Particle size effects in copper-catalyzed hydrogenation of ethyl acetate

•A method was developed to tune the Cu particle size between 3 and 14 nm on graphitic carbon.•The ethyl acetate hydrogenation activity increased with increasing Cu particle size below 10 nm.•The apparent activation energy was around 94 kJ mol−1 for all Cu particle sizes.•The nature of the active site was size-independent, yet the abundance changed with particle size.•A maximal ethyl acetate hydrogenation activity was achieved with Cu particles of around 6 nm.