Adsorbent materials and methods of adsorbing carbon dioxide

A pressure temperature swing adsorption process for separating a CO2 from a feed gas mixture, wherein the process comprises:

• a) subjecting the feed gas mixture comprising CO2 to an adsorption step by introducing the feed gas mixture into a feed input end of an adsorbent bed, wherein the adsorbent bed comprises:
• a feed input end and a product output end;
• and
• an adsorbent material selective for adsorbing CO2, wherein the adsorbent material comprises one or more of the following:
• (i) a zeolite having a Si/Al ratio above about 100 and a framework structure selected from the group consisting of AFT, AFX, CAS, DAC, HEU, IMF, ITH, KFI, LAU, MFS, MTT, PAU, RRO, SFF, STF, SXR, TER, TON, TUN, and a combination thereof;
• or
• (ii) a zeolite with a framework structure selected from the group consisting of AFT, AFX, CHA, EMT, EUO, FAU, IRR, IRY, ITT, KFI, LTA, MRE, MWW, NES, PAU, RHO, RWY, SFF, STI, TSC, UFI, VFI, and a combination thereof, having:
• a. a Si/Al ratio of about 3 to about 100;
• and
• b. a potassium cation concentration of about 1% to about 100%;
• wherein the adsorbent bed is operated at a first pressure and at a first temperature, and wherein at least a portion of the CO2 in the feed gas mixture is adsorbed by the adsorbent bed and wherein a gaseous product depleted in CO2 exits the product output end of the adsorbent bed;
• b) stopping the introduction of the feed gas mixture to the adsorbent bed before breakthrough of CO2 from the product output end of the adsorbent bed;
• c) heating the adsorbent bed to a second temperature higher than the first temperature, resulting in desorption of at least a portion of CO2 from the adsorbent bed and recovering at least a first portion of CO2;
• and
• d) reducing the pressure of the adsorbent bed to a second pressure lower than the first pressure and recovering a second portion of CO2, and
• wherein the first temperature is from about −20° C. to about 80° C. and the first pressure is such that the partial pressure of CO2 is from about 3 bar to about 25 bar.