Catalytic pyrolysis of Alhagi sparsifolia Shap biomass over HZSM-5: Thermal behavior, kinetics, thermodynamics and evolved products
Zhitong Yao, Jiayao Tong, Jingjing Jiang, Qiang Yu, Obid Tursunov, Xiaobo Wang, Jie Liu, Wei Qi
Abstract
Biomass feedstocks and their complex components can yield a wide range of pyrolysis products. Furthermore, catalytic pyrolysis has emerged as a promising technology for the conversion of biomass into high-value chemicals. This study investigated the pyrolysis behavior, kinetics, thermodynamics and evolved products of Alhagi sparsifolia Shap ( A. sparsifolia ), a biomass from arid area. Its catalytic pyrolysis over HZSM-5 catalyst was carried out and compared with the non-catalytic pyrolysis. The results indicated that the mass loss decreased from 69.35 to 74.98 wt% to 48.78–58.53 wt% upon the addition of HZSM-5. Both degradation process occurred in three stages: below 200 ℃, 200–500 ℃, and 500–900 ℃. The presence of HZSM-5 lowered the peak temperatures from 352.8 to 377.7 ℃ to 328.7–331.4 ℃. In addition, the average apparent activation energy decreased from 102.79 to 78.00 kJ mol −1 . The master-plots method indicated that the experimental curves for both conversions were consistent with the diffusion-based model. Positive ΔH and ΔG values confirmed that both decompositions were endothermic and non-spontaneous. However, the inclusion of HZSM-5 enhanced the reactivity of the sample while reducing the energy requirement. GC-MS analysis revealed that the products formed at peak temperatures of 365 ℃ for non-catalytic pyrolysis were mainly phenols and ketones. In contrast, the catalytic pyrolysis at 335 ℃ simplified the product composition and favored the formation of acetic acid and furfural with higher selectivity. • Thermal behavior, kinetics and thermodynamics of A. sparsifolia were studied. • Apparent activation energy reduced by 24.11 % after adding HZSM-5. • Catalytic pyrolysis improved the products selectivity. • Addition of catalyst increased the reactivity of sample.