Factors Influencing Synergistic Pyrolysis of Biomass and Polypropylene for Alcohols and Hydrocarbon Production

Results are presented on the co-pyrolysis of different blends of rapeseed stalk and plastic polypropylene (100:0, 75:25, 50:50, 25:75 and 0:100) using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS), independently. The effect of temperature (450, 550 and 650 °C) on the synergistic effect between rapeseed stalk and polypropylene at different blend ratios as well as on the yield and amounts of alcohols and hydrocarbons produced are presented. The thermogravimetric analysis results showed that at the same temperature, increase of polypropylene in the mixture, gradually increased the intensity and rate of pyrolysis reaction. The weight loss data revealed improved pyrolysis during the process. The Fourier transform infrared spectroscopy results showed that the transmittance of ketones, esters and acids increased while the content of ketones, esters and acids decreased with increased polypropylene in the mixture. The pyrolyzer-gas chromatography/mass spectrometry results showed that temperature and feedstock mixture ratio had an impact on the yield and amounts of alcohols and hydrocarbons. The pyrolysis effect was most favorable at 550 °C temperature and rapeseed stalk/polypropylene mixture ratio of 1:3. These results provide some practical insights on clean energy recovery from mixtures of agricultural residues and waste plastics using thermochemical conversion.