Infrared spectroscopic study of the acid properties of dealuminated BEA zeolites
Saved in:
| Title: | Infrared spectroscopic study of the acid properties of dealuminated BEA zeolites |
|---|---|
| Authors: | Marques, J.P.1, Gener, I.2, Ayrault, P.2, Bordado, J.C.1, Lopes, J.M.1, Ramôa Ribeiro, F.1, Guisnet, M.2 |
| Source: | Microporous & Mesoporous Materials. Jun2003, Vol. 60 Issue 1-3, p251. 12p. |
| Subjects: | Zeolites, Hydrochloric acid |
| Abstract: | A series of HBEA samples were prepared by dealumination through three different methods (steaming, treatments with hydrochloric acid and ammonium hexafluorosilicate (HFS) solutions) of a parent sample with total and framework Si:Al ratios of 12.5 and 33, respectively, constituted of 20 nm crystallites. The samples were characterized by XRD, nitrogen adsorption and pyridine adsorption–desorption followed by IR spectroscopy. Whereas the three dealumination treatments have practically no effect on crystallinity and nitrogen adsorption properties, they cause large changes in the ranges of the O–H bond stretching modes (3300–3800 cm−1) and of the most intense IR absorption of pyridine (1400–1700 cm−1). Treatments with HCl or HFS cause the most significant changes: disappearance of the 3662 and 3782 cm−1 bands corresponding to extraframework Al species and to tricoordinated Al species partially connected to the framework, respectively, appearance of additional bands at 1603 and 1446 cm−1 ascribed to a new type of pyridine species coordinated to Lewis sites (PyL2) and for desorption temperatures above 350 °C, of a band at 1462 cm−1 generally ascribed to iminium ions, apparently at the expense of the PyL2 band. In agreement with this formation of iminium ions, desorption at high temperatures causes the complete disappearance of pyridinium ions without complete restoration of the acidic bridging hydroxyl band. PyL2 species are proposed to be pyridine molecules coordinated to Lewis sites and interacting through hydrogen bond with protonic sites. [Copyright &y& Elsevier] |
| Copyright of Microporous & Mesoporous Materials is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
|---|---|
| Header | DbId: egs DbLabel: Engineering Source An: 9953123 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Infrared spectroscopic study of the acid properties of dealuminated BEA zeolites – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Marques%2C+J%2EP%2E%22">Marques, J.P.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Gener%2C+I%2E%22">Gener, I.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Ayrault%2C+P%2E%22">Ayrault, P.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Bordado%2C+J%2EC%2E%22">Bordado, J.C.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Lopes%2C+J%2EM%2E%22">Lopes, J.M.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Ramôa+Ribeiro%2C+F%2E%22">Ramôa Ribeiro, F.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Guisnet%2C+M%2E%22">Guisnet, M.</searchLink><relatesTo>2</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Microporous+%26+Mesoporous+Materials%22">Microporous & Mesoporous Materials</searchLink>. Jun2003, Vol. 60 Issue 1-3, p251. 12p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Zeolites%22">Zeolites</searchLink><br /><searchLink fieldCode="DE" term="%22Hydrochloric+acid%22">Hydrochloric acid</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: A series of HBEA samples were prepared by dealumination through three different methods (steaming, treatments with hydrochloric acid and ammonium hexafluorosilicate (HFS) solutions) of a parent sample with total and framework Si:Al ratios of 12.5 and 33, respectively, constituted of 20 nm crystallites. The samples were characterized by XRD, nitrogen adsorption and pyridine adsorption–desorption followed by IR spectroscopy. Whereas the three dealumination treatments have practically no effect on crystallinity and nitrogen adsorption properties, they cause large changes in the ranges of the O–H bond stretching modes (3300–3800 cm−1) and of the most intense IR absorption of pyridine (1400–1700 cm−1). Treatments with HCl or HFS cause the most significant changes: disappearance of the 3662 and 3782 cm−1 bands corresponding to extraframework Al species and to tricoordinated Al species partially connected to the framework, respectively, appearance of additional bands at 1603 and 1446 cm−1 ascribed to a new type of pyridine species coordinated to Lewis sites (PyL2) and for desorption temperatures above 350 °C, of a band at 1462 cm−1 generally ascribed to iminium ions, apparently at the expense of the PyL2 band. In agreement with this formation of iminium ions, desorption at high temperatures causes the complete disappearance of pyridinium ions without complete restoration of the acidic bridging hydroxyl band. PyL2 species are proposed to be pyridine molecules coordinated to Lewis sites and interacting through hydrogen bond with protonic sites. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Microporous & Mesoporous Materials is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=9953123 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/S1387-1811(03)00382-2 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 251 Subjects: – SubjectFull: Zeolites Type: general – SubjectFull: Hydrochloric acid Type: general Titles: – TitleFull: Infrared spectroscopic study of the acid properties of dealuminated BEA zeolites Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Marques, J.P. – PersonEntity: Name: NameFull: Gener, I. – PersonEntity: Name: NameFull: Ayrault, P. – PersonEntity: Name: NameFull: Bordado, J.C. – PersonEntity: Name: NameFull: Lopes, J.M. – PersonEntity: Name: NameFull: Ramôa Ribeiro, F. – PersonEntity: Name: NameFull: Guisnet, M. IsPartOfRelationships: – BibEntity: Dates: – D: 19 M: 06 Text: Jun2003 Type: published Y: 2003 Identifiers: – Type: issn-print Value: 13871811 Numbering: – Type: volume Value: 60 – Type: issue Value: 1-3 Titles: – TitleFull: Microporous & Mesoporous Materials Type: main |
| ResultId | 1 |
