Review of catalysis and plasma performance on dry reforming of CH4 and possible synergistic effects

Global warming has received much public concern and carbon dioxide utilization has been considered as one of viable approaches to reduce the CO2 emissions and alleviate global warming. Dry reforming of methane (DRM) is regarded as potential technique to reduce anthropogenic (greenhouse gases) GHGs emissions. Both catalysis and plasma technologies have been applied for DRM to investigate the CO2 and CH4 conversion as well as syngas generation efficiency. For catalysis, noble metal catalysts exhibit good activity but the cost is too high. Ni-based catalysts are usually investigated and several methods of modifying are postulated to enhance their DRM performance including better metal-support interaction, basicity of catalyst and smaller metal cluster size. However, catalysis needs to be operated at a high temperature which results in high energy consumption. Moreover, coke deposition leads to deactivation of catalyst which also limits the lifetime of catalyst. Plasma reforming which can be operated at a wide range of temperature (from room temperature to over 1000 °C) is another technique for DRM. Both non-thermal plasma and thermal plasma are proved to effectively convert CO2 and CH4 into syngas. However, the energy utilization efficiency is still low and relatively low syngas selectivity results in low syngas generation efficiency. Thus, combination of catalysis and plasma can be an alternative to integrate the advantages of catalysis and plasma. Plasma catalysis is proved to have synergistic effects to improve the syngas generation efficiency, since catalysis and plasma can improve the performance of each other. Plasma can enhance catalysis activity and durability, while the existence of catalyst promotes electron density in plasma and energy utilizing efficiency is expected to improve. In this study, the mechanisms of catalysis promotion are described, the synergistic effects between catalyst and plasma are elucidated, and possible approaches to optimize DRM are proposed.