Enhancing the ketonization ability of CeO₂ for deoxygenation of biomass-derived sugars by Fe doping

Ketonization of oxygenated compounds in pyrolytic products of biomass is an effective means for deoxygenation and upgrading of bio-oils. However, the ketonization potential of biomass-derived sugars and the mechanism underneath remain unclear. On this basis, a series of Fe doped CeO₂ catalysts were synthesized and employed for catalytic ketonization of xylan. Characterization of the catalysts proved the successful formation of the Fe-CeO_x solid solution. Doping an appropriate amount of Fe (20–33%) ions on CeO₂ could obviously increase the number of oxygen vacancy and basic sites by up to 56.31% and 29.6%, respectively. During the catalytic reaction of xylan, pure CeO₂ exhibited a good ketonization ability during xylan pyrolysis, and the introduction of a certain amount of Fe further enhanced the ability. The highest yield of ketones was obtained by 33%Fe-CeO₂, which was 38% higher than pure CeO₂. The selectivity to linear ketones (acetone and 2-butanone) reached a maximum of 85% for 57%Fe-CeO_x. Thus, oxygen-rich compounds had been converted to low oxygen containing and high-quality ketone components. Introducing Fe into CeO₂ favored the production of ethylene glycol rather than 2,3-dihydroxy propanal, and thus promoted the yield of acetone. This investigation provides fundamentals for the deoxygenation of biomass through catalytic ketonization, aiming at the production of value-added ketone products.