A Cascade Process for CO2 to Methanol Driven by Non-Thermal Plasma: A Techno-Economic Assessment

The non-thermal plasma-driven cascade process for CO2-to-methanol conversion shows significant potential in the field of green methanol synthesis. This process innovatively couples a plasma activation module with a catalytic synthesis module via a multi-stage pressurization device, establishing an efficient two-step pathway that converts CO2 into methanol via a CO intermediate. Such an arrangement establishes an energy conversion system characterized by both low carbon emissions and high efficiency. This work involved an initial technical evaluation employing a custom-built, lab-scale apparatus. The optimum parameters determined through this assessment were a plasma input voltage of 40 V combined with a subsequent reaction temperature of 240 °C. Operation at these specified parameters yielded a CO2 conversion of 48%, with the methanol selectivity and production rate reaching 40% and 502 gMeOH·kgcat−1·h−1, respectively. Furthermore, industrial-scale process design and scale-up were performed, accompanied by process simulation using Aspen Plus and a subsequent techno-economic evaluation. The results indicate that, compared to the conventional direct CO2 hydrogenation process, the proposed cascade route can reduce the capital investment by approximately 17%.