Introducing mesopore and regulating Al distribution for improving catalytic performances of ZSM-5 in furfuryl alcohol to levulinic acid

Catalytic valorization of biomass into chemicals and fuels plays a key role in order to achieve net-zero greenhouse gas emissions. Herein, a series of hierarchical ZSM-5 zeolites were synthesized by the post-treatment method to transform furfural alcohol (FAL) to levulinic acid (LA). ZSM-5 obtained from tandem alkaline treatment (0.2 M NaOH) and acid washing (0.1 M HCl), denoted as ZSM-5-OH 0.2 -H, exhibited the highest activity, affording 76.2% LA yield in 9:1 acetone–water mixed solvents at 393 K for 0.5 h. The enhanced adsorption capacity and acid accessibility of FAL on zeolite mediated by the introduction of mesopores, as well as the reduced secondary reactions of the generated LA due to few Al atoms in straight and sinusoidal channels (as confirmed by UV–vis diffuse reflectance), were responsible for the outstanding catalytic performance of ZSM-5-OH 0.2 -H. The structure–activity relationship revealed that regulating the porous structure and Al distribution of ZSM-5 was an effective strategy to enhance its hydrolytic performance of FAL to LA. Moreover, ZSM-5-OH 0.2 -H could be reused for three reaction cycles without significant loss in catalytic activity.