Practical aspects of hydrogenation and soybean salad oil manufacture

Most edible oils are hydrogenated in batch-type slurry converters similar in basic design to those employed when the process was first commercialized in 1911. One major company uses a proprietary continuous slurry process. Other novel batch and continuous slurry systems are available but have not enjoyed significant commercial success. Fixed bed hydrogenation has not been seriously investigated but offers intriguing possibilities. Energy economy is assuming ever greater importance in the design of hardening systems. The accelerated growth of hydrogenation since the 1940s parallels the rapid increase in soybean oil use. In part, it reflects the flavor instability of soybean oil caused by its linolenic ester. When this triunsaturate is lowered by hydrogenation to ca. 3%, a high-quality soybean salad oil can be produced. Standard hydrogenation and separation techniques work well. New separation equipment and processes are entering the marketplace.     

Cleaning of coal-derived oils by filtration

With the development of coal liquefaction processes a major task is the removal of solid particles (mineral components, residual insoluble coal and catalyst) from the hydrogenation products. Depending on the characteristics of these products various cleaning methods are under investigation. Thermal methods (distillation, solvent deashing) are preferred for those hydrogenation processes yielding predominantly distillable oils. The separation of solids from the recently developed SRC I processes presents more problems because the percentage of oils is much too low for distillation to be used exclusively for recovering the recycling oil. Therefore, deashing of the SRC I products using solvents within the critical range as well as filtration processes are under development. The Paper describes the different processes under development at the moment and introduces a newly developed candle filter for SRC I filtration. Besides the design of the filter unit, results of filtration tests, handling of the filter cake and production of a filter aid and coke from the residue are described also.     

Partial hydrogenation of linseed oil by a continuous process

Summary Alkali refined linseed oil was partially hydrogenated, using both continuous and batch processes. The continuous process was carried out in a series of Votator machines, using Rufert nickel catalyst, presures up to 145 psig. and temperatures up to 400°F. The continuous hydrogenation of linseed oil under the most selective conditions possible, using the Votator equipment, shows little selectivity between the linolenic and linoleic acid radicals. A pronounced selectivity is observed between oleic and the more unsaturated acid radicals. Under selective conditions of hydrogenation of linseed oil about 31% of the hydrogenated linolenic acid radical is transformed into 9–15 linoleic acid while the remainder of the linolenic acid goes to oleic acid in either one or two steps. Batch hydrogenation yields oils of superior nonyellowing characteristics over comparable oils prepared by the continuous process. The hydrogenated linseed oils were tested in both clear and pigmented alkyds where they displayed superior non-yellowing characteristics over the original linseed oil and, in many instances, over that of soya bean oil. The yellowing of oils and alkyds appears to be a function of both 1) the quantity of fatty acids more unsaturated than oleic present in the oil and 2) the ratio of the quantity of linolenic acid radicals to linoleic acid radicals present. Presented at 21st fall meeting, American Oil Chemists' Society, Chicago, Oct. 20–22, 1947.     

Technologien zur Verarbeitung von Palmöl und dessen Verwendung

Processing and End Uses of Palm Oil In a short introduction, the economic importance of palm oil in the supply of fat for the West European countries, especially, for the Federal Republic of Germany, is emphasized. Furthermore, the properties and composition of oils from various plantations are given. Special conditions of transportation and storage are discussed. Industrial processing of palm oil consists of the following steps:

• Complete refining including degumming, deacidification, thermal bleaching, treatment with bleaching earth, and deodorization
• Hydrogenation
• Interesterification
• Fractionation

Complete refining is essential for the manufacture of all edible products, whereas the last three processes are generally used for the manufacture of special products from palm oil. Thermal bleaching is a characteristic step in the processing of palm oil, by which the carotenoids are destroyed and the oil is decoloured. This operation can be performed at one of the various stages of refining, and by choice, even in conjunction with deodorization or distillative deacidification. The various possibilities are indicated using a block flow diagram and these are critically evaluated with reference to specific processing conditions. The technical equipment required for these processes are described using schematic illustrations. Next to hydrogenation, occasionally carried out as hydrobleaching, the processes, such as interesterification and fractionation, are very significant for the manufacture of finished products and intermediate products from palm oil. Under this aspect the corresponding technologies and their practical applications are discussed. These processes permit wide applications of palm oil and finished as well as intermediate products prepared therefrom in the production of edible oils and fat dressings. A major part of these products are used in shortenings and margarine. Further products are solid fractions from palm oil as substitutes for cocoa butter, liquid fractions as frying oils etc. Typical examples of these applications are given.     

Hydrogenation of fatty acids

Catalytic hydrogenation is a vital process for both the edible fats and oil and the industrial fatty chemical industries. The similarities and differences between the fat and oil and fatty acid hydrogenations in equipment, processing conditions, and catalysts employed are of some importance since both are used in the various operations. Generally, the catalytic hydrogenation of fatty acids is carried out in corrosion-resistant equipment (316SS), whereas for fats and oils while 316SS is desirable, 304SS or even black iron surffice. The speed of hydrogenation varies radically with the content of impurities in both fat and oil and fatty acid feedstocks. Especially detrimental for both hydrogenations are soap and sulfur contaminants, proteinaceous materials left in the oils from poor refining, etc. Fatty acids from vegetable oil soapstocks are especially difficult to hydrogenate. Soybean-acidulated soapstock must usually be double-distilled for good results; cottonseed soapstocks frequently triple-distilled in order that they can be hydrogenated below iodine values of 1. Fatty acid hydrogenation effectiveness is measured by achieveing a low iodine value as fast and as economically as possible. Variables that influence hydrogenation effectiveness are reactor design, hydrogen purity, feedstock quality, catalyst activity and operating conditions.     

Effects of minor compounds on hydrogenation rate of soybean oil

The poisoning effects of minor compounds in soybean oil on the activity of nickel-based catalysts during hydrogenation was investigated. Several soybean oils prepared by different processes were used as the starting oils for hydrogenation. Soybean oil prepared by combining neutralization with degumming and then followed by bleaching leads to a slower hydrogenation rate than an oil prepared by sequential degumming, neutralization and bleaching with activated clay. The selection of bleaching earth used in the bleaching process affected the hydrogenation rate. Soybean oil bleached with neutral clay showed a slower hydrogenation rate. Higher amounts of phosphorus compounds, oxidation products, β-carotene and iron in these oils accounted for the slower hydrogenation rate. Storage of refined and bleached soybean oil greatly affected the hydrogenation rate. An increase in the oxidation products of RB soybean oil during storage was the major reason for the decrease in the hydrogenation rate.     

Prepress-solvent extraction of crambe: First commercial trial run of new oilseed

Commercial-scale equipment was used to process experimentally 36 tons ofCrambe abyssinica seed grown in the western part of the United States to obtain information on the processing of this new oilseed and to determine characteristics of the oil and meal products. The run was carried out for USDA at the Pacific Vegetable Oil Corporation plant at Sidney, Nebraska, February 1964. Process objectives in the study included dehulling, primary oil removal by expeller prepress, secondary oil removal by solvent extraction and control of thioglucosides to obtain good oil quality. A continuous plant operation yielded crude oils and toasted meal that will be compared with similar products from other commercial oilseed processes. Characteristics of the crude oils that have been determined are composition, refining losses and hydrogenation ability. Organoleptic data on the refined, bleached and deodorized oils have been obtained, as well as compositional data on the desolventized-toasted meals. More than 13 tons of meal and 10 tons of oil were prepared. Presented at the AOCS Meeting, Chicago, October 1964. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, USDA.     

Lipase-catalyzed interesterification of oils and fats

Extracellular microbial lipases can be used as catalysts for the interesterification of oils and fats. Use of specific lipases gives products which are unobtainable by chemical interesterification methods. Some of these products have properties of value to the oils and fats industry. The catalysts for enzymatic interesterification are prepared by coating inorganic support materials with the lipases. For batch interesterification reactions, the catalyst particles are activated by addition of a small amount of water and then stirred with a reactant mixture dissolved in petroleum ether. At the end of the reaction period, the catalyst particles are removed by filtration, and the interesterified triglycerides isolated by conventional fat fractionation techniques. The catalyst can be used in subsequent batch reactions. As an alternative to the batch reaction system, continuous enzymatic interesterification processes can be operated by pumping water containg feedstock through a packed bed of activated catalyst.     

Principles and catalysts for hydrogenation of fats and oils

Hydrogenation of vegetable oils has been practiced since the discovery by Normann some 75 years ago and is the major chemical process in the fat and oil industry. Hydrogenation changes a liquid oil to a semisolid fat which has more utility and better flavor stability. The reaction is not a simple saturation of double bonds with hydrogen, but is an extremely complex series of reactions that result in a myriad of products. By control of the reaction conditions, pressure, temperature, agitation, and catalyst type and concentration, the desired product may be obtained. The use of new equipment and methods has produced some understanding of the hydrogenation reactions. This knowledge has allowed the production of better, more consistent products designed for use by the consumer.     

Interchangeability of fats and Oils

The requirement for interchangeability of fats and oils is a result of such factors as availability and cost of raw materials, and the effects of legislation or market preference on product composition. Such changes should not affect the product’s quality or performance. Interchangeability is practiced today in the production of products for human food, animal feed and technical uses, and is frequently controlled by computer. It is necessary fully to identify a product and its essential features whether simply by melting point or a full triglyceride structure. Modern analytical techniques such as NMR, GC, HPLC and DSC have enabled this identification to become a more exact science. The interchange may consist of a simple substitution of one oil or fat for another, or it may be more complex, involving a number of oils and fats and processes. Finally, the nature of the product may be such that it has to be “tailor-made” using sophisticated processes to produce the required triglyceride composition. The unit processes which are employed are blending, hydrogenation, fractionation and interesterification. In the last process the recently published use of enzymes is of particular interest. Problems encountered are mainly concerned with the polymorphism of fats and oils which frequently sets limits on the proportion of a particular fat which can be used. Limits are also imposed by plant processing capacity. Palm and lauric acid oils are particularly important in the context of interchangeability for both edible and technical purposes because of their fatty acid and triglyceride compositions. They provide good examples of usefulness, problems resulting from polymorphism and the difficulties of substitution.     

OPTIMAL DESIGN AND OPERATION OF BATCH PROCESSES

The economical design of continuous chemical processes to produce commodity products has reached an advanced state of development. Modern computer tools are used routinely to simulate and optimize these processes. This is not the case, however, for the manufacture of speciality products which must be made in batch operations. The continuing shift towards the production of higher value-added specialty products by the CPI has stimulated efforts aimed at developing good computer assisted design strategies for batch processes.

This paper discusses the formulation of the problem for the optimal design and operation of batch processes. The batch problem differs from the continuous one in a number of important ways. First, batch plants do not operate at steady state. There are important trade-offs between the processing time and the severity (intensity) of processing in single units. Cycle time and performance trade-offs also exist among the various units in the process. Second, batch plants produce multiple products in many cases. There is often a competition for shared resources (labor, utilities, and equipment) among the various products. This paper presents a hierarchical solution approach for the design and optimization of a batch process. The approach is demonstrated by solving an example problem which illustrates the fundamental economic trade-offs.     

A kinetic study of the electrochemical hydrogenation of ethylene

In this study, we have examined the kinetics of the electrochemical hydrogenation of ethylene in a PEM reactor. While in itself this reaction is of little industrial interest, this reaction can be looked upon as a model reaction for many of the important hydrogenation processes including the refining of heavy oils and the hydrogenation of vegetable oils.To study the electrochemical hydrogenation of ethylene, several experimental techniques have been used including polarization measurements, measurement of the composition of the exit gases and potential step, transient measurements. The results show that the hydrogenation reaction proceeds rapidly and essentially to completion. By fitting the experimental transient data to the results from a zero-dimensional mathematical model of the process, a set of kinetic parameters for the reactions has been obtained that give generally good agreement with the experimental results. It seems probable that similar experimental techniques could be used to study the electrochemical hydrogenation of other unsaturated organic molecules of more industrial significance.     

Die katalytische Herstellung von Zuckeralkoholen und deren Verwendung

Catalytic production of sugar alcohols (polyols) and their application . The article surveys the numerous applications of the principal sugar alcohols sorbitol and xylitol and their world production in 1978. Nowadays, the industrial production of sugar alcohols is almost exclusively by catalytic hydrogenation of the corresponding sugars; thus sorbitol is manufactured by hydrogenation of D-glucose, xylitol by hydrogenation of xylose, and mannitol by hydrogenation of invert sugar or fructose. Some 80% of the world production of sugar alcohols are manufactured in batch suspension processes using Raney nickel catalysts. Apart from the Atlas Powder continuous suspension process employing nickel-carrier catalysts, continuous processes have recently been developed which use Raney nickel and prove more economical owing to the lower catalyst costs. Trickling processes with fixed catalyst continue to play a minor role. Available production capacity based on batch suspension processes can be expanded by process optimization and new catalyst developments. A newly developed special Raney nickel catalyst reduces the specific catalyst consumption by about 50%.     

Continuous ultrasonic hydrogenation of soybean oil. II. Operating conditions and oil quality

In previous work we found that ultrasonic energy greatly enhanced the rate of hydrogenation of soybean oil. We have now investigated parameters of ultrasonic hydrogenation and the quality of the resulting products. Refined and bleached soybean oil was hydrogenated continuously with and without ultrasonic energy at different temperatures, pressures and catalyst concentrations. Flavor and oxidative stability of the oils were compared with a commercially hydrogenated soybean oil. The extent of hydrogenation (ΔIV) was not affected by temperature between 245 and 290 C, but was greater at 106 psig than at 65 psig hydrogen pressure. The ΔIV of hydrogenated oils increased linearly with catalyst concentration from 40 ppm to 150 ppm nickel. At the same catalyst concentration the IV drop was significantly increased when ultrasonic energy was used. By reducing the amount of power supplied to the ultrasonic reactor to 40% of full power, the specific power (watts/ΔIV) was lowered by 60%. Linolenate selectivities and specific isomerization (%trans/ΔIV) remained the same, but linoleate selectivities were lower than for batch hydrogenation under varied operating parameters. Flavor scores were not significantly different, initially or after storage eight days at 60 C, for oils continuously hydrogenated with and without ultrasonic energy. Hydrogenation of soybean oil with ultrasonic energy offers a method to produce good quality products at potentially lower cost than present methods.     

Kinetic relationship of coal hydrogenation,pyrolysis and dissolution

Data are presented concerning the production of gaseous and liquid products from coal. The processes considered include pyrolysis, dissolution in solvent with and without the application of ultrasonic energy, batch hydrogenation, and continuous hydrogenation. The products are compared with respect to both quantity and type. Activation energies are presented and mechanisms discussed. Coal hydrogenation in the presence of an appropriate catalyst shows very great promise as a means of converting coal to liquid and gaseous fuels. Yields of 30% high octane gasoline, 5% diesel oil, 35% high Btu gas, and 30% char, on a weight basis, have been achieved.     

Modification of poorly clinkering coal for use in coking

If coal is modified by the volatile products formed in pyrolysis, high-quality blast-furnace coke may be produced from batch with a smaller proportion of expensive clinkering coal. In such coking, the batch is modified in the coking chamber; its clinkering properties are improved as a result of partial hydrogenation. New parameters are proposed to describe the modification of the batch; the variation in clinkering properties is established as a function of these parameters. The quality of the coke obtained from modified coal batch is assessed. The relationship between coke quality and the batch composition is determined. The formulas obtained may be used to predict coke quality. Tests show that partial hydrogenation improves coke quality     

Displacement of the double bonds during hydrogenation of unsaturated fatty acid methyl esters

Summary The displacement of the double bond of several unsaturated fatty acid methyl esters during hydrogenation with a nickel-kieselguhr catalyst at 180°C. was investigated. The analysis of the dicarboxylic acids (obtained by oxidation of the reaction products with KMnO₄ in acetic acid solution) by means of partition chromatography enabled a reliable semiquantitative determination of the position isomers formed. During hydrogenation of methyl esters of oleic, elaidic, petroselinic, and linoleic acid formation of large amounts of position isomers was proved to occur. Migration of the double bonds in both directions took place but was in all cases strongly pronounced in a direction opposite the ester group. The place and configuration (cis or trans) of the double bonds in the starting material apparently were of little importance in this respect. It follows that hydrogenation of fatty acid esters leads to products which are far more complicated, as is generally known. This is especially of importance with respect to the application of hydrogenated fatty oils in the food industries.     

Coal hydrogenation: Quality of start-up solvents and partially process-derived recycle solvents

The performance of three sets of start-up solvents and one set of partially process-derived recycle solvents was studied in small autoclave coal hydrogenation tests. The start-up solvents were obtained by catalytically hydrotreating anthracene oils or creosote oils. It is shown that this preparation procedure converts polynuclear aromatics and two-ring aromatics to hydroaromatics and, ultimately, to alicyclics. Coal conversions using start-up solvents are found to reach a maximum at intermediate degrees of solvent hydrogenation which is believed to correspond to a maximal abundance of hydroaromatic solvent hydrogen donors. A solvent hydrogen donor index (SHDI), simply derived from ¹H n.m.r. spectral data, was devised and is found to successfully correlate coal conversions obtained using different start-up solvents, especially where N₂ gas rather than H₂ gas is employed in the autoclave tests. A set of partially process-derived recycle solvents were produced in multiple cycle continuous coal hydrogenation experiments. These were tested under relatively severe hydrogenation conditions in the presence of hydrogen gas, using the small autoclave unit. Substantial donation of solvent hydrogen was found to occur and coal conversions to hexane — and toluene-soluble products are found to be a smooth function of the solvent hydrogen donor index. It is concluded that the hydrogen donor capacity of a solvent is a major factor governing coal conversion, especially when the demand for solvent hydrogen is high. The SHDI parameter is useful in rationalizing the behaviour of start-up solvents. Also, at least in the first few cycles of a continuous two stage coal hydrogenation process, the SHDI parameter allows solvent quality to be monitored, and consequently optimized.     

Effectiveness Factor of Partially Wetted Catalyst Particles: Evaluation and Application to the Modeling of Trickle Bed Reactors

Trickle bed reactors are widely used in the petroleum industry, especially when processing heavy petroleum fractions, some of the applications being the hydrodesulfurization and hy-drocracking of heavy or residual petroleum fractions, hydrotreat-hg of lubricating oils, and other hydrogenation processes. In the chemical process industry the use of trickle bed reactors is not so widespread, although reactions such as the selective hydrogenation of acetylene, hydrogenation of alkyl anthraquinone, synthesis of butynediol, and oxidation of liquids with, air or oxygen are carried out. Extensive analysis of the advantages and disadvantages of this type of reactor has been presented in the literature [1-5].