表面可控接枝聚合物降凝剂分子的复合PSQ微球对蜡油体系析蜡特性与流变行为的调控机理研究

At present, the polymer/inorganic composite particle pour point depressants (PPDs) have become a research hotspot in the waxy crude oil pipeline transportation domain. However, the deficiencies of the developed composite particle PPDs urge the preparation of the composite particle PPDs with controllable morphology and surface grafting state, so as to deepen the theoretical development of the composite particle PPDs. Based on the unique advantages of the surface-initiated controllable radical polymerization (SI-CRP) grafting technique and the excellent morphological and structural characteristics of polysilsesquioxane (PSQ) mini-spheres, in this project, surface controllable polymeric PPDs molecules-grated composite PSQ mini-spheres will be first prepared through the SI-CRP method; the structure and performance of the prepared composite mini-spheres will also be characterized. Then, the controlling laws of the composite mini-spheres on the wax precipitating exothermic characteristics, wax crystal’s morphology and structure of waxy oil system are studied and the relevant controlling mechanisms are discovered. The rheological improving effect of the composite mini-spheres on waxy oil system is investigated; the effects of composite mini-sphere size, surface grafting morphology, waxy oil composition and pipeline transporting conditions on the improving effects are discovered. Finally, the rheological controlling mechanisms of the composite mini-spheres on waxy oil system are discovered based on the inherent relationships between the wax precipitating characteristics and the rheological behaviors; the composite PSQ mini-sphere PPDs with excellent performance are developed. The studies mentioned above will further promote the theoretical development of the composite particle PPDs, which plays a significant role in transporting waxy crude oils more economically and safely.

当前聚合物/无机复合颗粒降凝剂正成为含蜡原油管输领域的研究热点，而已开发复合颗粒降凝剂存在的不足迫切要求研制形貌与表面接枝状态可控的复合颗粒降凝剂，以深化该类降凝剂的理论发展。基于表面引发可控自由基聚合（SI-CRP）接枝技术的独特优势和聚有机硅倍半氧烷（PSQ）微球良好的形貌、结构特性，本项目将首先通过SI-CRP制备表面可控接枝聚合物降凝剂分子的复合PSQ微球并对其结构与性能进行表征；然后考察复合微球对蜡油体系析蜡放热特性、蜡晶微观形貌与结构的调控规律并揭示相关调控机理；考察复合微球对蜡油体系的流变改善效果，揭示复合微球尺寸、表面接枝状态、蜡油组成、管输工艺条件等因素对作用效果的影响；最后在建立蜡油析蜡特性与流变行为内在联系的基础上，揭示复合微球对蜡油体系的流变调控机理，开发高效复合PSQ微球降凝剂。上述研究将进一步推动复合颗粒降凝剂的理论发展，这对含蜡原油的经济安全输送具有重要意义。

当前聚合物/无机纳米复合降凝剂正成为含蜡原油管输领域的研究热点，但人们对聚合物型降凝剂本身以及复合降凝剂作用机理的认知依然有限，这极大限制了新型高效降凝剂的开发。本项目成功合成了多种不同分子结构的聚合物降凝剂，考察了降凝剂分子与缔合沥青质胶粒对蜡油体系流变性的共同影响，揭示了两者协同改善蜡油流变性的规律及机理；通过化学接枝方法成功制备了表面接枝聚合物降凝剂分子的PSQ纳米复合降凝剂，考察了复合剂降凝剂的结构与作用性能；通过物理共混方法成功制备了多种PSQ基微纳米复合剂降凝剂，深入揭示了复合剂降凝剂的降凝防蜡规律及机理；考察了热处理温度、沥青质极性、多种聚合物降凝剂（POA、EVA等）对蜡油体系蜡沉积特性的影响规律及机理。研究发现：(1) 单独的沥青质或聚合物降凝剂对蜡油体系流变性改善效果有限，而同时添加沥青质和降凝剂能够大幅改善蜡油流变性，体现出显著的协同作用；降凝剂分子能够吸附于沥青质胶粒表面形成复合颗粒降凝剂，该复合颗粒通过蜡结晶模板作用促进大尺寸、结构紧凑蜡晶的形成，进而深度改善蜡油流变性；含强极性基团、芳香基团的聚合物降凝剂更易吸附于沥青质表面，协同作用更显著。 (2) 接枝型复合降凝剂的表面接枝率较低且难以有效提高，与物理共混型复合降凝剂相比较，其作用效果并不理想。 (3) 通过物理共混制备了PMSQ/EVA、PAMSQ/EVA等多种复合降凝剂，发现EVA聚合物分子能够吸附于PSQ微球表面形成复合微球，该复合微球通过蜡结晶模板作用促进大尺寸、结构紧凑蜡晶的形成，进一步改善蜡油流变性；粒径约2微米、含氨基的PAMSQ微球与EVA分子的作用更强，表面吸附量更高，因而PAMSQ/EVA复合降凝剂的作用效果最佳；PAMSQ/EVA复合降凝剂也具有良好的防蜡效果，显著降低蜡沉积速率。(4) 提高热处理温度促进了沥青质在含蜡原油中的胶溶分散，促进了沥青质-石蜡分子相互作用，因而能够进一步改善含蜡原油低温流动性、抑制蜡沉积；随着沥青质极性的减弱，沥青质的H/C比增大，油相分散性提高，与石蜡分子的作用增强，从而促进降凝防蜡；POA、EVA降凝剂均能够抑制蜡沉积，但所形成的蜡沉积结构显著不同，POA所形成的蜡沉积为二元分层结构，底层蜡沉积薄而致密，表层蜡沉积厚而疏松，EVA所形成的蜡沉积从底层到表层逐渐变致密，没有明显分界。