Strasbourg, France – Continuous processes relying on structured catalytic supports are now widespread in industry. Many different open cell foams can used as the support, but these are usually ceramic or metallic in nature, are energy- and material-intensive to make, and can be brittle. Could a PU foam be used instead?
Now, a team of chemists at the University of Strasbourg has developed a polyurethane foam functionalised with palladium that shows promise as a reusable catalyst. Palladium catalysts are widely used in industrial chemical processes, including hydrogenations and coupling reactions.
To test the idea, they first coated a commercially available open cell PU foam, provided by FoamPartner, with a thin layer of polydopamine. This was necessary because of the absence of the microporosity in the foam that is needed to deposit the metal.
The palladium could then be attached strongly to the polydopamine by simply immersing the coated foam in a hydro-alcoholic solution of a palladium(II) salt at room temperature. Scanning electron microscope studies showed that the palladium ions were evenly dispersed.
In two test reactions – the semi-hydrogenation of an alkyne and a Suzuki coupling – the catalyst had high activity, gave good selectivity, and was easy to reuse. It remained stable through 15 cycling tests, being washed in an ultrasonic bath between each run.
The team suggest that the PU foam based catalysts might have applications in multiple different reactions and reactor types because of their simple preparation, good catalytic activity, and ease of reuse.
The work has been published in the journal Green Chemistry.
