2014 Fiscal Year Annual Research Report
Ultra-thin metal oxide films for gas separation
| Project/Area Number |
26889045
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| Research Institution | Kyushu University |
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Principal Investigator |
SELYANCHYN Roman 九州大学, カーボンニュートラル・エネルギー国際研究所, 学術研究員 (90729790)
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| Project Period (FY) |
2014-08-29 – 2016-03-31
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| Keywords | carbon dioxide / gas separation / laminate membrane / metal oxide / composite materials / nanomembrane / molecular imprinting / carbon-neutral energy |
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| Outline of Annual Research Achievements |
First year research was conducted according to the initial plan of research proposal.
I. Method of the fabrication of the double layer (laminate) membrane was established. Two layers of the laminate membrane were fabricated using the sequential spin-coating on solid glass support in the following order: sacrificial layer > support layer > composite layer, followed by detachment, transfer to porous support and final assembly.
II. Polydimethylsiloxane was chosen as support layer due to its useful properties - high gas permeability and physical stability. Thickness and surface activation of PDMS support layer was optimized. Thinning was achieved by the dissolution of the PDMS precursor in chloroform providing the films up to 100 nm with wide range of gas permeances.
III. Titanium dioxide was used as a matrix metal oxide layer. Thin metal oxide layer was fabricated by sol-gel spin coating method with titanium alkoxide used as precursor.
IV. Group of the compounds, namely, aromatic carboxylic acids were identified as such that possess the suitable CO2 gas affinity (relatively high binding energy of molecule to the gas, predicted by density functional theory). Composition with titania matrix was achieved via the complexation of titanium alkoxide with the carboxylic moiety of the molecule in the precursor solution followed by the quick hydrolysis and condensation into the porous film during the spin-coating process.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Current research progress according to the plan in research proposal:
I. Technology of laminate membrane fabrication was established and optimized using PDMS as a support and titanium dioxide as a metal oxide layers. Membranes have been characterized by UV-Vis spectroscopy and optical microscopy, scanning electron microscopy. Activation of the PDMS surface by oxygen plasma resulted in reduction of gas permeances due to formation of thin silicon oxide barrier on the surface of PDMS. Therefore the effect of plasma was further investigated and optimized in order to modify the surface in a way for reliable adhesion, avoiding the formation of additional gas barrier. Reduction of the plasma treatment time to several seconds was needed. It enabled the suitable adhesion of the composite metal oxide as a second layer of the membrane.
II. Gas permeation tests conducted with fabricated membranes confirmed that composite layer formed on the surface of PDMS can be designed in order to change the gases permeation in a desired direction. Abundance of the CO2 philic groups in the composite layer is expected to enhance the selectivity to CO2. Aromatic carboxylic acids (benzoic, phthalic, mellitic, etc.) were used for composition (molecular imprinting) in titania, in order to add CO2 philicity into the composite coating.
III. Gas adsorption experiments with bulk composites were initiated, additionally to initially planned experiments. The porosity, specific surface area, gas sorption in ambient conditions (~25 deg. C) needed to explain the mechanism of gas transport in composite materials.
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| Strategy for Future Research Activity |
Possibility of the formation of CO2 selective sites in thin metal oxide film was confirmed on the first stage of research with the series of gas separation tests. The mechanism of increased selectivity, is still not completely clear. Therefore, series of experiments and computer simulations are planned.
I. Bulk gas sorption at elevated pressures and temperatures are needed to assess the suitability of the developed materials at close to real conditions used in gas separation needs.
II. Density functional theory calculations aimed to explained the molecular level interaction between the gas molecules and template molecules incorporated within the metal oxide matrix. This is planned to be done in the collaboration with computational chemistry specialists of I2CNER institute, Kyushu University. Compliance of the theoretical predictions with the experimental gas separation/gas sorption is expected to increase the impact of the conducted research and also to develop the model for composite material properties prediction regarding their potential application for carbon neutral energy applications.
III. The ultimate goal of the current research is the development of membranes suitable for CO2 separation from the real flue gas (e.g. gas-fired, ~7-8% CO2, ~14% H2O, ~4% O2, 200-300 ppm CO, 60- 70 ppm NOx, and ~73-74% N2). Such experiment is desired in future, after laboratory level tests are completed and mechanism of gas transport through the membrane is explained.
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Research Products
(1 results)
