Preface

Monnier, John R.; Jale, Sudhakar Reddy; Zoeller, Joseph R.; Guliants, Vadim V.

doi:10.1007/s11244-006-0019-4

Cited by 52 publications

(83 citation statements)

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“…Ho¨lderlich et al [48,49] found that addition of Pt to Pd/ TS-1 catalysts, stabilized a surface Pd 2+ oxidation state. The optimum level of Pt was found to be a balance between the desirable increase of Pd 2+ concentration and an undesirable change in the surface morphology of the Pd aggregates, from needle-shaped to spherical [48,50]. This is in agreement with our TEM observations (5) and (6) using the rate constants reported in table 3.…”

Section: Effect Of the Second Metal On The H 2 O 2 Synthesissupporting

confidence: 90%

The issue of selectivity in the direct synthesis of H2O2 from H2 and O2: the role of the catalyst in relation to the kinetics of reaction

et al. 2006

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The kinetic behavior in the direct synthesis of H 2 O 2 with Pd-Me (Me = Ag, Pt) catalysts prepared by depositing the noble metals by electroless plating deposition (EPD) or deposition-precipitation (DP) methods on a-Al 2 O 3 asymmetric ceramic membrane with or without a further surface coating by a carbon thin layer is reported. The effect of the second metal with respect to Pd-only catalysts considerably depends on the presence of the carbon layer on the membrane support. Several factors in the preparation of these membranes as well as the reaction conditions (temperature, concentration of Br ) , pH) determine the selectivity in H 2 O 2 formation, influencing the rate of the consecutive reduction of H 2 O 2 (which is faster with respect to H 2 O 2 decomposition on the metal surface) and/or of direct H 2 + O 2 conversion to H 2 O. Defective Pd sites are indicated to be responsible for the two unselective reactions leading to water formation (parallel and consecutive to H 2 O 2 formation), but the rate constants of the two reactions are differently influenced from the catalytic membrane characteristics. Increasing the noble metal loading on the membrane not only increases the productivity to H 2 O 2 , but also the selectivity, due to the formation of larger, less defective, Pd particles.

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Section: Effect Of the Second Metal On The H 2 O 2 Synthesissupporting

confidence: 90%

The issue of selectivity in the direct synthesis of H2O2 from H2 and O2: the role of the catalyst in relation to the kinetics of reaction

et al. 2006

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“…Propylene oxide (PO) is a very important chemical feedstock for the production of a wide variety of commodity chemicals, such as polyether polyols and propylene glycol [1]. Currently, chlorohydrin and organic hydroperoxide processes are two of the commonly used industrial processes for PO synthesis in the chemical industry.…”

Section: Introductionmentioning

confidence: 99%

NaCl-Promoted CuO–RuO2/SiO2 Catalysts for Propylene Epoxidation with O2 at Atmospheric Pressures: A Combinatorial Micro-reactor Study

et al. 2014

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A combinatorial approach is used to investigate several alkali metals promoted Cu-Ru binary oxide catalysts with improved catalytic performance in the propylene partial oxidation. 2 %Cu/5 %Ru/c-SiO 2 catalyst had the best yield with high propylene conversion and propylene oxide (PO) selectivity. Among the promoters screening in the study, NaCl promotion significantly increased the PO selectivity accompanied by some attenuation in the total propylene conversion. It was proposed that binary oxide catalysts revealed a greater number of exposed catalytically active adsorption sites as compared to monometallic oxide counterparts according to XPS and FTIR results. Besides NaCl addition alters the structure, yielding a significantly improved PO selectivity without any change in the particle size of Cu and Ru oxide according to XRD analysis.

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“…Silver is an active component in oxidation catalysts [1][2][3][4][5][6][7][8][9][10][11][12][13]; most well known is its industrial application for ethene epoxidation. However, silver can also be used as a catalyst for reduction reactions, for example selective hydrogenation of unsaturated aldehydes such as acrolein and crotonaldehyde [14][15][16] or citral [17,18].…”

Section: Introductionmentioning

confidence: 99%

Activation of dihydrogen on supported and unsupported silver catalysts

Hohmeyer

Kondratenko

Bron

et al. 2010

Journal of Catalysis

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The activation of dihydrogen on silica, silver, and silica-supported silver (9 wt% Ag) was investigated. Both, silica and silver are individually able to dissociate dihydrogen. Silanol groups on silica undergo H→D exchange at 393 K in D2 as detected by IR spectroscopy. HD is observed in temporal analysis of products (TAP) experiments when H2 and D2 are sequentially pulsed on silver at 673 K; even when the time delay between the isotopes is 4 s, HD is formed, indicating that long-lived surface hydrogen species are present. Differential scanning calorimetry (DSC) shows that the activation of dihydrogen is an activated process: heat signals evoked through H2 pulses on Ag/SiO2 grow with increasing temperature (373523 K). Nonetheless, the presence of silver on the silica surface accelerates the Si-OH→Si-OD exchange. Investigation of the exchange kinetics on Ag/SiO2 shows that diffusion processes of activated hydrogen species are rate-determining at higher temperatures ( 373 K), when activation of D2 on silver becomes facile. Indications of diffusion limitation are observed already at 313 K on Pt/SiO2. TAP and DSC measurements show that H2 is more readily activated on silver that has been treated in O2 at 673 K followed by reduction in H2 at 673 K. Morphological changes induced to the silver surfaces or (sub)surface oxygen species are presumed responsible for this effect

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Preface

Cited by 52 publications

References 0 publications

The issue of selectivity in the direct synthesis of H2O2 from H2 and O2: the role of the catalyst in relation to the kinetics of reaction

The issue of selectivity in the direct synthesis of H2O2 from H2 and O2: the role of the catalyst in relation to the kinetics of reaction

NaCl-Promoted CuO–RuO2/SiO2 Catalysts for Propylene Epoxidation with O2 at Atmospheric Pressures: A Combinatorial Micro-reactor Study

Activation of dihydrogen on supported and unsupported silver catalysts

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