High efficiency CoSn/ZnO catalysts for the hydrogenation of methyl oleate

The hydrogenation of methyl oleate (methyl cis-9-octadecenoate) to oleyl alcohol (methyl cis-9-octadecen-1-ol) was studied in the presence of a bimetallic CoSn supported over zinc oxide catalyst in a stainless steel batch reactor at 270 °C and 8.0 MPa of hydrogen. The active species in the reduction of methyl oleate into unsaturated alcohols was CoSn2. In order to increase the amount of these active species the nature of the precursor salts was studied. These results have shown that the carbonyl cobalt precursor is the optimum salt for the hydrogenation of methyl oleate into unsaturated alcohol since the selectivity to unsaturated alcohol reached 55% at 80% of conversion. Moreover, the selectivity is governed by the reduction of the heavy esters (oleyl oleate and oleyl stearate) formed, which can occur in the presence of small Co–Sn2 particles, well dispersed on the catalyst surface and with a high surface content.

Herein, we reported that CoSn/ZnO prepared from cobalt carbonyl with a Sn/Co surface ratio of 2 leads to the formation of alcohols with a yield of 70% at 270 °C at 8 MPa, after 26 h. This catalyst allows the formation of unsaturated alcohols with yield comparable to Ru catalyst. These results have shown that the formation of unsaturated alcohols is correlated to the hydrogenation of heavy esters (products of the transesterification reaction).Figure optionsDownload high-quality image (136 K)Download as PowerPoint slideHighlights
► 70% of alcohols obtained from the hydrogenation of methyl oleate at 270 °C under 8MPa of H2.
► High efficiency of CoSn/ZnO prepared with carbonyl salts.
► Active species: CoSn2 well dispersed with a small particle size.
► Necessary to control the secondary reaction of transesterification.