Hugo Cruchade, Francesco Dalena, Eddy Dib, Abdelhafid Aitblal, Diogenes Honorato Piva, Aymeric Magisson, Svetlana Mintova
{"title":"通过受控合成后水热处理阐明 MFI 纳米沸石中的硅醇去除作用","authors":"Hugo Cruchade, Francesco Dalena, Eddy Dib, Abdelhafid Aitblal, Diogenes Honorato Piva, Aymeric Magisson, Svetlana Mintova","doi":"10.1016/j.surfin.2024.105360","DOIUrl":null,"url":null,"abstract":"<div><div>The rational control of silanol groups is still an elusive dream in zeolite synthesis. To enhance our understanding of this phenomenon, we have performed various hydrothermal post-synthesis treatments on nanosized Silicalite-1 using sodium molybdate, sodium chloride, and ultrapure water to evaluate the alteration of silanol content. All treated samples exhibited a phase transition from orthorhombic to monoclinic confirmed by X-ray diffraction (XRD). Fourier-Transform Infrared (FTIR) and solid-state Nuclear Magnetic Resonance (NMR) spectroscopy showed a decrease in the concentration of silanol groups in the post treated samples. The treatment with sodium molybdate leads to the removal of approximately 98% of the silanol groups, while the samples treated with sodium chloride and ultrapure water showed a decrease of 90% and 20% respectively, compared to the parent silicalite-1. Additionally, the results from pyridine adsorption followed by FTIR show that the Parent-Silicalite-1 and the H<sub>2</sub>O-Silicalite-1 samples contain a significant amount of defects, requiring 13.55 and 11.18 μmol, respectively, to saturate all the unsymmetrical bridging sites, while for the sample treated with sodium chloride only 1.07 µmol is needed to saturate all siloxane sites. In contrast, the treatment with sodium molybdate produced a free-defects zeolite. Molybdenum was found to contribute to the removal of both weak and strong hydrogen-bonded silanol groups through its insertion into the zeolite framework, while sodium played a significant role in condensing open bridges within the zeolite framework and removing less weak and strong hydrogen bonded silanol groups. This condensation of silanol groups seems to be facilitated by the polarization of silanol groups in presence of Na<sup>+</sup> promoting the formation of siloxy groups that eventually condense easily with adjacent SiOH groups, liberating water molecules during the activation process of the samples.</div></div>","PeriodicalId":22081,"journal":{"name":"Surfaces and Interfaces","volume":"55 ","pages":"Article 105360"},"PeriodicalIF":5.7000,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Elucidating silanol removal in MFI nanosized zeolites through controlled post-synthesis hydrothermal treatments\",\"authors\":\"Hugo Cruchade, Francesco Dalena, Eddy Dib, Abdelhafid Aitblal, Diogenes Honorato Piva, Aymeric Magisson, Svetlana Mintova\",\"doi\":\"10.1016/j.surfin.2024.105360\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The rational control of silanol groups is still an elusive dream in zeolite synthesis. To enhance our understanding of this phenomenon, we have performed various hydrothermal post-synthesis treatments on nanosized Silicalite-1 using sodium molybdate, sodium chloride, and ultrapure water to evaluate the alteration of silanol content. All treated samples exhibited a phase transition from orthorhombic to monoclinic confirmed by X-ray diffraction (XRD). Fourier-Transform Infrared (FTIR) and solid-state Nuclear Magnetic Resonance (NMR) spectroscopy showed a decrease in the concentration of silanol groups in the post treated samples. The treatment with sodium molybdate leads to the removal of approximately 98% of the silanol groups, while the samples treated with sodium chloride and ultrapure water showed a decrease of 90% and 20% respectively, compared to the parent silicalite-1. Additionally, the results from pyridine adsorption followed by FTIR show that the Parent-Silicalite-1 and the H<sub>2</sub>O-Silicalite-1 samples contain a significant amount of defects, requiring 13.55 and 11.18 μmol, respectively, to saturate all the unsymmetrical bridging sites, while for the sample treated with sodium chloride only 1.07 µmol is needed to saturate all siloxane sites. In contrast, the treatment with sodium molybdate produced a free-defects zeolite. Molybdenum was found to contribute to the removal of both weak and strong hydrogen-bonded silanol groups through its insertion into the zeolite framework, while sodium played a significant role in condensing open bridges within the zeolite framework and removing less weak and strong hydrogen bonded silanol groups. This condensation of silanol groups seems to be facilitated by the polarization of silanol groups in presence of Na<sup>+</sup> promoting the formation of siloxy groups that eventually condense easily with adjacent SiOH groups, liberating water molecules during the activation process of the samples.</div></div>\",\"PeriodicalId\":22081,\"journal\":{\"name\":\"Surfaces and Interfaces\",\"volume\":\"55 \",\"pages\":\"Article 105360\"},\"PeriodicalIF\":5.7000,\"publicationDate\":\"2024-10-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Surfaces and Interfaces\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2468023024015165\",\"RegionNum\":2,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Surfaces and Interfaces","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2468023024015165","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Elucidating silanol removal in MFI nanosized zeolites through controlled post-synthesis hydrothermal treatments
The rational control of silanol groups is still an elusive dream in zeolite synthesis. To enhance our understanding of this phenomenon, we have performed various hydrothermal post-synthesis treatments on nanosized Silicalite-1 using sodium molybdate, sodium chloride, and ultrapure water to evaluate the alteration of silanol content. All treated samples exhibited a phase transition from orthorhombic to monoclinic confirmed by X-ray diffraction (XRD). Fourier-Transform Infrared (FTIR) and solid-state Nuclear Magnetic Resonance (NMR) spectroscopy showed a decrease in the concentration of silanol groups in the post treated samples. The treatment with sodium molybdate leads to the removal of approximately 98% of the silanol groups, while the samples treated with sodium chloride and ultrapure water showed a decrease of 90% and 20% respectively, compared to the parent silicalite-1. Additionally, the results from pyridine adsorption followed by FTIR show that the Parent-Silicalite-1 and the H2O-Silicalite-1 samples contain a significant amount of defects, requiring 13.55 and 11.18 μmol, respectively, to saturate all the unsymmetrical bridging sites, while for the sample treated with sodium chloride only 1.07 µmol is needed to saturate all siloxane sites. In contrast, the treatment with sodium molybdate produced a free-defects zeolite. Molybdenum was found to contribute to the removal of both weak and strong hydrogen-bonded silanol groups through its insertion into the zeolite framework, while sodium played a significant role in condensing open bridges within the zeolite framework and removing less weak and strong hydrogen bonded silanol groups. This condensation of silanol groups seems to be facilitated by the polarization of silanol groups in presence of Na+ promoting the formation of siloxy groups that eventually condense easily with adjacent SiOH groups, liberating water molecules during the activation process of the samples.
期刊介绍:
The aim of the journal is to provide a respectful outlet for ''sound science'' papers in all research areas on surfaces and interfaces. We define sound science papers as papers that describe new and well-executed research, but that do not necessarily provide brand new insights or are merely a description of research results.
Surfaces and Interfaces publishes research papers in all fields of surface science which may not always find the right home on first submission to our Elsevier sister journals (Applied Surface, Surface and Coatings Technology, Thin Solid Films)