Quantum chemical simulation of methane production by coal hydrogenation pyrolysis

Abstract

In this work, molecular mechanics, molecular dynamics and semi-empirical quantum chemistry of the Wiser molecular structure model of bituminous coal were studied by molecular simulation. The molecular structure model was optimized and the geometrical configuration of the structural model was analyzed. The bond length and bond cleavage energy of different types of bonds were obtained, and the weak bonds and possible fragments were revealed by a series of simulation. The reaction mechanism of methane production from debris of hydrogenation pyrolysis was studied by transition state theory. The results showed that the energy of the optimal structure of Wiser molecular model of bituminous coal was 704.517 kcal/mol, and the arrangement of aromatic layers was approximately parallel. The initial cleavage of the Wiser model mainly occurs in the coal structure of the relatively high degree of cross-linking and the C-C bond connected to carbonyl carbon. The three-dimensional structure of Wiser model was broken and then generated a large number of debris, the groups of methyl were removed from debris molecules under hydrogen atmosphere, and then methyl radicals and hydrogen radicals combined to form methane.