Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC

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CHAPTER 4 Table 4‐5: <strong>Oxidation</strong> of ethylbenzene with silver catalysts in the presence of CeO2 and carboxylic acid. Reaction conditions: 122 mmol ethylbenzene, 3 mol‐% benzoic acid, 100 mg biphenyl, 100 mg catalyst, oxygen atmosphere, reflux, 3 h reaction time. Yields (%) Catalyst OH O OOH Cumene oxidation gave mainly cumene hydroperoxide, acetophenone and 2‐phenyl‐2‐propanol (Table 4‐6 and Figure 4‐7b) with minor side products being benzaldehyde and α‐methyl styrene. The hydroperoxide exhibited transient behavior, i.e. its yield exhibited a maximum after 1‐2 hours in the presence of carboxylic acid and CeO2. Interestingly, FSP catalysts supported on CeO2‐SiO2 generally resulted in lower yields (Table 4‐6, entries 2‐4). Even in the presence of added ceria nanoparticles the obtained yield was higher for imp 10%Ag/SiO2‐900 (entry 1). One of the reasons for this difference might be the close proximity between ceria and silver being the radical initiator for CeO2‐SiO2 supported FSP catalysts and the smaller CeO2 particle size (cf. Table 4‐1, 3‐8 nm, compared to 25 nm for the commercial ceria) but also leaching must be considered (vide infra). Ceria added to imp 10%Ag/SiO2‐900 had a deactivating effect even in the presence of benzoic acid (Figure 4‐7b) as also observed for ethylbenzene oxidation. Interestingly, flame synthesized silver catalysts with SiO2‐ CeO2 support gave not only lower overall yields but also an altered product distribution. Only small amounts of alcohol and peroxide were formed (which are the main products in the reactions with the impregnated Ag catalysts) the main product being acetophenone. These alterations indicate a different reaction mechanism and are probably due to a changing ratio of the reaction rates of chain termination vs. propagation and the suppression of some radical reaction pathways. When imp 10%Ag/SiO2‐900 was used as a catalyst, the oxidation of ethylbenzene and cumene continued after removal of the solid phase. In case of cumene a silver concentration of 9 mg/L was found by ICP‐MS while for FSP 1%Ag/10%CeO2‐SiO2 the silver concentration was below the detection limit. This 116 Combined TON Entry imp 10%Ag/SiO2‐900 4.4 11.8 4.1 20.3 290 1 FSP 1%Ag/10%Ce/SiO2 4.0 6.8 4.2 15.0 2000 2 FSP 1%Ag/30%Ce/SiO2 2.0 3.8 6.0 11.8 1600 3 FSP 1%Ag/50%Ce/SiO2 1.7 3.2 1.8 6.7 890 4 SiO2 < 0.1 < 0.1 0.8 0.9 ‐ 5
4.3 Results Figure 4‐7: Influence of the carboxylic acid and CeO2 on the oxidation of ethylbenzene (a) and cumene (b). Reaction conditions: 122 mmol ethylbenzene or cumene, optionally 3 mol‐% benzoic acid and 50 mg CeO2, 100 mg biphenyl, 100 mg imp 10%Ag/SiO2‐900, oxygen atmosphere, 140 °C, 3 h reaction time. 117
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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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Page 79 and 80: 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 and 118: 4.2 Experimental single‐step flam
Page 119 and 120: 4.2 Experimental alcohol (Aldrich,
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: 4.3 Results atomic mixing of Ag and
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
Page 169 and 170: 6.2 Experimental [38]. In a typical
Page 171 and 172: 6.3 Results out in 1 mm quartz tube
Page 173 and 174: 6.3 Results Figure 6‐2: Structure
Page 175 and 176: 6.3 Results Figure 6‐4: Epoxidati
Page 177 and 178: 6.3 Results Figure 6‐6: Compariso
Page 179 and 180: 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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