Preparation Of Palladium-Copper Composite Membrane And Study On Membrane Property

The world faces many challenges, associated with excessive utilization of fossil fuels and coal, such as poor air quality, greenhouse gas emissions and energy consumption rate. Now there is an increased global willingness to move toward"hydrogen economy"as a potential long term solution to the growing energy challenges and environment problems, it is mainly due to the availability of inexpensive, reliable and clean. The interest in palladium based membrane and palladium alloy composite membrane has recently renewed because this kind of membrane has many excellences, such as very high hydrogen permeation selectivity and permeation rate, good mechanical strength, high thermal stability, good catalysis activity and so on. At fist, people studied on pure palladium membrane and palladium alloy membrane. Now people pay much attention to the palladium alloy composite membrane. Compared with the traditional palladium membrane, Pd-Cu composite membrane is advantageous because of higher permselectivity and permeation rate, better resistance to hydrogen embrittlement, better resistance to poisoning gaseous impurities, and lower cost.We adopt electroless method to get the stable Pd-Cu alloy composite membrane. Among various substrates studied, porous stainless steel is advantageous because of its thermal expansion coefficient being close to that of Pd-based films, ease to process, corrosion resistance, high thermal stability, high mechanical strength, etc., so here we choose the PSS as the substrate. After pre-treatment, a sol-gel method was used to modify the surface of the substrate in order to decrease pore size on the support and make the surface become smoother. We can get a uniform and dense Pd-Cu alloy membrane by introduce this intermedia layer and avoid the intermetallic diffusion. Finally, the composite membrane was placed in program heating furnace in order to form a homogeneous Pd-Cu alloy membrane by thermal diffusion.A scanning electron microscope (SEM) was used to determine the thickness of the Pd-Cu alloy membrane and investigate the membrane surface morphology. The result shows that we can get a dense and uniform membrane by electroless plating method; the composition and phase structure of the composite membranes were determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS); the gas permeation test was carried out in a home-made steady-state permeation set-up; at the last of this dissertation, I analyze some factors which influence the membrane permeation rate, it is concluded that the factors, such as composite of alloy membrane, the morphologies of the membrane surface, the thickness and structure of membrane, temperature and pressure etc., influence the hydrogen permeation rate.