(731b) Large-Scale Computational Study of Zeolite Nanosheets As Pervaporation Membranes for Ethanol Extraction

Large-Scale
Computational Study of
Zeolite
Nanosheets as Pervaporation Membranes for Ethanol Extraction.

Changlong Zou¹
and Li-Chiang Lin¹*

¹William G. Lowrie
Department of Chemical and Biomolecular Engineering, The Ohio State University,
Columbus, OH 43210, USA

Membranes based pervaporation separation is one of the promising energy-efficient and cost-effective approaches for anhydrous
ethanol extraction from the dilute
biomass fermentation broth. By employing molecular dynamics simulations, we have carried out a large-scale computational study to investigate zeolite nanosheets with diverse
structural features as potential candidates for this application. Our results show that zeolite
nanosheets can
offer better separation factors (i.e., highly selective
toward ethanol over water) and orders of magnitudes higher fluxes as compared to other
membranes reported in the literature. The roles of the
bulk part (i.e., non-surface region) and the surface of nanosheets are also explored at an atomic level in
their overall separation performance. We find that the adsorption selectivity of the bulk zeolites and the ethanol
concentration at the nanosheets membrane surfaces can significantly impact the overall
separation factor. Furthermore, our results also suggest that the surface ethanol concentration, particularly the ethanol
concentration at the channel entrance, has a strong correlation with the number of silanol groups around the entrance
and the diameter of the
entrance. Strategically selecting zeolites with a high adsorption selectivity
and surface topologies that maximize the ethanol concentration
at the entrance region of pore/channels are the key to the design of highly selective zeolite
nanosheets membranes. On the
order hand, the overall permeation flux is found to strongly correlate with the
channel density of zeolites along the permeation direction and their pore
limiting diameters. Overall,
this work has demonstrated the enormous potential of zeolite nanosheets as pervaporation membranes. Results obtained
here from a
large-scale computational study also provide atomic-level guidelines into the future design and discovery of the zeolite nanosheet membranes for ethanol/water
pervaporation separation and potentially for other separation applications.