INFRARED STUDIES OF NITRIC-OXIDE ADSORPTION ON REDUCED AND SULFIDED P-NI-MO AL2O3 CATALYSTS/

A series of P-Ni-Mo/Al2O3 catalysts with varying phosphorus content, p repared by co-impregnation, was studied by infrared spectroscopy of ni tric oxide adsorption on their reduced and sulfided form. It was found that small concentrations of phosphorus (1 to 3 wt.-% P2O5) increased reducibility and sulfidability of nickel and molybdenum. A red shift of the band of nitric oxide adsorbed on molybdenum is observed for sul fided samples with low phosphorus content compared to phosphorus free. In the samples with high phosphorus contents (above 4 wt.-% P2O5) red ucibility and sulfidability of nickel and molybdenum decreases. A blue shift of the band of nitric oxide adsorbed on molybdenum is observed and three types of nickel species are found with different degree of r eduction/sulfidation in the sulfided form of these samples.