A Study of NiP/SiO and MoP/SiO Catalyst Passivation.

The effect of various oxygen passivation treatments on a 15 wt% MoP/SiO and a 15 wt% NiP/SiO catalyst is reported. Approximately 85 % of the MoP was re-oxidized when the MoP/SiO catalyst was passivated or simply exposed to air, whereas only about 40 % of the NiP was re-oxidized when the NiP/SiO catalyst was treated similarly. A second reduction of the catalysts after the passivation, followed by CO uptake measurements, showed an increase in CO uptake in the case of the MoP/SiO and a significant loss in CO uptake on the NiP/SiO when compared to the CO uptake measurements of the corresponding non-passivated samples. The oxidized species that resulted from the passivation of the NiP/SiO were much more easily reduced than those on the MoP/SiO. The loss in CO uptake observed in the case of the NiP/SiO is attributed to sintering and/or restructuring of the NiP during the second reduction step. Graphical Abstract: [ABSTRACT FROM AUTHOR]