Zsm-5 Modified Hfox for Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol: Insight into the Effect of Si Doping

Abstract

Metal oxide catalysts with inherent stability and well-defined structures confer unique advantageous for catalytic transfer hydrogenation (CTH) of furfural (FAL) to furfuryl alcohol (FOL). In this study, ZSM-5 molecular sieve with varying Si/Al ratios was incorporated to modify the HfOx during hydrothermal synthesis. Interestingly, the molecular sieve exhibited distinct behavior compared to conventional carriers, harnessing its inherent porous structure to enhance specific surface areas or support amorphous ions. The Si component of ZSM-5 dissolved and infiltrated the HfOx, thereby increasing exposure to acidic sites by impeding complete condensation. Additionally, Hf+ acquired enhanced Lewis acidity due to electron withdrawal from its surroundings by Si. This modification of HfOx accelerated the conversion of FAL to FOL through CTH reaction, resulting in a significant enhancement in catalytic activity. The Si/Al ratio can be precisely adjusted to control the extent of Si doping, and HfOx@ZSM-5-(260) demonstrated exceptional performance with over 99% of FAL conversion and FOL yield under 160 °C and 1 h. These findings present an intriguing approach for modifying oxide catalysts in CTH reactions.

Keywords: Furfural, Furfuryl alcohol, hafnium oxide, Si doping, catalytic transfer hydrogenation