Double-shelled hollow polymer microspheres as acid and metallic colloid bi-functional catalyst for a deactalization-hydrogenation tandem reaction

Abstract

The double-shelled hollow polymer microspheres with a carboxylic acid in the inner shell and palladium metallic nanocolloids in the outer shell were prepared as a bi-functional catalyst for a tandem reaction including deacetalization on-hydrogenation from benzaldehyde dimethyl acetate to benzyl alcohol. The double-shelled hollow poly(ethyleneglycol dimethacrylate-co-acrylic acid) (PAA) and poly(ethyleneglycol dimethacrylate-co-N-vinyl pyrrolidone) (PNVP) microspheres were synthesized by a two-stage refluxing precipitation copolymerization in presence of 3-(trimethoxysilyl) propyl methacrylate (MPS)-modified silica as seeds to get SiO2/Pt-BA/SiO2/PNVP tetra-layer microspheres with the subsequent hydrolysis of t-butyl ester to acid group and selective removal of the silica inner core and the sandwiched third layer. The palladium nano-colloids in outer-shell were prepared by the in-situ ethanol reduction of Pd(II) after the coordination of palladium acetate with N-pyrrolidone (NVP) groups in presence of SiO2/Pt-BA/SiO2/PNVP tetra-layer microspheres as stabilizers.