Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
J Air Waste Manag Assoc. 2023 May;73(5):345-361. doi: 10.1080/10962247.2023.2179685.
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. MnO-CeO was prepared by the modified co-precipitation method as the main catalyst, and the basic characteristic (SEM, N adsorption, H-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 , 500 , 1000 ), 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 (10, 20, and 40), 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 MnO-CeO catalyst in the experimental cabin, where formaldehyde is in the adsorption state and oxygen is in the gas phase.: 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 MnO-CeO, mainly because manganese oxide (MnO) itself is the most effective catalyst for volatile organic compounds (TCO) among transition metal oxides, and CeO has excellent oxygen storage and release capacity and Oxidation activity, which helps to improve the activity of MnO. 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 MnO-CeO catalyst was analyzed to provide technical support for the future application of this research in practice.
现代人在日常生活中越来越多地在汽车中花费时间，车内甲醛污染可能直接影响人们的健康。通过太阳能光热催化氧化技术净化车内甲醛是一种很有前途的方法。本研究采用改进的共沉淀法制备了 MnO-CeO 为主催化剂，并详细分析了其基本特性（SEM、N 吸附、H-TPR、UV-可见吸收）。建立了实验装置，模拟车内环境的太阳能光热催化甲醛。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），催化效果越好（甲醛降解率：76.2%、78.3%、82.1%）。随着初始甲醛浓度（200、500、1000）的增加，催化效果先增加后降低（甲醛降解率：63%、78.3%、70.6%）。随着负载比（10、20、40）的增加，催化效果逐渐升高，甲醛降解率分别为 62.8%、78.3%和 81.1%。根据 Eley-Rideal（ER）模型、Langmuir-Hinshelwood（LH）模型和 Mars-Van Krevelen（MVK）模型的表达式，对实验结果进行了拟合和验证，发现 ER 模型拟合度较高。更适合解释 MnO-CeO 催化剂在实验舱内催化甲醛的反应机理，其中甲醛处于吸附态，氧气处于气相。
从目前的研究现状来看，汽车已成为人们不可或缺的出行方式，车内空气质量不容乐观。大多数车辆一般都存在甲醛过量的现象。车内甲醛的特点是持续释放，尤其是在炎热的夏季，在太阳辐射下车内温度急剧上升。此时，甲醛浓度超标 4 至 5 倍，对乘客健康造成极大危害。为了改善车内空气质量，需要采用正确的净化技术来降解车内甲醛。由此带来的问题是如何有效利用车内太阳能辐射和高温来降解车内甲醛。因此，本研究采用热催化氧化技术在夏季车内高温环境下催化降解甲醛。所选催化剂为 MnO-CeO，主要是因为二氧化锰（MnO）本身是过渡金属氧化物中最有效的挥发性有机化合物（TCO）催化剂，CeO 具有优异的储氧和释放能力以及氧化活性，有助于提高 MnO 的活性。最后，考察了温度、甲醛初始浓度和催化剂负载量对实验的影响，并对 MnO-CeO 催化剂热催化氧化甲醛的动力学模型进行了分析，为该研究在未来实际应用中提供了技术支持。
