Separation of Carbon Isotopes in Methane with Nanoporous
Materials
- Publication date
- Publisher
Abstract
Traditional
methods for carbon isotope separation are mostly based
on macroscopic procedures such as cryogenic distillation and thermal
diffusion of various gaseous compounds through porous membranes. Recent
development in nanoporous materials renders opportunities for more
effective fractionation of carbon isotopes by tailoring the pore size
and the local chemical composition at the atomic scale. Herein we
report a theoretical analysis of metal–organic frameworks (MOFs)
for separation of carbon isotopes in methane over a broad range of
conditions. Using the classical density functional theory in combination
with the excess-entropy scaling method and the transition-state theory,
we predict the adsorption isotherms, gas diffusivities, and isotopic
selectivity corresponding to both adsorption- and membrane-based separation
processes for a number of MOFs with large methane adsorption capacity.
We find that nanoporous materials enable much more efficient separation
of isotopic methanes than conventional methods and allow for operation
at ambient thermodynamic conditions. MOFs promising for adsorption-
and membrane-based separation processes have also been identified
according to their theoretical selectivity for different pairs of
carbon-isotopic methanes