نتایج جستجو برای: catalyst deactivation

تعداد نتایج: 49789  

Journal: :Chemical science 2015
James J Devery Iii James J Douglas John D Nguyen Kevin P Cole Robert A Flowers Ii Corey R J Stephenson

Knowledge of the kinetic behavior of catalysts under synthetically relevant conditions is vital for the efficient use of compounds that mediate important transformations regardless of their composition or driving force. In particular, these data are of great importance to add perspective to the growing number of applications of photoactive transition metal complexes. Here we present kinetic, sy...

Journal: :Nanoscale 2013
Longfei Wu Hongbin Feng Mengjia Liu Kaixiang Zhang Jinghong Li

A facile and straightforward approach is developed for the construction of graphene-based hollow spheres. An electron rich sodium-ammonia solution is used to effectively restore the π-conjugation of graphene. The hollow spheres exhibit excellent electrocatalytic activity towards oxygen reduction without catalyst deactivation.

Journal: :Organic letters 2014
Kevin Lafaye Lionel Nicolas Amandine Guérinot Sébastien Reymond Janine Cossy

Cross-metathesis involving N-heteroaromatic olefinic derivatives is disclosed. The introduction of an appropriate substituent on the heteroaromatic ring decreases the Lewis basicity of the nitrogen atom, thus preventing the deactivation of the ruthenium-centered catalyst. The reaction is quite general in terms of both N-heterocycles and olefinic partners.

An empirical rate equation was obtained for the methanation kinetics catalyzed by MCR-2X, a commercial catalyst prepared by Haldor-Topsoe. The studies were carried out in a fixed-bed reactor under differential conditions, and in a gradientless recycle reactor (Berry) over a range of total pressures, reactant concentractions (H2/CO ratios), and temperatures. The kinetics of methanation were foun...

Abbas Ali Khodadadi Ahmad Tavasoli, Kambiz Sadaghiani Yadollah Mortazavi

In a novel dual bed reactor Fischer-Tropsch synthesis was studied by using two diffrent cobalt catalysts. An alkali-promoted cobalt catalyst was used in the first bed of a fixed-bed reactor followed by a Rutenuim promoted cobalt catalyst in the second bed. The activity, product selectivity and accelerated deactivation of the system were assessed and compared with a conventional single bed r...

Journal: :Sustainable Energy and Fuels 2022

The strong Brønsted and Lewis acid sites are active in the tandem conversion of levulinic into ethyl valerate. intrinsic activity former is more significant Pd/HBEA catalyst deactivation partially reversible by calcination.

2003
E. FLASCHEL

-Feeding continuously operated stirred tank rectors with reactants and homogeneous catalysts subject to inactivation will usually lead to a limited substrate conversion with increasing space time. However, it is shown that a maximum of conversion may be observed under certain circumstances. Guided by experimental evidence, the theoretical background is discussed for identifying reaction systems...

Journal: :Molecules 2017
Andrey A Gusev Antonios C Psarras Konstantinos S Triantafyllidis Angelos A Lappas Paul A Diddams

ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC) process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam), FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-...

2009
X. She M. Flytzani-Stephanopoulos C. Wang Y. Wang C.H.F. Peden

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...

2017
Siddharth Gadkari Beatriz Fidalgo Sai Gu

A comprehensive 3D coupled mathematical model is developed to study the microwave assisted thermocatalytic decomposition of methane with activated carbon as the catalyst. A simple reaction kinetic model for methane conversion (accounting for catalyst deactivation) is developed from previously published experimental data and coupled with the governing equations for the microwaves, heat transfer,...

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