Influence of particle size in Pd-catalysed selective hydrogenation of 1,3-butadiene

Supported Pd nanoparticles are widely used as catalysts for the selective hydrogenation of alkynes and diolefins. They have a high activity, but it remains challenging to limit over–hydrogenation to alkanes. We varied the nanoparticle size of a Pd on carbon catalyst from 2 to 17 nm and studied its effect on the catalytic activity and selectivity in the selective hydrogenation of 1,3-butadiene in the presence of an excess of propylene. The butadiene hydrogenation activity per metal surface atom increased slightly with Pd particle size, from 17 s–1 to 34 s–1 at 25 °C for 2 nm to 17 nm particles. Contrarily, the propylene hydrogenation activity decreased with particle size: from 2.6 s–1 to 0.4 s–1 from 2 to 17 nm particles. Overall, a higher product selectivity was obtained with increasing particle size over the full butadiene conversion range. Altogether, this paper provides useful insight for the rational design of monometallic Pd-catalyst for selective hydrogenation.