Enhancing the stability of the Rh/ZnO catalyst by the growth of ZIF-8 for the hydroformylation of higher olefins.

Hydroformylation of olefins is one of the most important industrial processes for aldehyde production. Therein, the leaching of active metals for heterogeneous catalysts is an important issue in the hydroformylation reaction, particularly for higher olefins to produce higher alcohols. Here, different Rh/ZnO catalysts with diverse ZnO as a support were investigated and a home-made ZnO support was selected to prepare the Rh/ZnO@ZIF-8 core-shell structure catalyst, which was synthesized by the growth of ZIF-8 with ZnO as the sacrificed template to afford Zn source. Compared with the Rh/ZnO catalyst, the Rh/ZnO@ZIF-8 catalyst demonstrated a better cyclic stability in the hydroformylation of 1-dodecene. Combining the experiment and characterization results, it was concluded that the ZIF-8 shell on the Rh/ZnO catalyst effectively prevented the leaching of metal Rh into the reaction solution. Moreover, the Rh/ZnO@ZIF-8 catalyst exhibited good universality for other higher olefins. This work provides a useful guideline for immobilizing the active species in heterogeneous catalysts for the hydroformylation reaction.