Patent ID: 8142746

Claim:
A process for separating CO 2 from a process feedstream, comprising: a) contacting an adsorbent bed comprised of a zeolitic imidazolate framework material with a process feedstream comprising CO 2 and CH 4 at a first pressure and first temperature; b) adsorbing at least a portion of the CO 2 in the adsorbent bed, thereby producing a CO 2 -lean product stream, wherein the CO 2 -lean product stream has a lower concentration of CO 2 by vol % than the process feedstream; and c) producing a CO 2 -rich product stream at a second pressure and second temperature, wherein the CO 2 -rich product stream has a higher concentration of CO 2 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 CO 2 over CH 4 of at least 10; and the adsorptive loading ratio for CO 2 over CH 4 is measured at 301 K and 106.6 kPa.