Preparation Of High-performance Molecular Sieve Membrane And Research For Formation

Molecular sieve membranes, a new type of inorganic membranes featuring withmolecular sieving mechanism, are composed of different types. Carbon molecular sievemembrane （CMSM）, also known as carbon membrane with the relatively large and smallpore network, is mainly prepared by the pyrolysis of polymers precursors. Compared withthe polymeric membrane, CMSM possesses a better thermostability and chemical stability,as well as a higher permeability and selectivity. In the separation technology, CMSM isconsidered to be a better partial substitute for the organic membrane.In the thesis, the aluminum oxide supports`preparation and modification, CMSMprecursors`synthesis, CMSM development and the forming-membrane mechanism havebeen mainly studied. The porous ceramic support is prepared by molding and solid particlesintering, taking alumina as raw material, carbon as pore-forming material, adding a certaincomposition of the binder and additive sintering. After the appropriate sintering, the poresize of support is well distributed, the porosity is49.7%, and the average pore diameter is0.21μm. Modified by sol-gel method, the average pore size of support is0.14μm.Thermosetting phenolic resin of a high char yield has been synthesized under thecondition of the monomer molar ratio of formaldehyde to phenol1.36,0.65%NaOH,85℃constant temperature water-bath water, the reacttion time4h. Compared to the standardsample FTIR, the synthetic product FTIR has the characteristic peaks of thermosettingphenolic resin, and the product is suitable for precursor of CMSM.CMSM is prepared by dip-coating on the modified support. Carboned at600℃, thepermeation rate of CMSM for H₂is67.5×10^-9mol/m²·s·Pa, the ideal separation factor forH₂/N₂and H₂/CO₂are19.6and8.9, respectively, higher than the corresponding value ofKnudsen diffusion. Gases are separated through the carbon membrane based on themolecular sieve mechanism and a potential application of the recovery of hydrogen ishopeful. Gas permeability of CMSM is improved by doping of silicon and zeolite （3）.Furthermore, the thermostability of polymer film during the pyrolysis, chemical structureof carbon films and carbon microcrystalline structure are systematically studied to explorethe forming-membrane memchanism. The research work provides an importantexperimental data and theoretical basis for the development of high-performance CMSM.