An innovative microwave method for large scale preparation of nanocatalysts for industrial applications

Nanostructured metal catalysts are of great interest because of their marked catalytic performances. Consequently, different synthetic methods have been reported in literature but, up to now, all these methods present several drawbacks for their application on industrial scale. Today microwave chemistry is experiencing an exponential growth and it is generally performed using a closed metal cavity, i.e. a microwave oven. However, the current commercial systems present a number of relevant limitations. Multi-disciplinary applications are complicated or even impossible. Therefore industrial scale-up is not straightforward at all and requires very high project and investment costs. Now, we have applied a new microwave method enabling the possibility of working without the constraints. The method is safe and cheap, it enables to obtain the utmost efficiency and control also for industrial applications, without resorting to an ordinary oven. We have successfully adopted our procedure for the synthesis “in situ” of ruthenium, palladium and silver nanocatalysts on different supports that present little average diameters, good morphology and very narrow sizes distribution with an absolute reproducibility. The reduction of the metal was also confirmed by XPS measurements. These nanostructured ruthenium catalysts resulted particularly efficient, in terms of activity and selectivity, in different selective catalytic reactions, such as the hydrogenation of benzene to cyclohexene and of phenol to cyclohexanone. The nanostructured palladium nanocatalysts have been employed in the hydrogenation of cyclohexene to cyclohexane and of benzaldehyde to benzyl alcohol and these results are also promising in an industrial perspective.