scholarly journals Carbon-Supported Fe Catalysts forCO2Electroreduction to High-Added Value Products: A DEMS Study: Effect of the Functionalization of the Support

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
S. Pérez-Rodríguez ◽  
G. García ◽  
L. Calvillo ◽  
V. Celorrio ◽  
E. Pastor ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Ethylene Glycol ◽  
Surface Chemistry ◽  
Physicochemical Properties ◽  
Electrochemical Properties ◽  
Textural Properties ◽  
Carbon Support ◽  
Product Distribution ◽  
Added Value ◽  
Fe Catalysts

Vulcan XC-72R-supported Fe catalysts have been synthesised for the electroreduction of CO2to high-added value products. Catalysts were obtained by the polyol method, using ethylene glycol as solvent and reducing agent. Prior to the metal deposition, Vulcan was subjected to different oxidation treatments in order to modify its surface chemistry and study its influence on the physicochemical and electrochemical properties of the catalysts, as well as on the product distribution. The oxidation treatments of the supports modify their textural properties, but do not affect significantly the physicochemical properties of catalysts. However, DEMS studies showed that the carbon support degradation, the distribution of products, and the catalytic activity toward the CO2electroreduction reaction depend significantly on the surface chemistry of the carbon support.

Esterification of carboxylic acids with alkyl halides using imidazolium based dicationic ionic liquids containing bis-trifluoromethane sulfonimide anions at room temperature

RSC Advances ◽  
2015 ◽  
Vol 5 (33) ◽  
pp. 26197-26208 ◽  
Author(s):  
Arvind H. Jadhav ◽  
Kyuyoung Lee ◽  
Sangho Koo ◽  
Jeong Gil Seo
Keyword(s):  
Catalytic Activity ◽  
Ionic Liquids ◽  
Ethylene Glycol ◽  
Physicochemical Properties ◽  
Carboxylic Acids ◽  
Room Temperature ◽  
Alkyl Halides ◽  
Dicationic Ionic Liquids ◽  
Anionic Part

Task-specific RTILs of symmetrical N-methylimidazolium rings linked to an oligo (ethylene glycol) chain (cationic part) and bis-trifluoromethane sulfonimide (anionic part) were synthesized, and the physicochemical properties with catalytic activity were determined.

scholarly journals Influence of Synthesis Conditions on the Physicochemical Properties and Catalytic Activity of Fe/Cr-Pillared Bentonites

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Fatma Tomul
Keyword(s):  
Catalytic Activity ◽  
Physicochemical Properties ◽  
Conventional Method ◽  
Synthesis Method ◽  
Textural Properties ◽  
Xrd Analysis ◽  
Paramagnetic Resonance ◽  
Synthesis Conditions ◽  
Pillaring Solution ◽  
Adsorption Desorption

The synthesis of Fe/Cr-pillared bentonites starting from a 2% clay suspension and also from dry clay using ultrasound treatment for both the aging and the intercalation steps of the pillaring solution considerably reduces the time and the amount of water required compared with the conventional synthesis method. The catalysts were characterized using scanning electron microscopy with an energy dispersive system (SEM-EDS), powder X-ray diffraction (XRD), N2and CO2-adsorption/desorption, electron paramagnetic resonance (EPR), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis and the catalytic activity of selected samples was evaluated for the phenol oxidation reaction. The results of XRD analysis showed that delaminated Fe/Cr-pillared bentonite with d001value 68 Å was observed after intercalation a direct mixture of the pillaring solution and dry clay. The adsorption-desorption isotherm analysis showed that the samples synthesized with the proposed methodology in intercalation stage have similar textural properties and these properties do not change remarkably with synthesis conditions. In addition, the characterisation studies showed that the physicochemical properties of samples synthesized by ultrasound were comparable to those of sample synthesized by conventional method in this study. The sample synthesized by conventional method show 50% phenol conversion. This value was higher than those of samples synthesized by the ultrasound.

scholarly journals Controlling surface chemistry and mechanical properties of metal ionogels through Lewis acidity and basicity

2021 ◽  
Vol 9 (8) ◽  
pp. 4679-4686
Author(s):  
Coby J. Clarke ◽  
Richard P. Matthews ◽  
Alex P. S. Brogan ◽  
Jason P. Hallett
Keyword(s):  
Mechanical Properties ◽  
Ionic Liquids ◽  
Ethylene Glycol ◽  
Surface Chemistry ◽  
Lewis Acidity ◽  
Metal Species ◽  
Poly Ethylene Glycol ◽  
Acidity And Basicity ◽  
Poly Ethylene

Gels prepared from metal containing ionic liquids with cross-linked poly(ethylene glycol) have surface compositions and mechanical properties that can be controlled by Lewis basicity and acidity of the metal species.

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

Effect of sodium persulfate treatment on the physicochemical properties and catalytic activity of biochar prepared from spent malt rootlets

2021 ◽  
Vol 9 (2) ◽  
pp. 105071
Author(s):  
Paraskevi Ntzoufra ◽  
John Vakros ◽  
Zacharias Frontistis ◽  
Sotirios Tsatsos ◽  
Georgios Kyriakou ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Physicochemical Properties ◽  
Sodium Persulfate

scholarly journals Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles’ Micromeritics

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1049 ◽  
Author(s):  
Rosalía Rodríguez-Dorado ◽  
Clara López-Iglesias ◽  
Carlos García-González ◽  
Giulia Auriemma ◽  
Rita Aquino ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Textural Properties ◽  
Supercritical Drying ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Molecular Weights ◽  
Nanostructured Particles

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

scholarly journals Functionalized Poly(ethylene glycol)-Based Bioassay Surface Chemistry That Facilitates Bio-Immobilization and Inhibits Nonspecific Protein, Bacterial, and Mammalian Cell Adhesion

2007 ◽  
Vol 19 (18) ◽  
pp. 4405-4414 ◽  
Author(s):  
Gregory M. Harbers ◽  
Kazunori Emoto ◽  
Charles Greef ◽  
Steven W. Metzger ◽  
Heather N. Woodward ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Ethylene Glycol ◽  
Surface Chemistry ◽  
Mammalian Cell ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene

scholarly journals Impact of Surface Chemistry of Silicon Nanoparticles on the Structural and Electrochemical Properties of Si/Ni3.4Sn4 Composite Anode for Li-Ion Batteries

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Tahar Azib ◽  
Claire Thaury ◽  
Fermin Cuevas ◽  
Eric Leroy ◽  
Christian Jordy ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Electrochemical Properties ◽  
Large Scale ◽  
Silicon Nanoparticles ◽  
Lithium Ion ◽  
Li Ion Batteries ◽  
Chemical Homogeneity ◽  
Electrochemical Behaviors ◽  
Pure Silicon ◽  
Li Ion

Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni3Sn4 composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi2, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni3Sn4 composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni3Sn4 during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni3Sn4-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles.

Synthesis of Macro-Porous De-NOx Catalysts for Poly-Tetra-Fluoro-Ethylene Membrane Bag Filter

2021 ◽  
Vol 21 (8) ◽  
pp. 4537-4543
Author(s):  
Byung Chan Kwon ◽  
Dohyung Kang ◽  
Seung Woo Lee ◽  
No-Kuk Park ◽  
Jang Hun Lee ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nitrogen Oxides ◽  
Porous Alumina ◽  
Combustion Process ◽  
Textural Properties ◽  
Filter Material ◽  
Facilitated Diffusion ◽  
Exhaust Gas ◽  
Bag Filter ◽  
Combustion Exhaust

This study examined the effects of the porosity of catalytic bag-filter materials for applications to the SNCR (selective noncatalytic reduction)-SCR (selective catalytic reduction) hybrid process for highly treating nitrogen Oxides (NOx) in the exhaust gas of a combustion process. A V2O5/TiO2 catalyst was dispersed in a PTFE (poly-tetra-fluoro-ethylene) used as the catalytic bag-filter material to remove particulate matter and nitrogen oxides contained in the combustion exhaust gas. Macroporous alumina was added into a V2O5/TiO2-dispersed PTFE to improve the catalytic activity of V2O5/TiO2 dispersed in the PTFE material. In this study, the textural properties and denitrification performances of the V2O5/TiO2-dispersed PTFE materials were examined according to the addition of macro-porous alumina. When the denitrification catalyst was solely dispersed in the PTFE material, the catalyst inside the PTFE backbone had low gas-solid contact efficiency owing to the low porosity of the PTFE materials, resulting in low denitrification efficiency. On the other hand, the catalytic activity of V2O5/TiO2 dispersed inside the macro-porous PTFE material was significantly enhanced by adding macro-porous alumina into the PTFE matrix. The enhanced textural properties of the macro-porous PTFE material where V2O5/TiO2 was uniformly dispersed proved the facilitated diffusion of combustion exhaust gas into the PTFE material.

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