jz6b02443_si_004.mpg (3.38 MB)
CO Separation from H2 via Hydrate Formation in Single-Walled Carbon Nanotubes
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posted on 2016-11-15, 00:00 authored by Wenhui Zhao, Joseph S. Francisco, Xiao Cheng ZengHydrogen is an alternative
fuel without generating greenhouse gas
or other harmful emissions. Industrial hydrogen production, however,
always contains a small fraction of carbon monoxide (CO) (∼0.5–2%)
that must be removed for use in fuel cells. Here, we present molecular
dynamics simulation evidence on facile separation of CO from H2 at ambient pressure via the formation of quasi-one-dimensional
(Q1D) clathrate hydrates within single-walled carbon nanotubes (SW-CNTs).
At ambient pressure, Q1D CO (or H2) clathrates in SW-CNTs
are formed spontaneously when the SW-CNTs are immersed in CO (or H2) aqueous solution. More interestingly, for the CO/H2 aqueous solution, highly preferential adsorption of CO over H2 occurs within the octagonal or nonagonal ice nanotubes inside
of SW-CNTs. These results suggest that the formation of Q1D hydrates
within SW-CNTs can be a viable and safe method for the separation
of CO from H2, which can be exploited for hydrogen purification
in fuel cells.