Tunable CHA/AEI Zeolite Intergrowths with A Priori Biselective Organic Structure‐Directing Agents: Controlling Enrichment and Implications for Selective Catalytic Reduction of NOx

Bello-Jurado, Estefanía; Schwalbe-Koda, Daniel; Nero, Mathias; Paris, Cecilia; Uusimäki, Toni; Román‐Leshkov, Yuriy; Corma, Avelino; Willhammar, Tom; Gómez‐Bombarelli, Rafael; Moliner, Manuel

doi:10.1002/anie.202201837

Cited by 25 publications

(33 citation statements)

References 31 publications

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“…To date, controlling the intergrowth rate in zeolites has been commonly achieved using a mixture of two OSDAs in various proportions ( e . g ., MFI/MEL and FAU/EMT), changing the water content in synthesis mixtures and the crystallization temperature (STF/SFF and MFI/IDM-1), ,− or by modifying the size/shape of a particular biselective OSDA (CHA/AEI) . To date, however, there are no reports regarding the crystallization time dependence of the intergrowth rate in zeolites as observed here.…”

Section: Resultsmentioning

confidence: 68%

Synthesis and Crystal Growth Mechanism of PST-2: An Aluminosilicate SBS/SBT Zeolite Intergrowth

et al. 2022

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The synthesis of PST-2, an aluminosilicate zeolite intergrowth of cage-based, large-pore SBS and SBT topologies, and its intergrowth characteristics are presented. With the Si/Al ratio and crystallization inorganic structure-directing agent in zeolite synthesis mixtures fixed to 8.0 and Cs + ions, respectively, pure PST-2 is obtained at 120 °C using tetraalkylammonium ions with C/N + ratios of 5−9 as a charge density mismatch (CDM) organic structure-directing agent (OSDA). More interestingly, the intergrowth ratio between SBS and SBT in PST-2 was found to vary notably not only with the type of CDM OSDA employed but also with the crystallization time, unlike the case of other well-known zeolite intergrowths such as β and MFI/MEL. When tetraethylammonium ions are used as a CDM OSDA at 100 °C in the presence of Cs + , the SBS portion in PST-2 decreases from over 60% to less than 45% with increasing crystallization time from 2.5 to 14 days, suggesting that SBS formation is kinetically more favorable than SBT formation. A thorough characterization of changes in the crystallite dimension of PST-2 with crystallization time, together with those in the chemical composition, allowed us to propose a plausible crystal growth mechanism of this large-pore zeolite intergrowth.

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Section: Resultsmentioning

confidence: 68%

Synthesis and Crystal Growth Mechanism of PST-2: An Aluminosilicate SBS/SBT Zeolite Intergrowth

et al. 2022

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“…The AEI/CHA intergrowth framework of the silica-alumina-phosphate zeolite (SAPO-18/34) has been discovered and extensively studied. However, its silica-aluminate form was not synthesized until the combined use of atomic simulation, data mining and human-computer interaction techniques by Manuel Moliner’s group. , They designed individual OSDAs using computer priori techniques to obtain low-cost and highly hydrothermally stable AEI/CHA aluminosilicates, which significantly reducing the complexity and cost of the experiments. The spatial shape and binding energy of different OSDAs with each zeolite were calculated by high-throughput simulations to achieve phase competition equilibrium and control access to the structural motifs in the framework of interest.…”

Section: Synthesis Of Intergrowth Zeolitesmentioning

confidence: 99%

“…Finally, as a promising solution for the future, the competitive growth relationship between the phases of the zeolite would be favorable to clarify by theoretically calculating the interaction energy of the structural OSDA with the zeolite framework structure . This strategy not only provides evidence that the target zeolite can be synthesized with given templating agents, but also allows prediction of the possible phase ratios of the zeolite products based on the calculated binding energies (taking care not to differ too much, otherwise it will lead to single phase zeolites). , …”

Section: Synthesis Of Intergrowth Zeolitesmentioning

confidence: 99%

Intergrowth Zeolites, Synthesis, Characterization, and Catalysis

Wang,

Tong,

Liu

et al. 2023

Chem. Rev.

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Microporous zeolites that can act as heterogeneous catalysts have continued to attract a great deal of academic and industrial interest, but current progress in their synthesis and application is restricted to single-phase zeolites, severely underestimating the potential of intergrowth frameworks. Compared with single-phase zeolites, intergrowth zeolites possess unique properties, such as different diffusion pathways and molecular confinement, or special crystalline pore environments for binding metal active sites. This review first focuses on the structural features and synthetic details of all the intergrowth zeolites, especially providing some insightful discussion of several potential frameworks. Subsequently, characterization methods for intergrowth zeolites are introduced, and highlighting fundamental features of these crystals. Then, the applications of intergrowth zeolites in several of the most active areas of catalysis are presented, including selective catalytic reduction of NOx by ammonia (NH 3 -SCR), methanol to olefins (MTO), petrochemicals and refining, fine chemicals production, and biomass conversion on Beta, and the relationship between structure and catalytic activity was profiled from the perspective of intergrowth grain boundary structure. Finally, the synthesis, characterization, and catalysis of intergrowth zeolites are summarized in a comprehensive discussion, and a brief outlook on the current challenges and future directions of intergrowth zeolites is indicated.

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“…In this way, they can avoid changing or damaging the intrinsic structure of the sample by reducing the electron beam current. Among all, iDPC-STEM has been successfully applied to the atomic-level local structure resolution of a series of important beam-sensitive porous materials, such as zeolites, − MOFs, − COFs, , etc.…”

Section: Introductionmentioning

confidence: 99%

Atomic Imaging of Zeolites and Confined Single Molecules by iDPC-STEM

Xiong,

Wang,

Chen

et al. 2023

ACS Catal.

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Zeolites are a family of nanoporous crystalline materials with ordered channel systems, flexibly adjustable activity, and high hydrothermal stability and have been widely used as adsorbents and catalysts. The micropores of zeolites are comparable to the size of single molecules, which can function as "molecular sieves" by selectively adsorbing or transforming targeted guest molecules. Therefore, a slight mismatch in the dimensions of the pore architecture and guest molecules sometimes will cause thousands of times of changes in the physicochemical processes inside zeolite channels. Adjusting the pore structures to match targeted molecules to precisely regulate the host−guest interactions between them and thereby control the diffusion or reaction pathways has always been one of the most essential principles for designing novel zeolite materials and applications. Thus, it is highly desirable to understand the moving and transforming behaviors of different small molecules in zeolitic nanopores and probe the intricate interactions between them in such delicate situations. The recently emerged integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) holds great potential for imaging zeolite materials at an atomic resolution, since it can greatly improve electron utilization efficiency to reduce the required electron dose and is conducive to light element imaging. This Perspective focuses on the in situ observation of single-molecule adsorption−desorption behaviors in zeolites using the in situ iDPC-STEM imaging technique. We demonstrated that iDPC-STEM is an effective method for probing atomic structures of beam-sensitive zeolite materials and exhibits a remarkable ability in imaging light elements under low-dose conditions. Subsequently, we introduce a general "confined freezing" strategy to immobilize small molecules in size-matchable nanopores, which are stable enough for atomically resolved single-molecule imaging. Finally, three industrially important aromatic molecules with slight differences, including benzene, p-xylene, and pyridine, were selected to demonstrate the different adsorption/desorption behaviors and corresponding host−guest interactions at the subnanometer scale. In this way, we provide a real-space methodology to actually "see" the movement and transformation of individual molecules at the atomic scale and pave the way for clarifying the key role of host−guest interactions in molecular adsorption, diffusion, and reaction processes.

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Tunable CHA/AEI Zeolite Intergrowths with A Priori Biselective Organic Structure‐Directing Agents: Controlling Enrichment and Implications for Selective Catalytic Reduction of NOx

Cited by 25 publications

References 31 publications

Synthesis and Crystal Growth Mechanism of PST-2: An Aluminosilicate SBS/SBT Zeolite Intergrowth

Synthesis and Crystal Growth Mechanism of PST-2: An Aluminosilicate SBS/SBT Zeolite Intergrowth

Intergrowth Zeolites, Synthesis, Characterization, and Catalysis

Atomic Imaging of Zeolites and Confined Single Molecules by iDPC-STEM

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