The Hydroformylation via Autogenous Cobalt Carbonyl Species Derived from a Heterogeneous Cobalt–Zirconium Precursor

The hydroformylation of 1-olefins derived from Fischer–Tropsch synthesis (FTS) provides an alternative production of oxygen-containing chemicals such as aldehyde or alcohols. Traditionally, homogeneous catalysts have been adopted in the case. Nonetheless, heterogeneous cobalt-based catalysts exhibit facile separation from liquid reactants, offering an opportunity for the continuous improvement of process. Taking homogeneous cobalt carbonyl species (Co₂(CO)₈) catalyst as a reference, the influence of heterogeneous cobalt–zirconium (Co–ZrO₂) catalyst preparation parameters, as well as process conditions on hydroformylation, was studied. Based on the hot filtration and recycle test, it is evident that the hydroformylation catalyzed by Co–ZrO₂ essentially occurred via cobalt carbonyl intermediate species, which was further confirmed by the cobalt loss. Nonetheless, the Co–ZrO₂ catalyst parameters such as the reducibility or crystalline size of Co, as well as reaction conditions like stirring speed rate and hydrogen-to-carbon monoxide (H₂/CO) ratio, influence the formation rate of labile Co₂(CO)₈, thus modifying the hydroformylation. In addition, the Co–ZrO₂ catalyst yielded a significant number of isomerized products, 2-hexene, due to abundance of cobalt ion (Co²⁺) or Co–ZrO₂ interface. The hydroformylation and isomerization mechanism over a heterogeneous Co–ZrO₂ catalyst are schemed to explain those observations.

Graphical Abstract