Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water
Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water
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DOI：
10.1007/s13399-020-01184-0
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发表时间：
2021-02
影响因子：
4
通讯作者：
I. Tews;Aidan Garcia;Michael Ayiania;S. H. Mood;Kalidas Mainali;Jean-Sabin McEwen;M. García-Pérez
中科院分区：
文献类型：
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作者：
I. Tews;Aidan Garcia;Michael Ayiania;S. H. Mood;Kalidas Mainali;Jean-Sabin McEwen;M. García-Pérez
催化湿式氧化（CWO）处理富含有机物的废水是一种很有前途的生物质转化废水处理技术。CWO反应通过在氧化剂存在下产生的自由基物质的形成而发生，其作用于流出物中的有机污染物。尽管该反应是众所周知的，但在新型生物能源工艺中缺乏经济实惠的催化剂来在较低的温度和压力下进行该过程。本研究评估了掺氮煤焦作为一种选择的催化效果。苯酚水溶液被用作模型废水。在中等温度（190至260 °C）、IMPa的氧分压和15、30和45分钟的反应时间下在不锈钢和玻璃衬里的管式反应器中进行处理。产物的高压液相色谱（HPLC）分析定量苯酚和副产物浓度，用于计算反应活化能。通过X射线光电子能谱（XPS），透射电子显微镜（TEM），扫描电子显微镜（SEM），以深入了解其结构和表面组成的焦炭催化剂进行了研究。结果表明，氮掺杂的煤焦催化剂可使苯酚的氧化反应活化能从82.2 kJ/mol（未催化）降低到40.4 kJ/mol（催化），从而促进苯酚的氧化。使用密度泛函理论（DFT）从第一原理进行分析以确定在氧存在下哪个N官能团对自由基形成具有最显著的影响。在所研究的所有N官能团中，联吡啶官能团显示出最有希望促进羟基自由基形成的特性。图形摘要
Catalytic wet oxidation (CWO) of aqueous effluents rich in organic compounds is a very promising technology for the treatment of liquid wastes from biomass conversion processes. CWO reactions occur through the formation of free radical species, produced in the presence of an oxidant, which act on organic contaminates in the effluent. Although the reaction is well known, there exists a lack of affordable catalysts to conduct this process at the lower temperatures and pressures in novel bioenergy processes. This study assessed the catalytic effect of nitrogen-doped chars as such an option. Phenol in aqueous solution was used as a model waste effluent. Treatment was conducted at moderate temperatures (190 to 260 °C), oxygen partial pressure of 1 MPa, and reaction times of 15, 30, and 45 min in stainless steel and glass-lined tube reactors. High pressure liquid chromatography (HPLC) analyses of the products quantified phenol and by-product concentrations used in the calculation of reaction activation energy. The char catalyst was studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) in order to gain insight into its structure and surface composition. The results indicate that nitrogen-doped char catalysts accelerate the oxidation of phenol by decreasing its reaction activation energy from 82.2 kJ/mol (non-catalyzed) to 40.4 kJ/mol (catalyzed). An analysis from first principles using density functional theory (DFT) was conducted to ascertain which N functional group has the most significant impact on free radical formation in the presence of oxygen. Among all the N functional groups studied, the dipyridinic functional groups showed the most promising characteristics to facilitate the formation of hydroxyl free radicals.Graphical abstract