Bifunctional mesoporous organic–inorganic hybrid silica for combined one-step hydrogenation/esterification Original Research Article

Bifunctional mesoporous organic–inorganic hybrid silicas with platinum and propylsulfonic acid group (Pt/SBA15-PrSO3H) were synthesized and tested for the combined one-step hydrogenation/esterification (OHE) reaction, which was employed as a model reaction for catalytic upgrading of biomass-derived bio-oil. The model reagents used were acetic acid and acetaldehyde. Different catalyst synthesis procedures were investigated and compared by varying the functional group incorporation method, platinum loading, reducing agent, etc. The textural and chemical properties of the catalysts made by the different synthesis procedures were characterized and compared with reactivity results. The need to create the organic acid sites prior to platinum incorporation was demonstrated. The efficacy of the bifunctional catalyst system for combined hydrogenation/esterification was demonstrated. Interestingly, the bifunctional Pt/SBA15-PrSO3H catalyst exhibited superior esterification activity with about twice the acetic acid turnover number relative to that with the monofunctional SBA15-PrSO3H catalyst. By combining metallic Pt nanoparticles with strong acid sites, this bifunctional mesoporous hybrid catalyst improved OHE activity and, therefore, has potential for application in the catalytic upgrading of bio-oil.