METAL-ORGANIC FRAMEWORKS APPENDED WITH CYCLIC DIAMINES FOR CARBON DIOXIDE CAPTURE

摘要

Achieving the selective and reversible adsorption of CO2 from humid, low partial pressures streams such as the flue gas resulting from the combustion of natural gas in combined cycle power plants (4% CO2) is challenging due to the need for high thermal, oxidative, and hydrolytic stability as well as moderate regeneration conditions to reduce the energy of adsorption/desorption cycling. Appending cyclic primary, secondary diamines, exemplified by 2-(aminomethyl)piperidine (2-ampd), to the metalorganic frameworks Mg2(dobpdc) (dobpdc4 = 4,4-dioxidobiphenyl-3,3-dicarboxylate), Mg2(dotpdc) (dotpdc4 = 4,4''-dioxido-[1,1':4',1''-terphenyl]-3,3''-dicarboxylate) or Mg2(pc-dobpdc) (pc-dobpdc4 = dioxidobiphenyl-4,4'-dicarboxylate) produces adsorbents of the classes EMM-44, EMM-45, and EMM-46, respectively, that display step-shaped adsorption of CO2 at the partial pressures required for 90% capture from natural gas flue gas at temperatures up to or exceeding 60 °C. Using a cyclic diamine in place of a diamine functionalized with bulky alkyl groups enables fast adsorption/desorption kinetics with sharp CO2 adsorption and desorption steps.