Method for recovering carbon dioxide gas and other gases

A method for separating exhaust gas containing carbon dioxide gas, nitrogen gas and oxygen gas into the carbon dioxide gas and a gas containing the nitrogen gas and the oxygen gas and respectively recovering the carbon dioxide gas and the gas containing the nitrogen gas and the oxygen gas, comprising:

• a gas absorption step of bringing the exhaust gas into contact with an aqueous solution containing alkaline carbonate, so that the carbon dioxide gas in the exhaust gas is allowed to react therewith, thereby obtaining an aqueous solution containing alkaline bicarbonate;
• a gas recovery step of recovering the gas containing the nitrogen gas and the oxygen gas obtained as a result of the gas absorption step;
• a decomposition step of decomposing at least a part of the alkaline bicarbonate obtained in the gas absorption step into the alkaline carbonate and the carbon dioxide gas;
• a circulation step of circulating at least a part of the alkaline carbonate obtained in the decomposition step to the gas absorption step;
• and
• a carbon dioxide gas recovery step of bringing gas containing the carbon dioxide gas obtained as a result of the decomposition step into contact with an aqueous solution, thereby recovering the carbon dioxide gas obtained in the decomposition step;
• and,
• further comprising a first purification step of allowing the gas containing the nitrogen gas and the oxygen gas obtained in the gas recovery step to react with hydrogen gas in the presence of a platinum catalyzer, thereby reducing the oxygen gas contained in the gas, wherein heat generated in the first purification step is used to decomp se at least a part of the alkaline bicarbonate into the alkaline carbonate and the carbon dioxide gas in the decomposition step.