Partial Oxidation of Methane to Methanol Using Bismuth-Based Photocatalysts

Bismuth-based photocatalysts, Bi 2 WO 6, BiVO 4, and coupled Bi 2 WO 6 /TiO 2 –P25, have been synthesized by a facile hydrothermal method, characterized, and evaluated for the first time for the selective photooxidation of methane to methanol. Several conditions were used in order to better comprehend the reaction mechanism. The obtained BiVO 4 is, among the others, the most promising photocatalyst for this reaction, displaying higher CH 3 OH selectivity and being more stable than the others. When Bi 2 WO 6 was coupled with TiO 2, the methane conversion increased; however, overoxidation of CH 4 to CO 2 predominates. A similar effect is observed when electron scavengers such as O 2 or Fe 3+ were introduced in the photoreactor as a result of the formation of highly oxidant radicals.