| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 40894 | Applied Catalysis A: General | 2012 | 8 Pages |
The increasing need for shifting to renewable feedstocks in the chemical industry has driven research toward using green aerobic, selective oxidation reactions to produce bulk chemicals. Here, we report the use of a ruthenium mixed oxide/hydroxide (RuOx) on different support materials for the selective aerobic oxidation of ethanol to acetic acid. The RuOx was deposited onto different oxide supports using a new gas-phase reaction, which in all cases resulted in homogeneous nanoparticulate films. The RuOx particle size ranged from 0.3 to 1.5 nm. The catalytic activity was evaluated on TiO2, Mg6Al2(CO3)(OH)16 · 4(H2O), MgAl2O4, Na2Ti6O13 nanotubes, ZnO, γ-Al2O3, WO3, CeO2, and Ce0.5Zr0.5O2 supports. The CeO2 supported RuOx had the highest activity, and selectivity toward acetic acid, of all the materials when normalized with respect to Ru-loading. This high activity was independent of the surface area of the support and the loading of RuOx under the tested conditions. This was attributed to the highly uniform size of the RuOx deposits, demonstrating that the deposition is suitable for producing small nanoparticles at high loadings. To elucidate the reason for the promotional effect of CeO2, Ce0.5Zr0.5O2 was investigated as a high oxygen storage capacity support, however, this did not result in higher catalytic activity. The high activity of CeO2 supports compared to the low activity ZnO appear correlated to the presence of high valence Ru(VI) species analogous to that observed in literature.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (129 K)Download as PowerPoint slideHighlights► The RuOx are highly dispersed and narrow sized regardless the support and loading. ► The RuOx is active and selective for the aerobic oxidation of ethanol to acetic acid. ► RuOx on CeO2 is the most active catalyst for the aerobic oxidation of ethanol to acetic acid. ► The RuOx activity is attributed to the presence of high valence Ru(VI). ► The effect of heat-treatment on the catalytic activity is investigated.
