Zeolites in Catalysis

Properties and Applications

Jiří ejka, Russell E Morris, Petr Nachtigall

• Publisher: Royal Society of Chemistry
• Year: 2017
• Print ISBN:
  9781782627845
• eBook ISBN:
  9781788011563
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

Covering the breadth of zeolite chemistry and catalysis, this book provides the reader with a complete introduction to field, covering synthesis, structure, characterisation and applications.

Beginning with the history of natural and synthetic zeolites, the reader will learn how zeolite structures are formed, synthetic routes, and experimental and theoretical structure determination techniques. Their industrial applications are covered in-depth, from their use in the petrochemical industry, through to fine chemicals and more specialised clinical applications. Novel zeolite materials are covered, including hierarchical zeolites and two-dimensional zeolites, showcasing modern developments in the field. This book is ideal for newcomers who need to get up to speed with zeolite chemistry, and also experienced researchers who will find this a modern, up-to-date guide.

CHAPTER 1

Zeolite Science and Perspectives

R. MILLINI* AND G. BELLUSSI

Eni S.p.A., Research & Technological Innovation Dept., R&D Program Energy Transition, Via F. Maritano 26, I-20097 San Donato Milanese, Italy
*Email: [email protected]

1.1 Historical Background

The history of zeolites began in 1756, when the Swedish mineralogist Axel F. Cronstedt described the particular properties of minerals found in a copper mine in Svappavari (Lapland, Sweden) and in an unidentified locality in Iceland: when the minerals were heated in a blow-pipe flame, they seemed to boil. For this particular property, not found in other minerals known at that time, Cronstedt coined the term zeolite (from the Greek ζέω = to boil and λíθος = stone).¹ In 1772 Ignaz von Born used this term to describe cubic crystals found in Iceland (Zeolithus crystallisatus cubicus Islandiae), later defined a zeolite en cube by Jean-Baptiste Louis de Romé l’Isle (1783) and chabasie by Louis Augustin Guillaume Bosc d’Antic (1788); today it is known as chabazite. During the nineteenth century, several authors reported the discovery of new minerals classified as zeolites as well as the description of some of their basic properties. For instance, in 1857 A. Damour observed that crystals of different natural zeolites (harmotome, brewsterite, faujasite, chabazite, gmelinite, analcime, levyne) desorb water, without any apparent change of transparency and morphology.² In 1896 G. Friedel examined in detail the reversible dehydration of analcime, concluding that water molecules are simply included and not chemically bonded to the aluminosilicate crystal;³ he also reported that zeolites (chabazite, harmotome, heulandite, and analcime), once dehydrated, abundantly absorb gaseous ammonia, carbon dioxide, hydrogen sulfide, as well as alcohol, chloroform, and benzene.⁴ Later on, F. Grandjean showed that dehydrated chabazite adsorbs ammonia, air, mercury, sulfur, and other species,⁵ behavior later confirmed by R. Seeliger and K. Lapkamp.⁶ In 1925, O. Weigel and E. Steinhoff reported the adsorption behavior of dehydrated chabazite, which readily adsorbs water, methanol, ethanol, and formic acid, but not diethyl ether, acetone, and benzene.⁷ This fundamental property of zeolites was studied in detail by J. W. McBain, who coined the term “molecular sieve”.⁸ Some years later, R. M. Barrer and D. A. Ibbitson found that linear alkanes (propane, n-butane, n-pentane, and n-heptane) were rapidly adsorbed on chabazite at temperatures >373 K, while branched isomers (e.g. i-butane and i-octane) were totally excluded.⁹ Based on these and other observations on the adsorption behavior, R. M. Barrer classified zeolites into three groups.¹⁰

Following the discovery that soils undergo ion-exchange when contacted with solutions of ammonium salts¹¹ and that ammonium or potassium are exchanged for calcium,¹² in 1858 H. Eichhorn first reported that this phenomenon reversibly occurs also in natrolite and chabazite.¹³

A major boost to the studies of zeolites occurred in 1930 with the first resolution of the crystal structure of a zeolite, analcite (analcime), by W. H. Taylor¹⁴ followed by those of natrolite, davynite-cancrinite,¹⁵ and sodalite¹⁶ by L. Pauling. This allowed the following main characteristics of these materials to be defined:

1. a tridimensional framework built up of corner-sharing [SiO₄] and [AlO₄] tetrahedra;
2. the presence of regular channels and/or cages (known as micropores) with free dimensions that vary from one zeolite to another but are generally in the range 3–12 Å;
3. the negative framework charge, due to the presence of [AlO₄] tetrahedra, is compensated by alkali (Na, K, …) and/or earth-alkali (Mg, Ca, …) cations located in the micropores; they are loosely bound to the framework and easily exchangeable by other cations;
4. the presence of water molecules in the micropores, which can be reversibly desorbed upon mild thermal treatment;
5. the following chemical composition:
   (M⁺)_a(M²⁺)_b[Al_{(a + 2b)}Si_{n−(a + 2b)}O_2n] · mH₂O
   The atomic ratio O/(Si + Al) = 2 is typical of the class of the tectosilicates, to which zeolites belong, while according to the Lowenstein’s rule,¹⁷ the Si/Al ratio is always ≥1.

Gathering all these findings together, in 1930 M. H. Hey wrote the first general review on zeolites, highlighting the critical issues still to be clarified.¹⁸ Only in 1963, J. V. Smith proposed the first definition of zeolite, as “an aluminosilicate with a framework structure enclosing cavities occupied by large ions and water molecules, both of which have considerable freedom of movement, permitting ion-exchange and reversible dehydration”.¹⁹

1.2 Natural Zeolites

Until the 1940s, zeolites were considered minerals without any practical interest, almost exclusively studied by mineralogists, who were more interested in understanding the environments and the crystallization conditions of these phases than in their practical uses. In this period, the discovery of new zeolites concerned mainly minerals of hydrothermal origin, consisting of very large (even cm-sized) crystals occurring as minor constituents in cracks or cavities in basaltic and volcanic rocks. Generally, they are found in the form of large crystals of different morphology and color, often in association with different zeolite phases and other minerals. The latest update on natural hydrothermal zeolites lists 67 different species.²⁰ Among them, it is interesting to examine the minerals discovered in the 30 years prior to 2013 (Table 1.1).

Table 1.1 Zeolite minerals discovered since 1983²⁰ (non-aluminosilicate phases in bold; the three-letter codes highlighted in italics denote mineral phases with already known synthetic counterparts).

Name	Year	Formula	Framework type
Alflarsenite	2009	[NaCa2(H2O)2][Be3Si4O13(OH)]	—
Ammonioleucite	1986	[(NH4,K)][AlSi2O6]	ANA
Bellbergite	1993	[(K,Ba,Sr)2Sr2Ca2(Ca,Na)4(H2O)30][Al18Si18O72]	EAB
Boggsite	1990	[(Ca,Na0.5,K0.5)9(H2O)70][Al18Si78O192]	BOG
Chiavennite	1983	[CaMn(H2O)2][Be2Si5O13(OH)2]^a	-CHI
Direnzoite	2008	[NaK6MgCa2(H2O)36][Al13Si47O120]	EON
Flörkeite	2009	[K3Ca2(H2O)12][Al8Si8O32]	PHI
Gaultite	1994	[Na4(H2O)5][Zn2Si7O18]	VSV
Gottardiite	1996	[(Na,K)Mg3Ca5(H2O)95][Al19Si117O272]	NES
Kirchhoffite	2012	[Cs][B2Si4O10]	—
Maricopaite	1988	[(Pb,Ca)2(H2O,OH)32][Al12Si36(O,OH)100]^a	MOR
Montesommaite	1990	[K9(H2O)10][Al9Si23O64]	MON
Mutinaite	1997	[Na3Ca4(H2O)60][Al11Si85O192]	MFI
Nabesite	1992	[Na2(H2O)4][BeSi4O10]	NAB
Pahasapaite	1987	[(Ca5.5Li5.6K1.2Na0.2)Li8(H2O)38][Be24P24O96]	RHO
Terranovaite	1997	[NaCa(H2O)13][Al3Si17O40]	TER
Tschernichite	1993	[(Ca,Mg,Na0.5)(H2O)8][Al2Si6O16]	Beta
Tschörtnerite	1998	[Ca4(K2,Ca,Sr,Ba)3Cu3(OH)8(H2O)20][Al12Si12O48]	TSC
Tvedalite	1992	[(Ca,Mn)4(H2O)3][Be3Si6O17(OH)4]	—
Weinebeneite	1992	[Ca(H2O)4][Be3P2O8(OH)2]	WEI

^a Interrupted framework.

According to the definition proposed by J. V. Smith, it is clear that some of these minerals:

1. are not aluminosilicates, but contain Be or Zn instead of Al (e.g. Chiavennite, Gaultite, Nabesite) or are beryllophosphates (Pahasapaite, Weinebeneite);
2. do possess an interrupted framework (e.g. Chiavennite, Maricopaite);
3. are anhydrous (e.g. Ammonioleucite)

In 1993, a subcommittee of the Commission on New Minerals and Mineral Names of the International Mineralogical Association started a long and detailed work in defining an appropriate nomenclature of zeolites. Considering the above reported violations of Smith’s definition, in 1997 it defined a zeolite mineral as:

“… a crystalline substance with a structure characterized by a framework of linked tetrahedra, each consisting of four O atoms surrounding a cation. This framework contains open cavities in the form of channels and cages. These are usually occupied by H₂O molecules and extra-framework cations that are commonly exchangeable. The channels are large enough to allow the passage of guest species. In the hydrated phases, dehydration occurs at temperature mostly below about 400 °C and is largely reversible. The framework may be interrupted by (OH,F) groups; these occupy a tetrahedron apex that is not shared with adjacent tetrahedra”.²¹

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Table of contents

• Cover
• Title
• Copyright
• Preface
• Contents
• Chapter 1 Zeolite Science and Perspectives
• Chapter 2 Zeolite Structures
• Chapter 3 Synthesis of Zeolites
• Chapter 4 Hierarchical Zeolites
• Chapter 5 Two-dimensional Zeolites
• Chapter 6 Structure Determination
• Chapter 7 Spectroscopy of Zeolites
• Chapter 8 Electron Microscopy of Zeolites
• Chapter 9 Zeolites in Industrial Catalysis
• Chapter 10 Application of Zeolites in the Production of Light Olefins and BTX Petrochemical Intermediates
• Chapter 11 Zeolites for Fine Chemistry
• Chapter 12 Biomass Conversion over Zeolite Catalysts
• Chapter 13 Zeolite Membranes in Catalysis
• Subject Index