Thermal decomposition pathways of 4-ethylguaiacol under fast pyrolysis and gasification conditions

摘要

Thermal decomposition pathways for the vapor-phase, homogeneous pyrolysis of 4-ethylguaiacol were examined. Experiments were conducted using a laminar-flow reactor operated at atmospheric pressure, temperatures in the range 300-900 degrees C, and a residence time of one second, Analysis of the products by gas chromatography shows that they can be categorized as light gases, oxygen-containing compounds, and aromatic hydrocarbons. The major products observed were: methane, ethane, ethylene, acetylene, and carbon monoxide for the light gases; 4-ethylcatechol, 5-ethyl-2-hydroxybenzaldehdye, and 4-ethylphenol for the oxygen-containing products; benzene, indene, and naphthalene for the aromatic hydrocarbons. The product distribution was strongly influenced by temperature, with the oxygen-containing compounds dominating at temperatures below 700 degrees C, while light gases and aromatic hydrocarbons dominated above 700 degrees C. By consideration of the product distributions and analogous reactions based on established thermal decomposition mechanisms of structurally-similar compounds, reaction pathways leading to the generation of major products are proposed and discussed. Computational chemistry calculations at the B3LYP/6-311G + (2d,p) level of theory were performed to complement the proposed pathways. The results presented in this study would be of relevance to lignin fast pyrolysis and gasification processes. (C) 2016 Elsevier B.V. All rights reserved.