Hydrodesulfurization of dibenzothiophene and its hydrogenated intermediates over bulk CoP and Co2P catalysts with stoichiometric P/Co ratios

CoP and Co 2 P were prepared by temperature-programmed reduction of the mixtures of Co(OH) 2 and H 3 PO 3 with stoichiometric P/Co ratios, but their surfaces were still enriched in phosphorus. Based on the product distributions of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), 1,2,3,4-tetrahydro-dibenzothiophene (TH-DBT), and 1,2,3,4,4a,9b-hexahydro-dibenzothiophene (HH-DBT), a reaction network of DBT HDS was proposed and the mechanisms of the cleavage of different C S bonds in DBT and its hydrogenated intermediates were discussed. CoP was much more active and more nitrogen-tolerant than Co 2 P, which make it a promising HDS catalyst. The HDS reactions over CoP and Co 2 P followed a pseudo-first-order kinetics and a pseudo-zero-order kinetics, respectively. Piperidine strongly inhibited the hydrogenation/dehydrogenation reactions and the direct desulfurization of DBT, but its inhibition on the desulfurization of TH-DBT and HH-DBT were less pronounced. The active surfaces of CoP and Co 2 P in HDS reactions can be cobalt phosphosulfide phases.