Hierarchically structured zeolites: synthesis, mass transport properties and applications

Chen, Lihua; Li, Xiaoyun; Rooke, Joanna C.; Zhang, Yahong; Yang, Xiao‐Yu; Tang, Yi; Xiao, Feng‐Shou; Su, Bao‐Lian

doi:10.1039/c2jm31957h

Cited by 383 publications

(189 citation statements)

References 197 publications

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“…increase in conversion and/or selectivity as well as better resistance to coke formation. 37,84,202 Based on the very promising results, attempts to commercialise hierarchically porous zeolites have been initiated and are still in progress. 66,203,204 Although the results of such catalytic studies indicate the potential for technical applications for hierarchically porous systems, from the scientific point of view their interpretation in terms of mass transport/reaction relationships is still a challenging task and matter of debate.…”

Section: Discussionmentioning

confidence: 99%

Hierarchy concepts: classification and preparation strategies for zeolite containing materials with hierarchical porosity

et al. 2016

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'Hierarchy' is a property which can be attributed to a manifold of different immaterial systems, such as ideas, items and organisations or material ones like biological systems within living organisms or artificial, man-made constructions. The property 'hierarchy' is mainly characterised by a certain ordering of individual elements relative to each other, often in combination with a certain degree of branching.Especially mass-flow related systems in the natural environment feature special hierarchically branched patterns. This review is a survey into the world of hierarchical systems with special focus on hierarchically porous zeolite materials. A classification of hierarchical porosity is proposed based on the flow distribution pattern within the respective pore systems. In addition, this review might serve as a toolbox providing several synthetic and post-synthetic strategies to prepare zeolitic or zeolite containing material with tailored hierarchical porosity. Very often, such strategies with their underlying principles were developed for improving the performance of the final materials in different technical applications like adsorptive or catalytic processes. In the present review, besides on the hierarchically porous allzeolite material, special focus is laid on the preparation of zeolitic composite materials with hierarchical porosity capable to face the demands of industrial application.

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Section: Discussionmentioning

confidence: 99%

Hierarchy concepts: classification and preparation strategies for zeolite containing materials with hierarchical porosity

et al. 2016

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“…6. Despite the huge number of approaches available to prepare hierarchical zeolites, 8 the underlying principles are just three; aggregation, extraction and crystallization. 7 Some hierarchical zeolites utilize only one principle in their preparation, while others require a combination of two or even three of these principles.…”

Section: Brief Classification Of Hierarchical Zeolitesmentioning

confidence: 99%

“…However, some papers also deal with mordenite (MOR), zeolite beta (BEA) and MCM-22 (MWW). This topic has extensively been reviewed by a number of authors including Egeblad et al, 5 Perez-Ramirez et al, 6 Schwieger and co-workers, 7 Chen et al 8 and…”

Section: Introductionmentioning

confidence: 99%

Catalytic test reactions for the evaluation of hierarchical zeolites

2016

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Catalytic test reactions for the evaluation of hierarchical zeolitesStudies on the synthesis, characterization and catalytic performance of hierarchical zeolites and related porous materials are currently revitalizing the mature field of zeolite research. This review discusses the challenges in evaluating the catalytic performance of a hierarchical zeolite catalyst compared to its parent zeolite. zeolites and the facilitated access and transport in the additional meso-or macropore system. In this tutorial review, we discuss several test reactions that have been explored to show the benefit of the hierarchical pore system with respect to their suitability to prove the positive effects of hierarchical porous zeolites. It is important to note that positive effects on activity, stability and less frequently selectivity observed for hierarchically structured catalysts not necessarily are only a consequence of the additional meso-or macropores but also the number, strength and location of active sites as well as defects and impurities. With regard to these aspects, the test reaction has to be chosen carefully and potential changes in the chemistry of the catalyst have to be considered as well. In addition to the determination of conversion, yield and selectivity, we will show that the calculation of the activation energy and the determination of the Thiele modulus and the effectiveness factor are good indicators of the presence or absence of diffusion limitations in hierarchical zeolites compared to their parent materials. Key learning pointsHierarchical zeolites are an emerging technology in the mature field of industrial catalysts. Several test reactions are suggested to prove the advantage of their hierarchical structure. In addition to an increase in activity and selectivity suppression of coke formation is often observed. Concept of the Thiele modulus and the effectiveness factor is required to judge the presence of diffusion limitations in hierarchical catalysts.

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“…Hierarchically nanostructured materials are self-assembly systems that are assembled from low dimensional nanobuilding blocks, such as nanoparticles (NPs), nanowires, nanorods, nanotubes, and nanosheets [61,62]. Recently, hierarchically nanostructured TMO materials have gradually become a research hotspot in SC field because of their unique structures [63][64][65][66][67].…”

Section: Introductionmentioning

confidence: 99%