Zeolites are commonly used for gas separations due to their abundance, low cost, durability, and effectiveness at performing the separation. However, for some problems, little experimental data, particularly systematic across a range of compositions and topogolies, exists. Beyond a few problems, atomistic pictures of why certain zeolites are effective at separations is lacking. Modeling of gas sorption, particularly by grand canonical monte carlo (GCMC) approaches, offers an enormous potential, but is complicated by the challenge of how to treat extra-framework cations which are normally found on a large number of partially occupied sites. While work exists for predicting cation locations, GCMC is rarely applied to zeolites with mobile cations. We present a modified algorithm for performing GCMC simulations for gas adsorption in realistic zeolites. The algorithm allows for mobility of both the cations and adsorbed gases during both the equilibration and production phase of the GCMC simulation. Simulations are performed on zeolites whose composition closely reflect ones we have successfully studied experimentally in our lab. Single gas adsorption isotherms and isosteric heats of adsorption obtained from experiment and by the new GCMC methods are compared. Selectivities are also estimated using ideal adsorbed solution theory and ratios of Henry's Law constants obtained from single gas adsorption data.

Novel approach for high throughput gas separation screenings of commonly utilized zeolites

247th National Meeting (2014)

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