Mesoporous pseudo-ordered alumina doped with yttrium as a support for NiW hydrodesulfurization catalysts

In recent years, publications on how to improve hydrodesulfurization catalysts have decreased considerably. However, the presence of sulfur compounds in oil cuts continues to increase and still represents a challenge to comply with environmental regulations. In this direction, improving hydrodesulfurization catalysts is of paramount importance. The present study focuses on combining two approaches to modify the alumina surface and bulk properties, namely, using an ordered porous structure and doping it with yttrium. We synthesized AlY-x (x as 0, 0.5, 1.0, and 1.5 yttrium substitutions in a alumina unit cell) materials via a one-pot solgel route assisted by citric acid and P-123. The samples were calcined at 800 °C and 1000 °C to determine their stability. The support samples were subsequently used to prepare NiW/AlY-x catalysts to be applied in hydrodesulfurization (HDS) reactions via 3-methyl-thiophene (3MT), dibenzothiophene (DBT), as naphtha and diesel sulfur model compounds. The results indicate that yttrium promotes stability, enhances textural properties, increases the CO₂ adsorption capacity and changes the acidbase properties of the supports. In the case of the NiW/AlY-x catalyst, the presence of yttrium results in better dispersion, decreasing the WS₂ slabs and improving the participation of Ni in the nonstoichiometric NiWS active phase . These improvements led to selectivity resulting almost exclusively from the direct desulfurization route. Among all the catalysts tested, NiW/AlY-1.0 resulted in approximately 4.6 times greater activity than the yttrium-free sample.