A process for separating carbon dioxide from a fluid containing carbon
dioxide, NO.sub.2, and at least one of oxygen, argon, and nitrogen
comprises the steps of separating at least part of the fluid into a
carbon dioxide enriched stream, a carbon dioxide depleted stream
comprising CO.sub.2 and at least one of oxygen, argon, and nitrogen and a
NO.sub.2 enriched stream and recycling said NO.sub.2 enriched stream
upstream of the separation step.