Separation of carbon dioxide from nitrogen utilizing zeolitic imidazolate framework materials

A process for separating CO2 from a process feedstream, comprising:

• a) contacting an adsorbent bed comprised of a zeolitic imidazolate framework material with a process feedstream comprising CO2 and N2 at a first pressure and first temperature;
• b) adsorbing at least a portion of the CO2 in the adsorbent bed, thereby producing a CO2-lean product stream, wherein the CO2lean product stream has a lower concentration of CO2 by vol % than the process feedstream;
• and
• c) producing a CO2 rich product stream at a second pressure and second temperature, wherein the CO2-rich product stream has a higher concentration of CO2 by vol % than the process feedstream;
• wherein the zeolitic imidazolate framework material has a framework structure wherein each vertex of the framework structure is comprised of a single metal ion and each pair of connected adjacent vertices of the framework structure are linked by the nitrogen atoms of an imidazolate anion or its derivative, and
• wherein the zeolitic imidazolate framework material has an adsorptive loading ratio for CO2 over N2 of at least 5;
• and
• wherein the CO2 partial pressure in step a) is greater than the CO2 partial pressure in step d);
• the process feedstream. is comprised of a combustion as stream;
• the CO2-rich product stream has a N2 content of less than about 20 vol % and at least a portion of the CO2-rich product stream is sequestered at a pressure of at least 500 psig.