β-1型木质素二聚体高温蒸汽气化机理的理论研究

以β-1型木质素二聚体为研究对象,采用以密度泛函理论B3LYP/6-31G(d,p)为基础的Gaussian工具包对该木质素二聚体的高温纯蒸汽气化反应过程进行了分子动力学模拟研究。结果表明,在木质素二聚体高温蒸汽气化的初反应中,R4和R5的反应焓变较小分别为243.9和323.2 kJ/mol,Cα-Cβ键和Cβ-C1键较易断裂。通过计算次反应路径的势垒,发现R4-1和R5-1反应的势垒较小分别为4.4和24.0 kJ/mol,因此,在该气化过程中会优先选择R4-1和R5-1路径。该反应路径最后得到的产物有甲醇、乙醇、苯酚、对羟基甲苯和对羟基苯甲醛,与实验产物吻合。

Theoretical study on gasification of β-1 type lignin dimer with high temperature steam

The density functional theory B3LYP/6-31G(d,p) was used to study the reaction mechanism of β-1 type lignin dimer gasification with high temperature steam based on quantum chemistry. The results show that the enthalpies of R4 and R5 in the beginning of reaction of lignin model compound with high temperature steam, are 243.9 kJ/mol and 323.2 kJ/mol, respectively. These values mean that C_α-C_β bond and C_β-C₁ bond are easy to break. By the calculation, R4-1 and R5-1 reaction barriers are 4.4 kJ/mol and 24.0 kJ/mol, respectively. Thus it is of priority to choose the R4-1 and R5-1 paths in the gasification process. Products via the reaction path calculation include ethanol, methanol, phenol hydroxy toluene and p-hydroxybenzaldehyde, which agree with the experimental results.