Preparation And Characterization Of Porous Stainless Steel Hollow Fiber Membrane

In this paper, spiral porous stainless steel hollow fiber was prepared via a modified phase inversion-sintering technique and the effects of sintering conditions such as sintering atmosphere on the hollow fiber properties have been investigated extensively. The hollow fiber was characterized by means of SEM,XRD,TGA, mercury porosimetry analyzer and so on.Firstly, spiral shaped porous stainless steel (PSS) hollow fiber membranes have been developed via a modified phase inversion-sintering technique using 316 L stainless steel powder as the membrane material, polysulfone as the polymeric binder and N-methylpyrrolidone as the solvent, respectively. The effects of sintering conditions on the hollow fiber properties have been investigated to optimize the preparation. In order to obtain the desired porous structure, high performance and appropriate mechanical strength, the PSS hollow fiber precursors should be calcined in 02-free atmosphere between 1050℃ and 1100℃. Under the optimal sintering conditions, the resultant PSS hollow fiber membranes have a bimodal pore size distribution of 0.1-3 μm diameter, high mechanical strength of 290-600 MPa, and the nitrogen permeances ranged between2.23×10-4 and 2.84×10-5mol m-2 s-1 Pa-1. When two sides are fixed by sealant, such spiral hollow fiber membranes are able to flexibly expand by 20% and shrink by at most 57% of its original length, thus suitable for variable high-temperature operations as they can offset the thermal expansion and contraction caused by the temperature change.The effects of sintering atmosphere, temperature and dwelling time on the microstructure, mechanical strength, and fluid permeation performances of the hollow fibre membranes were extensively investigated. Experimental results indicated that a H2-containing sintering atmosphere was essential to improvement of the microstructure and performance of the PSS hollow fiber membranes, but the positive influence became very marginal as the H2 concentration was higher than 25%. In order to obtain good porous membrane structure as well as sufficient mechanical strength, the sintering temperature in the H2-containing atmosphere should be controlled within a range of 1050-1100℃. The sintering longer than 2 hours yielded quite limited effect on the membrane properties. The resultant PSS hollow fibers satisfy the criteria of porous supports for gas separation membranes in terms of high porosity, high fluid permeance and robustness to withstand stress.