Devolatilization, a molecular modeling approach

Simulated devolatilization of in-house generated molecular models, which are representative of both the chemical and physical structures of bituminous coals, provides a unique insight into bond breaking and bond reforming mechanisms. A series of molecular models for rapidly heated bituminous vitrinites chars is presented. It was necessary to include bond formation in addition to bond breaking reactions to simulate the devolatilization process. Strong bond cleavage, sometimes prior to weak bond cleavage, was important for structural transitions. Structural units attached to the vitrinite/vitrinite-char matrix with two or fewer bonds contributed the bulk of the mass loss. However, bond-forming reactions also incorporate such structures into the char matrix, thereby reducing their probability of release. Internal hydrogen redistribution is responsible for the extent of molecular orientation in these bituminous vitrinite chars.