Enhancement of Pt catalytic activity in the hydrogenation of aldehydes
Bifunctional mesoporous organic–inorganic hybrid silica involving platinum and propylsulfonic acid groups (Pt/SBA15-PrSO3H) have been demonstrated to have potential for catalyzing the combined one-step hydrogenation/esterification (OHE) reaction. This reaction provides a model system for the catalytic upgrading of biomass-derived bio-oil. In this study, efforts were made to improve the catalytic performance of the catalyst for aldehyde hydrogenation, which was determined to be rate limiting in the OHE reaction with the bifunctional catalyst. STEM analysis coupled with hydrogen chemisorption results showed that aqueous reduction–deposition using formaldehyde as the reducing agent produced highly dispersed platinum nanoparticles located within the mesopores of SBA15. XPS and UV–vis demonstrated that the metal sites were not fully activated due to insufficient reducing capability of the formaldehyde. Elevated temperature treatment of the as-prepared materials in either an air or H2 environment was examined. These treatments significantly increased the acetaldehyde hydrogenation activity, especially in the case of H2 treatment. XPS and H2-TPD results demonstrated that Pt species were further reduced and as a result, hydrogen was activated more readily.
Graphical abstractStudies were performed to enhance the hydrogenation performance of metal sites on mesoporous silicas catalysts (Pt/SBA15), in order to provide guidance for the further enhancement of bifunctional catalysts (Pt/SBA15-PrSO3H) to be used in one-step hydrogenation/esterification, which is a model reaction for the catalytic upgrading of bio-oil.Figure optionsDownload full-size imageDownload high-quality image (191 K)Download as PowerPoint slideHighlights► Reductive deposition of Pt yields high metal dispersion on SBA15. ► Pt deposited by reductive deposition can be activated at lower temperatures. ► Hydrogen activation can occur at lower temperatures with the activated catalyst. ► High activity for aldehyde hydrogenation was achieved.
Journal: Applied Catalysis A: General - Volume 406, Issues 1–2, 18 October 2011, Pages 81–88