Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcohol
The materials containing gold nanoparticles supported on pure and Ce, Ti, or Fe-modified hexagonal mesoporous silica were prepared and their structural and electronic properties were studied by XRD, TEM, XPS, and N2 adsorption techniques. The materials were shown to be effective heterogeneous catalysts for the liquid-phase aerobic oxidation of benzyl alcohol in methanol solutions. It was found that the modifiers significantly improve the catalytic properties of supported gold particles and allow performing the selective one-pot oxidative esterification of benzyl alcohol resulting in methyl benzoate. The modified catalysts exhibited high activity (turnover frequencies of up to ca. 1000 h−1), selectivity to methyl benzoate (up to 95%), and stability (turnover numbers of up to ca. 4300). Ce and Ti were found to be more effective promoters as compared with Fe in terms of catalyst stability.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (130 K)Download as PowerPoint slideHighlights► The one-port aerobic oxidative esterification of benzyl alcohol was studied. ► Nanoparticles of gold supported on hexagonal mesoporous silica promote this reaction. ► The modification of the support with Ti, Fe or Ce improves the catalytic performance. ► Ce and Ti modified materials show high catalytic activity, selectivity and stability. ► Methyl benzoate was obtained in a 92% yield with a turnover number of ca. 4300.
Journal: Applied Catalysis A: General - Volume 397, Issues 1–2, 30 April 2011, Pages 145–152