Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC

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CHAPTER 7 technique silver leaching could be limited, a feature which has rarely been described for flame synthesized catalysts. <strong>Reactions</strong> in pressurized CO2 are popular within catalysis and the high reaction rates for the oxidation of alcohols over palladium catalysts are one example justifying the considerable research efforts in this field. Phase behavior indeed can be important and should therefore in general be considered in CO2 related studies. This can be done experimentally in a relatively simple way when the equipment – i.e. mainly a view cell – is already present. The modeling approach is an alternative when the equipment is not available and is also more flexible but of course requires substantial familiarization with the overall modeling process. The results presented here are a good starting point but more studies should follow investigating whether the proposed model can replace simple semi‐quantitative phase behavior studies in a reliable way. The catalytic results reported here differ from previously reported conclusions stating that biphasic conditions – though still close to the pressure at which phase transition occurs – result in a faster catalytic conversion. At high pressure the oxygen mass transport to the Pd surface appears to be too high. The process is very complex, phase behavior being only one parameter and is far from being completely understood. The influence of the flow on the activity and selectivity as well as the comparability between batch and continuous experiments should be investigated more carefully in order to obtain an understanding of the flow properties. Further extensive X‐ray absorption and infrared spectroscopic studies under single and two phase conditions might give insights into the origin of the pronounced response to the phase behavior. Catalysis by metal‐organic frameworks (MOFs) is a new research direction and so far the performance of many MOFs has been interesting as a property of a new material but was often inferior to established catalyst materials. Contrary to this, the MOF used in the epoxidation study investigated here showed a very promising performance though the observed solvent co‐oxidation limits the attractiveness of the studied process under economical viewpoints. Still, the broad distribution of especially homogeneous cobalt catalysts for oxidation reactions makes the MOF studied in here an interesting candidate for further catalytic studies. 182
Acknowledgements Acknowledgements This thesis and I received a lot of support during the last three years and I therefore owe many people sincere thanks. Jan‐Dierk Grunwaldt “lured” me to Denmark making this thesis possible and initiated a big step forward in my life. He supported me constantly though without dictating my work. I always had the very productive feeling that he was more of an experienced collaborator than my boss. This allowed me to develop my independence as a researcher and to fully feel responsible for this thesis with all the flaws it certainly contains though being greatly minimized by his swift proof‐reading. Many thanks! I would like to thank Anker D. Jensen who took over as my principal supervisor after Jan‐Dierk left for Karlsruhe. He helped me a lot with his engineering point of view and I appreciated his constant interest in my work. I would furthermore like to thank both Anker and Jan‐Dierk for the very important support during the writing of my research proposal. I would like to acknowledge Georgios M. Kontogeorgis for supervising me during the phase behavior study making this interesting study actually possible. I owe thanks to Alfons Baiker for allowing me to work in his group at the ETH where I certainly learned a lot. Kim Dam‐Johansen supported me in coming to Denmark and created a fruitful working environment in his department which is very much appreciated. Teaching can be cumbersome but also rewarding. I profited especially from courses taught by Kenny Ståhl, Ingmar Persson, Peter Glarborg, Jan‐Dierk Grunwaldt, Anders Riisager and Rasmus Fehrmann. Furthermore thanks to Martin Muhler, Konrad Herbst and Anders Riisager for taking over the time‐consuming task of evaluating a Ph.D. thesis. A Ph.D. study is expensive and therefore I would like to thank Haldor Topsoe A/S, DTU, MP2T and FTP for their financial support and also the European Community (within the FP‐6 Infrastructure Action “Integrating Activity on Synchrotron and Free Electron Laser Science”) and DANSCATT for granting financial help during the XAS trips. I am grateful for the possibility to measure XAS at the Swiss Light Source in Switzerland, the Angströmquelle Karlsruhe, the Hamburger Synchrotronstrahlungslabor at DESY (both Germany) and the MAX‐lab in Sweden and of course I would like acknowledge the beamline scientists for providing professional support during the measurements. Collaborating with other researchers made my work output far more efficient and so I would like to thank (in alphabetical order) Jens Enevold Thaulov Andersen (for providing ICP‐MS equipment and support during the measurements), Thomas W. Hansen (for measuring TEM), Bertram Kimmerle (for synthesis of FMF, very fruitful discussions and introducing me to equipment at ETH), Reinhard Kissner (for measuring and evaluating EPR data), Wolfgang Kleist (for discussion and coordination of 183
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TECHNICAL UNIVERSITY OF DENMARK (DT
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Preface The present dissertation su
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the carboxylic acid, ceria inhibite
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Resume Denne afhandling giver indle
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hvorimod mængden af katalysator ku
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2.3.8 Oxidation of sulfides .......
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5.3.5 Macroscopic mass transport in
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Chapter 1 Introduction With its gre
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1. Introduction Scheme 1‐1: High
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1. Introduction Figure 1‐2: Phase
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1. Introduction [28] S. Bawaked, N.
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2.1 Introduction 2.1 Introduction E
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2.2.1 Synthesis of gold catalysts 2
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2.2 Catalyst synthesis for oxidatio
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2.2 Catalyst synthesis for oxidatio
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2.3 Selective liquid‐phase oxidat
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Table 2-1: Overview over alcohol ox
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Ph O O Ph (4) (5) 2.3 Selective liq
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Table 2-4: Side-chain oxidation of
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2.3.4 Oxidation of cyclohexane 2.3
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Table 2-5: Oxidatin of cyclohexane.
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Table 2-6: Ring hydroxylation of ar
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Table 2-7: Aerobic oxidation of ami
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Table 2-8: Oxidation of hydroquinon
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Table 2-9: Oxidation of silanes wit
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Table 2-10: Oxidation reactions cat
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2.4 Strengths and opportunities of
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2.6 References 2.6 References [1] M
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2.6 References [56] H. Tumma, N. Na
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2.6 References [113] C. Keresszegi,
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2.6 References [169] Q. Zhu, Y. Lia
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2.6 References [223] M. Fetizon, M.
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Chapter 3 Selective Liquid-Phase Ox
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3.2 Experimental 3.2.1 Catalyst pre
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3.3 Results Scattering amplitudes a
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Absorption (a.u.) 1.2 1.0 0.8 0.6 0
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Conversion (%) 100 90 80 70 60 50 4
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3.3 Results Figure 3‐5: In situ X
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3.3 Results Table 3‐2: Conversion
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3.3 Results In order to gain insigh
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3.3 Results the cost of selectivity
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3.4 Discussion synergetic interacti
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3.5 Conclusions to corroborate the
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3.6 References [29] T. Mitsudome, Y
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Chapter 4 Selective Side-Chain Oxid
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4.2 Experimental single‐step flam
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4.2 Experimental alcohol (Aldrich,
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4.3 Results Scheme 4‐1: Oxidation
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4.3 Results Figure 4‐2: Formation
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4.3 Results oxidation by either 2,6
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Absorption (a.u.) Absorption (a.u.)
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4.3 Results atomic mixing of Ag and
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4.3 Results Figure 4‐7: Influence
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4.4 Discussion and mechanistic cons
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4.5 Conclusions heterogeneous radic
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4.6 References [29] S.I. Zabinsky,
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Chapter 5 Experimental Determinatio
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5.2 Experimental The most important
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5.2 Experimental Eurotherm 2216e te
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Page 189 and 190: 6.5 Conclusions Formation of the ep
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Page 199: Curriculum Vitae Matthias Josef Bei
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