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 50 support was selected to prepare the Rh/ZnO 50 @ZIF-8 core-shell structure catalyst, which was synthesized by the growth of ZIF-8 with ZnO 50 as the sacrificed template to afford Zn source. Compared with the Rh/ZnO 50 catalyst, the Rh/ZnO 50 @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 50 catalyst effectively prevented the leaching of metal Rh into the reaction solution. Moreover, the Rh/ZnO 50 @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. The stability of the Rh/ZnO catalyst in the hydroformylation of 1-dodecene obviously improved, which was attributed to that the ZIF-8 shell on the Rh/ZnO catalyst effectively prevented the leaching of metal Rh.