Stoichiometric adsorption complexes in [B]- and [Fe]-ZSM-5 zeolites

• Published in: Journal of catalysis 1989, Vol.116 (1), p.252-262
• Main Authors: Kofke, T.J.Gricus, Gorte, R.J., Kokotailo, G.T.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-gas interface; Surface physical chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(89)90090-0

The adsorption of ammonia, 2-propanamine, and 2-propanol on H-[B]-ZSM-5 and H-[Fe]-ZSM-5 has been examined using temperature-programmed desorption (TPD) and thermogravimetric analysis (TGA) to investigate the effect of the incorporation of trivalent ions into the zeolite framework. For each of the adsorbates on H-[Fe]-ZSM-5, clearly defined adsorption complexes corresponding to one molecule/Fe atom could be identified. An adsorption complex with a stoichiometry of one molecule/B atom could also be observed for 2-propanamine on H-[B]-ZSM-5 but complexes were less clearly defined for ammonia and 2-propanol. The reactivity of these 1: 1 complexes indicates that the acid sites formed by the hydroxyls associated with B incorporation are much weaker than those associated with Fe or Al. We also examined a sample of ZSM-5 which had extraframework Fe using 2-propanamine adsorption and found that there was negligible adsorption due to these sites. These results indicate that TPDTGA measurements of selected adsorbates are valuable in characterizing the materials created by the incorporation of trivalent cations into the zeolite framework.