Uniform and Stable Pd–Ni Nanocatalysts for Cinnamaldehyde Hydrogenation

Abstract

Selective hydrogenation is a key step in many industrial conversions, such as the production of polymers, drugs, fragrances, and vitamins. Pd catalysts are active but have a low intrinsic selectivity at high conversions. A promising strategy is to combine Pd with a secondary metal within individual metal nanoparticles, tuning the electronic and structural properties that control the catalytic performance. To maximize the efficiency and effectiveness of this strategy, the alloyed particles need to be uniform in composition and particle size. However, this is challenging to realize using industrially relevant preparation methods. We demonstrate that the preparation of supported Pd–Ni nanoparticles by using impregnation with ethylenediamine precursors yields uniform Pd–Ni nanoparticles. The particle size is tuned by varying the metal loading, and the Pd:Ni ratio is varied while controlling an average ∼3.5 nm particle size. The Pd–Ni nanoparticles displayed linear combinations of the individual activities and selectivities of the individual components during cinnamaldehyde hydrogenation. At the same time, catalyst stability was greatly improved since the presence of Ni increased the resistance against Pd leaching. The results discussed are relevant for the preparation of uniform and stable bimetallic nanoparticles, contributing to a better understanding of the composition-performance relationships in bimetallic catalysts.