Ti/Zr/O Mixed Oxides for the Catalytic Transfer Hydrogenation of Furfural to GVL in a Liquid-Phase Continuous-Flow Reactor

Abstract

This work aims to develop an efficient catalyst for the cascade reaction from furfural to γ-valerolactone in a liquid-phase continuous reactor. This process requires both Lewis and Brønsted acidity; hence, a bifunctional catalyst is necessary to complete the one-pot reaction. Ti/Zr/O mixed oxide-based catalysts were chosen to this end as balancing metal oxide composition allows the acidity characteristics of the overall material to be modulated. Oxides with different compositions were then synthesized using the co-precipitation method. After characterization via porosimetry and NH3-TPD, the catalyst with equimolar quantities of the two components was demonstrated to be the best one in terms of superficial area (279 m2/g) and acid site density (0.67 mmol/g). The synthesized materials were then tested using a plug flow reactor at 180 °C, with a 10 min contact time. Ti/Zr/O (1:1) was demonstrated to be the most promising catalyst during the recycling tests as it allowed obtaining the highest selectivities in the desired products (about 45% in furfuryl isopropyl ether and 20% in γ-valerolactone) contemporaneously with 100% furfural conversion.