Advances in the study of hydrogen transfer to model compounds for coal liquefaction

The advances in the study of hydrogen transfer to model compounds for coal liquefaction are reviewed. The results from many model reactions indicate that molecular hydrogen promotes thermolysis, hydrogenation, and hydrocracking of model compounds, whereas hydrogen-donating solvents inhibit the reactions. Unlike metallic catalysts such as Fe, Pd, and Ni, their sulfides catalyze radical hydrogen transfer to model compounds. The reactivities of model compounds toward hydrocracking depend not only on their hydrogen-accepting abilities, but also on their adsorption strength on catalyst surface and the stabilities of the resulting leaving groups.