Preparation And Hydrogen Permeability Of Metal Nickel Hollow Fiber Membrane

Hydrogen is an important chemical for the petroleum refining and petrochemical industries.It is also considered as of the most promising and important clean fuels for the next generation to reduce the environmental pollution caused by the excessive emissions of green-house gases.The traditional Pd-based membranes have the unavoidable shortcomings such as high material cost,thermal instability and embrittlement.The metallic nickel hollow fiber membranes has overcome the shortcomings of traditional palladium membranes and demonstrates a potential use in hydrogen production by high temperature hydrocarbon reforming reactions.In this paper,metallic nickel hollow fiber membranes were fabricated by spinning technique.We explored the effect of spinning conditions on the membrane thickness,and further dense metallic nickel hollow fiber membrane is obtained by atmospheric sintering technology.The hollow fiber was characterized by means of SEM,XRD,universal tensile machine and so on.H2 permeation through the Ni hollow fibers was measured under various operating conditions.At first,we fabricated the metal nickel hollow fiber membrane precursors successfully.The experimental results indicated the sintering should be carried out at around 1400? for 3h,under a hydrogen-containing atmosphere so as to reach the required densification of the nickel hollow fiber membranes.Hydrogen permeation through the dense nickel hollow fiber membranes was measured at high temperatures up to 1000?,it is controlled by H-atom diffusion through the membrane bulk,and can be well described by the Sieverts' equation with the activation energy of 51.07 kJmol-1.For the hollow fiber with wall thickness of 256 ?m,the hydrogen permeation flux value reached up to 7.66×10^-3 mol m^-2 s^-1 at 1000? with 100%H₂-permselectivity.The Ni hollow membrane exhibits high stability in CO₂,CO or steam containing atmospheres,and demonstrates a potential use in hydrogen production by high temperature hydrocarbon reforming reactions.The morphology and membrane thickness of the hollow fibers was tuned by varying the spinning parameters like bore liquid flow rate and air gap distance.H2 permeation through the Ni hollow fibers with N2 as the sweep gas was measured under various operating conditions.A rigorous model considering temperature profiles was developed to fit the experimental data.The results show that the hydrogen permeation flux can be well described by using the Sieverts,equation,implying that the membrane bulk diffusion is still the rate-limiting step.The hydrogen separation rate in the Ni hollow fiber module can be improved by 4?8%when switching the co-current flow to the countercurrent flow operation.