NOVELTY - Natural gas containing carbon dioxide is processed in separating apparatus (2) by passing the natural gas to a cathode (9). At the cathode electrochemical reaction of carbon dioxide occurs and carbonate ion is produced. The carbonate ion is moved to anode (10) through electrolyte an substrate (11). The carbonate ion is dissociated into carbon dioxide and water which are ejected out.    USE - For isolating carbon dioxide from natural gas which is used as fuel of fuel cell.    ADVANTAGE - Carbon dioxide is easily isolated from natural gas. The calorific value of natural gas is improved. The method of processing carbon dioxide requires less power, reduced time and effort, and is inexpensive. Natural gas and petroleum are effectively recovered secondarily from the products ejected from the anode.    DETAILED DESCRIPTION - Natural gas containing carbon dioxide is processed in a separating apparatus (2). The apparatus (2) is equipped with an isolating cell (12) consisting of a cathode, molten carbonate electrolyte substrate and an anode. The apparatus (2) further consists of a cathode supply line (15) and cathode ejection line (16) which are connected to the cathode, and anode ejection line (17) connected to the anode. Natural gas containing carbon dioxide is supplied to the cathode through the supply line (15). Carbon dioxide is isolated from natural gas in the cathode, and the natural gas is ejected out through the ejection line (16). An electrochemical reaction of carbon dioxide is performed at the cathode, and carbonate ion is produced. The carbonate ion is moved to the anode through the electrolyte substrate. The carbonate ion is dissociated into carbon dioxide and water in the anode. Carbon dioxide and water are ejected out through the ejection line (17).    DESCRIPTION OF DRAWING(S) - The figure shows the conceptual diagram of carbon dioxide-separating apparatus. (Drawing includes non-English language text).    separating apparatus (2)    cathode (9)    anode (10)    electrolyte substrate (11)    isolating cell (12)    cathode supply line (15)    cathode ejection line (16)    anode ejection line (17)