以淀粉为模板多孔纳米氧化铈的制备及其催化性能研究

为获得多孔纳米CeO₂（氧化铈），以淀粉为生物模板，以Ce（NO₃）₃·6H₂O为铈源，在温和条件下制备出海绵状的多孔纳米CeO₂，同时考察了焙烧温度、碱液、铈源投加量对样品形貌的影响.利用XRD（X射线衍射光谱）、SEM（扫描电镜）、N₂吸附-脱附等表征手段对合成的多孔纳米CeO₂进行物相组成、微观形貌及孔径大小分布的分析.通过湿式催化过氧化试验，探究其对腈纶废水中有机物COD_Cr的催化降解性能.结果表明:①所制备的多孔纳米CeO₂具有多孔结构，孔径分布范围为2~4 nm，孔容为0.225 cm3/g，BET比表面积为256.426 m2/g；②多孔纳米CeO₂的最佳制备条件为1 g淀粉溶解于20 mL水中，加入0.02 mol Ce（NO₃）₃·6H₂O，以5%的氨水调节前驱体混合液pH，以1℃/min升至400℃，焙烧4 h，得到海绵状的多孔纳米CeO₂.③以不同形貌的CeO₂作为湿式催化反应中的催化剂，催化降解腈纶废水中有机物，其中以制备的多孔纳米CeO₂催化性能最佳，COD_Cr去除率可达82.5%.研究显示，焙烧温度、碱液、铈源投加量均可影响样品的形貌，在湿式催化过氧化处理腈纶废水试验中，多孔纳米CeO₂能显著提高废水COD_Cr的去除率. 

Synthesis of Porous Nano Cerium Oxide Using Starch as Template and Their Catalytic Performance Investigation

In order to obtain porous nano CeO₂(cerium oxide), starch and Ce(NO₃)₃·6H₂O were employed as a biotemplate agent and cerium source, respectively. The porous nano CeO₂ was synthesized under mild conditions. Subsequently, the influence of calcination temperature and dosage of alkali and Ce(NO₃)₃·6H₂O on the morphology of the porous nano CeO₂ were investigated. The synthesized CeO₂ was characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, and scanning electron microscopy (SEM). Furthermore, the catalytic performance was studied through the treatment of acrylic fiber wastewater by a catalytic wet peroxide oxidation method. The results indicated that:(1) The nano CeO₂ had a porous structure and with pore size between 2-4 nm, pore volume of 0.225 cm3/g and BET surface area of 256.426 m2/g. (2) The optimum conditions for the preparation of the porous nano CeO₂ were:dissolution of 1 g starch in 20 mL water followed by addition of 0.02 mol Ce(NO₃)₃·6H₂O; pH adjustment of the precursor mixture using an aqueous solution of ammonia (5%); and calcination at 400℃ for 4 h with the heating rate of 1℃/min in air. A nano CeO₂ with cavernous porous structure was obtained. (3) CeO₂ with different morphologies was used as catalyst in wet catalytic reactions for degrading refractory organic matters in acrylic wastewaters. The best catalytic efficiency was obtained with the prepared porous nano CeO₂, and the removal rate of COD_Cr reached 82.5%. In conclusion, the morphology of the CeO₂ was affected by the calcination temperature and dosage of alkali and Ce(NO₃)₃·6H₂O. This porous nano CeO₂ can be used as an effective catalyst for treatment of acrylic wastewaters in wet catalytic peroxidation processes. The removal efficiency of COD_Cr could be significantly improved.