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Gao Z, Márquez-Álvarez C, Balestra SRG, Yu H, Villaescusa LA, Camblor MA. Mechanism of the Low-Temperature Organic Removal from Imidazolium-Containing Zeolites by Ozone Treatment: Fluoride Retention in Double-4-Rings. Inorg Chem 2024; 63:9953-9966. [PMID: 38757795 PMCID: PMC11134512 DOI: 10.1021/acs.inorgchem.4c01021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/18/2024] [Accepted: 05/08/2024] [Indexed: 05/18/2024]
Abstract
For zeolites synthesized using imidazolium cations, the organic matter can be extracted at very low temperatures (100 °C) using ozone. This is possible for zeolites with 12-ring or larger pores but requires higher temperatures in medium-pore zeolites. The first chemical events in this process occur fast, even at room temperature, and imply the loss of aromaticity likely by the formation of an adduct between ozone and the imidazole ring through carbons C4 and C5. Subsequent rupture of the imidazole ring provides smaller and more flexible fragments that can desorb more readily. This process has been studied experimentally, mainly through infrared spectroscopy, and theoretically by density functional theory. Amazingly, fluoride anions occluded in the small double-four-ring units (d4r) during the synthesis remain inside the cage throughout the whole process when the temperature is not too high (≤150 °C). However, fluoride in larger cages in MFI ends up bonded to silicon in penta or hexacoordinated units, likely out of the cages, after ozone treatment at 150 °C. For several germanosilicate zeolites, the process allows their subsequent degermanation to yield stable high-silica zeolites. Quaternary ammonium cations require harsher conditions that eventually also extract fluoride from zeolite cages, including the d4r unit.
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Affiliation(s)
- Zihao
Rei Gao
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, c/Sor Juana Inés de la Cruz
3, 28049 Madrid, Spain
| | - Carlos Márquez-Álvarez
- Instituto
de Catálisis y Petroleoquímica (ICP), CSIC, c/Marie Curie 2, 28049 Madrid, Spain
| | - Salvador R. G. Balestra
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, c/Sor Juana Inés de la Cruz
3, 28049 Madrid, Spain
- Centro
de Nanociencia y Tecnologías Sostenibles (CNATS), Departamento
de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Ctra. Utrera Km 1, ES-41013 Seville, Spain
| | - Huajian Yu
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, c/Sor Juana Inés de la Cruz
3, 28049 Madrid, Spain
| | - Luis A. Villaescusa
- Instituto
Interuniversitario de Investigación de Reconocimiento Molecular
y Desarrollo Tecnológico (IDM) Universitat de València−Universitat
Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain
- CIBER
de Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid, Spain
- Departamento
de Química, Universitat Politècnica
de València, Camí
de Vera s/n, 46022 Valencia, Spain
| | - Miguel A. Camblor
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, c/Sor Juana Inés de la Cruz
3, 28049 Madrid, Spain
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Peng M, Zhao Y, Xu H, Jiang J, Wu P. Double Four Ring Units-Containing Zeolites: Synthesis, Structural Modification and Catalytic Applications. Chemistry 2023:e202303657. [PMID: 38116930 DOI: 10.1002/chem.202303657] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 12/21/2023]
Abstract
In zeolite frameworks, double four-ring (d4r) configurations are among the most frequent composite building units. The composition variations in d4r units greatly influence the energy and structural modifiability of the zeolitic framework. The introduction of germanium, with a larger ionic radius than silicon or aluminum, not only reduces the energy constraints of d4r in the nucleation and crystal growth of zeolites, but also opens a new window for constructing novel crystalline structures, especially with large or extra-large pores and channels. Ge-enriched d4r units endow germanosilicates with structure diversity readily for post treatments. Promising catalytic materials have been gradually developed and increasingly studied by direct synthesis or post-synthetic isomorphous substitution for Ge. This review focuses on the recent progress in the synthesis, modification, and catalytic application of d4r-containing zeolites, including germanosilicates, aluminosilicates, and silicates.
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Affiliation(s)
- Mingming Peng
- State Key Laboratory of Molecular & Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan
| | - Yuhong Zhao
- State Key Laboratory of Molecular & Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China
| | - Hao Xu
- State Key Laboratory of Molecular & Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China
- Institute of Eco-Chongming, Shanghai, 202162, China
| | - Jingang Jiang
- State Key Laboratory of Molecular & Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China
| | - Peng Wu
- State Key Laboratory of Molecular & Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China
- Institute of Eco-Chongming, Shanghai, 202162, China
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Kemp KC, Mayoral A, Hong SB. Unveiling the Structural Characteristics of Intergrowth Zeolites Synthesized in the Presence of Isopropylimidazolium-Based Cations and Fluoride Anions. J Am Chem Soc 2023; 145:23300-23307. [PMID: 37831968 DOI: 10.1021/jacs.3c08700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Here, we present the synthesis of RTH/ITE and MEL/MFI intergrowth zeolites using 2-isopropylimidazolium-based cations as organic structure-directing agents (OSDAs) in concentrated fluoride media and their local structural properties. Phase selectivity in the synthesis of zeolite intergrowths was found to differ according to the concentration of OSDA cations and fluoride anions in the synthesis mixture as well as to the type of OSDA employed. Molecular modeling results suggest that the crystallization of intergrowth zeolites in fluoride media may be kinetically rather than thermodynamically controlled, as in ordered zeolites. Cs-corrected STEM analysis of MEL/MFI crystals synthesized at HF/OSDA = 2.0 in the presence of 2-isopropyl-1,3-dipropylimidazolium ions as an OSDA indicates the existence of previously unobserved MEL-MFI intergrowth along the [100] direction, leading to a partial blockage of MEL 10-ring channels.
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Affiliation(s)
- Kingsley Christian Kemp
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
| | - Alvaro Mayoral
- Instituto de Nanociencia y Materiales de Aragon (INMA), Spanish National Research Council (CSIC), Universidad de Zaragoza, 12, Calle de Pedro Cerbuna, 50009 Zaragoza, Spain
| | - Suk Bong Hong
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
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