抗还原Ti基混合导体双相膜的制备及“反应/膜分离/反应”耦合条件下的透氧和稳定性研究

The coupling of partial oxidation of methane (POM) and water splitting in a mixed ionic-electronic conducting membrane reactor could produce synthesis gas (a mixture of H2 and CO). However, to date, Co-based or Fe-based perovskite membranes have been verified that their stabilities are poor under the above reaction conditions. To solve this problem, dense dual phase membrane Pr0.1Sr0.9Ti1-xMgxO3-δ(PSTM) and Ce0.9Pr0.1O2-δ（CPO） will be developed in this project, the oxygen permeability and stability of this dual phase membrane will be also investigated systematically under the coupling reaction conditions. By adjusting percentages of CPO (ionic conducting phase) and PSTM (electronic conducting phase), and changing the amount of doped Mg in PSTM, oxygen permeabilities of developed membranes could be figured out. Besides, the influence of porous catalyst layer will be investigated by comprising oxygen permeability of CPO-PSTM membranes with/without catalyst layer. Based on the above research work, the relationship between catalytic reactions on membrane surface and oxygen transport through the bulk membrane will be revealed. It is expected that CPO-PSTM dual phase membrane with high oxygen permeability and excellent stability under reducing atmosphere would be achieved, which will strongly support the development of methane transformation technology in the future.

将甲烷部分氧化反应和水分解反应耦合在混合导体透氧膜的两侧可以获得具有理想H2/CO比例的合成气，目前常用的含有Co或Fe基钙钛矿透氧膜在上述耦合反应条件下的稳定性较差。本项目重点开发由抗还原的Pr0.1Sr0.9Ti1-xMgxO3-δ(PSTM)和Ce0.9Pr0.1O2-δ（CPO）组成的混合导体双相膜，并研究其在“反应/膜分离/反应”耦合条件下的透氧性能和稳定性。通过调节氧离子导电相CPO和电子导电相PSTM的比例，以及改变PSTM中Mg掺杂量，研究双相膜组成对氧渗透性能的影响规律；此外，通过在CPO-PSTM双相膜表面引入多孔催化涂层，比较在耦合反应条件下不同双相膜的透氧量，揭示膜表面催化反应与膜本体氧传输过程之间的相互联系，进而开发出抗化学还原且具有高渗透性能的CPO-PSTM双相催化膜体系，相信此类透氧膜体系的开发将为未来甲烷高效转化技术的发展提供有力支持。

针对目前常用的Co或Fe基钙钛矿透氧膜在“反应/膜分离/反应”耦合反应条件下的稳定性较差的问题，通过元素掺杂调控SrTiO3基钙钛矿的氧离子-电子混合导电性，并与萤石型氧离子导体复合，开发了一系列抗还原的钛基双相膜Ce0.9Pr0.1O2-δ-Pr0.1Sr0.9Ti1-xMgxO3-δ(CPO-PSTM)。在不同反应气氛中考察膜还原稳定性和透氧性能，解析钛基双相膜中电导率和环境氧分压气氛的影响规律和透氧机制，发现钛基双相膜在膜两侧均暴露在还原气氛中时能通过Ti4+/Ti3+、Ce4+/Ce3+的变价获得混合氧离子-电子导电性。钛基双相膜反应器在“H2O/钛基双相膜/H2”、“H2O/钛基双相膜/CH4”、“H2O/钛基双相膜/CH4+CO2”体系中均能稳定运行150 h以上，甲烷转化率和一氧化碳选择性分别超过95 %和90 %，表现出良好的抗还原性能。该类钛基双相膜的开发有望为未来甲烷高效转化和水分解制氢技术的发展提供有力支持。