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Mallette AJ, Shilpa K, Rimer JD. The Current Understanding of Mechanistic Pathways in Zeolite Crystallization. Chem Rev 2024; 124:3416-3493. [PMID: 38484327 DOI: 10.1021/acs.chemrev.3c00801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Zeolite catalysts and adsorbents have been an integral part of many commercial processes and are projected to play a significant role in emerging technologies to address the changing energy and environmental landscapes. The ability to rationally design zeolites with tailored properties relies on a fundamental understanding of crystallization pathways to strategically manipulate processes of nucleation and growth. The complexity of zeolite growth media engenders a diversity of crystallization mechanisms that can manifest at different synthesis stages. In this review, we discuss the current understanding of classical and nonclassical pathways associated with the formation of (alumino)silicate zeolites. We begin with a brief overview of zeolite history and seminal advancements, followed by a comprehensive discussion of different classes of zeolite precursors with respect to their methods of assembly and physicochemical properties. The following two sections provide detailed discussions of nucleation and growth pathways wherein we emphasize general trends and highlight specific observations for select zeolite framework types. We then close with conclusions and future outlook to summarize key hypotheses, current knowledge gaps, and potential opportunities to guide zeolite synthesis toward a more exact science.
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Affiliation(s)
- Adam J Mallette
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Kumari Shilpa
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Jeffrey D Rimer
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
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2
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Pan E, Kwon S, Jensen Z, Xie M, Gómez-Bombarelli R, Moliner M, Román-Leshkov Y, Olivetti E. ZeoSyn: A Comprehensive Zeolite Synthesis Dataset Enabling Machine-Learning Rationalization of Hydrothermal Parameters. ACS CENTRAL SCIENCE 2024; 10:729-743. [PMID: 38559304 PMCID: PMC10979502 DOI: 10.1021/acscentsci.3c01615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/14/2024] [Accepted: 02/16/2024] [Indexed: 04/04/2024]
Abstract
Zeolites, nanoporous aluminosilicates with well-defined porous structures, are versatile materials with applications in catalysis, gas separation, and ion exchange. Hydrothermal synthesis is widely used for zeolite production, offering control over composition, crystallinity, and pore size. However, the intricate interplay of synthesis parameters necessitates a comprehensive understanding of synthesis-structure relationships to optimize the synthesis process. Hitherto, public zeolite synthesis databases only contain a subset of parameters and are small in scale, comprising up to a few thousand synthesis routes. We present ZeoSyn, a dataset of 23,961 zeolite hydrothermal synthesis routes, encompassing 233 zeolite topologies and 921 organic structure-directing agents (OSDAs). Each synthesis route comprises comprehensive synthesis parameters: 1) gel composition, 2) reaction conditions, 3) OSDAs, and 4) zeolite products. Using ZeoSyn, we develop a machine learning classifier to predict the resultant zeolite given a synthesis route with >70% accuracy. We employ SHapley Additive exPlanations (SHAP) to uncover key synthesis parameters for >200 zeolite frameworks. We introduce an aggregation approach to extend SHAP to all building units. We demonstrate applications of this approach to phase-selective and intergrowth synthesis. This comprehensive analysis illuminates the synthesis parameters pivotal in driving zeolite crystallization, offering the potential to guide the synthesis of desired zeolites. The dataset is available at https://github.com/eltonpan/zeosyn_dataset.
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Affiliation(s)
- Elton Pan
- Department
of Materials Science and Engineering, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Soonhyoung Kwon
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Zach Jensen
- Department
of Materials Science and Engineering, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mingrou Xie
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Rafael Gómez-Bombarelli
- Department
of Materials Science and Engineering, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Manuel Moliner
- Instituto
de Tecnología Química, Universitat Politècnica de València-Consejo Superior
de Investigaciones Científicas 46022, Valencia, Spain
| | - Yuriy Román-Leshkov
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Elsa Olivetti
- Department
of Materials Science and Engineering, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139, United States
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Mallette AJ, Espindola G, Varghese N, Rimer JD. Highly efficient synthesis of zeolite chabazite using cooperative hydration-mismatched inorganic structure-directing agents. Chem Sci 2024; 15:573-583. [PMID: 38179517 PMCID: PMC10763616 DOI: 10.1039/d3sc05625b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 11/26/2023] [Indexed: 01/06/2024] Open
Abstract
Chabazite (CHA type) zeolite is notoriously difficult to synthesize in the absence of organic structure-directing agents owing to long synthesis times and/or impurity formation. The ability to tailor organic-free syntheses of zeolites is additionally challenging due to the lack of molecular level understanding of zeolite nucleation and growth pathways, particularly the role of inorganic cations. In this study, we reveal that zeolite CHA can be synthesized using six different combinations of inorganic cations, including the first reported seed- and organic-free synthesis without the presence of potassium. We show that lithium, when present in small quantities, is an effective accelerant of CHA crystallization; and that ion pairings can markedly reduce synthesis times and temperatures, while expanding the design space of zeolite CHA formation in comparison to conventional methods utilizing potassium as the sole structure-directing agent. Herein, we posit the effects of cation pairings on zeolite CHA crystallization are related to their hydrated ionic radii. We also emphasize the broader implications for considering the solvated structure and cooperative role of inorganic cations in zeolite synthesis within the context of the reported findings for chabazite.
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Affiliation(s)
- Adam J Mallette
- Department of Chemical and Biomolecular Engineering, University of Houston 4226 Martin Luther King Boulevard Houston TX 77204 USA
| | - Gabriel Espindola
- Department of Chemical and Biomolecular Engineering, University of Houston 4226 Martin Luther King Boulevard Houston TX 77204 USA
| | - Nathan Varghese
- Department of Chemical and Biomolecular Engineering, University of Houston 4226 Martin Luther King Boulevard Houston TX 77204 USA
| | - Jeffrey D Rimer
- Department of Chemical and Biomolecular Engineering, University of Houston 4226 Martin Luther King Boulevard Houston TX 77204 USA
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Asselman K, Kirschhock C, Breynaert E. Illuminating the Black Box: A Perspective on Zeolite Crystallization in Inorganic Media. Acc Chem Res 2023; 56:2391-2402. [PMID: 37566703 PMCID: PMC10515482 DOI: 10.1021/acs.accounts.3c00269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Indexed: 08/13/2023]
Abstract
ConspectusSince the discovery of synthetic zeolites in the 1940s and their implementation in major industrial processes involving adsorption, catalytic conversion, and ion exchange, material scientists have targeted the rational design of zeolites: controlling synthesis to crystallize zeolites with predetermined properties. Decades later, the fundamentals of zeolite synthesis remain largely obscured in a black box, rendering rational design elusive. A major prerequisite to rational zeolite design is to fully understand, and control, the elementary processes governing zeolite nucleation, growth, and stability. The molecular-level investigation of these processes has been severely hindered by the complex multiphasic media in which aluminosilicate zeolites are typically synthesized. This Account documents our recent progress in crystallizing zeolites from synthesis media based on hydrated silicate ionic liquids (HSIL), a synthesis approach facilitating the evaluation of the individual impacts of synthesis parameters such as cation type, water content, and alkalinity on zeolite nucleation, growth, and phase selection. HSIL-based synthesis allows straightforward elucidation of the relationship between the characteristics of the synthesis medium and the properties and structure of the crystalline product. This assists in deriving new insights in zeolite crystallization in an inorganic aluminosilicate system, thus improving the conceptual understanding of nucleation and growth in the context of inorganic zeolite synthesis in general. This Account describes in detail what hydrated silicate ionic liquids are, how they form, and how they assist in improving our understanding of zeolite genesis on a molecular level. It describes the development of ternary phase diagrams for inorganic aluminosilicate zeolites via a systematic screening of synthesis compositions. By evaluating obtained crystal structure properties such as framework composition, topology, and extraframework cation distributions, critical questions are dealt with: Which synthesis variables govern the aluminum content of crystallizing zeolites? How does the aluminum content in the framework determine the expression of different topologies? The crucial role of the alkali cation, taking center stage in all aspects of crystallization, phase selection, and, by extension, transformation is also discussed. New criteria and models for phase selection are proposed, assisting in overcoming the need for excessive trial and error in the development of future synthesis protocols.Recent progress in the development of a toolbox enabling liquid-state characterization of these precursor media has been outlined, setting the stage for the routine monitoring of zeolite crystallization in real time. Current endeavors on and future needs for the in situ investigation of zeolite crystallization are highlighted. Finally, experimentally accessible parameters providing opportunities for modeling zeolite nucleation and growth are identified. Overall, this work provides a perspective toward future developments, identifying research areas ripe for investigation and discovery.
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Affiliation(s)
- Karel Asselman
- Center
for Surface Chemistry and Catalysis − Characterization and
Application Team (COK-KAT), KU Leuven, 3001 Leuven, Belgium
| | - Christine Kirschhock
- Center
for Surface Chemistry and Catalysis − Characterization and
Application Team (COK-KAT), KU Leuven, 3001 Leuven, Belgium
| | - Eric Breynaert
- Center
for Surface Chemistry and Catalysis − Characterization and
Application Team (COK-KAT), KU Leuven, 3001 Leuven, Belgium
- NMR/X-ray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
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Asselman K, Haouas M, Houlleberghs M, Radhakrishnan S, Wangermez W, Kirschhock CEA, Breynaert E. Does Water Enable Porosity in Aluminosilicate Zeolites? Porous Frameworks versus Dense Minerals. CRYSTAL GROWTH & DESIGN 2023; 23:3338-3348. [PMID: 37159660 PMCID: PMC10161221 DOI: 10.1021/acs.cgd.2c01476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 03/14/2023] [Indexed: 05/11/2023]
Abstract
Recently identified zeolite precursors consisting of concentrated, hyposolvated homogeneous alkalisilicate liquids, hydrated silicate ionic liquids (HSIL), minimize correlation of synthesis variables and enable one to isolate and examine the impact of complex parameters such as water content on zeolite crystallization. HSIL are highly concentrated, homogeneous liquids containing water as a reactant rather than bulk solvent. This simplifies elucidation of the role of water during zeolite synthesis. Hydrothermal treatment at 170 °C of Al-doped potassium HSIL with chemical composition 0.5SiO2:1KOH:xH2O:0.013Al2O3 yields porous merlinoite (MER) zeolite when H2O/KOH exceeds 4 and dense, anhydrous megakalsilite when H2O/KOH is lower. Solid phase products and precursor liquids were fully characterized using XRD, SEM, NMR, TGA, and ICP analysis. Phase selectivity is discussed in terms of cation hydration as the mechanism, allowing a spatial cation arrangement enabling the formation of pores. Under water deficient conditions, the entropic penalty of cation hydration in the solid is large and cations need to be entirely coordinated by framework oxygens, leading to dense, anhydrous networks. Hence, the water activity in the synthesis medium and the affinity of a cation to either coordinate to water or to aluminosilicate decides whether a porous, hydrated, or a dense, anhydrous framework is formed.
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Affiliation(s)
- Karel Asselman
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
| | - Mohamed Haouas
- Institut
Lavoisier de Versailles, Université
Paris-Saclay, UVSQ, CNRS, 78000 Versailles, France
| | - Maarten Houlleberghs
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
| | - Sambhu Radhakrishnan
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
- NMRCoRe-NMR-X-Ray
platform for Convergence Research, KU Leuven, Leuven 3001, Belgium
| | - Wauter Wangermez
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
| | - Christine E. A. Kirschhock
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
| | - Eric Breynaert
- Centre
for Surface Chemistry and Catalysis-Characterisation and Application
Team (COK-KAT), KU Leuven, Leuven 3001, Belgium
- NMRCoRe-NMR-X-Ray
platform for Convergence Research, KU Leuven, Leuven 3001, Belgium
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