Preparation Of SOD Molecular Sieve Membrane And Research On Hydrogen Separation Performance

Membrane separation technology is an increasingly important,convenient and versatile method for separating mixed gases.Compared with other methods,the membrane separation technology has features such as high efficiency,energy saving,and low operating cost in gas separation.Compared with the separation method of the separation unit in the traditional chemical industry,the membrane separation technology has an expandable operation.Since the pore size of the SOD molecular sieve is 0.28 nm,the Si/Al ratio in the composition of the SOD molecular sieve is 1.It has a high framework density and good structural stability.The support SOD membrane has better performance than the non-supported SOD membrane.Thermal stability,molecular sieves generally have acid and alkali resistance.SOD zeolite membrane has a good research prospect in the separation of small gas molecules.Therefore,this dissertation mainly studied the effects of different methods on the morphology and coverage of synthetic SOD zeolite membranes.Then we successfully synthesized a dense SOD zeolite membrane,and studied the separation performance of H2/He and H2/N2.Two methods of in-situ growth,seed immersion and heating pre-crystallization were used to grow SOD zeolite membranes on the Al2O3 support.The membranes synthesized by these three methods were characterized by XRD and SEM.Two in-situ growth methods were used to grow a membrane with a thickness of about 20?m on the support.The SOD seeds were pre-coated with a layer of SOD on the support by dip coating.Then,when the growth membrane is loaded twice,not only enough nucleation centers are formed on the surface of the carrier,but also defects existing on the surface of the carrier are blocked with seed crystals to avoid influence on subsequent growth.A thin layer of SOD molecular sieve membrane was grown on?-Al2O3 substrate by heating pre-crystallization.After pre-crystallization for 1.5 h,a dense membrane was grown on the support.The thickness of the membrane was about 8 ?m,and The thickness of the membrane is uniform.The SOD zeolite membranes prepared by two hydrothermal methods were tested for gas permeation performance.The permeability of H2,He and N2 through SOD zeolite membrane synthesized by two hydrothermal methods at different temperatures with the change of pressure.In general,the permeability of the three gases increases with increasing temperature,but the rate of change of H2 permeability is much greater than that of He and N2.When the osmotic pressure difference is 40 kPa and the temperature is 150 ?,H2/The ideal separation factor of He is 3.178,which exceeds the Knudsen diffusion value of H2/He(1.414),and the ideal separation factor of H2/N2 is 5.460,indicating that the prepared membrane has a certain searation effect for H2/He and H2/N2.