“…Mild metal catalysts based on supported copper − ,,,,,,,,− or cobalt are typically reported in the literature, while highly reactive hydrogenation catalysts such as supported Ni, ,, Pd, ,, Pt, ,, and Ru are generally avoided. Several authors demonstrated that the performance of copper catalysts is generally enhanced if they are characterized by both (1) a strong interaction between metallic copper and the support , and (2) the presence of small copper particles (resulting in a high metal dispersion and thus a high metal surface area). ,− ,,,, It was reported that both Cu + and Cu 0 are the active sites in such catalysts, but others refuted this hypothesis and described metallic copper as the only active phase .…”