Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC

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CHAPTER 4 Table 4‐1: Overview over the silver catalysts prepared by flame spray pyrolysis and impregnation. Catalyst Ag (wt.‐%) CeO 2 (wt.‐%) 104 SiO 2 (wt.‐%) SSA (m 2 /g) a CeO 2 crystal size b (nm) Ag crystal size b (nm) FSP 1%Ag/SiO2 1 0 100 293 ‐ n.d. c 1 FSP 1%Ag/10%CeO2‐SiO 2 1 10 90 273 3.3 n.d. c 2 FSP 1%Ag/30%CeO2‐SiO 2 1 30 70 194 5.8 n.d. c 3 FSP 1%Ag/50%CeO2‐SiO 2 1 50 50 152 8.3 n.d. c 4 imp 10%Ag/SiO2‐900 10 0 100 128 ‐ 43 5 a Determined by nitrogen adsorption. b Determined by XRD. c Not detectable. 4.2.2 Catalyst testing Catalyst tests were performed in a three‐necked flask equipped with a gas inlet and a reflux condenser with p‐xylene (Sigma‐Aldrich >99 %), ethylbenzene (Fluka, >99 %) or cumene (Fluka, 98 %) as substrates with and without CeO2 nanoparticles (Aldrich,
4.2 Experimental alcohol (Aldrich, 98 %, p‐methyl benzaldehyde (Aldrich, 97 %), benzaldehyde (Aldrich, >99 %), benzyl alcohol (SAFC, >99 %), 2‐phenyl‐2‐propanol (Aldrich, 97 %), acetophenone (Aldrich, 99 %) and 1‐ phenyl ethanol (Aldrich, 98 %). Ethylbenzene hydroperoxide was synthesized according to ref. [27] and the response factor determined from a mixture of 1‐phenylethanol and ethylbenzene hydroperoxide. Since starting material was lost during the reaction despite using reflux condensers, yields rather than conversions and selectivities are presented from which TONs are calculated on the basis of the total amount of silver. In general, results were reproducible within an error margin of 5‐10 %. Toluene required higher temperatures than its boiling point, thus, toluene oxidation was done in an autoclave view cell (NWA GmbH, Lörrach). The autoclave was charged with 13.0 mL toluene (122 mmol), 100 mg biphenyl, 0.45 g benzoic acid, 50 mg CeO2 and 100 mg imp 10%Ag/SiO2‐900. A sample for GC analysis was taken, the autoclave was sealed and the 50 mL residual volume charged with air (10 bar, 4.2 mmol O2). The autoclave was heated up while stirring. After 1 h at the desired temperature the autoclave was cooled and opened after carefully releasing the overpressure followed by sampling for GC analysis. 4.2.3 Catalyst characterization X‐ray absorption near edge structure (XANES) / extended X‐ray absorption fine structure (EXAFS): X‐ ray absorption spectroscopy (XAS) was measured at beamline X1 at the Hamburger Synchrotronstrahlungslabor (HASYLAB) at the Deutsche Elektronen‐Synchrotron (DESY, Hamburg). XAS spectra for silver were recorded in step‐scanning mode around the Ag‐K edge (E = 25.514 keV) with a Si(311) double crystal monochromator in transmission mode and a silver foil for energy calibration. EXAFS spectra were processed by energy‐calibration, background subtraction, deglitching, normalization and Fourier‐transformed after k 3 ‐weigthing using the WinXAS 3.1 software [28]. EXAFS data fitting was performed in R‐space taking only single scattering paths within the first Ag‐Ag or Ag‐O shells into account. EXAFS data were fitted with a damping factor obtained from silver foil of 0.85. Scattering amplitudes and phase shifts were calculated with the FEFF 7.0 code [29]. X‐ray diffraction (XRD): The XRD patterns were collected with an X’Pert PRO Diffractometer (PANalytical) with a Cu‐Kα X‐ray source operated at 45 kV and 40 mA equipped with a Ni filter and a slit. Diffractograms were recorded between 2θ (Cu‐Kα) = 20° to 90° with a step width of 0.00164°. The crystallite size was estimated from Rietveld refinement using a Windows‐adapted version of the LHMP program [30]. Inductively‐coupled plasma mass spectrometry (ICP‐MS): The concentrations of cerium and silver in solution were measured by ICP‐MS (Perkin‐Elmer Elan 6000) equipped with a cross‐flow 105
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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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Page 71 and 72: Table 2-10: Oxidation reactions cat
Page 73 and 74: 2.4 Strengths and opportunities of
Page 81 and 82: 2.6 References 2.6 References [1] M
Page 83 and 84: 2.6 References [56] H. Tumma, N. Na
Page 85 and 86: 2.6 References [113] C. Keresszegi,
Page 87 and 88: 2.6 References [169] Q. Zhu, Y. Lia
Page 89 and 90: 2.6 References [223] M. Fetizon, M.
Page 91 and 92: Chapter 3 Selective Liquid-Phase Ox
Page 93 and 94: 3.2 Experimental 3.2.1 Catalyst pre
Page 95 and 96: 3.3 Results Scattering amplitudes a
Page 97 and 98: Absorption (a.u.) 1.2 1.0 0.8 0.6 0
Page 99 and 100: Conversion (%) 100 90 80 70 60 50 4
Page 101 and 102: 3.3 Results Figure 3‐5: In situ X
Page 103 and 104: 3.3 Results Table 3‐2: Conversion
Page 105 and 106: 3.3 Results In order to gain insigh
Page 107 and 108: 3.3 Results the cost of selectivity
Page 109 and 110: 3.4 Discussion synergetic interacti
Page 111 and 112: 3.5 Conclusions to corroborate the
Page 113 and 114: 3.6 References [29] T. Mitsudome, Y
Page 115 and 116: Chapter 4 Selective Side-Chain Oxid
Page 117: 4.2 Experimental single‐step flam
Page 121 and 122: 4.3 Results Scheme 4‐1: Oxidation
Page 123 and 124: 4.3 Results Figure 4‐2: Formation
Page 125 and 126: 4.3 Results oxidation by either 2,6
Page 127 and 128: Absorption (a.u.) Absorption (a.u.)
Page 129 and 130: 4.3 Results atomic mixing of Ag and
Page 131 and 132: 4.3 Results Figure 4‐7: Influence
Page 133 and 134: 4.4 Discussion and mechanistic cons
Page 135 and 136: 4.5 Conclusions heterogeneous radic
Page 137 and 138: 4.6 References [29] S.I. Zabinsky,
Page 139 and 140: Chapter 5 Experimental Determinatio
Page 141 and 142: 5.2 Experimental The most important
Page 143 and 144: 5.2 Experimental Eurotherm 2216e te
Page 145 and 146: Figure 5-1: Schematic view of the e
Page 147 and 148: (Eq. 5‐5) AB i j ε AB i j β 5.2
Page 149 and 150: (a) (b) (c) (d) (e) (f) (g) (h) (i)
Page 151 and 152: 5.3 Results two association sites o
Page 153 and 154: Pressure (bar) 150 145 140 135 5.3
Page 155 and 156: 5.3 Results Figure 5‐7: Oxidation
Page 157 and 158: Weight (g) 5.3 Results Figure 5‐8
Page 159 and 160: 5.4 Discussion catalytic reactions
Page 161 and 162: 5.4 Discussion corresponding CO2‐
Page 163 and 164: 5.5 Conclusions 5.5 Conclusions The
Page 165 and 166: 5.6 References [29] I. Tsivintzelis
Page 167 and 168: 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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