Method for recovering CO from tail gas generated in synthesis of propionic acid by low-pressure carbonyl of ethanol

The invention discloses a method for recovering CO from tail gas generated in low-pressure carbonyl synthesis of propionic acid from ethanol, and relates to the technical field of chemical synthesis. A detection device is arranged at the downstream of a pressure swing adsorption system for separating non-raw material gas in tail gas, an output branch and a backflow branch are arranged at the downstream of the detection device, the output branch is communicated with a synthesis system, the backflow branch is communicated with the pressure swing adsorption system, and the detection device is used for detecting the content of the non-raw material gas in the tail gas. And when the content of the non-raw material gas exceeds a set value, the tail gas is sent back to the pressure swing adsorption system through the backflow branch. The gas discharged by the pressure swing adsorption system is detected, so that the problem that excessive non-raw material gas is input into the synthesis system as the adsorption capac