Carbon dioxide storage and sustained delivery by Cu2(pzdc)2L [L = dipyridyl-based ligand] pillared-layer porous coordination networks

• 1D coordination polymers are promising materials for CO2 storage and delivery.
• CPL-n MOFs show superior volumetric-based capacities and diffusion kinetics.
• CPL-n based system provided 500% increase in CO2 delivery time at moderate pressures.

CPL-2 (Cu2(pzdc)2(bpy)), CPL-5 ((Cu2(pzdc)2(bpe)), and ZIF-8 (Zn(MeIM)2) [pzdc = 2,3-pyrazinedicarboxylate, bpy = 4,4′bipyridine, bpe = 1,2-di-(4-pyridyl)-ethylene, MeIM = 2-methylimidazolate] were used to study carbon dioxide storage and delivery at low to moderate pressures. Both CPL-2 and CPL-5 showed superior performance over ZIF-8 due to better volumetric-based capacities and superior diffusion kinetics exhibited by the former metal organic frameworks. When compared with an empty vessel, the CPL-n based storage/delivery system provided as much as 500% increase in CO2 constant flow supply time at moderate pressures. A simplified phenomenological yet useful model was developed to predict discharge pressure decay and estimate a lumped parameter related to the molecular diffusivity. Density functional theory was also employed to shed light onto the CO2 hysteretic adsorption process present on the CPL-n materials. Greater CO2 binding interactions were observed near the vicinity of the copper-nodes.

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