减压渣油微观相结构特性的分子模拟

选用4种模型化合物代表减压渣油四组分(SARA)，采用分子动力学模拟了减压渣油微观相结构，发现不同结构分子间相互作用的差异是减压渣油微观非均匀分布的本质原因，并通过电子分布特性分析了不同结构分子间相互作用差异的本质原因。沥青质分子间强相互作用使得沥青质分子自缔合形成聚集体；而多个胶质分子与沥青质分子的强相互作用封闭了沥青质分子自身进一步发生相互作用的活性位；同时，与胶质分子、饱和烃分子具有强相互作用的芳香烃分子将沥青质 胶质分子形成的聚集体分散在由芳香烃 饱和烃分子构成的连续相内，其中芳香烃分子更靠近胶质分子。因此，增加沥青质、饱和烃分子的含量会促进沥青质聚集，降低减压渣油稳定性；增加胶质、芳香烃分子的含量会阻碍沥青质聚集，提高减压渣油稳定性。

Molecular Simulation on the Microphase Structure of Vacuum Residue

Four model compounds were chose to represent the saturate, aromatic, resin, and asphaltene (SARA) fractions of VR, and the microphase structure of their mixtures was investigated by molecular dynamics simulation. The results show that the interaction between different molecules is the main factor to control their stability. Subsequently, the intermolecular interactions were analyzed by quantum chemical calculations. It is found that the self-association of asphaltene is the reason of the strong asphaltene-asphaltene intermolecular interactions. Active sites of asphaltene which further interact with themselves are blocked by the resin asphaltene interactions. Aromatics molecules with long side chains and aromatic rings interact with saturates and resin simultaneously and disperse the small aggregates in a continuous phase composed of aromatics and saturates, where aromatics are closer to resin molecules. Therefore, increasing the content of asphaltenes and saturates promotes asphaltenes aggregation and reduces microphase stability while increasing the content of resins and aromatics shows a contrary tendency.