采用分步浸渍法分别制备了LaCeZr和YCeZr组合助剂改性的介孔Al_2O_3负载的Mn基系列氧化物催化剂,用X射线衍射、氮气吸附-脱附、X射线吸收精细结构、X射线光电子能谱和程序升温还原等方法对催化剂进行了表征,探讨了催化剂中Mn物种的存在形式及其还原性能,并与样品催化CO和C_3H_8的氧化活性相关联.结果表明,样品中Mn物种主要以Mn_3O_4形式存在,该物种在不同样品中与载体的作用强弱不同,从而表现出不同的还原性能和催化活性.助剂改性有效抑制了Mn-Al之间的相互作用,提高了Mn-O键的活动度,从而提高了催化剂的氧化活性.相比于YCeZr助剂,LaCeZr助剂改性更大程度上提高了Mn物种的还原性,因而大大提高了催化剂的氧化性能.650℃焙烧的LaCeZr组合助剂改性的介孔Al_2O_3负载的Mn氧化物催化剂,在0.035%SO_2存在的条件下对CO的氧化活性并未下降,对C_3H_8的氧化活性下降幅度也较小,表现出优越的抗硫性能和氧化性能.
The manganese oxide catalysts supported on mesoporous Al_2O_3 modified by LaCeZr or YCeZr were prepared by successive im-pregnation. The structure of the catalysts was characterized by X-ray diffraction, N2 adsorption-desorption, X-ray absorption fine structure, X-ray photoelectron spectroscopy, and temperature-programmed reduction by H_2. The state of manganese species and their reducibility were investigated and correlated with the CO and C_3H_5 oxidation performance of the catalysts. The results demonstrate that the manganese species mainly exist as Mn_3O_4 crystallites, which interact with the support Al_2O_3. The different interaction strength determines the reducibility and catalytic properties of the catalysts. The promoters LaCeZr or YCeZr effectively inhibit the interaction between Mn and Al oxides, increasing the mobility of Mn-O bond and the catalytic activity of the corresponding catalysts. Compared with YCeZr, the promoter LaCeZr improves the reducibility of MnO_x to a larger extent, enhancing the activity more obviously. The catalysts modified by LaCeZr calcined at 650 ℃ ex-hibits high oxidation performance and sulfur resistance. In the presence of 0.035% SO_2 in the feed, the CO oxidation activity of the catalyst can be well maintained, and the C_3H_8 oxidation activity decreases only a little.
参考文献
| [1] | 姚金松,孟明,罗金勇,查宇清,谢亚宁,胡天斗,刘涛.高分散锰氧化物催化剂的结构、性能及载体效应[J].分子催化,2006(04):300-305. |
| [2] | 李想,孟明,姚金松,谢亚宁,胡天斗,刘涛.Mn/Ce/La/Al2O3催化剂中锰物种的精细结构研究[J].无机化学学报,2007(02):211-216. |
| [3] | Wang X Y;Kang Q;Li D .[J].Applied Catalysis B:Environmental,2009,86:166. |
| [4] | Delimaris D;Ioannides T .[J].Applied Catalysis B:Environmental,2009,84:303. |
| [5] | 唐晓龙,郝吉明,徐文国,李俊华.新型MnOx催化剂用于低温NH3选择性催化还原NOx[J].催化学报,2006(10):843-848. |
| [6] | 张晓玉,刘志敏,魏振玲,杜小春,龚茂初,陈耀强.高性能甲烷催化燃烧催化剂的制备及其在天然气催化燃烧热水器上的应用[J].催化学报,2006(09):823-826. |
| [7] | 王永军,袁书华,史忠华,赵明,龚茂初,刘忠长,陈启章,陈耀强.满足欧Ⅲ排放标准的汽油车中偶催化剂[J].催化学报,2007(02):97-99. |
| [8] | Trawczynski J;Bielak B;Mista W .Oxidation of ethanol over supported manganese catalysts-effect of the carrier[J].Applied Catalysis, B. Environmental: An International Journal Devoted to Catalytic Science and Its Applications,2005(4):277-285. |
| [9] | 孟明,张忠和,罗金勇,林培琰,伏义路.荧光XAFS表征Pt/BaAl2O4-Al2O3催化剂中的微量铂物种[J].无机化学学报,2006(02):298-302. |
| [10] | Kapteijn F;Vanlangeveld A D;Moulijn A;Andreini A Vuurman M A Turek A M Jehng J M Wachs I E .[J].Journal of Catalysis,1994,150:94. |
| [11] | (A)lvarez-Galv(a)n M C;Pawelec B;de la Pena O;Shea V A Fierro J L G Arias P L .[J].Applied Catalysis B,2004,51:83. |
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