2017 Fiscal Year Annual Research Report
Project/Area Number |
17J00447
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Research Institution | Hiroshima University |
Principal Investigator |
余 心 広島大学, 工学研究科, 特別研究員(DC2)
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Project Period (FY) |
2017-04-26 – 2019-03-31
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Keywords | Gas permeation / pH-swing / sol-gel / thermal stability |
Outline of Annual Research Achievements |
In my work, BTESE-derived membranes calcinated at 700°C were found to show much higher thermal and oxidation resistance at 550°C in air than 8h. In addition to the pH-swing method, where the thermal stability of BTESE membrane was increased by controlling sol preparation, I proposed firing BTESE-derived membranes at high temperatures. Figure 1 showed the selectivity of H2/CH4 of BTESE-derived membranes fired at 300, 550 and 700°C was 15-120, 20-390 and 500-900, respectively, indicating the selectivity was shifted to a higher level with the increasing preparation temperature. Moreover, after the heat treatment at 550°C in N2 and then in air, membranes prepared at 550 and 700°C remained a high selectivity for H2/CH4 and H2/CF4 about 75-100 and 1600-2000, while the selectivity of H2/CH4 and H2/CF4 for membranes prepared at 300°C were about 30 and 200, respectively. The higher permeation properties were obtained for membrane prepared at 550 and 700°C, suggesting the BTESE membranes prepared at high temperatures increased the thermal stability and oxidizing resistance. BTESE-derived powders were characterized by Electro-Probe Microanalyzer (EPMA), N2 adsorption and TGA. These results showed BTESE powders pretreated in N2 at 550-700°C and then in air at 550°C had larger carbon/silicon ratios and residual weight, suggesting the BTESE powders pretreated at high temperatures in N2 had more stable structures than that of powders pretreated at 300°C.
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Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Conventionally, organosilica bis(triethoxysilyl)ethane (BTESE)-derived membranes are fabricated by BTESE-derived sols and firing at 200-300 °C due to the decomposition reaction of the organic linking groups, ethane groups around 400°C. For further application, such as H2 purification at high temperatures or gas separation under O2 atmosphere, those membrane could not stand. In our study, BTESE-derived membranes calcinated at 550 and 700°C were found to show much higher thermal and oxidation resistance at 550°C even in air for more than 8h. Meanwhile, the 550°C-prepared membranes had high thermal stability and those membranes were used for O2/SO3 separation in membrane reactor at 550°C and showed O2 permeance of 1.5×10-7 mol/(m2 s Pa) and an improved O2/SO3 separation factor of 19 compared with that of a silica membrane.
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Strategy for Future Research Activity |
Due to the incorporation of organic linking units, the pore size of BTESE membranes was successfully controlled to a looser structure than that of tetraethylorthosilicate (TEOS)-derived silica membrane. In additional, the hydrothermal stability was also increased due to the ethane hydrophobicity. Also, BTESE-derived membranes calcinated at 550 and 700°C were found to show much higher thermal and oxidation resistance at 550°C even in air for more than 8h. Such high thermal stabilized BTESE membranes will be applied to membrane reaction for H2SO4 decomposition at 400-500°C. BTESE-derived sols will be prepared by the pH-swing method, membranes will be prepared by coating and firing BTESE sols at 550 and 700°C in N2. The BTESE powders will exposure in H2SO4 high temperature 400 to 500°C and then analyze by FTIR, N2 adsorption and EDS. The membrane performance will be measured by the single gas permeation both before and after H2SO4 vapor under high temperature. The chemical stability of BTESE-derived membrane will be investigated for a long-time course in O2/SO3/steam atmosphere.
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Research Products
(2 results)