 psig and 4,500 psig) and catalyst concentration (0.5% and 1.0%). An iodine value (IV) drop of 8–43 units was observed in the products whereas selectivity varied between 7 and 9. Isomerization was comparable to that observed with a batch reactor. Analysis of variance for isomerization indicated interaction between catalyst concentration and hydrogen pressure and between catalyst concentration and temperature. The influence of pressure on linolenate selectivity was different for different temperatures and pressure. Hydrogenation rate was significantly affected by pressure, temperature and catalyst concentration.     

Behavior of hydrogenation catalysts. I. Hydrogenation of soybean oil with palladium

A statistical method for evaluation of catalysts was used to determine the behavior of palladium catalyst for soybean oil hydrogenation. Empirical models were developed that predict the rate,trans-isomer formation, and selectivity over a range of practical reaction conditions. Two target iodine value (IV) ranges were studied: one range for a liquid salad oil and the other for a margarine basestock. Although palladium has very high activity, it offered no special advantage intrans-isomer formation or selectivity. Palladium can substitute for nickel catalyst, at greatly reduced temperature and catalyst concentrations, for production of salad oil or margarine basestock from soybean oil. Presented at the AOCS meeting, Chicago, May 1983.     

Quantification of carbonyl compounds in oxidized low-linolenate,high-stearate and common soybean oils

The carbonyl compounds in five oxidized soybean oils (SBO) of various fatty acid compositions were determined. Three were from common normal soybean varieties, and two were from lines developed from new mutant varieties. One mutant line had a linolenate (18:3) content of 3.5% (A5), and one had a stearate (18:0) content of 24% (A6). SBO were stored at 28 C and 60 C. Trichlorophenylhydrazones (TCPH) of carbonyls formed during oxidation were quantified and tentatively identified by gas chromatography. The storage temperature and the composition of the oils affected the types and amounts of volatiles produced. Hexanal was the major volatile in the oils in both storage tests. After 60 C storage, 2- and/or 3-hexenal was present only in the oil with the highest 18:3 content (BSR 101, 18:3=9%). The amounts of the carbonyls formed in A5 were 2 to 5 times less than the amounts formed in BSR 101. The amounts of many of the carbonyls were converted into relative flavor potency by using reported data. Hexanal was the major contributor to flavor. After storage at 28 C, 2- and/or 3-hexenal was the second most intense flavor compound regardless of the 18:3 content of the oil. The amount of a compound and the threshold value did not always predict its flavor importance according to the flavor potency data.     

Kinetics of hydrogenation of conjugated triene and diene with nickel,palladium, platinum and copper-chromite catalysts

A mixture of methyl linoleate and alkali-conjugated methyl linoleate was reduced with nickel, palladium, platinum and copper-chromite catalysts. The course of hydrogenation was followed by gas liquid chromatography of samples withdrawn at intervals. Relative rate constants of reactants and inermediates were calculated by a computer. Conjugated linoleate was 10–18 times more reactive than methyl linoleate with all catalysts except platinum, which showed no selectivity at 60 C. At 150 C conjugated diene reacted four times faster than methyl linoleate with platinum catalyst. A conjugated diene-to-stearate shunt was observed with palladium and platinum catalysts. When β-eleostearate was hydrogenated with the same catalysts, 50–97% of the triene was reduced directly to monoene with all catalysts except copper chromite, which selectively reduced conjugated triene to conjugated diene. On the basis of present kinetic data and previous knowledge about the mode of hydrogen addition to conjugated systems, a scheme has been proposed to account for the products formed during hydrogenation of methyl linolenate. ARS, USDA.     

Hydrogenation of natural oils with platinum metal group catalysts

Studies in the hydrogenation of natural oils with catalysts of the platinum metals group have been limited mainly to platinum and palladium with only scant attention to rhodium, ruthenium, iridium and osmium. This preference was dictated largely by economics, palladium being the only noble metal catalyst truly competitive on a usecoat basis with nickel in the hydrogenation of low-priced oils. This paper discusses the noble metal catalysts as a group, points out similarities and differences among the metals relevant to the hydrogenation of natural oils, and describes some of the practical applications of catalysis by palladium. One of 10 papers to be published from the Symposium “Hydrogenation”, presented at the AOCS Meeting, New Orleans, April 1970.     

Hydrogenation of oxidized soybean oil

Anderson Clayton Foods, Richardson, TX 75080 Portions of refined and bleached soybean oil were stored at various temperatures for various lengths of time, then hydrogenated to 70 iodine value (IV) to find the effect of peroxides on the rate of hydrogenation and on characteristics of hydrogenated product. Samples were treated up to 3 wk at up to 65°C and provided samples with peroxide values (PV) of up to 358. All samples were analyzed, hydrogenated, and reanalyzed. Peroxides affected the fatty acid composition as determined by gas chromatography, the calculated iodine value based on fatty acid composition, and rate of hydrogenation. Peroxides also affected the selectivity of hydrogenation and slope of the solids curve in hydrogenated products.     

Effect of phospholipid structure on kinetics and chemistry of soybean oil hydrogenation with nickel catalysts

Phospholipids (PL) are one of the compounds which poison nickel catalysts during the hydrogenation process. It was affirmed that even trace amounts of PL (5—10 ppm P) cause a decrease in catalyst activity. Quantities over 50 ppm P almost totally inhibit the reaction. In bleached oils used for hydrogenation, PL exist as native compounds as well as products of their transformation. In the present work, the effect of native phospholipids, lysophospholipids (LPL) and phosphatidic acids (PA) on the kinetics and chemistry of soybean oil hydrogenation was investigated. It was found that PA were more toxic to nickel catalysts than LPL and native PL. Fine‐grained catalyst was more active and resistant to the poisoning effect of phospholipids than moderate‐grained catalyst. No changes in the oil hydrogenation chemistry were observed in the presence or absence of PL; thus, linoleic and linolenic selectivity and specific isomerization did not undergo any change.     

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.     

Hydrogenation of heptaldehyde to heptyl alcohol with nickel catalysts

Hydrogenation of heptaldehyde to heptyl alcohol was studied with W2 Raney nickel catalyst, prepared in the laboratory, commercial Raney nickel catalyst and Rufert nickel catalyst by varying temperature, catalyst concentration, hydrogen pressure and reaction time. The products were analyzed by gas-liquid chromatography on SE-30 column. The optimum conditions found for quantitative conversion (99.6%) of heptaldehyde to heptyl alcohol were: temperature, 100°C, W2 Raney nickel catalyst concentration, 2% based on heptaldehyde (w/w), hydrogen pressure, 145 psig and reaction time, 1 h. IICT Communication No. 3085.