(586e) The Performance of PdxAu1-X RCT-SiO2 for the Partial Oxidation of Alcohols: Effects of Molecular Weight and Operating Temperature on Selectivity and Conversion.
Here, we extend the method to investigate the selective oxidation of alcohols on dilute palladium-in-gold alloy nanoparticles supported on a âraspberry colloid templatedâ SiO2 support2 (PdxAu1-x RCT-SiO2). The catalysts were tested in a fixed-bed catalytic reactor at atmospheric pressure after an in situ oxygen treatment, followed by stabilization under reaction conditions at an elevated temperature. At 150Â°C the methanol conversion is nearly 100%, but C2-C4 alcohols show low conversion. Increasing the reactor temperature to 250Â°C increases the conversion of these alcohols to between 60 and 90% with high selectivity to form aldehydes. The product distribution and analysis of residual carbon indicate the importance of carboxylate intermediates that block the reaction at the lower temperature. Additional studies of CO oxidation were utilized to probe active sites of the PdxAu1-x catalysts and their dynamic nature.
The results show broad similarities in mechanism on PdxAu1-x RCT-SiO2 to that observed on npAgAu, but the Pd based catalyst is more active. This similarity points to the generality of the utility of the dilute alloy catalysts for selective catalytic chemistry.
(1) Reece, C.; Luneau, M.; Friend, C. M.; Madix, R. J. Predicting a Dramatic Decline in Selectivity for Catalytic Esterification of Alcohols from van Der Waals Interactions. Angew. Chemie - Int. Ed. 2020, Accepted. https://doi.org/10.1002/anie.202001576.
(2) Luneau, M.; Shirman, T.; Filie, A.; Timoshenko, J.; Chen, W.; Trimpalis, A.; Flytzani-Stephanopoulos, M.; Kaxiras, E.; Frenkel, A. I.; Aizenberg, J.; et al. Dilute Pd/Au Alloy Nanoparticles Embedded in Colloid-Templated Porous SiO2: Stable Au-Based Oxidation Catalysts. Chem. Mater. 2019, 31, 5759â5768. https://doi.org/10.1021/acs.chemmater.9b01779.