Microwave-assisted one-pot sol–gel synthesis of tungsten silicate microspheres with dispersed WOx and their activity in ethanol dehydration

Abstract

This study introduces a novel microspherical W–SiO₂ heterogeneous catalyst for alcohol dehydration, prepared via an innovative microwave-assisted condensation synthesis method. The process involves the microwave-assisted preparation of a hybrid tungsten naphthalene dicarboxylate-based precursor solution, which is subsequently condensed with (3-aminopropyl)triethoxysilane in a single step—eliminating the need for separate silica support preparation, as required in conventional impregnation methods. After calcination at 550 °C, the resulting amorphous and porous microspheres contain highly dispersed tungsten species (with loadings of 2, 6, and 12 wt%), with no crystalline WO₃ phase detected, even at the highest loading. Compared to a 12 wt% WO₃/SiO₂ catalyst prepared via conventional impregnation, the W–SiO₂ microspheres exhibit higher catalytic activity and ethylene selectivity in ethanol dehydration at 420 °C. Notably, the 2W–SiO₂ catalyst achieved the highest initial ethylene productivity per mole of tungsten (520 mmol mmol_W⁻¹ h⁻¹), maintaining 230 mmol mmol_W⁻¹ h⁻¹ after 1000 minutes on stream, indicating high long-term stability. In terms of mass-specific performance, the 12W–SiO₂ catalyst reached 133 mmol g⁻¹ h⁻¹, outperforming other comparable previously reported tungsten–silica catalysts.