Bioenergy potential appraisal of melon seed shells via catalytic pyrolysis over V/W-ZSM-5: Product analysis, thermokinetics and DFT study

Abstract

This study examined the catalytic pyrolysis of melon seed shell (MSS) using vanadium tungsten modified ZSM-5 (V/W-ZSM-5) through combined experimental and theoretical methods. Thermogravimetric analysis (TGA) with model-free kinetics revealed that the catalyst lowered the activation energy by about 10 % (184–194 kJ mol⁻¹) compared with non-catalytic pyrolysis. Thermodynamic assessment showed reduced entropy (ΔS) values for conversion fractions below 0.7, indicating a more ordered and energy-efficient pathway. Product distribution from Py-GC/MS confirmed enhanced selectivity, with levoglucosan and furfural yields increasing nearly 5-folds and 3-folds, respectively. Density functional theory (DFT) clarified the mechanistic pathways: levoglucosan formed primarily via glucose dehydration, while furfural production followed xylose ring-opening and nucleophilic conversion. Collectively, these findings demonstrate that V/W-ZSM-5 not only improves selectivity toward high-value products but also reduces both kinetic and thermodynamic barriers, highlighting its potential for sustainable biomass valorization.