Microcapsules-supported Pd catalysts with ultralow ionic residues

Catalyst supports play an essential role in improving catalytic activity, preventing site loss, and promoting material diffusion. In this work, polyethyleneimine (PEI) microcapsules were prepared by interfacial crosslink polymerization on micro-droplets. The influence of reaction conditions on the formation of microcapsules was investigated in detail by combining the in-situ observation of optical microscope and kinetic modeling of interfacial polymerization. The obtained microcapsules can strongly absorb Pd2+ with an adsorption capacity of up to 1000 mg/g. The microcapsules-supported Pd (Pd/MCs) presented good catalytic activity for the Suzuki coupling reaction. The apparent activation energy was 28.3 kJ/mol. In addition, the catalyst demonstrated good recycling characteristics. The leakage rate of the Pd ion was less than 0.016%, and the residual amount of Pd in the reaction solution was lower than 0.099 ppm. Moreover, after repeatedly being used 10 times, the conversion efficiency of bromobenzene was maintained above 94%. Preparation of microcapsules-supported Pd catalysts (Pd/MCs) with ultralow residuals by interfacial polymerization based on microfluidic technology. [Display omitted] •Microfluidic-based, preparation of microcapsule by interfacial polymerization.•The in-situ observation and kinetic modeling of interfacial polymerization.•The microcapsule has an excellent Pd2+ adsorption capacity of 1000 mg/g.•The microcapsules-supported Pd have superior stability and ultra-low residuals.