氧化铈基材料的制备及光催化脱硝性能研究

发布时间：2018-05-05 09:33

本文选题：纳米氧化铈 + 石墨烯　；参考：《江苏大学》2017年硕士论文

【摘要】：工业废气和汽车发动机尾气中所含的大量氮氧化物不仅会对人体造成一次伤害,更将形成酸雨以及光化学烟雾。因此,开发高效脱硝催化剂脱除氮氧化物,遏制雾霾的产生,发展绿色循环经济,构建环境与经济的协调发展已经刻不容缓。本课题针对这一现状选取富含分级多孔结构的生物组织作为模板,利用生物大分子的诱导作用获取结构不同的仿生纳米光催化材料。研究氧空位在导向光还原中起的关键作用;揭示光催化材料的微观结构-氧空位浓度-导向光还原性能三者之间的内在关系。通过设计对比实验,指导仿生纳米复合光催化剂材料的设计。使用不同的生物模板及预处理方法、调控与氧化铈纳米颗粒复合的碳材料,搭建模拟光还原脱除废气反应装置,在不同温度、不同光强、不同气流空速下利用制得的催化材料转化模拟工业废气,揭示仿生富集的分级多孔结构对氮氧化物导向光还原速率及反应产物的影响规律。本课题以新鲜豆芽,螺旋藻,油菜茎杆富含分级多孔结构的组织作为生物模板制备仿生纳米CeO_2/石墨烯光催化剂,在烧结温度为800°C,煅烧速率为2°C/min条件下,仿生CeO_2/石墨烯纳米催化剂精确复制了生物模板的微观形貌特征。经荧光显微镜、X射线衍射、拉曼、氮气吸附脱吸仪、电子显微镜、紫外漫散射表征后可知仿油菜茎杆形貌的CeO_2/石墨烯光催化材料其孔隙结构更为均匀,晶粒尺寸更小,精确复制了其具有的分级多孔结构,继承了油菜茎杆模板高孔隙率,超大比表面积及易于调控的微观形貌特征,有效地增强了所制备的纳米光催化剂对可见光的捕获能力,显著提高了材料的光催化活性,为光催化脱硝提供了良好的催化环境。通过实验探究出最佳光催化低温脱除氮氧化物条件,最佳纳米光催化剂的生物模板即仿油菜茎杆形貌的CeO_2/石墨烯在煅烧温度为800°C、煅烧速率为2°C/min、催化剂填充体积为6 m L、NO浓度为600 ppm、氨气浓度为600 ppm、氮气为载气、反应温度为140°C、空速为1000 h-1时催化剂的脱硝效率达到最高,对NO的催化脱除效率达到87%。
[Abstract]:Industrial exhaust and a large amount of nitrogen oxides in automobile engine exhaust will not only cause a damage to the human body, but also form acid rain and photochemical smog. Therefore, it is urgent to develop high efficiency denitrification catalyst to remove nitrogen oxides, to contain the production of haze, to develop green circular economy and to build a coordinated development of environment and economy. In order to solve this problem, biomimetic nano-photocatalytic materials with different structure were obtained by using biological macromolecules as template. The key role of oxygen vacancy in guided photoreduction is studied, and the relationship between microstructure, oxygen vacancy concentration and photoreduction performance of photocatalytic materials is revealed. The design of biomimetic nano-composite photocatalyst material was guided by the design and contrast experiment. Different biological templates and pretreatment methods were used to control the carbon composite with cerium oxide nanoparticles, and the simulated photoreduction and removal of waste gas reaction device was set up at different temperatures and different light intensities. The catalytic materials prepared under different airflow velocities were used to simulate industrial waste gas, which revealed the effect of bionic enrichment of porous structure on the photoreduction rate and reaction products of nitrogen oxides. In this paper, the biomimetic nanometer CeO_2/ graphene photocatalyst was prepared by using fresh bean sprouts, spirulina and rape stems as biomimetic templates, which were rich in graded porous structures. The sintering temperature was 800 掳C and the calcination rate was 2 掳C/min. The biomimetic CeO_2/ graphene nanocatalyst accurately duplicates the microscopic morphology of the biological template. X-ray diffraction, Raman, nitrogen adsorption-desorption apparatus, electron microscope and ultraviolet diffuse scattering analysis showed that the CeO_2/ graphene photocatalytic material, which mimic the morphology of rape stem, had more uniform pore structure and smaller grain size. The high porosity, large specific surface area and easy to control micromorphology of rape stem template were inherited, which effectively enhanced the ability of the prepared nano-photocatalyst to capture the visible light, so that it could accurately reproduce the hierarchical porous structure, and inherit the characteristics of high porosity, large specific surface area and easy to adjust and control the microscopic morphology of rape stem template. The photocatalytic activity of the material was improved significantly, which provided a good catalytic environment for photocatalytic denitrification. The optimum conditions of photocatalytic removal of nitrogen oxides at low temperature were investigated by experiments. The best biological template of nano-photocatalyst, CeO_2/ graphene, which mimics the morphology of rape stem, is calcined at 800 掳C, calcination rate is 2 掳C / min, the volume of catalyst filling is 600ppm, ammonia is 600ppm, nitrogen is carrier gas. When the reaction temperature is 140 掳C and the space velocity is 1000 h ~ (-1), the denitrification efficiency of the catalyst is the highest, and the catalytic removal efficiency of no is 87%.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X701;O643.36

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