Silica-supported Ni2P: effect of preparation conditions on structure and catalytic performance in thiophene hydrodesulfurization (HDS)

Silica-supported Ni2P catalysts were synthesized from precursors, which were either prepared by sequential impregnation of phosphorus (i.e. phosphate, phosphite and hypophosphite) on calcined NiO/SiO2, or by co-impregnation of nickel and phosphorus and subsequent reduction with hydrogen. Ni2P formation mechanisms, as investigated by means of TPR-MS, XRD and XPS, varied as a function of preparation method. Catalytic performance of the resulting Ni2P materials was evaluated in thiophene hydrodesulfurization; particle size was characterized by TEM. Catalysts prepared by sequential impregnation and subsequent calcination were less active than samples prepared by co-impregnation without calcination because of significantly lower Ni2P dispersion due to calcination. For catalysts prepared by co-impregnation the activity increased with increasing reducibility of the P precursor, i.e. in the order NH4H2PO4