Search results for "Selectivity"
showing 10 items of 1148 documents
Molecular Selectivity of CO–N 2 Mixed Hydrates: Raman Spectroscopy and GCMC Studies
2020
This paper reports a novel quantitative investigation concerning the CO selectivity properties for mixed CO–N2 hydrates. The study was developed by combining Raman scattering experiments and grand ...
Nanocatalysts for High Selectivity Enyne Cyclization: Oxidative Surface Reorganization of Gold Sub-2-nm Nanoparticle Networks
2021
International audience; Ultrasmall gold nanoparticles (NPs) stabilized in networks by polymantane ligands (diamondoids) were successfully used as precatalysts for highly selective heterogeneous gold-catalyzed dimethyl allyl(propargyl)malonate cyclization to 5-membered conjugated diene. Such reaction usually suffers from selectivity issues with homogeneous catalysts. This control over selectivity further opened the way to one-pot cascade reaction, as illustrated by the 1,6-enyne cycloisomerization–Diels–Alder reaction of dimethyl allyl propargyl malonate with maleic anhydride. The ability to assemble nanoparticles with controllable sizes and shapes within networks concerns research in sensor…
Optical grating recording in ChG thin film by electron beam
2013
Abstract Recording capabilities of As Se S chalcogenide (ChG) glasses using electron beam (EB) lithography have been investigated in this study. After exposure with EB the thin films of these inorganic glasses can be etched in alkaline amine solvent with high selectivity. High resolution, smooth shaped structures have been fabricated using ChG thin films. Height of developed pattern can be controlled through changing applied electron dose.
Optimizing the nickel boride layer thickness in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in glycerol oxidation
2021
Abstract The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation. The continuously operated radial flow cell consisted of a borehole electrode positioned 50 µm above an internal reflection element enabling operando FTIR spectroscopy. It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions, additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation. The fast product identification by ATR-IR spectroscopy was validated by the …
CO2 to Liquid Fuels: Photocatalytic Conversion in a Continuous Membrane Reactor
2018
The photocatalytic reduction of CO, into value-added chemicals using sunlight is a promising approach to promote energy-bearing products, mitigating the adverse effects of anthropogenic CO2 emissions. In this work, exfoliated C3N4 was incorporated into Nafion matrix and used in a continuous photocatalytic reactor for converting CO2 into liquid fuels. Comprehensive structural and morphological diffuse reflectance spectroscopy (DRS), FT-IR, ATR-IR, and SEM measurements were performed for C3N4-loaded Nafion membrane and then compared with those of a Nafion membrane without any catalyst. The synergic effect of C3N4 organic catalyst embedded in a Nafion dense matrix and a continuous operating mo…
Adsorption of CO and N 2 molecules at the surface of solid water. A grand canonical Monte Carlo study
2020
International audience; The adsorption of carbon monoxide and nitrogen molecules at the surface of four forms of solid water is investigated by means of grand canonical Monte Carlo simulations. The trapping ability of crystalline Ih and low-density amorphous ices, along with clathrate hy-drates of structures I and II, are compared at temperatures relevant for astrophysics. It is shown that, when considering a gas phase that contains mixtures of carbon monoxide and nitrogen, the trapping of carbon monoxide is favored with respect to that of nitrogen at the surface of all solids, irrespective of the temperature. The results of the calculations also indicate that some amounts of molecules can …
Porous organic cage compounds as highly potent affinity materials for sensing by quartz crystal microbalances.
2012
Porosity makes powerful affinity materials for quartz crystal microbalances. The shape-persistent organic cages and pores create superior affinity systems to existing ones for direct tracing of aromatic solvent vapors. A shape and size selectivity for the analytes is observed. These organic cages can be processed to thin films with highly reproducible sensing properties.
Selective hydrogenation of nitroderivatives over Au/TiO2/UVM-7 composite catalyst
2020
Abstract Hydrogenation of nitroderivatives (4-nitrostyrene or 7-nitro-1-tetralone) was performed using as support a silica mesoporous material with high specific surface area (1091 m2/g) and a bimodal pore size distribution (UVM-7). Gold and/or TiO2 were deposited inside the pores of this support with the aim to achieve high activity and selectivity for this reaction. The morphology and structure of the powders have been characterized by adsorption-desorption isotherms, XRD, TEM, STEM-HAADF, XPS and ATR-FTIR. Structural characterizations shown differences between the catalysts with and without titania. The presence of TiO2 provides a better size distribution of the spherical gold nanopartic…
Cerium-Doped Copper(II) Oxide Hollow Nanostructures as Efficient and Tunable Sensors for Volatile Organic Compounds
2018
Tuning sensing capabilities of simple to complex oxides for achieving enhanced sensitivity and selectivity toward the detection of toxic volatile organic compounds (VOCs) is extremely important and remains a challenge. In the present work, we report the synthesis of pristine and Ce-doped CuO hollow nanostructures, which have much higher VOC sensing and response characteristics than their solid analogues. Undoped CuO hollow nanostructures exhibit high response for sensing of acetone as compared to commercial CuO nanoparticles. As a result of doping with cerium, the material starts showing selectivity. CuO hollow structures doped with 5 at. % of Ce return highest response toward methanol sens…
Oxygen defects: The key parameter controlling the activity and selectivity of mesoporous copper-doped ceria for the total oxidation of naphthalene
2012
Mesoporous CeO2 modified by the addition of copper has shown high efficiency for the total oxidation of naphthalene. High activity and 100% selectivity to carbon dioxide throughout the whole range of temperatures studied were achieved for copper loadings of 3.6% and lower. The catalytic behaviour has been related to the concentration of surface oxygen defects. A clear correlation between the concentration of surface oxygen defects (determined by XPS and DRIFTS) and the catalytic performance has been identified. Catalytic activity increased as copper was incorporated into the ceria up to 3.6%. In this range of copper content the copper was incorporated into the cubic fluorite lattice of CeO2…