Efficient hydrodesulfurization catalysts based on Keggin polyoxometalates

Abstract

Bulk and supported hydrodesulfurization catalysts based on Mo and W and containing Co or Ni as promoters and phosphorus as a modifier are prepared through the polyoxometalate route using Keggin type phosphomolybdates and phosphotungstates and tested in the HDS of thiophene at 350-400°C and 1 bar pressure. The corresponding oxidic pre-catalysts retain intact Keggin structure of the parent polyoxometalates and possess Brønsted and Lewis acidity. In the course of sulfidation, the oxidic pre-catalysts transform into an active sulfidic phase with the loss of Keggin structure and catalyst acidity. Catalyst activity increases in the order of supports: SiO2 < TiO2