Hydrogenation of coals

When heated with small amounts of iodine, rosins, taU. oil, and other wood products are converted to more stable forms (135,136). Iodine has been used with some tin salts as a catalyst in the hydrogenation of coal (qv) and its distillation products (137,138), and has been recommended as a catalyst for the production of drying oils (qv) from unsaturated animal fats (139,140). 

Stannous oxalate is used as an esterification and transesterification catalyst for the preparation of alkyds, esters, and polyesters (172,173). In esterification reactions, it limits the undeskable side reactions responsible for the degradation of esters at preparation temperatures. The U.S. Bureau of Mines conducted research on the use of stannous oxalate as a catalyst in the hydrogenation of coal (174) (see Coal). 

Hydrogenation of Coal in the Batch Autoclave, U.S. Bureau of Mines Bulletin 622, U.S. Bureau of Mines, Washington, D.C., 1965. 

Goal Processing to Synthetic Fuels and Other Products. The primary approaches to coal processing or coal conversion are thermal decomposition, including pyrolysis or carbonization (5,6), gasification (6), and Hquefaction by hydrogenation (6). The hydrogenation of coal is not currently practiced commercially. 

E. E. Donath, "Hydrogenation of Coal and Tar," in H. H. Lowry, ed.. Chemistry of Coal Utilisation, Supplementay Uolume, okm. Wiley Sons, Inc., New York, 1963. 

Tabic 6. Estimated degree of hydrogenation of coals as a function of hydrogenation temperature... 

The effect of the mineral matter content and of the inorganic sulphur content on the hydrogenation of coal were also studied. 

It has been demonstrated that certain coal minerals, particularly iron compounds, catalyze the hydrogenation of coal-derived solvents (15). Mukherjee et al (16) hydrogenated float/ sink fractions of an Indian coal and found that the conversion increased with the amount of mineral matter present in the fraction. 

Three of the most important parameters that affect the hydrogenation of coal and the products obtained are the catalyst, the temperature and the residence time. The effects of these parameters on the chemical nature of the products are still not fully understood. 

The first step — hydrogenation of coal — was the same for fuels and rubber. Powdered coal suspended in oil was pumped under great pressure with hydrogen over a catalyst and was converted into a synthetic crude oil. From this crude oil came Leuna gasoline, diesel fuel, iso-octane for aviation gasoline, ethylene oxide, and many other synthetic products. Coal, treated with scalding steam, was also processed into methanol. 

Hydrogenation of coal is a highly exothermic reaction corresponding to a heat evolution of about 15 kilojoules per cubic metre of hydrogen reacted. Means must be provided to remove this heat from the reaction zone so that the reaction temperature can be maintained in the optimum range. This is usually accomplished by injecting coal liquid as quench into various sections of the reac tor. 

Direct Liquefaction Kinetics Hydrogenation of coal in a slurry is a complex process, the mechanism of which is not fully understood. It is generaly believed that coal first decomposes in the solvent to form free raclicals which are then stabilized by extraction of hydrogen from hydroaromatic solvent molecules, such as tetralin. If the solvent does not possess sufficient hydrogen transfer capability, the free radicals can recombine (undergo retrograde reactions) to form heavy, nonliquid molecules. A greatly simplified model of the liquefaction process is shown below. 

Much of the research pursued by the authors of this paper and by their associates has involved studies of the catalytic hydrogenation of coals in the absence of solvent. The technique has been used to elucidate the mechanisms of catalytic coal liquefaction and to provide simultaneously some insight into the structure of coals. Peter Given was directly instrumental in providing the incentive for this research which has extended since 1983. Previous findings were disseminated through several publications (4-8. In this paper, some of the earlier data have been collated with more recent results (9) to provide an account of the relevance of these studies to the two-component concept. 

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... 

The second, catalytic liquefaction process is similar to the first except that there is a catalyst in direct contact with the coal. ZnCl2 and other Friedel-Crafts catalysts, including AICI3, as well as BFj-phenol and other complexes catalyze the depolymerization-hydrogenation of coals, but usually forceful conditions (375 t25°C, 100-200 atm) are needed. Superacidic HF-BF3-induced liquefaction of coals8 involves depolymerization-ionic hydrogenation at relatively modest 150-170°C. 

An extreme case of the effectiveness of ionic hydrogenation is the HF-BF3 superacid-promoted hydrogenation of coals at 170°C with 36-atm hydrogen giving efficiently liquid products under these relatively mild conditions.245,246... 

Major, Minor, and Trace Elements in the Liquid Product and Solid Residue from Catalytic Hydrogenation of Coals... 

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