Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC

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(SEM), XRD and XAS. Amines (from DMF) deactivated the catalyst. The MOF catalyst featured an induction period which was not observed with homogeneously dissolved cobalt. During the induction, the catalyst was activated by benzaldehyde forming as a side‐product which led to the interesting effect that co‐epoxidation of (E)‐stilbene proceeded faster in the presence of styrene since styrene is more easily oxidized to benzaldehyde. Further catalytic studies allowed the formulation of a tentative reaction mechanism. VI
Resume Denne afhandling giver indledningsvist et overblik over heterogene kobber og sølv katalysatorer til selektiv oxidation i væskefase og sammenligner virkningsgraden og katalytiske egenskaber af disse med den i vidt omfang benyttede guld katalysator. Resultater fra litteraturen er opsummeret for alkohol oxidation, epoxidation, amin oxidation, fenyl hydroxylation, silan og sulfid oxidation, (side‐ kæde) oxidation af alkyl aromatiske stoffer, hydroquinon oxidation samt cyklohexan oxidation. Det er blevet fundet at både kobber og sølv kan fungere som komplementære katalysatormaterialer til guld, idet de udviser andre katalytiske egenskaber og er bedre egnede til kulbrinte oxidationsreaktioner. Potentielle muligheder for fremtidig forskning er heraf blevet skitseret. Potentialet af sølv som katalysator til selektiv oxidation af alkoholer er blevet undersøgt eksperimentelt. Sølv imprægneret på en silika bærer er ved en screeningsmetode fundet katalytisk aktiv sammen med en blanding af nano‐størrelse ceriumoxid. Resultaterne indikerer at den synergistiske virkning mellem ceriumoxid og sølv skyldes den fysiske kontakt imellem de to stoffer hvorimod udludning kunne udelukkes. Sølv katalysatoren udviste højest aktivitet når den var kalcineret i kort tid ved 500 °C, sandsynligvis på grund af dannelsen af sølv‐ilt specier. Fjernelsen af disse specier kan muligvis være en deaktiveringsmekanisme, hvilket blev antydet efter analyse med Røntgen‐absorbtionsspektroskopi (X‐ray absorption spectroscopy, XAS). XAS afslørede at sølv var tilstede i metallisk form. Sølv partikelstørrelserne bestemt med XAS var betydeligt mindre (2‐3 nm) end de ved transmission elektronmikroskopi (TEM) samt Røntgen‐diffraktion (XRD) bestemte størrelser (ca. 30 nm). En mulig grund kunne være at sølv‐ilt specier skabte en lokal uorden, hvilket kunne betyde at XAS underestimerede partikelstørrelsen. En foreløbig mekanisme for dehydrogenering på guld og palladium katalysatorer er blevet foreslået baseret på et katalystisk studium. Til sammenligning med kommercielle palladium og guld katalysatorer var de her dannede sølv katalysatorer mere aktive når de var til stede med ceriumoxid nanopartikler og under de testede reaktionsbetingerlser var sølv mindst lige så godt, og endda i visse tilfælde mere effektive, end guld katalysatoren. Kalicinering ved 900 °C af sølv imprægneret på silika gav en katalysator der kunne anvendes i selektiv sidekæde oxidation. Toluen, p‐xylen, etylbenzen samt cumen blev alle oxideret så de dannede de respektive hydroperoxider, alkoholer, karbonyl og karboxylsyre grupper, højst sandsynlig ved fri radikal autoxidation. p‐xylen omdannelsen blev fremmet af ceriumoxid nanopartikler i kombination med en karboxylsyre hvilket gav turn‐over‐tal (TON) op til 2000. Uden karboxylsyren VII
Page 1 and 2: TECHNICAL UNIVERSITY OF DENMARK (DT
Page 3 and 4: Preface The present dissertation su
Page 5: the carboxylic acid, ceria inhibite
Page 9 and 10: hvorimod mængden af katalysator ku
Page 11 and 12: 2.3.8 Oxidation of sulfides .......
Page 13 and 14: 5.3.5 Macroscopic mass transport in
Page 15 and 16: Chapter 1 Introduction With its gre
Page 17 and 18: 1. Introduction Scheme 1‐1: High
Page 19 and 20: 1. Introduction Figure 1‐2: Phase
Page 21 and 22: 1. Introduction [28] S. Bawaked, N.
Page 23 and 24: 2.1 Introduction 2.1 Introduction E
Page 25 and 26: 2.2.1 Synthesis of gold catalysts 2
Page 27 and 28: 2.2 Catalyst synthesis for oxidatio
Page 29 and 30: 2.2 Catalyst synthesis for oxidatio
Page 31 and 32: 2.3 Selective liquid‐phase oxidat
Page 33 and 34: Table 2-1: Overview over alcohol ox
Page 45 and 46: Ph O O Ph (4) (5) 2.3 Selective liq
Page 51 and 52: Table 2-4: Side-chain oxidation of
Page 53 and 54: 2.3.4 Oxidation of cyclohexane 2.3
Page 55 and 56: Table 2-5: Oxidatin of cyclohexane.
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2.3 Selective liquid‐phase oxidat
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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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Figure 5-1: Schematic view of the e
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(Eq. 5‐5) AB i j ε AB i j β 5.2
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(a) (b) (c) (d) (e) (f) (g) (h) (i)
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5.3 Results two association sites o
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Pressure (bar) 150 145 140 135 5.3
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5.3 Results Figure 5‐7: Oxidation
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Weight (g) 5.3 Results Figure 5‐8
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5.4 Discussion catalytic reactions
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5.4 Discussion corresponding CO2‐
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5.5 Conclusions 5.5 Conclusions The
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5.6 References [29] I. Tsivintzelis
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6.1 Introduction 6.1 Introduction A
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6.2 Experimental [38]. In a typical
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6.3 Results out in 1 mm quartz tube
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6.3 Results Figure 6‐2: Structure
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6.3 Results Figure 6‐4: Epoxidati
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6.3 Results Figure 6‐6: Compariso
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6.3 Results Figure 6‐8: Influence
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6.3 Results investigated the epoxid
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6.3 Results Figure 6‐10: Co‐epo
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6.3 Results Figure 6‐11: EXAFS an
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6.4 Discussion would need to be for
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6.5 Conclusions Formation of the ep
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6.6 References [28] J. Perles, N. S
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Chapter 7 Concluding Remarks 7.1 Co
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7.2 Final remarks and outlook speci
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Acknowledgements Acknowledgements T
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Curriculum Vitae Matthias Josef Bei
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