Selective hydrotreating of FCC gasoline over KCoMoP/Al2O3 catalysts prepared with H3PMo12O40: Effect of metal loading

Abstract

d-Kx-CoMoP/Al2O3 catalysts with different Mo loading (d) equal to 2, 3 and 5 at Mo/nm2 and varied up to 2 of K/Mo molar ratio (x) were prepared using H3PMo12O40, CoCO3, KOH and citric acid. The catalysts were characterised by low-temperature N2 adsorption, temperature-programmed desorption of NH3, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and tested in hydrotreating of heavy FCC gasoline. It was found that the introduction of a higher amount of K and Mo in the KxCoMoP catalyst led to enhancement of metal sulfidation and formation of KCoMoS phase species with large sizes. Maximal selectivity factor and low RON less after hydrotreating of FCC gasoline was achieved over 5-K1.5CoMoP catalyst. Both 3-K1.5CoMoP and 2-K1.5CoMoP catalysts contained lower Mo loading had reduced HDS and HYDO activities compared with 5-K1.5CoMoP analog having the same K/Mo ratio. However, 2-K1.5CoMoP and 3-K1.5CoMoP catalysts had a higher selectivity factor, then 5-CoMoP analog having higher Mo loading and similar morphology of active phase species. The introduction of potassium decreased the apparent activation energy and pre-exponential factor of the both HDS and HYDO reactions. It was concluded that the alkali metal changes the properties and concentrations of both types of the active sites on the KCoMoS2 slabs by a similar mechanism.