Pr-Zr氧化物固溶体制备、特性及催化性能研究

发布时间：2018-07-05 06:57

本文选题：Pr-Zr氧化物固溶体 + 甲烷选择生氧化　；参考：《昆明理工大学》2015年博士论文

【摘要】：我国是个稀土大国,稀土的储量和产量都居世界第一,价格也较便宜。稀土氧化物具有的特殊性质和作用早已引起了催化界的关注。稀土氧化物晶格氧的移动性、顺磁性、表面碱性以及阳离子的可变价与许多催化作用有本质的联系。稀土氧化物不仅本身具有催化性能,而且可作为添加剂和助催化剂,对其他催化剂进行改性,提高催化剂的催化性能。因此,稀土材料作为催化剂在许多化学过程中得到广泛应用。本文以Pr-Zr氧化物固溶体氧化物新型材料为对象,系统研究了其物理化学性质、应用前景。内容包括Pr-Zr氧化物固溶体的制备方法,制备条件对Pr-Zr氧化物固溶体形成的影响,Pr-Zr氧化物固溶体应用于化学链甲烷选择性氧化制合成气的反应性能,介孔Pr-Zr氧化物固溶体制备条件的筛选与优化,介孔Pr-Zr氧化物固溶体为载体制备Au催化剂的设计及其应用于CO氧化反应及碳烟催化燃烧反应性能研究等关键基础问题。为使Pr-Zr复合氧化物具有最佳性能,首先进行Pr-Zr氧化物固溶体的制备并探索得到最佳制备途径,以Pr(N03)3·6H20和Zr(N03)4为前驱盐,制备温度2O℃,pH=12,经过800℃焙烧可制得Pro.7Zro.302-8完全固溶体。将这种方法加以扩展,制备成一系列Pr1-xZrxO2-δ固溶体(x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9)。研究了制备条件对Pr-Zr复合氧化物物化性质的影响,发现制备温度、滴定pH为影响固溶体形成的关键因素。老化温度、母液浓度对完全固溶体形成的影响微弱,但延长老化时间、降低母液浓度可增强复合氧化物的氧活性。发现氧迁移性能是固溶体具有更好氧化还原性质的原因。与纯Pr6O11相比,系列Pr-Zr氧化物固溶体晶粒尺寸明显减小,还原峰温度降低,活性增强。由于其具有较高的储氧量,将Pr1-xZrxO2-δ固溶体应用于化学链选择性氧化甲烷制合成气的反应。考察得出800℃为Pr-Zr复合氧化物选择性氧化甲烷制合成气反应的最合适焙烧温度,850℃为甲烷选择性氧化制合成气反应的最合适反应温度。Pr1-xZrxO2-δ固溶体表现出较高的甲烷转化率及H2、CO选择性,最重要的是具有优异的循环反应稳定性。循环前后材料均保持了固溶体结构,体相晶格氧含量和表面氧空位的增加共同保证了多次循环后反应性能的稳定。在Pr1-xZrxO2-δ固溶体的基础上,进一步提出介孔Pr-Zr氧化物固溶体的制备。通过溶胶凝胶法制备介孔Pr-Zr氧化物固溶体,0.4g/mL的F127为模板剂,Pr(NO3)4和ZrOCl2为前驱盐,乙醇为溶剂,溶胶反应温度控制为40℃,经过恒温恒湿培养,干燥、焙烧即得到产物。考察了制备条件对介孔Pr-Zr复合氧化物形成的影响,认为制备方法,前驱盐种类、溶胶反应温度、模板剂浓度及模板剂种类为制备介孔Pr-Zr复合氧化物的控制因素。对介孔镨锆复合氧化物形成了机理做了探讨,认为此介孔材料是按照协同作用机理进行的。为了考察介孔Pr-Zr氧化物固溶体材料的应用前景,研究了其在CO氧化反应和碳烟催化燃烧反应中的反应性能。作为催化剂Pr-Zr氧化物固溶体依然具有杰出的催化效果,与一般催化剂不同的是,高温老化样品表现出更好的反应结果。进一步将其作为载体,Au为活性组分,制备出Au/Pr-Zr-O复合催化剂。同样将其应用于CO氧化反应和碳烟催化燃烧反应,发现反应中Au与Pr1-xZrxO 2-δ具有协同催化作用。作为载体,Pr-Zr氧化物固溶体具有良好的高温老化性能,大幅提高了催化反应中的反应性能。
[Abstract]:China is a big country of rare earth. The reserves and production of rare earth are both the first and cheaper in the world. The special properties and effects of rare earth oxides have attracted the attention of the catalytic industry. The mobility, paramagnetic, surface alkalinity and cations of rare earth oxide lattice oxygen are essentially related to many catalysis. Oxides not only have catalytic properties, but also can be used as additives and Co catalysts to modify other catalysts to improve the catalytic performance of the catalysts. Therefore, rare earth materials have been widely used as catalysts in many chemical processes. In this paper, a new type of Pr-Zr oxide solid solution oxide material has been studied in this paper. Its physical and chemical properties, application prospects, including the preparation of Pr-Zr oxide solid solution, the effect of preparation conditions on the formation of Pr-Zr oxide solid solution, Pr-Zr oxide solid solution used in chemical chain methane selective oxidation to synthetic gas, screening and optimization of the preparation conditions of mesoporous Pr-Zr oxide solid solution system, mesoporous Pr- The design of the Zr oxide solid solution as the carrier for the preparation of the Au catalyst and its application to the study of the oxidation reaction of CO and the performance of the catalytic combustion of carbon smoke. In order to make the Pr-Zr compound oxide with the best performance, the preparation of the Pr-Zr oxide solid solution and the best way to prepare the Pr-Zr oxide solid solution were first explored, and Pr (N03) 3 6H20 and Zr (N03) 4 were used as the best preparation methods. Precursor salts were prepared at a temperature of 2O, pH=12, and roasted at 800 degrees centigrade to produce Pro.7Zro.302-8 solid solution. This method was extended to prepare a series of Pr1-xZrxO2- [delta] solid solution (x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9). The effect of preparation conditions on the physicochemical properties of Pr-Zr compound oxide was studied. The preparation temperature was found, and the titration pH was the shadow. The key factors for the formation of rounded solid solution. The aging temperature and the concentration of mother liquor have a weak effect on the formation of complete solid solution, but prolonging the aging time and reducing the concentration of the mother solution can enhance the oxygen activity of the compound oxide. It is found that the oxygen transfer performance is the reason for the better redox properties of the solid solution. Compared with the pure Pr6O11, the series of Pr-Zr oxide solid solutions The grain size is obviously reduced, the temperature of the reduction peak is reduced and the activity is enhanced. Because of its high oxygen storage capacity, Pr1-xZrxO2- delta solid solution is applied to the reaction of selective oxidation of methane to synthetic gas in chemical chain. It is found that the optimum calcination temperature for methane synthesis by selective oxidation of methane by Pr-Zr compound oxide at 800 C is the best temperature, and 850 C is one. The most suitable reaction temperature.Pr1-xZrxO2- [delta] solid solution for the reaction of alkane selective oxidation to synthetic gas shows high methane conversion and H2, CO selectivity, and the most important is the excellent stability of the cyclic reaction. The structure of solid solution is maintained in the material before and after the cycle, and the increase of the lattice oxygen content and the surface oxygen vacancy of the body phase ensures a lot. On the basis of Pr1-xZrxO2- delta solution, the preparation of mesoporous Pr-Zr oxide solid solution was further proposed on the basis of Pr1-xZrxO2- delta solution. The solution of mesoporous Pr-Zr oxide solid solution was prepared by sol-gel method, F127 of 0.4g/mL was used as template, Pr (NO3) 4 and ZrOCl2 as precursor salt, ethyl alcohol as solvent, and the sol-gel reaction temperature was controlled to 40 C. The effect of preparation conditions on the formation of mesoporous Pr-Zr compound oxide was investigated. The preparation methods, the type of precursor salt, the temperature of the sol reaction, the concentration of template and the type of template were the control factors for the preparation of mesoporous Pr-Zr compound oxide. The mechanism of the mesoporous praseodymium and zirconium oxide composite oxide was formed. In order to investigate the application prospect of the mesoporous Pr-Zr oxide solid solution materials, the reaction properties of the mesoporous materials were investigated in the CO oxidation reaction and the catalytic combustion of carbon smoke. As a catalyst, Pr-Zr oxide solid solution still has excellent catalytic effect and not with the general catalyst. The same is that the high temperature aging samples showed better reaction results. The Au/Pr-Zr-O composite catalyst was prepared by Au as the carrier and the active component was prepared. It was also applied to the oxidation reaction of CO and the catalytic combustion reaction of carbon smoke. It was found that Au and Pr1-xZrxO 2- Delta have CO catalytic action in the reaction. As a carrier, the solid solution of Pr-Zr oxide solution was used as a carrier. It has good high temperature aging property and greatly improves the reaction performance in catalytic reaction.
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O643.36

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