Catalytic pyrolysis of cellulose using ZnZrO/HZSM-5 catalysts for light aromatics

Abstract

ABSTRACT The HZSM-5 catalytic pyrolysis of cellulose to aromatics is one of the effective ways to realize its high-value utilization. However, HZSM-5 has strong acidity, and its microporous structure leads to low mass transfer of reactants and products. The ZnZrO/HZSM-5 catalysts with adjustable pore structure and acidity were developed for efficient conversion of cellulose to aromatics. Their physicochemical properties were characterized by XRD, N2 adsorption, SEM and NH3-TPD and their performance was studied. As the ratio of ZnZrO increases from 0 to 1, the pore size increased from 1.98 nm to 6.77 nm. When the ZnZrO ratio was 0–0.25, the Bronsted acid sites decreased, and the difference was not significant at 0.25–0.375. When the ZnZrO ratio is 0.375–1, the Bronsted acid sites continued to decrease. The random repeated exposure of cellulose cracking gas in ZnZrO and HZSM-5 made more opportunities for aromatization and cracking. ZnZrO-0.125 showed the performance. The yield of BTEX was 83.15%, and the selectivity was 95.15%. Compared with the traditional HZSM-5, the yield increased by 5.7% and the selectivity increased by 11.38%.