Effects of various additives on the pyrolysis characteristics of municipal solid waste

Additives can have a significant impact on the pyrolysis process. The effects of three additives (CaO, MSW char and biomass) on the pyrolysis characteristics of municipal solid waste (MSW) were investigated using a fixed-bed reactor. In addition, the effects of additives and temperature on the MSW pyrolysis product yield, the composition of MSW pyrolysis gases, and the composition of MSW pyrolysis tar were investigated using fixed bed reactor, GC-MS and FTIR, respectively. The results showed that the maximum tar yield of the MSW reached 28.73% at 600 °C and the tar yield decreased with increasing amounts of CaO and MSW. The tar yield began to decrease when the additive amount of CaO was 5% and decreased to 23.05% when the additive amount of MSW char (C) was 30%. Synergistic pyrolysis of the biomass and MSW was observed when the additive amount of the pine increased to 75% (with a tar yield of 37.91%). Regarding gas composition, with increasing additives content, the CO₂ yield decreased, while the CO yield increased. According to the FTIR analysis of the tar, CaO enhanced the condensation of the aromatic rings and converted the aliphatic hydrocarbons, while C reduced the oxygenic groups of the tar. The GC-MS results revealed that the additives decreased the yield of carboxylic acid and ethanol, and increased the ester yield. The additives were also found to have a deoxidation effect that decreased the acid content, potentially improving the quality and stability of the tar.