现代人在日常生活中花在汽车上的时间越来越多,而且车内甲醛的污染可能直接影响人们的身体健康。太阳能热催化氧化技术是净化汽车甲醛的一种潜在方法。以改性共沉淀法制备MnOx-CeO2为主要催化剂,和基本特征(SEM,N2吸附,H2-TPR,UV-可见吸光度)也进行了详细分析。建立了模拟汽车环境中甲醛的太阳能光热催化作用的实验研究。结果表明,实验箱内温度越高(56.7±0.2°C,62.6±0.2°C,68.2±0.2°C),催化降解甲醛效果越好(甲醛降解率:76.2%,78.3%,82.1%)。随着初始甲醛浓度的增加(200ppb,500ppb,1000ppb),催化效果先升高后降低(甲醛降解率:63%,78.3%,70.6%)。随着负载比(10g/m2,20g/m2,40g/m2)的增加,催化效果逐渐上升,甲醛降解率为62.8%,78.3%,和81.1%,分别。根据Eley-Rideal(ER)模型的表达式,Langmuir-Hinshelwood(LH)模型,和Mars-VanKrevelen(MVK)模型,对实验结果进行了拟合和验证,并且发现ER模型具有很高的拟合度。更适合在实验舱中解释MnOx-CeO2催化剂对甲醛的催化机理,其中甲醛处于吸附状态,氧气处于气相。启示:从目前的研究现状来看,车辆已经成为人们不可或缺的出行方式,车内空气质量不容乐观。大多数车辆普遍存在甲醛超标的现象。车内甲醛的特点是持续释放,尤其是在炎热的夏天,车内温度在太阳辐射下急剧上升。此时,甲醛浓度超标4到5倍,这会对乘客的健康造成巨大损害。为了改善车内空气质量,必须采用正确的净化技术来降解甲醛。这种情况带来的问题是如何有效地利用车内太阳辐射和高温来降解车内甲醛。因此,本研究利用热催化氧化技术对夏季汽车高温环境中甲醛进行催化降解。选择的催化剂是MnOx-CeO2,主要是因为氧化锰(MnOx)本身是过渡金属氧化物中挥发性有机化合物(TCO)最有效的催化剂,CeO2具有优异的储氧释放能力和氧化活性,这有助于提高MnOx的活性。最后,温度的影响,对实验中甲醛的初始浓度和催化剂的负载量进行了探索,并分析了MnOx-CeO2催化剂热催化氧化甲醛的动力学模型,为今后该研究在实践中的应用提供技术支持。
Modern people spend more and more time in cars in their daily lives, and the pollution of formaldehyde in the car may directly affect people\'s health. Thermal catalytic oxidation technology by solar light is a potential way to purify formaldehyde in cars. MnOx-CeO2 was prepared by the modified co-precipitation method as the main catalyst, and the basic characteristic (SEM, N2 adsorption, H2-TPR, UV-visible absorbance) were also analyzed in detail. The experimental
study was set up to simulate the solar photothermal catalysis of formaldehyde in-car environment. The results showed that the higher the temperature in the experimental box (56.7 ± 0.2°C, 62.6 ± 0.2°C, 68.2 ± 0.2°C), the better the formaldehyde degradation by catalytic effect (formaldehyde degradation percentage: 76.2%, 78.3%, 82.1%). With increase of the initial formaldehyde concentration (200 ppb, 500 ppb, 1000 ppb), the catalytic effect first increased and then decreased (formaldehyde degradation percentage: 63%, 78.3%, 70.6%). The catalytic effect risen gradually with the increase of load ratio (10g/m2, 20g/m2, and 40g/m2), and the formaldehyde degradation percentages were 62.8%, 78.3%, and 81.1%, respectively. According to the expressions of the Eley-Rideal (ER) model, the Langmuir-Hinshelwood (LH) model, and the Mars-Van Krevelen (MVK) model, the experimental results were fitted and verified, and it was found that the ER model had a high degree of fit. It is more suitable to explain the catalytic mechanism of formaldehyde by MnOx-CeO2 catalyst in the experimental cabin, where formaldehyde is in the adsorption state and oxygen is in the gas phase.Implications: Judging from the current research status, vehicles have become an indispensable mode of travel for people, and the air quality in the vehicle is not optimistic. Most vehicles generally have the phenomenon of excessive formaldehyde. The characteristic of formaldehyde in the car is the continuous release, especially in the hot summer, the temperature inside the car rises sharply under the sun radiation. At this time, the formaldehyde concentration exceeds the standard by 4 to 5 times, which can cause great damage to the health of the passengers. In order to improve the air quality in the car, it is necessary to adopt the correct purification technology to degrade formaldehyde. The problem brought by this situation is how to effectively use solar radiation and high temperature in the car to degrade formaldehyde in the car. Therefore, this
study uses the thermal catalytic oxidation technology to catalyze the degradation of formaldehyde in the high temperature environment of the car in summer. The selected catalyst is MnOx-CeO2, mainly because manganese oxide (MnOx) itself is the most effective catalyst for volatile organic compounds (TCO) among transition metal oxides, and CeO2 has excellent oxygen storage and release capacity and Oxidation activity, which helps to improve the activity of MnOx. Finally, the effects of temperature, initial concentration of formaldehyde and catalyst loading on the experiment were explored, and the kinetic model of thermal catalytic oxidation of formaldehyde with MnOx-CeO2 catalyst was analyzed to provide technical support for the future application of this research in practice.