Characteristics of Gases From Co-Pyrolysis of Sawdust and Tires

Abstract

The composition and characteristics of permanent gases that evolve during co-pyrolysis of sawdust and waste tires were observed. Gas composition was determined by gas chromatography, whereas gas characteristics were studied by pyrolysis–Fourier transform infrared (Py-FTIR) spectroscopy. Results show that as co-pyrolysis temperature and the proportion of sawdust in the mixture of biomass and waste tires increase, the gas yield increases, but the relationship between the addition of sawdust and gas yield is nonlinear. A synthetic effect exists among the co-pyrolysis gases. When the mass ratio of sawdust to tires is 1:2, and pyrolysis temperature is 600°C at a flow rate of 90 ml min−1, gas yield reaches 30.3 wt%. The mass fraction accounted for by ignited gases (such as CO, H2, CH4, C3H8, C3H6, and C2H4) is nearly 46% with a gross calorific value (GCV) of 17.9 MJ Nm−3, indicating that the gases may act as fuel gas. As a desulfurizer, ZnO removes 92% of H2S in the gaseous products. The content of H2S is below 10 × 10−9 g g−1 when ZnO is used during co-pyrolysis. Py-FTIR analysis shows that gases containing saturated C–H bonds (such as CH4 and C3H8) evolve first, followed by CO2, CO, and water vapor, and finally, vinyl-containing gases such as C3H6. It confirms that gases produced by co-pyrolysis of biomass and tires are completely utilized as resources while they are disposed. This has a great significance for sustainable supply of energy.