Preparation and characterization of composite membrane for high temperature gas211 separation

摘要

A new class of perm-selective inorganic membrane was developed by electroless211u001edeposition of palladium thin-film on a microporous (alpha)-alumina ceramic 211u001esubstrate ((phi)39 mm x 2 mm thickness, nominal pore size 150 nm and open 211u001eporosity (approx) 42 %). The new membrane was characterized by Scanning Electron 211u001eMicrography (SEM), Energy Dispersive X-ray Analysis (EDX) and conducting 211u001epermeability experiments with hydrogen, helium, argon and carbon dioxide at 211u001etemperatures from 473 K to 673 K and feed pressures from 136 kPa to 274 kPa. The 211u001eresults indicate that the membrane has both high permeability and selectivity for 211u001ehydrogen. The hydrogen transport through the Pd-composite membrane closely 211u001efollowed Sievert's law. A theoretical model is presented to describe the 211u001eperformance of a single-stage permeation process. The model uses a unified 211u001emathematical formulation and calculation methods for two flow patterns (cocurrent 211u001eand countercurrent) with two permeable components and a nonpermeable fraction in 211u001ethe feed and a sweep stream in the permeate. The countercurrent flow pattern is 211u001ealways better than the cocurrent flow pattern with respect to stage cut and 211u001emembrane area. The effect of flow configuration decreases with increasing 211u001emembrane selectivity or with decreasing permeate/feed ratio.