Use of CO₂ and nylon as the raw materials for flammable gas production through a catalytic thermo-chemical process

Synthetic textiles have offered a chance to enhance the quality of life since their invention. Nonetheless, the massive generation/accumulation of synthetic textile waste (STW) indeed poses numerous environmental problems. To offer a strategic disposal platform to valorize STW into flammable gas, the thermo-chemical processing of STW was studied in this work. Pyrolysis of STW was particularly studied using CO₂ as a raw material to produce more syngas (H₂ and CO). To this end, prior to the pyrolysis test, the main constituents in STW were determined as nylon 6. This study also found that a monomer of nylon 6 (caprolactam) could be recovered from pyrolysis of STW. However, separation of caprolactam could be challenging considering the complex compositional matrixes of STW pyrolytic oil. To enhance the formation of CO stemming from CO₂, catalytic pyrolysis of STW over Ni/SiO₂ was tested. The catalytic capability of Ni-based catalyst led to the enhanced conversion of CO₂ into CO in line with H₂ production and degradation of pyrolytic oil. The production of syngas from CO₂-assisted catalytic pyrolysis was 7 times larger than the reference one arising from increased CO formation by catalytic reaction of CO₂ with pyrolytic products over the catalyst. CO₂ also offered a great chance to suppress catalyst deactivation by suppression of coke deposition or removal of coke deposited on the catalyst surface. All experimental findings of this study could offer an effective guideline for a thermo-chemical disposal platform for nylon while mitigating a hazardous potential in ecosystems. Copyright © 2021 The Royal Society of Chemistry.