Sn、Ti掺杂改性γ-Fe_2O_3催化剂结构及NH_3-SCR脱硝活性研究  

Structural property of γ- Fe_2O_3 catalysts doped with Sn and Ti and their activity in the selective catalytic reduction of NO_x

作　　者：王栋[1,2] 吴惊坤 牛胜利[1,2] 路春美[1,2] 徐丽婷[1,2] 于贺伟 李婧[3] 

机构地区：[1]山东大学能源与动力工程学院,山东济南250061 [2]山东大学燃煤污染物减排国家工程实验室,山东济南250061 [3]山东大学化学与化工学院,山东济南250100

出　　处：《燃料化学学报》2015年第7期876-883,共8页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(51276101);高等学校博士学科点专项科研基金(20120131110022);山东大学基本科研业务费专项资金(2015JC024)

摘　　要：采用共沉淀-微波热解法,制备一系列Sn、Ti掺杂改性γ-Fe2O3催化剂样品（γ-Fe0.95Ti0.05Oz、γ-Fe0.95Sn0.05Oz、γ-Fe0.95Sn0.025Ti0.025Oz）,研究Sn、Ti掺杂对γ-Fe2O3催化剂SCR脱硝活性的影响,借助XRD、N2吸附-脱附、EDS及SEM等手段对催化剂晶相、孔结构、表面元素及微观形貌等进行表征分析。结果表明,Sn、Ti掺杂后以无定形态高度分散于γ-Fe2O3晶格中,与Fe形成固溶体;单一助剂Ti掺杂制得的γ-Fe0.95Ti0.05Oz最高脱硝效率达98.3%,且在250~400℃脱硝效率保持90%以上;Ti掺杂可以细化γ-Fe2O3晶粒,优化2~100 nm孔径孔隙结构,抑制α-Fe2O3的生成,促使γ-Fe2O3形成细致、均匀、独立的球状颗粒,对SCR反应有利;Sn掺杂则使催化剂出现严重烧结现象,导致2~6 nm孔径孔结构贫乏,对SCR脱硝反应不利;在Sn、Ti协同作用下,催化剂表面氧铁原子物质的量比由1.83降至1.33,表面晶格氧显著下降,一定程度上限制了SCR反应速率的提高。A series of γ-Fe2O3 catalysts doped with Sn and Ti （γ-Fe0.95Ti0.05Oz, γ-Fe0.95Sn0.05Oz, and y-Fe0.95 Sn0.025Ti0.025 Oz） were prepared by the microwave assisted co-precipitation method. The crystal phase, pore structure, surface element distribution and microscopic morphology of the doped T-Fe2O3 catalysts were characterized by X-ray diffraction （XRD）, N2 sorption, energy dispersive spectrometer （EDS） and scanning electron microscope （SEM）; the influence of Sn and Ti doping on their activity in the selective catalytic reduction （SCR） of NOx was investigated. The results indicated that Sn and Ti are highly dispersed as amorphous species in crystal lattice of y-Fe2O3, forming sosoloid with Fe. Through doping with Ti, the γ-Fe0.95 Ti0.05Oz catalyst exhibits a high de-NOx efficiency of above 90% at 250 -400 ℃, with a maximum of 98.3% ; the addition of Ti is effective to reduce the crystallization degree of γ-Fe2 O3, improve the pore structure of 2 - 100 nm, and suppress the formation of α-Fe2O3 phase, which are of benefits to get tiny and uniform discrete γ-Fe2O3 particles with high activity in SCR. However, Sn as an additive may aggravate the sintering and derogate pore structure of 2 - 6 nm for the y-Feo.95 Sno.05 Oz catalyst, which is detrimental to SCR. The incorporation of both Sn and Ti leads to a decrease of the surface O/Fe atomic ratio from 1.83 to 1.33 ; the dramatic decrease of surface lattice oxygen content due to the synergistic effect between Sn and Ti may restrain the SCR activity of y-Fe0.95Sn0.95sn0.025Oz.

关 键 词：选择性催化还原 脱硝 催化剂 Γ-FE2O3 助剂掺杂 

分 类 号：X511[环境科学与工程—环境工程]