煅烧温度对磁性铁钛复合氧化物微观结构及脱硝活性的影响  

Influence of calcination temperature on the micro-structure and the NH_3-SCR activity of magnetic iron-titanium mixed oxide catalyst

作　　者：周飞[1,2] 熊志波 金晶[1] 武超[1] 陆威[1] 丁旭春[2] ZHOU Fei;XIONG Zhibo;JIN Jing;WU Chao;LU Wei;DING Xuchun(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Jiangsu Guoxin Jingjiang Power Company,Jingjiang 214500,Jiangsu,China)

机构地区：[1]上海理工大学能源与动力工程学院,上海200093 [2]江苏国信靖江发电有限公司,江苏靖江214500

出　　处：《化工进展》2018年第9期3410-3415,共6页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(51406118);上海市青年东方学者岗位计划(QD2015017)项目

摘　　要：利用共沉淀微波法构筑新型磁性铁钛复合氧化物催化剂,研究了煅烧温度对其物性结构及NH_3-SCR脱硝性能的影响,揭示了钛掺杂对磁性γ-Fe_2O_3晶体高温热转化及其脱硝性能的优化机制。结果表明:当煅烧温度由300℃升至500℃时,磁性铁氧化物的比表面积、孔容先增大后减小,且较高的煅烧温度促使其γ-Fe_2O_3晶体逐步转变为α-Fe_2O_3晶体,导致磁性铁氧化物表面Fe^(2+)和活性氧浓度增大,促使其NH_3-SCR脱硝性能降低;掺杂钛可提高磁性铁氧化物的热稳定性,抑制了高温煅烧下γ-Fe_2O_3晶体向α-Fe_2O_3晶体的不可逆转变和其孔隙结构的坍塌,增大了高温煅烧时磁性铁氧化物催化剂的比表面积和比孔容,合适的煅烧温度为400℃;该煅烧温度下,催化剂低温活性最佳,反应温度高于220℃、空速比60000h^(–1)时可获得80%以上的NO_x转化效率。A novel magnetic iron-titanium mixed oxide catalyst was prepared through the co-precipitation method under microwave irradiation.The effect of calcination temperature on its micro-structure and the NH3-SCR activity was investigated.The mechanism of the enhancements on the NH3-SCR activity and the high-temperature irreversible thermal transformation of magneticγ-Fe2O3 crystal by the addtion of titanium was also revealed.The results indicated that the BET surface area and the pore volume of the prepared magnetic iron oxide firstly increased and then decreased when the calcination temperature increased from 300℃to 500℃.Meanwhile,γ-Fe2O3 crystals irreversibly transformed intoα-Fe2O3 after being calcined at high temperature,giving rise to the increase of the concentrations of Fe^2+and active oxygen on its surface,thereby decreased the NH3-SCR activity of magnetic iron oxide catalyst.The addition of titanium oxide improved the thermal stability ofγ-Fe2O3 crystals in magnetic iron oxide.The irreversible thermal transformation ofγ-Fe2O3 crystal intoα-Fe2O3 crystal and the collapsing of microscopic pore structure of the magnetic iron oxide were also depressed when it was calcined at high temperature.Therefore,the addition of titanium oxide improved the BET surface area and the pore volume of the magnetic iron oxide.The suitable calcination temperature for the magnetic iron oxide based catalysts prepared through the microwave irradiation assisted co-precipitation method is 400℃,under which the catalyst showed the best low-temperature catalytic activity.When the reaction temperature was higher than 220℃,the NOx conversion was more than 80%under the gas space velocity of 60000 h^–1.

关 键 词：污染 选择催化还原 催化剂 共沉淀 煅烧温度 微观结构 微波辐射 

分 类 号：TQ3[化学工程]