Study On The Support And Coating Of Porous Al₂O₃ Ceramic Inorganic Membrane

In this dissertation, the preparation of Al₂O₃ porous ceramic supportsand Al203 membranes was investigated. First, the major preparation methodof porous ceramic support as well as membrane was summarized accordingto the reported information. The characteristic of various methods wascompared, and the present situation and development of preparationtechnique about Al₂O₃ inorganic ceramic support as well as membrane bothon domestic and international were introduced. On this foundation, Thestudy focused on the control methods and the influencing factors of thesupport pore structure, the membrane pore structure , the membranethickness and the membrane integrity, in order to establish foundationfor the industrialization preparation of high quality porous ceramicsinorganic membranes.The milled а-Al₂O₃ , carbon powder as pore-forming agent were usedto prepared supports by extrusion and solid-state-particles sinteringtechniques. The а-Al₂O₃ powder material initial granularity size and thegrain-size distribution decision the pore structure and the separationperformance of the support, pore-forming agent,sintering additive, andsintering temperature had great effect on the pore distribution andporosity of the support. The result shows that the average diameter ofthe support increased with the particle size increase of raw material.The amount of pore-forming agent was suitable between 7%-10%. Below 5%,the effect of pore-forming did not appear, while above 15%, thebubble-forming effect appeared. Sintering additive helps when the agentamount used is 10wt%, both can get up to the cohesive action, reduces thesintering temperature, and can guarantee the certain pore and porosity.In self-made dryer under room temperature more than 72 hours may guaranteeintegrity and the strength of the support. Establishment suitable heatup system in 1300℃ sintering 2 hours, may make high-quality porousceramic support.The preparation of micro-filtration membrane by solid particlesintering technique combination slip casting method was studied. Thecondition of making membrane liquid stability is investigated, mechanismthat membrane forms had been discussed。а-Al2O3 with means size of 0.8μm was used to prepare micro-filtration membrane. The preparationconditions of stable slurry for coating and the methods of controllingthickness and pore size distribution of membrane were investigated indetail. Controlling the concentration of slurry and the dip-coating timecould control the pore size distribution and thickness of themicro-filtration membrane. Added PVA control viscosity to be helpful forbecome membrane and avoid the crack that prevents membrane. The integritythat cast repeatedly is helpful for to guarantee membrane. The membranemicroscopic structure and the separation performance were characterizedby SEM and gas flow method. The result shows that the membrane to be fine,may meet the need of micro-filtration serve as the micro filter membranedirectly, also can be the transitional layer when may prepare the ultrafilter membrane.So as AlCl3? 6H2O is hydrolysis preparation Bohemite sol. The stablesol may be obtained by select HCl as peptizing agent, the pH is around5, and lays above for 4 hours in 80℃⁸5℃.The content of the sol and thepore of the support has great influence for the integrity of the layer.The dry process of gel needs to be controlled strictly. The agent PVA andDCCA may effectively prevent crack and pinhole and so on membrane defect.The free-defect Al2O3 ultra filter membrane was obtained by the 0.4M soladd 2% PVA and 1% glycerol. The firing temperature influenced the poreof the membrane greatly. The pore size can be adjusted by controlling thesintering temperature.