نتایج جستجو برای: acidic catalyst
تعداد نتایج: 77393 فیلتر نتایج به سال:
Palladium has attracted significant attention as a catalyst or co-catalyst for many electrochemical reactions in energy conversion devices. We have studied stability of commercial Pd/C sample an acidic electrolyte by exposing it to accelerated stress test (AST) mimic potential spikes fuel cells and electrolyzers during start/stop events. AST consisted extensive rapid cycling (5000 cycles, 1 V/s...
Emissions of sulfur trioxide (SO3) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough to not cause opacity violations and acid deposition. Generally, a small fraction of sulfur (S) in coal is converted to SO3 in coal-fired combustion devices such as electric utility boilers. The emissions of SO3 from such a boiler depend on coal S conte...
Scientists engaged in heterogeneous catalysis often cite enzymes as their model catalysts. Enzymes can efficiently catalyze multistep processes that give various types of biomolecules. Remarkably, many enzymes combine two antagonistic catalytic functions, such as acid and base functions. Attracted by this challenge, several groups synthesized homogeneous catalysts that can successfully combine ...
The chemistry of 2-oxo-1,2,3,4-tetrahydropyrimidines began to develop toward the end of 1893 year, when the first representatives of this class compounds were reported by P. Biginelli. Despite prior reports of several really effective catalytic and non-catalytic approaches towards Biginelli-type products, an overwhelming number of new catalysts for the Biginelli reaction have been recently publ...
In this work, the ionic liquid triethylamine-bonded sulfonic acid {[Et3N–SO3H]Cl}, N,N-diethyl-N-sulfoethanammonium chloride was used as a green acidic homogeneous catalyst to synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones as two categories of heterocycles, from aldehyde, dicarbonyl compound and urea or thiourea throughout the one-pot three components cycloc...
In this research, a Brønsted acidic ionic liquid namely N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium chloride {[TMBSED][Cl]2} was employed as a highly efficient catalyst for the solvent-free production of some nitrogen- and oxygen-containing heterocyclic compounds including: (i) polyhydroquinolines (from arylaldehydes, dimedone, β-ketoesters and ammonium acetate), (ii) 3,4-dihyd...
N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium chloride ([TMBSED][Cl]2) was synthesized as an acidic ionic liquid and characterized using FT-IR, 1H and 13C NMR, mass spectroscopy, TG, DTG and DTA techniques. This ionic liquid was employed as efficient catalyst for the extremely facile and efficient synthesis of dihydropyrrol-2-ones and functionalized tetrahydropyridines. One-pot f...
Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with m...
The titanium dioxide (TiO(2)) photoassisted degradation of herbicide dinoseb has been examined in aqueous suspensions under UV light irradiation. The degradation kinetics were studied under various conditions such as substrate concentration, type of catalyst, catalyst dosage, pH, and light intensity as well as in presence of electron acceptors such as hydrogen peroxide, potassium bromate, and p...
In the present study, the reaction kinetics and dynamic modeling of a reactor for syngas transformation into dimethyl ether using a mixture of a metallic oxides (CuO, ZnO, and Al2O3) and an acidic component (γ-Al2O3) as the catalyst has been investigated. A combination of the Graaf kinetic model for methanol synthesis and the Bercic model for methanol dehydration was correlated with the experim...
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