Mechanistic studies of the methanol-to-olefin process on acidic zeolite catalysts by in situ solid-state NMR-UV, Vis spectroscopy [Elektronische Ressource] / vorgelegt von Yijiao Jiang
136 Pages
English
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Mechanistic studies of the methanol-to-olefin process on acidic zeolite catalysts by in situ solid-state NMR-UV, Vis spectroscopy [Elektronische Ressource] / vorgelegt von Yijiao Jiang

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136 Pages
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Published 01 January 2007
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Mechanistic Studies of the Methanol-to-olefin Process on Acidic
Zeolite Catalysts by In Situ Solid-state NMR-UV/Vis Spectroscopy


Von der Fakultät Chemie der Universität Stuttgart
zur Erlangung der Würde eines
Doktors der Naturwissenschaften (Dr. rer. nat.)
genehmigte Abhandlung



vorgelegt von
Yijiao Jiang
aus Zhe’jiang, V.R. China




Hauptberichter: Prof. Dr. Michael Hunger
Mitberichter: Prof. Dr. Emil Roduner



Tag der mündlichen Prüfung: 05.10.2007


Institut für Technische Chemie
der Universität Stuttgart
2007























Dedicated to my parents. Acknowledgment

I would first like to acknowledge the Graduate College “Modern Methods of Magnetic
Resonance in Materials Science” for passing on to me numerous fascinating aspects of
spectroscopic techniques as well as for the very instructional lectures, seminars and
workshops with their unforgettable, pleasant, and very promotional atmosphere.

I would like to express my deepest gratitude to my supervisor Prof. Dr. Michael Hunger for
his scientific insights and trustworthy advice during the work during the work with this thesis.
Sincerest thanks are also given to Prof. Dr. Wei Wang and Dr. Aswin Verhoeven for their
fruitful discussions and comments throughout my PhD study.

I am also grateful to Prof. Dr. Emil Roduner and Prof. Dr. Thomas Schleid for their readiness
to be my co-examiners.

I would like to take this opportunity to express my sincere thanks to our institute leader Prof.
Dr.-Ing. Jens Weitkamp for his encouragement and support of my work.

My special thanks are given to Mrs. Ute Albrecht and Mrs. Inge Blankenship who helped me
a lot in all kinds of administration problems and contributed to a pleasant atmosphere in my
institute and the Graduate College, respectively. I wish also to thank all the colleagues: Dr. R.
Gläser, Dr. Y. Traa, Dr. T. Donauer, Dr. S. Altwasser, Dr. C. Berger, Dr. P. De Cola, Dr. S.
Laha, Dr. J. Jiao, F. Demir, D. Singer, T. Schreiber, V.R.R Marthala, S. Rabl, E. Rezaei, I.
Nägele, A. Stieber, B. Gehring, H. Fingerle, L. Valiente, A. Telfah, and so on, for their help
and friendship during these years, without which could have made the completion of this
degree more difficult.

Last but not least I would like to thank my dear husband Jun and my family for their
continuous encouragement and support.
Contents I
1 Abbreviations and Symbols...................................................................................... 1
1.1 Abbreviations .............................................................................................................. 1
1.2 Symbols....................................................................................................................... 2
2 Zusammenfassung..................................................................................................... 4
3 Abstract.................................................................................................................... 10
4 Objectives and Organization of this Dissertation ................................................ 14
4.1 General Introduction and Main Objectives ............................................................... 14
4.2 Organization of this Dissertation............................................................................... 16
5 Introduction ............................................................................................................. 17
5.1 Methanol-to-olefin Process ....................................................................................... 17
5.1.1 Background...... 17
5.1.2 Acidic Zeolite Catalysts ............................................................................................ 18
5.1.3 Mechanisms of the MTO Process ............................................................................. 22
5.1.4 Industrial Processes...................................................................................................25
5.2 Solid-state NMR and UV/Vis Spectroscopy in Heterogeneous Catalysis ................ 27
5.2.1 Introduction............................................................................................................... 27
5.2.2 Solid-state NMR Spectroscopy.................................................................................28
5.2.3 Diffuse Reflectance UV/Vis Spectroscopy............................................................... 34
5.2.4 In situ MAS NMR-UV/Vis Spectroscopy................................................................. 36
6 Preparation and Characterization of Acidic Catalysts........................................ 38
6.1 Preparation of Acidic Catalysts 38
6.1.1 Preparation of H-SAPO-34 ....................................................................................... 38
6.1.2 Preparation of H-Y....................................................................................................39
6.2 Characterization of Acidic Catalysts......................................................................... 39
6.2.1 X-Ray Powder Diffraction Analysis 39
6.2.2 Elemental and Thermogravimetric Analysis............................................................. 40
6.2.3 Multinuclear Solid-state MAS NMR Spectroscopy.................................................. 40
7 Effect of Organic Impurities on the Hydrocarbon Formation via the
Decomposition of Surface Methoxy Species on Acidic Zeolite Catalysts........... 46
7.1 Introduction............................................................................................................... 46
7.2 Experimental Part......................................................................................................47
7.2.1 Sample Preparation...................................................................................................
137.2.2 C MAS NMR and UV/Vis Investigations .............................................................. 48
7.3 Results and Discussion.............................................................................................. 49
17.3.1 H MAS NMR Investigation of the Identical Formation of Surface Methoxy
13 Species by C -enriched and Non-enriched Methanol ............................................. 49
7.3.2 MAS NMR-UV/Vis Investigation of the Conversion of Surface Methoxy Species on
Methylated Zeolite Y (CH -Y).................................................................................. 52 3
7.3.3 ation of the
the Methylated SAPO-34 (CH -SAPO-34)............................................................... 55 3II Contents
7.3.4 Effect of Ethanol and Acetone on the Formation of Primary Hydrocarbons on
H-SAPO-34 ............................................................................................................... 57
7.4 Conclusions60
8 Reactivity of Surface Methoxy Species Formed on Acidic Zeolites.................... 62
8.1 Introduction ............................................................................................................... 62
8.2 Experimental Part...................................................................................................... 63
8.2.1 Sample Preparation...................................................................................................63
138.2.2 C MAS NMR Investigations .................................................................................. 64
8.3 Results....................................................................................................................... 64
8.3.1 Reaction of Surface Methoxy Species and Ammonia at Room Temperature........... 64
8.3.2 Reaction of Surface Methoxy Species and Alkyl Halides ........................................ 67
8.3.3 ecies and Hydrochloride ....................................... 71
8.3.4 Koch-type Carbonylation Reaction: The Reaction of Surface Methoxy Species and
Carbon Monoxide...................................................................................................... 72
8.3.5 Ritter-type Reaction: The Reaction of Surface Methoxy Species and Acetonitrile.. 75
8.3.6 Oxidation of Surface Methoxy Species..................................................................... 77
8.4 Discussion and Conclusions...................................................................................... 79
9 Coke Formation during the Methanol-to-olefin Conversion on Acidic Zeolites
H-SAPO-34 in the Fixed-bed Reactor Characterized by In Situ UV/Vis and
MAS NMR Spectroscopy........................................................................................ 88
9.1 Introduction ............................................................................................................... 88
9.2 Experimental Part...................................................................................................... 89
9.2.1 Experimental Equipment...........................................................................................89
9.2.2 Catalytic Reaction Conditions................................................................................... 90
9.3 Results and Discussion.............................................................................................. 91
9.3.1 Study of Coke Formation during the Methanol Conversion on H-SAPO-34 by In
Situ UV/Vis Spectroscopy and Online GC Analysis ................................................ 91
9.3.2 Quantitative Evolution of Coke Deposits Formed during the Methanol Conversion
on H-SAPO-34 in the Fixed-bed Reactor ................................................................. 93
9.3.3 Study of the Isotopic Composition of the Organic Deposits Formed by Conversion
13of Non-enriched and C-enrichced Methanol on H-SAPO-34 Catalysts ................ 95
9.4 Conclusions...............................................................................................................97
10 In Situ MAS NMR-UV/Vis Spectroscopic Study of Hydrocarbon-pool
Compounds Formed during the Methanol-to-olefin Conversion on H-SAPO-34
under Continuous-flow Conditions ....................................................................... 99
10.1 Introduction............................................................................................................... 99
10.2 Experimental Part......................................................................................................99
10.2.1 ExperimeEquipment...........................................................................................
10.2.2 Catalytic Reaction Conditions................................................................................. 100
10.3 Results and Discussion............................................................................................101
10.3.1 In situ CF MAS NMR-UV/Vis Spectroscopy of the Methanol-to-olefin Conversion
on H-SAPO-34 ........................................................................................................ 101 Contents III
1310.3.2 Quantitative C MAS NMR Investigation of Hydrocarbon-pool Compounds on
H-SAPO-34 Formed under Continuous-flow Conditions....................................... 105
10.3.3 MAS NMR-UV/Vis Investigation of the Regeneration of the Used H-SAPO-34
Catalysts by Purging with Synthetic Air................................................................. 107
10.4 Conclusions.............................................................................................................109
Literatures............................................................................................................................. 111
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