Dear Ahmed,

TPR and TPD are two different test for H2-uptake and CO2-uptake respectively. To the best of my Knowledge H2-TPR is determining the reduction, but CO2/NH3-TPD determines the Lewis Basicity/acidity of the catalyst. You can do TPR after TPD, I think seems no issue with it.

Dear Ahamed

I guess it is not prefered to do TPR-H2 uptake before your TPD analysis has been done for the same samples. Rather, you can make two set of samples for the TPR-H2 uptake and TPD- NH3/-acidic [CO2/- basic sites] separately. As from TPR-H2 uptake we end up with reduction sites results whereas the acidic sites quantification can be determined using TPD-NH3 technique.

Dear Ahamed,

TPR and TPD, both are different technique for material analysis. TPD use for total acidity (NH3 adsorption) or basicity (CO2 adsorption) analysis from room temperature to desired temp, on the basis of material stability. where as, TPR, used for find the suitable temperature for Metal oxide or metal chloride to metallic form in the presence of H2. So, it better analysis done separate with different set of materials.

The NH3/CO2-TPD will provide the total acidity/basicity of your material. If you perform the H2-TPR first you may change the surface properties of your material, and therefore the acidity/basicity may change. For instance, If you are reducing a metal oxide the probe molecules (CO2 or NH3) will be chemisorbed onto the metal surface. In other words, there is no prefered way, you must think on what features of your material you are studying.

I think our colleagues Imran Gaffar and Dr. Dinesh Gupta are exactly right. Except a question- what do you want to study by TPD - reduction of nickel oxides or adsorbtion( chemosorbtion) of hydrogen on activated metallic surface. In the first case you can do preadsorbtion at room temperature but un second case must do preadsorbtion at lower temperatures because in the case of Ni-H2 there are many adsorbed forms desorbtion peaks of which are at minus degree. Best regards

Thank you so much for all of you

TPR procedure could be considered as an "activation" of active sites involved in NH3 or CO2 adsorption. So, results will be different if you decide to do (or not) TPR first.

Best Regards

SAM

Thank you so much

Only one measurement should be preferred at one time otherwise results would be different.