摘要
分别采用水热法和浸渍法2种合成方法制备了Ce-MnO_(x)催化剂,应用于氨的选择性催化氧化。实验结果表明:水热法制备的Ce-MnO_(x)具有更高的催化氧化NH_(3)活性,其中,在反应温度为200℃时,Ce(5)-MnO_(x)(HY)具有98%的NH_(3)转化率及91%的N_(2)选择性。XRD、BET、Raman、XPS、SEM、H_(2)-TPR等方法对催化剂的表征结果表明,水热法合成的Ce-MnO_(x)具有更大的比表面积(94.37 m^(2)/g),其优异的催化活性归因于表面丰富的Mn^(4+)和Ce^(3+)、大量的化学吸附氧、丰富的活性位点、Mn和Ce间的相互作用等。In-situ DRIFTS分析表明,催化剂表面吸附态的NH_(3)经过脱氢作用生成—NH_(2)、—NH中间体,其中,—NH与原子氧结合生成的—HNO能被O_(2)快速氧化形成NO,NO再与—NH_(2)继续反应生成N_(2)和H_(2)O。研究可为锰基催化剂在低温氨氧化及选择性方面的研究提供重要参考。
In this paper, Ce-MnO_(x)was prepared for selective catalytic oxidation(SCO) of ammonia by hydrothermal and impregnation method respectively. The results demonstrated that Ce-MnO_(x)catalysts exhibited the best NH_(3) oxidation activity which composited by hydrothermal method. Among them, Ce(5)-MnO_(x)(HY) reached 98% of NH_(3) conversion rate and 91% of N_(2) selectivity, at reaction temperature of 200 ℃. The properties of the Ce-MnO_(x)catalysts were analyzed by XRD, BET, Raman, XPS, SEM, and H_(2)-TPR. Hydrothermally prepared Ce-MnO_(x) possessed larger surface area(94.37 m^(2)/g). At the same time, the distinguished catalytic activity of Ce-MnO_(x)was attributed to abundant Mn^(4+) and Ce^(3+), high adsorbed oxygen concentration on the surface, a large number of active sites, and interaction between Mn and Ce. The results of in-situ DRIFTS showed that the —NH_(2) and —NH intermediates could be generated by adsorbed NH_(3) dehydrogenation. Consequently, —NH and atomic oxygen combined to form —HNO, which could be quickly oxidized to NO by O_(2). Finally, N_(2) and H_(2)O were formed during the following reaction of NO with —NH_(2). This dissertation has significant reference value for the study of manganese-based catalysts in low-temperature ammonia oxidation and selectivity.
作者
盛雨佳
陈冬
刘海波
陈天虎
束道兵
张斌
SHENG Yujia;CHEN Dong;LIU Haibo;CHEN Tianhu;SHU Daobing;ZHANG Bin(Key Laboratory of Nano-minerals and Pollution Control of Anhui Higher Education Institutes,School of Resources&Environmental Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《环境工程》
CAS
CSCD
北大核心
2022年第1期60-68,共9页
Environmental Engineering
基金
国家自然科学基金项目(41672040)。
