Preparation And Properties Of SAPO-34 Molecular Sieve Membrane Supported On Titanium Alloy Substrate

With the development of social economy,the acceleration of urbanization and the rapid consumption of energy,the problem of environmental pollution is becoming more and more serious,which will not only destroy the ecological environment on which human beings depend,but also endanger human life safety.Catalytic technology has the characteristics of high efficiency,environmental protection and no secondary pollution,and has become one of the most effective methods to control environmental pollution.The most critical part of catalytic technology is the catalyst.Molecular sieve is a kind of crystal material with special pore structure.The preparation of film by molecular sieve has the advantages of small mass transfer resistance,short diffusion path and convenient loading and unloading.The molecular sieve membrane needs to be loaded on a continuous substrate due to its low mechanical strength.Therefore,in addition to the continuity,compactness and uniformity of the membrane itself,the adhesion between the membrane and the substrate is also crucial to the membrane performance.In this paper,SAPO-34 molecular sieve with large specific surface area,strong carbon deposition resistance and excellent hydrothermal aging resistance was used to prepare SAPO-34 molecular sieve membrane with titanium metal as substrate,which has light weight,high strength,good corrosion resistance,good heat resistance,low temperature performance and low elastic modulus.The effects of different synthesis conditions on the synthesis of molecular sieve membrane and the interfacial adhesion between metal substrate and molecular sieve membrane were investigated.The application properties of the prepared membrane materials were preliminarily analyzed.The specific research contents are as follows:（1）Study on the synthesis conditions of SAPO-34 molecular sieve.In this paper,SAPO-34 molecular sieve was synthesized by hydrothermal method.The effects of crystallization time,crystallization temperature and concentration of synthetic solution on the crystal form of molecular sieve were studied.The optimal synthesis conditions were obtained by exploration:crystallization time 24 h,crystallization temperature 180℃,and molar ratio of H₂O to 57.The prepared SAPO-34 molecular sieve had high purity,uniform particle size distribution,and size of 1～2μm.Cu and Ag elements were loaded on the surface of SAPO-34molecular sieve micropores by ion exchange method.XRD,FTIR,SEM and other test results showed that Cu and Ag elements were successfully loaded in SAPO-34 molecular sieve micropores while ensuring the structural integrity of molecular sieve.（2）Preparation of Cu/SAPO-34 molecular sieve membrane on Ti metal mesh.In this paper,Cu/SAPO-34 molecular sieve membrane was prepared by secondary growth method using Ti metal mesh as the substrate.The effects of seed coating times,Cu exchange amount and Si/Al ratio of synthesis solution on molecular sieve membrane were studied.The results show that when the number of drop coating is 30 times,the Cu exchange capacity is 0.03 mol,and the Si/Al ratio of the synthesis solution is 0.3,the prepared molecular sieve membrane has good surface morphology,no pinholes,cracks and other defects,and the Ti metal mesh and Cu/SAPO-34 molecular sieve have excellent bonding strength.（3）Preparation of Ag/SAPO-34 molecular sieve film on Ti metal plate by micro-arc oxidation.Firstly,a ceramic film was in-situ grown on the surface of TC4 Ti plate by micro-arc oxidation technology,and then Ag/SAPO-34 molecular sieve film was prepared on the micro-arc oxidation TC4 Ti plate by secondary growth method.The results show that the growth of molecular sieve film is good,the surface is smooth and continuous,and the oxidation film of Ti plate has excellent bonding strength with Ag/SAPO-34 molecular sieve film.At the same time,the antibacterial performance test results show that the prepared Ag/SAPO-34 molecular sieve membrane exhibits excellent antibacterial effect.