Improvement of aromatics production from catalytic pyrolysis of cellulose over metal-modified hierarchical HZSM-5

Abstract Metal modification on hierarchical HZSM-5 produced by alkaline desilication was adopted to improve aromatics production from catalytic pyrolysis of cellulose. The influence of alkali concentration in the desilication on catalytic performance of zeolites was first studied. Mild alkaline treatment preserved the micropore structure and acid sites of zeolites when introducing mesopores, while further increase of alkali concentration destroyed the micropores and acidity. The HZSM-5 desilicated by 0.3 M NaOH solution had the best catalytic performance, which increased the aromatics production and BTX selectivity. Then, metal (Fe and Ga) modification on the optimal zeolite was used to further improve the catalytic performance. Fe modification showed negative effect on aromatics production while Ga modification had the positive. Both Fe and Ga modification increased the selectivity of monoaromatics at the expense of polyaromatics. Furthermore, Fe modification mainly enhanced the production of BTX, while Ga modification promoted the formation of both BTX and alkylbenzenes.