scholarly journals How to Make a Cocktail of Palladium Catalysts with Cola and Alcohol: Heteroatom Doping vs. Nanoscale Morphology of Carbon Supports

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2599
Author(s):  
Evgeniy O. Pentsak ◽  
Alexey S. Galushko ◽  
Vera A. Cherepanova ◽  
Valentine P. Ananikov
Keyword(s):  
Palladium Catalysts ◽  
Carbon Materials ◽  
Supported Catalysts ◽  
Water Solution ◽  
Reaction Medium ◽  
Textural Properties ◽  
Carbon Support ◽  
Heck Reactions ◽  
Carbon Supports ◽  
Heteroatom Doping

Sparkling drinks such as cola can be considered an affordable and inexpensive starting material consisting of carbohydrates and sulfur- and nitrogen-containing organic substances in phosphoric acid, which makes them an excellent precursor for the production of heteroatom-doped carbon materials. In this study, heteroatom-doped carbon materials were successfully prepared in a quick and simple manner using direct carbonization of regular cola and diet cola. The low content of carbon in diet cola allowed reaching a higher level of phosphorus in the prepared carbon material, as well as obtaining additional doping with nitrogen and sulfur due to the presence of sweeteners and caffeine. Effects of carbon support doping with phosphorus, nitrogen and sulfur, as well as of changes in textural properties by ball milling, on the catalytic activity of palladium catalysts were investigated in the Suzuki–Miyaura and Mizoroki–Heck reactions. Contributions of the heteroatom doping and specific surface area of the carbon supports to the increased activity of supported catalysts were discussed. Additionally, the possibility of these reactions to proceed in 40% potable ethanol was studied. Moreover, transformation of various palladium particles (complexes and nanoparticles) in the reaction medium was detected by mass spectrometry and transmission electron microscopy, which evidenced the formation of a cocktail of catalysts in a commercial 40% ethanol/water solution.

The Influence of the Substrate on Hydrogen–Water Deuterium Exchange over Carbon Supported Platinum

1972 ◽  
Vol 50 (22) ◽  
pp. 3686-3693 ◽  
Author(s):  
Norman Henry Sagert ◽  
Rita Mary Louise Pouteau
Keyword(s):  
Supported Catalysts ◽  
Water Pressure ◽  
Carbon Support ◽  
Platinum Black ◽  
Carbon Supports ◽  
Hydrogen Atoms ◽  
Hydrogen Water ◽  
Rate Determining Step ◽  
Adsorption Of Water ◽  
Carbon Catalysts

Rate data for hydrogen–water deuterium isotope exchange are reported for a number of platinum on carbon catalysts whose carbon supports were graphitized to varying degrees before the metal was deposited on the support. The exchange over platinum black was studied for comparison. Over carbon supported catalysts, the rate was almost independent of hydrogen pressure and increased approximately linearly with water pressure. The rate controlling step seems to be the transfer of deuterium between chemisorbed hydrogen atoms and physisorbed HDO.Activation energies for the rate determining step decreased from 14 kcal/mol over unsupported platinum to as low as 2 kcal/mol over highly graphitized supports. Rates increased with heat treatment temperatures up to 2100 °C. These effects are ascribed to electron transfer from the carbon support to the metal, resulting in a weaker Pt—H bond, and faster exchange. However they may be partially the result of non-linear adsorption of water.

scholarly journals Development of palladium catalysts modified by ruthenium and molybdenum as anode in direct ethanol fuel cell

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yonis Fornazier Filho ◽  
Ana Caroliny Carvalho da Cruz ◽  
Rolando Pedicini ◽  
José Ricardo Cezar Salgado ◽  
Priscilla Paiva Luz ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Palladium Catalysts ◽  
Carbon Support ◽  
X Ray Diffraction ◽  
Direct Ethanol Fuel Cell ◽  
Pd Catalysts ◽  
Bifunctional Mechanism ◽  
Catalytic Activities ◽  
Intrinsic Mechanism ◽  
Ternary Catalysts

AbstractPhysical and electrochemical properties of Pd catalysts combined with Ru and Mo on carbon support were investigated. To this end, Pd, Pd1.3Ru1.0, Pd3.2Ru1.3Mo1.0 and Pd1.5Ru0.8Mo1.0 were synthesized on Carbon Vulcan XC72 support by the method of thermal decomposition of polymeric precursors and then physically and electrochemically characterized. The highest reaction yields are obtained for Pd3.2Ru1.3Mo1.0/C and Pd1.5Ru0.8Mo1.0/C and, as demonstrated by thermal analysis, they also show the smallest metal/carbon ratio compared the other catalysts. XRD (X-ray Diffraction) and Raman analyses show the presence of PdO and RuO2 for the Pd/C and the Pd1.3Ru1.0/C catalysts, respectively, a fact not observed for the Pd3.2Ru1.3 Mo1.0 /C and the Pd1.5Ru0.8Mo1.0/C catalysts. The catalytic activities were tested for the ethanol oxidation in alkaline medium. Cyclic voltammetry (CV) shows Pd1.3Ru1.0/C exhibiting the highest peak of current density, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. From, chronoamperometry (CA), it is possible to observe the lowest rate of poisoning for the Pd1.3Ru1.0/C, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. These results suggested that catalytic activity of the binary and the ternary catalysts are improved in comparison with Pd/C. The presence of RuO2 activated the bifunctional mechanism and improved the catalytic activity in the Pd1.3Ru1.0/C catalyst. The addition of Mo in the catalysts enhanced the catalytic activity by the intrinsic mechanism, suggesting a synergistic effect between metals. In summary, we suggest that it is possible to synthesize ternary PdRuMo catalysts supported on Carbon Vulcan XC72, resulting in materials with lower poisoning rates and lower costs than Pd/C. Graphic abstract

scholarly journals Towards High Efficacy of Pd-Au/C Catalyst for Tetrachloromethane Hydrodechlorination

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 338-359
Author(s):  
Magdalena Bonarowska ◽  
Zbigniew Kaszkur ◽  
Krzysztof Matus ◽  
Alicja Drelinkiewicz ◽  
Tomasz Szumełda ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Gas Phase ◽  
Thermal Activation ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Thermal Reduction ◽  
Microwave Oven ◽  
Optimal Conditions ◽  
Catalyst Activation ◽  
Critical Part

We present an efficient strategy for synthesising the PdAu catalysts with a homogeneous PdAu alloy phase for environmentally important hydrodechlorination of tetrachloromethane in the gas phase. The synthesis of carbon-supported catalysts involved two major steps: (i) incorporation of palladium and gold nanoparticles into carbon support and (ii) activation of the catalysts. The critical part of this work was to find the optimal conditions for both steps. Thus, the incorporation of the nanoparticles was carried out in two ways, by impregnation and direct redox reaction method using acetone solutions of metal precursor salts. The activation was performed either by a conventional thermal reduction in hydrogen or flash irradiation in a microwave oven. The homogeneity and structure of the PdAu alloy were found to depend on the catalyst activation method critically. In all cases, we observed better homogeneity for catalysts that were subject to microwave irradiation. Moreover, the flash microwave irradiation of prepared catalysts provided catalysts of better stability and selectivity towards the desired products (hydrocarbons) in the hydrodechlorination of tetrachloromethane as compared to the catalyst obtained by conventional thermal activation in hydrogen.

scholarly journals Silica Monolith for the Removal of Pollutants from Gas and Aqueous Phases

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1316
Author(s):  
Vanessa Miglio ◽  
Chiara Zaccone ◽  
Chiara Vittoni ◽  
Ilaria Braschi ◽  
Enrico Buscaroli ◽  
...  
Keyword(s):  
Rhodamine B ◽  
Water Solution ◽  
Synthesis Method ◽  
Textural Properties ◽  
Adsorption Properties ◽  
Water Soluble ◽  
Silica Monoliths ◽  
Physico Chemical ◽  
Gaseous Toluene ◽  
Mcm 41

This study focused on the application of mesoporous silica monoliths for the removal of organic pollutants. The physico-chemical textural and surface properties of the monoliths were investigated. The homogeneity of the textural properties along the entire length of the monoliths was assessed, as well as the reproducibility of the synthesis method. The adsorption properties of the monoliths for gaseous toluene, as a model of Volatile Organic Compounds (VOCs), were evaluated and compared to those of a reference meso-structured silica powder (MCM-41) of commercial origin. Silica monoliths adsorbed comparable amounts of toluene with respect to MCM-41, with better performances at low pressure. Finally, considering their potential application in water phase, the adsorption properties of monoliths toward Rhodamine B, selected as a model molecule of water soluble pollutants, were studied together with their stability in water. After 24 h of contact, the silica monoliths were able to adsorb up to the 70% of 1.5 × 10−2 mM Rhodamine B in water solution.

Novel Carbon Structure as Highly Stable Support for Electro-catalyst in Acid Media: Regulating Oxygen Functionalization Behavior of Carbon

2021 ◽  
Author(s):  
Guokang Han ◽  
Yongrong Sun ◽  
Yuxin Liu ◽  
Lingfeng Li ◽  
Xudong Li ◽  
...  
Keyword(s):  
Precious Metal ◽  
Catalytic Properties ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Carbon Structure ◽  
Acid Media

The nature of carbon support has huge effects on the catalytic properties of supported catalysts. When utilized for electrochemical purposes as support for precious metal in acid media, the oxygen...

Etude de l'influence de l'ionicité du milieu réactionnel sur les propriétés texturales de gels d'oxyde de titane

1974 ◽  
Vol 52 (13) ◽  
pp. 2502-2512 ◽  
Author(s):  
Henry Brusset ◽  
Henri-Georges Mendelbaum ◽  
Chantal Flicoteaux
Keyword(s):  
Reaction Medium ◽  
Textural Properties ◽  
Low Dielectric Constant ◽  
Hydrogen Ions ◽  
Aqueous Acid ◽  
Low Dielectric ◽  
Ionic Dissociation ◽  
Two Factors ◽  
Free Hydrogen ◽  
Acid Reaction

A systematic study has been made of the influence of two factors on the synthesis of titanium dioxide gels: (i) the acidity of the reaction medium and (ii) the presence of a solvent. This study demonstrates that, in an aqueous acid medium, the development of textural properties is related to the concentration of free hydrogen ions. The presence in an acid reaction medium of a solvent, such as butanol or benzene, of low dielectric constant, inhibits the development of the structural properties by lowering the ionic dissociation of the acid. Our results provide an explanation for the apparently divergent measurements in the literature.

scholarly journals The utilization of the mesoporous Ti-SBA-15 catalyst in the epoxidation of allyl alcohol to glycidol and diglycidyl ether in the water medium

2015 ◽  
Vol 17 (4) ◽  
pp. 23-31 ◽  
Author(s):  
Agnieszka Wróblewska ◽  
Edyta Makuch ◽  
Małgorzata Dzięcioł ◽  
Roman Jędrzejewski ◽  
Paweł Kochmański ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Allyl Alcohol ◽  
Water Solution ◽  
Reaction Medium ◽  
Diglycidyl Ether ◽  
Molar Ratio ◽  
Water Medium ◽  
Catalyst Content ◽  
Allyl Alcohol Epoxidation

Abstract This work presents the studies on the optimization the process of allyl alcohol epoxidation over the Ti-SBA-15 catalyst. The optimization was carried out in an aqueous medium, wherein water was introduced into the reaction medium with an oxidizing agent (30 wt% aqueous solution of hydrogen peroxide) and it was formed in the reaction medium during the processes. The main investigated technological parameters were: the temperature, the molar ratio of allyl alcohol/hydrogen peroxide, the catalyst content and the reaction time. The main functions the process were: the selectivity of transformation to glycidol in relation to allyl alcohol consumed, the selectivity of transformation to diglycidyl ether in relation to allyl alcohol consumed, the conversion of allyl alcohol and the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed. The analysis of the layer drawings showed that in water solution it is best to conduct allyl alcohol epoxidation in direction of glycidol (selectivity of glycidol 54 mol%) at: the temperature of 10–17°C, the molar ratio of reactants 0.5–1.9, the catalyst content 2.9–4.0 wt%, the reaction time 2.7–3.0 h and in direction of diglycidyl ether (selectivity of diglycidyl ether 16 mol%) at: the temperature of 18–33°C, the molar ratio of reactants 0.9–1.65, the catalyst content 2.0–3.4 wt%, the reaction time 1.7–2.6 h. The presented method allows to obtain two very valuable intermediates for the organic industry.

Nickel Nanoparticles Supported on Diphenylphosphinated Poly(Vinyl Alcohol-Co-ethylene) as a New Heterogeneous and Recyclable Catalyst for Mizoroki–Heck Reactions

2017 ◽  
Vol 41 (9) ◽  
pp. 541-546 ◽  
Author(s):  
Farzaneh Ebrahimzadeh
Keyword(s):  
Vinyl Alcohol ◽  
Nickel Nanoparticles ◽  
Supported Catalysts ◽  
Low Cost ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
Heck Reactions ◽  
Modified Polymer ◽  
Transmission Electron ◽  
High Metal

Nickel nanoparticles (NiNPs) supported on diphenylphosphinated poly(vinyl alcohol- co-ethylene) (DPP-PVA- co-PE) were synthesised by first reacting poly(vinyl alcohol- co-ethylene) with chlorodiphenylphosphine (ClPPh2) under basic conditions and then treating the product with Ni(OAc)2 followed by reduction with NaBH4. (DPP-PVA- co-PE)-NiNPs, a new metallised polymer, was then shown to efficiently catalyse Mizoroki–Heck reactions of aryl iodides, bromides or activated chlorides with olefins such as styrene and n-butyl acrylate in dimethylformamide. In contrast with other polymer-supported catalysts, the main advantage of this method is the low cost of the catalyst due to the simple synthetic route using easily obtained materials and good recoverability. Transmission electron microscopy and X-ray diffraction measurements were used to show the high metal dispersion and small sizes of Ni nanoparticle on the surface of the modified polymer. DPP-PVA- co-PE-NiNPs could be recycled several times.

Synthesis and Properties of Nitrogen-Doped Mesoporous Carbon Materials Obtained by Templating of SBA-15 with Melamine-Formaldehyde Resin

2012 ◽  
Vol 554-556 ◽  
pp. 778-782 ◽  
Author(s):  
Chao Liu ◽  
Yong Qi Hu ◽  
Yi Feng Yu ◽  
Yue Zhang ◽  
Yan Yan Wang ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Mesoporous Carbon ◽  
Carbon Materials ◽  
Textural Properties ◽  
Formaldehyde Resin ◽  
Melamine Formaldehyde ◽  
X Ray ◽  
Nitrogen Doped ◽  
Surface Areas ◽  
Mesoporous Carbon Materials

Nitrogen-doped mesoporous carbon materials have been synthesized by using melamine-formaldehyde resin as carbon precursor and SBA-15 as a removable template. The structure of the materials was investigated by X-ray diffraction, BET specific surface area analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. X-ray and BET studies confirmed that a pore nanostructure is inherited from the silica templates. Fourier transform infrared spectroscopy analysis showed N atoms are strongly bonded in the carbon structure in heterocycles or nitrile functions. These mesoporous nitrogen-doped carbon materials exhibits textural properties with BET surface areas ranging between 400 and 600 m2/g and uniform pore size(3.9 nm). The mechanism of carbonization process is studied by thermogravimetric analysis. The ratio of melamine/formaldehyde plays an important role during the carbonization process for the surface areas and textural properties, and element analysis reveals that the nitrogen content of the mesoporous carbon materials is as high as 10wt%.

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