Abstract：
Formaldehyde (FA) is a hazardous indoor air pollutant with carcinogenic propensity. Oxidation of FA in the dark at low temperature (DLT) is a promising strategy for its elimination from indoor air. In this light, binary manganese-cobalt oxide (0.1 to 5 mol L-1-MnCo2O4) is synthesized and modified in an alkaline medium (0.1-5 mol L-1 potassium hydroxide) for FA oxidation under room temperature (RT) conditions. Accordingly, 1-MnCo2O4 achieves 100 % FA conversion at RT (50 ppm and 7022 h-1 gas hourly space velocity (GHSV)). The catalytic activity of 1-MnCo2O4 is assessed further as a function of diverse variables (e.g., catalyst mass, relative humidity, FA concentration, molecular oxygen (O2) content, flow rate, and time on-stream). In situ diffuse reflectance infrared Fourier-transform spectroscopy confirms that FA molecules are adsorbed onto the active surface sites of 1-MnCo2O4 and oxidized into water (H2O) and carbon dioxide (CO2) through dioxymethylene (DOM) and formate (HCOO-) as the reaction intermediates. According to the density functional theory simulations, the higher catalytic activity of 1-MnCo2O4 can be attributed to the combined effects of its meritful surface properties (e.g., the firmer attachment of FA molecules, lower energy cost of FA adsorption, and lower desorption energy for CO2 and H2O). This work is the first report on the synthesis of alkali (KOH)-modified MnCo2O4 and its application toward the FA oxidative removal at RT in the dark. The results of this study are expected to provide valuable insights into the development of efficient and cost-effective non-noble metal catalysts against indoor FA at DLT.
摘要：
甲醛（FA）是一种具有致癌倾向的有害室内空气污染物。在低温（DLT）下黑暗中FA的氧化是消除室内空气中FA的一种有前途的策略。在这种情况下，在碱性介质（0.1-5molL-1氢氧化钾）中合成并改性二元锰钴氧化物（0.1至5molL-1-MnCo2O4），用于在室温（RT）条件下进行FA氧化。因此，1-MnCo2O4在RT下实现100%FA转化率(50ppm和7022h-1气时空速(GHSV))。1-MnCo2O4的催化活性进一步评估为不同变量的函数（例如，催化剂质量，相对湿度,FA浓度,分子氧(O2)含量,流量,和时间在流)。原位漫反射红外傅里叶变换光谱证实，FA分子吸附到1-MnCo2O4的活性表面位点上，并通过二甲醛（DOM）和甲酸（HCOO-）氧化成水（H2O）和二氧化碳（CO2）作为反应中间体。根据密度泛函理论模拟,1-MnCo2O4的较高催化活性可归因于其优异的表面性能的综合作用(例如，FA分子的牢固附着，降低FA吸附的能源成本，和较低的CO2和H2O解吸能量)。这项工作是关于碱（KOH）改性的MnCo2O4的合成及其在黑暗中在室温下氧化去除FA的应用的第一份报告。这项研究的结果有望为DLT开发针对室内FA的有效且具有成本效益的非贵金属催化剂提供有价值的见解。
