نتایج جستجو برای: silver catalyst
تعداد نتایج: 89016 فیلتر نتایج به سال:
oxidation of ethylene to ethylene oxide over silver catalyst and selenium modified catalyst has been studied by continuous flow and pulse techniques over the temperature range of 230-280 °c. the results are discussed in terms of reaction mechanisms proposed by others, rejecting mechanisms which involve peroxide formation. it has been shown that not only selectivity towards ethylene oxide produc...
The properties of silver in the oxidative dehydrogenation of methanol were studied in a flow reactor under near industrial conditions. The influences of temperature, concentration of both reactants, gas velocity, space velocity, the form of the silver catalyst and surface composition of the catalyst were studied. A model for the reaction is proposed which is based on the experimental observatio...
The mechanisms responsible for spontaneous silver precipitation in silver-doped sol-gel materials are identified. The chemistry of the solvent phase is found to be the critical factor in controlling this phenomenon. The addition of HCl as catalyst leads to the formation of AgCl and subsequent formation of silver upon light exposure. Another factor leading to silver precipitation is the reducing...
The mechanisms responsible for spontaneous silver precipitation in silver-doped sol-gel materials are identified. The chemistry of the solvent phase is found to be the critical factor in controlling this phenomenon. The addition of HCl as catalyst leads to the formation of AgCl and subsequent formation of silver upon light exposure. Another factor leading to silver precipitation is the reducing...
The decontamination reactions of O,S-diethyl methyl phosphonothiolate, as an agricultural organophosphorous pesticide onto 20 wt% loaded manganese dioxide nanoparticles-silver-Y zeolite as a nanocomposite catalyst in different solvents, were evaluated and monitored by means of gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. Prior to the reaction, the catal...
A library of 1,2,3-triazoles was synthesized from diverse alkynes and azides using catalytic amounts of silver chloride instead of copper compounds. In addition, a novel "abnormal" silver N-heterocyclic carbene complex was tested as catalyst in this process. The results suggest that the reaction requires only 0.5% of silver complex, affording 1,2,3-triazoles in good yields.
The silver-catalyzed, oxidative coupling of methane to C2 hydrocarbons (OCM) is shown to be an extremely structure-sensitive reaction. Reaction-induced changes in the silver morphology lead to changes in the nature and extent of formation of various bulk and surface -terminating crystal structures. This, in-turn, impacts the adsorption properties and diffusivity of oxygen in silver which is nec...
Silver-catalyzed tandem acetalization and cycloisomerization reactions were found to lead to various furoquinolines, and a nitrogen effect was noticed for AgOTf reactivity, since the cyclization mode switched from 6-endo-dig to 5-exo-dig; from these observations silver imidazolate polymer is proposed as a stable silver catalyst.
We report on a stabilization effect on the structure and activity of Ag/Al2O3 for the selective catalytic reduction (SCR) of NOxwith CH4 imparted by the presence of SO2 in the exhaust gasmixture. The reaction is carried out at temperature above 600 8C to keep the surface partially free of sulfates. In SO2-free gases, catalyst deactivation is fast and measurable at these temperatures. Time-resol...
Oxidation of ethylene to ethylene oxide over silver catalyst and selenium modified catalyst has been studied by continuous flow and pulse techniques over the temperature range of 230-280 °C. The results are discussed in terms of reaction mechanisms proposed by others, rejecting mechanisms which involve peroxide formation. It has been shown that not only selectivity towards ethylene oxide pr...
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