论文部分内容阅读
采用共沉淀的方法合成了一系列不同CeO_2和ZrO_2质量比的催化剂(wCeO_2-(1-w)ZrO_2)并用于汽油车颗粒物的催化燃烧。采用程序控制以10°C?min~(-1)的升温速率,从室温升到850°C氧化测试催化剂的燃烧活性。同时,对催化剂进行了X射线衍射(XRD)、拉曼(Raman)光谱、氮气-吸脱附比表面(N2-BET)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)分析、储氧能力(OSC)、氢气-程序升温还原(H2-TPR)表征。经过800°C焙烧后,70%CeO_2-30%ZrO_2样品表现出最好的活性性能,其Tm(活性测试燃烧反应中燃烧产物浓度达到最大峰值铈所对应的燃烧温度)从空白样品的719°C降低到625°C。同时,70%Ce O2-30%Zr O2样品也表现出优异的热稳定性能。催化燃烧性能与催化剂的结构、表面组成特性以及氧化还原性能有关。XRD和拉曼光谱表明富铈样品具有典型的立方相结构,富锆样品具有四方相结构。XPS表明不同催化剂的Ce中Ce~(3+)的摩尔比例及表面氧与晶格氧的比例存在明显差异,其导致催化性能不同。同时,70%CeO_2-30%ZrO_2样品具有最大的储氧能力及最优异的还原性能。此外,焙烧温度的升高,70%Ce O2-30%ZrO_2样品在结构、表面组成和氧化还原能力并没有出现明显的下降和破坏,表明70%Ce O2-30%ZrO_2样品具有优良的热稳定性能。
A series of catalysts (wCeO 2 - (1-w) ZrO 2) with different CeO 2 and ZrO 2 mass ratios were synthesized by coprecipitation and used for the catalytic combustion of gasoline particulate matter. Using programmed control, the combustion activity of the catalyst was tested by oxidation at room temperature to 850 ° C at a heating rate of 10 ° C? Min ~ (-1). At the same time, the catalysts were characterized by XRD, Raman, N2-BET, X-ray photoelectron spectroscopy (XPS) Oxygen storage capacity (OSC), hydrogen-temperature programmed reduction (H2-TPR) characterization. After calcination at 800 ° C, the 70% CeO_2-30% ZrO_2 sample showed the best activity with a Tm (combustion temperature at which the combustion product reached the maximum peak value of cerium for the activity test combustion) from 719 ° C down to 625 ° C. At the same time, the 70% Ce O2-30% Zr O2 sample also showed excellent thermal stability. Catalytic combustion properties and the catalyst structure, surface composition and redox properties related. XRD and Raman spectra show that the cerium-rich samples have a typical cubic phase structure and the zirconium-rich samples have a tetragonal phase structure. XPS shows that the Ce ~ (3 +) molar ratio of Ce in different catalysts and the ratio of surface oxygen to lattice oxygen have significant differences, leading to different catalytic properties. At the same time, the 70% CeO_2-30% ZrO_2 sample has the largest oxygen storage capacity and the most excellent reduction performance. In addition, no significant decrease and destruction of the structure, surface composition and redox ability of the sample of 70% Ce O2-30% ZrO 2 were observed with the increase of calcination temperature, indicating that the sample of 70% Ce O2-30% ZrO 2 has excellent thermal stability performance.