Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8材料的制备及在三效催化剂中的应用

采用共沉淀法制备了Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8(0≤x≤0.4)材料, 并对所制备的材料进行了X射线衍射(XRD)和X射线光电子能谱(XPS)的表征, 测定了材料的比表面积(BET法)和储氧量(OSC), 同时采用氢气程序升温还原(H2-TPR)和氨气程序升温脱附(NH3-TPD)研究了材料的还原性能和表面酸性. 研究结果表明, Ce/Ti摩尔比大于1∶2的材料能形成立方萤石结构的固溶体, Ce/Ti摩尔比为1时, 材料表面Ce4+/Ce3+摩尔比达到最大; 随着Ce/Ti摩尔比的增大, 材料的储氧能力先增大后减小, 而TPR还原峰温则是先减小后增大, 当Ce/Ti摩尔比为1时, 材料的储氧量达到最大, 为660 μmol/g; 还原峰峰温最低, 为616 ℃. 以制备的材料为载体制备了一系列Pt/Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8三效催化剂, 并对催化剂进行了活性评价. 活性测试结果表明, 以Ce/Ti比为1的载体材料制成的催化剂对C3H8, CO和NO的起燃温度分别为236, 147和228 ℃, 表现出了优异的温度特性.

Preparation of Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8 and Its Application in Three-way Catalyst

Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8(0≤x≤0.4) mixed oxides were prepared by co-precipitation method and characterized by means of X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), nitrogen adsorption(BET), oxygen storage capacity(OSC), H2-temperature programmed reduction(H2-TPR) and NH3-temperature programmed desorption(NH3-TPD). The results of XRD revealed that there was only one single cubic phase in Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8 system when x value increased from 0.2 to 0.4. The results of XPS showed that the ratio of superficial Ce4+/Ce3+ is maximal when x is 0.2. With the increase of Ce/Ti ratio, OSC is increased to a maximum value, and then gradually decreased. When x value is 0.2, the OSC reaches to 660 μmol/g, and the reduction temperature of Ce4+ is the lowest according to the H2-TPR test(616 ℃). In this paper, a series of Pt/Ce0.1+xTi0.5-xAl0.2Y0.1La0.1O1.8 three-way catalysts were prepared and the catalytic activities of catalysts were investigated. The results revealed that Pt/Ce0.3Ti0.3Al0.2Y0.1La0.1O1.8 exhibits excellent low-temperature catalytic activity. The light-off temperature of C3H8, CO and NO over Pt/Ce0.3Ti0.3Al0.2Y0.1La0.1O1.8 is 236, 147 and 228 ℃, respectively.