Nano-H-ZSM-5 with Short b-Axis Channels as a Highly Efficient Catalyst for the Synthesis of Ethyl Levulinate from Furfuryl Alcohol

For the ethanolysis of biomass-derived furfuryl alcohol (FA) to value-added ethyl levulinate (EL), the development of an efficient solid acid catalyst is very important for industrial application with high FA concentration. Herein, a H-ZSM-5 catalyst with nano b-axis channels (NB-H-ZSM-5) was synthesized and used for the conversion of FA. Detailed catalyst characterization proved that the NB-H-ZSM-5 catalysts (Si/Al = 25∼125) with ∼70 nm b-axis channels were successfully prepared. The NB-H-ZSM-5 catalyst with Si/Al = 75 showed the highest activity. Its structural characteristics allowed for fast diffusion of reactants and products and full utilization of active sites, which endowed it with higher activity compared to commercial H-ZSM-5 (C-H-ZSM-5). Its moderate acidity effectively inhibited the polymerization of FA even at a high FA concentration of 20 wt %. The spent catalyst was easily regenerated by coke burn-off to give a good recyclability. Furthermore, based on the proposed reaction network, a method of physically mixing the NB-H-ZSM-5 (75) catalyst with a small amount of Amberlyst-15 was proposed to further increase the EL yield from 64.7 to 82.1% at an FA concentration of 6 wt %.