Preparation of microcapsule-supported Pd catalyst using a microfluidic platform

A phosphine-functionalized polystyrene microcapsule with hundreds of microns in size was prepared using a microfluidic platform. The size distribution was narrow and the average size could be adjusted in the range 300-400 μm. The morphology and composition of the microcapsules were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma atomic emission spectroscopy. The results verified the effectiveness of the strategy we proposed for preparing uniform microcapsules with stable Pd immobilization. A Suzuki coupling reaction between aryl halides and phenylboronic acid was used as the model to evaluate their catalytic activity after Pd(PPh3)4 immobilized onto the microcapsule. It was found that the catalytic activity of microcapsule-supported Pd was always higher than that of the corresponding homogeneous catalyst, and was similar with that of the literature reported microcapsule-supported catalyst with about 7-8 μm particle size. Microcapsule-supported Pd with microcapsules of hundreds of microns in size, being easy to recover, showed good reusability and undetected active species loss, its productivity effect and controllability of the microcapsule-supported Pd catalyst were also expected to benefit from continuous preparation using the microfluidic platform. Moreover, they could be potentially exploited in a fixed-bed reactor with high catalyst density and good mechanical stability.

Graphical AbstractPhosphine-functionalized polystyrene microcapsules hundreds of microns in size were continuously prepared using a microfluidic platform. The microcapsules were used to prepare easily recovered, highly efficient, and reusable Suzuki reaction catalysts.Figure optionsDownload as PowerPoint slide