NOVELTY - Removing carbon dioxide from a gas mixture including carbon dioxide and methane, comprises contacting the gas mixture with a carbon pyrolyzate adsorbent having a carbon dioxide adsorbent capacity at 1 bar pressure of greater than 50 cm3 carbon dioxide per g of adsorbent at 273K, methane adsorption capacity at 1 bar pressure of less than 35 cm3 methane per g of adsorbent at 21 degrees C, and a bulk density of greater than 0.55 g per cubic centimeter of volume.    USE - The method is useful for removing carbon dioxide from gas mixture including carbon dioxide and methane (claimed) e.g. natural gas, biogas, coal bed methane, and syngas.    ADVANTAGE - The method utilizes the adsorbent that has total ash content of less than 1% as measured by American society for testing and materials D2866, bulk density, as measured by American society for testing and materials D2854, of 0.55-1.25 g/cc, carbon dioxide adsorption capacity measured at 1 bar pressure and a temperature of 273K of greater than 50 cm3 carbon dioxide per g of adsorbent, methane adsorption capacity measured at 1 bar pressure and a temperature of 21 degrees C of less than 35 cm3 methane per g of adsorbent, carbon dioxide heats of adsorption and desorption each of which is 5-50 kJ/mole, single pellet radial crush strength for a nominal 3 mm pellet of greater than 7 kP, as measured by American society for testing and materials D4179.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) making carbon pyrolyzate adsorbent that is selective for carbon dioxide in contact with gas mixtures including carbon dioxide and methane, comprising pyrolyzing polymer or copolymer of polyvinylidene fluoride or polyvinylidene chloride to form pyrolyzate, and activating the pyrolyzate under conditions of environment, pressure, temperature, and time to yield the carbon pyrolyzate adsorbent; and    (2) enhancing removal of carbon dioxide from a gas mixture including carbon dioxide and methane in a process for such removal, comprising supplying for use in the process carbon pyrolyzate adsorbent as an adsorbent medium for contacting the gas mixture in the process.