Metal Organic Frameworks for Carbon Dioxide Adsorption from Flue Gas

Our objective is to incorporate high capacity metal organic framework (MOF) materials into commercially viable carbon dioxide capture applications for coal-fired power plant flue gas. Owing to their very open, accessible and tunable porosity and favorable heats of adsorption, several MOFs show promise in this application. Our approach involves a combination of molecular modeling with synthesis and characterization of novel MOFs. This talk will focus on the synthesis, characterization, and stability and adsorption testing of MOFs for this application. MOFs are a relatively new class of nanoporous materials synthesized in a rational, “building-block” approach by self-assembly of metal or metal oxide vertices interconnected by rigid organic linker molecules. This rational synthesis approach has opened up the possibility of incorporating a wide variety of metal and metal oxide vertices, as well as various functional groups into a MOF structure. Significant progress toward a fundamental understanding of the characteristics required for a MOF suitable for flue gas operation has been achieved. For example, it is now clear that ultra-high surface area MOFs are not suitable for ambient temperature and sub-atmospheric pressure conditions typical for flue gas. A molecular modeling approach on MOF hydrolysis that correlates with experimental data will be provided. The experimental data were generated by subjecting MOF samples to relevant steaming conditions in a combinatorial chemistry heat treatment unit followed by analysis in a high-throughput X-ray diffractometer. Additional results were collected via an in situ high temperature, steam-atmosphere equipped X-ray diffractometer. Many types of MOF materials were prepared and evaluated, ranging from compounds from the open literature to new families of MOF materials prepared via combinatorial and other in-house synthesis strategies. Finally, detailed molecular modeling of adsorption isotherms and MOF hydrolysis show that theory and experiment match closely.