Hydrothermal Zeolite Synthesis

Kirschhock, Christine; Feijen, Eddy J. P.; Jacobs, Pierre; Martens, Jürgen

doi:10.1002/9783527610044.hetcat0010

Cited by 18 publications

(23 citation statements)

References 90 publications

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“…Treatment of the gel under autogenic conditions (high temperature and pressure) in the presence of the structure-directing agent leads to formation of the zeolite powder. Thermal removal of the residual SDA from the pores, following filtration from the remaining sol gel, yields the final porous, crystalline zeolite [ 63 ]. The synthesis of porous metallosilicates containing Lewis acidic centres is also achieved via hydrothermal synthesis.…”

Section: Perspectives and Pertaining Challengesmentioning

confidence: 99%

Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Hammond¹,

Padovan²,

Tarantino³

2018

R. Soc. open sci.

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Porous silicates containing dilute amounts of tri-, tetra- and penta-valent metal sites, such as TS-1, Sn-β and Fe-ZSM-5, have recently emerged as state of the art catalysts for a variety of sustainable chemical transformations. In contrast with their aluminosilicate cousins, which are widely employed throughout the refinery industry for gas-phase catalytic transformations, such metallosilicates have exhibited unprecedented levels of performance for a variety of liquid-phase catalytic processes, including the conversion of biomass to chemicals, and sustainable oxidation technologies with H2O2. However, despite their unique levels of performance for these new types of chemical transformations, increased utilization of these promising materials is complicated by several factors. For example, their utilization in a liquid, and often polar, medium hinders process intensification (scale-up, catalyst deactivation). Moreover, such materials do not generally exhibit the active-site homogeneity of conventional aluminosilicates, and they typically possess a wide variety of active-site ensembles, only some of which may be directly involved in the catalytic chemistry of interest. Consequently, mechanistic understanding of these catalysts remains relatively low, and competitive reactions are commonly observed. Accordingly, unified approaches towards developing more active, selective and stable porous metallosilicates have not yet been achieved. Drawing on some of the most recent literature in the field, the purpose of this mini review is both to highlight the breakthroughs made with regard to the use of porous metallosilicates as heterogeneous catalysts for liquid-phase processing, and to highlight the pertaining challenges that we, and others, aim to overcome during the forthcoming years.

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Section: Perspectives and Pertaining Challengesmentioning

confidence: 99%

Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Hammond¹,

Padovan²,

Tarantino³

2018

R. Soc. open sci.

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“…a batch. [1][2][3]5 The Si-and Al-source are the amorphous or soluble raw material from which the crystalline aluminosilicate will be formed. If zeotype molecular sieves are synthesized, an additional or different heteroatom source needs to be added such as phosphoric acid when synthesizing SAPOs.…”

Section: Conventional Hydrothermal Synthesismentioning

confidence: 99%

“…This higher temperature is accompanied by an increased concentration of soluble Si-and Al-species, going from a stable, over a metastable, towards a labile phase. 5 In this latter phase, it is possible to form new crystals. This phenomenon is called supersaturation and is often, together with reaching the final synthesis temperature in the liquor, seen as the start of the induction period (τ).…”

Section: Conventional Hydrothermal Synthesismentioning

confidence: 99%

“…In the end, zeolites crystals will further grow at the crystalliquor interface via successive monomer addition at the expense of the amorphous Si-and Al-source (or solution) or by aggregation of available nanoparticles in non-classical ways. [3][4][5][8][9][10][11][12][13][14] In summary, molecular sieves synthesis in general consists of a complex sequence of steps. For a more detailed understanding, the reader is referred to the reviews of Corma and Davis (2004) 2 , and Cundy and Cox (2003 and 2005) 1,3 and the book "zeolites and catalysis" of Cejka, Corma and Zones (2010) 4 .…”

Section: Conventional Hydrothermal Synthesismentioning

confidence: 99%

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Zeolite Synthesis under Nonconventional Conditions: Reagents, Reactors, andModi Operandi

Deneyer

Devos

et al. 2020

Chem. Mater.

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A myriad of tetrahedral molecular sieve frameworks, often siliceous, can be calculated in silico. Only a tiny fraction (<0.1%) of these can be synthesized on purpose. Only a small fraction of these available frameworks, mostly those composed of only Si and Al as T-atoms, i.e. true zeolites, are used commercially. A gap thus exists between what should be possible (thermodynamically) and what can be produced (kinetically) and used in real life. Even if a synthesis is successful (in industry or academia), flexibility with regard to synthesis parameters -in terms of time, amount of unit operations, OSDA-efficiency, etc. -as well as the obtained material properties -in terms of Si/Al ratio, Al-distribution, T-atom variety, crystal size, etc. -remains limited. These limitations are not surprising since conventional zeolite syntheses, i.e. hydrothermal synthesis in batch from amorphous or soluble Si-and Al-sources, have limited degrees of freedom (DOF). Typically, the type of ingredients, their ratios, a constant temperature, synthesis time and the absence or presence of agitation are varied. In order to take new steps towards more cost-competitive syntheses, and more importantly, zeolites with a greater flexibility in terms of structural properties, this review highlights all DOFs that can be introduced in addition to or on top of the conventional way of synthesis. By doing this, a distinction is made between non-conventional DOFs that influence the chemistry of the system (e.g. interzeolite conversion, charge density mismatch approach, ionothermal or free-radical assisted synthesis) and non-conventional DOFs that influence the physical environment (e.g. ultrasounds, alternative energy via microwaves or continuous set-ups). The review concludes with learnings, practical insights and future opportunities. In other words: which zeolite synthesis strategies really make a difference and which ones are just tweaking around the edges?

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“…Most zeolites are crystallized under alkaline condition with the basic Na 2 O-Al 2 O 3 -SiO 2 -H 2 O systems, and the pH of the synthesis solution is generally between 9 and 13 [83]. The alkalinity of the solution can be defined as OH − /Si ratio or Na 2 O/H 2 O ratio [84].…”

Section: Alkalinity Of the Synthesis Solutionmentioning

confidence: 99%

Methods and synthesis parameters affecting the formation of FAU type zeolite membrane and its separation performance: a review

Nazir

Yeong

Chew

2020

Journal of Asian Ceramic Societies

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The development of Faujasite (FAU) zeolite membranes has been a subject of interest for various application due to the uniform pore's characteristic, excellent thermal, and chemical stability as well as catalytic and ion-exchange properties of FAU zeolite membranes. However, the synthesis of FAU zeolite membranes with minimum defects is still challenging as there are multiple variables in the synthesis process which need to be controlled. This review started with an overview on zeolites, zeolite membranes, and their applications. Then, various methods used for the preparation of FAU zeolite membrane are discussed. Subsequently, the variation of synthesis techniques and parameters for obtaining high quality of FAU zeolite membrane are reviewed. Then, the parameters affecting the formation of FAU zeolite membrane are highlighted.

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Hydrothermal Zeolite Synthesis

Abstract: The sections in this article are Introduction Zeolitization in General Key Steps in Zeolite Synthesis Key Parameters Governing Zeolitization A Molar Composition B Mineralizing Agent … Show more

Cited by 18 publications

References 90 publications

Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Zeolite Synthesis under Nonconventional Conditions: Reagents, Reactors, andModi Operandi

Methods and synthesis parameters affecting the formation of FAU type zeolite membrane and its separation performance: a review

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