Recent Advances in Dry Reforming of Methane via Photothermocatalysis

Abstract: During the development of traditional industries, large amounts of greenhouse gases have been emitted due to the increasing consumption of fossil energy. CH4 and CO2 account for more than 98% of greenhouse gas emissions, and the conversion of CH4 and CO2 into high value-added chemicals has attracted extensive attention from both industry and academia. Dry reforming of methane (DRM) can co-convert CH4and CO2 into syngas, which can be further converted into various value-added fuels and chemicals through Fischer-Tropsch synthesis. The dry reforming of methane into syngas by thermal catalysis provides an effective strategy for the consumption of both CH4 and CO2, which is beneficial for alleviating environmental problems such as global warming. However, a high-intensity energy input is needed at high temperatures owing to the thermodynamic limitations of the DRM reaction and catalyst instability caused by coke formation. Environmentally friendly photocatalytic technology can make the DRM reaction proceed under mild conditions. However, its development is greatly restricted owing to the low utilization rate of sunlight and low reaction conversion rate. Recently, photothermocatalysis has been widely used in various fields. Many studies have shown that under relatively mild conditions, photothermocatalysis of DRM can achieve promising catalytic performance and effectively convert solar energy into chemical energy. Photothermocatalysis can greatly increase the reaction rate of photocatalytic DRM without a high energy input. In addition, the introduction of light is beneficial for the thermal catalysis of DRM by reducing the reaction activation energy, inhibiting coke formation, and reversing the water-gas shift reaction. In this paper, the advantages and disadvantages of thermal catalysis, photocatalysis, and photothermal catalysis of DRM are first discussed. Then, recent research progress in photothermocatalysis of the DRM reaction, especially the application of different metal-based catalysts (Ni, Pt, Rh, Ru, and Co) is summarized. Localized surface plasmon resonance effects, types of carriers, elimination of coke formation, and suppression of the reverse water-gas shift reaction are briefly mentioned. Finally, the future challenges and new perspectives on the photothermocatalysis of DRM are highlighted, including high utilization of sunlight, catalyst long-term stability, reactor optimization, and the photothermocatalytic mechanism.