The integrated process of CO₂ hydrogenation and catalytic methanol synthesis under plasma conditions holds great potential for CO₂ conversion from waste gases. This process connects a dielectric barrier discharge (DBD) plasma reactor and a methanol synthesis fixed-bed reactor through a pressurization device, achieving the stepwise conversion of CO₂ to CO and then to methanol, thereby establishing a low-carbon and high-efficiency energy conversion system. This study experimentally investigated the key parameters influencing the CO₂ hydrogenation process in the DBD plasma reactor and the methanol synthesis process in the fixed-bed reactor. The results show that in the plasma reaction, discharge power, discharge gap, gas flow rate, and gas composition significantly affect CO₂ conversion efficiency. In the methanol synthesis process, the CO/CO₂ mixed feed exhibits superior catalytic performance compared to pure CO₂. The optimal operating conditions for the integrated process are a plasma voltage of 40 V and a downstream reaction temperature of 240 °C, under which the system achieves the best overall performance.

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 g_MeOH${·\mathrm{kg}}_{\mathrm{cat}}^{-1}$·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%.