【作者】 杜菲菲；

【导师】 谭欣；

【作者基本信息】 天津大学 ， 环境科学， 2010， 硕士

【摘要】 CO₂的减排问题是目前各个国家及不同领域研究和探讨的最重要议题之一,利用光催化反应还原CO₂合成低碳有机物具有重要的理论及现实意义,但是其反应的转化效率比较低,这也是研究人员长久以来研究的重点和努力解决的问题。本文一方面通过对TiO₂光催化剂进行材料改性,另一方面则通过对反应条件的优化,以提高光催化还原CO₂的效率,并对反应机理进行初步探讨。本文采用溶胶凝胶法制备TiO₂纳米粉体,并选择La、Nd、Y三种稀土元素对其进行掺杂改性,并且制备出稀土与铜共掺改性,与CuO复合共改性TiO₂纳米粉体,进行光催化还原CO₂的反应,研究掺杂的稀土元素种类和添加量,以及不同的改性方法对TiO₂光催化还原性能的影响。对改性材料进行XRD、TEM、XPS表征,分析其晶相结构、形貌及组分价态,并以光催化还原CO₂反应产物甲醛的生成量来评价催化剂的活性。结果表明,改性TiO₂经500℃煅烧后主要为锐钛矿型,晶粒粒径较小,具有良好的光催化活性。不同稀土元素改性效果La>Nd>Y,最佳的稀土元素添加量为0.1wt.%。以La为研究对象,不同的改性方法改性效果La-CuO/TiO₂>La-TiO₂>La/Cu-TiO₂。最优的催化剂为0.1wt.%的La-CuO/TiO₂,还原产物甲醛的生成量为953.53μmol/g·cat.。本文进一步研究了光催化还原CO₂的最佳反应条件,考察了光照时间、溶液初始pH值、通入的CO₂体积流量以及空穴捕获剂的添加量这四方面因素对CO₂光催化还原反应的影响。研究结果表明,在本实验条件下,光催化还原CO₂反应的最佳条件如下:光照时间为6h,溶液初始pH值为10,反应过程中通入的CO₂的体积流量为30mL/min,空穴捕获剂甲醇的添加量为1.0mol/L。更多还原

【Abstract】 CO₂ emission reduction is one of the most important issues among different countries and various areas. Photocatalytic reduction of CO₂ to synthesis low-carbon organic matter has theoretical and practical significance. But conversion efficiency of the reaction is relatively low, which is the problem researchers have been focused on for a long time. In this study, we synthesized a series of rare earth （RE） and copper modified TiO₂ nano-photocatalysts to evaluate the activities of CO₂ photoreduction. Further more, we optimized the reaction conditions to improve the reaction efficiency.TiO₂ nano-particles were synthesized by sol-gel method. The RE （La, Nd, Y） doped, the RE and copper co-doped and CuO composite modified TiO₂ nano-particles were prepared for photocatalytic reduction of CO₂. The prepared particles were characterized using XRD, TEM, and XPS. And the activities of the photocatalysts were estimated by the yield of formaldehyde. The results showed that the modified TiO₂ nano-particles had better activities and smaller crystal grain size than the bare TiO₂. The comparison of catalytic efficiency between different rear earth doped materials showed La>Nd>Y, and the best doping amount was 0.1wt.%. Regarding La as the research subject, the catalytic efficiency varied by changing the modification method, which showed La-CuO/TiO₂>La-TiO₂>La/Cu-TiO₂. The best photocatalyst was La-CuO/TiO₂ with La doping amount of 0.1wt.%, and the yield of formaldehyde was 953.53μmol/g·cat..This research further investigated the optimum conditions of photocatalytic reduction of CO₂, including illumination time, initial pH value of reaction solution, CO₂ flow rate and the addition amount of hole scavenger. The results showed that the optimum conditions of CO₂ photoreduction were as follows: illumination time was 6h, pH value was 10, CO₂ flow rate was 30mL/min, and addition amount of methanol was 1.0mol/L.更多还原