中文摘要：

利用菱铁矿的热分解特性,在空气中不同温度下（400、500、600、700、800℃）煅烧天然菱铁矿制备具有纳米尺寸形貌特征的α-Fe_2O_3,作为NH_3选择性催化还原（NH_3-SCR）脱硝的催化剂.采用X射线衍射（XRD）、程序升温脱附（NH_3-TPD）、X射线光电子能谱（XPS）、紫外-可见漫反射吸收光谱（UV-Vis DRS）等手段对催化剂结构进行表征,并利用气固相催化反应系统对催化剂的NH_3-SCR脱硝活性和N_2选择性进行评价,同时考察其抗水抗硫及稳定性.结果表明,天然菱铁矿于空气中500℃煅烧相变为α-Fe_2O_3,具有最低的晶体尺寸（约10 nm）、最高的比表面积（39.68 m~2·g~（-1））和最优的脱硝活性;500℃煅烧菱铁矿制备的催化剂在250~400℃温度窗口内脱硝效率达到100%,并能保持较高的N_2选择性,这主归因于其具有的纳米多孔结构特性和较大的比表面积,以及表面丰富的酸性位点和吸附态氧.当同时存在5%H_2O和0.04%SO_2时,α-Fe_2O_3在250~400℃区间的脱硝效率高于88%,且在300℃下持续反应360 min,脱硝效率维持在75%以上,表明500℃煅烧菱铁矿制备的催化剂具有良好的抗水抗硫和稳定性.

英文摘要：

Nano-α-Fe_2O_3 was prepared by annealing siderite in air atmosphere at different temperatures（ 400,500,600,700,800 ℃） and used as catalysts for selective catalytic reduction（ SCR） of NO by ammonia. The catalytic performance of nano-α-Fe_2O_3 was evaluated in a laboratory-scale catalytic system and the effect of SO_2 and H_2O on the catalytic reduction activity was also investigated. The catalysts were characterized by X-ray diffraction（ XRD）,NH_3 temperature programmed desorption（ NH_3-TPD）,X-ray photoelectron spectroscopy（ XPS）,UV Vis diffuse reflectance spectroscopy（ UV Vis-DRS）,etc. The results showed that natural siderite was transformed into α-Fe_2O_3 after annealing at 500 ℃ in air atmosphere. The newly formedα-Fe_2O_3 at 500 ℃ had the lowest crystal size（ about 10 nm） and highest specific surface area（ 39.68 m~2·g~（-1）） compared with those of α-Fe_2O_3 prepared at other temperatures. Meanwhile,the α-Fe_2O_3 formed at 500 ℃ exhibited a high N_2 selectivity and de-NO_xperformance（ 100%） at middle-low temperature（ 250 ~ 400 ℃）. The nano-porous microstructure,large surface area,plenty acidity sites,and adsorbed oxygen on the surface of the catalyst were responsible for the excellent performance. Besides,the conversion of NO was higher than 88% at 250 ~ 400 ℃ and was maintained above 75% at 300℃ for 360 min in the presence of 5% H_2O and 0.04% SO_2. This indicated that this kind of nano-α-Fe_2O_3 had a good resistance to H2 O and SO_2 at theexperimental conditions.