Hydrogen shuttling pathways in thermal hydroliquefaction: Solvent-induced scission of coal model compound structures

Abstract

It has been demonstrated that donor solvents play a key role in the scission of thermal stable bonds in coal model compounds and therefore it has been speculated that they will improve liquefaction efficiencies. The authors have been studying the transfer of hydrogen from dihydroarene donor solvents to arene model compounds to quantify the barriers of competing hydrogen transfer mechanisms. Hydrogen can be transferred between arene rings by a variety of pathways. The specific hydrogen transfer pathway or pathways can be predicted given an understanding of the thermochemistry of the reactants intermediates and products. The individual pathways that contribute to strong bond scission have been shown to be dependent on the dihydroarene donor and the arene acceptor. In this paper they quantify the hydrogen pathways between the solvent components anthracene and phenanthrene. In addition, they describe reaction conditions requiring consideration of an additional hydrogen transfer pathway: a multi-step nonipso hydrogen transfer to coal model compounds to evaluate the hydrogen transfer steps to cleave strong diarylmethane bonds in coal structures.