Quantum chemistry simulation and kinetic analysis of organic nitrogen transfer during oil shale pyrolysis

Abstract

The nitrogen in oil shale would cause the generation of heteroatomic compounds during the pyrolysis, causing fuel instability, viscosity increase, glue formation and discoloration. To explore the formation mechanism of the nitrogenous substances, the relevant reaction paths and the corresponding kinetic analysis during the pyrolysis were constructed and conducted in this paper. Through quantum chemical transition state theory combing with density functional theory, the energy of reactants, transition states and intermediates involving in the reaction was obtained. Moreover, the energy distribution diagrams were also constructed to further clarify the formation mechanism of typical organic nitrogen product. In the exist of some functional groups like hydroxy, the N-containing rings such as pyrrole and pyridine are more easily to be opened, generating NH₃ and NO. Five kinds of pathways constructed by this paper were chosen as the representational paths for revealing the micro theoretical mechanism of organic nitrogen conversion in oil shale. The results could provide reliable theoretical basis for investigating the conversion mechanism of nitrogen in oil shale pyrolysis and further reducing the NO_x emission in the future.