文献类型：学位论文

中文题名：草酸二甲酯加氢制乙二醇CU/SIO2催化剂改性研究

英文题名：Study on Cu//SiO/_2 Catalyst of Dimethyl Oxalate Hydrogenation to Ethylene Glycol Modification

作者：刘会杰[1];

机构：[1]华东理工大学;

导师：李伟;华东理工大学

授予学位：硕士

语种：中文

中文关键词：草酸二甲酷;加氢;乙二醇;沉淀剂;助剂

外文关键词：Dimethyl Oxalate;Hydrogenation;Ethylene Glycol;Precipitator;Promoter

摘要：从合成气出发,由CO气相催化偶联合成草酸酯,草酸酯再催化加氢制备乙二醇的煤化工工艺路线,因其工艺流程简单、能耗小、乙二醇的选择性相对较高,是最有工业应用前景的乙二醇合成路线。但草酸二甲酯加氢合成乙二醇Cu//SiO2催化剂存在对温度敏感,在高温下易发生副反应,稳定性差的缺陷,限制了其工业化,本文针对Cu//SiO2催化剂存在的上述问题,通过改变沉淀剂和添加助剂对其进行改性研究。利用XRD、BET、H2-TPR、CO2//NH3-TPD等表征技术,考察了对催化剂体相、还原性、表面酸碱性的影响及其与催化性能之间的联系。论文的主要内容和结果如下： 首先,采用不同的沉淀剂和沉淀方式制备30wt/%Cu//SiO2催化剂。在一定的条件下,考察了沉淀剂、沉淀方式和钾钠离子对催化剂活性和乙二醇选择性的影响,结果表明,采用尿素沉淀剂制备的催化剂有较好催化性能,具有高的低温催化活性和选择性,因此采用尿素作为沉淀剂制备的Cu//SiO2催化剂有继续探索和研发的价值；对于不同沉淀剂,沉淀方式对于Cu//SiO2催化剂性能的影响不同,应根据沉积剂选择沉淀方式；与钾离子相比,钠离子更容易洗涤,但少量钠离子的存在就会抑制MG进一步加氢生成目标产物EG,从而降低了EG的选择性。 其次,加入Al、Zn、Mg和Ca四种助剂,催化剂考评结果表明：四种助剂均在不同程度上对Cu//SiO2催化剂活性有抑制作用,但适量Mg助剂的加入在稍降低催化剂活性的条件下,使MG选择性在较大温度范围内保持在较高的值,借此可以开发出一种高活性的草酸二甲酯加氢合成乙醇酸甲酯催化剂； 最后,对Cu//SiO2催化剂进行CO2-TPD和NH3-TPD表征发现其酸位浓度//碱位浓度=3.09,催化剂显酸性,而四种助剂的加入在不同程度上增加了催化剂的碱性,其顺序为Mg>Zn>Al>Ca,同时研究还发现四种助剂的加入在不同程度上降低了催化剂的还原性,使催化剂难于还原。
The synthesis process of ethylene glycol/(EG/) from synthesis gas is the most promising synthetic route for industrial application, due to its simple process, low energy consumption and relatively high selectivity of EG, which includes oxidative coupling reaction of carbon monoxide to dialkyl oxalate, and the catalytic hydrogenation of dialkyl oxalate to ethylene glycol. However, the Cu//SiO2 catalyst of ethylene glycol from dimethyl oxalate hydrogenation is sensitive to reaction temperature which leads to side reactions in high reaction temperature, and the catalyst has poor stability. In this paper, the performance of Cu//SiO2 catalyst was modified by different precipitators and promoters, bulk structure、reducibility、acidity and basicity of catalysts's surface and their effects on the catalytic performance were studied by XRD、BET、H2-TPR、CO2//NH3-TPD. The main contents of this paper are as follows: Firstly, Cu//SiO2 catalysts with 30wt/% of Cu were prepared with different precipitators and methods. Under certain conditions, the effects of precipitators、precipitation methods、potassium and sodium ions were investigated, the results showed that the Cu//SiO2 catalysts prepared by homogeneous deposition-precipitation methods with urea as precipitator had better catalytic performance with high catalytic activity and selectivity of EG, therefore, Cu//SiO2 catalyst with urea as precipitator had the value of research and development; For different precipitators, the precipitation methods had different effects on Cu//SiO2 catalysts'performance, precipitation method should be chosen, according to different precipitators; Compared with potassium ion, sodium ion was more easily to be washed, but a small amount of sodium ion would inhibit the further hydrogenation of MG and reduce the selectivity of EG. Secondly, the results of catalysts evaluation showed that adding Al、Zn、Mg and Ca promoters restained the activity of Cu//SiO2 in different degrees. Though adding 3wt/% of Mg promoter decreased the activity of Cu//SiO2 catalyst slighly, it can keep the selectivity of MG in high value in larger temperature range, therefor a high activity catalyst of dimethyl oxalate hydrogenation to methyl glycollate can be developed. Lastly, it's found that the ratio of acid sites concentration and basic sites concentration of Cu//SiO2 catalyst was 3.09 by CO2-TPD and NH3-TPD, which showed the Cu//SiO2 catalyst was acidic, however, adding four promoters decreased the acidity, the order was Mg>Zn>Al>Ca. Besides, it's found that four promoters reduced the reducibility, made the catalysts difficult to be reduced.