ISSN:
1572-879X
Keywords:
iridium
;
tin
;
NaY
;
alkane dehydrogenation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Zeolite-NaY-supported Ir/Sn catalysts (1 wt% Ir, 0.6 wt% Sn; 1:1 molar ratio) were prepared by adsorption of the organometallic precursors Ir(CO)2(acac) and SnMe3OH or (COD)2Ir–SnMe3 {COD= 1,5-cyclooctadiene) from hexane solutions followed by activation in H2 up to 773 K. The Ir/Sn/NaY catalysts displayed high selectivity for the dehydrogenation of propane to propene at ca. 773 K and, in the presence of H2, maintained thermodynamic conversion levels for up to 24 h. After activation, the catalyst derived from the dual-source precursors ({Ir+Sn/NaY) appeared homogeneous in composition, whereas the catalyst derived from the single-source precursor (Ir–Sn/NaY) appeared heterogeneous with distinct regions of visible particles. Scanning transmission electron microscopy revealed that the nanoscale metal particles present were small and uniform in size (ca. 1 nm) in the Ir + Sn/NaY catalyst but ranged in size from 1 to 10 nm in the Ir–Sn/NaY catalyst. Energy-dispersive X-ray analysis showed that bimetallic particles were formed for both catalysts. Temperature-programmed reaction of chemiosorbed carbon monoxide indicated that the Ir/Sn/NaY catalysts were electronically modified by the presence of tin in comparison with analogously prepared Ir/NaY catalysts.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1019056411553
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