Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study
Silica (SiO<sub>2</sub>), accounting for the main component of fly ash, plays a vital role in the heterogeneous formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) in high-temperature industrial processes. Silica clusters, as the basic units of silica, provide reasonab...
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MDPI AG
2024-03-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/25/6/3485 |
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| author | Fei Xu Xiaotong Wang Ying Li Yongxia Hu Ying Zhou Mohammad Hassan Hadizadeh |
| author_facet | Fei Xu Xiaotong Wang Ying Li Yongxia Hu Ying Zhou Mohammad Hassan Hadizadeh |
| author_sort | Fei Xu |
| collection | DOAJ |
| description | Silica (SiO<sub>2</sub>), accounting for the main component of fly ash, plays a vital role in the heterogeneous formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) in high-temperature industrial processes. Silica clusters, as the basic units of silica, provide reasonable models to understand the general trends of complex surface reactions. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. By employing density functional theory, this study examined the formation of 2-chlorothiophenolate from 2-CTP adsorbed on the dehydrated silica cluster ((SiO<sub>2</sub>)<sub>3</sub>) and the hydroxylated silica cluster ((SiO<sub>2</sub>)<sub>3</sub>O<sub>2</sub>H<sub>4</sub>). Additionally, this study investigated the formation of pre-PCTA/DTs, the crucial intermediates involved in PCTA/DT formation, from the coupling of two adsorbed 2-chlorothiophenolates via the Langmuir–Hinshelwood (L–H) mechanism and the coupling of adsorbed 2-chlorothiophenolate with gas-phase 2-CTP via the Eley–Rideal (E–R) mechanism on silica clusters. Moreover, the rate constants for the main elementary steps were calculated over the temperature range of 600–1200 K. Our study demonstrates that the 2-CTP is more likely to adsorb on the termination of the dehydrated silica cluster, which exhibits more effective catalysis in the formation of 2-chlorothiophenolate compared with the hydroxylated silica cluster. Moreover, the E–R mechanism mainly contributes to the formation of pre-PCTAs, whereas the L–H mechanism is prone to the formation of pre-PCDTs on dehydrated and hydroxylated silica clusters. Silica can act as a relatively mild catalyst in facilitating the heterogeneous formation of pre-PCTA/DTs from 2-CTP. This research provides new insights into the surface-mediated generation of PCTA/DTs, further providing theoretical foundations to reduce dioxin emission and establish dioxin control strategies. |
| first_indexed | 2024-04-24T18:11:18Z |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-04-24T18:11:18Z |
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| spelling | doaj.art-5d649d4ac84945558e01de0f48eb8f932024-03-27T13:46:15ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672024-03-01256348510.3390/ijms25063485Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical StudyFei Xu0Xiaotong Wang1Ying Li2Yongxia Hu3Ying Zhou4Mohammad Hassan Hadizadeh5Environment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaSilica (SiO<sub>2</sub>), accounting for the main component of fly ash, plays a vital role in the heterogeneous formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) in high-temperature industrial processes. Silica clusters, as the basic units of silica, provide reasonable models to understand the general trends of complex surface reactions. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. By employing density functional theory, this study examined the formation of 2-chlorothiophenolate from 2-CTP adsorbed on the dehydrated silica cluster ((SiO<sub>2</sub>)<sub>3</sub>) and the hydroxylated silica cluster ((SiO<sub>2</sub>)<sub>3</sub>O<sub>2</sub>H<sub>4</sub>). Additionally, this study investigated the formation of pre-PCTA/DTs, the crucial intermediates involved in PCTA/DT formation, from the coupling of two adsorbed 2-chlorothiophenolates via the Langmuir–Hinshelwood (L–H) mechanism and the coupling of adsorbed 2-chlorothiophenolate with gas-phase 2-CTP via the Eley–Rideal (E–R) mechanism on silica clusters. Moreover, the rate constants for the main elementary steps were calculated over the temperature range of 600–1200 K. Our study demonstrates that the 2-CTP is more likely to adsorb on the termination of the dehydrated silica cluster, which exhibits more effective catalysis in the formation of 2-chlorothiophenolate compared with the hydroxylated silica cluster. Moreover, the E–R mechanism mainly contributes to the formation of pre-PCTAs, whereas the L–H mechanism is prone to the formation of pre-PCDTs on dehydrated and hydroxylated silica clusters. Silica can act as a relatively mild catalyst in facilitating the heterogeneous formation of pre-PCTA/DTs from 2-CTP. This research provides new insights into the surface-mediated generation of PCTA/DTs, further providing theoretical foundations to reduce dioxin emission and establish dioxin control strategies.https://www.mdpi.com/1422-0067/25/6/34852-chlorothiophenolsilica clusterspre-PCTA/DT formationL–H and E–R mechanismDFT calculations |
| spellingShingle | Fei Xu Xiaotong Wang Ying Li Yongxia Hu Ying Zhou Mohammad Hassan Hadizadeh Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study International Journal of Molecular Sciences 2-chlorothiophenol silica clusters pre-PCTA/DT formation L–H and E–R mechanism DFT calculations |
| title | Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study |
| title_full | Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study |
| title_fullStr | Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study |
| title_full_unstemmed | Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study |
| title_short | Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study |
| title_sort | formation of pre pcta dt intermediates from 2 chlorothiophenol on silica clusters a quantum mechanical study |
| topic | 2-chlorothiophenol silica clusters pre-PCTA/DT formation L–H and E–R mechanism DFT calculations |
| url | https://www.mdpi.com/1422-0067/25/6/3485 |
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