Bubble-template synthesis of WO3 center dot 0.5H(2)O hollow spheres as a high-activity catalyst for catalytic oxidation of benzyl alcohol to benzaldehyde

摘要

Although significant progress has been made in WO3 hollow spheres, it is still a challenge to synthesize WO3 center dot 0.5H(2)O hollow spheres. Herein, a strategy for the preparation of well-shaped WO3 center dot 0.5H(2)O hollow spheres was developed by a facile bubble-template method using urea as a foaming agent in the solvothermal process with EtOH-H2O mixture solvent. In this process, the growth of WO3 center dot 0.5H(2)O nanoparticles is limited by N-containing organic compounds, thus these nanoparticles tend to agglomerate along the surface of bubbles (CO2 and NH3) to fabricate hollow spheres with pores formed in the wall, and after low temperature calcination, pure WO3 center dot 0.5H(2)O hollow spheres are obtained. The obtained WO3 center dot 0.5H(2)O hollow spheres exhibit enhanced activity in catalytic oxidation of benzyl alcohol to benzaldehyde: the conversions of benzyl alcohol, 4-methyl, 3-methyl, 2-methyl, 4-bromo and 4-nitro benzyl alcohol are 99.2%, 95.0%, 97.1%, 86.7%, 98.0%, 90.6%, respectively, and the selectivities to corresponding benzaldehydes are all greater than 98%. The high activity of WO3 center dot 0.5H(2)O hollow spheres could be attributed to surface -OH groups and the hollow and porous structure.