Boosting methanol production via plasma catalytic CO2 hydrogenation over a MnOx/ZrO2 catalyst

Abstract

Hydrogenation of carbon dioxide (CO₂) to methanol is considered as a potential approach to simultaneously mitigate global warming and energy crisis issues. As an effective and economic oxide, MnO_x is widely used as a promoter in catalytic CO₂ hydrogenation, but it is rarely directly used as a catalyst in this reaction due to its poor activity. Herein, boosted methanol production over a MnO_x/ZrO₂ catalyst was carried out via plasma-assisted catalytic CO₂ hydrogenation at ambient temperature and pressure. A space–time-yield value of methanol of 4.5 mg_MeOH g_cat⁻¹ h⁻¹ and a synergy factor of 87 were achieved with a stable performance over five cycles and 36 h. The in situ diffuse reflectance infrared Fourier transform spectroscopy and gas-phase FTIR spectra results indicate that the key intermediates over the MnO_x/ZrO₂ catalyst shifted from (bi)carbonates species to HCOO and CH₃O species in the plasma-assisted process. The methanol formation route was thus established. The beneficial effect of the plasma was the generation of excited species (such as , CO₂⁺, and H), which could be effectively hydrogenated to HCOO and then further to CH₃O by the favorable catalytic effect of MnO_x. This study proposed a new strategy for catalyst design and methanol synthesis at ambient temperature and pressure.