NiMoW/P-Al2O3 four-component catalysts with different Mo:W molar ratios and P2O5 contents: the effect of the composition and active phase morphology on the catalytic activity.

NiMoW/P-Al₂O₃ catalysts were synthesized with a different ratio of Mo:W (W-free sample, Mo:W = 2:1, Mo:W = 1:1, Mo:W = 1:2 and Mo-free sample) and various P₂O₅ contents in the carrier (up to 5 wt%). The surface of the sulfide phase of the samples was investigated by means of high-resolution transmission electron microscopy (HR TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of patterns was estimated in the reactions of hydrodesulfurization of dibenzothiophene (DBT) and hydrogenation of naphthalene. The results are presented in the form of three-dimensional diagrams "P₂O₅ content—ratio Mo/W—catalytic activity" or "P₂O₅ content—ratio Mo/W—property". The influence of the phosphorus content on the maximum peak position of the binding energy S2p/1 of the S²⁻ atomic group for the investigated systems is shown. Comparison of the shape of the curve of changes in the binding energy with the previously presented results on the catalytic activity of the samples in the HDS of a vacuum gas oil allows us to conclude that phosphorus is able to change the electronic state of the active phase of the catalysts, which leads to a change in their catalytic activity in the reactions of HDS. [ABSTRACT FROM AUTHOR]