Nanosized samarium modified Au-Ce0.5Zr0.5O2 catalysts for oxidation of benzyl alcohol

Abstract

In this study, Au-Ce0.5Zr0.5O2 (Au-CeZr) and Sm modified AuCeZr catalysts were synthesized by organic deposition-precipitation method using gold acetate and samarium acetate as Au and Sm precursors and tetrapropyl ammonium hydroxide as precipitating agent. The synthesized nanocrystalline Au-CeZr and Sm modified Au-CeZr materials found be effective catalysts for benzyl alcohol oxidation at low reaction temperatures. The catalysts were characterized by XRD, SEM, TEM, DRIFT spectra after pyridine adsorption, N2-physisorption, XPS and H2-TPR techniques. The Au nanoparticles are highly dispersed on CeZr support and XRD reflections due to presence of Au metal were not observed for the samples which contained less than 1.0 wt% Au. The XPS and H2-TPR results revealed that at lower Au loadings, strong Au-CeZr interaction resulted an easy exclusion of surface oxygen ions in Au-CeZr and Sm-Au-CeZr catalysts. Pyridine adsorption results indicated an increase of Lewis acid sites of the CeZr support after Au deposition and Sm modification. The 2.0Sm-0.5Au-CeZr catalyst is most active and selective catalysts for benzyl alcohol oxidation among the synthesized catalysts due to optimum loading of Au and Sm. An optimal surface acidity and redox properties is accountable for the improved catalytic activity of 2.0Sm-0.5Au-CeZr catalyst in the benzyl alcohol oxidation.