I have read that chemisorption can be used to deliberate on the dispersion of a particle over a catalyst, but I want to know if TPR results may be of help for the same objective.
No not really as in most cases the hydrogen(for TPR) can diffuse into the bulk of the particle whereas with CO, chemisorption occurs on the surface of the particles only. Given that dispersion is an indication of the ratio of surface sites relative to total metal content you need to selectively identify the surface sites. However, the different temperatures at which metals reduce in TPR can give you a rough idea about whether the particles are very small or very large as in the case with Pd where a beta-hydride decomposition peak is evident at around 85 C only in particles that are very large. TPR by itself though will not give you a clear value of dispersion. Hope that helps.
Temperature programmed methods such as TPR, TPO and TPD are used to determine relative ease of reduction, oxidation and desorption respectively.
Hydrogen and CO chemisorption are used to evaluate quantitatively the number of surface active sites. If you want to know dispersion you need also to know the metal content of your catalyst.
See an exemple of that in my profile:
Activated carbons doped with Pd nanoparticles for hydrogen storage
International Journal of Hydrogen Energy, Volume 37, Issue 6, March 2012, Pages 5072-5080
You cannot use TPR which is a bulk technique but you could try using TPD of H2. You should have a look at this general article on the characterization of heterogeneous catalysts (see p37 for an example)
http://s3.ceelantech.com/docs/TPDROarticle.pdf
It is not a common way to determine metal dispersion but it is worth trying !
Juliette
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