Method for synthesizing oxalate by CO gas-phase coupling

The invention discloses a method for synthesizing oxalate by CO gas-phase coupling. The regeneration technique in the invention is used for solving the problem that extra NO gas needs to be supplemented due to nitrogen loss caused by nitric acid generated in regeneration reaction. In the invention, NO and nitric acid react to provide NO2 gas to supplement nitrogen loss due to nitric acid generated by the regeneration reaction. The method can recycle the nitric acid generated in the regeneration reaction, so that the utilization ratio of NO is kept at 98% above; and meanwhile, the invention solves the problem of pollution of discharge of nitric-acid-containing wastewater generated by the regeneration reaction.