加氢反应条件下重油分子在多尺度复合孔道催化剂中的反应扩散行为

重质油催化加氢反应受内扩散控制，需要大的孔道以提升扩散系数，但这又会降低催化剂的比表面积，最终降低本征化学反应速度。为了平衡扩散速度和本征反应速度，使总反应速度最大，通常将催化剂设计成多尺度复合孔道。如何测量和计算复合孔道催化剂内扩散系数是重要研究课题。但由于实验材料所限，人们尚不能准确研究催化剂孔内本征扩散系数与孔径的相关性，更无法研究复合孔道催化剂内的扩散系数。针对这个问题，本项目提出利用单分散SiO2微球有序组装得到的孔径均一、三维有序孔材料作为载体，先嫁接Al2O3再担载加氢活性组份，合成孔结构三维有序的加氢催化剂。利用这种催化剂，研究测定重油组份在加氢催化剂孔内本征扩散系数和体相扩散系数。通过纳米颗粒的二次组装，合成孔结构已知的复合孔道加氢催化剂，研究多级复合孔道催化剂内的重油加氢反应扩散行为。本项目提出的研究思想，也适合于研究其它反应体系的催化剂内反应扩散行为，具有普遍意义。

Heavy oil hydroprocessing is controlled by the intra particle diffusion. Large pores are prefered for the hydroprocessing catalyst. However, large pores will result in lower specific surface area and hence lower intrinsic chemical reaction rate. In order to balance the diffusion rate and intrinsic chemical reaction rate and achieve maximum overal reaction rate, hierarchically porous catalysts are generally used for industry applications. How to determine and calculate the intra particle diffusion coefficient in hierarchically porous catalysts is one of the important issues for the heavy oil processing. Because of the absence of well-difined and uniform porous catalyst, we can not obtain the intrinsic diffusion coefficient and the effective diffusion coefficient of hierarchically porous catalysts. In order to solve these problems, this project will synthesize well-defined and three dimensional uniform pore-size catalysts and use the catalysts to measure the intra-particle intrinsic diffusion coefficient of heavy oil components under the reactive conditions. The well-difined hierarchically porous catalysts will be fabricated through twice self-assembly of nano-particles and used to investigate the the effective diffusion coefficient of hierarchically porous catalysts. The idea proposed by this project is useful not only for the intra particle diffusion study of heavy oil hydroprocessing, but also for the study of other reaction systems, in which the processes are controlled by intra particle diffusion.