Selective oxidation of benzyl alcohol to benzaldehyde with molecular oxygen was studied over sol-derived alumina supported bimetallic Au-Ru and Au-Ir (nominal atomic ratio 1:1) with respect to Au, Ru and Ir monometallic catalysts in both calcined and subsequently reduced states with and without equimolar K2CO3 in toluene at 80 °C. The Au and after an induction period also Au-Ru and Au-Ir samples had good activity and selectivity in the presence of K2CO3, the monometallic Ir and Ru ones showed negligible activity. The different pretreatments did not cause large difference in the catalytic performance, except the Ir containing samples, which were more active in reduced state. The samples were characterized by TEM, STEM-EDS, UV-Vis spectroscopy, XRD and TPR. The surface of the catalysts was investigated by XPS and CO adsorption followed by infrared spectroscopy. We confirmed the interaction between Au and both second metals, and a strongly decreased CO adsorption on gold in the bimetallic samples compared to the monometallic one. Based on the reaction rates related to the estimated Au and second metal surfaces in the bimetallic and corresponding monometallic catalysts synergetic effect is suggested for the calcined and reduced Au-Ru and reduced Au-Ir catalysts in reaction with base addition.
- Benzyl alcohol oxidation
ASJC Scopus subject areas
- Process Chemistry and Technology
- Physical and Theoretical Chemistry