Researchers at the Indian Institute of Science Education and Research (IISER) have developed a material that can selectively capture and remove carbon dioxide (CO2) from a gaseous mixture containing hydrogen. The innovation could be used to scrub CO2 from coal gas prior to combustion.

The material, an ultra-microporous nickel-isonicotinate metal organic framework (MOF) developed by Dr. R. Vaidhyanathan and IISER PhD student Shyamapada Nandi, can capture CO2 using a 10-to-1 bar pressure swing. The MOF exhibits a working capacity two orders of magnitude higher than the commercial zeolite-13x, which the researchers say makes it suitable for industrial use.

“MOFs are porous, crystalline structures made by linking metal ions with organic ligands," Vaidhyanathan says. The pores can accommodate gases and small molecules. Moreover, their organic backbone can be designed to bind preferentially to some molecules, making MOFs useful molecular sieves for separation of gaseous mixtures.

The nickel-isonicotinate MOF can withstand the humid conditions of the gasification process. Image credit: DOE/NETL.Made from a single, small ligand, the nickel-isonicotinate MOF is rigid and chemically stable with a long shelf life. It also can withstand the humid conditions of the gasification process. Another advantage of this MOF is the simple one-pot-synthesis process of production and easy scalability, the researchers say.

Although its potential is high, Vaidhyanathan says that challenges in using the MOF for large-scale applications remain. Prolonged life under operating conditions that involve acidic or basic gas streams and high temperatures is a tough expectation to meet, he says.

But it is potentially an important step. “Our work along with other recent findings on rigid ultra-microporous large-surface-area MOFs could provide scalable sorbents with the right stability and working capacity," he says.