The effects of Fe2O3 and MoS2 on the catalytic activation pathway of hydrogen sources during direct coal liquefaction

Direct coal liquefaction (DCL) can be highly promoted by catalysts due to the acceleration of hydrogen activation. There are two pathways of activation for H2 during the process of DCL. One is that H2 dissolves in the liquid phase and then transfers to coal after splitting (molecular hydrogen), and the other is dissolved H2 is hydrogenated with solvent and then transferred from solvent to coal (transfer hydrogen). In addition, hydrogen in the solvent molecules can be supplied to coal (solvent hydrogen). The effects of two catalysts, Fe2O3 and MoS2, on the activation of molecular hydrogen, transfer hydrogen, and solvent hydrogen during DCL were investigated. Herein, we conducted a series of experiments, including DCL with H2-decalin, DCL with N2-tetralin, tetralin dehydrogenation, naphthalene hydrogenation, and DCL with H2-tetralin. The catalyst and products were characterized by XRD, GC, GC-MS, 1H NMR and TG. Quantum chemistry reveals the catalyst effect on hydrogen activation. The catalytic performance and different hydrogen consumption reveal that the Fe2O3 catalyst primarily activates molecular hydrogen, and MoS2 activates all three kinds of hydrogen. This work not only reveals the catalyst effect on hydrogen activation but also gives light to the design of an appropriate and effective catalyst for DCLs.