THE ROLE OF MN AND LI PROMOTERS IN SUPPORTED RHODIUM CATALYSTS IN THEFORMATION OF ACETIC-ACID AND ACETALDEHYDE

Rh-Mn-Li/SiO2 catalysts consisting of 1 wt% Rh for the synthesis of C- 2 oxygenates from syngas were studied by CO + H-2 reaction and charact erized by TPR, H-2-TPD, ESR and IR techniques. The Rh-Mn-Li/SiO2 catal ysts, which showed a good selectivity for the formation of acetic acid and acetaldehyde, have been found to be quite different from the Rh-V /SiO2 catalysts reported previously, which mainly promoted the formati on of ethanol. Comparing with the Rh-V/SiO2 catalysts, the Rh-Mn-Li/Si O2 exhibited lower capacity of hydrogen adsorption, lower hydrogenatio n activity, more intense interaction of the manganese oxide with the R h component, and more intense bands of twin-adsorbed CO (i.e. more Rh1 + ion). The good selectivity of the Rh-Mn-Li/SiO2 catalysts towards ac etaldehyde and acetic acid formation were correlated to these features . (C) 1997 Elsevier Science B.V.