Preparation And Properties Of Palladium Membranes On Porous Stainless Steel Surface

The excessive development and utilization of fossil energy not only causes people to face energy shortages,but also causes serious environmental pollution.As a renewable energy source,hydrogen energy is one of the most promising energy sources due to its storability,stability,safety and pollution-free.Palladium membranes are widely used for purification and separation of hydrogen due to their unique selective permeability to hydrogen.However,the currently prepared palladium membranes have relatively high cost,poor mechanical strength and poor thermal stability.Therefore,this paper optimizes the process parameters in order to prepare palladium membranes with low cost,good thermal stability,high mechanical strength and excellent hydrogen permeability.In this paper,a porous stainless steel was used as a support,and a TiO2 film barrier layer was introduced between the support and the palladium film,followed by sensitization-activation treatment,and a palladium film was prepared by electroless plating.Scanning electron microscopy(SEM)and atomic force microscopy(AFM)were used to characterize and analyze the surface,cross-section and roughness of the sample,and the chemical composition and content of the film were analyzed and determined by the attached EDS spectrum.Qualitative analysis and quantitative analysis were performed using X-ray photoelectron spectroscopy(XPS)surface elements.The adhesion of the palladium membrane was subsequently tested and analyzed using a micro-scratch instrument.The results show that preparing TiO2 film on porous stainless steel,the surface diameter of the support is reduced and the roughness is significantly reduced.During the sensitization-activation treatment,the agglomeration of palladium particles on the surface of the support is gradually serious as time or temperature rises,the optimized sensitization-activation process parameters were time 2 minutes and temperature 30℃,the palladium particles on the surface of the support after treatment were still elemental palladium.In the electroless plating process,the amount of palladium particles deposited gradually increases with the time required to replace the plating solution,and is most suitable when the replacement time is 1.5 hours.When the stirring speed is 200 r/min,the surface of the palladium membrane is relatively dense,which is caused by a large amount of defects on the surface of the palladium membrane due to slower or faster stirring;When the number of times of adding bismuth is 2 times,the deposition rate of palladium is relatively stable;The deposition rate of palladium increases first and then decreases with the increase of palladium chloride or rhodium,the coating effect is better when the concentration of palladium chloride is 22.31 mol/L and the concentration of rhodium is lmol/L;The deposition rate of palladium gradually increases with the temperature of the plating solution,and the coating quality is better when the temperature is 60℃.On the basis of optimizing the process parameters,the prepared palladium film has good compactness,smooth surface,uniform thickness and good corrosion resistance;When the temperature was 550℃ and 600℃,the palladium membrane was kept in a hydrogen atmosphere for 24 h,and no interdiffusion occurred between the support and the palladium membrane.When the temperature is 500℃ and the pressure difference is 0.1 MPa,the hydrogen permeation amount is 0.0349 mol·m-2·s-1,and the permeability coefficient is 5.9×10-4 mol·m-2·s-1·Pa-1,The activation energy was 21.4 kJ/mol,the selectivity of hydrogen is ∞.