【作者】 田克胜；

【导师】 王保伟；

【作者基本信息】 天津大学 ， 化学工艺， 2007， 硕士

【摘要】 一氧化碳和亚硝酸乙酯在催化剂的存在下催化偶联合成草酸二乙酯是一环境友好和原子经济反应过程。在以前工作的基础上,本文重点对催化剂进行了研究,考察主催化剂、助催化剂和等离子体处理等制备条件对催化剂性能的影响。在原料配比一氧化碳25%、亚硝酸乙酯15%、氮气60%和停留时间1.8s条件下,在固定床反应器中加入5mL催化剂,考察了各个催化剂在373K、383K、393K温度条件下的催化性能。首先考察活性成分含量对催化剂活性的影响,Pd含量在0.4%-2.0%范围内的一系列催化剂进行考察,对所制备的催化剂的评价结果表明Pd含量为0.8%的催化剂表现出较好的催化活性,催化剂的活性不随Pd含量的增加而线性增长。在助催化剂方面重点对La、Ce、Ti、Cu、Fe、Co、Li几种助剂进行了研究,结果表明镧系元素中的La和Ce的加入明显提高催化剂的性能;在此基础上进一步对La和Ce的加入量进行了研究,结果表明在考察范围内La/Pd(物质的量比)为0.5和Ce/Pd(物质的量比)为1.0时催化剂的性能最好。同时,对助催化剂进行了BET、TEM、XPS和ICP等表征,研究催化剂的组成和催化性能的关系,为进一步改进催化剂提供参考。最后考察了等离子体处理对催化剂性能的影响,考察了含La、Ce、Ti、Fe四种助剂的催化剂在氮气气氛下等离子体处理前后的情况,催化剂的活性与处理前比较有小幅提高;对La-Pd/α-Al2O3催化剂进行氢气气氛下的等离子体处理,草酸二乙酯的空时收率和一氧化碳的转化率比较处理前分别提高了7.8%和8.3%;而对20-40目的Ce-Pd/α-Al2O3在氢气气氛下处理后与处理前比较草酸二乙酯的空时收率和一氧化碳的转化率分别增加了23.8%和25.1%。等离子体处理作为一种新型的化工处理手段在对本实验中所使用的催化剂处理起到明显的效果。结合各种分析结果对活性成分含量、助催化剂和等离子体处理对催化剂性能的影响进行探讨。更多还原

【Abstract】 Synthesis of diethyl oxalate (DEO) via catalytic coupling reaction of CO and ethyl nitrite (EN) is an environment benign and atomic economic process. The effecting factors of catalytic activities, such as Pd loading amount, promoters and the plasma treatment on the catalysts, were investigated in this paper based on former achievements on this subject. The catalysts were evaluated in the fixed bed reactor with 5mL catalyst. The experiments were carried out on catalyst in the same reaction condition of CO 25%, ethyl nitrite 15%, nitrogen 60%, the residence time 1.8s and temperature of 373K~ 393K. A series catalyst was prepared by impregnation method with Pd loadings in the range 0.4-2.0wt%. The results indicated that the catalytic activity of 0.8% Pd/-Al2O3 was the highest among all the catalysts.The influence of promoter was also studied. La, Ce, Ti, Cu, Fe, Co and Li promoters were added in the new catalysts, respectively. The catalysts were prepared by the impregnation method. The results showed that the catalysts doped La or Ce can obviously improve catalytic performance. The molar ratio of La/Pd and Ce/Pd were further investigated in the later experiments. The results indicated that the catalysts reached the best catalytic capability when La/Pd (mol ratio) is 0.5 and Ce/Pd (mol ratio) is 1.0. Meanwhile, the catalysts were characterized by BET, TEM, XPS and ICP, respectively, which can provide the useful information of the catalysts.The catalysts including La, Ce, Ti, and Fe promoters were investigated after they were treated with plasma method under the nitrogen or hydrogen environment. The performance of catalysts treated under the hydrogen environment is better than that under nitrogen environment. Comparing the plasma treated catalyst with untreated, the STY of DEO and the conversion of CO on La-Pd/α-Al2O3 catalyst increased 7.8% and 8.3%; and the STY of DEO and the conversion of CO on Ce-Pd/α-Al2O3 (20-40 mesh) catalyst increased 23.8% and 25.1%. Combining with the catalysts characterization results, the influence of these effecting factors was discussed.更多还原