One of the emerging problems plaguing the chemical industry today is the efficient and cost-effective separation of C-2 hydrocarbons. In order to help address this problem, we report a new material, NbU-1, constructed by extremely cheap starting materials. The special structural characteristics of NbU-1 such as the planar, mixed-valence copper clusters and Lewis-basic adsorption channels enforce interactions with acetylene molecules that lead to the highest kinetic separation efficiency for C2H2/C2H4. Via DFT-D calculations, it is indicated that C2H2 molecules are adsorbed onto the two adjacent Cu(I) centers, but not the usual single open metal sites of Cu centers. The reported results not only provide information for a deep investigation into the separation mechanism but also offer an alternative strategy for preparing cost-effective materials that can perform highly efficient separations of light hydrocarbons.