Preparation of hollow ZSM-5 crystals in the presence of polyacrylamide

Jiang, Jinlong; Yang, Yong; Duanmu, Chuansong; Ying, Xu; Feng, Li; Gu, Xing; Chen, Jing

doi:10.1016/j.micromeso.2012.06.048

Cited by 49 publications

(22 citation statements)

References 29 publications

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“…At 130 °C, the agglomerates of GQHAC evenly distribute on the outside surface of the aluminosilicate domain due to the synergistic effect of phase‐separation and the electrostatic interaction between GQHAC agglomerates and aluminosilicate domain. When the temperature is increased to 150 °C, the effect of phase‐separation can be alleviated by the higher autogentic pressure in the hydrothermal reactor and the nuclei of MFI structure will grow faster on the surface and interior of GQHAC agglomerates by consuming the nearby aluminosilicate domain . According to the theory of Ostwald Ripening, the internal nuclei of ZSM‐5 zeolite will be easily dissolved in the process of crystallization, resulting in the formation of hollow morphology with MFI structure and intracrystalline mesopores in the shell .…”

Section: Resultsmentioning

confidence: 99%

“…When the temperature is increased to 150 ∘ C, the effect of phase-separation can be alleviated by the higher autogentic pressure in the hydrothermal reactor and the nuclei of MFI structure will grow faster on the surface and interior of GQHAC agglomerates by consuming the nearby aluminosilicate domain. 43 According to the theory of Ostwald Ripening, 44 the internal nuclei of ZSM-5 zeolite will be easily dissolved in the process of crystallization, resulting in the formation of hollow morphology with MFI structure and intracrystalline mesopores in the shell. 45 As a result, the newly created mesopores go through a transformation of core-shell structure with amorphous mesopores to wileyonlinelibrary.com/jctb hollow structure with intracrystalline mesopores by increasing the crystallization temperature.…”

Section: Resultsmentioning

confidence: 99%

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Gemini‐type cationic surfactant‐directed synthesis of hollow ZSM‐5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol

Shen

Wang

Han

et al. 2017

J of Chemical Tech & Biotech

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BACKGROUND ZSM‐5 zeolites are of great importance in industrial catalysis. However, the diffusion limitations caused by small pore opening restrict the extent of catalytic conversions over conventional ZSM‐5. Many studies have shown that mass transfer in zeolite channels can be improved by controlling the morphology or creating additional mesoporosity. Here, the catalytic performance is further improved by the creation of hollow structure and intracrystalline mesopores in ZSM‐5 zeolite. RESULTS The characterization results demonstrated that hollow ZSM‐5 with intracrystalline mesopores can be synthesized by using a simple one‐step hydrothermal strategy with a commercial gemini‐type cationic surfactant containing hydrophilic hydroxyl groups. Compared with the Fe‐substituted conventional ZSM‐5, the Fe‐substituted hollow ZSM‐5 with intracrystalline mesopores show remarkably enhanced catalytic performance in the hydroxylation of phenol. About 52.2% conversion of phenol can be obtained with almost 96.8% selectivity to dihydroxybenzenes. The catalytic activity remained almost unchanged after five cycles. CONCLUSION The newly created hollow structure and intracrystalline mesopores in ZSM‐5 zeolite showed enhanced catalytic activity and reusability for the hydroxylation of phenol, which is higher than most reported systems. The prepared catalyst is a promising alternative material for the hydroxylation of phenol. © 2017 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Gemini‐type cationic surfactant‐directed synthesis of hollow ZSM‐5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol

Shen

Wang

Han

et al. 2017

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

show abstract

“…The surface to core crystallization mechanism was proposed as the principal mechanism of hollow structure formation: The internal part of an initially formed organic/inorganic composite is getting consumed by the nanocrystals accumulated on the external surface. These surface nanocrystals are formed faster in hydrothermal conditions due to the easy access to the nutrient from the bulk gel . Such a mechanism has also been observed for converting self‐assembled spherical nanocrystals into hollow zeolite …”

Section: Synthesis Of Hollow and Yolk–shell Zeolitic Materialsmentioning

confidence: 82%

“…Hollow zeolitic materials have also been synthesized following the in situ seed‐free crystallization method using solid hard templates, nanocrystal self‐assembly via adjusting synthesis conditions and compositions, and the dual‐templating method . These studies are summarized in Table 6 .…”

Section: Synthesis Of Hollow and Yolk–shell Zeolitic Materialsmentioning

confidence: 99%

Synthesis of Engineered Zeolitic Materials: From Classical Zeolites to Hierarchical Core–Shell Materials

2018

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The term "engineered zeolitic materials" refers to a class of materials with a rationally designed pore system and active-sites distribution. They are primarily made of crystalline microporous zeolites as the main building blocks, which can be accompanied by other secondary components to form composite materials. These materials are of potential importance in many industrial fields like catalysis or selective adsorption. Herein, critical aspects related to the synthesis and modification of such materials are discussed. The first section provides a short introduction on classical zeolite structures and properties, and their conventional synthesis methods. Then, the motivating rationale behind the growing demand for structural alteration of these zeolitic materials is discussed, with an emphasis on the ongoing struggles regarding mass-transfer issues. The state-of-the-art techniques that are currently available for overcoming these hurdles are reviewed. Following this, the focus is set on core-shell composites as one of the promising pathways toward the creation of a new generation of highly versatile and efficient engineered zeolitic substances. The synthesis approaches developed thus far to make zeolitic core-shell materials and their analogues, yolk-shell, and hollow materials, are also examined and summarized. Finally, the last section concisely reviews the performance of novel core-shell, yolk-shell, and hollow zeolitic materials for some important industrial applications.

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“…For soft-template method, fewer templates are needed to induce the generation of hollow zeolite compared with hard-template method. Jiang et al [30] prepared hollow ZSM-5 crystals through hydrothermal crystallization method in the presence of polyacrylamide (PAM) as the soft template under the condition of low crystallization temperature (120 °C) and high PAM concentration. Wang et al [31] synthesized the hollow microsphere ZSM-5 zeolite through a dissolution-recrystallization procedure with the assistance of organosilanes.…”

Section: Hollow Zsm-5 Zeolitementioning

confidence: 99%

Strategies to Enhance the Catalytic Performance of ZSM-5 Zeolite in Hydrocarbon Cracking: A Review

2017

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ZSM-5 zeolite is widely used in catalytic cracking of hydrocarbon, but the conventional ZSM-5 zeolite deactivates quickly due to its simple microporous and long diffusion pathway. Many studies have been done to overcome these disadvantages recently. In this review, four main approaches for enhancing the catalytic performance, namely synthesis of ZSM-5 zeolite with special morphology, hierarchical ZSM-5 zeolite, nano-sized ZSM-5 zeolite and optimization of acid properties, are discussed. ZSM-5 with special morphology such as hollow, composite and nanosheet structure can effectively increase the diffusion efficiency and accessibility of acid sites, giving high catalytic activity. The accessibility of acid sites and diffusion efficiency can also be enhanced by introducing additional mesopores or macropores. By decreasing the crystal size to nanoscale, the diffusion length can be shortened. The catalytic activity increases and the amount of carbon deposition decreases with the decrease of crystal size. By regulating the acid properties of ZSM-5 with element or compound modification, the overreaction of reactants and formation of carbon deposition could be suppressed, thus enhancing the catalytic activity and light alkene selectivity. Besides, some future needs and perspectives of ZSM-5 with excellent cracking activity are addressed for researchers' consideration.

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Preparation of hollow ZSM-5 crystals in the presence of polyacrylamide

Cited by 49 publications

References 29 publications

Gemini‐type cationic surfactant‐directed synthesis of hollow ZSM‐5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol

Gemini‐type cationic surfactant‐directed synthesis of hollow ZSM‐5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol

Synthesis of Engineered Zeolitic Materials: From Classical Zeolites to Hierarchical Core–Shell Materials

Strategies to Enhance the Catalytic Performance of ZSM-5 Zeolite in Hydrocarbon Cracking: A Review

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