采用微孔扩散-共沉淀法制备了不同Ce/Zr摩尔比的Ce_(1-x)Zr_xO_2(x=0,0.2,0.4,0.5)固溶体,并以此为载体用超声波助分散等体积浸渍法制备了Co_(0.2)/Ce_(1-x)Zr_xO_2催化剂,考察了催化剂中Ce/Zr比对其催化柴油车尾气碳烟颗粒物燃烧反应性能的影响.结果表明,在催化剂与碳烟颗粒松散接触条件下,Co_(0.2)/Ce_(1-x)Zr_xO_2催化剂催化碳烟颗粒物燃烧的活性非常高.其中Co_(0.2)/Ce_(0.8)Zr_(0.2)O_2催化剂活性最高,T_(10),T_(50),T_(90)S~m_(Co2)分别为316℃,385℃,413℃和99.9%.这与目前文献报道的松散接触条件下活性最高的担载Pt催化剂相近.应用X射线衍射、透射电镜、扫描电镜、紫外-可见漫反射和傅里叶变换红外光谱技术对Ce_(1-x)Zr_xO_2固溶体及Co_(0.2)/Ce_(1-x)Zr_xO_2催化剂进行了表征.结果表明,Ce_(1-x)Zr_xO_2固溶体由纳米级小颗粒组成(平均粒径在10nm左右).适量的Ce/Zr比有利于改善立方尖晶石型Co_3O_4在Ce1-xZr_xO_2固溶体表面的分散,从而提高催化剂活性.程序升温还原结果表明,Co_(0.2)/Ce_(0.8)Zr_(0.2)O_2催化剂具有最优的低温还原特性,与它具有最高的催化活性相一致.
A series of Ce_(1-x)Zr_xO_2 (x = 0, 0.2, 0.4, 0.5) solid solutions were prepared by the micropore-diffused coprecipitation method with ammonia solution as precipitation agent. Co_(0.2)/Ce_(1-x)Zr_xO_2 catalysts were prepared by the ultrasound-assisted incipient-wetness impregnation method. The effect of Ce/Zr molar ratio on the catalyst activity for soot combustion was investigated. The Co_(0.2)/Ce_(1-x)Zr_xO_2 catalysts gave very high activity for soot combustion under loose contact conditions between soot and catalyst, and the catalytic activity of Co_(0.2)/Ce_(0.8)Zr_(0.2)O_2 catalyst was the highest, whose T_(10),T_(50), T_(90), and S~m_(co2) were 316℃, 385℃, 413℃, and 99.9%, respectively Compared with when there was no catalyst, T_(10),T_(50), and T_(90) decreased by 136, 197, and 226℃, respectively, and S~cm increased by 45.9%. This catalytic activity for soot combustion was as good as that of supported Pt catalysts, which was the best catalyst system so far reported for soot combustion under loose contact conditions. All the samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that nanometer Ce_(1-x)Zr_xO_2 solid solution supports can be prepared by the micropore-diffused coprecipitation method. The average particle size of Ce_(1-x)Zr_xO_2 solid solutions was about 10 nm. Doping Zr affected the dispersion of Co over Ce_(1-x)Zr_xO_2 solid solutions, The right Ce/Zr molarratio was beneficial in enhancing the catalyst activity. Temperature-programmed reduction with hydrogen showed that the Co_(0.2)/Ce_(0.8)Zr_(0.2)O_2 catalyst had the lowest reduction temperature (203 and 298℃), which was in good agreement with its best catalytic activity.
参考文献
| [1] | 贺泓,翁端,资新运.柴油车尾气排放污染控制技术综述[J].环境科学,2007(06):1169-1177. |
| [2] | 赵震,张桂臻,刘坚,梁鹏,许洁,段爱军,姜桂元,徐春明.柴油机尾气净化催化剂的最新研究进展[J].催化学报,2008(03):303-312. |
| [3] | Sayle DC.;Maicaneanu SA.;Watson GW. .Atomistic models for CeO2(111), (110), and (100) nanoparticles, supported on yttrium-stabilized zirconia[J].Journal of the American Chemical Society,2002(38):11429-11439. |
| [4] | 毛小波,陈耀强,赵明,袁书华,李俊强,龚茂初.铈锆比对低贵金属Pt+Rh/Ce0.3+xZr0.6-xY0.1O1.95+Al2O3三效催化剂性能的影响[J].化学学报,2007(04):300-304. |
| [5] | Hori C E;Permana H;Simong Ng K Y;Brenner A More K Rahmoeller K M Belton D .[J].Applied Catalysis B:Environmental,1998,16:105. |
| [6] | Liu G;Rodriguez J A;Hrbek J;Dvorak J Peden C H F .[J].Journal of Physical Chemistry B,2001,105:7762. |
| [7] | Atribak I;Bueno-Lopez A;Garcia-Garcia A .Combined removal of diesel soot particulates and NOx over CeO2-ZrO2 mixed oxides[J].Journal of Catalysis,2008(1):123-132. |
| [8] | Pisarello M L;Milt V;Peraita M A;Querini C A Miro E E .[J].Catalysis Today,2002,75:465. |
| [9] | Mu Z;Li J J;Duan M H;Hag Z P Qiao S Z .[J].Catalysis Communications,2008,9:1874. |
| [10] | Liu J;Zhao Zh;Wang J Q;Xu C M Duan A J Jiang G Y Yang Q .[J].Applied Catalysis B:Environmental,2008,84:185. |
| [11] | 何洪;戴洪兴;貲学红 .[P].CN 100374194,2007. |
| [12] | Uchisawa J O;Obuehi A;Zhao Z;Kushiyama S .[J].Applied Catalysis B:Environmental,1998,18:183. |
| [13] | Letichevsky S;Tellez CA;de Avillez RR;da Silva MIP;Fraga MA;Appel LG .Obtaining CeO2-ZrO2 mixed oxides by coprecipitation: role of preparation conditions[J].Applied Catalysis, B. Environmental: An International Journal Devoted to Catalytic Science and Its Applications,2005(3/4):203-210. |
| [14] | Si R;Zhang Y W;Li S J;Lin B X Yan C H .[J].Journal of Physical Chemistry B,2004,108:12481. |
| [15] | Natile, MM;Glisenti, A .CoOx/CeO2 nanocomposite powders: Synthesis, characterization, and reactivity[J].Chemistry of Materials,2005(13):3403-3414. |
| [16] | Bumajdad A;Zaki MI;Eastoe J;Pasupulety L .Microemulsion-based synthesis of CeO2 powders with high surface area and high-temperature stabilities[J].Langmuir: The ACS Journal of Surfaces and Colloids,2004(25):11223-11233. |
| [17] | Singh R N;Pandey J P;Singh N K;Lal B Chartier P Koenig J F .[J].Electrochimica Acta,2000,45:1911. |
| [18] | Binet C;Badri A;Lavalley J C .[J].Journal of Physical Chemistry,1994,98:6392. |
| [19] | Tang CW;Kuo CC;Kuo MC;Wang CB;Chien SH .Influence of pretreatment conditions on low-temperature carbon monoxide oxidation over CeO2/Co3O4 catalysts[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,2006(1):37-43. |
| [20] | Ji Y G;Zhao Z;Duan A J;Jiang G Y Liu J .[J].Journal of Physical Chemistry C,2009,113:7186. |
| [21] | Lug J Y;Meng M;Li X;Li X G Zha Y Q Hu T D Xie Y N Zhang J .[J].Journal of Catalysis,2008,254:310. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%