3.2 New insights into high-temperature unit-cell and pore size ...

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N° d'ordre : N° attribué par la bibliothèque : THESE
en vue d'obtenir le grade de
Docteur de l'Université de Lyon - Ecole Normale Supérieure de Lyon
Spécialité : Chimie
Laboratoire de Chimie
École Doctorale de Chimie de Lyon présentée et soutenue publiquement le 30 Juillet 2008 par Monsieur Kun ZHANG
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Titre :
MESOSTRUCTURED POROUS MATERIALS:
PORE AND SURFACE ENGINEERING TOWARDS BIO-INSPIRED SYNTHESIS OF
HETEROGENEOUS COPPER CATALYSTS
Directeur de thèse : Monsieur Laurent BONNEVIOT Co-directeur de thèse : Monsieur Mingyuan HE Après avis de : Monsieur Peng WU, Rapporteur,
Monsieur Jean-Luc BLIN, Rapporteur,
Devant la Commission d'Examen formée des membres suivants :
Monsieur Peng WU, Rapporteur,
Monsieur Jean-Luc BLIN, Rapporteur,
Monsieur Joël PATARIN, Membre Monsieur Jean-Marie
HERRMANN,
Monsieur Mingyuan HE, Membre,
Membre Monsieur Laurent BONNEVIOT, Membre
Adventure journey in MCM-41 channel
'In one's life, there are only several key steps' Chinese great writer, Ai
Qing said "Going abroad to study is always my dream". In 2005, I was so
lucky and happy to be a PhD student co-directed by Prof. Laurent Bonneviot
and Prof. Ming-Yuan He, two world famous experts in catalysis and green
chemistry. Due to their choices, my dream was realized. Despite the
different nationalities, but the truth-seeking, pragmatic and innovative
scientific concept of two instructors is the same, which will deeply affect
my scientific career. I take this opportunity to express my intense
reverence towards them for bringing me into the science hall, and into the
research frontier on catalysis and green chemistry, which is closely
related to economy and society. My deepest personal regards are due for
them forever.
In the past three years, almost every day, I was able to learn something
new under the guidance of my two instructors. They let me know how to do
research, how to do systematic and in-depth scientific research
independently. If some problems were encountered during the experiment, at
any time, I could enter their rooms for help and discussed with each other
for a resolution. To solve a problem, we searched the internet, studied the
literature and check the chemical handbook till late in the day when a
phone call from home was interrupting us. On this occasion, I want to say
sorry to their families, because I took a lot of their time away from their
families. I also like to work with them, even to repair ovens, washed EPR
tubes, and changed gas bottles and so on learning from them everyday
experiment skills. During this course, a lot of research keywords: "chain
reactions on paper", "boss's eye", "patience", "details" and "why not" etc.
were heard and remembered. In addition to do research, both instructors
also regard directing students and sharing their knowledge with students as
fun. Moreover, I had the priviledge to attend an international conference
with them. To give beautiful presentations and explain our ideas, numerous
efforts were devoted to prepare posters and oral presentations to bring
attention from other researchers on your work, then discuss with us and
create opportunities for possible collaboration. For me, the most
impressive memory was that they told me a lot of wonderful stories, for
instance, on how papers may received sometimes mixed feeling and resistence
from referees before acceptance and then found a large success in the
research community. Understanding these interesting stories, I know how to
do the innovative research.
Through the channel, after experiencing the darkness, we could enjoy the
beautiful scenery inside. Obviously, like catalysts that accelerates the
transformation of reactant to final product my both instructors has
propulse my vision of the world and my personnel skills in science to a
level I could not dare to imagine at the beginning of my thesis.
Now where is my next dream? To be a professor like them will be the best
return for their rewards. [pic] Kun
Zhang
??
May 2008 Abstract
Advanced control of the surface structure and chemistry in confined space
has been developed here in mesostructured porous silicas of MCM-41 type to
design novel metal supported catalysts combining confinement,
hydrophobicity and site specificity using the inspiring model of
metalloproteins. First, it is demonstrated that the surface of such a type
of materials usually seen as smooth has indeed an alveolar structure
generated by the imprint of the ammonium surfactant head groups used here
as directing agent. Increasing hydrothermal temperatures is shown first to
enlarge the pore size by mere surface smoothing followed by a decrease
explained by wall thickening. In addition, conditions were found to
generate hybrid materials with hierarchical micro- and mesoporority.
Finally, both rough and smooth surfaces were found amenable for
multifonctionnalization using molecular stencil patterning technique and
compared for isolation of bidentate aminoethyleaminopropyl tethers by
trimethylsilyl grafted hydrophobic groups. Then copper (II) can easily be
retained by complexation to these bidentate tethers inside the nanochannels
of the material.
Résumé
Le contrôle fin de la structure et de la chimie de surface en milieu
confiné a été développé dans des silices poreuses mésostucturées de type
MCM-41 pour synthétiser des catalyseurs hétérogènes combinant confinement
moléculaire, hydrophobicité et spécificité de sites à l'instar des
métalloprotéines. La surface considérée comme lisse a en fait une rugosité
de type alvéolaire due à l'empreinte de la tête ammonium du tensioactif de
synthèse. Pour des températures croissantes du traitement hydrothermal, la
taille des mésopores augmente par érosion de cette rugosité puis diminue
par épaississement des parois. On a aussi trouvé des conditions de synthèse
de zéolihes mésoporeuses avec une micro- et mésoporosité hiérarchisée. Ces
surfaces sont polyfonctionnalisées grâce à la technique de pochoir
moléculaire pour isoler des fonctions bidentatés aminoéthylaminopropyles
par des groupements hydrophobes triméthylsimyles. Les ions cuivriques sont
alors retenus dans le matériau par complexation à ces fonctions diamino.
CONTENTS
Chapter 1 General introduction 1
1.1 Introduction 1
1.2 Enzymology study toward recoverable catalysts 1
1.3 Surfactant template mesoporous materials: from inorganic to hybrid
2
1.4 Best of two worlds 3
1.5 Outline of thesis 4
1.6 References 6
Chapter 2 General introduction and literature survey 8
2.1 Background 8
2. 2 Synthesis and formation mechanism of Mesoporous Silica 9
2. 2.1. A Brief history of Mesoporous Silica 9
2. 2.2. Formation mechanism 12
2.2.3. Proposed wall structure for MCM-41 15
2.2.3. The pore size control of MCM-41 17
2.2.4. Structure geometry control of mesoporous silica 19
2.3 Design synthesis toward the bioinspired catalyst 20
2.3 Design synthesis toward the bioinspired catalyst 21
2.3.1 Dioxygen and metalloproteins 22
2.3.2 Synthetic approach of homogeneous catalyst 26
2.3.3 Synthetic approach of biomimic or bioinspired catalyst using
mesoporous silicas as a support 27
2.4 EPR and absorption features: characterization of copper species 33
2.4.1. Electronic paramagnetic resonance of copper(II) 34
2.4.2. UV-visible characterization 36
2.5. Scope and objective of this thesis 38
2.6. References 39
Chapter 3 Surface and pore size engineering using high-temperature
postsynthesis treatment 44
3.1 Understanding the microporosity of classical MCM-41 silica 44
3.1.1 Introduction 44
3.1.2 Experimental section 47
3.1.3 Characterization 48
3.1.4 Results and discussion 49
3.1.5 Conclusions 67
3.2 New insights into high-temperature unit-cell and pore size expansion
in MCM-41 mesoporous silica 68
3.2.1 Introduction 68
3.2.2 Experimental section 70
3.2.3 Result and discussion 72
3.2.4 Conclusion 94
3.3 General conclusion and perspective 95
3.4 References 97
Chapter 4 Design synthesis of hybrid mesoporous-microporous materials 99
4.1 Introduction 99
4.2. Experimental section 101
4.2.1 Synthesis of metal free materials 101
4.2. 2 Synthesis of the hybrid materials containing Ti atom 102
4.3 Result and discussion 103
4.3.1 Synthesis of MCM-41 involved by TMA -FS-AT-x series 103
4.3.2 Synthesis of MCM-41 involved by TEA 106
4.3.3 Synthesis of hybrid materials with hierarchical porosity
involved by TPA (tetrapropyl ammonium ions) 109
4.3.4 Synthesis of crystalline hybrid materials containing Ti atom
involved by TPA 115
4.4 Conclusion and perspective 123
4.4.1 Conclusion 123