Titanium-Promoted Rh-Mn-Li/SiO2 for C2-Oxygenates Synthesis from Syngas: Effect of Low Titanium Load

Addition of small amounts of Ti oxide to Rh-Mn-Li/SiO2 catalysts unexpectedly results in an increase in their activity for C2-oxygenates production from syngas. Continuously increasing Ti loading depresses catalyst activity. The effect of Ti at low level on the catalytic properties in the CO/H2 reaction has been studied by various techniques. The characterization results indicate that the existence of Ti species has no effect on the ability of Rh to dissociate CO molecules and on the Rh dispersion. On the other hand, it is shown that trace amount of Ti strengthens the adsorption of CO and increases the amount of strongly adsorbed CO that can be hydrogenated and therefore improves the activity. The RhMn interaction intensity, which can be regulated by Ti doping, seems to be the main reason to achieve higher yield of the desired reaction products.