A sustainable process design to produce diethyl oxalate considering NOx elimination.

•A sustainable process design to produce diethyl oxalate through coupling-regeneration circulation is investigated.•A contaminant handling system is applied to diminish nitrogen oxides for environment protection.•A systematical environmental analysis is also carried out to assess this process with the contaminant handling system.•Important trade-offs are theoretically analyzed and investigated by a rigorous steady simulation.•A flowsheet with better economic performance is proposed.