An environment-friendly and acid-degradable polymer templated synthesis of single-crystal hierarchical zeolites

Hu, Y.; Yue, Yuanyuan; Wang, Chan; Zhu, Haibo; Oyama, S. Ted; Bao, Xiaojun

doi:10.1039/d2ta02198f

Cited by 9 publications

(2 citation statements)

References 54 publications

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“…Taking their unique pore structure and acid properties into account, silicoaluminophosphate SAPO-34 zeolite with the characteristics of the triclinic chabazite (CHA) structure (9.4 Å in diameter) and a small eight-membered ring window (3.8 × 3.8 Å) has been demonstrated to be the best commercial catalyst, which affords exceptional catalytic behaviors, such as high methanol conversion and light olefins selectivity . Nevertheless, the adverse effect is that this material more rapidly loses its catalytic activity caused by bulky hydrocarbon coke depositions, resulting in the diffusion of reactants and products to and from the active centers in the confined microporous channels (∼0.38 nm) being seriously hampered. , In view of this, scores of efforts have been made to optimize the SAPO-34 catalyst so as to alleviate the steric hindrance and improve the diffusional properties. , To date, many strategies, which are mainly grouped into constructive synthesis strategies by utilizing multifunctional soft/hard templates − and destructive synthesis ones via dealumination and desilication, − have been dedicated to fabricating such hierarchical structures with at least two levels of porosity. Despite these elegant achievements, the aforementioned approaches are relatively tedious and cumbersome, with multiple synthesis procedures often involved.…”

Section: Introductionmentioning

confidence: 99%

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Wang,

Dai,

Dai

et al. 2024

ACS Appl. Mater. Interfaces

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It is well known that low-silica SAPO-34, with an extra porosity (meso-and/or macropores) system, affords excellent catalytic performance in the methanol-to-olefins (MTO) reaction, while the direct synthesis of low-silica SAPO-34 with a hierarchical structure is difficult to achieve, principally because the crystal impurities are usually formed under a low silica content in a gel precursor. Herein, low-silica SAPO-34 nanocrystals were successfully fabricated for the first time by constructing an isomorphous core−shell structure in an epitaxial growth manner. In which, low-silica, ultrasmall nanosquare-shaped SAPO-34 crystals with the same growth orientation along the (100) crystal plane compactly grow on the monocrystal SAPO-34 cores. Crucially, the external surface acid properties of the core SAPO-34 with the Si-rich outer layer are effectively modified by the low-silica SAPO-34 shell. Furthermore, the growth process and Si-substitution mechanism of the shell zeolite were comprehensively investigated. It was found that with the prolonged crystallization time, more and more coordinated Si(4Al) and Si(3Al) structures via two substitution mechanisms (SM2 and SM3) are generated in the nanocrystalline SAPO-34 shell, which endow moderate acidity of the core−shell SAPO-34. Compared to the uncoated SAPO-34, the core−shell SAPO-34 performs a longer lifespan and a higher average selectivity of light olefins (ethylene plus propylene) when applied to the MTO reaction, which is attributed to the positive effects of the luxuriant interstitial pores offering a fast diffusion channel and the moderate acid density depressing the hydrogen transfer reaction of light olefins. This work provides new insights into the fabrication of low-silica SAPO-34 nanocrystals, which are based on the rational design of the isomorphous core−shell zeolite.

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Section: Introductionmentioning

confidence: 99%

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Wang,

Dai,

Dai

et al. 2024

ACS Appl. Mater. Interfaces

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“…[1][2][3] One promising option is catalytic cracking of low-value oil fractions into light olens, 4,5 with ZSM-5 zeolites being a competitive solid acid catalyst due to their unique shape-selectivity, dened acid sites, and thermal/hydrothermal stability. [6][7][8] In practice, hydrocarbon catalytic cracking over ZSM-5 zeolites involves various tandem and parallel reactions, all contributing to the overall performance. 9 Promoting the conversion of reactants over the rationally designed zeolitic catalysts is one of the most direct methods to increase the yield of light olens, 10 wherein accessibility of these microporous crystallites is a critical consideration.…”

Section: Introductionmentioning

confidence: 99%

In situ crystal engineering on 3D-printed woodpile scaffolds: a monolith catalyst with highly accessible active sites for enhanced catalytic cracking

et al. 2023

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Growth mechanism and process intensification of Ni‐Al‐layered double hydroxide synthesized via coprecipitation

Li,

Chen,

Liu

et al. 2024

AIChE Journal

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This work systematically investigated the crystallization process of NiAl‐layered double hydroxide (NiAl‐LDH) with a Ni(II)/Al(III) ratio of 3 under different crystallization conditions. The results showed that the prepared NiAl‐LDH first exhibits sheet‐like morphology, which transforms into a hexagonal platelet with further growth. The lateral size and thickness of the prepared NiAl‐LDH are ~10–284 nm and ~2–31 nm, respectively. Based on the evolution of morphology, particle size and crystallinity, the growth mechanism of NiAl‐LDH was first proposed. The growth of NiAl‐LDH in the lateral dimension was governed by Ostwald ripening, while the increase in c direction was dominated by oriented particle attachment before precipitation and dissolution equilibrium. Afterward, the growth of NiAl‐LDH was dominated by the oriented particle attachment, leading to further growth of NiAl‐LDH. Moreover, a rotating packed bed (RPB) was first adopted to crystallize NiAl‐LDH. The results show that RPB can greatly enhance the growth of NiAl‐LDH.

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An environment-friendly and acid-degradable polymer templated synthesis of single-crystal hierarchical zeolites

Abstract: Hierarchical zeolites show great promise in green chemical and petrochemical processes, but their syntheses usually involve the use of nitrogen-/halogen-containing templates whose removal from the as-synthesized zeolites via calcination inevitably...

Cited by 9 publications

References 54 publications

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

In situ crystal engineering on 3D-printed woodpile scaffolds: a monolith catalyst with highly accessible active sites for enhanced catalytic cracking

Growth mechanism and process intensification of Ni‐Al‐layered double hydroxide synthesized via coprecipitation

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