研究実績の概要 |
Herein, we used a new family of 2D material (Ti3C2Tx MXene) for gas membrane application to take advantage of its sub-nanometer d-spacing and the functional groups on the surface. The main challenge to obtain a high separation performance 2D membranes is non-selective defects that form between randomly adjacent stacked nanosheets. Vacuum filtration on AAO substrate was chosen as the best method to improve the interlocking MXene laminates and avoid undesirable defects. The membrane thickness was adjusted between 20 nm to 100 nm with an exact volume of MXene suspension. Gas permeation of MXene membranes was conducted by a Wicke Kallenbach permeation cell. H2 permeance and H2/CO2 selectivity of AAO support were 15000 GPU and ~5, respectively, similar to the Knudsen selectivity of H2/CO2 (4.7). H2 permeance of the membranes with a thickness of~40 nm was about 7800 GPU, while other gases with larger molecular size showed much lower permeances. Accordingly, the H2/CO2 ideal selectivity reached 115, far exceeded the H2/CO2 Knudsen selectivity and the most current membranes. Although the smaller molecular size, the CO2 permeance was about four times lower than N2 and O2. The low CO2 permeance and O2/N2 selectivity can be ascribed to the preferential adsorption of CO2, decreasing the diffusional mobility. The gas permeance of the MXene membranes varied by the thickness between 9000 to 3300 GPUs along with the variation of H2/CO2 selectivity from 50 to 320, which can be attributed to the increased MXene platelets and sieving ability.
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現在までの達成度 (区分) |
現在までの達成度 (区分)
4: 遅れている
理由
The safety issues of using HF for etching the aluminum metal from the MAX phase did not allow us to synthesize our powder at Kyoto University. On the other hand, finding a reliable source to order a fresh and high-quality MXene suitable for gas membrane application was difficult and took few months. Also, we had not been allowed to use lab facilities for a two-month period because of the pandemic.
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