Deactivation studies

Catalysis Monitoring of preparation, activation, deactivation, study under working conditions Weckhuysen 2004" Jentoft 2009 "... 

Most PET or excited state deactivation studies have been performed in solution, although... 

Fig. 4.2 Deactivation study of 29 catalysts in the multi-chamber pellet reactor of Senkan et al. [26].

In recent years, these donor-acceptor correlations to the reaction mode [49], substituent effects to stabilize meta intermediates [50-52], exo/endo selectivity [53-55], kinetics by means of fluorescence study [56] and deuterium isotope effect [57,58], formation and deactivation studies of exciplex [59,60], influence of pressure [61], and theoretical calculations [62-64] have been extensively studied. 

Some initial, very short deactivation studies were carried out with a blend of straight run VGO and coker gas oil (CGO). The test conditions were P = 100 atm., LHSV - 2.25 h T = 200°C or 375°C, The products from these experiments were collected at an interval of 3 minutes from the beginning of each run. Each product sample was analyzed for sulfur and nitrogen and fractionated into aliphatics as well as mono-, di-, tri- and polyaromatic compounds. Further details in [6],... 

A. Parmaliana, F, FrusterL, G.A. Nesterov, E.A. Paukshtis and N. Giordano, Catalyst Deactivation, Studies in Surface Science and Catalysis, 34 (1987) 197. 

J. Barbier, Catalyst Deactivation, Studies in Surfaces Science and Catalysis, 34 (1987) 1. 

Fischer-Tropsch precipitated iron catalysts Deactivation studies... 

J R Mellor, The Water Gas Shift Reaction Deactivation Studies, PhD Thesis, University of Witwatersrand Johannes-berg, South Afnca, 1993... 

Theoretical and experimental results on deactivation have been summarized in two reviews by Butt (.1,2). Previous work of particular interest to the present study has been done by Blaum (3) who used a one-dimensional two-phase model to explore the dynamic behavior of a deactivating catalyst bed. Butt and cowotkers (b,5,6)have performed deactivation studies in a short tubular reactor for benzene hydrogenation for both adiabatic and nonadiabatic arrangements. They experimentally observed both the standing (6) and travelling (4) deactivation wave. Hlavacek... 

This ongoing study is divided into two parts (t) a kinetic Study of unsupported iron catalysts at 1 atm total pressure and (2) a deactivation study of monolith-supported iron catalyst at 10 atm total pressure. In both parts unpromoted and potassium-promoted catalysts are being studied to determine the effects of potassium on activity, selectivity and deactivation rates. 

The catalyst deactivation studies described here were carried out in 300 cm.. gas-sparged, stirred autoclaves and in a nominal 10 ton (CH30H)/day pilot-plant, bubble-column reactor. The details of the design and operation of these reactor systems have been reported elsewhere [refs. 4,5]. AH of the present studies were carried out with a feed gas that is referred to as "CO-Rich Gas , with a molar composition of H2 35%, CO-51 %, C02-13% and N2 1%- Its stoichiometric ratio, defined as H2/(CO+1.5002), is 0.5. A typical stoichiometric ratio for the feed to a conventional methanol reactor Is about 2.6, well on the H2-rich side of 2.0, the ratio tor exact stoichiometric equivalence. The feed concentrations of known poisons such as hydrogen sulfide, carbonyl sulfide, chlorine compounds, iron carbonyl and nickel carbonyl were below the limits of detection, 50 ppb, 50 ppb, 10 ppb, 50 ppb and 50 ppb, respectively. 

Shabaker JW, Simonetti DA, Cortright RD, Dumesic JA (2005) Sn-modified Ni catalysts for aqueous-phase reforming characterization and deactivation studies. J Catal 231 67... 

Zhang, Y., Xiong, G., Sheng, S., and Yang, W. Deactivation studies over Ni0/y-Al203 catalysts for partial oxidation of methane to syngas. Catalysis Today, 2000, 63, 517. 

To determine the deactivation kinetics, long-term deactivation studies at constant conditions and at different temperatures are required. In some cases, accelerated aging can be induced to reduce the time required for the experimental work, by either increasing the feed flow... 

Such an approach was used in a previous study by Duvenhage, et al. in 1994 [5]. These authors performed a series of deactivation studies on catalysts which were first used in an industrial fixed bed reactor at SASOL, then removed, under nitrogen, from sections along the bed, and transferred to microreactors for further study. Their results [5] showed that the activity lost at the front of a fixed bed is caused by S poisoning. However, downstream into the reactor, they observed a clear correlation between the loss in activity and an increase in magnetite concentration. Further, they observed that in the region of highest activity, the catalyst contained... 

Deactivation Studies of Ni/AliOy ZSM-5 Catalysts Effect of Nickel Incorporation... 

F. Mandani, Kinetic and Deactivation studies during catalytic dehydrogenation, PhD Thesis, University of Salford, England, 1991. 

Serrano DP, Betas JA, Guil-Lopez R (2009) H2 production from methane pyrolysis over commercial carbon catalysts kinetic and deactivation study. Int J Hydrogen Energ 34 4488-4494... 

Two types of deactivation studies may be distinguished those in which catalysts are doped with the catalyst poison and those in which the catalyst is deactivated by compounds present in flue gases. 

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