نتایج جستجو برای: alkali catalyst
تعداد نتایج: 60055 فیلتر نتایج به سال:
We herein describe a straight forward procedure to increase the performance of platinum-on-alumina catalysts in methanol steam reforming by applying an alkali hydroxide coating according to the "solid catalyst with ionic liquid layer" (SCILL) approach. We demonstrate by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption (TPD) studies that ...
Addition of Li, Na, K and Cs to a 1.5 wt% Rh/Al,O, catalyst resulted in a decrease of the hydrocarbon formation rate, while the methanol formation rate was almost unaffected. The overall result is an increased oxygenate selectivity at a decreased total activity. The oxo-selectivity increased in the order unpromoted < Li < Na< K < Cs. The results suggest that the main role of the alkali promoter...
The kinetics of catalyst deactivation and coke formation during dehydrogenation of propane over supported Pt–based catalysts and, in particular, the effect of alkali metal promoters on catalyst activity and stability were studied. The analysis of propane conversion data showed that there is an optimum level of alkali metal promoter loading for both catalyst activity and stability.A model ba...
The first addition of alcohols to carbodiimides catalyzed by transition-metal-free compounds employs 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and its alkali metal salts. Isoureas are obtained in short reaction times and high yields when TBDK is used as the catalyst. Control of the coordination sphere of potassium with exogenous chelating ligands, in combination with mechanistic DFT calculation...
Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.
The first π-coordination-catalyzed nucleophilic fluorination of unactivated aryl halides has been demonstrated. Chlorobenzene reacts with alkali metal fluorides (CsF, KF) in the presence of a Cp*Ru catalyst at 120-180 °C to give fluorobenzene.
Alkali metal monoalcoholates of 1,3-diols can be used as very effective catalysts in the Tishchenko reaction of 4-hydroxy-1,3-dioxanes to the corresponding monoesters of 1,3-diols. These catalysts are extremely efficient and fast compared to metal hydroxides commonly used. Thus, monoalcoholate catalysts give fast transesterification with the product ester. The loss in yield due to ester interch...
Zincian georgeite, an amorphous copper–zinc hydroxycarbonate, has been prepared by co-precipitation using acetate salts and ammonium carbonate. Incorporation of zinc into the georgeite phase and mild ageing conditions inhibits crystallisation into zincian malachite or aurichalcite. This zincian georgeite precursor was used to prepare a Cu/ZnO catalyst, which exhibits a superior performance to a...
Zincian georgeite, an amorphous copper-zinc hydroxycarbonate, has been prepared by co-precipitation using acetate salts and ammonium carbonate. Incorporation of zinc into the georgeite phase and mild ageing conditions inhibits crystallisation into zincian malachite or aurichalcite. This zincian georgeite precursor was used to prepare a Cu/ZnO catalyst, which exhibits a superior performance to a...
alkali and alkaline earth metals hydrogen sulfate catalyzed the one-pot three component condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions leading to 3,4-dihydropyrimidin-2(1h)-ones in high yields at 80 °c. our results showed that biginelli reaction not only is ph dependent, but the cation of catalyst plays an important role.
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