Thermochemical textile recycling: Investigation of pyrolysis and gasification of cotton and polyester

Abstract

With a rising textile consumption worldwide comes in increased flow of textile waste. The existing recycling methods, mechanical and chemical recycling, are insufficient in many ways, and therefore only a small share of all textile waste is utilized for making new textiles or other materials. It is therefore of interest to investigate additional recycling methods, in this thesis gasification and pyrolysis are considered. The first part of the report aimed to investigate mechanical and chemical recycling, by identifying suitable feedstocks for these methods, as well as their major limitations. The conclusion was that both methods solely can handle streams consisting of only one fiber type, and that this limits the ability to scale up the recycling, as the textile waste found in municipal solid waste, MSW, is exceptionally heterogeneous. Secondly the report aimed to investigate the possibility to recycle textile waste found in MSW by thermochemical methods. Applications for the gas, liquid and solid product was evaluated and the expected composition of the gas and liquid were investigated by reviewing existing gasification and pyrolysis experiments, as well as by performing new tests of cotton and polyester pyrolysis. As the oxygen content in both cotton and polyester is relatively high, the existing experiments reviewed showed that the dominating specie in the gas produced will be CO2, which lowers the quality of the gas. The focus of the thesis was therefore to recover mono-aromatic compounds from the pyrolysis oil, as these are desired in the chemical industry and can be utilized when manufacturing several chemical compounds.