Carbothermal synthesis of porous silicon carbide using mesoporous silicas

Samples of crystal modifications of porous silicon carbide were obtained by carbothermal method using carbon precursors (sucrose, carbon) and aerosil or mesoporous silicas molecular sieves SBA-3, SBA-15, KIT-6, and MCF as silicon sources. Porous β-SiC samples obtained from carbon–silica composites are characterized by high structural and sorption characteristics ( S_BET up to 410 m ²/g, V_pore up to 1.0 cm ³/g). High hydrogen adsorption capacity of silicon carbide samples based on KIT-6 (up to 1.24 wt% at 77 K and 1 atm.), considering low adsorption energy ( |Δμ0|H2) up to 2.3 kJ/mol for SiC vs. ca. 5.0 kJ/mol for carbon), was determined. The highest ever reported value among the existing porous materials was observed for specific adsorption of H ₂ by SiC (specific adsorption on the pore surface, ρ up to 15 μmol/m ²) corresponding to almost complete filling of the surface with hydrogen in the examined conditions (77 K, 1 atm.).