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

Abstract

Molybdenum dioxide (MoO2) supported on porous carbon (MOPC) for the oxidative desulfurization of thiophene was prepared by in situ procedure, where MoO2 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 MoO2 from bulk MoO3 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 MoO2 platelets were observed to take shape with rising calcination temperature by scanning electron microscope test. Compared with the turnover frequency of MoO3 (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 MoO2.