Well-dispersed sulfated mesoporous WO3/SiO2 hybrid colloidal spheres: High-efficiency catalysts for the synthesis of fatty acid alkyl esters

• Mesoporous WO3/SiO2 spheres with a specific surface area 1370 m2/g−1 were prepared.
• The kinetics-controlled formation mechanism of the colloidal spheres was proposed.
• The sulfated mesoporous WO3/SiO2 spheres exhibit excellent catalytic performance.

An effective method in obtaining well-dispersed mesoporous WO3/SiO2 colloidal spheres (WMWCSs) with a specific surface area of 1370 m2 g−1, pore volume of 0.84 cm3 g−1, and pore size of 2.44 nm was developed. This method allows easy control over the morphology, size and dispersity of the hybrid spheres by the variation of synthetic conditions. The formation mechanism on the as-prepared WMWCSs was proposed as well. Treated with sulfuric acid, the resulted WO3/SiO2 colloidal spheres exhibited excellent catalytic activity in the synthesis of biodiesel via the esterification of long-chain free fatty acids (FFAs). A 96.9% conversion of oleic acid was realized under optimized conditions, 3 wt% of catalyst and 6 h of reaction time, while the catalyst suffered no obvious loss in activity for five consecutive runs.

We demonstrate an efficient synthesis of well-dispersed mesoporous WO3/SiO2 colloidal spheres (WMWCSs) with hexadecyltrimethyl ammonium phosphotungstic (W-6) as precursor and hexadecyltrimethyl ammonium bromide (CTAB) as template. The resulted WO3/SiO2 colloidal spheres exhibit a high specific surface area of 1370 m2 g−1 and pore volume of 0.84 cm3 g−1 with pore size of 2.44 nm. The formation mechanism as-prepared WMWCSs was also proposed. Treated with sulfuric acid, the sulfated mesoporous WO3/SiO2 hybrid colloidal spheres (SWMWCSs) were obtained, and the SWMWCSs exhibited excellent catalytic performance in the synthesis of biodiesel via the esterification of long-chain free fatty acids (FFAs).Figure optionsDownload as PowerPoint slide