Investigation of mechanism of reactions involving oxygen-containing compounds in coal hydrogenation. Final report

Abstract

The objective of this project was two-fold, namely, to develop an understanding of reactions involving oxygen during hydrogenative liquefaction and to establish a kinetic model to describe coal liquefaction. Emphasis was directed toward the liquefaction of Belle Ayr subbituminous coal with subsequent test runs made with Burning Star bituminous coal. The liquefaction experiments were made in a CFSTR bench-scale unit operated at temperatures between 400 and 470/sup 0/C, space timees between 5 and 60 minutes and a fixed total pressure of 2000 psig. It was shown that between 70% and 85% of the coal organic oxygen is removed as carbon oxides and water. Carboxylic, carbonylic, and etheric functionalities of coal are essentially removed during the liquefaction reaction. The most abundant oxygen-containing group in the reaction product is hydroxylic, a portion of which is necessarily formed by a reduction of other groups. The results of liquefying Belle Ayr coal were correlated by a kinetic model. It is shown that this reaction mechanism (with all reaction rates assumed to be pseudo first order with respect to reacting species) correlates data reasonably well at the temperature levels of 400/sup 0/C, 425/sup 0/C, and 450/sup 0/C for all space times, and at 460/sup 0/Cmore » and 470/sup 0/C for small space times. The donor capacity of the solvent strongly affects the rates of the various reactions. This model does not correlate the data for the liquefaction of Burning Star coal in that negative oil yields are observed at short space times. These negative yields are due to solvent entrapment and/or reaction of the solvent with heavy coal liquefactions products. « less

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