Semi-hollow LTA zeolite membrane for water permeation in simulated CO2 hydrogenation to methanol

GQ Song and WJ Zhou and C Li and ZG Wang and FY Hu and TC Wang and ZW Li and AJ Tang and MP Harold and SM Liu and S Kawi, JOURNAL OF MEMBRANE SCIENCE, 678, 121666 (2023).

DOI: 10.1016/j.memsci.2023.121666

Linde Type A (LTA) zeolite is an effective inorganic water permeable membrane material due to its inherent Na+-gated water-conducting mechanism. Although dense LTA membranes show excellent water selective perme-ability, the water permeability rate still needs to be improved to drive the CO2 hydrogenation reaction towards methanol production. In this work, we prepared a water-conducting LTA membrane with well- distributed non-penetrative macroholes, resulting in a cheese-like structure that combines the advantages of micro-nanochannels for high water selective permeability and macroholes for quick water diffusion. These semi-hollow (SH)-LTA membranes with different thicknesses and number of macroholes were fabricated via a steam-assisted method by adjusting the amount of water in the precursor solution. The optimized SH-LTA membranes presented an average water permeance of 8.57 x 10-7 mol m-2 s-1 Pa-1 at 200 degrees C along with CH3OH, H2, and CO2 permeances of 3.24 x 10-9, 7.92 x 10-12, and 4.32 x 10-12 mol m-2 s-1 Pa-1, respectively. The membrane stability was verified under continuous mixture gas permeation tests for 10 h between 200 and 300 degrees C. The dissolution-recrystallization route of the SH morphology was confirmed following comprehensive characterizations and complemented by molecular dynamics simulations to elucidate the superior water separation behavior in SH-LTA membrane in comparison with pristine LTA membrane.

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