Mn_xCo_(2.5-x)Al_(0.5)O_4尖晶石型三元复合氧化物催化分解N_2O(英文)

用溶胶凝胶法制备了一组Mn_xCo_(2.5-x)Al_(0.5)O_4尖晶石型三元复合氧化物,用于有氧气氛下的N_2O催化分解反应.用N_2物理吸附、X射线衍射(XRD)、扫描电镜(SEM)、H_2程序升温还原(H_2-TPR)、O_2程序升温脱附(O_2-TPD)、X射线光电子能谱(XPS)等技术对催化剂进行了结构表征,考察了催化剂组成、母液pH、K负载量等制备参数对其催化活性的影响.结果表明:K的加入弱化了催化剂表面的金属-氧化学键,有利于表面氧物种的脱除,改性催化剂有较高的催化活性和抗水性,其中母液pH=2、K/(Mn+Co)比为0.02的K/Mn_(0.2)Co_(2.3)Al_(0. 5)O_4催化剂活性较高,该催化剂在有氧、有氧有水气氛400℃连续反应50 h,N_2O转化率分别达98.5%和76.5%.

Catalytic Decomposition of N2O over MnxCo2.5-xAl0.5O4 Ternary Spinel Oxides

A series of MnxCo2.5-xAl0.5O4 ternary spinel oxides were prepared by sol-gel method for N2O catalytic decomposition in the presence of oxygen. These catalysts were characterized by means of techniques such as nitrogen physisorption, X-ray diffraction(XRD), scanning electron microscopy(SEM), temperature-programmed reduction of hydrogen(H2-TPR), temperature-programmed desorption of oxygen(O2-TPD), and X-ray photoelectron spectroscopy(XPS). The effect of preparation parameters such as compositions, pH values of mother liquid, and potassium loadings on their catalytic activity in N2O decomposition has been investigated. The results show that K-modified catalysts exhibit better reducibility and higher resistance towards water due to the weakness of surface metal-oxygen bonds in contrast to un-modified catalyst, the K/Mn0.2Co2.3Al0.5O4 prepared using mother liquid of pH=2 and K/(Mn Co) molar ratio of 0.02 is most active. In addition, 98.5% and 76.5% conversions of N2O over 0.02K/Mn0.2Co2.3Al0.5O4 could be maintained after 50h at 400C in atmosphere of oxygen and oxygen-steam together, respectively.