Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

Abstract

This work aims to study the catalytic co-pyrolysis of waste wind turbine blades (WTB: consists of fiberglass/unsaturated polyester resin) and woody biomass (WB) over ZSM-5 and Y-type zeolite catalysts for the production of benzoic acid. The experiments were performed on an equal combination of WTB and WB (WTB/WB) and a fixed amount of catalyst (50 wt%) using a thermogravimetric (TG) analyser at 10, 20 and 30 °C/min. The evolved products from the catalytic co-pyrolysis process were recognized using TG-FTIR and GC/MS. The kinetic and thermodynamic characteristics of catalytic co-pyrolysis was studied using various linear and nonlinear approaches. Also, the decomposition curves were predicted mathematically using an artificial neural network algorithm. The results revealed that the mixture was decomposed in the presence of both catalysts in the form of dual decomposition peaks at 361–374 °C and 428–443 °C, respectively. Based on TG-FTIR results, the C[dbnd]O stretching and carbon dioxide clusters were their main functional groups. While the GC-MS analysis revealed that the released vapours were completely free of toxic styrene (the main compound of resin) and the catalytic co-pyrolysis treatment succeeded in converting it into highly abundant benzoic acid, especially at 10 °C/ min, with an estimated 71.4 % (ZSM-5) and 64 % (Y-type). Whereas the activation energy was estimated at 262–295 kJ/mol (ZSM-5) and 319–357 kJ/mol (Y-type) with almost similar reaction complexity when compared to the case of absence of catalysts. Finally, the developed ANN algorithm showed high efficiency in predicting TG decomposition zones for both WTB/WB mixtures over zeolite catalysts with R2 more than 0.99. These results demonstrate that WB and zeolite catalysts can be used for upgrading the pyrolysis oil of WTB and eliminate its toxic styrene and convert it into benzoic acid and other aromatic hydrocarbons compounds (such as benzene, alanine, and 2-Propanamine).