【作者】 国海光；

【导师】 刘化章；

【作者基本信息】 浙江工业大学 ， 工业催化， 2003， 硕士

【摘要】 甲醇是仅次于合成氨的化工产品和重要的有机化工原料，是C₁化学的基础物质，又是一种清洁燃料。20世纪60年代以来，合成甲醇催化剂在国内外研究领域日益受到重视。虽然从合成气出发合成甲醇已实现工业化，但是所使用的铜基催化剂仍存在抗毒性、热稳定性以及机械强度差等方面的问题。本文针对铜基催化剂耐热性仍较差，从添加除铜锌铝以外的其它组分和改进催化剂的制备两个方面出发，进行了一系列的研究。利用XRD、TPR、BET和TG等方式对催化剂进行表征，并与催化剂活性关联。 1．组成研究了催化剂组成的影响，结果表明随Cu/Zn比的增加，存在两个高活性点，最高点为Cu/Zn=1.0，此时CuO和ZnO分散较好。铝的加入可以提高催化剂的活性，适宜含量是10.0mol％。Mn或Zr助剂单独加入可以提高催化剂活性和耐热性，适宜含量分别是3.0mol％和4.0mol％。Sr、Ce、Mg、Zr、Ag、V、Ti和Ni中只有Sr和Ti对催化剂的活性稍有影响，Zr和Sr对催化剂耐热性有显著影响。 2．沉淀工艺研究了沉淀剂和沉淀方式及前驱物的影响，结果表明不同沉淀剂得到催化剂活性顺序为：Na₂CO₃＞K₂CO₃＞CO（NH₂）₂＞（NH₄）₂CO₃＞NaOH。不同沉淀方式得到催化剂活性顺序为：分步1＞并流＞分步2＞两步＞反加＞正加。Cu与Zn都以醋酸盐为前驱物制备的催化剂中CuO和ZnO特征峰比较弥散，活性较好。 3．并流共沉淀法研究了沉淀温度、焙烧、干燥及老化的影响，结果表明沉淀温度70℃比60℃得到催化剂中CuO和ZnO分散度较高，活性较好。随着焙烧温度的升高，催化剂CuO和ZnO结晶变好，晶粒由小聚大。合适焙烧温度是350℃，时间是9h。采用红外干燥比普通和真空干燥得到的催化剂中CuO和ZnO分散较好，活性较高。老化过程介入超声波有利于各组分的分散和活性提高。 4．pH值摆动法 首次采用此法制备铜基催化剂。发现可显著提高耐热性。不同摆动次数（ST）和pH值范围对催化剂晶形有较大的影响，当ST=3和pH=4～10时，所得催化剂中CuO，特别是ZnO是高度分散的，已接近形成非晶态，还原后铜的分散好，Cu₂O物种较多，活性和耐热性较好。 5．功率超声法研究了沉淀温度和功率大小的影响，结果表明较低沉淀温度浙江工业大学硕士学位论文和大功率超声波有利于催化剂中CuO和Zno组分的分散和活性的提高。在老化过程中继续介入超声波，可进一步提高催化剂活性。 6.制备方法比较并流共沉淀法、pH值摆动法和功率超声法均能得到高活性催化剂，三种方法制备催化剂的初活性与丹麦某工业样相当，pH值摆动法制备催化剂的耐热性比丹麦样好。 7.工艺条件考察了合成气中02和CO:以及反应温度对CO转化率和甲醇得率的影响，结果表明微量O:或CO:可以大大提高CO转化率和甲醇得率，随着0:或CO:含量的增加，催化剂活性先升高后降低，适宜含量分别是0.8一1 .0 mol%和2，O一4.0 mol%。O:含量对液相产物中甲醇选择性影响不大，CO:含量增加使得甲醇选择性增加。随反应温度升高，STY先升高后降低，在270℃最高。 最后，给出了全文工作的总结以及对铜基甲醇合成催化剂研究工作的展望。更多还原

【Abstract】 Methanol is a major chemical product only inferior to ammonia. Being a cleaning fuel, it’s also an important fundamental material in organic and C1 industries. The catalytic system and process for methanol synthesis have been attracting many researchers’ attention since 1960s’. In spite of industrialized process, there still exist many drawbacks of copper-based catalysts, such as poor tolerance to poisoning, low thermal stability and low mechanical strength. A series of Cu/ZnO/Al2O3 catalysts were prepared by adding different kinds of promoter and changing preparation conditions and methods in this article. These catalysts were characterized by the means of XRD, TPR, BET, and TG.It was found that the activity of catalysts reached two tops with increasing Cu/Zn ratio, among which the maximum appeared at Cu/Zn=1.0. XRD patterns had shown CuO and ZnO dispersed very fine in this catalysts.The existence of Aluminum remarkably enhanced the performance especial at its optimum concentration 10.0 mol%. In our experiments, Only Sr and Ti influenced the activity of catalysts within the addition of Mn among Sr Zr Mg Ce Ag V Ti and Ni. While addition of Mn or Zr alone it would increase the activity and thermal stability of the catalysts at its optimum concentration 3.0 mol% or 4.0 mol%.We found NaiCOs was the better precipitation agent than K2CO3 CO(NH2)2 (NH4)2CO3 and NaOH. As the precipitation method, co-precipitation and fractional precipitation 1 method were superior to normal, reverse and two-stage precipitation. Compared with other precursors, acetate was the suitable precursor of catalysts in which CuO and ZnO dispersed highly as XRD patterns shown.We found out precipitation temperature should be 70℃ and the activity of catalysts prepared by co-precipitation improved remarkably when introducing ultrasound during ageing process. Infrared dry method was preferable to traditional and vacuum dry. The suitable calcinations temperature and time was 350℃ and 9 h. XRD patterns showed the higher precipitation temperature and introduction of ultrasound in ageing both benefit to the dispersion of catalysts, so do infrared drying method. With-m-increasing the calcinations temperature, the crystal of CuO and ZnO become larger.We took the first chance using pH swing method and found the optimum swing times were 3 and pH range from 4 to 10. As XRD patterns showed, the crystal phrase changed greatly with different pH and swing times. At the optimum condition the character peaks of CuO and ZnO showed very fine dispersion, the dispersion of Cu after reduction was better, and more Cu2O species.It was found that lower precipitation temperature and higher power is favorable to activity of the catalysts prepared by ultrasound method. The activity of catalysts would improve further if introducing ultrasound in ageing process. This had conformed to XRD patterns results.The high performance of catalysts prepared by the co-precipitation, pH swing method and ultrasound method was similar to that of industrial demark catalysts. The thermal stability of the catalysts prepared by pH swing method is better than that of the demark catalyst.It was found that trace O2 or CO2 in the synthesis gas may accelerate the rate of methanol synthesis. The activity of catalysts increased first then decreased with increasing the O2 or CO2 content, its optimum concentration 0.8-1.0 mol% or 2.0-4.0 mol%. The effect of O2 content on the methanol content in coarse alcohols is light, but increasing the CO2 content resulted in rising of methanol content in coarse alcohols. STY was the highest at 270℃ with increasing reaction temperature.At last the summarization of the whole article and prospect for the research of copper-based catalysts were put forward.更多还原