Siliceous mesocellular foam supported Cu catalysts for promoting non-thermal plasma activated CO2 hydrogenation toward methanol synthesis

Abstract

Electrified non-thermal plasma (NTP) catalytic hydrogenation is the promising alternative to the thermal counterparts, being able to be operated under mild conditions and compatible with green electricity/hydrogen. Rational design of the catalysts for such NTP-catalytic systems is one of the keys to improve the process efficiency. Here, we present the development of siliceous mesocellular foam (MCF) supported Cu catalysts for NTP-catalytic CO₂ hydrogenation to methanol. The findings show that the pristine MCF support with high specific surface area and large mesopore of 784 m²·g⁻¹ and ∼8.5 nm could promote the plasma discharging and the diffusion of species through its framework, outperforming other control porous materials (viz., silicalite-1, SiO₂, and SBA-15). Compared to the NTP system employing the bare MCF, the inclusion of Cu and Zn in MCF (i.e., Cu₁Zn₁/MCF) promoted the methanol formation of the NTP-catalytic system with a higher space-time yield of methanol at ∼275 µmol·g_cat⁻¹·h⁻¹ and a lower energy consumption of \(26.4\ \text{kJ}\cdot \text{mmol}_{\text{CH}_{3}\text{OH}}\!^{-1}\) (conversely, ∼225 µmol·g_cat⁻¹·h⁻¹ and \(\sim71\ \text{kJ}\cdot \text{mmol}_{\text{CH}_{3}\text{OH}}\!^{-1}\), respectively, for the bare MCF system at 10.1 kV). The findings suggest that inclusion of active metal sites (especially Zn species) could stabilize the CO₂/CO-related intermediates to facilitate the surface reaction toward methanol formation.