Base-Free Benzyl Alcohol Aerobic Oxidation Catalyzed by AuPdNPs Supported on SBA-15 and TiO2/SBA-15 Mesoporous Materials

It is known that the oxidative reactions of alcohols are sensitive to the characteristics of the catalyst, in such a way that the properties of the support are as important as those of the metallic phase. We consider the functionalization of support as a strategy to improve the catalytic performance in these reactions. We investigated the influence of the modification of the Si/Ti ratio of the TiO2@SBA-15 support (RSi/Ti = 75, 50 and 25) on the catalytic performance of the synthesized materials: Me/SBA-15, Me/TiO2@SBA-15 (Me = AuNPs or AuPdNPs). The techniques of XRD, adsorption, and desorption of N-2, ICP-OES, XPS, SEM, and TEM were used for characterization. The structure of the SBA-15 was maintained in all supports and catalysts and a significant reduction in particle size was observed in the modified support S25 (AuPd/SBA-15: 18.96 +/- 12.48 nm; AuPd/S25 (RSi/Ti = 25): 3.14 +/- 0.85 nm). All Au and AuPd catalysts performed well, showing activities > 53% in 2.5 h. However, bimetallic catalysts achieved greater prominence, reaching activities of 20 to 90% and selectivity > 90% for benzaldehyde in 0.5 h. Among them, the AuPd/S25 catalyst stood out with significant activity and selectivity (90%), in addition to good stability in successive reuse experiments. [GRAPHICS] .