Recent progress on unconventional dry reforming of methane processes

• A comprehensive review on unconventional DRM. • Molten liquids mediated DRM is resistant to carbon deposition but with high energy consumption. • Integrated CO2 capture and DRM could handle diluted exhaust gas directly but with poor CO2 capture stability. • Plasma-assisted DRM is active under mild condition but with poor cost-effectiveness. • Super DRM is promising in CO2-rich DRM but with unclear mechanism. Converting CO 2 and CH 4 via dry reforming paves an attractive path for utilizing the two greenhouse gases. Conventional DRM processes, including continuous feeding DRM and chemical looping DRM, suffer from carbon depositions, high energy consumption and poor stability. To overcome these well-known and longstanding drawbacks, a few novel unconventional DRM processes were developed, including molten liquids mediated DRM, integrated CO 2 capture and DRM, plasma-assisted DRM, super DRM, etc. This review comprehensively summarized the recent progress on these unconventional DRM processes from the aspect of catalyst system, technical issues, catalytic performance and mechanism. The unconventional DRM design avoids the impact of carbon deposition on the continuous operation of the process, or provides entry-level technology for specific gas source applications (e.g., CO 2 rich natural gas). Despite its obvious advantages, unconventional DRM currently faces the main challenge of low energy utilization and difficulty in scaling. With the continuous development of technology, unconventional DRM is expected to become an important supplement to DRM industrialization.