【作者】 张旭霞；

【导师】 赵增祺；

【作者基本信息】 内蒙古大学 ， 无机化学， 2008， 硕士

【摘要】 本论文采用共沉淀—喷雾干燥法制备了LaCoO₃及掺杂的La_1-xCe_xCoO₃（x=0．1、0．2、0．3、0．5、0．7、0．9）、LaCo_1-yCr_yO₃（y=0．1、0．2、0．3、0．4、0．5）系列钙钛矿型催化剂粉体材料，采用BET比表面积、XRD、SEM、TPR等方法对催化剂粉体材料进行了形貌和结构的表征分析；并进行了对甲烷催化燃烧的催化活性的研究，研究了这些样品在甲烷燃烧中的催化作用，并初步探讨了掺杂对催化剂热稳定性的影响。干燥方法在催化剂的制备中具有重要的作用，喷雾干燥法是制备细颗粒催化剂的一种常用方法，研究表明，利用该方法可以降低钙钛矿型催化剂的形成温度，减小催化剂的晶体粒度，提高催化剂的比表面积。本文研究了不同的制备条件对比表面积、催化活性的影响，找出了最佳的制备条件。并对共沉淀-喷雾干燥法制备的不同掺杂量的催化剂的结构及性能进行了研究，确定了最佳的掺杂比例。对A、B位不同的掺杂及其对催化活性、热稳定性的影响进行了研究。结果表明：利用喷雾干燥制备的催化剂比用普通烘箱干燥制备的催化剂所需的完全形成钙钛矿的温度降低了100℃；结果同时表明，沉淀剂的浓度比例、老化时间、喷雾干燥的条件、焙烧时间和温度等，都对催化剂的制备具有或大或小的影响。试验表明，掺杂比例为x=0．3、y=0．1时的催化剂的催化活性最佳，不同位的掺杂均改变了催化剂的结构组成及其活性。沉淀剂NaOH：Na₂CO₃的比例为6：1，喷雾干燥，在700℃焙烧5h后，A位掺Ce的催化剂的活性明显增强，起燃温度T₁₀达到391．6℃，虽然掺Cr后的催化剂的起燃温度较高，但温度升至500℃以后，催化剂的转化率迅速提高，且在1200℃焙烧2h后，钙钛矿结构未破坏，并且显示出较好的催化活性，表明LaCoO₃掺Cr后，显示出优越的热稳定性。更多还原

【Abstract】 In this paper, the LaCoO₃ and a series of La_1-xCe_xCoO₃ （x=0.1, 0.2, 0.3, 0.5, 0.7, 0.9）,LaCo_1-yCr_yO₃（y=0.1, 0.2, 0.3, 0.4, 0.5） were prepared by co-precipitation spray method. The appearance and structure of these catalysts were analyzed by BET-specific surface area, XRD, TEM, TPR .etc. The catalytic activity for CH₄ of these catalysts were measured and studied. And the thermal-stability was discussed in brief.Drying method of catalyst is an important factor in catalyst preparation process. Spray drying method is in common use in thin grain catalysts preparation. The method could decrease the form-temperature of catalyst, increase the specific surface area of catalyst, and decrease the granularity of catalyst. In this paper, the influences of different preparation conditions on the specific surface area and catalytic activity of catalyst. The best preparation condition was confirmed. The structure and performances of catalysts with different adulterate rate prepared by co-precipitation spray Method were studied and the best adulterate rate was confirmed. The influence of catalytic activity and thermal-stability of different A B site adulteration was studied. It’s reported that the form-temperature will decrease 100℃by instead common oven drying method with spray drying method. The proportion of precipitator, aging time, conditions of spray-drying and baking time and temperature would influence the preparation of catalyst more or less. The catalyst with adulteration rate of x=0.3 and y=0.1 has best catalytic activity. The structure and catalytic activity of catalyst with different adulteration changed. The catalytic activity of catalyst with A site adulteration of Ce prepared by spray-drying increased, and the start-burning temperature of the catalyst decreased to 391. 6℃; The start-burning temperature of the catalyst with A site adulteration of Cr was higher, however, the translation rate of catalyst rises quickly as the temperature reach to 500℃, and the catalyst display a prefer catalytic activity after baking 2 hours at 1200℃. The result proved that the LaCoO₃ adulterated with Cr has excellent thermal-stability.更多还原