臭氧催化氧化脱除低浓度甲醛的新方法（英文）

发布时间：2018-01-16 08:05

本文关键词：臭氧催化氧化脱除低浓度甲醛的新方法（英文）　出处：《催化学报》2017年10期 　论文类型：期刊论文

【摘要】：甲醛作为一种典型的室内挥发性有机污染物,对人体健康危害很大.目前,在可用于室内甲醛脱除的诸多方法之中,臭氧催化氧化法因可于室温下使用廉价的金属氧化物催化剂实现对甲醛的高效脱除,从而受到了科研工作者的广泛关注.然而,考虑到室内甲醛的浓度极低,且存在着长期缓慢释放的特点,传统的臭氧催化氧化法应用于实际的室内甲醛脱除不仅会造成能量的浪费,而且还易因未完全分解臭氧的连续释放带来二次污染问题.为了提高臭氧催化氧化脱除甲醛过程的臭氧利用率,降低能耗,并有效缓解未分解臭氧引起的二次污染,本文将一种循环的甲醛存储-臭氧催化氧化新方法应用于室内低浓度甲醛的脱除.该新方法包含甲醛存储与臭氧催化氧化两个过程,在存储阶段低浓度甲醛吸附存储于催化剂表面,而在臭氧催化氧化阶段臭氧将存储的甲醛氧化为CO_2与H_2O,并重新释放催化剂表面的吸附位.因负载型氧化锰具有优良的臭氧分解能力,本研究以Al_2O_3负载的MnO_x为催化剂,通过研究前驱体及担载量对甲醛脱除反应的影响,筛选出了最优的MnO_x/Al_2O_3催化剂,并对相对湿度的影响规律进行了考察,最后通过低浓度甲醛存储-臭氧催化氧化循环实验验证了该甲醛臭氧催化氧化新过程的可靠性.我们采用传统的等体积浸渍法,基于不同的前驱体制备MnO_x/Al_2O_3催化剂.XRD表征结果表明,乙酸锰为前驱体制得的MA/Al_2O_3催化剂中MnO_x相主要为Mn3O4(粒径约为6.0 nm);而硝酸锰前驱体所得MN/Al_2O_3催化剂中则含有MnO2与Mn_2O_3相,且其MnO_x颗粒粒径较大,约为9.5 nm.XPS测试结果表明,MA/Al_2O_3催化剂含有Mn~(2+),Mn~(3+)及Mn~(4+),其中Mn~(3+)与Mn~(4+)的含量分别为75%与12%;而MN/Al_2O_3催化剂则仅含有Mn~(3+)与Mn~(4+),含量分别为35%与65%.上述XRD与XPS结果相一致,说明以乙酸锰为前驱体所得催化剂的分散度较高且易形成低氧化态的Mn.甲醛存储-臭氧催化氧化实验结果表明,与Al_2O_3及MN/Al_2O_3相比,MA/Al_2O_3催化剂具有更高的甲醛存储与催化氧化脱除性能.基于MA/Al_2O_3催化剂,不同Mn负载量下的甲醛存储与臭氧催化氧化实验结果表明,Mn负载量为10 wt%时MA/Al_2O_3的性能最佳.因而,进一步的实验中我们均选用最优的10 wt%MA/Al_2O_3为催化剂,其在50%相对湿度下的甲醛存储量为26.9μmol/mL,臭氧催化氧化阶段碳平衡为92%,CO_2选择性为100%.相对湿度的影响结果(23°C)则表明,由于水分子与甲醛分子间存在着竞争吸附作用,甲醛存储容量随相对湿度的增加而降低;但因相对湿度增加可建立利于甲醛氧化的新途径,故臭氧催化氧化性能随相对湿度增加而增强.综合考虑,10 wt%MA/Al_2O_3上甲醛存储-臭氧催化氧化的最优相对湿度为50%.为验证所提出新方法的实用性,我们基于10 wt%MA/Al_2O_3开展了甲醛存储-臭氧催化氧化的4次循环实验.4次循环实验中的甲醛存储以及臭氧催化氧化处理的规律可基本保持一致.50%相对湿度下,低浓度甲醛(15×10-6)在空速为27000 h-1时的穿透时间为110 min,而在臭氧催化氧化阶段(150×10-6臭氧,空速15000 h-1)仅需约50 min即可实现对存储甲醛的氧化脱除(碳平衡大于92%,CO_2选择性100%),表明该新方法较传统的臭氧催化氧化方法臭氧用量可节省60%.
[Abstract]:Formaldehyde as a typical indoor volatile organic pollutants, great harm to human health. At present, many methods can be used in indoor formaldehyde removal, catalytic ozonation Fayinke at room temperature using cheap metal oxide catalysts for efficient removal of formaldehyde, which attracted the attention of researchers. However, considering the very low concentration of indoor formaldehyde, and there exists long-term slow release, the traditional ozone catalytic oxidation method is applied to the actual removal of indoor formaldehyde will not only cause the waste of energy, but also due to the incomplete decomposition of ozone for the release of two pollution problems. In order to improve the ozone catalytic oxidation of formaldehyde utilization process, reduce energy consumption, and effectively alleviate the two pollution not caused by the decomposition of ozone, a cyclic formaldehyde storage catalytic ozonation NEW The removal methods applied to low concentration of formaldehyde in the indoor. The new method includes formaldehyde storage and ozone oxidation of two processes in the storage stage of low concentration formaldehyde adsorption storage on the surface of the catalyst in the catalytic ozonation stage of ozone oxidation of formaldehyde storage for CO_2 and H_2O, and re release adsorbed. Because of the load manganese oxide has excellent ozone decomposition ability, in this study, Al_2O_3 supported MnO_x as catalyst, through the study of precursor and loading effect on the removal of formaldehyde, MnO_x/Al_2O_3 were screened out the optimal catalyst, and the influence of relative humidity were studied. Finally, through the low concentration formaldehyde storage - ozone catalytic oxidation the experiment verifies the reliability of the new recycling process of the formaldehyde catalytic ozonation. We adopt the traditional impregnation method, the preparation of MnO_x/ Al_2 based on different precursor O_3.XRD catalyst characterization results showed that manganese acetate as precursors of MnO_x MA/Al_2O_3 catalyst in the main phase was Mn3O4 (diameter 6 nm); and the nitrate precursor MN/Al_2O_3 catalyst contains MnO2 and Mn_2O_3, and the MnO_x particle size is large, about 9.5 of the nm.XPS test results showed that MA/Al_2O_3 catalyst containing Mn~ (2+), Mn~ (3+) and Mn~ (4+), Mn~ (3+) and Mn~ (4+) content were 75% and 12%; and the MN/Al_2O_3 catalyst containing only Mn~ (3+) and Mn~ (4+), the content is 35% and 65%. respectively the XRD and XPS results are consistent. With manganese acetate as precursor of the catalyst dispersion is high and easy to form a low oxidation state Mn. formaldehyde storage catalytic ozonation experiment results show that compared with Al_2O_3 and MN/Al_2O_3, the MA/Al_2O_3 catalyst has higher formaldehyde storage and catalytic oxidation removal performance. Based on the MA/Al_2O_3. Agent Mn, different load storage and ozone oxidation of formaldehyde under the experimental results show that the loading of Mn was the best performance of MA/Al_2O_3 10 wt%. Therefore, further experiments we choose the optimum wt%MA/Al_2O_3 10 as catalyst, the amount of storage of formaldehyde in 50% relative humidity is 26.9 mol/mL, catalytic ozonation the oxidation stage carbon balance was 92%, the selectivity of CO_2 for the effect of 100%. relative humidity (23 degrees C) indicates that, because the water molecules and formaldehyde molecules exist between the competitive adsorption of formaldehyde, storage capacity decreases with the increase of relative humidity; but because of the increase of relative humidity can be set up new ways to formaldehyde oxidation, so the ozone catalytic oxidation performance increases with the increase of relative humidity. Considering the 10 wt%MA/Al_2O_3 optimal storage formaldehyde - ozone catalytic oxidation of relative humidity is 50%. for the new proposed method is verified by us. 10 wt%MA/Al_2O_3 to carry out storage - ozone oxidation of the formaldehyde 4 cycle experiment of.4 cycles in the experiment of formaldehyde storage and ozone catalytic oxidation rules consistent with.50% relative humidity on formaldehyde in low concentration (15 * 10-6) in airspeed is 27000 H-1 when the breakthrough time was 110 min, while the ozone catalytic oxidation stage (150 10-6 * 15000 H-1 ozone, airspeed) only about 50 min can be realized on the oxidative removal of formaldehyde (storage of carbon balance is greater than 92%, the selectivity of CO_2 100%), indicating that the ozone catalytic oxidation method, the new method is better than the traditional ozone dosage can save 60%.

【作者单位】：大连海事大学船舶防污染测控技术协同创新中心;大连理工大学等离子体物理化学实验室;大连理工大学氢能与环境催化研究中心;
【基金】：supported by the National Natural Science Foundation of China(21673030) the Higher Education Development Fund(for Collaborative Innovation Center) of Liaoning Province,China(20110217004)~~
【分类号】：O643.36;X51
【正文快照】： 1.IntroductionIndoor air quality has become a serious issue owing to theincreasing amount of time people spent indoors.Formaldehyde(HCHO)is a common volatile organic compound(VOC)presencein indoor air,which poses serious risks to human health[1,2].Thus,r

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