Homemade 3-D printed flow reactors for heterogeneous catalysis

The introduction of 3-D printing technologies and continuous flow microreaction system are rapidly gaining attention in the domain of heterogeneous catalysis. It has facilitated a cleaner method for device fabrication and up scalable approach to chemical synthesis. This work reports a rapid development of precise and highly effective microfluidic system consisting of syringe pumps, Pd/Co3O4 loaded catalyst bed and mixer within a few hours with an inexpensive 3-D printing technology using a poly lactic acid (PLA) thermoplastic filament. Quality, performance, and applicability of the printed devices were assessed by characterization and fidelity tests. Firstly, the Pd/Co3O4 catalyst was synthesized in a four-step approach which basically involves the preparation of mesoporous Co3O4 followed by the immobilization of palladium dendrimer encapsulated nanoparticles (Pd-40-DENs). The Pd/Co3O4 catalyst was characterized and showed uniformly distributed palladium nanoparticles on the Co3O4 support. Secondly, the resulting Pd/Co3O4 catalyst was loaded into the 3-D printed catalyst bed and connected to the flow system. The performance of the 3-D printed micro devices was evaluated for the reduction of 4-nitrophenol to 4-aminophenol in continuous flow. The result shows an excellent conversion of the substrate to 4-aminophenol (98%) in 8.00 minutes residence time. The rate of conversion is comparable with previously reported results in batch and continuous flow system. This demonstrates the feasibility of our approach. In addition, continuous usage of the Pd/Co3O4 loaded catalyst bed in the experiment shows excellent catalyst stability and recyclability of more than 5 cycles with an average conversion of more than 90%. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.