Study on the Development of Membrane Reactor Utilizing Thermal Diffusion of Oxide Ion

许多研究人员研究了甲烷转化技术，目的是开发一种新的天然气用途。我们发现MgO上氧化铅的晶格氧通过甲烷的氧化偶联将甲烷转化为C2，具有较高的活性和选择性。因此，我们开发了以氧化铅作为氧载体的膜反应器。膜反应器分为三类：催化剂氧化膜在多孔管上（a型）；多孔管上含有催化剂氧化物的液体膜（B型）；具有催化作用的氧化膜（C型）。本研究主要研究A型和C型。对于A型膜来说，多孔管上无泄漏的氧化膜是必不可少的。氧化铅与硅粉的熔点为750 ~ 800个，PbO的熔点为900个，sio_2的熔点为1500个。因此，通过烧制pbo -甲醇浆料，在SiO_2-Al_2O_3管上包覆一层玻璃状无孔膜。表面改性提高了活性。根据添加剂的碱度，在PbO膜中加入碱氧化物可加快反应速度。加入K_2O后，C2的生成速率提高了一倍。通过与甲烷的化学计量反应，对具有高氧迁移率的钙钛矿氧化物作为C型膜管材进行了测试。改性（La-Sr） CoO_3体系的活性高于Pb_<0.02>Mg_<0.98>氧化氧体系，是a型和B型膜反应器的活性位点模型。因此，采用SrCoO_3制成C型膜反应器，与其他类型的膜反应器进行比较。在较宽的反应温度范围内，C型的每表面积比活度比其他化合物高两个数量级。

Methane conversion technologies have been studied by many investigators with the aim of developing a novel use of natural gas. We found that lattice oxygen of lead oxide on MgO converted methane to C2 with high activity and selectivity by oxidative coupling of methane. Therefore, we developed membrane reactors where lead oxide works as the oxygen carrier. The membrane reactors are classified into three categories : Catalyst oxide film on a porous tube ( Type A ) ; Liquid film containing catalyst oxide on porous tube ( Type B ) ; Oxide membrane with catalysis (Type C ) . In this research the type A and C were mainly studied.The leak-free oxide film on porous tube is essential for type A membrane. Lead oxide mixed with silica powder melts at 750-800ﾟC,though the melting point of PbO is 900ﾟC and that of SiO_2is 1500ﾟC.Therefore, a glassy and non-porous membrane was established by firing PbO-methanol slurry coated on SiO_2-Al_2O_3 tube. The activity was promoted by the surface modification. The reaction rate was accelerated by alkali oxide addition in the PbO film according to the basicity of the additive. With K_2O addition the C2 formation rate was doubled.Perovskite oxide with high oxygen-mobility were tested as tube material of type C membrane by stoichiometric reaction between the oxide and methane. Theactivity of modified ( La-Sr ) CoO_3 system was higher than that of Pb_<0.02>Mg_<0.98> O oxide which is a model of active site of the type A and B membrane reactor. Therefore, type C membrane reactor was made using SrCoO_3 for comparison with membrane reactors of other types. The specific activity per surface area of type C was two orders of magnitude higher than that of others in the wide range of reaction temperature.