Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction
Silicalite-1 core/Al-ZSM-5 shell zeolite crystals were prepared in various sizes for use as catalysts in methane dehydroaromatization (MDA), and the growth kinetics and corresponding physicochemical properties of this core–shell zeolite were investigated. Al-ZSM-5 was grown on silicalite-1 seeds at...
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MDPI AG
2021-06-01
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| author | Do-Young Hong Hyun Su Kim Haoxiang Zhang Su Kyung Kang Elsa Tsegay Tikue Pyung Soo Lee |
| author_facet | Do-Young Hong Hyun Su Kim Haoxiang Zhang Su Kyung Kang Elsa Tsegay Tikue Pyung Soo Lee |
| author_sort | Do-Young Hong |
| collection | DOAJ |
| description | Silicalite-1 core/Al-ZSM-5 shell zeolite crystals were prepared in various sizes for use as catalysts in methane dehydroaromatization (MDA), and the growth kinetics and corresponding physicochemical properties of this core–shell zeolite were investigated. Al-ZSM-5 was grown on silicalite-1 seeds at various Si/Al ratios. Core–shell catalysts of all size variations exhibited similar deactivation trends in the MDA reaction, with minor changes in aromatic yields despite clear differences in reaction channel lengths and acid-site properties. This outcome was shown to originate from the unique growth kinetics of the Al-ZSM-5 layer on silicalite-1 seeds, in which the Al species in the sol used in the synthesis were consumed quickly during the early aggregative growth period. This led to an interesting spatial distribution of Al in the Al-ZSM-5 layer, in that the inner layer was relatively Al-rich. This distribution is advantageous because it can inhibit coke deactivation, which often occurs at the catalyst surface during MDA. However, a substantial quantity of Si–OH nests, which inhibit the effective loading of Mo species at the acid sites of the crystals, were detected in the microstructural analysis of large crystals. Therefore, this study shows that silicalite-1 core/Al-ZSM-5 shell zeolites can be prepared for use as coke-resistant catalysts for the MDA reaction. Further work is required, however, to design a synthesis method which reduces the number of Si–OH nests formed. |
| first_indexed | 2024-03-10T10:37:19Z |
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| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T10:37:19Z |
| publishDate | 2021-06-01 |
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| series | Crystals |
| spelling | doaj.art-a17bf01889624a39ac6b9f01b32ad3962023-11-21T23:13:05ZengMDPI AGCrystals2073-43522021-06-0111664710.3390/cryst11060647Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization ReactionDo-Young Hong0Hyun Su Kim1Haoxiang Zhang2Su Kyung Kang3Elsa Tsegay Tikue4Pyung Soo Lee5Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology (KRICT), 141, Gajeongro, Daejeon 34114, KoreaDepartment of Chemical Engineering and Material Science, Chung-Ang University, 84, Heukseok-ro, Seoul 06974, KoreaDepartment of Chemical Engineering and Material Science, Chung-Ang University, 84, Heukseok-ro, Seoul 06974, KoreaDepartment of Chemical Engineering and Material Science, Chung-Ang University, 84, Heukseok-ro, Seoul 06974, KoreaDepartment of Intelligent Energy and Industry, Chung-Ang University, 84, Heuksek-ro, Seoul 06974, KoreaDepartment of Chemical Engineering and Material Science, Chung-Ang University, 84, Heukseok-ro, Seoul 06974, KoreaSilicalite-1 core/Al-ZSM-5 shell zeolite crystals were prepared in various sizes for use as catalysts in methane dehydroaromatization (MDA), and the growth kinetics and corresponding physicochemical properties of this core–shell zeolite were investigated. Al-ZSM-5 was grown on silicalite-1 seeds at various Si/Al ratios. Core–shell catalysts of all size variations exhibited similar deactivation trends in the MDA reaction, with minor changes in aromatic yields despite clear differences in reaction channel lengths and acid-site properties. This outcome was shown to originate from the unique growth kinetics of the Al-ZSM-5 layer on silicalite-1 seeds, in which the Al species in the sol used in the synthesis were consumed quickly during the early aggregative growth period. This led to an interesting spatial distribution of Al in the Al-ZSM-5 layer, in that the inner layer was relatively Al-rich. This distribution is advantageous because it can inhibit coke deactivation, which often occurs at the catalyst surface during MDA. However, a substantial quantity of Si–OH nests, which inhibit the effective loading of Mo species at the acid sites of the crystals, were detected in the microstructural analysis of large crystals. Therefore, this study shows that silicalite-1 core/Al-ZSM-5 shell zeolites can be prepared for use as coke-resistant catalysts for the MDA reaction. Further work is required, however, to design a synthesis method which reduces the number of Si–OH nests formed.https://www.mdpi.com/2073-4352/11/6/647Al-ZSM-5silicalite-1core-shellzeoliteacid distribution |
| spellingShingle | Do-Young Hong Hyun Su Kim Haoxiang Zhang Su Kyung Kang Elsa Tsegay Tikue Pyung Soo Lee Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction Crystals Al-ZSM-5 silicalite-1 core-shell zeolite acid distribution |
| title | Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction |
| title_full | Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction |
| title_fullStr | Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction |
| title_full_unstemmed | Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction |
| title_short | Si–OH Nest and Al Distribution of Silicalite-1 Core/Al-ZSM-5 Shell Zeolites for Methane Dehydroaromatization Reaction |
| title_sort | si oh nest and al distribution of silicalite 1 core al zsm 5 shell zeolites for methane dehydroaromatization reaction |
| topic | Al-ZSM-5 silicalite-1 core-shell zeolite acid distribution |
| url | https://www.mdpi.com/2073-4352/11/6/647 |
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