Influence of calcination temperature on the catalytic activity of Mn/TiO2 for NO oxidation
-
摘要: 以浸渍在二氧化钛上的锰基催化剂为对象,研究了制备过程中煅烧温度对锰基催化剂催化NO氧化活性的影响。结果表明,较低的煅烧温度有利于提高Mn/TiO2催化剂对于NO氧化的催化效率。利用X射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、X射线光电子能谱(XPS)、H2程序升温还原(H2-TPR)和O2程序升温脱附(O2-TPD)等表征手段研究了煅烧温度影响Mn/TiO2催化剂催化活性的作用机理。结果表明,在NO氧化过程中发挥主要作用的是Mn2O3,较低的煅烧温度有利于提高Mn2O3在锰氧化物中所占的比例,同时增加锰氧化物在载体表面的分散度,从而改善催化剂活性;当煅烧温度超过500 ℃时,催化剂会发生烧结,载体TiO2的晶形开始由锐钛型向金红石型转变,Mn2O3也从非晶相向晶相转变。H2-TPR和O2-TPD测试结果表明,低温煅烧有利于提高催化剂的还原性能和表面化学吸附态O2-的脱附性能,良好的还原性能和脱附性能的相互作用使催化剂表面的氧有较好的移动能力,从而促进催化剂的活性。Abstract: The influence of calcination temperature on the catalytic activity of Mn-based catalysts impregnated on TiO2 for the oxidation of NO was studied. The results showed that, relatively low calcination temperature was beneficial to promote the catalytic activity of Mn/TiO2 catalysts. The catalysts were characterized by various techniques to study the influence mechanism of calcination temperature, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR) and O2 temperature programmed desorption (O2-TPD). It could be concluded that Mn2O3 played a dominant role in the process of NO oxidation, and the relatively lower calcination temperature could enhance the percentage of Mn2O3 in MnOx, as well as promote the dispersion of MnOx on TiO2, thus raising the catalytic activity of Mn/TiO2. When the calcination temperature was higher than 500 ℃, the agglomeration began to appear, and the crystalline phase of TiO2 was transformed from anatase to rutile, Mn2O3 was, as well, transformed from amorphous phase to crystalline phase. The test results of H2-TPR and O2-TPD showed that relatively lower calcination temperature was beneficial to the reduction ability of Mn/TiO2 catalysts and the desorption of chemisorbed O2- on catalysts surface, the interaction of the two factors resulted in good mobility of chemisorbed O2- on catalysts surface, which was good for the activity of catalysts.
-
Key words:
- calcination temperature /
- NO oxidation /
- catalyst /
- preparation /
- pollution control
-
张虎, 佟会玲, 王晋元, 陈昌和. 用KMnO4 调质钙基吸收剂从燃煤烟气同时脱硫脱硝[J]. 化工学报, 2007, 58(7): 1810-1815. (ZHANG Hu, TONG Hui-ling, WANG Jin-yuan, CHEN Chang-he. Simultaneous removal of SO2 and NO by using calcium absorbent with KMnO4 as additive[J]. Journal of Chemical Industry and Engineering(China), 2007, 58(7): 1810-1815.) SKALSKA K, MILLER J S, LEDAKOWICZ S. Trends in NOx abatement: A review[J]. Sci Total Environ, 2010, 408(19): 3976-3989. RUGGERI M P, NOVA I, TRONCON E. Experimental study of the NO oxidation to NO2 over metal promoted zeolites aimed at the identification of the standard SCR rate determining step[J]. Top Catal, 2013, 56(1/8): 109-113. WANG Z, ZHANG X, ZHOU Z, CHEN C, ZHOU J, CEN K. Effect of additive agents on the simultaneous absorption of NO2 and SO2 in the calcium sulfite slurry[J]. Energy Fuels, 2012, 26(9): 5583-5589. 赵迎宪, 危凤, 张艳辉, 虞影. NO在 Pt/γ-Al2O3 上催化氧化反应机理和动力学[J]. 化工学报, 2008, 59(5): 1156-1164. (ZHAO Ying-xian, WEI Feng, ZHANG Yan-hui, YU Ying. Mechanism and kinetics of NO oxidation over Pt/SymbolgA@-Al2O3 catalyst[J]. Journal of Chemical Industry and Engineering(China), 2008, 59(5): 1156-1164.) LI L, SHEN Q, CHENG J, HAO Z. Catalytic oxidation of NO over TiO2 supported platinum clusters I. Preparation, characterization and catalytic properties[J]. Appl Catal B: Environ, 2010, 93(3): 259-266. YUNG M M, HOLMGREEN E M, OZKAN U S. Cobalt-based catalysts supported on titania and zirconia for the oxidation of nitric oxide to nitrogen dioxide[J]. J Catal, 2007, 247(2): 356-367. ZHANG J, ZHANG S, CAI W, ZHONG Q. The characterization of CrCe-doped on TiO2-pillared clay nanocomposites for NO oxidation and the promotion effect of CeOx[J]. Appl Surf Sci, 2013, 268: 535-540. LI K, TANG X, YI H. Mechanism of catalytic oxidation of NO over Mn-Co-Ce-Ox catalysts with the aid of nonthermal plasma at low temperature[J]. Ind Eng Chem Res, 2011, 50(19): 11023-11028. QI G, YANG R T. Performance and kinetics study for low-temperature SCR of NO with NH3 over MnOx-CeO2 catalyst[J]. J Catal, 2003, 217(2): 434-441. QI G, YANG R T. Low-temperature selective catalytic reduction of NO with NH3 over iron and manganese oxides supported on titania[J]. Appl Catal B: Environ, 2003, 44(3): 217-225. WU Z, TANG N, XIAO L, LIU Y, WANG H. MnOx/TiO2 composite nanoxides synthesized by deposition-precipitation method as a superior catalyst for NO oxidation[J]. J Colloid Interface Sci, 2010, 352(1): 143-148. XU W, ZHAO J, WANG H, ZHU T, LI P, JING P. Catalytic oxidation activity of NO on TiO2-supported Mn-Co composite oxide catalysts[J]. Acta Phys-Chim Sin, 2013, 29(2): 385-390. TANG X, HAO J, YI H, LL J. Low-temperature SCR of NO with NH3 over AC/C supported manganese-based monolithic catalysts[J]. Catal Today, 2007, 126(3): 406-411. PINNA F. Supported metal catalysts preparation[J]. Catal Today, 1998, 41(1): 129-137. PARK E, CHIN S, JEONG J, JURNG J. Low-temperature NO oxidation over Mn/TiO2 nanocomposite synthesized by chemical vapor condensation: Effects of Mn precursor on the surface Mn species[J]. Micropor Mesopor Mater, 2012, 163: 96-101. ETTIREDDY P R, ETTIREDDY N, MAMEDOV S, BOOLCHAND P, SMIRNIOTIS P G. Surface characterization studies of TiO2 supported manganese oxide catalysts for low temperature SCR of NO with NH3[J]. Appl Catal B: Environ, 2007, 76(1): 123-134. STOBBE E R, DE BOER B A, GEUS J W. The reduction and oxidation behaviour of manganese oxides[J]. Catal Today, 1999, 47(1): 161-167. MORALES M R, BARBERO B P, CADUS L E. Total oxidation of ethanol and propane over Mn-Cu mixed oxide catalysts[J]. Appl Catal B: Environ, 2006, 67(3): 229-236. DELIMARIS D, IOANNIDES T. VOC oxidation over MnOx-CeO2 catalysts prepared by a combustion method[J]. Appl Catal B: Environ, 2008, 84(1): 303-312. TANG X, HAO J, XU W, LI J. Low temperature selective catalytic reduction of NOx with NH3 over amorphous MnOx catalysts prepared by three methods[J]. Catal Commun, 2007, 8(3): 329-334. ATRIBAK I, BUENO-LóPEZ A, GARCíA-GARCíA A, NAVARRO P, FRíAS D, MONTES M. Catalytic activity for soot combustion of birnessite and cryptomelane[J]. Appl Catal B: Environ, 2010, 93(3): 267-273. CIMINO A, INDOVINA V. Catalytic activity of Mn3+ and Mn4+ ions dispersed in MgO for CO oxidation[J]. J Catal, 1974, 33(3): 493-496. KAPTEIJN F, SMGOREDJO L, ANDREML A. Activity and selectivity of pure manganese oxides in the selective catalytic reduction of nitric oxide with ammonia[J]. Appl Catal B: Environ, 1994, 3(2): 173-189. TRAWCZYNSKI J, BIELAK B, MISTA W. Oxidation of ethanol over supported manganese catalysts—Effect of the carrier[J]. Appl Catal B: Environ, 2005, 55(4): 277-285. LEITH I R, HOWDEN M G. Temperature-programmed reduction of mixed iron—manganese oxide catalysts in hydrogen and carbon monoxide[J]. Appl Catal, 1988, 37: 75-92. SULTANA A, SASAKI M, HAMADA H. Influence of support on the activity of Mn supported catalysts for SCR of NO with ammonia[J]. Catal Today, 2012, 185(1): 284-289.
点击查看大图
计量
- 文章访问数: 1094
- HTML全文浏览量: 16
- PDF下载量: 677
- 被引次数: 0