重油裂化催化剂活性中心可接近性的研究

STUDY ON ACTIVE SITE ACCESSIBILITY OF HEAVY OIL CRACKING

为了使重油分子能够充分接触催化剂活性中心 ,进而被有效地裂化 ,要求催化剂具有高度可接近的孔结构体系。针对孔分布和孔径等孔结构参数与活性中心可接近性的关系 ,以及如何评价催化剂活性中心可接近性不十分清楚的情况 ,建立了一种较为可行的研究重油裂化催化剂活性中心可接近性的简便方法 ,并用它考察了催化剂基质孔分布对活性中心可接近性的影响。研究结果表明 ,当基质比表面积相近时 ,重油收率和可汽提焦产率随大孔基质的增加而降低。所得结果得到了工业数据的支持。

For heavy oil cracking, the pore structure of catalyst matrix should be accessible for primary cracking of the large hydrocarbon molecules so that the forming smaller molecules can transfer into zeolite channels and further convert to value added products over zeolite sites. However, the relationship between pore parameters, such as pore volume and pore distribution, and catalyst accessibility is not clear. A method for testing the active site accessibility of heavy oil cracking catalyst has been developed through modification of currently widely used MAT equipment. The effects of pore distribution of catalyst matrix on the active site accessibility of several catalysts were tentatively in terms of bottoms conversion and strippable coke yield. The evaluation result showed that the yields of heavy cycle oil and strippable coke increased with the increase of the small pore matrix, and reduced over highly accessible matrix. The test results were well correlated with the commercial results.