ISSN:
1572-879X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract [Al]-, [Ga]- and [Fe]-HZSM-5 having closely similar Brønsted acid site densities were prepared. The low-temperature adsorption of H2 and D2 was studied by FTIR spectroscopy and the frequency shifts ΔνOH and ΔνHH (ΔνDD) were measured and compared with corresponding frequency shifts observed for CO and N2 probes. A linear correlation between |ΔνOH|1/2 which is proportional to the heat of formation &/Delta;HB of the H-bonded complex O-H···B (B representing the H-bond acceptor), and the proton affinities of the three probe molecules was found for [Al]-HZSM-5. The ΔνOH-values measured for CO and H2 (D2) on the three isomorphously substituted zeolites suggested the following acid strength ranking: [Al]-HZSM-5 〉 [Ga]-HZSM-5 ≈ [Fe]-HZSM-5. This sequence is clearly reflected in the relative activities of the materials for the acid-catalyzed disproportionation of ethylbenzene.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1019086722262
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