The role of H2O in structural nitrogen migration during coal devolatilization under oxy-steam combustion conditions

Yue, Shuang; Wang, Chunbo; Huang, Yangen; Xu, Ziyang; Xing, Jiaying; Anthony, Edward J.

doi:10.1016/j.fuproc.2021.107040

Cited by 20 publications

(3 citation statements)

References 45 publications

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“…This is due to the fact that nascent HCN can be further hydrolyzed to NH 3 with sufficient steam. Regarding the negative impact of steam on the HCN yield, Yue et al also claimed that excessive steam concentration had an inhibiting effect on HCN emission. In addition, HCN-N/NH 3 –N molar ratio exhibits an initial increase followed by a subsequent decrease with the increment of steam content. HCN + H 2 normalO → NH 3 + CO NH i + normalH ↔ NH normali − 1 + H 2 …”

Section: Resultsmentioning

confidence: 99%

Exploring the Green Production of Ammonia from Nitrogen-Enriched Biowaste Gasification: Nitrogen Conversion from Tea Waste and Theanine

Wang,

Xu,

Shen

et al. 2023

Ind. Eng. Chem. Res.

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Section: Resultsmentioning

confidence: 99%

Exploring the Green Production of Ammonia from Nitrogen-Enriched Biowaste Gasification: Nitrogen Conversion from Tea Waste and Theanine

Wang,

Xu,

Shen

et al. 2023

Ind. Eng. Chem. Res.

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“…The nitrogen present in the coal structures is mainly found in the form of organic aromatic heterocycles. Among them, pyrrole with a nitrogenous five-membered ring and pyridine with a nitrogenous six-membered ring exhibit the simplest structures and are commonly used as model compounds for studying the structures of nitrogen-containing molecules. , However, pyrrole and pyridine do not exist independently in coal bodies and are often combined with aromatic rings to form carbazole, indole, and quinoline structures. − Therefore, in this paper, pyrrole, pyridine, indole, quinoline, and carbazole were examined to reveal the effects of nitrogen-containing molecular structures on CSC. The optimized model structure is shown in Figure .…”

Section: Calculation Details and Experimental Sectionmentioning

confidence: 99%

Reaction Mechanism of Nitrogen-Containing Heterocyclic Compounds Affecting Coal Spontaneous Combustion

Zhang,

Xi,

Gong

et al. 2023

ACS Omega

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To uncover the reaction mechanism of nitrogencontaining heterocyclic compounds affecting coal self-heating, quantum chemical calculations and X-ray photoelectron spectroscopy (XPS) experiments were applied to elucidate the reaction pathways and thermodynamic characteristics of pyrrole, pyridine, indole, quinoline, and carbazole. Results show that in pyrrole, pyridine, indole, quinoline, and carbazole, the reaction with O 2 captures the H atom and leads to the formation of •OOH and pyrrolyl, pyridinyl, indolyl, quinolinyl, and carbazolyl radicals, respectively. The activation energies are 118.15, 86.642, 34.132, 21.004, and 47.259 kJ/mol, respectively. ROO• formed by spontaneous adsorption of O 2 by nitrogen-containing radicals undergoes self-reaction, and the O−O bond is broken and dehydrogenated to generate •OH. Subsequently, at room temperature, •OH reacts with pyrrole, pyridine, indole, quinoline, and carbazole, resulting in the formation of H 2 O and pyrrolyl, pyridinyl, indolyl, quinolinyl, and carbazolyl radicals, respectively, thereby forming a cyclic chain reaction. The XPS analysis yielded the following findings: (i) when the temperature rises to 70 °C, the N-5 and N-6 content decrease, which is attributed to the activation energy; (ii) when the temperature reaches 200 °C, the N-5 content decreases, which can be attributed to the activation energy required for the oxidation of pyrrole (118.5 kJ/mol).

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“…Once formed, each NO x molecule involved in the reduction will undergo subsequent reactions by one of two types: (i) homogeneous reaction with reductive radical or gas such as NH i , CH i and CO; (ii) heterogeneous reaction with functional groups over the carbonaceous surface [5]. Up to now, some studies have paid attention to the NO reduction through macroscopic experiments in uidized bed [6], drop-tube furnace [7] and jet stirred reactor [8], as well as microscopic tests including X-ray photoelectron spectroscopy (XPS) [9], Fourier-transform infrared spectroscopy (FTIR) [10] and Raman spectra [11]. A common outcome from these studies is that in oxy-fuel combustion, a large amount of CO can be formed by the interaction of CO 2 with carbonaceous surface, and high levels of CO exert signi cant in uence on NO emissions.…”

Section: Introductionmentioning

confidence: 99%

A new insight on the NO–CO reaction at the electronic level: homogeneous, E-R, and L–H mechanisms

Yue

2022

J Mol Model

Self Cite

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Carbonaceous surface, as one of the major carriers in coal combustion, was found to exert great in uence on nitric oxide with carbon monoxide (NO-CO) reactions. Although there have been some studies addressing the NO-CO reaction, the inherent mechanism still remains obscure. In this work, some updated mechanisms with details were proposed at the electronic level. Using density functional theory (DFT) calculations, the preferred pathways were identi ed with three channels consisting of homogeneous reaction, the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) heterogeneous reactions. Through the analyses of chemical bond and electronic transfer, the reasons for the difference in thermodynamic energy among the three mechanisms were discussed in detail. Results show that among these channels, the NO-CO reaction is more likely to occur along E-R mechanism, due to its lower energy barrier of ratedetermining step. At the initial stage, there is a higher degree of electronic localization between NO molecules in E-R mechanism, leading to a lower energy barrier during the formation of NO dimer. Meanwhile, a large quantify of electrons oods into the N-N, N-O and O-O bonds of NO dimer in the homogeneous reaction, which certainly gets more di cult for the dissociation of O atoms in gas phase. Accordingly, the following stage of N 2 formation has a higher energy barrier than both E-R and L-H mechanisms. Compared to L-H mechanism, the E-R mechanism exhibits a lower degree of electronic localization between N 2 O and carbonaceous surface. Therefore, the interfacial interaction between them in E-R mechanism is weaker than that in L-H mechanism, so that it is easy to take N 2 out of carbonaceous surface in E-R mechanism. To sum up, the result deepens the knowledge about the NO-CO reaction, which will help to further develop the oxy-fuel combustion technology.

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The role of H2O in structural nitrogen migration during coal devolatilization under oxy-steam combustion conditions

Cited by 20 publications

References 45 publications

Exploring the Green Production of Ammonia from Nitrogen-Enriched Biowaste Gasification: Nitrogen Conversion from Tea Waste and Theanine

Exploring the Green Production of Ammonia from Nitrogen-Enriched Biowaste Gasification: Nitrogen Conversion from Tea Waste and Theanine

Reaction Mechanism of Nitrogen-Containing Heterocyclic Compounds Affecting Coal Spontaneous Combustion

A new insight on the NO–CO reaction at the electronic level: homogeneous, E-R, and L–H mechanisms

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