钯复合膜表面缺陷修饰材料的研究

The study of defects modification materials on plladium membrane

利用钯膜分离氢是高纯或超纯氢气生产的主要方式，然而，钯膜表面缺陷是影响氢分离纯度的主要因素。本文选择NaA分子筛和γ-Al2O3两种缺陷填充材料对初镀后的钯膜表面缺陷进行修饰，发现两种材料修饰后钯膜透氮量分别下降了57和2倍，NaA分子筛材料修饰后钯膜的透氮量为未修饰钯膜的1/2500。经过补镀和活化后，在相同钯膜厚度（2.5μm）条件下，三种钯膜透氮量分别为1.91×10^-2、6.12×10^-3和4.89×10^-3 m^3/h·m^2·bar[改成标准单位mPa]。不同修饰材料修饰的钯膜的氢氮分离因子顺序为NaA分子筛 〉 γ-Al2O3 〉 无修饰，说明通过修饰钯膜缺陷的方法可提高钯膜的氢分离选择性，且用NaA分子筛材料要优于γ-Al2O3材料，因为NaA分子筛在缺陷中可根据缺陷形状原位生长，更能有效填补缺陷。NaA分子筛材料修饰后的钯膜经过20次300-400℃以及0.1-1.0MPa的温度和压力循环仍保持性能不变，具有较高的稳定性。

Abstract. The high or ultra high pure hydrogen was mainly produced by palladium composite membrane. However, the defects on the surface of palladium composite membrane were responsible for the existence of impurity in hydrogen. The NaA zeolite and γ-Al2O3 were used to modify the defects of palladium membrane. The performances of unmodified ultra-thin palladium membrane and those modified by NaA zeolite and γ-Al2O3 were investigated. The results showed that, the nitrogen permeations decreased 57 and 2 times after modified by NaA zeolite and γ-Al2O3, respectively. After second electroless plating and activation, the nitrogen permeations of palladium membrane with the same thickness modified by NaA zeolite was 1/2500 of the unmodified membrane. The nitrogen permeations of these three palladium membranes were 1.9108×10^-2 , 6.115×10^-3 and 4.892×10^-3m^3/h·m^2·bar. The H2/N2 selectivity of palladium membranes followed the order of NaA zeolite-modified 〉 γ-Al2O3-modified 〉 unmodified. It was indicated that the performance of palladium membrane can be improved by modification. And the performances of palladium membrane modified by NaA zeolite were better than γ-Al2O3. In the stability tests of NaA zeolite modified palladium membrane, the purity of hydrogen remained stable during 20 cycles of temperature and pressure changes in the range of 300-400°C and 0.1-1.0 MPa.