Production of Toluene by Decomposition of 2-Hydroxy-6-methylbenzaldehyde: A DFT Study

摘要

The fast pyrolysis of lignocellulosic biomass produces raw biooil that comprises of several oxygenated organic compounds which are disadvantageous and lower the quality of bio-oil as a fuel. In this numerical study, 2-hydroxy-6-methylbenzaldehyde (HMB) component, one such oxygenated compound which represents aromatic aldehyde category of bio-oil, is considered as model compound for its decomposition within the framework of density functional theory. The bond dissociation analysis of HMB component suggests that the dehydrogenation of methyl group is the least energy demanding amongst all nine possible bond scissions. Further, eight reaction pathways are investigated for the conversion of HMB into toluene as end product along with the analyses of their corresponding potential energy surfaces. Briefly, results indicate that the optimum reaction progress for the production of toluene from HMB requires an activation energy of 12.26 kcal/mol. It is further observed that the production of toluene from HMB includes m-cresol as an intermediate instead of 2-formyltoulene; and, the production of 2-hydroxybenzaldehyde is not favourable. Furthermore, the thermochemistry analyses for the production of toluene using optimum reaction pathway and for the production of 2-hydroxybenzaldehyde using reaction pathway 9 are performed over a wide range of temperature, i. e., 473-873 K at an interval of 100 K. The thermochemistry also suggests higher favourability for the production of toluene compared to the production of 2-hydroxybenzaldehdye by decomposing HMB.