as we know for solid acids, all are using pyridine as probe molecule to know the bronsted and lewis sites.
what are the probe molecule can be use for solid base catalyst and what is the IR range( wave number range).
Solid base catalysts can be identified by using deuteroro chloroform (CDCl3) FT-IR spectroscopy. At the formation of H bonds, deuterochloroform behaves as a typical acid. The strength of base site was determined by the band shift of the CD stretching vibrations that occurred under CDCl3 adsorption. The strength can be recalculated into the proton affinity (PA) scale using the formula (Paukshtis, 1992).
Here I am attaching the journal. The mentioned data is useful for your solid base catalysts.
thank for information, but need more specific. because Al2O3 acts as amphotaric nature i need pure solid base catalysts such as Layer double Hydroxides etc.
You are using aluminium trioxide as catalyst. it is amphoteric oxide. Pyridine FT-IR useful for bronsted and Lewis acidic sites. If your catalyst is solid base, The above mentioned journal useful.
Probe molecules for basic sites are acidic. The most common FTIR probe for these sites is CO2, but it has many limitations. alternatively you could use alcynes. I just sent you a document on the characterization of basicity by FTIR.
Please have a look at:
F. J. del Rey-Perez-Caballero, G. Poncelet, Micropor. Mesopor. Mater. 37 (2000) 313.
Pyrrole and CDCl3.
Changing the position of the band indicates the strength of adsorption.
Hi
yes you can use DRIFT-Pyridine and from the spectra, peaks at 1445 and 1623 are corresponding to strong Lewis acid and peak at 1488 is for both Lewis/Bronsted and peak at 1575 is for bronted
have a very good day
- Badges
- Science topic
- Similar topics
- Engineering
- Petroleum Engineering
- Gas