Thermo-catalytic co-pyrolysis of waste biomass and non-recyclable polyethylene using ZSM-5 into renewable fuels and value-added chemicals

Abstract

The present study deals with thermo-catalytic co-pyrolysis of peanut shells (PS) and non-recyclable polyethylene (NRPE) using ZSM-5 at varying ratios (5, 10 and 15 wt%). A tubular fixed bed reactor is used to pyrolyse at 500 °C, 50 °C min−1 heating rate and 100 mL min−1 inert gas flow rates. The feedstock was characterized via proximate analysis, elemental analysis, higher heating value (HHV), biochemical analysis, thermogravimetric analyser (TGA), Fourier transforms infrared spectroscopy (FTIR) viscosity, density, Gas chromatography-mass spectrometry (GC-MS), BET surface area, water holding capacity (WHC). Co-pyrolysis results confirmed maximum liquid yield (34.50 %) at 10 wt% of NRPE; however, adding 10 wt% ZSM-5 again boosted the liquid oil yield by 7.87 wt%. Pyrolytic oil characterization results confirmed that adding NRPE and ZSM-5 at 10 wt% decreased viscosity, acidity, and density. However, carbon content, heating value and ash content increased. FTIR examinations of PS confirmed hydrocarbons, acids, water, and oxygenated compounds. GC-MS results were confirmed by adding NRPE and ZSM-5 at 10 wt%; hydrocarbon and furfural increased by 5.31 and 5.46 %, whereas 6.01 % acids and oxygenated compounds decreased, respectively. The results of the char characterisation further supported the findings that adding NRPE (10 wt%) to PS enhanced carbon content and HHV by 11.86 % and 4.35 MJ kg−1 and decreased ash content, oxygen content, and bulk density by 0.75 %, 10.21%, and 71.98 kg m−3, respectively.