Systematic analysis of the gallium ions and structure-directing agents in the preparation of NiW HDS catalysts over mixed oxides of Al₂O₃-TiO₂

Abstract

In this study, we prepared Al2O3-TiO2 (AT) mixed oxides to synthesize NiW catalysts for sulfur removal reactions. AT support samples were prepared using various surfactants. Additionally, gallium atoms (2.4 wt%) were introduced as an additive to coat the outer surface layers of the AT support that lacked Al3+ or Ti2+ cations. The characterization results showed substantial differences in textural properties, chemical composition, and surface acidity. XPS and High-resolution TEM results demonstrated that the NiW/AT-L-Ga sample has a better combination of dispersion, sulfidation, and promotion among materials. Sulfided NiW/AT-L-Ga catalyst had the highest catalytic activity. After incorporating Ga, XPS observed that the activity could be associated with an increase in the NiWS active phase; however, including a surfactant in the synthesis of the support allowed an increase in the amount of NiWS phase. Active phase was modeled considering the HRTEM results for the slab length, revealing the atoms at the border susceptible to promotion.