In-situ preparation of porous carbon-supported molybdenum dioxide and its performance in the oxidative desulfurization of thiophene

Molybdenum dioxide (MoO 2 ) supported on porous carbon (MOPC) for the oxidative desulfurization of thiophene was prepared by in situ procedure, where MoO 2 was obtained from thermal conversion of the mixture of polyvinyl alcohol and ammonium molybdate tetrahydrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that formation of MoO 2 from bulk MoO 3 involved direct reduction from Mo(VI) to Mo(IV) while the surface reduction followed Mo(VI) to Mo(V) and finally to Mo(IV). Hexagonal-based MoO 2 platelets were observed to take shape with rising calcination temperature by scanning electron microscope test. Compared with the turnover frequency of MoO 3 (2.96 × 10 −2  h −1 ), MOPC calcinated at 700 °C for 90 min exhibited a much higher turnover frequency of 6.15 × 10 −2  h −1 on oxidative desulfurization of thiophene. The improved desulfurization efficiency of MOPC would be attributed to the more free electrons and smaller steric hindrance in MoO 2 .