ISSN:
1572-879X
Keywords:
EXAFS
;
XANES
;
methanol synthesis catalysts
;
Cu/ZnO
;
Cu/ZnO-Al2O3
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Cu K-absorption edge and EXAFS measurements on binary Cu/ZnO and ternary Cu/ ZnO-Al2O3 catalysts of varying compositions on reduction with hydrogen at 523 K, show the presence of Cu microclusters and a species of Cu1+ dissolved in ZnO apart from metallic Cu and Cu2O. The proportions of different phases critically depend on the heating rate especially for catalysts of higher Cu content. Accordingly, hydrogen reduction with a heating rate of 10 K/min predominantly yields the metal species (〉50%), while a slower heating rate of 0.8 K/min enhances the proportion of the Cu1+ species (∼ 60%). Reduced Cu/ZnO-Al2O3 catalysts show the presence of metallic Cu (upto 20%) mostly in the form of microclusters and Cu1+ in ZnO as the major phase (∼ 60%). The addition of alumina to the Cu/ZnO catalyst seems to favour the formation of Cu1+/ZnO species.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00769298
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