Distribution, migration, and removal of N-containing products during polyurethane pyrolysis: A review

Guanyi Chen; Tiecheng Liu; Pengpeng Luan; Ning Li; Yunan Sun; Junyu Tao; Beibei Yan; Zhanjun Cheng

doi:10.1016/j.jhazmat.2023.131406

Distribution, migration, and removal of N-containing products during polyurethane pyrolysis: A review

J Hazard Mater. 2023 Jul 5:453:131406. doi: 10.1016/j.jhazmat.2023.131406. Epub 2023 Apr 12.

Authors

Guanyi Chen¹, Tiecheng Liu², Pengpeng Luan², Ning Li³, Yunan Sun⁴, Junyu Tao⁴, Beibei Yan⁵, Zhanjun Cheng⁶

Affiliations

¹ School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China; Tianjin Key Lab of Biomass/Waste Utilization, Key Laboratory of Efficient Utilization of Low and Medium Energy of Ministry of Education, Tianjin Engineering Research Center for Organic Wastes Safe Disposal and Energy Utilization, Tianjin University, Tianjin 300072, China; School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, PR China.
² School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China.
³ School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China; Tianjin Key Lab of Biomass/Waste Utilization, Key Laboratory of Efficient Utilization of Low and Medium Energy of Ministry of Education, Tianjin Engineering Research Center for Organic Wastes Safe Disposal and Energy Utilization, Tianjin University, Tianjin 300072, China. Electronic address: liningec@tju.edu.cn.
⁴ School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, PR China.
⁵ School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China; Tianjin Key Lab of Biomass/Waste Utilization, Key Laboratory of Efficient Utilization of Low and Medium Energy of Ministry of Education, Tianjin Engineering Research Center for Organic Wastes Safe Disposal and Energy Utilization, Tianjin University, Tianjin 300072, China.
⁶ School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China; Tianjin Key Lab of Biomass/Waste Utilization, Key Laboratory of Efficient Utilization of Low and Medium Energy of Ministry of Education, Tianjin Engineering Research Center for Organic Wastes Safe Disposal and Energy Utilization, Tianjin University, Tianjin 300072, China. Electronic address: zjcheng@tju.edu.cn.

PMID: 37084514
DOI: 10.1016/j.jhazmat.2023.131406

Abstract

Due to the wide applications of polyurethane (PU), production is constantly increasing, accounting for 8% of produced plastics. PU has been regarded as the 6th most used polymer in the world. Improper disposal of waste PU will result in serious environmental consequences. The pyrolysis of polymers is one of the most commonly used disposal methods, but PU pyrolysis easily produces toxic and harmful nitrogen-containing substances due to its high nitrogen content. This paper reviews the decomposition pathways, kinetic characteristics, and migration of N-element by product distribution during PU pyrolysis. PU ester bonds break to produce isocyanates and alcohols or decarboxylate to produce primary amines, which are then further decomposed to MDI, MAI, and MDA. The nitrogenous products, including NH3, HCN, and benzene derivatives, are released by the breakage of C-C and C-N bonds. The N-element migration mechanism is concluded. Meanwhile, this paper reviews the removal of gaseous pollution from PU pyrolysis and discusses the removal mechanism in depth. Among the catalysts for pollutant removal, CaO has the most superior catalytic performance and can convert fuel-N to N2 by adsorption and dehydrogenation reactions. At the end of the review, new challenges for the utilization and high-quality recycling of PU are presented.

Keywords: Catalysis; Nitrogenous compounds; Polyurethane; Pyrolysis.

Publication types

Review