Editing Zeolite

{{Short description|Microporous, aluminosilicate mineral group}}
[[File:Estonian Museum of Natural History Specimen No 203540 photo (g232 g232-25 jpg).jpg|thumb|Zeolite exhibited in the [[Estonian Museum of Natural History]]]]
'''Zeolite''' is a group of several [[Microporous material|microporous]], crystalline [[aluminosilicate]] minerals commonly used as commercial [[adsorption|adsorbents]] and [[Catalysis|catalyst]]s.<ref>{{Cite web|url=http://www.grace.com/EngineeredMaterials/MaterialSciences/Zeolites/ZeoliteStructure.aspx|title=Zeolite Structure|date=2006|website=GRACE.com|publisher=W. R. Grace & Co.|archive-url=https://web.archive.org/web/20090215184310/http://www.grace.com/EngineeredMaterials/MaterialSciences/Zeolites/ZeoliteStructure.aspx|archive-date=15 February 2009|url-status=dead|access-date=8 Feb 2019}}</ref> They mainly consist of [[silicon]], [[aluminium]], [[oxygen]], and have the general formula {{chem|M|1/n|n+|(AlO|2|)|-|(SiO|2|)|x}}･y{{chem|H|2|O}} where {{chem|M|1/n|n+}} is either a metal ion or H<sup>+</sup>.

The term was originally coined in 1756 by [[Sweden|Swedish]] [[mineralogy|mineralogist]] [[Axel Fredrik Cronstedt]], who observed that rapidly heating a material, believed to have been [[stilbite]], produced large amounts of steam from water that had been [[Adsorption|adsorbed]] by the material. Based on this, he called the material ''zeolite'', from the [[Greek language|Greek]] {{lang|grc|ζέω (zéō)}}, meaning "to boil" and {{lang|grc|λίθος (líthos)}}, meaning "stone".<ref>{{Cite journal|vauthors=Cronstedt AF|date=1756|title=Natural zeolite and minerals|journal=Svenska Vetenskaps Akademiens Handlingar Stockholm|volume=17|pages=120}}</ref>

Zeolites occur naturally, but are also produced industrially on a large scale. {{As of|2018|12}}, 253 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known.<ref name="IZA-SC">{{Cite web|url=http://www.iza-structure.org/databases/|title=Database of Zeolite Structures|date=2017|website=iza-structure.org|publisher=International Zeolite Association|access-date=24 May 2021}}</ref><ref>{{Cite web|url=http://webmineral.com/danaclass.shtml|title=Minerals Arranged by the New Dana Classification|website=webmineral.com|access-date=8 Feb 2019}}</ref> Every new zeolite structure that is obtained is examined by the International Zeolite Association Structure Commission (IZA-SC) and receives a three-letter designation.<ref>{{Cite web|url=http://www.iza-structure.org/index.htm|title=News from the Structure Commission|date=2018|website=IZA Structure Commission|access-date=8 Feb 2018}}</ref>

==Characteristics==
===Properties===
[[File:Zeolite structure as an assembly of tetrahedra.png|thumb|458x458px|Microscopic structure of a zeolite ([[mordenite]]) framework, assembled from corner-sharing {{chem|SiO|4}} tetrahedra. Sodium is present as an extra-framework cation (in green). Si atoms can be partially replaced by Al or other tetravalent metals.]]

Zeolites are white solids with ordinary handling properties, like many routine [[aluminosilicate]] minerals, e.g. [[feldspar]]. They have the general formula {{chem2|(MAlO2)(SiO2)_{x}(H2O)_{y}|}} where M<sup>+</sup> is usually H<sup>+</sup> and Na<sup>+</sup>. The Si/Al ratio is variable, which provides a means to tune the properties. Zeolites with a Si/Al ratios higher than about 3 are classified as '''high-silica zeolites''', which tend to be more hydrophobic. The H<sup>+</sup> and Na<sup>+</sup> can be replaced by diverse cations, because zeolites have [[ion exchange]] properties. The nature of the cations influences the porosity of zeolites. 

Zeolites have microporous structures with a typical diameter of 0.3–0.8&nbsp;nm. Like most aluminosilicates, the framework is formed by linking of aluminum and silicon atoms by oxides. This linking leads to a 3-dimensional network of Si-O-Al, Si-O-Si, and Al-O-Al linkages. The aluminum centers are negatively charged, which requires an accompanying cation. These cations are hydrated during the formation of the materials. The hydrated cations interrupt the otherwise dense network of Si-O-Al, Si-O-Si, and Al-O-Al linkage, leading to regular water-filled cavities. Because of the porosity of the zeolite, the water can exit the material through channels. Because of the rigidity of the zeolite framework, the loss of water does not result in collapse of the cavities and channels. This aspect – the ability to generate voids within the solid material – underpins the ability of zeolites to function as catalysts. They possess high physical and chemical stability due to the large covalent bonding contribution. They have excellent hydrophobicity and are suited for adsorption of bulky, hydrophobic molecules such as hydrocarbons. In addition to that, high-silica zeolites are {{Chem|H|+}} exchangeable, unlike natural zeolites, and are used as [[solid acid catalyst]]s. The acidity is strong enough to protonate hydrocarbons and high-silica zeolites are used in acid catalysis processes such as [[fluid catalytic cracking]] in petrochemical industry.<ref>{{Greenwood&Earnshaw2nd}} </ref>
[[File:Zeolite Mordenite (with Al substitution).png|thumb|Zeolite Mordenite with some Si atoms substituted with Al atoms. ]]
===Framework structure===
[[File:Zeolite4ring.svg|350px|thumb|Three ways to represent the oxygen 4-membered ring structure of silicate compounds.]]
[[File:FAU and LTA.png|350px|thumb|Comparison of framework structures of LTA-type zeolite (left) and FAU-type zeolite (right)]]
The structures of hundreds of zeolites have been determined. Most do not occur naturally. For each structure, the International Zeolite Association (IZA) gives a three-letter code called framework type code (FTC).<ref name="IZA-SC" /> For example, the major molecular sieves, 3A, 4A and 5A, are all LTA (Linde Type A). Most commercially available natural zeolites are of the MOR, HEU or ANA-types.

An example of the notation of the ring structure of zeolite and other silicate materials is shown in the upper right figure. The middle figure shows a common notation using [[structural formula]]. The left figure emphasizes the SiO{{sub|4}} tetrahedral structure. Connecting oxygen atoms together creates a four-membered ring of oxygen (blue bold line). In fact, such a ring substructure is called '''four membered ring''' or simply '''four-ring'''. The figure on the right shows a 4-ring with Si atoms connected to each other, which is the most common way to express the topology of the framework.

The figure on the right compares the typical framework structures of [[LTA-type zeolite|LTA]] (left) and [[Faujasite|FAU]] (right). Both zeolites share the [[Truncated octahedron|truncated octahedral]] structure ([[sodalite]] cage) (purple line). However, the way they are connected (yellow line) is different: in LTA, the four-membered rings of the cage are connected to each other to form a skeleton, while in FAU, the six-membered rings are connected to each other. As a result, the pore entrance of LTA is an 8-ring (0.41&nbsp;nm<ref name="IZA-SC" />) and belongs to the '''small pore zeolite''', while the pore entrance of FAU is a 12-ring (0.74&nbsp;nm<ref name="IZA-SC" />) and belongs to the '''large pore zeolite''', respectively. Materials with a 10-ring are called '''medium pore zeolites''', a typical example being [[ZSM-5]] (MFI).

Although more than 200 types of zeolites are known, only about 100 types of aluminosilicate are available. In addition, there are only a few types that can be synthesized in industrially feasible way and have sufficient thermal stability to meet the requirements for industrial use. In particular, the FAU (faujasite, USY), <sup>*</sup>BEA (beta), MOR (high-silica mordenite), MFI (ZSM-5), and FER (high-silica ferrierite) types are called the '''big five''' of high silica zeolites,<ref>{{Cite journal|title=An Overview on Zeolite Shaping Technology and Solutions to Overcome Diffusion Limitations|journal=Catalysts|issue=8|pages=163|year=2018}}</ref> and industrial production methods have been established.

===Porosity===
The term [[molecular sieve]] refers to a particular property of these materials, i.e., the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels. These are conventionally defined by the ring size of the aperture, where, for example, the term "eight-ring" refers to a closed-loop that is built from eight tetrahedrally coordinated silicon (or aluminium) atoms and eight oxygen atoms. These rings are not always perfectly symmetrical due to a variety of causes, including strain induced by the bonding between units that are needed to produce the overall structure or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the pores in many zeolites are not cylindrical.

===Isomorphous substitution===
[[Isomorphous substitution]] of Si in zeolites can be possible for some heteroatoms such as [[titanium]],<ref name="ref12">{{Ref patent|country=US|number=4410501A|status=patent|gdate=1979-12-21|title = Preparation of porous crystalline synthetic material {{sic|comprised |hide=y|of}}} silicon and titanium oxides}}</ref> [[zinc]]<ref name="ref13">{{Ref patent|country=US|number=2016243531A1|status=patent|gdate=2015-02-24|title = Processes for preparing zincoaluminosilicates with aei, cha, and gme topologies and compositions derived therefrom}}</ref> and [[germanium]].<ref name="ref14">{{Cite journal|title=Post-Synthesis Stabilization of Germanosilicate Zeolites ITH, IWW, and UTL by Substitution of Ge for Al|url=https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/chem.201603434|journal=Chemistry: A European Journal|volume=22|issue=48|pages=17377–17386|year=2016|doi=10.1002/chem.201603434 |last1=Shamzhy |first1=Mariya V. |last2=Eliašová |first2=Pavla |last3=Vitvarová |first3=Dana |last4=Opanasenko |first4=Maksym V. |last5=Firth |first5=Daniel S. |last6=Morris |first6=Russell E. |pmid=27754569 |hdl=10023/11880 |hdl-access=free }}</ref> Al atoms in zeolites can be also structurally replaced with [[boron]]<ref name="ref15">{{Ref patent|country=US|number=5187132A|status=patent|gdate=1993-02-16|title = Preparation of borosilicate zeolites}}</ref> and [[gallium]].<ref name="ref16">{{Cite journal|title=Incorporation of Gallium into Zeolites: Syntheses, Properties and Catalytic Application|journal=Chem. Rev.|issue=100|pages=2303–2405|year=2000}}</ref>

The [[silicoaluminophosphate]] type (AlPO molecular sieve),<ref name="ref17">{{Cite journal|title=Crystal Structure of Tetrapropylammonium Hydroxide-Aluminium Phosphate Number 5|journal=ACS Sym. Ser.|issue=218|pages=109–118|year=1983}}</ref> in which Si is isomorphous with Al and P and Al is isomorphous with Si, and the gallogermanate<ref name="ref18">{{Cite journal|title=Hydrothermal synthesis and structural characterization of zeolite-like structures based on gallium and aluminium germanates|journal=J. Am. Chem. Soc.|issue=120|pages=13389–13397|year=1998}}</ref> and others are known.

==Natural occurrence==
[[File:Thomsonite-61017.jpg|thumb|left|A form of [[thomsonite]] (one of the rarest zeolites) from India]]

Some of the more common mineral zeolites are [[analcime]], [[chabazite]], [[clinoptilolite]], [[heulandite]], [[natrolite]], [[phillipsite]], and [[stilbite]]. An example of the mineral formula of a zeolite is: {{Chem2|Na2Al2Si3O10}}·2H<sub>2</sub>O, the formula for [[natrolite]].

Natural zeolites form where [[volcanic]] rocks and [[volcanic ash|ash]] layers react with [[alkaline]] groundwater. Zeolites also crystallize in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, [[quartz]], or other zeolites. For this reason, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential.{{Citation needed|date=June 2021|reason=No citation for anything in paragraph}}

Zeolites transform to other minerals under [[weathering]], [[hydrothermal alteration]] or [[metamorphism|metamorphic]] conditions. Some examples:<ref name="Tschernich-1992">{{Cite book|url=https://www.mindat.org/article.php/507/Mindat%27s+15th+Birthday+and+a+present+for+everyone|title=Zeolites of the World|vauthors=Tschernich RW|publisher=Geoscience Press|year=1992|isbn=9780945005070|url-access=registration}}</ref>
* The sequence of [[silica]]-rich [[volcanic rock]]s commonly progresses from:
** [[Clay]] → quartz → [[mordenite]]–[[heulandite]] → [[epistilbite]] → [[stilbite]] → [[thomsonite]] → [[mesolite]] → [[scolecite]] → [[chabazite]] → [[calcite]].{{citation needed|reason= Clay becomes quartz???|date=October 2018}}
* The sequence of silica-poor volcanic rocks commonly progresses from:
** [[Cowlesite]] → [[levyne]] → [[offretite]] → [[analcime]] → [[thomsonite]] → [[mesolite]] → [[scolecite]] → [[chabazite]] → [[calcite]].

=== Gemstones ===
[[File:Thomsonite-Ca-55547.jpg|thumb|upright|Polished thomsonite]]
[[Thomsonite]]s, one of the rarer zeolite minerals, have been collected as [[gemstone]]s from a series of [[lava]] flows along [[Lake Superior]] in [[Minnesota]] and, to a lesser degree, in [[Michigan]]. Thomsonite nodules from these areas have [[erosion|eroded]] from [[basalt]] lava flows and are collected on beaches and by scuba divers in Lake Superior.

These thomsonite nodules have concentric rings in combinations of colors: black, white, orange, pink, purple, red, and many shades of green. Some nodules have copper inclusions and rarely will be found with [[copper]] "eyes". When polished by a [[lapidary]], the thomsonites sometimes displays a "cat's eye" effect ([[chatoyancy]]).<ref name="Dietrich">{{cite web|url=http://stoneplus.cst.cmich.edu/thomsonite.htm|title=Thomsonite|author=Dietrich RV|date=2005|website=GemRocks|access-date=2 Oct 2013}}</ref>

==Production==
The first synthetic structure was reported by [[Richard Barrer]].<ref>{{Cite journal |last=Barrer |first=R. M. |date=1948-01-01 |title=33. Synthesis of a zeolitic mineral with chabazite-like sorptive properties |url=https://pubs.rsc.org/en/content/articlelanding/1948/jr/jr9480000127 |journal=Journal of the Chemical Society (Resumed) |language=en |pages=127–132 |doi=10.1039/JR9480000127 |pmid=18906370 |issn=0368-1769}}</ref> Industrially important zeolites are produced synthetically. Typical procedures entail heating aqueous solutions of [[alumina]] and [[silica]] with [[sodium hydroxide]]. Equivalent reagents include [[sodium aluminate]] and [[sodium silicate]]. Further variations include the use of structure directing agents (SDA) such as [[quaternary ammonium cation]]s.<ref>{{cite book|title=Inorganic Syntheses: Nonmolecular Solids|vauthors=Rollmann LD, Valyocsik EW, Shannon RD|publisher=Wiley & Sons|year=1995|isbn=9780470132616|veditors=Murphy DW, Interrante LV|volume=30|location=New York|pages=227–234|chapter=Zeolite Molecular Sieves|doi=10.1002/9780470132616.ch43}}</ref>

Synthetic zeolites hold some key advantages over their natural analogs. The synthetic materials are manufactured in a uniform, phase-pure state. It is also possible to produce zeolite structures that do not appear in nature. Zeolite A is a well-known example. Since the principal raw materials used to manufacture zeolites are silica and alumina, which are among the most abundant mineral components on earth, the potential to supply zeolites is virtually unlimited.

===Ore mining===
[[File:Natrolit, Gracza 2Polska.jpg|thumb|[[Natrolite]] from Poland]]
{{As of | 2016}}, the world's annual production of natural zeolite approximates 3 million [[tonne]]s. Major producers in 2010 included [[China]] (2 million tonnes), [[South Korea]] (210,000 t), [[Japan]] (150,000 t), [[Jordan]] (140,000 t), [[Turkey]] (100,000 t) [[Slovakia]] (85,000 t) and the [[United States]] (59,000 t).<ref>{{Cite web|url=https://minerals.usgs.gov/minerals/pubs/commodity/zeolites/mcs-2011-zeoli.pdf |archive-url=https://web.archive.org/web/20110608074556/http://minerals.usgs.gov/minerals/pubs/commodity/zeolites/mcs-2011-zeoli.pdf |archive-date=2011-06-08 |url-status=live|title=Zeolites (natural)|date=2011|website=[[United States Geological Survey|USGS]] Mineral Commodity Summaries|access-date=8 Feb 2019}}</ref> The ready availability of zeolite-rich rock at low cost and the shortage of competing minerals and rocks are probably the most important factors for its large-scale use. According to the [[United States Geological Survey]], it is likely that a significant percentage of the material sold as zeolites in some countries is ground or sawn volcanic [[tuff]] that contains only a small amount of zeolites. These materials are used for construction, e.g. [[dimension stone]] (as an altered volcanic tuff), lightweight [[aggregate (composite)|aggregate]], [[Pozzolana|pozzolanic cement]], and [[soil conditioner]]s.<ref name="Virta-2011">{{Cite web|url=https://minerals.usgs.gov/minerals/pubs/commodity/zeolites/myb1-2009-zeoli.pdf |archive-url=https://web.archive.org/web/20110608074402/http://minerals.usgs.gov/minerals/pubs/commodity/zeolites/myb1-2009-zeoli.pdf |archive-date=2011-06-08 |url-status=live|title=2009 Minerals Yearbook - Zeolites|last=Virta RL|date=2011|publisher=[[United States Geological Survey|USGS]]|access-date=8 Feb 2019}}</ref>

===Synthesis===
[[File:Ceolite nax.JPG|thumb|left|Synthetic zeolite]]
Over 200 synthetic zeolites have been reported.<ref>{{Cite journal|vauthors=Earl DJ, Deem MW|date=2006|title=Toward a Database of Hypothetical Zeolite Structures|journal=[[Industrial & Engineering Chemistry Research|Ind. Eng. Chem. Res.]]|volume=45|issue=16|pages=5449–5454|doi=10.1021/ie0510728|issn=0888-5885}}</ref> Most zeolites have aluminosilicate frameworks but some incorporate germanium, iron, gallium, boron, zinc, tin, and titanium.<ref>{{Cite book|url=https://www.springer.com/us/book/9780751404807|title=Molecular Sieves - Principles of Synthesis and Identification|last=Szostak|first=Rosemarie|publisher=Springer|year=1998|isbn=9780751404807|series=Van Nostrand Reinhold Electrical/Computer Science and Engineering Series|language=en|name-list-style=vanc}}</ref> Zeolite synthesis involves [[sol-gel]]-like processes. The product properties depend on reaction mixture composition, pH of the system, [[operating temperature]], pre-reaction 'seeding' time, reaction time as well as the templates used. In the sol-gel process, other elements (metals, metal oxides) can be easily incorporated.

== Applications ==

Zeolites are widely used as catalysts and [[Sorbent|sorbents]].<ref>{{cite journal|author1=P. Chatterjee |author2=Y. Han |author3=T. Kobayashi |author4=K. Verma| author5=M. Mais| author6=R. Behera| author7=T. Johnson| author8=T. Prozorov| author9=J. Evans| author10=I.I. Slowing| author11=W. Huang|title=Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture|journal= ACS Appl. Mater. Interfaces| year=2023|volume=15 |issue=46 |pages=54192–54201 |doi=10.1021/acsami.3c14560|pmid=37934618 |s2cid=265050410 }}</ref><ref>{{Cite book|url=https://books.google.com/books?id=x-vwPoX4YYkC|title=Zeolite Catalysts: Principles and Applications|last=Bhatia|first=Subhash|publisher=CRC Press|year=1989|isbn=9780849356285|location=Boca Raton|name-list-style=vanc}}</ref> In chemistry, zeolites are used as [[Zeolite membrane|membranes]] to separate [[molecule]]s (only molecules of certain sizes and shapes can pass through), and as traps for molecules so they can be analyzed.

Research into and development of the many [[biochemical]] and [[biomedical]] applications of zeolites, particularly the naturally occurring species [[heulandite]], [[clinoptilolite]], and [[chabazite]] has been ongoing.<ref>{{Cite book|title=Handbook of Zeolite Science and Technology|publisher=CRC Press|year=2003|isbn=9780824740207|veditors=Auerbach SM, Carrado KA, Dutta PK|location=Boca Raton|pages=16}}</ref>

=== Ion-exchange, water purification and softening ===

Zeolites are widely used as [[ion-exchange]] beds in domestic and commercial [[water purification]], [[Water softening|softening]], and other applications.

Evidence for the oldest known zeolite water purification filtration system occurs in the undisturbed sediments of the Corriental reservoir at the Maya city of [[Tikal]], in northern Guatemala.<ref>Tankersley, K.B., Dunning, N.P., Carr, C. et al. Zeolite water purification at Tikal, an ancient Maya city in Guatemala. Sci Rep 10, 18021 (2020). https://doi.org/10.1038/s41598-020-75023-7</ref>

Earlier, polyphosphates were used to soften hard water. The polyphosphates forms complex with metal ions like Ca<sup>2+</sup> and Mg<sup>2+</sup> to bind them up so that they could not interfere in cleaning process. However, when this phosphate rich water goes in main stream water, it results in [[eutrophication]] of water bodies and hence use of polyphosphate was replaced with use of a synthetic zeolite.

The largest single use for zeolite is the global laundry [[detergent]] market. Zeolites are used in laundry detergent as water softeners, removing Ca<sup>2+</sup> and Mg<sup>2+</sup> ions which would otherwise precipitate from the solution. The ions are retained by the zeolites which releases Na<sup>+</sup> ions into the solution, allowing the laundry detergent to be effective in areas with hard water.<ref name="Burrows-2009">{{Cite book |url=https://archive.org/details/chemistryintrodu0000burr/mode/2up |title=Chemistry3 : introducing inorganic, organic and physical chemistry|date=2009|publisher=Oxford University Press|author=Andrew Burrows |author2=John Holman |author3=Andrew Parsons |author4=Gwen Pilling |author5=Gareth Price |isbn=978-0-19-927789-6|location=Oxford|page=253|oclc=251213960}}</ref>

=== Catalysis ===

Synthetic zeolites, like other mesoporous materials (e.g., [[MCM-41]]), are widely used as [[catalyst]]s in the [[petrochemical industry]], such as in fluid catalytic [[Cracking (chemistry)|cracking]] and [[hydrocracking]]. Zeolites confine molecules into small spaces, which causes changes in their structure and reactivity. The acidic forms of zeolites prepared are often powerful solid-state [[solid acid]]s, facilitating a host of acid-catalyzed reactions, such as [[isomerization]], [[alkylation]], and cracking.

[[Catalytic cracking]] uses a reactor and a regenerator. Feed is injected onto a hot, fluidized catalyst where large [[gasoil]] molecules are broken into smaller gasoline molecules and [[olefins]]. The vapor-phase products are separated from the catalyst and distilled into various products. The catalyst is circulated to a regenerator, where the air is used to burn coke off the surface of the catalyst that was formed as a byproduct in the cracking process. The hot, regenerated catalyst is then circulated back to the reactor to complete its cycle.

Zeolites containing cobalt [[nanoparticle]]s have applications in the recycling industry as a catalyst to break down [[polyethylene]] and [[polypropylene]], two widely used plastics, into [[propane]].<ref>{{Cite web |title=New process could enable more efficient plastics recycling |url=https://news.mit.edu/2022/plastics-recycling-cobalt-catalyst-1006 |access-date=2023-04-22 |website=MIT News {{!}} Massachusetts Institute of Technology |date=6 October 2022 |language=en}}</ref>

=== Nuclear waste reprocessing ===
[[File:U.S. Department of Energy - Science - 463 015 001 (10190451506).jpg|right|thumb|A researcher at [[Sandia National Laboratories]] examines vials of SOMS (Sandia Octahedral Molecular Sieve), a zeolite that shows potential for radioactive waste and industrial metals cleanup.]]

Zeolites have been used in advanced [[nuclear reprocessing]] methods, where their micro-porous ability to capture some ions while allowing others to pass freely allows many [[fission product]]s to be efficiently removed from the waste and permanently trapped. Equally important are the mineral properties of zeolites. Their alumino-silicate construction is extremely durable and resistant to radiation, even in porous form. Additionally, once they are loaded with trapped fission products, the zeolite-waste combination can be hot-pressed into an extremely durable ceramic form, closing the pores and trapping the waste in a solid stone block. This is a waste form factor that greatly reduces its hazard, compared to conventional reprocessing systems. Zeolites are also used in the management of leaks of radioactive materials. For example, in the aftermath of the [[Fukushima Daiichi nuclear disaster]], sandbags of zeolite were dropped into the seawater near the power plant to adsorb the radioactive [[cesium-137]] that was present in high levels.<ref>{{Cite news|url=https://www.nytimes.com/2011/04/17/world/asia/17nuke.html|title=Level of Radioactive Materials Rises Near Japan Plant|last=The Associated Press|date=16 Apr 2011|work=[[The New York Times|NYTimes]]|issn=0362-4331}}</ref>

===Gas separation and storage===
Zeolites have the potential of providing precise and specific separation of gases, including the removal of H<sub>2</sub>O, CO<sub>2</sub>, and SO<sub>2</sub> from low-grade [[natural gas]] streams. Other separations include [[noble gases]], N<sub>2</sub>, O<sub>2</sub>, [[freon]], and [[formaldehyde]].

On-board oxygen generating systems (OBOGS) and [[oxygen concentrator]]s use zeolites in conjunction with [[pressure swing adsorption]] to remove nitrogen from compressed air to supply oxygen for aircrews at high altitudes, as well as home and portable oxygen supplies.<ref>{{Cite web|url=http://www51.honeywell.com/aero/technology/trends3/solutions3/obogs.html?c=13|title=On-Board Oxygen Generating System (OBOGS)|website=Honeywell.com|publisher=Honeywell International Inc.|archive-url=https://web.archive.org/web/20110910220215/http://www51.honeywell.com/aero/technology/trends3/solutions3/obogs.html?c=13|archive-date=10 September 2011|url-status=dead|access-date=9 Feb 2019}}</ref>
[[File:pressure swing adsorption principle.svg|thumb|left|link={{filepath:pressure_swing_adsorption_principle.svg}}|Animation of pressure swing adsorption, (1) and (2) showing alternating adsorption and desorption
{|
!I
|compressed air input
|rowspan="3" width="3em"|
!A
|adsorption
|-
!O
|oxygen output
!D
|desorption
|-
!E
|exhaust
|}]]

Zeolite-based [[oxygen concentrator]] systems are widely used to produce medical-grade oxygen. The zeolite is used as a [[molecular sieve]] to create purified oxygen from air using its ability to trap impurities, in a process involving the adsorption of nitrogen, leaving highly purified oxygen and up to 5% argon.

The German group [[Fraunhofer Society|Fraunhofer e.V.]] announced that they had developed a zeolite substance for use in the [[biogas]] industry for long-term storage of energy at a density four times greater than water.<ref>{{Cite web|url=http://www.fraunhofer.de/en/press/research-news/2012/june/compact-and-flexible-thermal-storage.html|title=Compact and flexible thermal storage|date=1 Jun 2012|website=Fraunhofer Research News|publisher=Fraunhofer-Gesellschaft}}</ref>{{Primary source inline|date=August 2021}}<ref>{{Cite journal |last1=Pirsaheb |first1=Meghdad |last2=Hossaini |first2=Hiwa |last3=Amini |first3=Jila |date=2021 |title=Operational parameters influenced on biogas production in zeolite/anaerobic baffled reactor for compost leachate treatment |journal=Journal of Environmental Health Science & Engineering |volume=19 |issue=2 |pages=1743–1751 |doi=10.1007/s40201-021-00729-3 |pmc=8617091 |pmid=34900303|bibcode=2021JEHSE..19.1743P }}</ref><ref>{{Cite journal |last1=Druzyanova |first1=Varvara |last2=Petrova |first2=Sofya |last3=Khiterkheeva |first3=Nadezhda |last4=Bardamova |first4=Irina |last5=Gergenova |first5=Tatyana |date=2020 |editor-last=Rudoy |editor-first=D. |editor2-last=Ignateva |editor2-first=S. |title=The use of zeolites for biogas purification in agricultural production |journal=E3S Web of Conferences |volume=175 |pages=12012 |doi=10.1051/e3sconf/202017512012|doi-access=free |bibcode=2020E3SWC.17512012D }}</ref> Ultimately, the goal is to store heat both in industrial installations and in small combined heat and power plants such as those used in larger residential buildings.

[[Debbie Meyer Green Bags]], a produce storage and preservation product, uses a form of zeolite as its active ingredient. The bags are lined with zeolite to adsorb [[ethylene]], which is intended to slow the ripening process and extend the shelf life of produce stored in the bags.

Clinoptilolite has also been added to chicken food: the absorption of water and ammonia by the zeolite made the birds' droppings drier and less odoriferous, hence easier to handle.<ref>{{Cite book|title=Innovative Biological Technologies for Lesser Developed Countries|vauthors=Mumpton FA|publisher=US Congress, Office of Technology Assessment|year=1985|veditors=Elfring C|location=Washington, DC|chapter=Ch. VIII. Using Zeolites in Agriculture|lccn=85600550|chapter-url=https://www.princeton.edu/~ota/disk2/1985/8512/851210.PDF |archive-url=https://ghostarchive.org/archive/20221010/https://www.princeton.edu/~ota/disk2/1985/8512/851210.PDF |archive-date=2022-10-10 |url-status=live}}</ref>

Zeolites are also used as a [[molecular sieve]] in [[cryopump|cryosorption]] style [[vacuum pump]]s.<ref>{{cite book|url=https://books.google.com/books?id=4kvzBRUuGDkC&pg=PA17|title=The Art of Cryogenics: Low-Temperature Experimental Techniques|vauthors=Ventura G, Risegari L|publisher=Elsevier|year=2007|isbn=9780080444796|pages=17}}</ref>

===Solar energy storage and use===
Zeolites can be used to thermochemically store solar heat harvested from [[solar thermal collector]]s as first demonstrated by Guerra in 1978<ref>U.S. Pat. No. 4,269,170, "Adsorption Solar Heating and Storage System", Filed April 27, 1978, Inventor: John M. Guerra</ref> and for [[adsorption refrigeration]], as first demonstrated by Tchernev in 1974.<ref>U.S. Patent No. 4,034,569, Filed November 4, 1974, Inventor: Dimiter I. Tchernev</ref> In these applications, their high heat of [[adsorption]] and ability to [[hydrate]] and dehydrate while maintaining structural stability is exploited. This [[hygroscopic]] property coupled with an inherent [[exothermic]] (energy releasing) reaction when transitioning from a dehydrated form to a hydrated form make natural zeolites useful in harvesting waste heat and solar heat energy.{{Primary source inline|date=August 2021}}

=== Building materials ===

Synthetic zeolites are used as an additive in the production process of warm mix [[asphalt concrete]]. The development of this application started in Germany in the 1990s. They help by decreasing the temperature level during manufacture and laying of asphalt concrete, resulting in lower consumption of fossil fuels, thus releasing less [[carbon dioxide]], aerosols, and vapors. The use of synthetic zeolites in hot mixed asphalt leads to easier compaction and, to a certain degree, allows cold weather paving and longer hauls.

When added to [[Portland cement]] as a [[pozzolan]], they can reduce chloride permeability and improve workability. They reduce weight and help moderate water content while allowing for slower drying, which improves break strength.<ref>{{cite conference|last=Dypayan J|year=2007|title=Clinoptilolite – a promising pozzolan in concrete|url=https://docs.wixstatic.com/ugd/df6185_396378e6da9840ba9de3cc2b39926a0e.pdf |archive-url=https://ghostarchive.org/archive/20221010/https://docs.wixstatic.com/ugd/df6185_396378e6da9840ba9de3cc2b39926a0e.pdf |archive-date=2022-10-10 |url-status=live|conference=29th ICMA Conference|location=Quebec City, Canada|publisher=Construction Materials Consultants, Inc.|pages=168–206|access-date=7 Oct 2013|book-title=A New Look at an Old Pozzolan}}</ref> When added to [[lime mortar]]s and lime-metakaolin mortars, synthetic zeolite pellets can act simultaneously as a pozzolanic material and a water reservoir.<ref name="air lime mortars">{{cite journal|display-authors=3|vauthors=Andrejkovičová S, Ferraz E, Velosa AL, Silva AS, Rocha F|year=2012|title=Air Lime Mortars with Incorporation of Sepiolite and Synthetic Zeolite Pellets|url=http://www.irsm.cas.cz/materialy/acta_content/2012_01/8_Andrejkovicova.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://www.irsm.cas.cz/materialy/acta_content/2012_01/8_Andrejkovicova.pdf |archive-date=2022-10-10 |url-status=live|journal=Acta Geodynamica et Geomaterialia|volume=9|issue=1|pages=79–91}}</ref><ref name="air lime-metakaolin mortars">{{cite journal|display-authors=3|vauthors=Ferraza E, Andrejkovičová S, Velosa AL, Silva AS, Rocha F|year=2014|title=Synthetic zeolite pellets incorporated to air lime–metakaolin mortars: mechanical properties|url=http://repositorio.lnec.pt:8080/jspui/handle/123456789/1006428|journal=Construction & Building Materials|volume=69|pages=243–252|doi=10.1016/j.conbuildmat.2014.07.030}}</ref>

=== Cat litter ===

Non-clumping [[cat litter]] is often made of zeolite (or [[diatomite]]), one form of which, invented at [[MIT]], can sequester the [[greenhouse gas]] [[methane]] from the atmosphere.<ref>{{Cite news|url=https://www.wsj.com/articles/cat-litter-could-be-antidote-for-climate-change-researchers-say-11652490018|title=Cat Litter Could Be Antidote for Climate Change, Researchers Say|first=Ryan|last=Dezember|newspaper=WSJ |date=May 14, 2022|via=www.wsj.com}}</ref>

=== Hemostatic agent ===

The original formulation of [[QuikClot]] brand [[Hemostatic agents|hemostatic agent]], which is used to stop severe bleeding,<ref>{{Cite journal|display-authors=3|vauthors=Rhee P, Brown C, Martin M, Salim A, Plurad D, Green D, Chambers L, Demetriades D, Velmahos G, Alam H|year=2008|title=QuikClot use in trauma for hemorrhage control: case series of 103 documented uses|journal=The Journal of Trauma and Acute Care Surgery|volume=64|issue=4|pages=1093–9|doi=10.1097/TA.0b013e31812f6dbc|pmid=18404080|s2cid=24827908}}</ref> contained zeolite granules. When in contact with blood, the granules would rapidly absorb water from the blood plasma, creating an exothermic reaction which generated heat. The absorption of water would also concentrate clotting factors present within the blood, causing the clot formation process to occur much faster than under normal circumstances, as shown [[in vitro]].<ref>{{Cite journal|display-authors=3 |last1=Li |first1=Jing |last2=Cao |first2=Wei |last3=Lv |first3=Xiao-xing |last4=Jiang |first4=Li |last5=Li |first5=Yue-jun |last6=Li |first6=Wang-zhou |last7=Chen |first7=Shao-zong |last8=Li |first8=Xue-yong |date=2013-03-01 |title=Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro |journal=Acta Pharmacologica Sinica |volume=34 |issue=3 |pages=367–372 |doi=10.1038/aps.2012.159 |issn=1671-4083 |pmc=4002488 |pmid=23334236}}</ref>

The 2022 formulation of QuikClot uses a nonwoven material impregnated with [[Kaolinite|kaolin]], an inorganic mineral activating [[Factor XII]], in turn accelerating natural clotting.<ref>{{Cite web |title=QuikClot for Military {{!}} US Dept of Defense Hemostatic Dressing of Choice |url=https://quikclot.com/EN/Products/Military|date=2022 |access-date=2023-10-01 |publisher=Teleflex Inc.}}</ref> Unlike the original zeolite formulation, [[Kaolinite|kaolin]] does not exhibit any thermogenic properties.

=== Soil treatment ===
{{ multiple image
| image1   = LIFE ZEOWINE 1.jpg
| caption1 = Mixing composted waste matter from wine production with zeolites
| image2   = LIFE ZEOWINE 2.jpg
| caption2 = The microporous structure of the zeolites put into ground stabilizes water release and pH
}}

In agriculture, [[clinoptilolite]] (a naturally occurring zeolite) is used as a soil treatment. It provides a source of slowly released [[potassium]]. If previously loaded with [[ammonium]], the zeolite can serve a similar function in the slow release of [[nitrogen]].

Zeolites can also act as water moderators, in which they will absorb up to 55% of their weight in water and slowly release it under the plant's demand. This property can prevent root rot and moderate drought cycles.

=== Aquaria ===

Pet stores market zeolites for use as filter additives in [[aquarium|aquaria]],<ref name="Virta-2011" /> where they can be used to adsorb [[ammonia]] and other nitrogenous compounds. Due to the high affinity of some zeolites for calcium, they may be less effective in hard water and may deplete calcium. Zeolite filtration is also used in some marine aquaria to keep nutrient concentrations low for the benefit of corals adapted to nutrient-depleted waters.

Where and how the zeolite was formed is an important consideration for aquarium applications. Most Northern hemisphere, natural zeolites were formed when molten lava came into contact with sea water, thereby "loading" the zeolite with Na (sodium) sacrificial ions. The mechanism is well known to chemists as [[ion exchange]]. These sodium ions can be replaced by other ions in solution, thus the take-up of nitrogen in ammonia, with the release of the sodium. A deposit near [[Bear River (Great Salt Lake)|Bear River]] in southern [[Idaho]] is a fresh water variety (Na < 0.05%).<ref>{{cite journal|display-authors=3|vauthors=Hongting Z, Vance GF, Ganjegunte GK, Urynowicz MA|date=2008|title=Use of zeolites for treating natural gas co-produced waters in Wyoming, USA|journal=Desalination|volume=228|issue=1–3|pages=263–276|doi=10.1016/j.desal.2007.08.014|bibcode=2008Desal.228..263Z }}</ref> Southern hemisphere zeolites are typically formed in freshwater and have a high calcium content.<ref>{{cite journal|last1=Wang|first1=Shaobin|last2=Peng|first2=Yuelian|url=http://ida-ore.com/wp-content/uploads/2020/02/Wang_Natural-zealots-as-effective-absorbents.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://ida-ore.com/wp-content/uploads/2020/02/Wang_Natural-zealots-as-effective-absorbents.pdf |archive-date=2022-10-10 |url-status=live|title=Natural zeolites as effective adsorbents in water & wastewater treatment|date=2009-10-09|journal=Chemical Engineering Journal|volume=156|issue=1|pages=11–24|doi=10.1016/j.cej.2009.10.029|access-date=2019-07-13}}</ref>

===Veterinary and human use===
Zeolites have some veterinary applications, with [[clinoptilolite]] approved in the EU as an additive for cattle feed.<ref>{{cite journal |title=Scientific Opinion on the safety and efficacy of clinoptilolite of sedimentary origin for all animal species: Clinoptilolite of sedimentary origin for all animal species |journal=EFSA Journal |date=January 2013 |volume=11 |issue=1 |pages=3039 |doi=10.2903/j.efsa.2013.3039}}</ref> It acts primarily as a detoxifying agent in the gut, where is can absorb undesirable species via ion-exchange before being excreted. For instance, nitrate fertilisers are water soluble and prolonged exposure by dairy cattle is known to impair protein metabolism and glucose utilization. Clinoptilolite adsorbs nitrate ions with good selectivity, allowing it to reduce these ill effects.<ref>{{cite journal |last1=Katsoulos |first1=P. D. |last2=Karatzia |first2=M. A. |last3=Polizopoulou |first3=Z. |last4=Florou-Paneri |first4=P. |last5=Karatzias |first5=H. |title=Effects of prolonged consumption of water with elevated nitrate levels on certain metabolic parameters of dairy cattle and use of clinoptilolite for their amelioration |journal=Environmental Science and Pollution Research |date=June 2015 |volume=22 |issue=12 |pages=9119–9126 |doi=10.1007/s11356-014-4060-8|pmid=25874417 |bibcode=2015ESPR...22.9119K }}</ref>

Zeolites have been studied for human medical applications,<ref>{{cite journal |last1=Kraljević Pavelić |first1=Sandra |last2=Simović Medica |first2=Jasmina |last3=Gumbarević |first3=Darko |last4=Filošević |first4=Ana |last5=Pržulj |first5=Nataša |last6=Pavelić |first6=Krešimir |title=Critical Review on Zeolite Clinoptilolite Safety and Medical Applications in vivo |journal=Frontiers in Pharmacology |date=27 November 2018 |volume=9 |page=1350 |doi=10.3389/fphar.2018.01350|doi-access=free |pmid=30538633 |pmc=6277462 }}</ref> particularly for bowel conditions.<ref>{{cite journal |last1=Mosgoeller |first1=Wilhelm |last2=Muss |first2=Claus |last3=Eisenwagen |first3=Sandra |last4=Jagsch |first4=Reinhold |last5=Vogelsang |first5=Harald |title=PMA – Zeolite (Clinoptilolite) in the Management of Irritable Bowel Syndrome – a Non-Interventional Study |journal=Zeitschrift für Gastroenterologie |date=March 2024 |volume=62 |issue=3 |pages=379–387 |doi=10.1055/a-2223-3963|pmid=38224685 |pmc=10914565 }}</ref><ref>{{cite journal |last1=Petkov |first1=V |last2=Schütz |first2=B |last3=Eisenwagen |first3=S |last4=Muss |first4=C |last5=Mosgoeller |first5=W |title=PMA-zeolite can modulate inflammation associated markers in irritable bowel disease - an explorative randomized, double blinded, controlled pilot trial. |journal=Neuro Endocrinology Letters |date=March 2021 |volume=42 |issue=1 |pages=1–12 |pmid=33930939}}</ref> There are no approved medical uses for zeolites as of 2024. Regardless, they are widely marketed as [[dietary supplements]].

== Mineral species ==
[[File:Stilbite-Ca-Natrolite-Laumontite-247898.jpg|thumb|A combination specimen of four zeolite species. The radiating natrolite crystals are protected in a pocket with associated stilbite. The matrix around and above the pocket is lined with small, pink-colored laumontite crystals. Heulandite is also present as a crystal cluster on the backside]]

The zeolite structural group ([[Nickel-Strunz classification]]) includes:<ref name="IZA-SC" /><ref name="Tschernich-1992" /><ref>{{Cite web|url=http://rruff.info/ima/|title=Database of Mineral Properties|publisher=[[International Mineralogical Association|IMA]]|access-date=9 Feb 2019}}</ref><ref>{{Cite web|url=https://www.mindat.org/strunz.php|title=Nickel-Strunz Classification - Primary Groups 10th ed|website=mindat.org|access-date=10 Feb 2019}}</ref><ref>{{Cite journal|display-authors=3|vauthors=First EL, Gounaris CE, Wei J, Floudas CA|year=2011|title=Computational characterization of zeolite porous networks: An automated approach|journal=[[Physical Chemistry Chemical Physics|Phys. Chem. Chem. Phys.]]|volume=13|issue=38|pages=17339–17358|doi=10.1039/C1CP21731C|pmid=21881655|bibcode=2011PCCP...1317339F}}</ref>

* 09.GA. – Zeolites with T<sub>5</sub>O<sub>10</sub> units (T = combined Si and Al): the fibrous zeolites
** Natrolite framework (NAT): [[gonnardite]], [[natrolite]], [[mesolite]], [[paranatrolite]], [[scolecite]], [[tetranatrolite]]
** Edingtonite framework (EDI): [[edingtonite]], [[kalborsite]]
** Thomsonite framework (THO): [[thomsonite]]-series
* 09.GB. – Chains of single connected 4-membered rings
** Analcime framework (ANA): [[analcime]], [[leucite]] ([[Topology|topologically]] a zeolite despite being [[anhydrous]]; chemically a [[feldspathoid]]),<ref>{{Cite web |title=Leucite |url=https://www.mindat.org/min-2465.html |access-date=2025-02-19 |website=www.mindat.org}}</ref> [[pollucite]], [[wairakite]]
** [[Laumontite]] (LAU), [[yugawaralite]] (YUG), [[goosecreekite]] (GOO), [[montesommaite]] (MON)
* 09.GC. – Chains of doubly connected 4-membered rings
** Phillipsite framework (PHI): [[harmotome]], [[phillipsite]]-series
** Gismondine framework (GIS): [[amicite]], [[gismondine]], [[garronite]], [[gobbinsite]]
** [[Boggsite]] (BOG), [[merlinoite]] (MER), [[mazzite]]-series (MAZ), [[paulingite]]-series (PAU), [[perlialite]] (Linde type L framework, zeolite L, LTL)
* 09.GD. – Chains of 6-membered rings: tabular zeolites
** Chabazite framework (CHA): [[chabazite]]-series, [[herschelite]], [[willhendersonite]] and [[SSZ-13]]
** Faujasite framework (FAU): [[faujasite]]-series, Linde type X (zeolite X, X zeolites), Linde type Y (zeolite Y, Y zeolites)
** Mordenite framework (MOR): [[maricopaite]], [[mordenite]]
** Offretite–wenkite subgroup 09.GD.25 (Nickel–Strunz, 10 ed): [[offretite]] (OFF), [[wenkite]] (WEN)
** [[Bellbergite]] (TMA-E, Aiello and Barrer; framework type EAB), [[bikitaite]] (BIK), [[erionite]]-series (ERI), [[ferrierite]] (FER), [[gmelinite]] (GME), [[levyne]]-series (LEV), [[dachiardite]]-series (DAC), [[epistilbite]] (EPI)
* 09.GE. – Chains of T<sub>10</sub>O<sub>20</sub> tetrahedra (T = combined Si and Al)
** Heulandite framework (HEU): [[clinoptilolite]], [[heulandite]]-series
** Stilbite framework (STI): [[barrerite]], [[stellerite]], [[stilbite]]-series
** Brewsterite framework (BRE): [[brewsterite]]-series
* Others
** [[Cowlesite]], [[pentasil]] (also known as [[ZSM-5]], framework type MFI), [[tschernichite]] (beta polymorph A, disordered framework, BEA), Linde type A framework (zeolite A, LTA)

== Computational study ==

Computer calculations have predicted that millions of hypothetical zeolite structures are possible. However, only 232 of these structures have been discovered and synthesized so far, so many zeolite scientists question why only this small fraction of possibilities are observed. This problem is often referred to as "the bottleneck problem".{{Citation needed|date=August 2021}} Currently, several theories attempt to explain the reasoning behind this question.

# Zeolite synthesis research has primarily concentrated on hydrothermal methods; however, new zeolites may be synthesized using alternative methods. Synthesis methods that have started to gain use include microwave-assisted, post-synthetic modification, and steam. 
# Geometric computer simulations have shown that the discovered zeolite frameworks possess a behavior known as "the flexibility window". This shows that there is a range in which the zeolite structure is "flexible" and can be compressed but retains the framework structure. It is suggested that if a framework does not possess this property then it cannot be feasibly synthesized.
# As zeolites are metastable, certain frameworks may be inaccessible as nucleation cannot occur because more stable and energetically favorable zeolites will form. Post-synthetic modification has been used to combat this issue with the ADOR method,<ref>{{Cite journal|display-authors=3|vauthors=Roth WJ, Nachtigall P, Morris RE, Wheatley PS, Seymour VR, Ashbrook SE, Chlubná P, Grajciar L, Položij M|date=2013|title=A family of zeolites with controlled pore size prepared using a top-down method|journal=[[Nature Chemistry|Nat. Chem.]]|volume=5|issue=7|pages=628–633|doi=10.1038/nchem.1662|pmid=23787755|bibcode=2013NatCh...5..628R|issn=1755-4330|hdl=10023/4529|hdl-access=free}}</ref> whereby frameworks can be cut apart into layers and bonded back together by either removing silica bonds or including them.
# Based on dense crystal model systems, the theory of crystallization via solute pre-nucleation clusters was developed.<ref>{{cite journal |last1=Gebauer |first1=Denis |last2=Kellermeier |first2=Matthias |last3=Gale |first3=Julian D. |last4=Bergström |first4=Lennart |last5=Cölfen |first5=Helmut |title=Pre-nucleation clusters as solute precursors in crystallisation |journal=Chemical Society Reviews |date=January 23, 2014 |volume=43 |issue=7 |pages=2348–2371 |doi=10.1039/C3CS60451A |pmid=24457316 |doi-access=free |hdl=20.500.11937/6133 |hdl-access=free }}</ref> Investigation of zeolite crystallization in hydrated silicate ionic liquids (HSIL) has shown that zeolites can nucleate via the condensation of ion-paired pre-nucleation clusters.<ref>{{cite journal |last1=Pellens |first1=Nick |last2=Doppelhammer |first2=Nikolaus |last3=Radhakrishnan |first3=Sambhu |last4=Asselman |first4=Karel |last5=Chandran |first5=C. Vinod |last6=Vandenabeele |first6=Dries |last7=Jakoby |first7=Bernhard |last8=Martens |first8=Johan A. |last9=Taulelle |first9=Francis |last10=Reichel |first10=Erwin K. |last11=Breynaert |first11=Eric |last12=Kirschhock |first12=Christine E.A. |title=Nucleation of Porous Crystals from Ion-Paired Prenucleation Clusters |journal=Chemistry of Materials |year=2022 |volume=34 |issue=16 |pages=7139–7149 |doi=10.1021/acs.chemmater.2c00418 |pmid=36032557 |pmc=9404542 }}</ref> This line of research identified several connections between the synthesis medium liquid chemistry and important properties of zeolite crystals, such as the role of inorganic structure-directing agents in zeolite framework selection,<ref>{{cite journal |last1=Asselman |first1=Karel |last2=Pellens |first2=Nick |last3=Radhakrishnan |first3=Sambhu |last4=Chandran |first4=C. Vinod |last5=Martens |first5=Johan A. |last6=Taulelle |first6=Francis |last7=Verstraelen |first7=Toon |last8=Hellström |first8=Matti |last9=Breynaert |first9=Eric |last10=Kirschhock |first10=Christine E.A. |title=Super-ions of sodium cations with hydrated hydroxide anions: inorganic structure-directing agents in zeolite synthesis |journal=Materials Horizons |date=August 4, 2021 |volume=8 |issue=9 |pages=2576–2583 |doi=10.1039/D1MH00733E |pmid=34870303 |hdl=1854/LU-8740859 |s2cid=238722345 |url=https://pubs.rsc.org/en/content/articlelanding/2021/mh/d1mh00733e/|hdl-access=free }}</ref> the role of ion-pairing on the zeolite molecular composition and topology,<ref>{{cite journal |last1=Asselman |first1=Karel |last2=Pellens |first2=Nick |last3=Thijs |first3=Barbara |last4=Doppelhammer |first4=Nikolaus |last5=Haouas |first5=Mohamed |last6=Taulelle |first6=Francis |last7=Martens |first7=Johan A. |last8=Breynaert |first8=Eric |last9=Kirschhock |first9=Christine E.A. |title=Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminium Content and Topology of Crystallizing Zeolites |journal=Chemistry of Materials |year=2022 |volume=34 |issue=16 |pages=7150–7158 |doi=10.1021/acs.chemmater.2c00773 |pmid=36032556 |pmc=9404546 }}</ref> and the role of liquid cation mobility on the zeolite crystal size and morphology.<ref>{{cite journal |last1=Pellens |first1=Nick |last2=Doppelhammer |first2=Nikolaus |last3=Thijs |first3=Barbara |last4=Jakoby |first4=Bernhard |last5=Reichel |first5=Erwin K. |last6=Taulelle |first6=Francis |last7=Martens |first7=Johan A. |last8=Breynaert |first8=Eric |last9=Kirschhock |first9=Christine E.A. |title=A zeolite crystallisation model confirmed by in situ observation |journal=Faraday Discussions |year=2022 |volume=235 |pages=162–182 |doi=10.1039/D1FD00093D|pmid=35660805 |bibcode=2022FaDi..235..162P |s2cid=245465624 |url=https://lirias.kuleuven.be/handle/20.500.12942/694201 }}</ref> Consequently, complex relations exist between the properties of zeolite synthesis media and the crystallizing zeolite, potentially explaining why only a small fraction of the hypothetical zeolite frameworks can be synthesized. While these relations are not yet fully understood, HSIL zeolite synthesis is an exceptional model system for zeolite science, providing opportunities to advance current understanding of the zeolite conundrum.

== See also ==

* {{annotated link|Geopolymer}}
* {{annotated link|List of minerals}}
* {{annotated link|Hypothetical zeolite}}
* {{annotated link|Adsorption}}
* {{annotated link|Solid sorbents for carbon capture}}
* {{annotated link|Pyrolysis}}

== References ==

{{refs}}

== Further reading ==

* The classic reference for the field has been Breck's book ''Zeolite Molecular Sieves: Structure, Chemistry, And Use''.<ref>{{Cite book|url=https://books.google.com/books?id=aY0vAQAAIAAJ|title=Zeolite molecular sieves: structure, chemistry, and use|last=Breck|first=Donald W.|date=1973|publisher=Wiley|isbn=9780471099857|language=en|name-list-style=vanc}}</ref>
* {{Cite book|title=United States mineral resources<!--DOI is for entire book, not this chapter FYI - do not change-->| vauthors=Sheppard RA |publisher=[[USGS]] |year=1973 |veditors=Brobst DA, Pratt WP |series=Professional Paper |volume=820 |location=Washington, DC |chapter=Zeolites in Sedimentary Rocks <!--DOI is for entire book, not this chapter FYI - do not change-->|doi=10.3133/pp820|pages=689–695}}
* {{Cite book|title=Natural and Synthetic Zeolites|vauthors=Clifton RA|publisher=[[United States Bureau of Mines|USBM]]|year=1987|series=Information Circular, 9140|location=Pittsburgh|oclc=14932428}}
* {{Cite journal|title=La roca magica: Uses of natural zeolites in agriculture and industry|journal=[[Proceedings of the National Academy of Sciences of the United States of America|PNAS]]|volume=96|issue=7|pages=3463–3470|vauthors=Mumpton FA|year=1999|doi=10.1073/pnas.96.7.3463|pmid=10097058|pmc=34179|bibcode=1999PNAS...96.3463M|doi-access=free}}
* {{Cite journal|vauthors=Monnier JB, Dupont M|date=1983|title=Zeolite-water close cycle solar refrigeration; numerical optimisation and field-testing|journal=[[International Solar Energy Society|Proc. Annu. Meet. - Am. Sect. Int. Sol. Energy Soc.]]|volume=6|pages=181–185|osti=5126636}} [[American Solar Energy Society|American Solar Energy Society meeting]]. 1 Jun 1983. Minneapolis, MN, USA
* {{Cite book|vauthors=Newsam JM|title=Solid State Chemistry|publisher=Clarendon Press|year=1992|isbn=9780198551669|veditors=Cheetham AK, Day P|volume=2|chapter=Zeolites}}
* {{cite journal|vauthors=Rhodes CJ|year=2007|title=Zeolites: Physical Aspects and Environmental Applications|journal=[[Annual Reports on the Progress of Chemistry, Section C|Annu. Rep. Prog. Chem. C]]|volume=103|pages=287–325|doi=10.1039/b605702k}}
* {{USGS|title=Zeolites|url=http://minerals.usgs.gov/minerals/pubs/commodity/zeolites/myb1-2009-zeoli.pdf}}

== External links ==
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* [http://www.iza-online.org/ International Zeolite Association]
* [http://helios.princeton.edu/zeomics/ Database of zeolite pore characterizations] {{Webarchive|url=https://web.archive.org/web/20140524081408/http://helios.princeton.edu/zeomics/ |date=2014-05-24 }}
* [https://web.archive.org/web/20050911080247/http://www.iza-synthesis.org:80/ The Synthesis Commission of the International Zeolite Association]
* [http://www.feza-online.eu/ Federation of European Zeolite Associations]
* [http://www.bza.org/ British Zeolite Association]
* [http://www.iza-structure.org/databases/ Database of Zeolite Structures]
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[[Category:Zeolites]]
[[Category:Tectosilicates]]
[[Category:Antihemorrhagics]]
[[Category:Conservation and restoration materials]]
[[Category:Porous media]]
[[Category:Industrial minerals]]
[[Category:Catalysts]]
[[Category:Acid catalysts]]