Formation mechanism of HCN and NH3 during indole pyrolysis: a theoretical DFT study

Ji Liu, Xiaolei Zhang, Bin Hu, Qiang Lu, Dingjia Liu, Changqing Dong, Yongping Yang

Research output: Contribution to journalArticle

Abstract

Coal is a major contributor to the global emission of nitrogen oxides. The NOx formation during coal utilisation typically derives from thermal decomposition of N-containing compounds pyrrole, which usually combines with an aromatic ring in the form of indole. NH3 and HCN are common precursors of NOx from the decomposition of N-containing compounds. In this study, possible pathways of indole pyrolysis to form HCN and NH3 are investigated using the density functional theory (DFT) method. Calculation results indicate that indole pyrolysis has two type of possible initial reactions, which are internal hydrogen transfer and hydrogen homolysis reaction, respectively. The initial reaction mode of indole has a great impact on the subsequent pyrolysis pathway. Additionally, it is shown that indole can produce two nitrogen-containing products, i.e. HCN and NH3. Five pathways will result in the formation of HCN (path-1, path-3, path-a, path-b, path-c), and another two pathways will lead to the NH3 (path-2, path-4). Furthermore, among all the reaction mechanisms of indole pyrolysis, the path-1 is the optimal reaction pathway. During which, indole is converted to a diradical intermediate, then the intermediate undergoes a synergy ring-opening transition state to form a new intermediate. Afterwards, the new intermediate decomposes into CN by homolysis of the C–C bond.
LanguageEnglish
JournalJournal of the Energy Institute
Early online date5 Jun 2019
DOIs
Publication statusE-pub ahead of print - 5 Jun 2019

Fingerprint

indoles
Density functional theory
pyrolysis
Pyrolysis
density functional theory
Coal
Hydrogen
Nitrogen oxides
coal utilization
nitrogen oxides
rings
Nitrogen
Decomposition
pyrroles
hydrogen
coal
thermal decomposition
decomposition
nitrogen
products

Keywords

  • NOx
  • indole pyrolysis
  • NH3
  • HCN
  • DFT

Cite this

Liu, Ji ; Zhang, Xiaolei ; Hu, Bin ; Lu, Qiang ; Liu, Dingjia ; Dong, Changqing ; Yang, Yongping. / Formation mechanism of HCN and NH3 during indole pyrolysis : a theoretical DFT study. In: Journal of the Energy Institute. 2019.
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abstract = "Coal is a major contributor to the global emission of nitrogen oxides. The NOx formation during coal utilisation typically derives from thermal decomposition of N-containing compounds pyrrole, which usually combines with an aromatic ring in the form of indole. NH3 and HCN are common precursors of NOx from the decomposition of N-containing compounds. In this study, possible pathways of indole pyrolysis to form HCN and NH3 are investigated using the density functional theory (DFT) method. Calculation results indicate that indole pyrolysis has two type of possible initial reactions, which are internal hydrogen transfer and hydrogen homolysis reaction, respectively. The initial reaction mode of indole has a great impact on the subsequent pyrolysis pathway. Additionally, it is shown that indole can produce two nitrogen-containing products, i.e. HCN and NH3. Five pathways will result in the formation of HCN (path-1, path-3, path-a, path-b, path-c), and another two pathways will lead to the NH3 (path-2, path-4). Furthermore, among all the reaction mechanisms of indole pyrolysis, the path-1 is the optimal reaction pathway. During which, indole is converted to a diradical intermediate, then the intermediate undergoes a synergy ring-opening transition state to form a new intermediate. Afterwards, the new intermediate decomposes into CN by homolysis of the C–C bond.",
keywords = "NOx, indole pyrolysis, NH3, HCN, DFT",
author = "Ji Liu and Xiaolei Zhang and Bin Hu and Qiang Lu and Dingjia Liu and Changqing Dong and Yongping Yang",
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Formation mechanism of HCN and NH3 during indole pyrolysis : a theoretical DFT study. / Liu, Ji; Zhang, Xiaolei; Hu, Bin; Lu, Qiang; Liu, Dingjia; Dong, Changqing; Yang, Yongping.

In: Journal of the Energy Institute, 05.06.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Formation mechanism of HCN and NH3 during indole pyrolysis

T2 - Journal of the Energy Institute

AU - Liu, Ji

AU - Zhang, Xiaolei

AU - Hu, Bin

AU - Lu, Qiang

AU - Liu, Dingjia

AU - Dong, Changqing

AU - Yang, Yongping

PY - 2019/6/5

Y1 - 2019/6/5

N2 - Coal is a major contributor to the global emission of nitrogen oxides. The NOx formation during coal utilisation typically derives from thermal decomposition of N-containing compounds pyrrole, which usually combines with an aromatic ring in the form of indole. NH3 and HCN are common precursors of NOx from the decomposition of N-containing compounds. In this study, possible pathways of indole pyrolysis to form HCN and NH3 are investigated using the density functional theory (DFT) method. Calculation results indicate that indole pyrolysis has two type of possible initial reactions, which are internal hydrogen transfer and hydrogen homolysis reaction, respectively. The initial reaction mode of indole has a great impact on the subsequent pyrolysis pathway. Additionally, it is shown that indole can produce two nitrogen-containing products, i.e. HCN and NH3. Five pathways will result in the formation of HCN (path-1, path-3, path-a, path-b, path-c), and another two pathways will lead to the NH3 (path-2, path-4). Furthermore, among all the reaction mechanisms of indole pyrolysis, the path-1 is the optimal reaction pathway. During which, indole is converted to a diradical intermediate, then the intermediate undergoes a synergy ring-opening transition state to form a new intermediate. Afterwards, the new intermediate decomposes into CN by homolysis of the C–C bond.

AB - Coal is a major contributor to the global emission of nitrogen oxides. The NOx formation during coal utilisation typically derives from thermal decomposition of N-containing compounds pyrrole, which usually combines with an aromatic ring in the form of indole. NH3 and HCN are common precursors of NOx from the decomposition of N-containing compounds. In this study, possible pathways of indole pyrolysis to form HCN and NH3 are investigated using the density functional theory (DFT) method. Calculation results indicate that indole pyrolysis has two type of possible initial reactions, which are internal hydrogen transfer and hydrogen homolysis reaction, respectively. The initial reaction mode of indole has a great impact on the subsequent pyrolysis pathway. Additionally, it is shown that indole can produce two nitrogen-containing products, i.e. HCN and NH3. Five pathways will result in the formation of HCN (path-1, path-3, path-a, path-b, path-c), and another two pathways will lead to the NH3 (path-2, path-4). Furthermore, among all the reaction mechanisms of indole pyrolysis, the path-1 is the optimal reaction pathway. During which, indole is converted to a diradical intermediate, then the intermediate undergoes a synergy ring-opening transition state to form a new intermediate. Afterwards, the new intermediate decomposes into CN by homolysis of the C–C bond.

KW - NOx

KW - indole pyrolysis

KW - NH3

KW - HCN

KW - DFT

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