High-efficient dynamic kinetic resolution of amines with a core-shell hollow mesoporous MIL-101@Pd@ZIF-8 nanocatalyst and lipase

A composite hollow mesoporous MIL-101@Pd@ZIF-8-30min (HM-MIL@Pd@ZIF-30min) nanocatalyst with hollow core and stable shell was developed in this study. Hollow mesoporous MIL-101(HM-MIL) was hydrothermally synthesized and employed as the supports of Pd nanoparticles by adopting a facile HM-MIL-template strategy to make ZIF-8 crystals uniformly overgrew on HM-MIL-101@Pd microcrystal cores. The obtained core-shell catalyst possessed hollow mesoporous structure, and the shell layer of ZIF-8 had additional advantages of abundant Lewis basic sites for heterogeneous racemization reaction. Compared with unmodified HM-MIL@Pd and solid MIL-101(Cr)@Pd@ZIF-8 (S-MIL@Pd@ZIF-8), HM-MIL@Pd@ZIF-8-30min had higher racemic chemical activity (conv. 99%) and selectivity (sel. R-amide 94%) in one-pot dynamic kinetic resolution (DKR) reaction system of rac-1-phenethylamine. The catalyst showed excellent stability, and the conversion and selectivity reached 95% and 93% respectively after ten catalytic cycles.