Highly dispersed V_2O_5/TiO_2 modified with transition metals(Cu,Fe,Mn,Co) as efficient catalysts for the selective reduction of NO with NH_3  

过渡金属(Cu,Fe,Mn,Co)改性高分散V_2O_5/TiO_2作为高效NH_3-SCR脱硝催化剂（英文）

作　　者：赵欣[1] 黄垒[1] 李红蕊[1] 扈航[1] 韩瑾[1] 施利毅[2] 张登松[1] 

机构地区：[1]上海大学纳米科学与技术研究中心,上海200444 [2]上海大学化学系,上海200444

出　　处：《Chinese Journal of Catalysis》2015年第11期1886-1899,共14页催化学报（英文）

基　　金：supported by the National Natural Science Foundation of China (21303099);the National Basic Research Program of China(973 Program,2014CB660803);the Shanghai Municipal Education Commission(14ZZ097, B.3704713001);the Research Fund for Innovation Program of Shanghai University (K.10040713003)~~

摘　　要：Different transition metals were used to modify V2O5-based catalysts （M-V, M = Cu, Fe, Mn, Co） on TiO2 via impregnation, for the selective reduction of NO with NH3. The introduced metals induced high dispersion in the vanadium species and the formation of vanadates on the TiO2 support, and increased the amount of surface acid sites and the strength of these acids. The strong acid sites might be responsible for the high N2 selectivity at higher temperatures. Among these catalysts, Cu-V/TiO2 showed the highest activity and N2 selectivity at 225-375 ~C. The results of X-ray photo- electron spectroscopy, NH3-temperature-programmed desorption, and in-situ diffuse reflectance infrared Fourier transform spectroscopy suggested that the improved performance was probably due to more active surface oxygen species and increased strong surface acid sites. The outstanding activity, stability, and SO2/H2O durability of Cu-V/TiO2 make it a candidate to be a NOx removal catalyst for stationary flue gas.选择性催化还原(SCR)是目前固定源及移动源中控制NOx排放最为有效的技术手段之一.工业上应用最广泛的商业SCR催化剂是钒基催化剂.钒基催化剂经钨(钼)改性后具有较好的活性、稳定性和抗水抗硫性能,但在应用过程中仍存在N2选择性较低、活性温度窗口(300–400℃)较窄及高温下V2O5极易流失等不足,且钨(钼)的价格十分昂贵.因此,用廉价组分提高钒基催化剂的催化性能在实际工业应用中仍具有重要意义.研究发现,很多非贵金属(如Cu,Fe,Mn,Co,Ce,Zr,Nb,Sn,La等)都可以代替钨(钼)用来提高钒基催化剂的选择性、活性温度窗口和(热)稳定性能等.引入的金属通常以氧化物或钒酸盐形式存在,并与活性组分钒物种有很强的相互作用,从而提高钒物种的氧化还原性能及分散度,同时增大表面酸性位数量,抑制锐钛矿向金红石相转变.近年来很多研究发现,经金属改性的钒基催化剂以钒酸盐形式存在时可有效提高催化剂活性和N2选择性,尤其可显著提高催化剂的(热)稳定性.本文采用浸渍法以廉价易得、储量丰富的过渡金属改性钒基催化剂,得到高度分散的M-V/TiO2(M=Cu,Fe,Mn,Co)脱硝催化剂.结果发现,Cu-V/TiO2和Fe-V/TiO2催化剂表现出较好的催化活性和N2选择性以及优异的稳定性和抗H2O/SO2性能,其中Cu-V/TiO2的工作温度窗口扩展到225–375℃.X射线衍射、拉曼光谱和EDX-mapping表征结果证明,钒物种及引入的金属高度分散在TiO2载体表面,并生成了钒酸盐.氢气程序升温还原结果表明,钒酸盐的形成导致钒物种的还原峰向低温区移动,有利于催化剂氧化还原性能的提升.X射线光电子能谱结果表明,Cu-V/TiO2催化剂表面具有更多的活性氧物种(Oα),且具有较强的电子间相互作用,是SCR活性提高的关键原因之一.NH3程序升温脱附和原位红外光谱实验结果表明,金属的引入可以提高酸量和酸强度;Cu-V/TiO2催化剂表面�

关 键 词：deNOx Selective catalytic reduction Vanadate Transition metal 

分 类 号：O643.36[理学—物理化学] X701[理学—化学]