Granular Ni–Mo–W bulk hydrotreating catalyst: the effects from precursor calcination

This paper presents a study on the effect of the Ni–Mo–W precursor calcination (300, 450 and 500$^\circ$C) on properties of granulated bulk Ni–Mo–W catalysts. The Ni–Mo–W precursor and bulk catalysts were studied by XRD, nitrogen adsorption-desorption method, CHNS analysis, thermal analysis, Raman spectroscopy, UV-Vis DR spectroscopy, HRTEM and XPS. It is shown that the increase in calcination temperature of the precursor to 500$^\circ$C leads to stepwise decomposition of citric acid, transformation of active metals and re-structurization of the samples. Active metals in sulfide catalysts are present in the bulk mixed or individual sulfides and interact with alumina binder to form “NiMoS-like” sulfide phase. Increased crystallinity of the precursor results in the enlargement of bulk nickel particles, capsulation of Mo and W and their rounding by Ni atoms. Catalysts testing in hydrotreatment of SRVGO demonstrates that the best choice of temperature regimes is 300$^\circ$C for the precursor.