As not possible to distinguish Bronsted and Lewis acid sites by TPD-NH3. So, it can be reasonable to use TPD-pyridine and (Drift) IR-Pyridine additionally to NH3-TPD analysis.
There is an instrumental Setup with a combined TPD-IR-MS available. It was presented on the IZC in Moscow in 2013 by Dr. Kazuyuki Nakai (BEL Japan), I am not sure, if the data is published now, but looks very interesting.
I thinks i should do pyridine-FTIR or TPD-pyridine analysis. Thanks. . .
TPD of adsorbed amine (such as n-propyl-amine) would allow to measure the number of Brönsted sites. See R. Gorte's papers on this subject.
Dear Colleague Karimi,
You can also use TPD-Pyridine
1- The total number of acidic sites (sites. m-2) over each catalyst can be measured using the temperature programmed desorption of pyridine (TPD-pyridine) as the probe molecule. The details have been described in previous publication (attached).
The acidity populations over the surface of catalysts, under investigation, were measured thermogravimetrically using the adsorption of pyridine as probe molecule. Small portions (50mg) of each sample were pre-heated at 250°C for 2 h in air before the exposure to the probe molecule. 15-20 mg of pyridine–covered samples were subjected to TG analysis on heating up to 600°C (at 20°C/min heating rate) in dry N2 (flow rate = 40 ml/min). The mass loss due to desorption of pyridine from the acidic sites, was determined as a function of total surface acidity as sites.g-1cat.
2- To detect the Bronsted acidic sites, you can use 2,6-dimethylpyridine as a probe of the strength of Brønsted acid sites.
Finally if substracted the number of acidic sites from step 2 (Lewis +Bronsted) from step 1 (Bronsted only, you can get the number of lewis acidic sites
However, FTIR- Pyridine is only used to distinguish between the Lewis and Brønsted
Hope this helping
Have a very good day
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