NOVELTY - A transition metal cobalt porous metal-organic framework material comprises metal ion and organic ligand in a solvent complexation by coordination with self-assembled supramolecular network structure compounds. The metal ion is magnesium (II), manganese (II), iron (II), iron (III), nickel (II), copper (II), zinc (II), and/or preferably cobalt (II). The organic ligand includes organic carboxylic acids and their derivatives, and/or amine compounds and their derivatives. The organic ligand is oxygen, sulfur, or nitrogen atom. The solvent includes water, methanol, and/or acetone.    USE - A transition metal cobalt porous metal-organic framework material used for absorbing and separating two or three kinds in a mixed gas of carbon dioxide, methane, and nitrogen gas (claimed), in an oil field gas, coal bed gas, and marsh gas developing and recycling processes.    ADVANTAGE - The transition metal cobalt porous metal-organic framework material has good absorption selectivity to carbon dioxide, methane, and nitrogen gas. It has excellent selectivity to methane, where the methane selectivity balance reaches more than 7.    DETAILED DESCRIPTION - A transition metal cobalt porous metal-organic framework material comprises metal ion and organic ligand in a solvent complexation by coordination with self-assembled supramolecular network structure compounds. The metal ion is magnesium (II), manganese (II), iron (II), iron (III), nickel (II), copper (II), zinc (II), and/or preferably cobalt (II). The organic ligand is organic carboxylic acids and their derivatives, organic sulfonic acid compounds and their derivatives, imidazole compounds and their derivatives, pyridine compounds and their derivatives, and/or amine compounds and their derivatives. The organic ligand is oxygen, sulfur, or nitrogen atom. The solvent is water, methanol, ethanol, ethylene glycol, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, N-methylpyrrolidone, triethylamine, Quadrol (RTM: tetra(2-hydroxypropyl)ethylenediamine), triethylene diamine, cyclohexane, dioxane, benzene, chlorobenzene, ethyl acetate, pyridine, diethyl ether, and/or acetone. An INDEPENDENT CLAIM is included for preparing the transition metal cobalt porous metal-organic framework material, comprising:    (A) dissolving cobalt salt or other metal salt, and organic ligand in solvent, and uniformly stirring at room temperature;    (B) adding the mixed solution in a reaction vessel at 10-200 degrees C for 0.5 hour; and    (C) after precipitation, washing the precipitate, drying, and activating.