Dehydrogenation/Hydrogenation Reactions in Hydroaromatic Systems

摘要

The basic chemistry of the donor solvent dehydrogenation/hydrogenation process is an important component of liquefaction to understand. Kinetic and mechanistic work on the hydroaromatic donors: tetralin (T), 1,2-dihydronaphthalene (DN) and 9,10-dihydroanthracene (DA) is yielding insight into this chemistry. The chemistry of the dehydrogenation/hydrogenation reactions in the neat donor solvent systems has been found to be heterogeneously controlled. The composition of the product mixtures are sensitive to the initial density of the hydroaromatic reactant. As the reactant density increases, the tetralin product mix changes from 1,2-dihydronaphthalene/naphthalene (N) to methylindane (M)/naphthalene. For the 9,10-dihydroanthracene system anthracene (A) is a major product but the yield of 1,2,3,4-tetrahydroanthracene (TA) increases as the initial reactant density is increased. Reaction mechanisms for these hydroaromatic systems are proposed which describe the observed dehydrogenation/hydrogenation processes in terms of reversible heterogeneous site reactions. Based on kinetic studies, a general reaction mechanism has been developed which describe the observed reactant/product sequences. Results of the kinetic and mechanistic investigations of these systems are presented. Conclusions are as follows: the hydrogenation/dehydrogenation reactions of the hydroaromatic systems studied can be modeled using the proposed heterogeneous reaction mechanism; the dihydro-reactants can react along more than one pathway; and the extent of reaction for these different pathways is a function of the hydrogen content of the heterogeneous surface. (ERA citation 06:029768)