The production of 1,3-butadiene from acetylene includes the dimerization of acetylene and hydrogenation of the dimer. This work investigated the hydrogenation process catalyzed by ionic liquid stabilized Pd nanoparticles. The Pd nanoparticles were dispersed uniformly the in ionic liquid phase by the N-heterocyclic carbene species adsorbed on the surface of the nanoparticles. However, during the reaction, the N-heterocyclic carbene layer was replaced by a hydrophobic byproduct, which caused the Pd nanoparticles to separate from the [BMIm][BF4] phase and the loss of the catalyst from the reaction phase. To solve this, n-heptane was introduced into the reaction system to re-disperse the Pd nanoparticles in n-heptane, and due to this, the Pd nanoparticles maintained a high catalytic activity for a long term. .