Transient kinetic analysis

Burch, R., Shestov, A.A. and Sullivan, J.A. (1999) A steady-state isotopic transient kinetic analysis of the N0/02/H2 reaction over Pt/Si02 catalysts, J. Catal. 188, 69. 

Rothaemel, M., Hanssen, K.F., Blekkan, E.A., Schanke, D., and Holmen, A. 1997. The effect of water on cobalt Fischer-Tropsch catalysts studied by steady-state isotopic transient kinetic analysis (SSITKA). Catal. Today 38 79-84. 

In this contribution, the steady-state isotopic transient kinetic analysis-diffuse reflectance Fourier transform spectroscopy (SSITKA-DRIFTS) method provides further support to the conclusion that not only are infrared active formates likely intermediates in the water-gas shift (WGS) reaction, in agreement with the mechanism proposed by Shido and Iwasawa for Rh/ceria, but designing catalysts based on formate C-H bond weakening can lead to significantly higher... 

During steady-state isotopic transient kinetic analysis, the 12CO was switched to 13CO and the carbon-containing adsorbed and gas phase species were monitored in the IR as they exchanged from the 12C to the 13C label. Particular attention was made to those species that exchanged on a timescale similar to that of the exchange of the product C02, as that species could be a likely intermediate to the water-gas... 

Ocal, M Oukaci, R Marcelin, G. Steady state isotopic transient kinetic analysis (SSITKA) investigation of NO reduetion with CO over perovskite eatalysts. Ind.Eng. Chem. Res., 1994, Volume 33, 2930-2934. 

Schaertl, S. Konrad, M. Geeves, M.A. Substrate specificity of human nucleoside-diphosphate kinase revealed by transient kinetic analysis. J. Biol. Chem., 273, 5662-5669 (1998)... 

Considerable progress has recently been made in developing the theoretical background necessary for the application of the above method of transient kinetic analysis. An important step in this direction was the use of WKB asymptotics to derive approximate analytical expressions for short- and long-time transient sorption and permeation in membranes characterized by concentration-independent continuous S(X) and Dt(X) functions 150-154). The earlier papers dealing with this subject152 154) are referred to in a recent review 9). The more recent articles 1S0 1S1) provide the correct asymptotic expressions applicable to all kinetic regimes listed above the usefulness... 

Coluccio, L. M., and Geeves, M. A. (1999). Transient kinetic analysis of the 130-kDa myosin I (MYR-1 gene product) from rat liver. A myosin I designed for maintenance of tension /. Biol. Chem. 274, 21575-21580. 

Kurzawa-Goertz, S. E., Perreault-Micale, C. L., Trybus, K. M., Szent-Gyorgyi, A. G., and Geeves, M. A. (1998). Loop I can modulate ADP affinity, ATPase activity, and motility of different scallop myosins. Transient kinetic analysis of SI isoforms. 

Unlike the standard protocols for steady-state kinetic analysis, transient kinetic analysis is dependent on the availability of signals to measure individual steps of the reaction. Moreover, the observable kinetics change and can be complex or deceivingly simple depending on the relative magnitudes of sequential steps in a pathway. The rule of thumb is that one exponential phase exists in the time dependence of a reaction for each step in the pathway. For example, the kinetics of signals observable according to Scheme 2 will follow a triple exponential function Y =Ai e A- + A2 - A3 -f c. Moreover,... 

Figure 4.3.1a shows a schematic of an apparatus to perform the steady-state, isotopic transient kinetic analysis for the hydrogenolysis of ethane over a Ru/Si02 catalysis ... 

Steady-state isotopic transient kinetic analysis can determine the concentration and relative strength distribution of active sites. 

Buyevskaya et al, 1994 Mallens et al, 1994) and SSITKA (Steady-State Isotopic Transient Kinetic Analysis) (Nibbelke et al, 1995) techniques. It was demonstrated that ethane—the primary OCM product—is leaving the reactor with the same characteristic time as an inert tracer. This surely indicates that no intermediates noticeably residing on the surface participate in its formation. 

Kinetics and diffusion Steady-state isotopic transient kinetic analysis (SSITKA) Temporal analysis of products (TAP) Tapered element oscillating microbalance (TEOM) Temperature scanning reactor (TSR) Zero length chromatography (ZLC) Pulsed field gradient NMR... 

The model for a—j3 intersubunit communication indicates that it is the formation of the aminoacrylate species that leads to activation of the a reaction. When both serine and IGP are added simultaneously to the enzyme in a single enzyme turnover experiment, there is a lag in the cleavage of IGP that is a function of the reaction of serine to form the aminoacrylate species. Accordingly, amino acids other than serine that can undergo dehydration to form the aminoacrylate such as cysteine should serve as alternate substrates but should lead to a longer lag for the a subunit activation as determined by transient kinetic analysis. Cysteine does... 

A large amount of N2O was formed from the initial stage over LaM03 (M = Co, Mn, Fe, Cr, Ni) at 573 K. The time course of the NO+CO reaction (performed in a batch recirculation system) reflects this situation. These results support a two-step reaction pathway in which N2O is an intermediate for nitrogen formation, deal et al. (1994) confirm the role of N2O as intermediate in this reaction over perovskite oxides. They used steady-state isotopic transient kinetic analysis to study the mechanism of NO + CO reaction over LaCo03. They concluded that N2O was an intermediate in the formation of N2 at T < 873 K. They also concluded that at high temperature CO2 desorption became the rate-limiting step of the overall reaction. This is likely due to the rapid formation and slow decomposition of very stable carbonates on the perovskite surface as reported by Milt et al. (1996). 

Steady-state isotopic transient kinetic analysis (SSITKA) involves the replacement of a reactant by its isotopically labelled counterpart, typically in the form of a step or pulse input function. Producing an input function with isotope-labelled reactants permits the monitoring of isotopic transient responses, while maintaining the total concentration of labelled plus nonlabelled reactants, adsorbates, and products at steady-state conditions. It is assumed that there are no effects due to differences in kinetic behavior of the isotopic species from unmarked atomic species. However, for instance, deuterium substitution exhibits isotopic effects that can not be neglected. 

In SSITKA (steady-state isotopic transient kinetic analysis) developed and actively applied by Happel, Biloen and Goodwin, it is common to consider the catalyst surface to be composed of a system of interconnected pools, also termed compartments, where each pool represents a homogeneous or well-mixed subsystem within the reaction pathway. 

In the present communication we report on the influence of water on the FT synthesis studied by SSITKA and conventional kinetic experiments. Steady-state isotopic transient kinetic analysis (SSITKA) has proved to be a powerful technique for this work. The technique involves switching between CO and " CO in the feed gas and analyzing the transients with respect to the formation of products containing C and C. This technique allows the determination of the true turnover frequency of the active site, decoupled from site coverage. Applied to the FTS over metal promoted cobalt catalysts SSITKA has shown that the true turnover frequency of cobalt always remains the same, regardless of the second metal [6-8]. 

Steady-state isotopic transient kinetic analysis (SSITKA) shows that the deactivation of the methanation reaction after water treatment is due to a decrease in the number of active sites, while the intrinsic site activity apparently remains unchanged. 

From the transient kinetic analysis [8] we obtained the kinetic parameters and the quantity of H2 D2) which spilt over from the Ni surface to the oxide surface. 

The transient kinetic analysis of the isotopic exchange H/D is a direct and useful method to investigate the transformation of the catalytic surfaces under different reaction conditions. These experiments prove that there is a strong variation among the OH population over the oxides in the hydrogen stream zis a function of the temperature and of the nature of the oxidic support of Ni catalysts. 

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