Synthesis Gas Production from Co-Pyrolysis of Straw Biomass and Polyethylene Agricultural Film and Kinetic Analysis

The co-pyrolysis of straw biomass and polyethylene film at different mass ratios was carried out in a small fixed-bed reactor with CaO as catalyst. The resulting synthesis gas production, liquid and solid products, and pyrolysis kinetics were studied by gas chromatography and thermogravimetric analysis. The results showed that with increasing proportion of plastic in the feedstock, co-pyrolysis had a synergistic effect on the CH₄ yield, reaching as high as 3.124 mol CH₄/kg feedstock, while the H₂ and CO yields continuously decreased. Comparing the experimental and theoretical yields of synthesis gas, the trends for CO and CH₄ were consistent, but those of H₂ and CO₂ differed widely. Examining the influence of element mass ratios in the feedstock on the synthesis gas composition, it was found that the biomass and plastics affected the formation of oxygen- and hydrogen-containing gases, respectively. The activation energy and pre-exponential factor showed increasing and decreasing trends, respectively, when the feedstock proportions and heating rate changed. Fitted linear correlation coefficients for all pyrolysis stages exceeded 0.99.