Plasma-Assisted Catalytic Conversion of Methane at Low Temperatures

The conversion of methane (CH4) to value-added fuels (e.g., alcohol) is a promising technology for clean energy. However, conventional thermal methods of converting CH4 to fuels require high temperatures (700–1100 °C) and have low conversion efficiency and selectivity. Therefore, it is highly desirable to develop novel cost-effective technologies that can convert CH4 to fuels and chemicals at low temperature and atmospheric pressure with improved conversion efficiency, selectivity, and durability of products. The low-temperature or non-thermal plasma-assisted catalytic conversion of CH4 is gaining increasing interest because the plasma species (e.g., electrons) have sufficient energies for producing higher hydrocarbons, alcohols, and oxygenates with higher yields and selectivity while reducing coke formation under mild conditions. The key challenges of this green technology are as follows: increasing conversion efficiency of CH4, design of hybrid plasma reactors with proper catalysts and optimized conditions, addition of efficient oxidants (e.g., O2 or CO2) and diluents, etc., at low temperature and atmospheric pressure. In this regard, the present review aims to provide a comprehensive account of the current development of plasma-assisted catalytic conversion of methane, with focus on conversion efficiency of CH4, selectivity and stability of products, and catalyst durability with the variation in plasmas, electrode design, and reactor configurations. Further, the review presents the current and future challenges.