Experimental and DFT study on the migration and transformation mechanism of nitrogen during the pyrolysis of food waste. (15th June 2023)

• Record Type: Journal Article
• Authors: Qing, Mengxia; Zheng, Yang; Liu, Liang; Huang, Sibiao; Zeng, Hongliang; Tian, Hong; Xiang, Jun
• Is Part Of: Fuel. Volume 342(2023)
• Publication Date: 2023-06-15
• Subjects: Food waste -- Density functional theory -- Pyrolysis -- NOx precursor; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.127773
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: The evolution of nitrogen in pyrolysis oil and pyrolysis gas during the pyrolysis of food waste was investigated. NH3 mainly comes from the detachment of amino groups. HCN is mainly derived from the dehydrogenation of amino acids and the cleavage of N -containing heterocycles and nitriles. N -containing heterocycles are the main N -containing substance in pyrolysis oil. N -containing heterocycles are generated by de-H2 O or intermolecular de-H2 O of amino acids or condensation reactions of amino acids with small molecules. Abstract: Pyrolysis technology is an effective way to realize the reduction and recycling of food waste (FW), but the generation of N -containing substances has a great impact on the quality of pyrolysis products and the environment. The present study mainly focused on the migration and transformation mechanism of N during the pyrolysis process of FW, which was investigated by TG-FTIR, GC–MS, and DFT calculation. The experimental results show that NH3 and HCN are the main N -containing gas products, and the N -containing substances in the pyrolysis oil are mainly N -containing heterocycles (21.82%), nitriles (6.43%), and amides (4.00%) at 500 ℃. The proteins in food waste are cleaved into various amino acid molecules at temperatures above 300 ℃. Some amino acid molecules generate NH3 and HCN by removing various groups. Some other amino acid molecules generate N -containing heterocycles, nitriles, amides, and various other N -containing substances by intramolecular de-H2 O or intermolecular de-H2 O reactions of amino acids or condensation reactions of amino acids with small molecules and transfer to the pyrolysis oil. As the temperature increases, most of the N -containing heterocycles and nitriles will be cleaved and generate HCN.