Hydrogenation of oils

These reactors for hquids and liquids plus gases employ small particles in the range of 0.05 to 1.0 mm (0.0020 to 0.039 in), the minimum size hmited by filterability. Small diameters are used to provide as large an interface as possible since the internal surface of porous pellets is poorly accessible to the hquid phase. Solids concentrations up to 10 percent by volume can be handled. In hydrogenation of oils with Ni catalyst, however, the sohds content is about 0.5 percent, and in the manufacture of hydroxylamine phosphate with Pd-C it is 0.05 percent. Fischer-Tropsch slurry reac tors have been tested with concentrations of 10 to 950 g catalyst/L (0.624 to 59.3 IbiTi/fF) (Satterfield and Huff, Chem. Eng. Sci., 35, 195 [1980]). 

The effect of physical processes on reactor performance is more complex than for two-phase systems because both gas-liquid and liquid-solid interphase transport effects may be coupled with the intrinsic rate. The most common types of three-phase reactors are the slurry and trickle-bed reactors. These have found wide applications in the petroleum industry. A slurry reactor is a multi-phase flow reactor in which the reactant gas is bubbled through a solution containing solid catalyst particles. The reactor may operate continuously as a steady flow system with respect to both gas and liquid phases. Alternatively, a fixed charge of liquid is initially added to the stirred vessel, and the gas is continuously added such that the reactor is batch with respect to the liquid phase. This method is used in some hydrogenation reactions such as hydrogenation of oils in a slurry of nickel catalyst particles. Figure 4-15 shows a slurry-type reactor used for polymerization of ethylene in a sluiTy of solid catalyst particles in a solvent of cyclohexane. 

Heterogeneous catalysts have been used industrially for well over 100 years. Amongst the first processes was the catalytic hydrogenation of oils and fats to produce margarine using finely divided nickel. It is quite likely that when this process was first operated in the late nineteenth century unhealthy amounts of nickel remained in the product. The issue of leaching and the avoidance of trace catalyst residues are still important aspects of research from both economic and environmental points of view. 

Coal liquefaction Fischer-Tropsch synthesis Synthesis of methanol Hydrogenation of oils Alkylation of methanol and benzene Polymerization of olefins Hydrogenation of coal oils, heavy oil fractions, and unsaturated fatty acids Adsorption of S02 in an aqueous slurry of magnesium oxide and calcium carbonate S02 or removal from tail gas Wet oxidation of waste sludge Catalytic desulfurization of petroleum fractions Wastewater treatment... 

Characteristic examples of this form are the hydrogenation reactions, e.g. hydrodesulfurization of petroleum fractions, hydrogenation of oils, and oxidation reactions, e.g. oxidation of pollutants dissolved in liquids. In a few cases such as the Fischer-Tropsch synthesis, the liquid is inert and acts as a heat-transfer medium. 

The temperature may influence the selectivity. For example, in the hydrogenation of oils, a temperature rise causes the hydrogen concentration at the catalyst surface to decrease. In turn, this leads to increased formation of trans-fatty acids [10]. The mechanism can be summarized by stating that a temperature rise causes ... 

Lipids are constituents of plants and animals that are characteristically insoluble in water. Fats and oils are lipids that are triesters formed by reaction of the triol glycerol with long-chain saturated or unsaturated acids called fatty acids. The common acids in fats and oils have an even number of carbons (for example, stearic acid has 18 carbons), and, if unsaturated (for example, oleic acid), they have the Z configuration (Table 15.1 lists the fatty acids, with their common names). Hydrogenation of oils, which have a high percentage of unsaturated acids, converts them to solid fats in a process called hardening. 

In some cases, a slurry reactor with multiple agitation is used. For example, Bern et al. (1976) used the reactor shown in Fig. 15 for the hydrogenation of oils. In this reactor type, horizontal partitions are also introduced at various stages to reduce the extent of backmixing. These authors proposed the following correlation for the gas-liquid mass transfer coefficient, kLaL, in this type of reactor based on pilot-plant data (30 and 500 L capacity) ... 

Iodine Value of Fats and Oils—Cyclohexane Method (IV) (Cd lb-87) measures the unsaturation of fats and oils in terms of centigrams of iodine absorbed per gram of sample. The method is applicable to all normal fats that do not contain conjugated double bonds. It often is used to estimate the degree of hydrogenation of oils. 

In most natural fats the double bonds of unsaturated fatty acids occur in the cis configuration. In milk fat a considerable proportion is in the trans configuration. These trans bonds result from microbial action in the rumen where polyunsaturated fatty acids of the feed are partially hydrogenated. Catalytic hydrogenation of oils in the fat industry... 

Hydrogenation of oils (TG or FAME) at near-critical or super-critical conditions. 

Refining Chemicals Hydrogenation of oils Metals Total... 

High temperature and pressure hydrogenation of oils/fats... 

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