基于分子动力学的生物沥青相容性研究

Research on the Compatibility of Bio-Asphalt Based on Molecular Dynamics

为了评价木屑热裂解生物油与沥青的相容性,基于分子动力学方法构建了基质沥青、生物油及生物沥青模型,采用分子极性、溶解度参数和结合能指标定量分析了生物油与沥青及其各组分的相容性;同时,借助离析试验对模拟结果进行了验证。结果表明:生物油的溶解度参数与沥青质组分较为接近,两者均具有较强的极性、更容易产生吸附;随着温度升高,生物油与沥青的溶解度参数差逐渐变大,结合能逐渐下降,当生物沥青混合体系温度超过433 K时,两者的溶解度参数差和结合能参数会出现明显的劣化;温度达到453 K时生物沥青的储存稳定性下降较为明显;为了保证生物油和沥青的相容性,避免高温储存过程中发生严重离析,建议生物沥青的储存温度不宜高于433 K。

Molecular models of base asphalt,bio-oil,and bio-asphalt were constructed based on molecular dynamics in order to study the compatibility of wood chip based bio-oil and asphalt,and the compatibility of bio-oil with asphalt and its components was quantitatively analyzed by molecular polarity,solubility parameters,and binding energy.The simulation results were validated with the help of the segregation test.The results show that the solubility parameters of bio-oil are closer to those of asphaltene fraction,both of them having stronger polarities and more susceptible to adsorption.As the temperature increases,the difference in solubility parameters between bio-oil and asphalt gradually becomes larger and the binding energy gradually decreases.The difference of parameters in solubility and the binding energy significantly deteriorates when the system temperature exceeds 433 K,and the storage stability of bio-asphalt decreases obviously when the temperature reaches 453 K.To ensure the compatibility between bio-oil and asphalt and avoid serious segregation during high-temperature storage,it is recommended that the storage temperature of bio-asphalt should not exceed 433 K.