Models kinetic, from surface science data

This example illustrates how the parameters of interest are derived from kinetic measurements. Of course, one should have ensured that the data are free from diffusion limitations and represent the intrinsic reaction kinetics. The data, reported by Borgna, that we used here satisfy these requirements, as the catalyst was actually a nonporous surface science model applied to a batch reactor. 

Microkinetic modeling assembles molecular-level information obtained from quantum chemical calculations, atomistic simulations and experiments to quantify the kinetic behavior at given reaction conditions on a particular catalyst surface. In a postulated reaction mechanism the rate parameters are specified for each elementary reaction. For instance adsorption preexponential terms, which are in units of cm3 mol"1 s"1, have been typically assigned the values of the standard collision number (1013 cm3 mol"1 s 1). The pre-exponential term (cm 2 mol s 1) of the bimolecular surface reaction in case of immobile or moble transition state is 1021. The same number holds for the bimolecular surface reaction between one mobile and one immobile adsorbate producing an immobile transition state. However, often parameters must still be fitted to experimental data, and this limits the predictive capability that microkinetic modeling inherently offers. A detailed account of microkinetic modelling is provided by P. Stoltze, Progress in Surface Science, 65 (2000) 65-150. 

In summary, DFT calculation and microkinetic analysis-based macrokinetic modeling method is very helpful to understand the DHP chemistry and establish kinetic models with theoretical basis. But some discrepancy stiU exists between the experiments and the predictions based solely on energies determined by DFT calculations. For DHP, more data from theoretical calculation, surface science and kinetic experiments stiU need to be gathered for a more comprehensive microkinetic analysis and a more in-depth understanding of the kinetic behavior. With the development of nanotechnology, nanoparticles with specific structure properties can be routinely synthesized, which are ideal materials to probe the reaction... 

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