Recovery of phenol and acetic acid from glass fibre reinforced thermoplastic resin using catalytic pyrolysis process on ZSM-5 zeolite catalyst and its kinetic behaviour

Abstract

Glass fibre-reinforced thermoplastic (GFRP) is the composite material of choice for engineers to improve their design, save expenses, and achieve sustainability goals, what leads to generation of a big quantity of GFRP waste (during production or as an end-life-product) that needs to be disposed of safely. In order to valorise GFRP waste, this research aims to recover phenol and acetic acid as high-added value chemical and energy products from the millions of tons of GFRP waste produced annually during the catalytic pyrolysis process. The experiments were performed on glass fibre-reinforced poly(methyl methacrylate)-PMMA (GF/PM) as a common and commercial thermoplastic resin in five stages. In the first stage, the thermal decomposition of the milled feedstock over different percentages of ZSM-5 zeolite catalyst to feedstock in the ranges 0.5-5 wt.% (w/w) was performed using TGA. The generated volatile products from TGA were analysed using TG-FTIR and GC/MS in the second and third stages, respectively. The fourth stage was used to study the kinetic behaviour of catalytic pyrolysis of the feedstock with different catalysts and at different heating conditions using isoconversional models. In the last stage, the experimental thermal decomposition curves were simulated numerically. The results showed that ZSM/GF/PM can decompose significantly in the ranges 320-460 ˚C. Meanwhile, 2 wt.% of catalyst-to-GF/PM ratio was sufficient to recover more than 48% of phenol, 23% of acetic acid, 19% carbon dioxide compounds at 30˚C/min with high intensity of aromatic benzene. Also, this batch gave a higher kinetic complexity in terms of activation energy in the ranges 100-200 kJ/mol (linear models) and 230-440 kJ/mol (nonlinear models). These results confirm that involvement of 2 wt.% ZSM-5 zeolite catalyst in the pyrolysis of GF/PM has a big impact on the formulated volatile components and their potential upscaling.