Cyclical method of producing high-purity nitrogen and optionally a high-purity hydrocarbon from a feedstock containing nitrogen and a hydrocarbon

A cyclical process for the production of a nitrogen fraction with a purity ≧95 mol %, on the one hand, and of a fraction enriched in hydrocarbon, on the other hand, from a feedstock comprising nitrogen and a hydrocarbon, each cycle comprising the following stages:

• i) bringing said feedstock into contact with an adsorbent bed provided with a feed end and with a production end and containing a solid adsorbent chosen from porous hybrid solids, said contacting operation being carried out under a pressure P1≧0.1 MPa and a temperature T1≧0° C.;
• ii) recovering, at the production end of the adsorbent bed, a first nitrogen fraction with a purity ≧95 mol % (2);
• iii) depressurizing the adsorbent bed cocurrentwise down to a pressure P2<P1 where P2≧0.1 MPa, so as to recover, at the production end of the adsorbent bed, a second fraction of nitrogen with a purity ≧95 mol %;
• iv) depressurizing the adsorbent bed countercurrentwise down to a pressure P3<P2 where 0.006 MPa≦P3≦0.05 MPa, so as to desorb the hydrocarbons from the bed and to recover, at the feed end of the adsorbent bed, a first fraction enriched in hydrocarbon
• v) purging the adsorbent bed countercurrentwise using the nitrogen fraction with a purity ≧95 mol % under the pressure P3, so as to recover, at the feed end of the adsorbent bed, a second fraction enriched in hydrocarbon;
• vi) repressurizing the adsorbent bed countercurrentwise using the nitrogen with a purity ≧95 mol % or with the feedstock up to the pressure P1;
• in which said adsorbent has a dynamic capacity with regard to the hydrocarbon of at least 3 mmol/g between 0.25 MPa and 0.05 MPa at 50° C. and a dynamic capacity with regard to the nitrogen of less than or equal to 0.50 mmol/g between 0.25 MPa and 0.05 MPa at 50° C.,
• wherein the hydrocarbon is propylene and the solid adsorbent is MIL 100 (Fe).