Hydroprocessing of dibenzothiophene, 1-methylnaphthalene and quinoline over sulfided NiMo-hydroxyapatite-supported catalysts

Abstract

Hydroprocessing of dibenzothiophene, 1-methylnaphthalene and quinoline was studied in a batch reactor at 340 °C and 7 MPa H 2, over sulfided NiO–MoO 3 catalysts supported on calcium-deficient hydroxyapatite materials, enriched or not with Al ions, and aluminium phosphate AlPO 4. On those catalysts, reaction schemes for hydrodesulfurization of dibenzothiophene, hydrogenation of 1-methylnaphthalene and hydrodenitrogenation of quinoline were found to be similar to those already reported for sulfided NiMo catalysts supported on γ-alumina. However, the catalytic activity was significantly improved by using calcium-deficient apatites, particularly for the catalyst referred to as NiMo/ACP-1.5 that contains 1.5 wt.% Al ions, although its specific surface area was lower than that of an industrial alumina supported catalyst. This increase in activity would result from the presence of superficial defects oxygen vacancies and HPO 4 2− species, which would ease the dispersion of the NiMo phase. Moreover, the existence of correlations between the reaction rates for hydrodesulfurization of dibenzothiophene, hydrogenation of 1-methylnaphthalene, hydrodenitrogenation of quinoline and reduction of dimethyldisulfide into methanethiol confirm that the nature of the catalytic sites was the same, whatever the chemical reaction concerned, hydrogenation of aromatic rings or hydrogenolysis of C–S, C–N and S–S bonds.