Zhang Shibo, Zhang Qingzhu, Zhao Yongchun, Yang Jianping, Xu Yang, Zhang Junying
Environment Research Institute, Shandong University Qingdao 266237 China
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology Wuhan 430074 China
RSC Adv. 2020 Jul 3;10(42):25325-25338. doi: 10.1039/d0ra04350h. eCollection 2020 Jun 29.
CeO modified commercial SCR (selective catalytic reduction) catalysts with different CeO content were prepared and researched for synergistic mercury removal from coal combustion flue gas in this study. The characterization analyses on the catalysts indicated that the introduction of CeO increased the surface area, the dispersity of the metal oxides on the TiO support and the redox behavior of the catalyst, which was beneficial to the catalytic activity. The experimental results confirmed that the CeO loading improved the catalytic efficiencies over the commercial SCR catalyst. The catalyst with a CeO content of 4% displayed the optimal performance for NO and synergistic Hg removal, of which the NO conversion and Hg removal efficiency reached 90.5% and 78.2%, respectively, at 300 °C in simulated coal-fired flue gas. The Hg removal activity, the independence of Hg removal from HCl concentration and the effects of SO, NO and NH on Hg removal efficiency all became positive over the modified catalyst compared to over the raw one, which was mainly due to the sufficient chemisorbed oxygen derived from the synergy of VO and CeO and the redox transformation between Ce and Ce on the catalyst surface. The CeO modification generated a significant enhancement on the catalytic performance and made the commercial SCR catalyst more suitable to be employed for NO and synergistic mercury removal in a coal combustion power plant.
本研究制备了具有不同CeO含量的CeO改性商用选择性催化还原（SCR）催化剂，并对其用于协同脱除煤燃烧烟气中的汞进行了研究。对催化剂的表征分析表明，CeO的引入增加了催化剂的比表面积、金属氧化物在TiO载体上的分散度以及催化剂的氧化还原性能，这有利于催化活性。实验结果证实，CeO负载量提高了商用SCR催化剂的催化效率。CeO含量为4%的催化剂在NO和协同脱汞方面表现出最佳性能，在300℃模拟燃煤烟气中，其NO转化率和汞脱除效率分别达到90.5%和78.2%。与未改性催化剂相比，改性催化剂上汞脱除活性、汞脱除对HCl浓度的独立性以及SO、NO和NH对汞脱除效率的影响均呈正向变化，这主要归因于VO和CeO协同作用产生的足够化学吸附氧以及催化剂表面Ce与Ce之间的氧化还原转变。CeO改性显著提高了催化性能，使商用SCR催化剂更适合用于燃煤电厂的NO和协同汞脱除。
