نتایج جستجو برای: catalyst selectivity
تعداد نتایج: 86617 فیلتر نتایج به سال:
Oxidative coupling of methane (OCM) is a promising method for the direct conversion of methane to ethene and ethane (C2 products). Among the catalysts reported previously, Mn2O3-Na2WO4/SiO2 showed the highest conversion and selectivity, but only at 800° to 900°C, which represents a substantial challenge for commercialization. We report a TiO2-doped Mn2O3-Na2WO4/SiO2 catalyst by using Ti-MWW zeo...
2 Introduction 3 Results and Discussion 17 A Chromium Diphosphine System for Selective and Catalytic Ethylene Oligomerization 17 Synthesis of PNP Ligands with Ether Groups Tethered to Nitrogen 17 Preparation and Characterization of PNP Chromium Complexes 18 Catalytic Runs at 1 atm of Ethylene Using Precatalysts 21-24 24 Catalytic Runs at Higher Pressures of Ethylene 28 Role of the Ether Tether ...
The observed rate of reaction in the dysprosium triflate catalyzed aza-Piancatelli rearrangement is controlled by a key off-cycle binding between aniline and catalyst. Deconvoluting the role of these ancillary species greatly broadens our understanding of factors affecting the productive catalytic pathway. We demonstrate that the rate of reaction is controlled by initial competitive binding bet...
A process was developed to synthesize ruthenium-based chelate RuNx electrocatalysts for the oxygen reduction reaction, using RuCl3 and propylene diammine as the Ru and N precursors, respectively. High-temperature pyrolysis has a critical role in the formation of the catalytic Ru–N sites for oxygen reduction. The RuNx catalyst modified in the presence of nitrogen-containing organic exhibited com...
Thiourea (TU)/amine base cocatalysts are commonly employed for well-controlled, highly active "living" organocatalytic ring-opening polymerizations (ROPs) of cyclic esters and carbonates. In this work, several of the most active cocatalyst pairs are shown by 1H NMR binding studies to be highly associated in solution, dominating all other known noncovalent catalyst/reagent interactions during RO...
In-situ synthesis of a zeolite with encapsulated Pt was conducted to prepare a sulfur-resistant noble metal catalyst based on concepts of shape selectivity and hydrogen spillover. The prepared zeolite was of the sodalite type, in which the pore openings allow H2 to enter the pores but not H2S. Chemisorption with H2/CO was conducted to verify the most of Pt atoms distribution in the cage of Pt/S...
Efficient aerobic oxidative methyl esterification of primary alcohols has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate ...
A novel SBA-15-functionalized TEMPO confined ionic liquid [BMIm]Br was found to be a highly efficient and recyclable catalyst system for the transition-metal-free aerobic oxidation of a wide range of structurally diverse alcohols. Thanks to the strong physical confinement of the ionic liquid inside the mesochannels of SBA-15-supported TEMPO, the resulting solid catalyst showed improved selectiv...
In an earlier publication [1] it has been claimed that oxidative coupling of methane to higher hydrocarbons had been obtained with close to 100% selectivity at 600~ and atmospheric pressure in the presence of steam over a CaNiK oxide catalyst. These results have been confirmed in longer runs. Artifacts, such as carbonate formation on the catalyst, have been excluded. The reaction is slightly ex...
New supramolecular photocatalysts comprising an asymmetric bis-tridentate Ru(ii) complex that functions as a photosensitizer and a Ru(ii) carbonyl complex as the catalyst were designed. The complexes photocatalyzed the reduction of CO2 to CO or formic acid with high selectivity. The product distribution depended on the catalyst unit. CO and formic acid were the main products when using [Ru(BL)(...
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