Reaction Mechanisms of Anisole Pyrolysis at Different Temperatures: Experimental and Theoretical Studies
Reaction Mechanisms of Anisole Pyrolysis at Different Temperatures: Experimental and Theoretical Studies
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DOI：
10.1021/acs.energyfuels.1c00858
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发表时间：
2021-06
期刊：
影响因子：
5.3
通讯作者：
Tingyu Zhang;Chiranjivi Bhattarai;Y. Son;V. Samburova;A. Khlystov;S. Varganov
中科院分区：
文献类型：
--
作者：
Tingyu Zhang;Chiranjivi Bhattarai;Y. Son;V. Samburova;A. Khlystov;S. Varganov
焦油化合物的热解在设计将生物质转化为全球重要商品的最佳热化学过程中起着重要作用。因此，了解相关的反应机制，并能够预测这些化合物在不同温度下的分解产物是至关重要的。本研究在N2gas层流反应器系统中，研究了作为生物质焦油主要成分木质素重要模型化合物的苯甲醚在300-650℃、停留时间1 s条件下的热解过程。采用气相色谱仪、质谱联用仪和火焰电离检测器对分解产物进行分析。为了深入了解反应机理，利用密度泛函理论和高耦合簇方法对单分子和双分子的分解途径进行了详细的研究。发现苯甲醚在低至400℃的温度下分解，这是报道的苯甲醚分解的最低温度。苯和甲苯在低温（400-450℃）下的形成是由苯环甲醚甲氧基部分的ch3和H自由基的低能势垒ipso加成所解释的。在500-550℃下，多种反应机制可生成苯并呋喃、甲基环戊二烯、苯甲醛、环戊二烯、乙苯、苯乙烯和对二甲苯。最后，在600-650℃下，检测吲哚、苯酚和甲酚。所得结果有望为苯甲醚和其他类似化合物分解的预测动力学模型的发展作出贡献。
Pyrolysis of tar compounds plays an important role in designing optimal thermochemical processes for the conversion of biomass into globally important commodities. Therefore, it is crucial to understand the relevant reaction mechanisms and be able to predict the decomposition products of these compounds at different temperatures. In this study, the pyrolysis of anisole, which serves as an important model compound for lignin, a major component of biomass tar, was studied in a laminar-flow reactor system of N2gas at temperatures of 300–650 °C and a residence time of 1 s. The decomposition products were analyzed using a gas chromatograph with mass spectrometric and flame ionization detectors. To gain insights into the reaction mechanisms, detailed studies of the unimolecular and bimolecular decomposition pathways were carried out using the density functional theory and high-level coupled cluster methods. Anisole was found to decompose at temperature as low as 400 °C, which is the lowest reported temperature for anisole decomposition. Formation of benzene and toluene at low temperatures (400–450 °C) is explained by the low-energy barrier ipso-addition of CH3and H radicals at the methoxy moiety of anisole. At 500–550 °C, multiple reaction mechanisms lead to the formation of benzofuran, methylcyclopentadiene, benzaldehyde, cyclopentadiene, ethylbenzene, styrene, ando-xylene. Finally, at 600–650 °C, indene, phenol, and cresol were detected. The obtained results are expected to contribute to the development of predictive kinetic models for the decomposition of anisole and other similar compounds.