Effective photocatalytic methane oxidation over the TiO2/methanotrophs system

Abstract

The direct conversion of methane (CH4) to methanol (CH3OH) is a significant but challenging reaction. We present a photocatalytic system composed of brookite mesoporous titanium dioxide and methanotrophs (Methylosinus trichosporium OB3b) for the conversion of CH4 to CH3OH with high activity, selectivity and stability at ambient temperature and pressure. This system obtains the highest CH3OH production rate (15,761 ± 142 μmol g−1 h−1), which is dozens of times higher than most researches and 5 times of the optimal value of photcatalytic CH4 conversion under the same condition. The process achieved nearly 100% selectivity and excellent stability under simulated sunlight irradiation and without any cocatalysts, sacrificial agent or inhibitors. The biocompatibility of semiconductor materials and the contact mode with OB3b have significant impact on the process. Titanium dioxide is used as an exogenous electron donor to greatly promote the conversion activity of CH4 by OB3b under light irradiation. The work has significant pioneering implications for efficient CH4 selective conversion using natural gifts combined with artificial materials.