Selective hydrodeoxygenation of bio-oil derived products: acetic acid to propylene over hybrid CeO2–Cu/zeolite catalysts†
Conversion of acetic acid, the light oxygenate from biomass pyrolysis, to propylene can be achieved via keto-hydrodeoxygenation (KHDO) over hybrid CeO2–Cu/zeolite catalysts at >573 K under atmospheric H2. The catalyst containing CeO2 and Cu/HY (25 wt% of Cu/HY) was employed to obtain up to 85% conversion of acetic acid with 49% selectivity to propylene. Acetone, propylene and propane are obtained via ketonization–hydrogenation–dehydration over the three-component catalyst, while ethanol, acetaldehyde, ethylene, ethane and ethyl acetate can also be produced from hydrogenation–dehydration over Cu/zeolites alone. The catalyst containing Cu/HY provides higher selectivity to olefin products, as compared to that containing Cu/HZSM-5. The reaction is suppressed by the presence of water. Nevertheless, high catalyst stability (>60 hours on stream) can be obtained. The KHDO can be applicable for the conversion of acetic acid, a biomass derived product, to hydrocarbons using a sequential bed system of the three-component catalyst and HZSM-5 catalyst.