Recent advancements in integrating CO2 capture from flue gas and ambient air with thermal catalytic conversion for efficient CO2 utilization

Capturing CO2 and converting it into valuable chemicals and fuels have been regarded as a pivotal strategy in addressing the environmental challenges of ever-growing CO2 emissions. Combining CO2 capture and conversion through material or process integration can eliminate the energy-intensive steps such as separation, compression, and transportation across a wide range of space and temperatures. The flue gas at high temperatures > 300 degrees C can be handled with dual-function materials consisting of sorbents and catalysts. The dual-function materials combine CO2 capture and conversion through material integration, converting CO2 with reactions such as methanation, reverse water-gas shift, dry reforming of CH4, and oxidative dehydrogenation of propane. On the other hand, capturing CO2 from air directly requires a long time to collect enough CO2 for the subsequent conversion reaction. Consequently, direct air capture will likely combine with the conversion reactions in stepwise operations. The low latent heat in CO2 from direct air capture makes it more suitable for reactions at a mild condition (< 250 degrees C), and stepwise operation allows the separate control of the capture and conversion conditions. Herein, we reviewed recent advancements in coupling CO2 capture from flue gas and ambient air with thermal catalytic conversion. We discussed the requirements for materials, reactor configuration, and process operation for capturing and converting CO2 from these sources and proposed that future research should focus on enhancing the efficiency, scalability, and sustainability of CO2 capture and conversion technologies and optimizing the process design.