A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors
The pyrolysis of siloxane precursors, such as tetraethoxysilane (TEOS), is commonly employed in the flame synthesis and chemical vapor deposition of silica nanoparticles. In this work, the flow reactor pyrolysis of TEOS is studied using gas chromatography (GC) and synchrotron vacuum ultraviolet phot...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2024-06-01
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| Series: | Applications in Energy and Combustion Science |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666352X24000207 |
| _version_ | 1797213329976983552 |
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| author | Qilong Fang Jun Fang Tianyou Lian Long Zhao Wei Li Yuyang Li |
| author_facet | Qilong Fang Jun Fang Tianyou Lian Long Zhao Wei Li Yuyang Li |
| author_sort | Qilong Fang |
| collection | DOAJ |
| description | The pyrolysis of siloxane precursors, such as tetraethoxysilane (TEOS), is commonly employed in the flame synthesis and chemical vapor deposition of silica nanoparticles. In this work, the flow reactor pyrolysis of TEOS is studied using gas chromatography (GC) and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), and the congener substitution effects from the central C atom to the central Si atom are investigated through comparison with its hydrocarbon counterpart tetraethoxymethane (TEOM). Pyrolysis models of TEOS and TEOM are constructed and validated against the measured results. Modeling analysis, including rate of production analysis and sensitivity analysis, provides insights into chemistry in fuel consumption and product formation. In contrast, the observations of silicon-containing products in SVUV-PIMS experiments provide evidence for crucial decomposition pathways of TEOS. It is observed that TEOS exhibits significantly higher stability than TEOM under pyrolysis conditions. The most abundant products in the pyrolysis of TEOS and TEOM are ethylene and ethanol, and TEOS produces more hydrocarbon products than TEOM. The lower pyrolysis reactivity of TEOS is attributed to the slower unimolecular decomposition reaction which dominates the decomposition of TEOS than TEOM. This can be explained by the hindrance of the extremely strong Si-O bond resulting from the significantly different electronegativity between Si and O. The higher initial decomposition temperature of TEOS enhances the contribution of other decomposition channels, such as C-C bond dissociation and H-abstraction reactions, in TEOS consumption. This leads to the abundant formation of hydrocarbon productions such as methane, ethane, and acetaldehyde. As the main pyrolysis product, the ethanol produced by TEOM pyrolysis is four times that of TEOS due to the congener substitution effects. The ethanol formation pathway in TEOS pyrolysis is different from that in TEOM pyrolysis, which is mainly formed via a newly proposed multi-step mechanism, resulting in a lower yield in TEOS pyrolysis. |
| first_indexed | 2024-04-24T10:56:33Z |
| format | Article |
| id | doaj.art-9c473fab497a40a5b8074470dbddb38e |
| institution | Directory Open Access Journal |
| issn | 2666-352X |
| language | English |
| last_indexed | 2024-04-24T10:56:33Z |
| publishDate | 2024-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Applications in Energy and Combustion Science |
| spelling | doaj.art-9c473fab497a40a5b8074470dbddb38e2024-04-12T04:46:03ZengElsevierApplications in Energy and Combustion Science2666-352X2024-06-0118100265A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursorsQilong Fang0Jun Fang1Tianyou Lian2Long Zhao3Wei Li4Yuyang Li5Institute of Aerospace Propulsion, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR ChinaInstitute of Aerospace Propulsion, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR ChinaInstitute of Aerospace Propulsion, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR ChinaNational Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR ChinaInstitute of Aerospace Propulsion, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR ChinaInstitute of Aerospace Propulsion, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China; Corresponding author.The pyrolysis of siloxane precursors, such as tetraethoxysilane (TEOS), is commonly employed in the flame synthesis and chemical vapor deposition of silica nanoparticles. In this work, the flow reactor pyrolysis of TEOS is studied using gas chromatography (GC) and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), and the congener substitution effects from the central C atom to the central Si atom are investigated through comparison with its hydrocarbon counterpart tetraethoxymethane (TEOM). Pyrolysis models of TEOS and TEOM are constructed and validated against the measured results. Modeling analysis, including rate of production analysis and sensitivity analysis, provides insights into chemistry in fuel consumption and product formation. In contrast, the observations of silicon-containing products in SVUV-PIMS experiments provide evidence for crucial decomposition pathways of TEOS. It is observed that TEOS exhibits significantly higher stability than TEOM under pyrolysis conditions. The most abundant products in the pyrolysis of TEOS and TEOM are ethylene and ethanol, and TEOS produces more hydrocarbon products than TEOM. The lower pyrolysis reactivity of TEOS is attributed to the slower unimolecular decomposition reaction which dominates the decomposition of TEOS than TEOM. This can be explained by the hindrance of the extremely strong Si-O bond resulting from the significantly different electronegativity between Si and O. The higher initial decomposition temperature of TEOS enhances the contribution of other decomposition channels, such as C-C bond dissociation and H-abstraction reactions, in TEOS consumption. This leads to the abundant formation of hydrocarbon productions such as methane, ethane, and acetaldehyde. As the main pyrolysis product, the ethanol produced by TEOM pyrolysis is four times that of TEOS due to the congener substitution effects. The ethanol formation pathway in TEOS pyrolysis is different from that in TEOM pyrolysis, which is mainly formed via a newly proposed multi-step mechanism, resulting in a lower yield in TEOS pyrolysis.http://www.sciencedirect.com/science/article/pii/S2666352X24000207TetraethoxysilaneFlow reactor pyrolysisSVUV-PIMSKinetic modelingCongener substitution effects |
| spellingShingle | Qilong Fang Jun Fang Tianyou Lian Long Zhao Wei Li Yuyang Li A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors Applications in Energy and Combustion Science Tetraethoxysilane Flow reactor pyrolysis SVUV-PIMS Kinetic modeling Congener substitution effects |
| title | A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| title_full | A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| title_fullStr | A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| title_full_unstemmed | A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| title_short | A comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane: Insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| title_sort | comparative pyrolysis study of tetraethoxysilane and tetraethoxymethane insight into congener substitution effects on pyrolysis chemistry of siloxane flame synthesis precursors |
| topic | Tetraethoxysilane Flow reactor pyrolysis SVUV-PIMS Kinetic modeling Congener substitution effects |
| url | http://www.sciencedirect.com/science/article/pii/S2666352X24000207 |
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