Direct Non-Oxidative Conversion of Methane over Metal-Containing Zeolites: Main Strategies for Shifting the Thermodynamic Equilibrium (A Review)

Natural gas can play a significant role in the long-term transition from fossil fuels to green energy. Methane, the main component of natural gas, is an attractive resource for the co-production of hydrogen and value-added chemicals. One promising approach for valorization of methane is its direct non-oxidative conversion to hydrogen and hydrocarbons. However, in view of the harsh reaction conditions required for the activation of methane, one of the key challenges hindering the commercialization of this process is low stability of the catalyst structure and its active sites. A potential solution is lowering the reaction temperature. From a practical perspective, the reaction temperature cannot be lowered unless the thermodynamic equilibrium is shifted towards the reaction products. Such a shift can provide acceptable levels both of methane conversion and of the yield of valuable products. This review presents a summary of the current approaches to enhancing methane conversion and aromatics yield based on shifting the thermodynamic equilibrium during the conversion of methane to hydrogen and hydrocarbons.