Table Of ContentCatalysis and Zeolites
Springer-Verlag Berlin Heidelberg GmbH
J. Weitkamp · L. Puppe (Eds.)
Catalysis and Zeolites
Fundamentals and Applications
With 211 Figures and 48 Tables
, Springer
Prof Dr.-lng. lens Weitkamp
UniversWit Stuttgart
Institut fur Technische Chemie I
D-70SS0 Stuttgart
Germany
Dr. Lothar Puppe
Bayer AG
Geschaftsbereich Chemikalien
CH -F-FC, Gebaude G 8
D-S1368 Leverkusen
Germany
ISBN 978-3-642-08347-1
Library of Congress Cataloging-in-Publication Data
Catalysis and zeolites: fundamentals and applications / J. Weitkamp, L. Puppe (eds.).
includes bibliographical references and index.
ISBN 978-3-642-08347-1 ISBN 978-3-662-03764-5 (eBook)
DOI 10.1007/978-3-662-03764-5
1. Zeolites. 2. Catalysis. I. Weitkamp, J. (Jens) II. Puppe, L. (Lothar)
TP245.S5 C39 199 660'.2995-dc21 98-48578
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Preface
Zeolites occur in nature and have been known for almost 250 years as alumino
silicate minerals. Examples are clinoptilolite, mordenite, offretite, ferrierite,
erionite and chabazite. Today, most of these and many other zeolites are of great
interest in heterogeneous catalysis, yet their naturally occurring forms are of
limited value as catalysts because nature has not optimized their properties for
catalytic applications and the naturally occurring zeolites almost always contain
undesired impurity phases.
It was only with the advent of synthetic zeolites in the period from about 1948
to 1959 (thanks to the pioneering work of R.M. Barrer and R. M. Milton) that this
class of porous materials began to playa role in catalysis. A landmark event was
the introduction of synthetic faujasites (zeolite X at first, zeolite Y slightly later)
as catalysts in fluid catalytic cracking (FCC) of heavy petroleum distillates in
1962, one of the most important chemical processes with a worldwide capacity
of the order of 500 million t/a. Compared to the previously used amorphous
silica-alumina catalysts, the zeolites were not only orders of magnitude more
active, which enabled drastic process engineering improvements to be made, but
they also brought about a significant increase in the yield of the target product,
viz. motor gasoline. With the huge FCC capacity worldwide, the added value
of this yield enhancement is of the order of 10 billion US $ per year. No wonder
therefore, that the introduction of zeolitic FCC catalysts is often referred to as a
true revolution in petroleum refining.
Given this enormous success, it is not surprising that, in the period after
1962, zeolite catalysts rapidly conquered additional processes, at first in the field
of petroleum refining, somewhat later in the field of basic petrochemistry. Exam
pIes of industrial processes (besides FCC) where zeolite catalysts nowadays have
a firm place are hydrocracking of heavy petroleum distillates, octane number
enhancement of light gasoline by isomerization, dewaxing of heavy petroleum
distillates and lubricating oils, the synthesis of ethylbenzene (the precursor
chemical of styrene and polystyrene) from benzene and ethene, the isomeriza
tion of xylenes (to produce para-xylene, the precursor chemical for terephthalic
acid and polyesters derived from it) and the disproportionation of toluene into
benzene and xylenes. Today, catalysis is the single most important application of
zeolites in terms of financial market size (not in terms of tons produced per year)
with an estimated turnover in the order of 1 billion US $ per year worldwide.
In these more traditional fields, zeolite catalysis has without doubt reached a
certain degree of maturity. However, new applications for zeolites as catalysts are
VI Preface
emerging, especially in the broad area of manufacturing organic intermediates
and fine chemicals. In addition, the potential of zeolite catalysts for the purifica
tion of exhaust gases, e. g., from diesel engines, is under intense scrutiny all over
the world. Here, the environmental aspect of zeolite catalysis becomes obvious,
yet the search for zeolitic catalysts in organic syntheses is often driven by
environmental aspects as well, especially if less benign catalyst systems like
hydrofluoric acid, aluminum trichloride etc. are to be replaced by zeolites.
Altogether, zeolite catalysis has become a most important sub-field of hetero
geneous catalysis. Nobody who is active in heterogeneous catalysis, either in
industry or at a research institution, can afford to ignore zeolites and the
remarkable progress that is still being made in their synthesis, post-synthesis
modification, pysico-chemical characterization and testing.
This book therefore starts, in Chapter 1 written by J.-L. Guth and H. Kessler,
with a state-of-the-art review of the synthesis methods for alumino silicate
zeolites and related silica-based materials. The term "zeolite" is nowadays used
in a much broader sense than the one traditionally used by mineralogists, and
it encompasses numerous zeolite-like, cristalline microporous solids with ele
ments other than silicon and aluminum on tetrahedral framework positions.
Many of these materials do have a potential as catalysts, and the most important
family of such materials, the aluminophosphates and their derivatives, are dealt
with in Chapter 2 by J.A. Martens and P.A. Jacobs. An overview of the available
post-synthesis techniques for the transformation of a zeolite with the desired
framework into a catalyst with optimal acidic, shape-selective etc. properties
is given in Chapter 3 written by G. Kahl. An in-depth treatment of the most
relevant techniques for zeolite characterization, viz. X-ray powder diffraction,
infrared spectroscopy and nuclear magnetic resonance spectroscopy, has been
contributed by H. G. Karge, M. Hunger, and H. K. Beyer in the central Chapter 4.
Chapter 5, written by J. Weitkamp, S. Ernst, and L. Puppe, deals with the prin
ciples and fundamentals of shape-selective catalysis which is unique for cata
lysts with pore widths in the order of molecular dimensions. A critical review of
the recent literature on the use of zeolite catalysts in organic chemistry is pre
sented in Chapter 6 by P. Espeel, R. Parton, H. Youfar, J. A. Martens, W. Holderich,
and P.A. Jacobs. The final Chapter 7 by P.M.M. Blauwhoff, J. w. Gosselink, E.P.
Kieffer, S. T. Sie, and W.H.J. Stork discusses the industrial processes which are
currently in operation using zeolitic catalysts and the specific effects of the
zeolites in those processes. The editors sincerely thank the authors for having
contributed to this book and for having devoted a large amount of their precious
time to the respective chapters.
Catalysis and Zeolites is meant to provide comprehensive and valuable in
formation to all those who already are working in the field or who plan to use
zeolites as catalysts in their future research. It is our hope that the book will fully
meet the readers' expectations.
Jens Weitkamp April 1999
Lothar Puppe
Contents
1 Synthesis of Aluminosilicate Zeolites
and Related Silica-Based Materials
Jean-Louis Guth and Henri Kessler
1.1 Scope ..................... . 1
1.2 Introduction ....... . .... . . . . . . 1
1.2.1 Structure, Composition, Nomenclature ........ .. . 1
1.2.2 History of Zeolite Synthesis ................ . 4
1.3 Theoretical Part ....................... . 5
1.3.1 Crystallogenesis ...... . . . . . . . . . . . . . . . . . . 5
1.3.1.1 Nucleation ........................ . 5
1.3.1.2 Crystal Growth ...................... . 9
1.3.1.3 Advancement of the Crystallization with Time . . . . . 13
1.3.1.4 Ostwald's Rule ........... . . . . . . . . . . . . 14
1.3.2 Zeolite Synthesis, Mechanism and Chemistry . . . . . . . . . . . 16
1.3.2.1 Presentation of the Synthesis System .............. . 16
1.3.2.2 Framework T Elements .. . . . . . . . . . . . . . . . . . . . .. 18
1.3.2.3 Mineralizer and T Element Species in the Solution . . . . . . . . 20
1.3.2.4 Templates .............................. . 22
1.4 Experimental Part . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.4.1 Experimental Factors ...................... . 23
1.4.1.1 Nature of the Reactants . . . . . . . . . . . . . . . . . . . .. . 24
1.4.1.2 Composition of the Reaction Mixture . . . . . . . . . . . . . . 25
1.4.1.3 Preparation Procedure of the Reaction Mixture ........ . 25
1.4.1.4 Aging ............................ .... . 26
1.4.1.5 Seeding. . . . . . . . . . . . . . . . . . . . .... . . 26
1.4.1.6 Nature of the Reactor ... . . . . . . . . . . . . . . . . . . . 26
1.4.1.7 Crystallization Temperature ................... . 27
1.4.1.8 Pressure ..... ....... ... ..... .......... . 27
1.4.1.9 Agitation .............................. . 27
1.4.1.10 Heating Time ........................... . 27
1.4.2 Review of Zeolites Obtained from Various Reaction Systems .. 28
1.4.2.1 All-Silica Molecular Sieves (T = Si) ............... . 28
1.4.2.2 (Si, AI) Systems with Inorganic Cations ............. . 28
1.4.2.3 (Si,Al) Systems with Inorganic and Organic Templates . . .. . 29
VIII Contents
1.4.2.4 (Si,AI) Systems with Organic Templates 29
1.4.2.5 (Si, Til) Systems, Til = Be, Co, Cu, Zn 30
=
1.4.2.6 (Si, TIll) Systems, TIll B, Fe, Ga . . . . 31
=
1.4.2.7 (Si, TIV) Systems, TIV Ge, Ti, Zr . . . . 32
1.4.2.8 Other Si-Based Systems - V, Cr and Mo in Tetrahedral
Frameworks . . .. . .. . .. . .. . .. . . . 32
1.4.3 Synthesis of Some Selected Important Zeolites . . 33
1.4.3.1 Zeolites with the LTA-Type Structure . . . . ... 33
1.4.3.2 Zeolites with FAU-Type Structures and Polytypes 34
1.4.3.3 Synthesis of Zeolite Beta .. .. .. . .. .. . . . 36
1.4.3.4 Synthesis of Zeolite LTL . . . . . . . . . . . . . . . 37
1.4.3.5 Synthesis of Zeolites with the MAZ-Type Structure 37
1.4.3.6 Synthesis of Zeolites with the MFI -Type Structure . 38
1.4.3.7 Synthesis of Zeolites with the MOR-Type Structure 41
1.4.3.8 Synthesis of Zeolites with the OFF-and/or
the ERI-Type Structure . ... . .. .... . ... . 42
1.5 Synthesis of Other Selected Materials ..... .. . 44
1.5.1 Titanosilicates with Mixed Octahedral-Tetrahedral Frameworks 44
1.5.2 Synthesis of Mesoporous Aluminosilicates 45
1.6 Activation of Zeolites 46
References .. . . .. ... ... ... .. . 46
2 Phosphate-Based Zeolites and Molecular Sieves 53
Johan A. Martens and Pierre A. Jacobs
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
2.2 Structural, Synthetic and Physicochemical Concepts Relevant
to Poro-tecto-phosphates . ... . . 54
2.2.1 AIP04 (GaP04) Topological Concept . . ... . 54
2.2.2 Al (Ga) Coordination Concept .. . ... . . . 56
2.2.3 Template: Framework Stoichiometry Concept 60
2.3 Rationalization of Properties of Poro-tecto-phosphates
with Structural, Synthetic and Physicochemical Concepts 62
2.3.1 Pore Size ... . . . . . 62
2.3.2 Thermal Stability . . . . 62
2.3.3 Adsorption Properties 65
2.3.4 Isomorphic Substitution 68
2.3.5 Isomorphic Substitutions SM la, Ib and IIa Generating
Framework Charges . . . . . . . . . . . . . . . . . . . . 71
2.3.6 Isomorphic Substitutions Ic and IIb Generating Electroneutral
Frameworks .. ..... .. ... . . . ...... . 73
2.3.7 Si Incorporation According to SM III Generating Si
and AlP Domains .. . . .. ..... . .. . . . . . 74
2.3.8 Si Incorporation According to Combinations of SM II a
and SM III Generating SiAl and SiAlP Domains 75
References . . .. .. .. .. ....... . ..... . . 76
Contents IX
3 Modification of Zeolites 81
GUnter H. KUhl
3.1 Ion Exchange of Zeolites 81
3.1.1 Introduction and Theory 81
3.1.2 Aqueous Ion Exchange 81
3.1.2.1 Ion-Exchange Isotherms 84
3.1.2.2 Experimental . . . . . . . 86
3.1.2.3 Thermochemistry of Ion Exchange 88
3.l.3 Ion Exchange of Zeolites X and Y 88
3.l.3.1 Univalent Ion Exchange 90
3.l.3.2 Divalent Ion Exchange 93
3.l.3.3 Trivalent Ion Exchange 98
3.1.4 Ion Exchange of ZSM-5 100
3.1.4.1 Univalent Ion Exchange 100
3.1.4.2 Divalent Ion Exchange 102
3.1.4.3 Trivalent Ion Exchange 103
3.1.4.4 Aluminum-Independent Ion Exchange 103
3.2 Metals Supported on Zeolites . . . . 104
3.2.1 Reduction of Metal Ions in Zeolites 105
3.2.1.1 Group IB . . .... . .. . . 105
3.2.1.2 Group VIllA, Fourth Period 113
3.2.l.3 Group VIllA, Fifth Period . 116
3.2.1.4 Group VIllA, Sixth Period 123
3.3 Dealumination of Zeolites 127
3.3.1 Thermal Treatment 127
3.3.1.1 Hydrogen Zeolites . . . . . 128
3.3.1.2 Dehydroxylation . . . . . . l32
3.3.2 Extraction of Framework Aluminum with Acid l33
3.3.2.1 The Aluminum-Deficient Form . . .. . .. . . 134
3.3.2.2 Annealing of Tetrahedral Vacancies; High-Silica Faujasite l35
3.3.3 Hydrothermal Treatment l36
3.3.3.1 The Stabilized Form . . . . . . . . . . l36
3.3.3.2 The Ultras table Form ... . .... . 140
3.3.3.3 Dealumination of High-Silica Zeolites 142
3.3.4 Direct Replacement of Aluminum with Silicon 145
3.3.4.1 Reaction with Silicon Halides . .. . . . 145
3.3.4.2 Reaction with Hexafluorosilicates . . . 151
3.3.5 Removal of Other Framework Elements 154
3.4 Insertion into the Zeolite Framework 155
3.4.1 Reinsertion of Hydrolyzed Aluminum . 155
3.4.2 Reaction with Aluminum Compounds 157
3.4.2.1 Aqueous Aluminate 157
3.4.2.2 Aluminum Oxide . . . .. . . 158
3.4.2.3 Aluminum Halides ..... . 161
3.4.2.4 Complex Aluminum Fluoride 163
x
Contents
3.4.2.5 Generation of Vacancies Prior to Alumination .. . . . .. 163
3.4.3 Insertion of Other Elements . ... . . ...... ... .. . . . 164
3.4.3.1 Group IlIA Elements .. .. . ... ... . . ... . .. .. .. . 165
3.4.3.2 Elements of Other Groups ..... .. .. . . . ......... 167
3.5 Other Modifications . . . . . . . . . . . . . . . . . . . . . . . .. 169
3.5.1 Reactions of OH-Groups ...... . ....... . . .. .... 169
3.5.1.1 Reaction with Silanes . . . .. ... . . . . ... . . . . . . ... 170
3.5.1.2 Reaction with Phosphines .... .. .. . .. .. . .. .. . . . 172
3.5.2 Reaction with Oxoacids . . . . . . . . . . . . . . . . . . . . . . . 174
3.5.2.1 Reaction with Derivatives of Phosphorous Acid . .. . ... . . 174
3.5.2.2 Reaction with Phosphoric Acid . . . . . . . . . . . . . . . . . . . 175
References ... . .. . ... .. ... . . . . . . . .. .. . . .. 179
4 Characterization of Zeolites - Infrared and Nuclear
Magnetic Resonance Spectroscopy and X-Ray Diffraction .. 198
Hellmut G. Karge, Michael Hunger, and Hermann K. Beyer
List of Abbreviations . .. . ... . ... ....... . . . .. 198
Introduction . . . . . . . . . . . . . . . . . . . . . . . . .. 199
4.1 IR Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
4.1.1 Introduction .. . . . . . . . . . . . . . . . . . . . . . . . . 201
4.1.2 Theoretical Background .... .. .. . . . . . . . . . . . 201
4.1.3 Experimental Techniques . . . . . . . . . . . 204
4.1.3.1 Transmission IR Spectroscopy .. . . . . . . 204
4.1.3.2 Diffuse Reflectance IR (Fourier Transform)
Spectroscopy (DRIFT) ....... . .. .. . . . . . .. 206
4.1.3.3 Photo acoustic IR Spectroscopy (PAS) .. . . .. ... ... 207
4.1.3.4 Cells for Studying Zeolites and Zeolite Adsorbate Systems
by IR Spectroscopy ..... . . . .. . . .. ... . . . 208
4.1.4 Study of Framework Vibrations of Zeolites . . . . . . . . . . . . 211
4.1.5 IR Investigation of Acidic and Basic Sites in Zeolites . . . . . . . 215
4.1.5.1 Br0nsted Acid Sites (Acidic Hydroxyls) .. .. ........ . . 216
4.1.5.2 Lewis Acid Sites - True Lewis Sites . . . . . . . . . . . . . . . . . 230
4.1.5.3 Lewis Acid Sites - Cations . .. .. . ..... . ... . . . . .. 231
4.1.6 Basic Sites (Basic Hydroxyls, Basic Oxygens) .. .. . .. . ... 233
4.1.7 Zeolite-Adsorbate Systems .... . .... . . . . . .. 235
4.1.8 Motion, Diffusion and Reaction of Guest Molecules in Zeolites 238
4.2 NMR Spectroscopy .. . . .... . .... . . .... .. . . .. 239
4.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
4.2.2 Theoretical Background .... . . .... . . . . . . . . . ... 240
4.2.2.1 Zeeman Interaction and Relaxation Effects . . . . . . . . . . . . 240
4.2.2.2 Solid-State Interactions . . . . . . . . . . . . . . . . . . . 242
4.2.3 Experimental Techniques . . . . . . . . . . . . . . . . . . 245
4.2.3.1 Methods of High-Resolution Solid-State NMR . . . . . . 245
