Fe、Ce改性锰钛催化剂的制备及其低温脱硝性能研究
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摘要
为解决目前高温脱硝催化剂温区窄、易失活和中毒的问题,制备了Fe,Ce改性的MnO_x-TiO_2低温脱硝催化剂。0.08Fe0.05Ce/MnO_x-TiO_2催化剂脱硝效率达到90%以上的温区最宽,达到了99～374℃。XRD、BET测试表明催化剂的活性组分在TiO_2载体上的分散性提高,催化剂的比表面积增加。XPS分析结果表明催化剂表面化学吸附氧增加,Mn以MnO_2和Mn_2O_3的形式存在,Ce和Fe的加入促进了MnO_2和Mn_2O_3之间的转化,有利于脱硝反应的进行。H_2-TPR、NH_3-TPD分析结果表明催化剂表面的弱酸和中强酸含量提高,低温氧化还原能力提高。
In order to solve the problem that the high-temperature denitration catalyst has narrow temperature range and the property of easy deactivation and poisoning, MnO_x-TiO_2 catalyst doped with Fe and Ce of low temperature denitration was prepared in this paper. The temperature range of 0.08 Fe0.05 Ce/MnO_x-TiO_2 catalyst whose denitrification efficiency achieved above 90% was the widest of 99-374 ℃. XRD and BET analysis showed that the dispersibility of the active component of the catalyst on the TiO_2 carrier and the specific surface area of the catalyst increased. XPS analysis showed that the chemical adsorption oxygen on the surface increased, Mn existed in the form of MnO_2 and Mn_2O_3, and the addition of Ce and Fe promoted the conversion between MnO_2 and Mn_2O_3, which was beneficial to the denitration reaction. The results of H_2-TPR and NH_3-TPD analysis showed that the weak acid and medium-strong acid content on the catalyst surface increased, and the low-temperature redox ability improved.
In order to solve the problem that the high-temperature denitration catalyst has narrow temperature range and the property of easy deactivation and poisoning, MnO_x-TiO_2 catalyst doped with Fe and Ce of low temperature denitration was prepared in this paper. The temperature range of 0.08 Fe0.05 Ce/MnO_x-TiO_2 catalyst whose denitrification efficiency achieved above 90% was the widest of 99-374 ℃. XRD and BET analysis showed that the dispersibility of the active component of the catalyst on the TiO_2 carrier and the specific surface area of the catalyst increased. XPS analysis showed that the chemical adsorption oxygen on the surface increased, Mn existed in the form of MnO_2 and Mn_2O_3, and the addition of Ce and Fe promoted the conversion between MnO_2 and Mn_2O_3, which was beneficial to the denitration reaction. The results of H_2-TPR and NH_3-TPD analysis showed that the weak acid and medium-strong acid content on the catalyst surface increased, and the low-temperature redox ability improved.
引文
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[14] Scheffe J R,Francés A King D M,et al.Atomic layer deposition of iron(Ⅲ) oxide on zirconia nanoparticles in a fluidized bed reactor using ferrocene and oxygen[J].Thin Solid Films,2009,517(6):1874-1879.
[15] Jeon B H,Dempsey B A,Burgos W D.Kinetics and mechanisms for reactions of Fe(Ⅱ) with iron(Ⅲ) oxides[J].Environmental Science Technology,2003,37(15):3309-3315.
[16] Ettireddy P R,Ettireddy N,Mamedov S,et al.Supported manganese oxide catalysts for low temperature SCR of NO with NH3[J].Applied Catalysis B Environmental,2007,76(1-2):123-134.
[2] Lee D W,Yoo B R.Advanced metal oxide(supported)catalysts:synthesis and applications[J].Journal of Industrial and Engineering Chemistry,2014,20 (6):3947-3959.
[3] Zhao X,Huang L,Li H R,et al.Promotional effects of zirconium doped CeVO4 for the low-temperature selective catalytic reduction of NOx with NH3[J].Applied Catalysis B:Environmental,2016,183:269-281.
[4] Huang Y,Tong Z Q,Wu B,et al.Low temperature selective catalytic reduction of NO by ammonia over V2O5-CeO2/TiO2[J].Journal of Fuel Chemistry and Technology,2008,36(5):616-620.
[5] Zhang R,Zhong Q,Zhao W,et al.Promotional effect of fluorine on the selective catalytic reduction of NO with NH3 over CeO2-TiO2 catalyst at low temperature[J].Applied Surface Science,2014,289:237-244.
[6] Qi G S,Yang R T.Characterization and FTIR studios of MnOx-CeO2 catalyst for low-temperature selective catalytic reduction of NO with NH3[J].The Journal of Physical Chemistry B,2004,108:15738-15747.
[7] Leng X S,Zhang Z P,Li Y S,et al.Excellent low temperature NH3-SCR activity over MnaCe0.3TiOx(a=0.1-0.3) oxides:influence of Mn addition[J].Fuel Processing Technology,2018,181:33-43.
[8] Li W,Zhang C,Li X,et al.Ho-modified Mn-Ce/TiO2 for low-temperature SCR of NOx with NH3:evaluation and characterization[J].Chinese Journal of Catalysis,2018,39(10):1653-1663.
[9] Chen L Q,Yuan F L,Li Z B,et al.Synergistic effect between the redox property and acidity on enhancing the low temperature NH3-SCR activity for NOx removal over the Co0.2CexMn0.8-xTi10(x=0-0.40) oxides catalysts[J].Chemical Engineering Journal,2018,354:393-406.
[10] Wei Y,Fan H,Wang R.Transition metals(Co,Zr,Ti) modified iron-samarium oxide as efficient catalysts for selective catalytic reduction of NOx at low-temperature[J].Applied Surface Science,2018,459:63-73.
[11] Feng Yunsang.Effects of Co-Ce oxide on structure and properties of Mn/TiO2 low-temperature Denitration Catalysts[D].Zhenjiang:Jiangsu University of Science and Technology,2013(in Chinese).冯云桑.Co-Ce氧化物对Mn/TiO2系低温脱硝催化剂结构与性能的影响[D].镇江:江苏科技大学,2013.
[12] Paparazzo E.Some notes on XPS Ce3d spectra of cerium-bearing catalysts[J].Chemical Engineering Journal,2011,170(1):342-343.
[13] Yang S X,Zhu W P,Jiang Z P,et al.The surface properties and the activities in catalytic wet air oxidation over CeO2-TiO2 catalysts[J].Applied Surface Science,2006,252(24):8499-8505.
[14] Scheffe J R,Francés A King D M,et al.Atomic layer deposition of iron(Ⅲ) oxide on zirconia nanoparticles in a fluidized bed reactor using ferrocene and oxygen[J].Thin Solid Films,2009,517(6):1874-1879.
[15] Jeon B H,Dempsey B A,Burgos W D.Kinetics and mechanisms for reactions of Fe(Ⅱ) with iron(Ⅲ) oxides[J].Environmental Science Technology,2003,37(15):3309-3315.
[16] Ettireddy P R,Ettireddy N,Mamedov S,et al.Supported manganese oxide catalysts for low temperature SCR of NO with NH3[J].Applied Catalysis B Environmental,2007,76(1-2):123-134.