Mechanical insight into the formation of H2S from thiophene pyrolysis: The influence of H2O

Liu, Ji; Fan, Xin-rui; Zhao, Wei; Yang, Shuang-wei; Hu, Bin; ShiGuan, Yang; Lü, Qiang

doi:10.1016/j.chemosphere.2021.130628

Cited by 12 publications

(8 citation statements)

References 49 publications

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“…Therefore, the initial step of thiophene pyrolysis is the breakage of the C–S bond. Breaking the C–S bond directly requires lots of energy, while the energy barrier of hydrogen transfer is much lower . The hydrogen transfer between carbon atoms leads to the ring opening of thiophene, and the path is shown in Figure , while the changes of MBO are shown in Figure .…”

Section: Resultsmentioning

confidence: 57%

“…Breaking the C−S bond directly requires lots of energy, while the energy barrier of hydrogen transfer is much lower. 30 The hydrogen transfer between carbon atoms leads to the ring opening of thiophene, and the path is shown in Figure 1, while the changes of MBO are shown in Figure 2. The interaction of C(4)−H( 8) is enhanced while the hydrogen atom transferred from C(3) to C(4), weakening C(3)−C(4) and C(4)−S bonds.…”

Section: Resultsmentioning

confidence: 99%

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Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study

Xian,

Xu,

2023

ACS Omega

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Clean coal technology is the important thrust to the achievement of "carbon neutralization"; clearing the transformation mechanism of thiophene, the dominant organic sulfur species in coal, is conducive to promoting the development of sulfur removal technology. DFT calculations were performed, and 28 reaction paths were proposed in this research, clarifying the decomposition mechanism of thiophene and the fixation mechanism of H 2 S. Thiophene is pyrolyzed mainly through the hydrogentransfer reaction, which occurs at above 2000 K rather than 800 K. The hydrogen transfer between the C−C bond rather than the C−S bond causes the ring opening. Hydrogen promotes the decomposition of thiophene, which happens at 800 K, with a molar ratio of hydrogen to thiophene of 5. Therefore, thiophene is decomposed at 800 K mainly through the hydrogenation reaction that occurs at para carbons and the C−S bond, the H 2 S elimination reaction, and the generation of ethane. Furthermore, H 2 S can be converted into thiophene through the addition reaction with unsaturated hydrocarbon, or the dehydration reaction with hydroxyl or carboxyl groups. The combination between H 2 S and the aliphatic compound occurs at 800 K, which is mainly influenced by the species of the functional group rather than the composition and morphology of the carbon chain. Meanwhile, the conversion of aromatic compounds tends to the generation of aryl mercaptan rather than thiophene at around 800 K.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study

Xian,

Xu,

2023

ACS Omega

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“…Thiophene sulfides are the main solid and liquid intermediates of sulfur during pyrolysis , and have been widely used as model compounds in studies about sulfur migration. Generally, thiophene will also decompose into the gaseous phase in the forms of H 2 S, COS, CS 2 , and SO 2 . ,− Guo et al, Yan et al, and Vasiliou et al studied the fast pyrolysis characteristics of thiophene sulfides in different geometries (thiophene, 2-methyl-thiophene, benzo-thiophene, and dibenzothiophene). The results indicated that, albeit the distinct structure of thiophene-S, H 2 S is the preferred S-containing product, with respect to COS and SO 2 .…”

Section: Introductionmentioning

confidence: 99%

Formation of Sulfur Species from Thiophene Decomposition and the Impact of Alkali Metal Ions: A Density Functional Theory Study

Liu,

Xia,

Sun

et al. 2024

Energy Fuels

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Pyrolysis is an efficient utilization method for Scontaining organic solid wastes to produce value-added chemicals and fuels but is accompanied by gaseous pollutants (e.g., H 2 S and COS). The selective transformation of sulfur to H 2 S in the pyrolysis gas will be beneficial for the quality improvement of liquid and solid products, as well as the further management of sulfur. However, the S-containing gas formation mechanism, especially the influence mechanism of widely presented alkali metals, is still unclear. Herein, the formation pathways of Scontaining radicals/gases (S, SH, CS radicals, and H 2 S) was investigated by combining density functional theory (DFT), kinetic calculations, and wave function analysis with thiophene as the model compound. The impact of K + and Na + on Scontaining species formation was carefully studied to elucidate the enrichment method for H 2 S. Thiophene decomposition is preferentially initialized by the 1,2-hydrogen transfer reaction. The formation competitiveness of S-containing species is in the order SH radical ≈ H 2 S > CS radical ≈ S radical, indicating the dominance of H 2 S compared with those of COS and CS 2 formed through CS radicals. Alkali metal ions can enhance the decomposition of thiophene and are beneficial to the direct formation of H 2 S and S radicals through enhanced hydrogen transfer reactions. An inferior generation path of SH radicals is significantly enhanced, and the CS radical formation is inhibited in the presence of K + and Na + . Consequently, alkali metal ions are conducive to direct and indirect generation and enrichment of H 2 S in the gas phase. The elucidation of the enhanced H 2 S formation method can lay a theoretical basis for the waste-to-value utilization of H 2 S in the pyrolysis gas.

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“…In terms of reaction mechanism research, the density functional theory (DFT) method can accurately calculate the activation energy of the chemical reaction in the pyrolysis process and analyze the reaction kinetics in combination with the corresponding model. 25 Moreover, ab-initio (or first-principles) MD (AIMD) is formulated in which the potential energy surface is generated “on the fly” from the instantaneous ground state of the electrons within DFT. This method can study the dynamic reaction process within a short, sub-nanosecond physical timescale.…”

Section: Introductionmentioning

confidence: 99%

“…However, due to the lack of a set of dedicated ReaxFF parameters for the waste tire system, it is difficult to use this method to effectively study the reaction pathway of specific products. In terms of reaction mechanism research, the density functional theory (DFT) method can accurately calculate the activation energy of the chemical reaction in the pyrolysis process and analyze the reaction kinetics in combination with the corresponding model . Moreover, ab-initio (or first-principles) MD (AIMD) is formulated in which the potential energy surface is generated “on the fly” from the instantaneous ground state of the electrons within DFT.…”

Section: Introductionmentioning

confidence: 99%

Formation Mechanism of Monocyclic Aromatic Hydrocarbons during Pyrolysis of Styrene Butadiene Rubber in Waste Passenger Car Tires

Zheng

Yao

et al. 2022

ACS Omega

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The production of aromatic hydrocarbons from the waste tire pyrolysis attracts more and more attention because of its tremendous potential. Based on styrene-butadiene rubber (SBR), which is the main rubber in the waste passenger car tires, this work studies the temperature influence on primary pyrolysis product distribution by experimental techniques (Py-GC/MS, TG−MS), and then, the formation mechanism of monocyclic aromatic hydrocarbons (MAHs) observed in the experiment was analyzed by first-principles calculations. The experimental results show that the MAHs during the pyrolysis mainly include styrene, toluene, and xylene, and subsequent calculations showed that these compounds were formed through a series of primary and secondary reactions. The formation pathways of these typical MAHs were studied via the reaction energy barrier analysis, respectively. It shows that the MAHs were not only derived from the benzene ring in the SBR chain but also generated from short-chain alkenes through the Diels−Alder reaction. The obtained pyrolysis reaction mechanism provides theoretical guidance for the regulation of the pyrolysis product distribution of MAHs.

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Mechanical insight into the formation of H2S from thiophene pyrolysis: The influence of H2O

Cited by 12 publications

References 49 publications

Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study

Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study

Formation of Sulfur Species from Thiophene Decomposition and the Impact of Alkali Metal Ions: A Density Functional Theory Study

Formation Mechanism of Monocyclic Aromatic Hydrocarbons during Pyrolysis of Styrene Butadiene Rubber in Waste Passenger Car Tires

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Mechanical insight into the formation of H2S from thiophene pyrolysis: The influence of H2O

Cited by 12 publications

References 49 publications

Mechanism Insight into the Conversion between H2S and Thiophene during Coal Pyrolysis: A Theoretical Study

Mechanism Insight into the Conversion between H2S and Thiophene during Coal Pyrolysis: A Theoretical Study

Formation of Sulfur Species from Thiophene Decomposition and the Impact of Alkali Metal Ions: A Density Functional Theory Study

Formation Mechanism of Monocyclic Aromatic Hydrocarbons during Pyrolysis of Styrene Butadiene Rubber in Waste Passenger Car Tires

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Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study

Mechanism Insight into the Conversion between H₂S and Thiophene during Coal Pyrolysis: A Theoretical Study