Hydrogenation of methyl oleate in solvents

The hydrogenation of the oleic acid group was investigated with the objective of determining the effect of solvents on the reaction rate and the formation of positional and geometrical isomers. Methyl oleate, either alone or dissolved in one of several solvents, hexane, ethanol,n-butyl ether, or acetic acid, was hydrogenated to an iodine value of about 50 under atmospheric pressure and at 30°C, with palladium-on-carbon and the W-5 form of Raney nickel as catalysts. Hydrogenation with palladium catalyst, with or without solvents, produced 76.6 to 79.1%trans bonds, based on the total double bonds. This is significantly greater than the 67% obtained previously. Hydrogenation products obtained with Raney nickel and solvents contained as little as 20.7%trans bonds at an iodine value of about 50. In two cases thetrans bonds were equal to about one-third the positional isomers. Positional isomers formed extensively when the Raney nickel was used in the absence of solvents and when the palladium catalyst was used. When the Raney nickel and solvents were used large proportions of double bonds were found in the original 9-position. Presented at the 51st Annual Meeting of the American Oil Chemists’ Society, Dallas, Tex., April 4–6, 1960. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Catalytic behavior of ruthenium in soybean oil hydrogenation

Soybean oil was hydrogenated with a carbon‐supported ruthenium catalyst (Ru/C) at 165 °C, 2 bar H₂ and 500 rpm stirring speed. Reaction rates, trans isomer formation, selectivity ratios and melting behaviors of the samples were monitored. No catalytic activity was found for the application of 10 ppm of the catalyst, and significant catalytic activity appeared at >50 ppm of active catalyst. The catalyst concentration had an effect on the reaction rate of hydrogenation, but the weight‐normalized reaction rate constant (k_c) was almost independent of the catalyst concentration at lower iodine values. Ru/C generated considerable amounts of trans fatty acids (TFA), including high amounts of trans 18:2, and also stearic acid, due to its very non‐selective nature. The selectivity ratios were found to be low and varied between 1.12 and 4.32 during the reactions. On the other hand, because of the low selectivity, higher slip melting points and solid fat contents at high temperatures were obtained than those for nickel and palladium catalysts. Another different characteristic of this catalyst was the formation (max 1.67%) of conjugated linoleic acid (CLA) during hydrogenation. Besides, CLA formation in the early stages of the reactions did not change very much with the lower iodine values.     

Stationary catalysts for the continuous hydrogenation of fats

Hydrogenation characteristics of a wide variety of stationary catalysts were studied with an aim to explore their possible use in the continuous hydrogenation of fats. Refined soybean oil was hydrogenated continuously in a vertical flow-through reactor over a fixed bed of catalyst. Catalysts investigated were pelleted products containing Raney nickel, reduced nickel, reduced palladium, and copper chromite, as well as granulated alloys of the Raney type, such as Ni-Al, Cu-Al, Pd-Al, and Cu-Cr-Al, which were activated with alkali. These catalysts offered a wide choice of activity, selectivity, and ability to form geometrical isomers. Pelleted copper chromite and granular Raney copper-chromium were found to be highly selective toward the linolenate moiety of soybean oil, whereas pelleted palladium on carrier, as well as granular Raney nickel, Raney copper, and Raney palladium, though moderately selective, exhibited very high activity even at relatively low temperatures. A unique feature of most of the stationary catalysts was the remarkably high rate of hydrogenation. With most catalysts, the iodine value of soybean oil was reduced by 40–60 units within a reaction period of 2–4 min. The hydrogenated fat was practically free of catalyst particles.     

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.     

High Oleic and Low <Emphasis Type="Italic">Trans</Emphasis> Fatty Acid Formation by an Electrochemical Process

Electrochemical hydrogenation employing a mediator of formate/formic acid resulted in partial hydrogenation of vegetable and soybean oil at 20–40 °C and ambient pressure when palladium supported on alumina was employed as a catalyst. An oleic acid content of 48% with a corresponding iodine value of 81 for the vegetable oil hydrogenated at 20 °C was obtained. The total trans fatty acid content and especially the 18:1 trans fatty acid were found to increase with the reaction temperature and time. Nonetheless, relatively low total trans and 18:1 trans fatty acid (7 and 3.8%, respectively) contents were found when the vegetable oil was partially hydrogenated to achieve an iodine value of 112.     

Positional and geometrical isomerization during partial hydrogenation of trilinolein: A comparison of copper and nickel catalysts

We have compared a nickel with a copper catalyst in the formation of some geometrical and positional isomers during the partial hydrogenation of trilinolein. The copper catalyst was found to produce fewer diene isomers than the nickel catalyst at a comparable iodine value. The copper catalyst produced more monoene isomers however, than did the nickel, particularlytrans monoenes. The distribution of the monoene isomers appeared to obey an equilibrium relationship with each other, independent of both iodine value and reaction conditions. We have presented additional evidence to postulate that copper catalysts hydrogenate polyenoic acids by first conjugating the acids. The selectivity of copper catalysts for triene over diene is probably due to the greater ease of conjugation of the triene.     

Low trans-Fat Spreads and Shortenings from a Catalyst-Switching Strategy

Low trans fatty acid basestocks suitable for blending with liquid oils to make spreads and shortenings are prepared by using a two-step hydrogenation process. The first step uses a nickel catalyst to hydrogenate soybean, canola, high-oleic sunflower, and high-oleic safflower oils to a predetermined iodine value. At this point in the reaction, the second step commenced. Addition of a platinum catalyst at 80 °C and 73 psi hydrogen pressure allowed for hydrogenation to proceed to iodine values of 40–50. These products had 11–18% trans fatty acid content. These were then blended with soybean oil (5–50% basestock) to give products with bulk properties similar to commercial spreads and shortenings but with about one third the levels of trans fat. Names are necessary to report factually an available data: the USDA neither guarantees nor warrants the standard of the product, and the use of the name USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Palladium- catalyzed hydrogenation of soybean oil

The hydrogenation of soybean oil has been studied using charcoal-supported palladium catalysts at hydrogen pressures between ambient and 70 psig and at temperatures between 80 C and 160 C in three types of stirred reactor. The catalysts employed were 1-10% w/w Pd supported on charcoal and represented differing metal placement on the support. The structure of the catalysts was confirmed by metal surface area measurements, transmission electron microscopy (TEM) and electron spectroscopy for chemical analysis (ESCA). Comparative studies also were carried out under similar conditions using samples of commercial nickel catalysts. Palladium catalysts with the metal placed on the exterior of the charcoal support were the most active and selective at ambient pressure, and although palladium catalysts with metal placed within the charcoal pore system became the most active at higher hydrogen pressures, only the former type of catalyst retained high selec-tivity over the whole temperature and pressure range. Palladium catalysts gave rise to moretrans- acids than nickel, particularly under conditions normally em-ployed with the latter, but if diffusion limitation was avoided, especially at lower temperatures, palladium gave lower quantities oftrans- acid than nickel. In addition, the selectivity of a well designed palladium catalyst was superior to that of nickel and its activity was 15-20 times greater. It is concluded that if palladium is deposited on the exterior of the charcoal so that it is accessible to the triglyceride molecules, then its selectivity and activity is superior to that of nickel, even at low temperatures, at which nickel is inactive. This underlines the importance of choosing the correct preparative route to give optimum metal placement, and it is suggested that when previous studies have indicated that palladium is unselective for fat hardening, it is likely that the metal was not dispersed on the exterior surface of the support. Furthermore, whereas nickel is best used under diffusion-controlled conditions because its selectivity is better in the latter situation palladium should be used under diffusion-free conditions, which implies that very careful attention should be paid to the reactor design.     

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.     

Homogeneous catalytic hydrogenation of soybean oil: Palladium acetylacetonate

Soybean oil was hydrogenated with palladium acetylacetonate at 60–170 C, 150 psi hydrogen and 1–60 ppm palladium. The best linolenate selectivity (K_Le/K_Lo=3.5−3.7) was found at 80–120 C. At 120 C palladium acetylacetonate hydrogenated faster than the heterogeneous Pd-on-carbon catalyst.Trans isomerization with the homogeneous catalyst was much higher compared to Pd-on-carbon catalyst. The low activity of the palladium complex at low temperatures was improved with the addition of triethylaluminum. Among other metal acetylacetonates tested only nickel and chromium were mildly active, whereas cobalt and copper were devoid of catalyst activity.     

Catalytic behavior of palladium in the hydrogenation of edible oils

Palladium supported on alumina was used to hydrogenate soybean and canola oil. Previous literature reports indicated that palladium forms moretrans isomers than nickel. At 750 psig, 50 ppm palladium, and at 70 C, only 9.4%trans were formed when canola oil was hydrogenated to IV 74. In general, high pressure and low temperature favored lowtrans formation with no appreciable loss in catalyst activity. The effect of pressure, temperature and catalyst concentration on reaction rate,trans formation and selectivity is presented. A survey of various catalyst supports is discussed. Apparent activation energies of 6.3 to 8.9 kcal/mol were obtained; they are in good agreement with values reported in the literature.     

Hydrogenation to products with IV below 1

The hydrogenation of fatty acids (FA) or fatty acid methyl esters (FAME) is a fundamental process to manufacture basic oleochemicals, like stabilizers and surfactants. These kinds of oleochemicals are used in downstream processes, to obtain products which are easily bio‐degradable, non‐irritant to the skin, and equipped with other favourable characteristics. In principle the FA or FAME are hydrogenated in a reactor under pressure, higher temperature and in the presence of a metallic catalyst, such as nickel or palladium. The process can be controlled in a desired direction by appropriate choice of these parameters to get a product with different degrees of saturation, melting properties and colour. The commonly used process nowadays is a batch process. The hydrogenation reaction is carried out in a loop or stirred reactor, in the presence of a suspended catalyst. After the reaction the catalyst must be removed from the product by an elaborate and time‐consuming filtration. This leads to higher consumption of catalyst. Another concern is that Ni‐soaps can be formed during the process leading to deactivation of catalyst and the presence of nickel in the final product. Therefore the fixed bed method was developed to eliminate these disadvantages. A pilot plant was constructed in which the catalyst is fixed on a carrier matrix and filled into the reactor and a test run was carried out with FA from tallow and FAME from palm oil. The iodine value of < 0.1 in hydrogenated FAME was achieved as required by the industry for the production of surfactants. In the fixed bed hydrogenation for ME nickel catalyst and for FA a palladium catalyst is used. Furthermore catalyst is reused, its consumption is reduced and the formation of byproducts is minimized. The process is characterized by a high reliability, feed flexibility, easy control and high yield.     

Continuous hydrogenation of fats and fatty acids at short contact times1

Continuous hydrogenation of fats and fatty acids using suspended catalysts was studied in a vertical flow reactor packed with Raschig rings. A short time of reactive contact of the fat or the fatty acid with the catalyst and hydrogen is the unique feature of this system. A nickel catalyst used in the hydrogenation of soybean oil gave a reduction of 40-50 iodine value units per min, small amounts oftrans-isorners (10-20%), large proportions of linoleate in unreduced octadecadienoyl moieties (70-80%), and nonselective reduction of polyunsaturated acyl moieties (linoleate selectivity ratio 1-3). Another nickel catalyst, used in the hydrogenation of tallow fatty acids, also gave a reduction of 40-50 iodine value units per min and nonselective reduction of polyunsaturated fatty acids. A copper chromite catalyst used in the hydrogenation of soybean oil gave a reduction of 10-15 iodine value units per min, low levels oftrans- isomers (10-15%), and selective reduction of linolenoyl moieties (linolenate selectivity ratio 4-6). Composition of positional isomers of cis- andtrans-octadecenoyl moieties in partially hydrogenated products obtained both with nickel and copper chromite catalysts reveals that essentially the same mechanisms of isomerization are involved in continuous hydrogenation at short time of reactive contact as in batch hydrogenation. 1The terms “linoloyl” and “linolenoyl” are used throughout to designate9-cis, 12-cis-octadecadienoyl and 9-cis, 12-cis, 15-cis- octadecatrienoyl groups, respectively.     

Hydrogenation of cyclopropenoid fatty acids occurring in cottonseed oil

The hydrogenation of cyclopropenoid acids and their relative reactivities during hydrogenation as compared to linoleic and oleic acids were examined. Pure methyl sterculate and purifiedSterculia foetida oil and its methyl esters, which have a cyclopropene content more than 60 times that of cottonseed oil, were used for the hydrogenation experiments. Nickel, palladium and platinum catalysts were used. The effect of temperature and type of catalyst were demonstrated in a series of hydrogenation experiments of safflower andS. foetida oil mixtures, and methyl oleate and methyl dihydrosterculate mixtures. Partial hydrogenation of methyl sterculate formed as many as twenty compounds in addition to the cyclopropenoid derivatives. Most of these compounds were monounsaturated. The cyclopropene group hydrogenated very readily compared to the 9,12-diene system in linoleate. The cyclopropane group obtained by hydrogenating the cyclopropenoid acids group was quite resistant to further attack by hydrogen and nickel catalyst had little effect. With palladium catalyst, a temperature of 180 C was necessary for the reaction to go to completion. Platinum in acetic acid was a good system for hydrogenolysis of the cyclopropane group at 80 C. Retired.     

Empirical modeling of soybean oil hydrogenation

Empirical hydrogenation models were generated from statistically designed laboratory experiments. These models, consisting of a set of polynomial equations, relate the operating variables of soybean oil hydrogenation to properties of the reaction and of the fat produced. These properties include reaction rate,trans-isomer content and melting point. Operating variables included in the models were temperature, hydrogen pressure, catalyst concentration, agitation rate and iodine value. The effects of catalyst concentration and agitation rate were found to be significant in determiningtrans-isomer content, which in turn influences the melting characteristics of the hydrogenated oil. Pressures above 30 psig were found to have little effect ontrans-isomer content, although pressure was very important in determining reaction rate. Reaction temperature was observed as the most important factor in determining thetrans-isomer content for a given iodine value. Generally, 50 to 60%trans isomer content is predicted by the model for the iodine value range and operating conditions used in this study. Thus, these predictive models can assist in scaling up hydrogenation processes and in determining the optimum operating parameters for running commercial hydrogenation. Presented at the AOCS Meeting, Chicago, May 1983.     

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 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.     

Castor oil dehydration kinetics

The dehydration reaction kinetics of castor oil was investigated with sodium bisulfate-sodium bisulfite mixture (SB-SB) or p-toluenesulfonic acid as catalyst. Reactions were carried out at 210, 220, and 230°C, and a kinetic model was determined for each case. The reactions with SB-SB catalyst at 210 and 220°C and with p-toluenesulfonic acid at 210°C followed second-order kinetics. A first-order rate equation showed the best fit to the experimental data for the reaction with SB-SB at 230°C. p-Toluenesulfonic acid-catalyzed reactions at 220 and 230°C were also first-order reactions. Additionally, some mathematical equations were derived between iodine value, refractive index, viscosity, and reaction time.     

On the topology of highly branched polyethylenes prepared by amine−imine nickel and palladium complexes: the effect of ortho‐aryl substituents

Series of nickel and palladium complexes bearing amine?imine ligands in various ortho‐aryl and backbone positions were prepared and investigated in ethene polymerization. Ethene polymerization initiated by symmetrically ortho‐substituted nickel and palladium amine?imine catalysts is controlled. Mono‐substitution in the ortho‐aryl positions of nickel complexes is not as efficient in protecting centers from chain transfer as di‐substitution. Both the central metal and the size of the ortho‐aryl substituent have a significant effect on the polyethylene (PE) topology. Based on detailed characterization by high temperature SEC‐IR‐η, SEC with multi‐angle laser light scattering and ¹³C NMR data, PEs prepared by nickel amine?imine complexes have a linear rather than dendritic topology. In contrast, palladium amine?imine complexes with small ortho‐aryl substituents at low ethene pressure were shown for the first time to form dendritic PEs with topology comparable to PEs formed by α‐diimine palladium catalyst. © 2018 Society of Chemical Industry     

Hydrogenation of alkali-conjugated linoleate: Isomeric monoene profiles obtained with nickel,palladium and platinum catalysts

Alkali-conjugated linoleate (cis-9,trans-11- andtrans-10,cis-12-octadecadienoate) was hydrogenated with nickel, palladium and platinum catalysts. Thetrans andcis monoenes formed during reduction were isolated, and their double bond distribution was determined by reductive ozonolysis and gas liquid chromatography. About 44–69% of the monoenes were composed of δ¹⁰ and δ¹¹ trans monoene isomers, whereas the δ⁹ and δ¹² cis monoenes amounted to 20–26%. With nickel catalyst, composition of monoene isomers remained the same, even when the hydrogenation temperature was increased. The monoene isomer profiles between nickel and palladium catalysts were indistinguishable. Isomerization of monoenes with platinum catalyst was suppressed at 80 psi. The position of the double bonds in unreacted conjugated diene was always retained, except with nickel at both temperatures and with platinum at 150 C when a slight migration occurred. Geometrical isomerization totrans,trans-conjugated diene was observed in the unreacted diene with nickel (ca. 15% of diene) at both 100 C and 195 C, and with platinum (ca. 7% of diene) at 150 C. ARS, USDA.