Issue 39, 2018

Microporous mixed-metal mixed-ligand metal organic framework for selective CO2 capture

Abstract

A microporous mixed-ligand-based metal–organic framework has been synthesized using two different dicarboxylic acid-based ligands (4,4′-biphenyldicarboxylate (BPDC) and imino diacetate (IMDA)) and two different metal ions (Ce3+ and Na+), namely Ce3Na3(BPDC)3(IMDA)3·(DMF)2(H2O)9. The framework built from Ce–Na–carboxylate layers and BPDC pillars consists of 2D slit-shaped pores occupied by extra-framework Na+ ions. The desolvated framework is permanently porous with a BET surface area of ∼771 m2 g−1 and displays moderate CO2 uptake of 2.0 mmol g−1 with a CO2/N2 selectivity (S) of 68 at room temperature and 1 bar. A modest heat of adsorption (23 kJ mol−1) and smooth diffusion kinetics are observed, as reflected in the facile CO2 cycling. Using GCMC methods, the CO2 adsorption isotherm at 298 K was simulated, which matches the experimental isotherm well. The CO2 positions observed from the simulations showed that Na+ ions in the channels serve as favorable adsorption sites for the oxygen atoms in CO2 pointing toward the Na+ ions (O[double bond, length as m-dash]C[double bond, length as m-dash]O⋯Na+ = 3.34–5.87 Å), while some CO2 molecules sit flat on the phenyl rings of the BPDC at a CO2⋯centroid distance of 3.6–3.7 Å.

Graphical abstract: Microporous mixed-metal mixed-ligand metal organic framework for selective CO2 capture

Supplementary files

Article information

Article type
Paper
Submitted
07 Maijs 2018
Accepted
18 Sept. 2018
First published
18 Sept. 2018

CrystEngComm, 2018,20, 6088-6093

Microporous mixed-metal mixed-ligand metal organic framework for selective CO2 capture

R. Maity, D. Chakraborty, S. Nandi, K. Rinku and R. Vaidhyanathan, CrystEngComm, 2018, 20, 6088 DOI: 10.1039/C8CE00752G

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