OMS-2催化剂的制备和催化分解臭氧的性能研究

发布时间：2018-04-16 12:20

本文选题：OMS-2 + Ce-OMS-2　；参考：《北京化工大学》2015年硕士论文

【摘要】：众所周知,对于人类赖以生存环境而言,臭氧起到双刃剑的作用。在平流层,臭氧能够抵挡紫外线直接照射地球,是大自然的天然保护屏障；然而在靠近地表处,臭氧的危害作用十分大,会对人体的皮肤,免疫系统以及神经系统等产生不同程度的影响。近地表的臭氧主要来源于水处理的尾气和打印机等办公设备。催化分解臭氧方法由于其安全、经济、高效的特点,受到广泛关注,其中锰氧化物是最有效的去除臭氧的催化剂。隐锰钾矿(OMS-2)是一种由[Mn06]八面体链内共棱,链间共顶角氧构筑的孔径为0.46nm的一维孔架结构的锰氧化物。OMS-2骨架中存在不同价态的锰离子,能提供较大的比表面积以及较高的抗湿性能,有利于臭氧的催化分解。本文采用水热合成的方法制备了一系列OMS-2和金属掺杂的M-OMS-2催化剂,并考察了其高湿度条件下对臭氧的分解性能。通过XRD、 Raman、XAFS、BET、SEM、H2-TPR和ICP等表征手段对催化剂进行了结构和性能表征。结果表明：在单组分OMS-2催化剂中,采用乙酸锰为前驱体合成的OMS-2-Ac催化剂在相对湿度为90%的条件下,表现出比较优越的臭氧催化活性,转化率为80%左右,性能优于以硝酸锰合成的OMS-2-NO3和以氯化锰合成的OMS-2-Cl催化剂。合成过程中乙酸根的存在能够阻止锰氧化物粒子之间的聚集,提供更多的表面缺陷位,OMS-2-Ac催化剂表面丰富的Mn3+是催化剂性能优越的关键因素。在金属掺杂的M-OMS-2催化剂中,以硝酸铈铵为前驱体合成Ce-OMS-2催化剂具有最优的臭氧分解性能,在相对湿度为90%条件下,6小时内臭氧的转化率基本为100%。与其他Co-OMS-2、Ni-OMS-2、Cu-OMS-2和Fe-OMS-2催化剂相比较,Ce-OMS-2的结构发生畸变,Mn-Mn的配位不完全,有较大的比表面积,能够暴露更多的表面活性位；催化剂表面具有丰富的Mn3+和表面氧,有利于02*的脱附,促进臭氧的分解。Ce-OMS-2催化剂在相对湿度为90%,体积空速高达600000h-1的条件下,表现出优越的臭氧催化分解活性,因此对于高浓度臭氧尾气的处理具有很高的应用价值。
[Abstract]:As we all know, ozone plays a double-edged role for human living environment.In the stratosphere, ozone acts as a natural protective barrier to nature by shielding itself from direct ultraviolet radiation; however, near the surface, ozone is so harmful that it does harm to the skin of the human body.The immune system and the nervous system have varying degrees of influence.Ozone near the surface mainly comes from exhaust gas from water treatment and office equipment such as printers.The catalytic decomposition of ozone has attracted much attention because of its safety, economy and efficiency. Manganese oxide is the most effective catalyst for ozone removal.OMS-2) is a manganese ion with different valence states in the framework of manganese oxide. OMS-2, which is constructed by co-edged in [Mn06] octahedron chain and coparietal oxygen between chains, has a one-dimensional pore structure of 0.46nm.It can provide large specific surface area and high moisture resistance, which is beneficial to the catalytic decomposition of ozone.In this paper, a series of OMS-2 and metal-doped M-OMS-2 catalysts were prepared by hydrothermal synthesis.The structure and properties of the catalyst were characterized by XRD, Ramanlum ICP, BETS, SEMX, H2-TPR and ICP.The results showed that the OMS-2-Ac catalyst synthesized with manganese acetate as precursor showed superior ozone catalytic activity under 90% relative humidity, and the conversion rate was about 80%.The performance of the catalyst is superior to that of OMS-2-NO3 synthesized by manganese nitrate and OMS-2-Cl synthesized by manganese chloride.In the process of synthesis, the presence of acetate can prevent the aggregation of manganese oxide particles, and providing more surface defect sites and abundant Mn3 on the surface of OMS-2-Ac catalyst is the key factor for the superior performance of the catalyst.In the metal-doped M-OMS-2 catalyst, the synthesis of Ce-OMS-2 catalyst with ammonium cerium nitrate as the precursor has the best ozone decomposition performance, and the conversion rate of ozone is almost 100 in 6 hours under 90% relative humidity.Compared with other Co-OMS-2Ni-OMS-2Mo Cu-OMS-2 and Fe-OMS-2 catalysts, the structure of Ce-OMS-2 is distorted. The coordination of Ce-OMS-2 is incomplete and has a larger specific surface area, which can expose more surface active sites, and the surface of the catalyst is rich in Mn3 and surface oxygen, which is conducive to the desorption of 0.2 *.Ce-OMS-2 catalyst for promoting the decomposition of ozone has excellent catalytic activity of ozone decomposition under the condition of 90 relative humidity and high volume space velocity (600000h-1), so it has a high application value for the treatment of high concentration ozone tail gas.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;O643.36

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