Catalytic upgrading of long-chain 1-alkene in synthetic fuels over shape-controlled cobalt oxide nanocrystals

To upgrade odd numbered α-olefins derived from FTS residues, the heterogeneous hydroformylation of 1-heptene as a model compound for odd numbered α-olefin was investigated. Single crystalline Co₃O₄ nano catalysts with different morphologies (cube and octahedron) were synthesized using a hydrothermal method and were applied to the reductive hydroformylation of 1-heptene. HRTEM and SEM analysis indicated that the cubic and octahedral Co₃O₄ predominantly exposed well-defined crystal planes of {100} and {111}, respectively. The Co₃O₄ octahedron catalyst with highly exposed {111} facets had higher activity for hydroformylation than the Co₃O₄ cube catalyst. The Co₃O₄ octahedron catalyst with a {111} surface was easily reduced to CoO at lower temperature. These reduced cobalt species can be converted into cobalt carbonyl and improved reactivity with carbon monoxide, hydrogen and olefin, leading to better catalytic performance for hydroformylation than Co₃O₄. On the other hand, the Co₃O₄ cube catalyst with the {100} surface only exhibited the isomerization of 1-heptene.