Chitosan-Pd0 nanoparticles encapsulated in Al, Co-pillared montmorillonite by one-pot process

Abstract

Chitosan-Pd0 (CS-Pd0) nano particles encapsulated in Al, Co-pillared montmorillonite (MMt) nanocomposites were synthesized by a facile one-pot heat treatment method. The MMt was impregnated with Al, Co pillaring reagent, protonated chitosan solution, and Na2PdCl4 solution, followed with a controlled low-temperature (200 °C) heat treatment, resulting in Pd@CS/Al, Co-MMt nanocomposites. Al, Co pillaring effectively expanded the basal spacing of MMt layers from 1.24 nm to 1.82 nm, and generated numerous mesopores in interlayer space, resulting in increase of surface area from 11.8 m2/g to 198.3 m2/g. Due to the well encapsulation of CS chains in the interlayer nano-spaces, the specific surface area of the hybrid nanocomposite underwent a reasonably decrease as the CS content increase. Most of nano-sized Pd species (2–3 nm) chelated with CS chains dispersed well in the interlayer space of the porous Al, Co pillared MMt matrix. The resultant nanocomposite prepared by such facial one-pot process method have similar high comprehensive catalytic performances as applied in coupling reactions to that prepared by regular divided-multistep method. Moreover, it is confirmed that Al pillaring doped with Co and encapsulation of CS chains have synergistic improving effects on the comprehensive catalytic performance of the nanocomposites.