Understanding the relationship between composition and hydrodesulfurization properties for cobalt phosphide catalysts

Silica-supported cobalt phosphide (Co(x)P(y)/SiO(2)) catalysts, prepared from precursors having P/Co molar ratios in the range 0.50-2.0, were characterized and evaluated for thiophene hydrodesulfurization (HIDS). The HDS activities of the CO(x)P(y)/SiO(2) catalysts varied nearly four-fold depending on the composition of the Co phosphide phase, with the most active CO(x)P(y)/SiO(2) catalyst corresponding to the precursor composition having just enough P to ensure formation of phase-pure CoP on the silica support. The maximum in HIDS activity observed for this Co phosphide composition can be correlated with a balance between site density (as measured by 02 chemisorption) and resistance to S incorporation (as measured by S analysis of catalysts subjected to an H(2)S/H(2) treatment). (C) 2008 Published by Elsevier B.V.