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Use of CO/sub 2//CO gas mixtures to study adsorption on chromia-promoted magnetite at water-gas shift temperatures

Journal Article · · J. Catal.; (United States)
OSTI ID:6277705

The adsorption of CO and CO/sub 2/ on chromia-promoted magnetite was studied volumetrically at temperatures near 650 K using CO/sub 2//CO gas mixtures in which magnetite is the thermodynamically stable form of iron oxide. Specifically, studies were conducted (i) at 637 K using CO/sub 2//CO gas mixtures with partial pressure ratios, P/sub CO/sub 2///P/sub CO/, equal to 5.45, 2.37, and 1.56, and (ii) at 613, 637, and 663 K using a CO/sub 2//CO gas mixture with P/sub CO/sub 2///P/sub CO/ equal to 5.45. By measuring the changes in total pressure and gas composition when a known dose of gas mixture was exposed to the sample, the individual surface coverages by CO and CO/sub 2/ were determined. At constant temperature and P/sub CO/, the surface coverage by CO was found to decrease with increasing P/sub CO/sub 2//; and, at constant temperature and P/sub CO/sub 2//, the surface coverage by CO/sub 2/ was found to decrease with increasing P/sub CO/. These data could be fit by either a one-site or a two-site model. In the first modr spectra of CO adsorbed on these Pd surfaces, and with recent results in the literature on CO hydrogenation. This model involves no assumptions regarding CO coverage, and assumes CH/sub 4/ forms from surface carbon produced by a hnsities on the Pd/TiO/sub 2/ catalysts, even at 300 K. The effect of Pd on the activity of CuO.

Research Organization:
Univ. of Wisconsin, Madison
OSTI ID:
6277705
Journal Information:
J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 71:1; ISSN JCTLA
Country of Publication:
United States
Language:
English