Preparation Of Carbon Molecular Sieve Memberane And Application For Hydrogen Separation

Carbon molecular sieve membrane (CMSM) as a new and efficient gas separation membrane has been developed in recent years. Compared with ordinary ceramic membranes, CMSM not only has a high flux but also has good separation selectivity. These outstanding features make it raise in the position of the field of membrane separation. Along with the gradual in-depth study, it has been more extensive used in gas separation. The preparation and surface modification of support is studied, as well as the synthesis of precursor and the gas permeability test, which provides a theoretical basis for separating hydrogen from gas mixture.Under appropriate firing process, it is usedα-Al₂O₃ as the aggregate, toner as the pore-forming agent, TiO₂ as a additive sintering, and add a certain composition of the binder. Then put the raw material under a certain suppress and form a shape of Al₂O₃ micro-filtration support. ZrO₂ is uesd modifying the surface of support. The powder particle size is small enough to mill under 4h so that the composition is well distribute and uniform. Y₂O₃ play a significant role in stabilizing the phase of zirconia in the tetragonal zirconia at 1250℃. Using composite sol on the surface of body modification, we can get the support average pore size is 0.4μm and the porosity is 46%, which is the ideal support material.A gold and transparent polyamic acid which will be used as a precursor has been synthesized, from 4,4'-diamino diphenyl(ODA) and pyromellitic dianhydride(PMDA) by solution polycondensation. The monomer molar ratio is 1.015:1. Under the temperature of 3℃, the systerm has reacted 4h. The chemical structure is analyzed by FTIR and intrinsic viscosity. With the presence of the characteristic peaks, the products is proved to be polyamic acid and the viscosity is suitable for coating.Coating the precursor on the modified support, it find doping of silicon on the former has more obvious effects of modification. The most concentrtive pore diameter of CMSM is about 3.8nm after coating three times. It can be repeated to reduce the pore diameter.Through the test of gas permeability, it can be calculatedαH₂/CO₂ up to 25.6 and the maximum ofαH₂/N₂ is 150.49. The research work provides an important basis data for the research of H₂ gas separation membrane technology.