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 °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 °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.