Simultaneous adsorption of benzene and dioxygen in CuHY zeolites as a precursor process to the aerobic oxidation of benzene to phenol

Santra, Shampa; Stoll, Hermann; Rauhut, Guntram

doi:10.1039/b921531j

Cited by 11 publications

(7 citation statements)

References 54 publications

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“…4, again for benzene oxidation, but here on zeolite CuHY. 12 A hybrid method is used which calculates the immediate environment of the catalytic centre at a high quantum chemical (QC) level. This accurately treated cluster is embedded in the somewhat further remote environment which is treated at the less accurate molecular mechanics (MM) level that works with empirical force fields.…”

Section: Emil Rodunermentioning

confidence: 99%

Understanding catalysis

2014

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The large majority of chemical compounds underwent at least one catalytic step during synthesis. While it is common knowledge that catalysts enhance reaction rates by lowering the activation energy it is often obscure how catalysts achieve this. This tutorial review explains some fundamental principles of catalysis and how the mechanisms are studied. The dissociation of formic acid into H2 and CO2 serves to demonstrate how a water molecule can open a new reaction path at lower energy, how immersion in liquid water can influence the charge distribution and energetics, and how catalysis at metal surfaces differs from that in the gas phase. The reversibility of catalytic reactions, the influence of an adsorption pre-equilibrium and the compensating effects of adsorption entropy and enthalpy on the Arrhenius parameters are discussed. It is shown that flexibility around the catalytic centre and residual substrate dynamics on the surface affect these parameters. Sabatier's principle of optimum substrate adsorption, shape selectivity in the pores of molecular sieves and the polarisation effect at the metal-support interface are explained. Finally, it is shown that the application of a bias voltage in electrochemistry offers an additional parameter to promote or inhibit a reaction.

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Section: Emil Rodunermentioning

confidence: 99%

Understanding catalysis

2014

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“…Transition states were searched by Dmol3 with the complete QST/LST option, for which linear synchronous transit (LST) maximization was performed for the coordinates interpolated between a reactant and a product, followed by repeated conjugated gradient minimizations and quadratic synchronous transit (QST) maximizations until a transition state was located . It is noted that quantum mechanics/molecular mechanics calculations were successful for some metal clusters in the zeolite framework . To include the effect of the zeolite framework, a β‐ zeolite framework model was prepared from the crystal structure of β‐zeolite with hydrogen atom termination.…”

Section: Methodsmentioning

confidence: 99%

Structure of the Active Platinum Cluster and Reaction Pathway of the Selective Synthesis of Phenol from Benzene and Oxygen Regulated with Ammonia on a Platinum Cluster/β‐Zeolite Catalyst Studied by DFT Calculations

Sasaki

Tada

Wang

et al. 2015

Chemistry An Asian Journal

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DFT calculations were used to investigate the structure of the active Pt cluster and the catalytic reaction pathway for the selective synthesis of phenol from benzene and molecular oxygen regulated with ammonia on a Pt cluster/β-zeolite catalyst that was reported to be active for the selective hydroxylation of benzene only in the coexistence of ammonia. It was found that Pt5-Pt6 clusters were active for the direct synthesis of phenol, and they provided the reaction sites for bond rearrangements among ammonia, oxygen, and benzene; furthermore, the coexistence of ammonia was crucial for the selective oxidation of benzene to phenol, as it suppressed benzene combustion to CO2 and promoted the selective synthesis of phenol. It was further found that water coexisting in the system also played a significant role in desorbing phenol on the Pt cluster surface, which resulted in promotion of the overall selective synthesis of phenol. The energy diagram for the reaction sequences and the structures of the transition states were obtained, which indicated the origin of the Pt/β catalysis.

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“…[26][27][28][29][30] Thus, extensive efforts have so far been made to develop a one-step oxygenation process of benzene to phenol using heterogeneous inorganic catalysts. [31][32][33][34][35][36][37][38][39][40] In contrast to inorganic catalysts, which afford only low yields of phenol, an organic dye, 3-cyano-1-methylquinolinium ion (QuCN + ) acts as an efficient photocatalyst for the selective oxygenation of benzene to phenol with dioxygen (O 2 ) and water (H 2 O) under homogeneous and ambient conditions (vide infra). 41 Photocatalytic oxygenation of benzene with O 2 and H 2 O occurs under photoirradiation of QuCN + ClO 4 À (l max ¼ 330 nm), in oxygen-saturated acetonitrile (MeCN) containing benzene and H 2 O, with a xenon lamp (500 W) attached with a color-cut glass lter (l ¼ 290-600 nm) to yield phenol and hydrogen peroxide [eqn (1)].…”

Section: Oxygenation Of Benzenementioning

confidence: 99%

Selective photocatalytic reactions with organic photocatalysts

2013

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Selective photocatalytic oxygenation of various substrates has been achieved using organic photocatalysts via photoinduced electron-transfer reactions of photocatalysts with substrates and dioxygen under visible light irradiation. Photoinduced electron transfer from benzene to the singlet-excited state of the 3-cyano-1-methylquinolinium ion has enabled the oxidation of benzene by dioxygen with water to yield phenol selectively. Alkoxybenzenes were obtained when water was replaced by alcohols under otherwise the same experimental conditions. Photocatalytic selective oxygenation reactions of aromatic compounds have also been achieved using an electron donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr + -Mes) acting as a photocatalyst and dioxygen as an oxidant under visible light irradiation. The oxygenation reaction is initiated by intramolecular photoinduced electron transfer from the mesitylene moiety to the singlet-excited state of the acridinium moiety of Acr + -Mes to afford an extremely longlived electron-transfer state. The electron-transfer state can oxidize and reduce substrates and dioxygen, respectively, leading to selective oxygenation and halogenation of substrates. C-C bond formation of substrates has also been made possible by using Acr + -Mes as a photocatalyst.

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Simultaneous adsorption of benzene and dioxygen in CuHY zeolites as a precursor process to the aerobic oxidation of benzene to phenol

Cited by 11 publications

References 54 publications

Understanding catalysis

Understanding catalysis

Structure of the Active Platinum Cluster and Reaction Pathway of the Selective Synthesis of Phenol from Benzene and Oxygen Regulated with Ammonia on a Platinum Cluster/β‐Zeolite Catalyst Studied by DFT Calculations

Selective photocatalytic reactions with organic photocatalysts

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