Performance Of LSF Ceramic Hollow Fiber Membrane Reactor For Partial Oxidation Of Methane

Lao7Sr0.3FeO3-δ (LSF) perovskite ceramic powder was fabricated by sol-gel method and was characterized by SEM and XRD techniques. Results show that LSF powder which the particle size is smaller than200nm has pure perovskite structure.The gas-tight LSF ceramic hollow fiber membranes were prepared by the phase inversion-sintering technique. The microstructure of LSF hollow fiber membrane was optimized by controlling the parameters of additive agents, interior coagulant and sintering temperature.The structure of crystal phase, permeability, porosity and bending strength of LSF hollow fiber membrane with different microstructure were characterized. Results indicate that when the additive of P135is added in the dope solution and mixed solution of30wt%EtOH-70wt%NMP as interior coagulant, the LSF hollow fiber membranes calcined at1350℃for4hours possess an asymmetric structure with a porous inner surface and a dense outer layer. Bending strength and porosity could reach131.0MPa and46.8%, respectively. The parameters of additive, interior coagulant and sintering temperature have great effect on permeability, porosity and bending strength of LSF hollow fiber membrane because the pore structure of the hollow fiber membrane changes.Ni/y-Al2O3catalysts were prepared by isovolumetric impregnation method and the catalytic performance of partial oxidation of methane to syngas (POM) was tested with the fixed microtuble-type reactor. The results demonstrate that Ni/y-Al2O3catalysts fabricated in our laboratory possess high catalytic activity and stability. The methane conversion could reach98.9%and the selectivities of H2and CO are greater than94.0%. The catalytic performance of Ni/y-Al2O3catalysts did not degenerate during100hours.The Ni-based catalyst with high catalytic activity was packed in the shell side of the dense LSF hollow fiber membrane to set up membrane reactor (MR) for POM. The hollow fiber membranes before and after POM were characterized by XRD and SEM. The XRD patterns of the membranes before and after POM showed that both of them had perovskite structure. Compare to the surface of the hollow fiber membrane before POM reation, it presented a porous structure after POM reaction. CH4diluted by He and air were fed into the shell and tube sides of the reactor packed with Ni-based catalyst respectively and the oxygen permeability of LSF hollow fiber membrane was studied. The inlet and outlet gas content was measured by gas chromatography. The results of POM reaction revealed that the CH4conversion, the selectivities of CO and H2at900℃could reach99.9%,50.0%and59.3%, respectively. The H2/CO ratio in the product was close to2. Oxygen permeability of LSF hollow fiber membrane during the POM reaction could reach9.6mL·cm-2·min-1and excellent chemical stability were observed in the stability test for100h.