Supported Cobalt Catalysts for Acceptorless Alcohol Dehydrogenation

The acceptor‐less dehydrogenation of 2‐octanol was tested over cobalt supported on Al 2 O 3 , C, ZnO, ZrO 2 and various TiO 2 substrates. The catalysts were characterized by ICP, XRD and TGA‐H 2 . For Co/TiO 2 P25, the effects of passivation, aging (storage at room temperature), and in situ activation under H 2 were investigated. The catalysts must be tested shortly after synthesis in order to prevent deactivation. Cobalt supported on TiO 2 P25 was the most active and 69 % yield of 2‐octanone was obtained, using decane as a solvent. Selectivities for 2‐octanone were observed in the range of 90 % to 99.9 %. Small amounts of C16 compounds were also formed due to aldol condensation/dehydration reactions. The catalysts exhibited higher conversion in the dehydrogenation of secondary alcohols (65‐69 %), in comparison to primary alcohols (2–10 %). The dehydrogenation of 1,2‐octanediol led to 1‐hydroxy‐2‐octanone, with a selectivity of 90 % and 69 % for Co/TiO 2 P25 and Co/TiO 2 P90, respectively.