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

Abstract

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 FePOx/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% FePOx/SiO2 aerogel were 18.3 and 4.2 times, respectively, higher than those of 4 wt% FePOx/SiO2 particles. These composites manifest significant selectivity towards the direct catalytic oxidation of CH4 to HCHO.