Solvent-free mechanochemical conversion of CO2 into mesoporous SiC: a green route to high-performance catalysts

Abstract

Silicon carbide (SiC) is a critical material across structural, electronic, and catalytic applications; however, its conventional synthesis via the Acheson process is highly energy-intensive, operating at 2200-2400 degrees C with low carbon efficiency. Herein, we report a novel, solvent-free mechanochemical synthesis of mesoporous SiC using CO2 as a sustainable carbon feedstock and SiO2/Mg as earth-abundant precursors. Through a two-step ball-milling process, SiO2 is first reduced by Mg to form Mg2Si, which then spontaneously reacts with CO2 to form SiC and MgO, achieving a high CO2 conversion efficiency of 84% at only 10% of the energy cost of conventional methods. Density functional theory (DFT) calculations confirm the thermodynamic feasibility of CO2 activation on Mg2Si. The produced mesoporous SiC exhibited excellent durability and served as a highly stable support for Ni catalysts in dry reforming of methane (CH4 + CO2 -> H2 + CO), maintaining performance over 100 hours with minimal coke formation. This work introduces a green, scalable route for synthesizing high-value SiC, integrating CO2 utilization and catalyst development under the principles of green chemistry.