نتایج جستجو برای: shape selective catalysts
تعداد نتایج: 415754 فیلتر نتایج به سال:
We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stere...
Highly active magnetically recyclable hollow nanocomposite catalysts with a permeable carbon surface have been prepared by a simple, economical and scalable process. The designed nanocomposite exhibited excellent catalytic activities in the selective reduction of nitroarenes and Suzuki cross-coupling reactions. The catalysts could be easily separated by a magnet, and recycled consecutively.
Catalytic reduction of CO2 requires active, selective and low-cost catalysts. Results of this study show that transition metal carbides are a class of promising catalysts and their activity is correlated with oxygen binding energy and reducibility as shown by DFT calculations and in situ measurements.
The objective of this research is an in-depth exploration of semiconductor photo-catalysts that are able to convert CO2 and H2O and sunlight to energy rich and transportable fuels, such as CH4, CH3OH and HCO2H. The main focus is on the synthesis, structure determination, physical property characterization and photocatalytic testing of different classes of semiconductor photo-catalysts, with and...
In the field of catalysis, it is highly desired to develop novel catalysts that combine the advantages of both homogeneous and heterogeneous catalysts. Here we disclose that the use of plant polyphenol as amphiphilic large molecule ligand/stabilizer allows for the preparation of noble metal complex and noble metal nanoparticle catalysts. These catalysts are found to be highly selective and acti...
In this paper, xCuO/CeO2–γAl2O3 nano-catalysts were successfully synthesized by precipitation from an aqueous solution which modified via ultrasonic waves. For characterization of xCuO/CeO2–γAl2O3 samples N2 adsorption results showed that the BET surface area of the CuO/CeO2–γAl2O3, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-rays (EDX dot-mapping) were u...
The vapour phase selective conversion of glycerol to acetol at normal atmospheric pressure in a fixed-bed micro reactor was investigated over SO4 2 and WOx promoted ZrO2 and M-ZrO2 (M = Al2O3 or TiO2) solid acid catalysts. The investigated sulfate and tungstate ion promoted zirconia-based catalysts were prepared by both coprecipitation and impregnation methods and calcined at 923 K. The synthes...
Methylcyclohexane (MCH)-toluene (TOL) chemical hydride cycles as hydrogen carrier systems are successful with the selective dehydrogenation of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.
The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of ze...
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