Reaction Mechanism On S-active Groups In Coal And O₂

The main content of this paper is to study the influence of the S-active groups in coal on theprocess of coal spontaneous combustion. On the quantum chemistry theory, its reactionmechanism has been analyzed by the change of energy. It has laid the foundation for the researchof prevention coal spontaneous combustion. All calculations were performed with the Gaussian03program. The reaction mechanism of thiophenol, thiophene and fatty sulfide structure in coaland O2has been studied by using density functional theory (DFT) method. Geometries ofreactants, products, intermediates, and transition states were optimized, at the same time, energyand vibration frequency were evaluated. All computed reaction products and intermediates havereal frequencies, whereas every transition state structure has only one imaginary frequency. Toconfirm that the transition state connects designated reactants, intermediates, and products, theintrinsic reaction coordinate (IRC) were calculated by the same method. Analyzed calculationresults have obtained the following conclusions: the thiophene structure in the three models isthe most likely to be oxidized, it shall be oxidized contacting with oxygen, not need any energyfrom outside; secondly, the fatty sulfide structure takes place oxidation reaction, requires2.95kcal·mol-1energies absorbed from outside; however, the thiophenol structure is the hardest to beoxidized, need absorb41.69kcal·mol-1energies at least from outside.