Use of supported rhodium and cobalt carbonyls as catalysts for the CO + H2 reaction

The use of cobalt and rhodium catalysts derived from carbonyl clusters and supported on Al2O3, Al2O3\u2013ZnO, ZrO2 and SiO2 for the CO + H2 reaction has been investigated. Only Rh-containing catalysts were active in the formation of oxygenated compounds (essentially ethanol). In all the runs the selectivity to methane plus ethanol was > 90%. The ratios of the rates of ethanol and methane formation or the rate of ethanol formation and the CO reaction reach a maximum when equal amounts of Rh and Co are present on the catalyst surface. Cobalt alone does not form oxygenates, but when mixed with rhodium it increases the selectivity to ethanol

Behavior of chromium oxide on MgO or MgF2

The molecular structure and oxidation state of the chromium oxide on MgO or MgF2 as a function of Cr loading were determined by XRD, Raman spectroscopy, and XPS. The effects of preparation method and the acidity of support were investigated. The Raman study on a series of chromium oxide supported on MgO prepared by an impregnation method showed that the chromium oxide was present as polychromate independent of Cr loading due to high acidity of the preparation solution. In samples prepared by a precipitation method, the chromium oxide was present as monochromate at 5% Cr loading, as dichromate at 10% Cr loading, and as mono- and polychromate at 20% Cr loading due to a larger surface area of the support prepared by this method. The chromium in CrO3/MgF2 was present as polychromate and monochromate for impregnated and precipitated samples, respectively. The oxidation state of Cr(VI) on MgO is maintained independent of Cr loadings. When the 10 wt % Cr/MgO was calcined at 800 degrees C, MgCr2O4 and Cr2O3 were formed. Preferred formation of MgCr2O4 was observed for the precipitated sample due to its larger surface area compared to that of the impregnated sampleclose19191