Ultra-high specific surface area spherical FePO_x/SiO₂ aerogel with excellent mechanical properties for the highly selective direct oxidation of CH₄ to HCHO

Silica aerogels, characterized by their high porosity and substantial specific surface area, are suitable for applications as catalysts or catalyst supports. The simultaneous attainment of a substantial specific surface area and robust mechanical properties in aerogel materials remains a formidable challenge in material synthesis. Spherical FePO_x/SiO₂ aerogel materials were synthesized employing a combination of heating reflux, the sol-gel technique, and supercritical ethanol drying. These composites demonstrate an exceptional specific surface area, uniformly dispersed active components, shape controllability, and superior mechanical strength. A noteworthy enhancement in both specific surface area (1175 m²/g) and compressive modulus (7.56 MPa) surpasses many findings reported in extant literature. Under conditions of a reaction temperature at 650 °C and a flow rate of 97.5 mL/min, the HCHO selectivity and yield for 4 wt% FePO_x/SiO₂ aerogel were 18.3 and 4.2 times, respectively, higher than those of 4 wt% FePO_x/SiO₂ particles. These composites manifest significant selectivity towards the direct catalytic oxidation of CH₄ to HCHO.