An insight on the role of La in mesoporous WO3 for the photocatalytic conversion of methane into methanol

• Selective photooxidation of CH4 over ordered mesoporous WO3/La was studied.
• WO3/La showed excellent photocatalytic activity for CH4 conversion.
• Modification of the surface of WO3 was crucial to improve the methanol selectivity.
• Enhanced activity is ascribed to an increase of H2O and HO− on catalyst surface.

One of the great challenges in the photocatalytic oxidation of methane into methanol is to find a suitable catalyst that allows an increase in the selectivity without diminishing the total conversion, since the main feature that rules the yield of this reaction is the overoxidation to CO2. Ordered mesoporous metal oxides show large surface area and good light harvesting, resulting in efficient catalysts for many photocatalytic applications. With this in mind, a new highly active photocatalyst, La doped mesoporous WO3, was examined. The production of methanol over WO3/La was approximately 2 times higher than that of pure WO3 while the CO2 rates were significantly decreased, resulting in higher methanol selectivity. This improvement was mainly due to lanthanum contributing to maintaining the mesoporous structure during calcination treatment and increasing the generation of OH groups on the surface of WO3. Their availability plays a major role in the CH4 conversion into methanol.

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