Controlling Multiple Active Sites on Pd‐CeO2 for Sequential C‐C Cross‐coupling and Alcohol Oxidation in One Reaction System

ChemCatChem ◽  
2021 ◽  
Author(s):  
Wonjae Ko ◽  
Ju Hee Kim ◽  
Guk Hee Yim ◽  
Seong Chan Lee ◽  
Sumin Kim ◽  
...  
Keyword(s):  
Active Sites ◽  
Reaction System ◽  
Cross Coupling ◽  
Alcohol Oxidation

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenolysis of thiophene

1980 ◽  
Vol 45 (10) ◽  
pp. 2728-2741 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Kinetic Equations ◽  
Reaction System ◽  
Reaction Products ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Reaction Schemes

Kinetics have been studied of the reaction system taking place during the reaction of thiophene on the cobalt-molybdenum catalyst in a gradientless circulation flow reactor at 360 °C and atmospheric pressure. Butane has been found present in a small amount in the reaction products even at very low conversion. In view of this, consecutive and parallel-consecutive (triangular) reaction schemes have been proposed. In the former scheme the appearance of butane is accounted for by rate of desorption of butene being comparable with the rate of its hydrogenation. According to the latter scheme part of the butane originates from thiophene via a different route than through hydrogenation of butene. Analysis of the kinetic data has revealed that the reaction of thiophene should be considered to take place on other active sites than that of butene. Kinetic equations derived on this assumption for the consecutive and the triangular reaction schemes correlate experimental data with acceptable accuracy.

scholarly journals Heterogeneous Catalytic Synthesis of 2-Methylbenzimidazole from 2-Nitroaniline and Ethanol Over Mg Modified Cu-Pd/γ-Al2O3

Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Feng Feng ◽  
Yaqin Deng ◽  
Zheng Cheng ◽  
Xiaoliang Xu ◽  
Qunfeng Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrogen Transfer ◽  
High Efficiency ◽  
Simple Procedure ◽  
Direct Synthesis ◽  
Reaction System ◽  
Simple Method ◽  
Heterogeneous Catalytic ◽  
Coupled Reaction ◽  
Al2o3 Catalyst

The direct synthesis of benzimidazoles from 2-nitroaniline and ethanol over Cu-Pd/γ-Al2O3 catalysts has the advantages of requiring easily available starting materials, having high efficiency, and a simple procedure. The modification by Mg of the Cu-Pd/γ-Al2O3 catalyst could improve the catalytic activity significantly. The addition of Mg to the Cu-Pd/γ-Al2O3 catalyst could maintain and promote the formation of CuPd alloy active sites. Meanwhile, the basicity of the support was enhanced appropriately by Mg, which generated more basic sites (Al-Oδ−) to accelerate the dehydrogenation of alcohol and increased the rate of the whole coupled reaction. The 2-nitroaniline was completely converted over Cu-Pd/(Mg)γ-Al2O3 after reacting for six hours, and the yield of 2-methylbenzimidazole was 98.8%. The results of this work provide a simple method to develop a more efficient catalyst for the “alcohol-dehydrogenation, hydrogen transfer and hydrogenation” coupled reaction system.

scholarly journals Biomimetic Cu/Nitroxyl Catalyst Systems for Selective Alcohol Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 395 ◽  
Author(s):  
Lindie Marais ◽  
Andrew John Swarts
Keyword(s):  
Active Sites ◽  
Alcohol Oxidation ◽  
Galactose Oxidase ◽  
Co Catalyst ◽  
Co Catalysts ◽  
Mechanistic Pathway ◽  
Oxidation Of Alcohols ◽  
Catalyst Systems ◽  
Carbonyl Products

The oxidation of alcohols to the corresponding carbonyl products is an important organic transformation and the products are used in a variety of applications. The development of catalytic methods for selective alcohol oxidation have garnered significant attention in an attempt to find a more sustainable method without any limitations. Copper, in combination with 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) and supported by organic ligands, have emerged as the most effective catalysts for selective alcohol oxidation and these catalyst systems are frequently compared to galactose oxidase (GOase). The efficiency of GOase has led to extensive research to mimic the active sites of these enzymes, leading to a variety of Cu/TEMPO· catalyst systems being reported over the years. The mechanistic pathway by which Cu/TEMPO· catalyst systems operate has been investigated by several research groups, which led to partially contradicting mechanistic description. Due to the disadvantages and limitations of employing TEMPO· as co-catalyst, alternative nitroxyl radicals or in situ formed radicals, as co-catalysts, have been successfully evaluated in alcohol oxidation. Herein we discuss the development and mechanistic elucidation of Cu/TEMPO· catalyst systems as biomimetic alcohol oxidation catalysts.

Thieme Chemistry Journals Awardees – Where Are They Now? Synthesis of a Dinuclear Copper NHC Complex Bearing a Rigid π-Conjugated Cyclic Framework

Synlett ◽  
2017 ◽  
Vol 28 (14) ◽  
pp. 1775-1779
Author(s):  
Daiki Inamori ◽  
Takuya Miwa ◽  
Tetsuaki Fujihara ◽  
Yasushi Tsuji ◽  
Jun Terao
Keyword(s):  
Active Sites ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Dinuclear Complexes ◽  
Homogeneous Catalysts ◽  
Dinuclear Copper ◽  
Cross Coupling Reaction ◽  
Catalytically Active

Macrocyclic dinuclear complexes have been gaining popularity in the design of homogeneous catalysts. Herein, we report the design of such a complex featuring catalytically active sites fixed inside the ring and its synthesis using a cross-coupling reaction.

scholarly journals Effects of NO<sub>2</sub> and C<sub>3</sub>H<sub>6</sub> on the heterogeneous oxidation of SO<sub>2</sub> on TiO<sub>2</sub> in the presence or absence of UV–Vis irradiation

2019 ◽  
Vol 19 (23) ◽  
pp. 14777-14790 ◽  
Author(s):  
Biwu Chu ◽  
Yali Wang ◽  
Weiwei Yang ◽  
Jinzhu Ma ◽  
Qingxin Ma ◽  
...  
Keyword(s):  
Active Sites ◽  
Heterogeneous Reaction ◽  
Reaction System ◽  
Heterogeneous Reactions ◽  
Heterogeneous Oxidation ◽  
Inorganic Species ◽  
Sulfate Formation ◽  
Dark Conditions ◽  
Diffuse Reflectance Infrared ◽  
Reaction Processes

Abstract. The heterogeneous reactions of SO2 in the presence of NO2 and C3H6 on TiO2 were investigated with the aid of in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) under dark conditions or with UV–Vis irradiation. Sulfate formation with or without the coexistence of NO2 and/or C3H6 was analyzed with ion chromatography (IC). Under dark conditions, SO2 reacting alone resulted in sulfite formation on TiO2, while the presence of parts per billion (ppb) levels of NO2 promoted the oxidation of SO2 to sulfate. The presence of C3H6 had little effect on sulfate formation in the heterogeneous reaction of SO2 but suppressed sulfate formation in the heterogeneous reaction of SO2 and NO2. UV–Vis irradiation could significantly enhance the heterogeneous oxidation of SO2 on TiO2, leading to copious generation of sulfate, while the coexistence of NO2 and/or C3H6 significantly suppressed sulfate formation in experiments with UV–Vis lights. Step-by-step exposure experiments indicated that C3H6 mainly competes for reactive oxygen species (ROS), while NO2 competes with SO2 for both surface active sites and ROS. Meanwhile, the coexistence of NO2 with C3H6 further resulted in less sulfate formation compared to introducing either one of them separately to the SO2–TiO2 reaction system. The results of this study highlighted the complex heterogeneous reaction processes that take place due to the ubiquitous interactions between organic and inorganic species and the need to consider the influence of coexisting volatile organic compounds (VOCs) and other inorganic gases in the heterogeneous oxidation kinetics of SO2.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenation of ethylene and butene

1980 ◽  
Vol 45 (10) ◽  
pp. 2742-2750 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Reaction System ◽  
Circulation Flow ◽  
Kinetic Description ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Hydrogenation Of Ethylene

Hydrogenation has been studied of ethylene and butene in a circulation flow reactor on a cobalt-molybdenum catalyst at 360 °C and atmospheric pressure. The effect has been investigated of simultaneous hydrodesulphurization of thiophene on the hydrogenation. The results have confirmed that different active sites for hydrogenation and hydrodesulphurization must be considered in the kinetic description of simultaneous hydrogenation of ethylene and hydrodesulphurization of thiophene. For isolated hydrogenation of ethylene and butene the absence of hydrogen sulphide in the reaction mixture considerably enhances the hydrogenation activity of the catalyst due to the change of its state.

Bimetallic PdCu Nanoparticle Catalyst Supported on Hydrotalcite for Selective Aerobic Oxidation of Benzyl Alcohol

2015 ◽  
Vol 1760 ◽  
Author(s):  
Shun Nishimura ◽  
Nao Yoshida ◽  
Kohki Ebitani
Keyword(s):  
Benzyl Alcohol ◽  
Precious Metal ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Alcohol Oxidation ◽  
Dark Field ◽  
Solid Base ◽  
X Ray ◽  
Benzyl Alcohol Oxidation ◽  
Bimetallic Nanoparticle

ABSTRACTTo decrease the amount of precious metal usage for Pd-catalyzed aerobic alcohol oxidation, various amount of Cu-contained Pd bimetallic nanoparticle-supported solid base hydrotalcite catalyst (PdxCuy-PVP/HTs) were prepared and applied for aerobic benzyl alcohol oxidation. It was found that the addition of Cu atoms into Pd in the range of 0-40% provided a similar or a little superior activity to that of Pd100-PVP catalyst, whereas a large quantity of co-existence Cu (>40%) gradually decreased their activity of the catalyst. The aerobic benzyl alcohol oxidation over Pd80Cu20-PVP/HT served 77% yield and 95% selectivity towards benzaldehyde at 313 K for 5 h in toluene under O2 flow. X-ray adsorption spectroscopy (XAS) studies and scanning transmission electron microscopy-high angle annuar dark field (STEM-HAADF) with energy dispersive X-ray spectroscopy (EDS) analyses suggested that Cu atoms doping into Pd(0) NP influenced not only localized nanostructure but also oxidation state around Pd atoms. We suggested that substitution of precious metal with small amount of transition metals such as Cu lead to geometric/electronic changes in active sites would be one of nice strategies for reducing the cost for the catalyst in the oxidation process.

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