大气污染物CO和NO_X清除—新型纳米多孔催化材料的合成

发布时间：2018-02-22 12:37

  本文关键词： NOx选择性还原和CO氧化 Sn和Cu分子筛 多形貌SnO2和ZnO 构效关系 限域效应　出处：《南昌大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,随着科学技术的日新月异,人们的生活水平不断提高,然而不洁净使用能源所带来的环境污染却愈来愈严重。大气污染物中NOx和CO是两类有毒有害气体,消除它们的排放迫在眉睫。选择性催化还原和催化氧化分别是消除NOx与CO排放的有效方法。本论文主要研究和探讨NOx和CO净化催化剂的设计与制备。第一部分首先研究了Sn-MFI分子筛的NOx催化脱除性能。研究结果表明,Sn离子成功掺杂进入MFI分子筛骨架结构中。Sn-MFI具有规整的形貌和结构,而且结构中含有微孔-介孔多级孔道。同时Sn-MFI表面由于Sn离子介入形成大量的路易斯酸中心和表面活泼氧,因此,Sn-MFI具有良好的NOx选择性还原活性和优良的抗水和抗硫性能。为进一步提高Sn-MFI的活性,第二部分着重研究了Sn-ZSM-5分子筛的NOx催化脱除性能。结果表明,相较于Sn-MFI分子筛,由于Al引入骨架,Sn-ZSM-5催化剂中形成了新的酸中心,且其酸性得到进一步提高,因此,Sn-ZSM-5分子筛的NOx选择性还原活性优于Sn-MFI分子筛。论文的第三部分研究了片状Cu-MFI分子筛的NOx催化脱除性能。结果表明,所制备的Cu-MFI纳米片为形貌比较规整的纳米片状结构,具有微孔-介孔多级孔道结构。随着Cu含量的提高,反应活性不断增强,最优转化NOx温度窗口也相应加宽。论文第四部分制备了多形貌SnO2纳米新材料,然后应用于CO催化氧化中,研究多形貌纳米材料的构效关系。研究结果表明,SnO2纳米片具有高的比表面积、丰富的疏松的孔道、大量的表面活泼氧物种,因而具有优良的CO催化氧化活性,260 oC可将CO完全转化。SnO2单晶纳米棒虽然比表面积只有1 m2g-1,但是由于其(110)活泼晶面优先暴露,因此催化活性也大大提高,而且具有类贵金属催化行为和机理,280 oC时可将CO完全转化,并且在240-260 oC范围内出现明显的反应突跃。论文第五部分合成了ZnO纳米管、纳米片、纳米棒和星型结构,探讨ZnO纳米材料的构效关系。研究结果表明,与常规ZnO纳米粉末相比,片状ZnO的比表面积高达41 m2g-1,体相中存在大量的疏松孔道结构,对CO催化氧化具有很高的活性,在300 oC时即可将CO完全转化。ZnO纳米棒的比表面积仅为3 m2g-1,但是由于形成比较严整的单晶棒状结构,改变了材料本来的电子性质和催化机理,催化活性大大提高,在280 oC时可将CO完全转化,而且在260-280 oC范围内出现了明显的反应突跃,具有类贵金属反应行为和机理。论文第六部分制备了纤维状介孔SiO2(KCC-1)限域的CuO纳米粒子,并应用于NOx选择性还原和CO氧化方面。研究表明,Cu-KCC-1对NOx选择性还原和CO氧化都具有很高的催化活性。其活性中心为高度分散在KCC-1纤维状结构的表面、粒径在10 nm以下的CuO颗粒,因而所得材料具有优异的催化活性。
[Abstract]:In recent years, with the rapid development of science and technology, people's standard of living has been improved. However, the environmental pollution caused by the unclean use of energy is becoming more and more serious. NOx and CO are two kinds of toxic and harmful gases in the air pollutants. It is urgent to eliminate their emission. Selective catalytic reduction and catalytic oxidation are the effective methods to eliminate NOx and CO emissions respectively. The design and preparation of NOx and CO purification catalysts are studied and discussed in this paper. The first part is about the design and preparation of NOx and CO purification catalysts. The catalytic removal of Sn-MFI molecular sieve by NOx was studied. The results showed that Sn-MFI had regular morphology and structure in the skeleton structure of MFI molecular sieve. Moreover, there are micropore-mesoporous multistage channels in the structure. At the same time, a large number of Lewis acid centers and active oxygen are formed on the surface of Sn-MFI due to the involvement of Sn ions. Therefore, Sn-MFI has good NOx selective reduction activity and excellent water and sulfur resistance. In order to further improve the activity of Sn-MFI, the second part focuses on the study of NOx catalytic removal performance of Sn-ZSM-5 molecular sieve. The results show that, compared with Sn-MFI molecular sieve, Due to the introduction of Al into the framework Sn-ZSM-5 catalyst, a new acid center was formed, and its acidity was further improved. Therefore, the NOx selective reduction activity of Sn-ZSM-5 molecular sieve is superior to that of Sn-MFI molecular sieve. In the third part of this paper, the NOx catalytic removal performance of the flake Cu-MFI molecular sieve was studied. With the increase of Cu content, the reaction activity increases, and the temperature window of the optimal conversion NOx is widened accordingly. In the 4th part of the thesis, new multi-morphologies SnO2 nanomaterials were prepared. Then it was applied to CO catalytic oxidation to study the structure-activity relationship of multi-morphologies nanomaterials. The results showed that Sno _ 2 nanocrystals had high specific surface area, abundant porous pores and a large number of active oxygen species on the surface. Therefore, with excellent catalytic oxidation activity of CO, 260oC can completely transform CO into 路SnO2 nanorods, although the specific surface area of nanorods is only 1m2g-1, but because of the preferential exposure of their active crystal planes, the catalytic activity is also greatly improved. In addition, the ZnO nanotubes, nanorods, nanorods and starlike structures were synthesized in the 5th part of the thesis, and the CO was completely converted to CO at 280oC with noble metal catalytic behavior and mechanism, and the apparent reaction occurred in the range of 240-260oC. in the 5th part of the thesis, ZnO nanotubes, nanorods, nanorods and star structures were synthesized. The structure-activity relationship of ZnO nanomaterials was studied. The results showed that compared with conventional ZnO nano-powders, the specific surface area of flake ZnO was up to 41 m ~ (-2) g ~ (-1), and there were a large number of porous pore structures in bulk phase, which had high activity for CO catalytic oxidation. The specific surface area of ZnO nanorods was only 3m2g-1 when CO was completely transformed at 300oC. However, due to the formation of a more precise single crystal rod structure, the original electronic properties and catalytic mechanism of the materials were changed, and the catalytic activity was greatly improved. CO can be completely converted at 280oC, and there is a sharp jump in the range of 260-280oC, which has noble metal reaction behavior and mechanism. In the 6th part of this paper, CuO nanoparticles with the limited range of fibrous mesoporous SiO2KCC-1 have been prepared. The results show that Cu-KCC-1 has high catalytic activity for NOx selective reduction and CO oxidation. The active center of Cu-KCC-1 is highly dispersed on the surface of KCC-1 fibrous structure and the particle size is less than 10 nm. Therefore, the obtained material has excellent catalytic activity.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;TQ426

【共引文献】

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