High CO<sub>2</sub> Selectivity of an Amine-Functionalized
Metal Organic Framework in Adsorption-Based and Membrane-Based Gas
Separations
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Abstract
Molecular simulations were used to
assess the potential of a new
amine-functionalized metal organic framework (MOF), Zn-aminotriazolato-oxalate
(Zn-Atz), in adsorption-based and membrane-based gas separations.
Single-component adsorption isotherms for CO<sub>2</sub>, H<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub> were computed and compared with
the available experimental isotherm data. The good agreement between
experiments and simulations motivated us to predict adsorption equilibria
and transport rates of CH<sub>4</sub>/H<sub>2</sub>, CO<sub>2</sub>/H<sub>2</sub>, CO<sub>2</sub>/CH<sub>4</sub>, and CO<sub>2</sub>/N<sub>2</sub> mixtures in Zn-Atz. We then used this molecular-level
information to evaluate adsorption selectivity, permeation selectivity,
working capacity, gas permeability, and sorbent selection parameter
of Zn-Atz for CH<sub>4</sub>/H<sub>2</sub>, CO<sub>2</sub>/H<sub>2</sub>, CO<sub>2</sub>/CH<sub>4</sub>, and CO<sub>2</sub>/N<sub>2</sub> separations. The separation performance of Zn-Atz was compared with
several other nanoporous adsorbents and membranes. Finally, the selectivity
and permeability of mixed matrix membranes where Zn-Atz was used as
filler particles were evaluated by combining molecular simulations
and continuum modeling. Our results showed that this amine-functionalized
MOF is a very good candidate especially for separation of CO<sub>2</sub> from other gases both in adsorption-based and membrane-based separations
due to its high affinity for CO<sub>2</sub>