Fabrication of Pd-ZSM-5 composite membrane on porous alumina substrate and its hydrogen separation performance
In order to obtain a Palladium membrane deposited on the surface of a macroporous alumina support with good hydrogen permeation performance,a secondary growth method was employed to grow a continuous ZSM-5 zeolite modified film on the porous Al2O3 support.A Palladium membrane was deposited on the ZSM-5 zeolite modified support using an electroless plating method,thereby obtaining a Pd-ZSM-5 composite membrane.Detailed analyses of the morphologies of the porous substrate,ZSM-5 modified substrate,and Pd-ZSM-5 composite membrane were carried out using scanning electron microscopy(SEM).Besides,the surface and cross-sectional elemental distributions were analyzed using energy-dispersive X-ray spectroscopy(EDX).Furthermore,to ascertain the hydrogen permeation performance of the composite membrane,the effects of operating temperature,duration,and test pressure on the hydrogen permeability of the Pd-ZSM-5 composite membrane were investigated within a temperature range from 623 K to 773 K.The results indicated that the ZSM-5 zeolite modification layer effectively reduced the roughness and surface pore size of the porous alumina support,facilitating the deposition of Palladium membrane.The prepared Pd-ZSM-5 composite membrane featured an intact and dense surface with a palladium layer of approximately 5 μm and a ZSM-5 zeolite modification layer of about 3 μm.At an operating temperature of 773K and a permeation pressure of 0.1 MPa,the hydrogen permeation flux and H2/N2 permeation selectivity of the Pd-ZSM-5 composite membrane were 0.113 mol/(m·s)and 468,respectively.Furthermore,the hydrogen permeation performance of the membrane remained relatively stable after 300 hours of continuous operation at 773 K.
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