β-O-4型木质素二聚体高温蒸汽气化机理的理论研究

Theoretical Study on Mechanism of High-temperature Steam-assisted Gasification of β-O-4 Type Lignin Dimer

以β-O-4型木质素为研究对象,将密度泛函理论B3LYP/6-31++G(d,p)运用到Gaussian09中对该木质素二聚体高温蒸汽气化反应进行分子动力学模拟。研究显示,木质素二聚体高温蒸汽气化初反应中,R6和R7的反应焓变较小,分别为237.9kJ/mol和225.5kJ/mol,Cα-Cβ键和β-O-4键较易断开。对于次反应路径,R6-2a和R7-4a的焓变较小,分别为-602.3kJ/mol和-606.3kJ/mol,所以气化中优先发生R6-2a和R7-4a反应。气化反应生成物是苯酚、乙醇、对羟基苯甲醇、对羟基苯甲醛。

The density functional theory B3LYP/6-31＋＋G（d,p） was used to study the reaction mechanism of high-temperature steam-assisted gasification of 13-O-4 type lignin dimer based on quantum chemistry. The results showed that the enthalpy changes of R6 and R7 in the initial reaction of lignin model compound with high temperature steam are 237.9 kJ/mol and 225. 5 kJ/mol, respectively, which meant that C,-Cβ bond and 13-O-4 bond are easy to break. For the secondary rection routes, the calculated R6-2a and R7-4a reaction barriers are -- 602. 3 kJ/mol and --606.3 kJ/mol, respectively,which inferred the priority of R6-2a and R7-4a paths in the gasification process. Pro- ducts via the reaction path calculation included ethanol, phenol, para-hydroxybenzyl alcohol and para-hydroxybenzal- dehyde.