Selective oxidation of renewable biomass has recently generated immense interest. This revived interest is mostly driven by economics and by the need to develop efficient and “green” processes that are less detrimental to the environment. Catalytic selective oxidation is capable of producing a large number of valuable chemical intermediates and products from relatively abundant feedstocks such bio-derived oxygenates (e.g. carbohydrates). Gold and gold alloys have been found to be active for a number of reactions including the selective oxidation of carbohydrates. However, the catalytic activity of supported gold catalysts is highly dependent on the nature of the support and its physiochemical properties, the metal particle size, and the catalyst preparation method. We have shown previously that alloyed Au-Pd NPs with particle size less than 5 nm can be prepared by colloidal synthesis and immobilization on hydrothermally-synthesized nanostructured TiO<sub>2 </sub>and CeO<sub>2 </sub>supports to create reproducible, stable, and highly active selective oxidation catalysts using benzyl alcohol as a model reaction. In this work, the performance of these catalysts for the selective oxidation of biomass-derived glucose has been investigated and show very promising results. The catalytic activity and product selectivity to gluconic acid and glucaric acid were found to be strongly dependent on the Au-Pd bimetallic composition, and the structure and morphology of the support. A strong correlation between the concentration of Au in the alloyed Au-Pd NPs and the formation of deep oxidation products was observed. Furthermore, ceria-supported catalysts were found to be more selective in comparison to titania-supported catalysts. The superior catalytic performance of Au-Pd supported on nanostructured ceria is associated with the physiochemical properties of the ceria supports and the catalyst preparation method, which allowed for controlling the Au-Pd particle size and facilitated high metal dispersion over the surface of the support. Characterisation by TEM, STEM, XPS and XRD revealed very interesting features about these catalysts and helped explain their catalytic performance.

Selective oxidation of glucose using Au-Pd NPs NPs immobilized on nanostructured ceria and titania: Influence of bimetallic composition and support morphology

2019 Fall National Meeting

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