New palladium catalysts supported on polyketone: characterization and catalytic activity

Generally, metal nanoparticles catalysts are prepared in the presence of a stabilizing agent in order to prevent their agglomeration. The use of polymeric stabilizers has been widely investigated. These “quasi” homogeneous MNPs offer the advantage of high catalytic activity as the homogeneous ones, but, on the other side, they are not easily separable and recyclable as the heterogeneous ones. In order to overcome this drawback, they are generally supported on a solid inorganic carrier. On the contrary, the applications of polymers as supports have been less investigated. In particular the use of polyketones has been almost neglected. Polyketones are high temperature melting materials, unsoluble in the most common solvents. They might not only act as support, but also as stabilizer through MNP-keto groups interactions without encapsulating them with relatively strong bonds, which could inhibit catalysis as normally occurs with other stabilizer. Hereafter, we report the preparation, characterization and the catalytic activity in the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde of Pd catalysts supported on polyketones synthesized according two different methodologies: i) reduction of the Pd precursor in ethanol under microwave irradiation and ii) reduction of the Pd precursor in ethanol or n-butanol in autoclave under nitrogen overpressure. The bare support and the catalysts have been characterized by 13C CPMAS, DSC, TEM, XPS, ICP and BET. The achieved preliminary results highlight that a polyketone, notwithstanding the low surface area, could be a promising support also for other metals in order to obtain efficient, stable, leaching-free catalysts.