CO2 trapping method combining dimethyl carbonate absorption and membrane desorption

The invention discloses a CO2 trapping method combining dimethyl carbonate absorption and membrane desorption, belonging to the technical field of chemical engineering. The method comprises the following steps of: decarbonizing feed gas containing CO2 by dimethyl carbonate absorption; then carrying out two-stage throttling expansion and membrane desorption regeneration on CO2-absorbed absorbent rich liquor, and discharging CO2 gas generated by the throttling expansion and the membrane desorption out of the battery limit. Compared with a decarbonizing process of the inventor, which adopts the dimethyl carbonate as the absorbent, the new process of the dimethyl carbonate decarburization and the membrane desorption can reduce the comprehensive energy consumption by 5-20 percent. Compared with the propylene carbonate method maturely applied in industry at present, the energy consumption can be reduced by 30-40 percent; compared with the polyethylene glycol dimethyl ether method, the price of a solvent is lower, and polymerization losses are reduced by 40-60 percent; and compared with the low-temperature methane swabbing process, the operating temperature is milder, and the equipment investment is reduced by 30-40 percent. The CO2 removing efficiency can reach 95 percent or above.