Preparation And Catalytic Applications Of Ordered Porous Carbon Membrane

Carbon membrane is a kind of porous separation membrane material, which is rich inmicroporous structure, along with temperature resistance, acid and alkali resistance, as wellas ideal separation performance. It has much potential in the application fields of oxygen(nitrogen) enrichment, hydrogen recovery, removal of acid gas and moisture, membranereaction system. However, prior to practically industrial application, it is an urgentproblem to improve the ratio value of performance over cost in order to get marketcompetitiveness.In this thesis, ordered porous carbon membrane (OPCM) was prepared using phenolicresin and polyimide as starting materials. A large variety of advanced techniques, includingthermogravimetry, Firour transformed infrared spectroscopy, scanning electronmicroscopy, transmission electron microscopy, x-ray diffraction, nitrogen adsorption andpermeation, etc., were used to analysis the thermal stability of precursor, evolution offunctional groups, morphology, pore structure, carbon structure and gas separationperformance of resultant OPCM. In the case of phenoic resin as percursor, OPCM wasobtained by organic assembly technique and pyrolysis. The effects of key factors, such ascatalyst type, materals and properties of membrane-forming matrix, pyrolytic temperaturewere investigated on the porous structure and separation performance of OPCM. In thecase of polyimide as precursor, OPCM was prepared by doping with zeolite or maganeticpowder through pyrolysis. The effects of additive type, doping content, pyrolytictemperature, permeating temperature, permeating pressure, were studied with the respectof thermal stability, carbon structure, porous structure and gas separation performance ofOPCM. In addition, catalytic carbon membrane was prepared by introducing catalyst intocarbon membrane to broad the application field. The catalytic carbon membrane was alsoapplied for reaction of the methanol steam reforming.The results have shown that (1) phenolic resin prepared from Na2CO3as catalyst hashigher thermal stability than that from NaOH. The former is prone to retard thermaldecomposition by obtaining higher ordered porous structure. OPCM prepared from Na2CO3as catalyst has the selectivity of89.0(H2/N2) and26.2(O2/N2).(2) Compared tostainless steel and polytetrafluoroethylene, membrane-froming matrix glass posseses largercontact angle and smaller shrinkage rate, from which the phenolic resins-based OPCM hashigher specific surface area, pore volume and satisfactory O2/N2selectivity above10.(3)In comparison with ZSM-5, zeolite5A is better to improve the gas separation performanceof carbon membrane. Carbon membrane obtained by doping0.5%5A and pyrolysistemperature of650oC has the O2/N2selectivity above10.0. With the magnetic powdercontent increasing, the pore volume carbon membrane decreases along with the averagepore size increasing. When carbon membrane was prepared by the magnetic powdercontent of1%, its O2/N2selectivity was2.4, together with the O2permeability reaching380.45Barrer.(4) In the presence of catalytic carbon membrane, the methanol conversion,hydrogen yield, hydrogen selectivity was first increased and then decreased with elevatingthe reaction temperature. The optimum reaction temperature is240oC. Smaller spacevelocity is propitious to improving the methanol conversion and hydrogen yield.