Study On The Hydrodesulfurization Catalyst In Coking Crude Benzene

Shanxi province is the country’s largest coking industrial and crude benzene productionbase. Crude benzene composition is complex, mainly through hydrofiging for benzene,toluene and xylene （called the BTX） and other chemical raw materials. So it’s significant toresearch the hydrogenation catalyst of the coking crude benzene.This paper focuses on the study of supported CoMo catalysts in benzene hydrogenationdesulfurization （HDS） reaction activity. The thiophene conversion as the main evaluationindex and as much as possible to improve BTX recovery. The experimental results showedthat when nCo/n（Co+Mo） ratio was0.3, the mass fractions of CoO and MoO₃relative to thealumina were2%and8%, the hydrodesulfurization activity of the catalyst prepared byCo-Mo co-impregnation method was the highest, meanwhile BTX retention rate maintaineda high level. HDS reaction of the real-feedstock was studied by using a down-flow tubularreactor with the first-stage temperature of220℃, second-stage temperature of300℃, LHSVof2h^-1, H₂pressure of3MPa and hydrogen-oil volume ratio of600, the catalytic activityof HDS has the best performance.The chelating agents of ethylenediamine tetraacetic acid （EDTA）, citric acid （CA）,oxalic acid （OA） and their amount on the catalytic activity of HDS were investigated, theresults show that: with the rate of n（Co）: n（EDTA）=1:0.5, n（Co）: n（CA）=1:1andn（Co）:n（OA）=1:1.5, the catalytic activity of HDS reached the highest. Under the optimumconditions the thiophene conversion reached99.9%and the Co-Mo-CA/Al₂O₃catalystexhibited good stability in a100-hour life test.