Method for producing liquid methane by comprehensive utilization of exhaust gas carbon dioxide

The invention relates to a method for producing liquid methane by comprehensive utilization of exhaust gas carbon dioxide, comprising the following steps: letting CO2 and H2 react under the catalysisof nickel to generate methane, separating, purifying, and deeply cooling to obtain liquid methane. The method comprises the following specific steps: mixing CO2 and H2, reacting to generate methane and water, cooling to 190-210 DEG C, sending into a cooler, cooling to below 40 DEG C, sending into a water separator, adsorbing through a membrane separator, returning H2 separated by the membrane separator to a heat exchanger, sending methane separated from H2 into a cold box, deeply cooling under the protection of liquid nitrogen at minus 170 DEG C, liquefying into liquid methane, sending the liquid methane into a storage tank to obtain a finished product. By full utilization of exhaust gas, the method is energy-saving and environmentally-friendly, has low production cost and good product quality, is a major technica