In order to understand the effect of traditional solvents on lignin pyrolysis, the decarbonylation and decarboxylation reactions of various phenylic lignin model compounds were theoretically investigated using DFT methods at M06-2×/6–31++G(d,p) level. The calculation results show that activation energy of the decarbonylation and decarboxylation reactions of lignin model compounds can be reduced when HO/CHOH existed. There are two types of reaction for the HO/CHOH during the pyrolysis. For first type, the synergistic reaction of lignin with HO/CHOH as hydrogen transfer carrier. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 285.0–300.0 kJ/mol (HO) and 275.0–290.0 kJ/mol (CHOH) (decarbonylation), 170.0–210.0 kJ/mol and 155.0–200.0 kJ/mol (decarboxylation). For another type, the synergistic reaction of lignin with HO/CHOH as hydrogen source. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 260.0–278.0 kJ/mol and 240.0–260.0 kJ/mol, 303.0–312.0 kJ/mol and 291.0–297.0 kJ/mol. Furthermore, the reaction temperature has the most significant impact on decomposition reaction of lignin in a methanol medium, suggesting that the reaction in the methanol medium is better than that in the water environment.

中文翻译：

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传统溶剂对木质素热分解机理的影响：密度泛函理论研究


为了了解传统溶剂对木质素热解的影响，利用DFT方法在M06-2×/6–31++G(d,p)水平上对各种苯基木质素模型化合物的脱羰和脱羧反应进行了理论研究。计算结果表明，当H2O/CHOH存在时，木质素模型化合物的脱羰和脱羧反应的活化能会降低。 H2O/CHOH 在热解过程中有两种类型的反应。对于第一类，木质素与H2O/CHOH作为氢转移载体的协同反应。此类热解过程中主要元素反应步骤的能垒约为 285.0–300.0 kJ/mol (H2O) 和 275.0–290.0 kJ/mol (CH3OH)（脱羰）、170.0–210.0 kJ/mol 和 155.0–200.0 kJ /mol（脱羧）。另一种是木质素与H2O/CHOH作为氢源的协同反应。此类热解过程中主要元素反应步骤的能垒约为 260.0–278.0 kJ/mol 和 240.0–260.0 kJ/mol、303.0–312.0 kJ/mol 和 291.0–297.0 kJ/mol。此外，反应温度对甲醇介质中木质素的分解反应影响最为显着，表明甲醇介质中的反应优于水环境中的反应。