紫丁香基木质素是一种重要的木质素，天然木质素也大多通过β-O-4键连接成网状结构，β-O-4型紫丁香基木质素二聚体模化物在前人研究的模化物基础上增加了多个甲氧基基团，更接近实际的紫丁香基木质素结构。在软件Materials Studio 2019的Dmol³模块中，基于密度泛函理论利用B3LYP杂化泛函，对β-O-4型紫丁香基木质素二聚体模化物在875 K、101 kPa条件下的热解反应路径进行模拟，计算每步反应的反应物与生成物的焓值，并通过Vibration Analysis模块进行频率分析确认只有实频，没有虚频；计算每步反应的焓变并对反应路径总焓变进行比较，总焓变越小表明该路径在热力学上越容易发生，进而得到其较具优势的反应路径，最终得到对应路径的热解产物。结果表明，β-O-4型紫丁香基木质素二聚体模化物在875 K、101 kPa下的初步热解较有可能发生C _α —C _β 键的断裂与β-O-4键的断裂，其中最可能发生β-O-4键的断裂；较具优势的反应路径包括总焓变为-59.65 kJ/mol的R4、总焓变为-219.44 kJ/mol的R10、总焓变为-14.93 kJ/mol的R12、总焓变为-389.29 kJ/mol的R21、总焓变为-466.24 kJ/mol的R23与总焓变为-276.72 kJ/mol的R24，其中最具优势的路径为R21、R23与R24；热解的主要产物是邻苯三酚、3，4，5-三羟基苯甲醇、3，4，5-三羟基苯甲醛及乙醇，其中邻苯三酚、3，4，5-三羟基苯甲醇与乙醇为R21、R23与R24的热解产物。本研究得到的模拟结果可以为生成生物质焦的进一步模拟计算奠定基础。

Lilac-based lignin is an important lignin. Most of the natural lignins are connected through β-O- 4 bonds to form a reticular structure. β-O- 4-type lilac-based lignin dimeric modulators are closer to the actual lilac-based lignin structure, as multiple methoxy groups were added to it on the basis of the modulators studied by the previous researchers. In the Dmol³ module of the software Materials Studio 2019, the pyrolysis reaction paths of β-O- 4 lilac-based lignin dimer modulators were simulated based on the density flooding theory using the B3LYP hybridization flooding at 875 K and 101 kPa. The enthalpy values of the reactants and products were calculated for each step of the reaction, and the frequency analysis was carried out by the Vibration Analysis module to confirm that there were only real frequencies and no imaginary frequencies; the enthalpy change of each step of the reaction was calculated and the total enthalpy change of the reaction paths was compared. The smaller the total enthalpy change was, the easier the paths were to take place thermodynamically, and then the more advantageous reaction paths were obtained to get the pyrolysis products of the corresponding paths finally. The results show that the initial pyrolysis of β-O- 4 lilac-based lignin dimer modulators at 875 K and 101 kPa is more likely to involve the breakage of the C _α —C _β bond and the β-O- 4 bond, among which the breakage of the β-O- 4 bond is the most likely to occur. The more favorable reaction paths include R4 with a total enthalpy change of -59.65 kJ/mol, R10 with a total enthalpy change of -219.44 kJ/mol, R12 with a total enthalpy change of -14.93 kJ/mol, R21 with a total enthalpy change of -389.29 kJ/mol, R23 with a total enthalpy change of -466.24 kJ/mol, and R24 with a total enthalpy change of -276.72 kJ/mol, with the most favorable paths being R21, R23 and R24.The main products of pyrolysis are o-benzenetriol, 3,4,5-trihydroxybenzyl alcohol, 3,4,5-trihydroxybenzaldehyde and ethanol, among which o-benzenetriol, 3,4,5-trihydroxybenzyl alcohol and ethanol are the pyrolysis products of R21, R23 and R24. The simulation results obtained in this study can lay the foundation for further simulation calculations for generating biomass coke.