Primary Studies On Mixed Conducting Membranes For Hydrogen Separation And Preparation Technology Of Relevant Materials

Mixed-conducting membranes for hydrogen separation have protonic and electronic conductivities under hydrogen-containing atmosphere at elevated temperatures, and thus have the advantages of infinite selectivity to hydrogen. For this reason, they have potential applications in hydrogen production and alkaline conversion. In this thesis, we started from material preparation methods. An improved cellulose adsorption method for preparing perovskite-type oxides had been studied in detail. Influences on calcined temperature by adding CV into perovskite oxides were also studied. Experimental results showed that the adding of appropriate amount of C1 during preparing the precursor by EDTA-citric complexing method could make the densification of BCY 10 membrane more favorable. Hydrogen permeation on classical HTPC material BaCe0?0Y0?0038 was done, and the stabilities of BaCe090Y01003.8 under hydrogen-containing atmosphere and asymmetric hydrogen-permeation atmosphere, respectively, were also studied. No considerable hydrogen could be detected at the sweep side, and it is contradicted with electrochemical characterization results. The probable rate-determining step of hydrogen permeation process is the surface kinetics (that is surface catalysis) or hydrogen splitting and reforming. By EDX analysis on membrane after hydrogen permeation experiments, we found that perovskite-type structure of BaCe090Y010038 couldn抰 be kept uniform under the asymmetric hydrogen-permeation atmosphere. Hydrogen permeation properties of novel mixed-conducting materials BaCeo90- Mn0.1 003-8 were studied in detail. Electrochemical characterization and hydrogen permeation experiments show that BaCe0?0Mn010O3.~ is a proton and electron mixed F conductor at elevated temperatures, and the decomposition and recomposition of hydrogen on the surface of BaCe0?0Mn0?oO~ membrane is the rate-determining-step of hydrogen permeation process. In order to improve the electronic conductivity and the activation of hydrogen Dissertation of Guangtao LI I Abstract on membrane surface, BaCe090Y01003..5/Metal composite materials were studied. Firstly, the calcined and hydrogen permeation ability of BaCeo.90Y0?ioO3-8/Ag cermet material were studied. Later, preparation properties of Ni-Ag-BaCeo.90Y0. 10034 composite materials were further studied. Because of the heterogeneous limitation of conventional solid-state method, a completely new wet chemical synthesis method was invented. This method can effectively realize the homogeneous distribution between perovskite-type oxide and metal phase by H2-TPR, H2-TG and EDX characterizations. In the last chapter, conclusions and further suggestions on preparation of perovskite oxides and development of mixed-conducting membrane for hydrogen separation were put out.