State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
Environ Sci Technol. 2018 Oct 16;52(20):11769-11777. doi: 10.1021/acs.est.8b03732. Epub 2018 Oct 8.
CeO-WO-ZrO mixed oxides were prepared by the homogeneous precipitation method for the selective catalytic reduction of NOx with NH (NH-SCR). The effects of hydrothermal aging on the catalytic performances of CeO-WO-ZrO were investigated. The results showed that CeO-WO-ZrO catalyst exhibited excellent NH-SCR activity for removal of NOx and hydrothermal stability. After hydrothermal aging at 850 °C for 16 h, the optimum CeO-WO-ZrO catalyst could still realize 80% NOx conversion at 300-500 °C even under a high gas hourly space velocity of 250 000 h. The structural properties, redox ability, surface species, and acidity of fresh and hydrothermally aged CeO-WO-ZrO catalysts were characterized by N-physisorption, XRD, Raman, H-TPR, XPS, NH-TPD, and in situ DRIFTS. The characterization results showed that decreases of 89% of the surface area and 71% of the NH storage capacity as well as new phase formation occurred for the CeO-WO-ZrO sample after hydrothermal aging at 850 °C for 16 h. The activity of hydrothermally aged CeO-WO-ZrO was mainly attributed to the retention of redox-acid sites and their interaction due to the formation of Ce-Zr solid solutions and CeWO.
CeO-WO-ZrO 混合氧化物通过均相沉淀法制备，用于 NH（NH-SCR）选择性催化还原 NOx。考察了水热老化对 CeO-WO-ZrO 催化性能的影响。结果表明，CeO-WO-ZrO 催化剂在去除 NOx 和水热稳定性方面表现出优异的 NH-SCR 活性。在 850°C 下水热处理 16 h 后，即使在高气体空速为 250000 h 的情况下，最佳的 CeO-WO-ZrO 催化剂仍能在 300-500°C 下实现 80%的 NOx 转化率。通过 N 物理吸附、XRD、拉曼、H-TPR、XPS、NH-TPD 和原位 DRIFTS 对新鲜和水热老化的 CeO-WO-ZrO 催化剂的结构特性、氧化还原能力、表面物种和酸度进行了表征。表征结果表明，在 850°C 下水热处理 16 h 后，CeO-WO-ZrO 样品的比表面积和 NH 储存能力分别下降了 89%和 71%，同时形成了新相。水热老化的 CeO-WO-ZrO 的活性主要归因于由于形成了 Ce-Zr 固溶体和 CeWO，氧化还原-酸位及其相互作用得以保留。
