Delamination of microporous layered silicate by acid-hydrothermal treatment and its use for reduction of methanol crossover in DMFC

Microporous layered silicate AMH-3 has a 3D ordered porous structure that is therefore very promising as a permselective barrier. However, for use as permselective barrier, the removal of the Na+ and Sr2+ cations located in the intralayer and interlayer spaces and the delamination of an individual layer must be carried out. We successfully obtained delaminated AMH-3 by acid-hydrothermal treatment without the use of swelling agent. The delamination conditions have been optimized to find the best morphology for use as permselective barrier. The pristine AMH-3 and the delaminated AMH-3 were characterized with FE-SEM, N2 adsorption, ICP-AES, 29Si MAS NMR, FT-IR, and WXRD analyses. These results show that the delaminated AMH-3 has a more ordered pore structure than the pristine AMH-3 and that it retains framework crystallinity in the AMH-3 layers. The methanol permeability, proton conductivity and liquid uptake of Nafion membrane coated with a delaminated AMH-3/Nafion nanocomposite layer were examined. This type of membrane was found to exhibit a lower methanol permeability than neat Nafion and to maintain a high proton conductivity. We can thus conclude that delaminated AMH-3 is potentially good permselective barrier for the reduction of methanol crossover in DMFCs.

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► Layered silicate AMH-3 was delaminated without the use of a swelling agent.
► The delaminated AMH-3 retains framework crystallinity in the AMH-3 layers.
► The membrane coated with delaminated AMH-3/Nafion can reduce methanol crossover.