Mechanism Study on Nitrogen Migration and Catalytic Denitrification during the Pyrolysis of Lysine and Tryptophan

Abstract

Catalytic fast pyrolysis can effectively solve the pollution and treatment problems of sewage sludge to realize the green recycling of biomass waste energy. The study on the mechanism of nitrogen migration is a crucial part of the conversion of sewage sludge. Herein, two amino acids of lysine with linear amines and tryptophan with aromatic nitrogen-containing heterocycles were used as typical model compounds to investigate the pyrolysis mechanism and nitrogen migration behavior. The results revealed that lysine mainly underwent two routes: one was to cyclize itself to lactam and cleavage twice with the gradual dehydrogenation to form stable nitrogen-containing heterocycles; the second was first decarboxylation and then cleavage with gradual dehydrogenation to form nitriles. The first route was easier to proceed at low temperatures, while the second route took up more proportions at high temperatures. Tryptophan was converted gradually to stable indoles after decarboxylation, deamination, dehydrogenation, and denitrification. Based on the full understanding of the nitrogen migration mechanism of lysine and tryptophan, the catalytic denitrification mechanism over dolomite, limonite, and HZSM-5 modified with Ni loading catalysts was also explored.

Fast Pyrolysis of Tea Waste under a Hydrogen-Rich Atmosphere: A Study on Nitrogen Evolution and Green Ammonia Production

“…It was observed that the amine–N yield decreased slightly before 600 °C but then showed a sharp decrease by 15.57 wt % from 600 to 800 °C. This tendency of amine–N in tar was consistent with Zhao et al’s findings during the pyrolysis of some amino acids. The formation of amine–N can be attributed to the thermal cracking of more labile N–A in fuels .…”

“…As shown in Table S2, a large amount of N–heterocyclic compounds was found in tea waste pyrolysis tar, such as pyrrole, pyridine, indole, and their substitutes/derivatives. The discrepancy among these N–heterocyclic compounds mainly resulted from amino acids with different chemical structures. , As Zhao et al reported, lysine with linear amines was prone to form stable pyrrole and pyridine, while tryptophan with aromatic N–heterocycles was mainly converted into stable indole compounds. Heterocyclic–N increased with the temperature initially in both the Ar- and H 2 -rich atmospheres until 600 °C and then slowly declined to 20.91 wt % in an Ar atmosphere, while it shrank swiftly to 9.74 wt % in a H 2 -rich atmosphere at 800 °C.…”

Kinetic nitrogen isotope effects of 18 amino acids degradation during burning processes

“…For example, the side chain of Trp is an indole group, which maintains stability at high temperatures. Consequently, Trp predominantly forms tryptamine, 1H-indole, and 3-methyl-1H-indole via decarboxylation (Pathway 3, Table S6 ) or deamination (Pathway 4, Table S6 ) during combustion 30 , 34 . Because the phenyl ring side chain of Phe also remains stable during combustion, it primarily degrades through two pathways: direct decarboxylation to form benzeneethanamine, and simultaneous removal of the amino and carboxyl groups to produce toluene 31 .…”

Interplay of curing and thermal degradation in epoxy resins cured with amino acids: Influence of the maximum curing temperature on the network structure, crystal morphology and mechanical properties

“…Deamination is a condensation reaction that involves the formation of ammonia through the condensation of an amino group with a hydrogen atom. 42 This reaction has been observed in amino acids such as L-glutamine, L-glycine, and L-arginine. 36 Both reactions result in the formation of volatile compounds with low molecular weight, namely water and ammonia.…”

“…This reaction has been observed in amino acids such as l ‐histidine, l ‐arginine, and l ‐aspartic acid during thermal degradation. Deamination is a condensation reaction that involves the formation of ammonia through the condensation of an amino group with a hydrogen atom 42 . This reaction has been observed in amino acids such as l ‐glutamine, l ‐glycine, and l ‐arginine 36 .…”