Separation of carbon dioxide from methane 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 CH4 at a first pressure and first temperature;
• b) adsorbing at least a portion of the CO2 in the adsorbent bed;
• c) producing a CO2-lean product stream, wherein the CO2-lean product stream has a lower concentration of CO2 by vol % than the process feedstream;
• and
• d) 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 is linked by nitrogen atoms of an imidazolate anion or its derivative, and wherein the zeolitic imidazolate framework material has an adsorptive loading ratio for CO2 over CH4 of at least 10.