Evaluation of zeolite catalysts on product distribution during sweet sorghum bagasse catalytic pyrolysis

The catalytic fast pyrolysis (CFP) of sweet sorghum bagasse was carried out in a three-stage tube furnace to achieve high value utilization of sweet sorghum bagasse. The effects of zeolite catalysts (hierarchical HZSM-5, HBeta, HY and HUSY) and pyrolysis temperature (450 °C, 500 °C, 550 °C and 600 °C) were investigated to obtain the relationship between the product distribution of bio-oil and the zeolite properties. The results showed that the relative contents of monocyclic aromatics followed the order: hierarchical HZSM-5 (DS-HZSM-5) > HBeta > HUSY > HY, and the relative contents of polycyclic aromatics followed the order DS-HZSM-5 < HY < HUSY < HBeta. DS-HZSM-5 contributed to the formation of benzenes, obtaining the highest relative content (80.8%), whereas HUSY and HBeta facilitated the formation of naphthalenes with relative contents of 7.4% and 11.2%, respectively. Furthermore, 550 °C was the optimum pyrolysis temperature for the catalysis of DS-HZSM-5, and 450 °C was the most suitable pyrolysis temperature for the catalysis of HBeta, HY and HUSY. The results of this research are important for the utilization of sweet sorghum wastes in view of obtaining high-value chemicals.