Development of doped-TiO2/WO3 photocatalysts for methane conversion into value-added chemicals coupled with hydrogen evolution from water

Abstract

With the increasing concern about environmental issues and climate change, the negative impact of methane emission rates has attracted considerable attention. Methane, as the principal constituent of natural gas, has been recently used as a fuel and is an important raw material in many industrial chemical processes. The dissociation of the first C-H bond in methane is considered the rate-limiting step prior to its activation and to achieve this, temperature of at least hundreds of degress Celsius is normally needed. Recently, a growing number of researches focusing on photocatalytic non-oxidative coupling of methane (PNOCM) under mild conditions has been observed. PNOCM systems have been considered a compelling approach for sustainable and economically technology to produce high-added value chemicals (such as ethane and ethylene) and hydrogen due to its advantages of low temperature of operation, low pressure, energy-saving and environmental protection. By employing efficient photocatalysts with appropriate active sites, methane conversion reactions that are thermodynamically unfavorable can be feasibly mediated by solar energy and produce high chemical potential products. Therefore, exploring low- or room-temperature methane conversion systems is a promising approach to lower the energy comsumption and the reactor cost for commercial applications. However, slow progress in discovering new and prospective catalysts to circumvent problems associated with dependence of high temperatures, low selectivity and stability have hindered further development. We aim to synthesize doped-TiO2/WO3 with the presence of different co-catalysts to obtain efficient photocatalysts for PNOCM. To date, studies focusing on the kinetic mechanism of photocatalytic methane conversion in gas phase are quite insufficient. To address the studies and the outcomes of the research, advanced techniques will be used for better understand the mechanisms that take place during PNOCM reactions for designing photocatalysts with better quantum efficiencies. (AU)