采用沉积沉淀法制备了CO低温氧化Au/α-Fe2O3催化剂,利用X射线衍射(XRD)、X射线光电子能谱(XPS)、BET比表面测定、程序升温还原( H2-TPR)等表征技术,对比了制备过程pH值的微小变化、焙烧及光线照射对催化剂结构及催化性能的影响,探明了Au/α-Fe2O3催化剂的活性物种.结果表明,110℃处理的Au/α-Fe2O3催化剂表面同时存在Au3+、Au0以及过渡态Auδ+(0＜δ＜1),它们对CO氧化的活性顺序为Au3+＞Auδ+＞Au0;pH值为8条件下制备的催化剂Au3+含量高、比表面积大,催化性能最好；高温焙烧使氧化态金还原的同时也使载体比表面积严重缩小,催化活性显著下降；紫外线照射可以引起Au3+的逐渐还原以及Au0颗粒的生长,其催化失活作用弱于高温焙烧.
Au/α-Fe2O3 catalysts for CO oxidation were prepared by chemical coprecipitation at different pH values, and the as-prepared samples were calcined or UV (λ=254 nm) irradiated, respectively. The structure was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption and desorption analysis (BET) and temperature programmed reduction (H2-TPR), and the active Au species on the catalysts was investigated. The results show that Au3+, Auδ+ (0≤δ≤1) and Au0 coexist on the surface of Au/α-Fe2O3 catalysts treated at 110℃, and their activity order is Au3+＞ Auδ+＞ Au0. The sample prepared at pH=8 shows the best catalytic performance since it has more Au3+ species and high specific surface area. High temperature calcination can cause serious deactivation due to the reduction of Au3+ and Auδ+ species, together with the decrease of the specific surface area ofα-Fe2O3. UV irradiation can also cause the reduction of oxidative Au species and the growth of Au particle.
参考文献
| [1] | Haruta M;Kobayashi T;SanoH .[J].Chemistry Letters,1987,16:405. |
| [2] | 王东辉;程代云;郝正平.纳米金催化剂及其应用[M].北京:国防工业出版社,2006:126. |
| [3] | Denkwitz, Y.;Schumacher, B.;Ku?erová, G.;Behm, R.J. .Activity, stability, and deactivation behavior of supported Au/TiO_2 catalysts in the CO oxidation and preferential CO oxidation reaction at elevated temperatures[J].Journal of Catalysis,2009(1):78-88. |
| [4] | Schubert M M;Plzak V;Garche J et al.[J].Catalysis Letters,2001,76(3-4):143. |
| [5] | ChoudharyT V;Goodman D W .[J].Top Cata,2002,21(1-3):25. |
| [6] | Daniells S T;Overweg A R;Makkee M et al.[J].Journal of Catalysis,2005,230(01):52. |
| [7] | 邹旭华,齐世学,索掌怀,安立敦,李峰.CO低温氧化Au/Al2O3催化剂的失活及稳定性[J].催化学报,2006(02):161-165. |
| [8] | Wang G Y;Lian H L;Zhang W X et al.[J].Kinetics and Catalysis,2002,43(03):433. |
| [9] | Schubert M M;Hackenberg S;Veen A C et al.[J].Journal of Catalysis,2001,197:113. |
| [10] | 秦亮生,银董红,刘建福,黎成勇.介孔Al2O3负载纳米Au催化剂用于低温催化氧化CO[J].催化学报,2005(08):714-718. |
| [11] | 吕倩,孟明,查宇清.高热稳定性纳米Au/TiO2催化剂的制备与表征[J].催化学报,2006(12):1111-1116. |
| [12] | Valden M;Lai X;Goodman D W .[J].Science,1998,281(5383):1647. |
| [13] | Boyd D;Golunski S;Heame G R .[J].Applied Catalysis A:General,2005,292:76. |
| [14] | 李常艳,沈岳年,胡瑞生,贾美林,盛世善.Au/Fe-O催化剂活性组分在CO催化氧化反应中的存在状态[J].催化学报,2006(03):259-262. |
| [15] | Hutchings G J;Hall M S;Carley A F et al.[J].Journal of Catalysis,2006,242:71. |
| [16] | Huang, J.;Dai, W.-L.;Fan, K. .Remarkable support crystal phase effect in Au/FeO_x catalyzed oxidation of 1,4-butanediol to γ-butyrolactone[J].Journal of Catalysis,2009(2):228-235. |
| [17] | Wang G Y;Li W C;Jia K M et al.[J].Applied Catalysis A:General,2009,364:42. |
| [18] | Minico S;Scire S;Crisafulli C et al.[J].Catalysis Letters,1997,47(3-4):273. |
| [19] | Daniells S T;Overweg A R;Makkee M .[J].Journal of Catalysis,2005,230:52. |
| [20] | 王东辉;董同欣;史喜成.纳米材料与技术应用进展——第四届全国纳米材料会议论文集[M].北京:冶金工业出版社,2005:162. |
| [21] | 王东辉,董同欣,史喜成,郝郑平.纳米金催化剂的存放失活[J].催化学报,2007(02):148-152. |
| [22] | Khoudiakov M;Gupta MC;Deevi S .Au/Fe2O3 nanocatalysts for CO oxidation: A comparative study of deposition-precipitation and coprecipitation techniques[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,2005(1/2):151-161. |
| [23] | Silberova B A A;Mul G;Makkee M et al.[J].Journal of Catalysis,2006,243:171. |
| [24] | Venugopal A;Scurrell M S.[J].Applied Catalysis A:General,2004:241. |
| [25] | Vicario M;Liorca J;Boaro M et al.[J].Journal of Rare Earths,2009,27(02):196. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%