BASIC STUDIES OF DEACTIVATION OF HYDROTREATING CATALYSTS WITH ANTHRACENE

A sulfided commercial Ni-Mo-P/alumina catalyst was coked in an autoclave reactor at 375-degrees-C with solutions of anthracene in mineral oil to give catalysts containing 2-12% C. After extraction and resulfiding, physical properties and catalytic activities using a mixture of model compounds were measured. It was found that the coke was evenly distributed throughout the catalyst particles. All physical properties decreased with increasing coke content. Only a small fraction of pores was blocked by coke. Diffusivity measurements indicated internal pore mouths were constricted by coke. Catalytic activities for hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodenitrogenation (HDN) all decreased with increasing coke content, but not to the same extent, the order of deactivation being: HDS > HYD > HDN. The results are interpreted in terms of a pore-wedge model of coke deposits.