Some authors reported pulse chemisorption of CO on CeO2, but they said nothing about the conditions they used. But this kind of experiment is less obvious as it seems. What are the best conditions for observing the phenomenon by pulse chemisorption analysis coupled with TCD? I used several samples with different shapes of cerium oxide. Prior to the pulse chemisorption experiment (at 298K), the samples were reduced by a Ar/H2 (10%) mixture at 773K, and then were cooled down under pure He to 298K. A 0.68uL injection loop was used and the sample mass weight was 50mg. I could never observe chemisorption with the TCD detector all of the picks were desame. What could be the reason of this? Have I forgotten an important detail? Maybe any suggestions?
Thank you in advance.
I haven't carried out the analysis myself, but in our publication (on MnCeOx) we specify the conditions that were used: https://www.sciencedirect.com/science/article/abs/pii/S0926337317306586?via%3Dihub
Maybe you don't need the hydrogen reduction (as it is an oxide without nanoparticles) and you can try to slightly increase the chemisorption temperature. Hope this helps!
First, you need to determined at what condition the reduction will take place. So, I would suggest to perform H2-TPR to figure that out.
Second, I would suggest to increase the sample amount to at least 150 mg.
Third, you did not mention what is the CO concentration that you're using? I would suggest 5% CO/He.
You can also estimate how much CO is expected to adsorb based on the TPR curve and the sample amount, then adjust the experimental condition accordingly.
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