ISSN:
1573-9171
Keywords:
dehydrogenation
;
dodecane
;
IR spectroscopy
;
rhenium
;
technetium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The state of Re and Tc in low-percentage alumina-rhenium (0.25 % Re) and aluminatechnetium (0.1 % Tc) catalysts reduced by H2 at 500–900 °C was studied using IR spectra of the diffuse reflection of the adsorbed CO. A highly dispersed (probably two-dimensional) metal phase with a lowered electron-donating ability due to strong metal—support interaction is present on the surface of these catalysts along with the ionic forms of Re and Tc at +1 and +4 oxidation states. CO adsorbed on such metals in a linear form can be removed by evacuation even at ∼20°C. The amount of highly dispersed metal phase on the support surface increases monotonically with an increase in the activation temperature of Re/Al2O3 and Tc/Al2O3. The activity of the catalysts in the dehydrogenation ofn-dodecane varies directly with the concentration of the electron-deficient highly dispersed metal phase. It is therefore concluded that highly dispersed Re0 and Tc0 formed during high-temperature treatment by H2 are the precursors of the catalytically active centers in the paraffin dehydrogenation reaction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00703992
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