由镁、铝醇盐配合物合成纳米粒子MgAl_2O_4尖晶石

制备尖晶石微粉的方法很多，主要有共沉淀法、焙烧法、溶胶．凝胶法、气相氧化法、热分解法及有机醇盐法。其中金属醇盐水解法效果很好，但由于传统化学方法合成醇盐是以MXn[X为Hal，R，H，NR2，N（SiMe3）2，O，OR]等与醇进行交换反应．有过程复杂且原料不易得到，产率低，纯度达不到要求及后续分离烦琐等缺点，因而应用受到限制。

添加MgAl_2O_4纳米颗粒对MgO-CaO耐火材料致密化及性能的影响

将不同百分含量的MgAl_2O_4纳米颗粒添加到MgO-CaO耐火材料陶瓷复合材料中,在电炉中于1 650℃烧结并保温3 h获得耐火材料试样。用体积密度、表观气孔率、抗水化性、常温耐压强度、晶相形成和显微结构分析等方法对耐火材料试样进行了表征。结果表明,随着MgAl_2O_4纳米颗粒的加入,试样的体积密度增大。但随着MgAl_2O_4纳米颗粒的加入量达到6%,其表观气孔率和耐压强度分别下降和增加,而进一步添加MgAl_2O_4纳米颗粒,由于热膨胀失配,其结果发生了逆转。另外,加入MgAl_2O_4纳米颗粒可以显著提高试样的抗水化性能,这是由于降低了耐火材料中游离CaO的含量,并通过形成致密的微观结构来促进致密化。

A comparative study on H_2S removal using Mg–Al spinel(MgAl_2O_4) and MgO/Al_2O_3 nanocomposites

In this work MgO/Al_2O_3 nanocomposites with weight ratios from 5% to 25% were synthesized by precipitationimpregnation method and their structural properties were characterized. In the next step, the capability of the nanocomposites in H_2S removal compared to Mg–Al spinel(MgAl_2O_4), synthesized through ion-pair complex precursor route and alumina samples, prepared via sol–gel precipitation methods, was investigated. The results indicated that among the studied sorbents Mg–Al spinel presents a distinctly higher H_2S removal. In addition, the MgO/Al_2O_3 nanocomposites compared to the alumina sorbents, exhibited much better performance in H_2S removal. Also CO_2-TPD analysis reveals higher amounts of basic sites for Mg–Al spinel compared to 25 wt% MgO/75 wt% Al_2O_3 nanocomposite.

凝胶模板燃烧法制备铝酸镁纳米晶

以Al(NO3)3·9H2O、Mg(NO3)·26H2O为原料,明胶为模板分散剂,采用凝胶模板燃烧法成功制备MgAl2O4纳米晶,利用TG-DTA、FT-IR、XRD、SEM、TEM和激光粒度分析仪对样品的结构和性能进行了表征。结果表明:该方法能明显降低MgAl2O4的合成温度,最佳制备条件为硝酸盐与明胶质量比为6.29、650℃热处理2h,所得产物粒子形状基本为球形,直径约为20nm,颗粒分散较均匀,晶化良好,属单一尖晶石相。