Isotopic 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. 

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... 

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. 

S.H. Ali and J.G. Goodwin, Jr., Impact of Readsorption Effects and Their Removal from Surface Reaction Parameters Obtained by Isotopic Transient Kinetic Analysis Methanol Synthesis on Pd/SiOa, J. of Catalysis 171, 339-344 (1997). 

J.U. Nwalor, JG. Goodwin, Jr., and P. Biloen, Steady-State Isotopic Transient Kinetic Analysis of Iron-Catalyzed Ammonia Synthesis, J. of Catalysis 117, 121 (1989). 

J.U. Nwalor, Isotopic Transient Kinetic Analysis of Ammonia Synthesis Catalysis. Ph.D. Dissertation, University of Pittsburgh, Pittsburgh, 1988. 

Steady state isotopic transient kinetic analysis is a powerful technique for in situ analysis of heterogeneous catal dic reactions. It provides information... 

Oukaci R, Blackmond DG, Goodwin JG, Jr, Gallaher G, Steady-state isotopic transient kinetic analysis investigation of CO-O2 and GO-NO reaction over a commercial automotive catalyst, in Silver RG, Sawyer JE, Summers JG (eds.). Catalytic Control of Air Pollution Mobile and Stationary Sources, Washington, DG, 1992. 

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