Copper-Cobalt Bimetallic Nanoparticles for the Acceptorless Dehydrogenation of Alcohols: A Combined Experimental and Theoretical Study

Abstract

Bimetallic Cu and Co nanoparticles were prepared using the polyol process. The nature of the polyol was found to be decisive to control the distribution of the two metals within the particles, resulting in either core-shell or quasi-alloyed structures, as shown by chemical analysis at the single particle level. The particles can be prepared over the entire composition range with a very good control of the Cu/Co molar ratio. The introduction of Cu in the synthetic system allows decreasing significantly the mean size of the resulting particles. The two sets of particles were used as unsupported catalysts for the solvent-free acceptorless dehydrogenation of octan-2-ol. Very good ketone yields were measured when using the quasi-alloyed particles while lower activities were obtained with core-shell structures. The Cu₂₅Co₇₅ quasi-alloyed catalyst could be recycled at least ten times without a significant loss in catalytic activity and particle-scale chemical analyses confirmed that the recovered particles are still alloyed with no observed demixing. The catalytic results are discussed in the light of different exposed metal surface areas and possible synergetic effects using theoretical predictions.