Catalytic pyrolysis of Alhagi sparsifolia Shap biomass over HZSM-5: Thermal behavior, kinetics, thermodynamics and evolved products

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.