Synergistic effect of biomass and polyurethane waste co-pyrolysis on soot formation at high temperatures

Soot is an important toxic pollutant generated during high-temperature incineration of solid waste (i.e., biomass and plastic waste) under air-lean conditions, and has a great impact on flame radiation. The main objective of this work is to study the synergistic effect of biomass and polyurethane co-pyrolysis on soot formation at high temperatures (1100-1250 °C). The effects of temperature, biomass species, and co-pyrolysis ratio on the yield, morphology, composition and reactivity of soot particles are studied. Results show that under controlled co-pyrolysis conditions, the measured soot yield from co-pyrolysis of biomass and polyurethane is lower than the theoretical value by weight average, while the particle size distribution tends to concentrate on a smaller diameter range. The degree of synergistic effect increases with the increasing biomass ratio (0-50 wt%) and decreasing pyrolysis temperature. Wood in co-pyrolysis presents a stronger synergistic effect on soot yields than straw co-pyrolysis does. Degree of synergistic effect on soot oxidation reactivity depends much on the biomass addition ratio but less on pyrolysis temperature. At 10 wt% straw addition ratio, co-pyrolysis exerts a negative synergistic effect on soot oxidation reactivity, while the synergistic effect turns significantly positive when the straw addition ratio increases to 50 wt%.