A 3D porous metal-organic framework and method of making are described. In some embodiments, a 3D porous metal-organic framework may be based on a trinodal (3,3,4) net of zyg topology by the self-assembly of the nonlinear hexacarboxylate (BHB) with the paddle-wheel Cu2(COO)4 cluster. Although its porosity and surface area are moderate, the open copper sites and optimal pore spaces enable the pore spaces to be fully utilized for methane storage, resulting in a high methane storage density and high absolute volumetric methane storage at room temperature and 35 bar. By the immobilization of high density open metal sites and the deliberate control of the pore space for their efficient methane storage, this porous MOF functions as an efficient media for methane and natural gas storage.