高比表面积介孔氧化铝的制备与表征

发布时间：2017-12-27 10:32

本文关键词：高比表面积介孔氧化铝的制备与表征　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：介孔氧化铝具有较高的比表面积、适宜的孔结构、较高的机械强度和良好的表面酸性等优异性能,在大分子吸附与分离、多相催化、功能材料和陶瓷等领域中得到了广泛的应用,是一种性能优异的催化和吸附材料。目前制备的介孔氧化铝性能较差,尤其在高温下易转变成热力学稳定的刚玉相氧化铝而失去活性,所以研究工艺简单、成本低廉且能获得具有优异性能和高热稳定性介孔氧化铝的工艺方法具有重要的理论与现实意义。本论文首先对以硫酸铝铵为铝源、碳酸氢铵为沉淀剂采用沉淀法制备介孔氧化铝的工艺条件进行了研究,确定的最佳工艺条件为:pH值为9.5、反应温度为60°C、洗涤液为热水(90°C蒸馏水),所得产物经500°C焙烧后得到的介孔氧化铝的比表面积、孔容和孔径分别为571m2/g、0.78cm3/g和6.15nm。其次研究了有机醇PEG和EDTA对介孔氧化铝热稳定性的影响,发现PEG和EDTA均可以提高其热稳定性。其中PEG可有效抑制γ-Al2O3向α-Al2O3的晶型转变,其最佳添加量为1mol%,改性后制备的样品经500°C焙烧后,其比表面积、孔容和孔径分别为589m2/g、0.96cm3/g和6.69nm,经1100°C焙烧后其比表面积、孔容和孔径分别为71m2/g、0.56cm3/g和14.69nm。EDTA的最佳添加量为6mol%,改性后的样品经500°C焙烧后其表面积、孔容和孔径分别为614m2/g、0.97cm3/g和6.69nm。最后通过沉淀-浸渍法制备了Si和La掺杂介孔氧化铝,得到了热稳定性能优异的介孔氧化铝。其中Si的最佳掺杂量为12%,改性后的样品在500°C、700°C、900°C、1000°C、1100°C和1200°C焙烧时相对于未添加样品的比表面积提高率分别为4.9%、12.2%、36.7%、58.47%、69.79%和71.11%,样品经1100°C和1200°C处理后的比表面积、孔容和孔径分别为149m2/g、0.52cm3/g、8.9nm和45m2/g、0.16cm3/g、7.99nm。稀土元素La的最佳掺杂量为9%,掺杂改性后制备的样品经1100°C焙烧后获得的比表面积高达93m2/g,体现了改性后介孔氧化铝的高热稳定性。
[Abstract]:The mechanical strength of mesoporous alumina with high specific surface area, suitable pore structure, high surface acidity and good performance, has been widely used in the field of macromolecular adsorption and separation, catalysis, functional materials and ceramics, catalysis and adsorption material is a kind of excellent. At present, the preparation of mesoporous alumina with poor performance, especially under high temperature into a thermodynamically stable phase of alumina corundum and so on loss of activity, simple process and low cost and can obtain process with excellent properties and thermal stability of mesoporous alumina has important theoretical and practical significance. Firstly, the ammonium aluminum sulfate as aluminum source and ammonium hydrogen carbonate using technology in the preparation of mesoporous alumina by precipitation as precipitating agent was studied, the optimum preparation conditions were: pH value is 9.5, the reaction temperature is 60 DEG C, washing liquid for hot water (90 degrees C distilled water), medium porous alumina products obtained after calcined at 500 ~ C of surface area, pore and Kong Rong were 571m2/g, 0.78cm3/g and 6.15nm. Secondly, the effect of organic alcohol PEG and EDTA on the thermal stability of mesoporous alumina was studied. It was found that both PEG and EDTA could improve the thermal stability of mesoporous alumina. The PEG can effectively inhibit the gamma -Al2O3 transition to crystalline alpha -Al2O3, the optimal dosage was 1mol%, after calcined at 500 ~ C samples prepared by the modified method, the surface area, pore size and Kong Rong were 589m2/g, 0.96cm3/g and 6.69nm, after calcined at 1100 ~ C, the specific surface area of Kong Rong and the pore size were 71m2/g, 0.56cm3/g and 14.69nm. The optimum addition of EDTA was 6mol%. The surface area, Kong Rong and pore size of the modified samples were 614m2/g, 0.97cm3/g and 6.69nm respectively after 500 degree C roasting. At last, Si and La doped mesoporous alumina were prepared by precipitation impregnation method, and the mesoporous alumina with excellent thermal stability was obtained. The optimal doping amount of Si is 12%, the modified samples in 500 ~ C, 700 ~ C, 900 ~ C, 1000 ~ C, 1100 ~ C and 1200 ~ C was compared to samples without surface area increase rate were 4.9%, 12.2%, 36.7%, 58.47%, 69.79% and 71.11%. The sample was 1100 ~ C and 1200 ~ C after the specific surface area, pore and Kong Rong were 149m2/g, 0.52cm3/g, 8.9nm, 0.16cm3/g, 7.99nm and 45m2/g. The optimum doping amount of rare earth element La is 9%. The surface area of the prepared samples is 93m2/g after 1100 degree C calcination, which indicates the high thermal stability of modified mesoporous alumina.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ133.1

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