Assessing zeolite frameworks for noble gas separations through a joint experimental and computational approach

• We conducted Xe and Kr single gas adsorption experiments on several silicieous zeolites.
• Experimental results are used to benchmark an accurate model for noble gas adsorption.
• We screen the Xe/Kr selectivity for all zeolites across a range of pressures.
• The most selective zeolites adsorb through a small pocket or narrow channel mechanism.
• Narrow channel adsorption tends to have better selectivities at higher loadings.

All 229 identified zeotype frameworks are screened in their siliceous form by grand canonical Monte Carlo simulation for their ability to separate a radiochemically relevant Kr/Xe mixture in a pressure swing adsorption process. Prior to screening, our model was benchmarked against experimental single gas adsorption measurements, and it was found that for Kr and Xe a Lennard-Jones 9-6 potential with a softer repulsion than an equivalently parameterized Lennard-Jones 12-6 potential was necessary to accurately model fluid–fluid interactions. Examination of the most promising candidate materials, we concluded that zeolites with small, accessible cages about the size of a Xe atom performed the best initially. Zeolites with narrow pore channels with spots along the pore wall with high local surface area are the best performers across all loadings.

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