1、金催化剂上的一氧化碳氧化反应,报告人：宁剑波,Seminar II,导 师：徐 杰 研究员,主要内容,背景 金催化剂上一氧化碳氧化反应的影响因素 金催化一氧化碳氧化在生产或生活中的应用 结论及其展望,高的催化活性!,Fig. 3. CO conversion over various catalysts as a function of temperature.(1) Au/a-Fe2O3 (Au/Fe = 1/19, coprecipitation, 400 ), (2) 0.5 wt% Pd/ -Al2O3 (impregnation, 300 ), (3) Au fine powder,
2、 (4) Co3O4 (carbonate,400 ), (5) NiO (hydrate, 200 ), (6) a-Fe2O3 (hydrate, 400 ), (7)5 wt% Au/a-Fe2O3 (impregnation, 200 ), and (8) 5 wt% Au/g-Al2O3(impregnation, 200 ),5%-Au/Fe2O3,0.5 wt% Pd/ -Al2O3,Co3O4,M. Haruta, N. Yamada, T. Kobayashi, S. Iijima, J. Catal. 1989, 115(2):301-308.,背景,近年金催化剂的研究,O
3、nset of Catalytic Activity of Gold Clusters on Titania with the Appearance of Nonmetallic Properties M. Valden, X. Lai, D. W. Goodman Science , 1998, 281, 1647-1650 引用651次,Low-Temperature Oxidation of CO over Gold Supported on TiO2, -Fe2O3, and Co3O4 Haruta M., Tsubota S., Kobayashi T., Kageyama H.,
4、 Genet M. J. and Delmon B. Journal of catalyst, 1993, 144, 175-192 引用462次,为什么有这么大魅力？,背景,一氧化碳低温氧化,空气净化器,CO 气体传感器,封闭式- 循环CO2 激光器,CO 防毒面具,军事,环保,生活,工业,背景,催化剂？,金的d 轨道电子是完全充满的, 并且第一电离能很大(9.22 eV ) , 很难失去电子, 因此金的表面与表面分子之间的相互作用力很弱。事实上, 在单晶金的表面, 连极具反应活性的分子, 如氢、氧等, 都不易吸附; 只有在 150 K 的低温下, CO 才能可逆吸附, 在室温下, 需很高的
5、分压才能达到吸附的平衡; 氧的解离吸附只能在946 K 以上进行(氧以原子形式存在时, CO 氧化反应才能发生); 金的熔点(1336 K)很低,要制得像铂(2042 K)、钯(1823 K)那样高分散的负载催化剂是相当困难的。,背景,化学惰性难于高分散,Au2O3 是不稳定的(Hf=+19.3 kJ/mol) 金的电负性大于所有其他的金属,只比硫和碘元素略微正一些； Au+/Au0 的标准电极电势为+1.691 V,它对电子的亲和能力实际上比氧元素还要大；,金催化剂上一氧化碳氧化反应的影响因素,粒子大小影响； 反应温度的影响； 水和氢气的促进作用； 载体及其它影响因素。,Percentage
6、 of surface atoms on perfect octahedra in corner (), edge (),and face () positions, as a function of the number of atoms along each side. Also shown are the corresponding dispersions () and sizes ().,1.粒子大小影响,影响因素,M. Haruta, Catalysis Today, 1997, 36 (1): 153-166,1.粒子大小影响,影响因素,An STM image (bottom l
7、eft) and schematic (upper left) of Au bilayer clusters on TiO2(1 1 0) whose population are dominant (lower right) for a Au/TiO2 catalyst most active for CO oxidation (upper right). The activity (at 350 K) is expressed as turnover frequency (TOF) in units of CO2 molecules produced per Au site per sec
8、ond.,T.V. Choudhary, D.W. Goodman, Applied Catalysis A: General, 2005, 291 (1/2) 3236,M. Valden, X. Lai, D. W. Goodman, Science, 1998, 281(5383):1647-1650,1.粒子大小影响,影响因素,(A) The activity for CO oxidation at 350 K as a function of the Au cluster size supported on TiO2(110)-(11) assuming total dispersi
9、on of the Au. The CO:O2 mixture was 1:5 at a total pressure of 40 Torr. Activity is expressed as (product molecules) (total Au atoms)-1s-1. (B) Cluster band gap measured by STS as a function of the Au cluster size supported on TiO2(110)-(131). The band gaps were obtained while the corresponding topo
10、graphic scan was acquired on various Au coverages ranging from 0.2 to 4.0 ML. () Two-dimensional (2D) clusters; () 3D clusters, two atom layers in height; () 3D clusters with three atom layers or greater in height. (C) Relative population of the Au clusters (two atom layers in height) that exhibited
11、 a band gap of 0.2 to 0.6 V as measured by STS from Au/TiO2(110).,M. Valden, X. Lai, D. W. Goodman, Science, 1998, 281(5383):1647-1650,1.粒子大小影响,A metal-to-nonmetal transition occurs as the cluster size is decreased below 3.5 by 1.0 nm2 (3.5 nm in diameter and 1.0 nm in height).,影响因素,(A) The activity
12、 for CO oxidation at 350 K as a function of the Au cluster size supported on TiO2(110)-(11) assuming total dispersion of the Au. The CO:O2 mixture was 1:5 at a total pressure of 40 Torr. Activity is expressed as (product molecules) (total Au atoms)-1s-1. (B) Cluster band gap measured by STS as a fun
13、ction of the Au cluster size supported on TiO2(110)-(131). The band gaps were obtained while the corresponding topographic scan was acquired on various Au coverages ranging from 0.2 to 4.0 ML. () Two-dimensional (2D) clusters; () 3D clusters, two atom layers in height; () 3D clusters with three atom
14、 layers or greater in height. (C) Relative population of the Au clusters (two atom layers in height) that exhibited a band gap of 0.2 to 0.6 V as measured by STS from Au/TiO2(110).,M. Valden, X. Lai, D. W. Goodman, Science, 1998, 281(5383):1647-1650,1.粒子大小影响,The structure sensitivity of CO oxidation
15、 on Au/TiO2 originates from quantum size effects,影响因素,1.粒子大小影响,C. Lemire, R.Meyer, S. Shaikhutdinov, H. J. Freund, Angew. Chem. Int. Ed. 2004,42(1):118-121,影响因素,The exceptional activity of gold nano-particles for the low temperature CO oxidation arise from the presence of highly uncoordinated atoms.
16、,1.粒子大小影响,影响因素,2.反应温度的影响,M. Haruta, M. Dat, Applied Catalysis A: General, 2001, 222(1/2) : 427437,影响因素,M. Haruta, M. Dat, Applied Catalysis A: General, 2001, 222(1/2) : 427437,Below 200K,Above 300K,影响因素,2.反应温度的影响,3.水的促进作用,M. Dat, M. Okumura,S. Tsubota, and M. HarutaAngew. Chem. Int. Ed. 2004, 43, 21
17、29 2132,影响因素,M. Dat, M. Okumura,S. Tsubota, and M. HarutaAngew. Chem. Int. Ed. 2004, 43, 2129 2132,H.H. Kung, M. C. Kung and C. K. Costello , Journal of Catalysis 2003, 216 (1/2) 425432,3.水的促进作用,影响因素,3.氢气的促进作用,影响因素,C. Rossignol, S. Arrii, F. Morfin, L.Piccolo, V. Caps and J. L. Rousset, Journal of C
18、atalysis, 2005, 230 (2):476483,3.氢气的促进作用,影响因素,4.其它影响因素,载体：氧的活化。可还原载体如 TiO2， Fe2O3上活性高。 制备方法：金-载体间的相互作用,粒径。浸渍法，共沉淀法，学蒸汽沉积法，有机金配合物固载法，无定形金属合金法，阳离子交换法。 预处理条件：灼烧增加金属载体相互作用。,影响因素,低温下，金催化剂上CO氧化具有高的 催化活性；具有很好的耐潮湿性能。,富氧条件下CO脱除,防毒面具 原来用hopcalite催化剂（CuMn2O4），怕水汽； Au催化剂：起活温度低，-70既有活性，0 以下CO可全部转化，不怕水。,S. J.Lee,
19、 A. Gavriilidis, Q. A. Pankhurst andA. Kyek et al., J. Catal,2001,200(2):298-308,应用,富氢条件下CO选择性脱除,在合成氨工业和燃料电池中 H2中 少量CO（12%）的脱除（100ppm） 甲烷化：CO+3H2 CH4+H2O 选择氧化CO+1/2O2 CO2 H2+1/2O2 H2O 活性顺序Au/Ru/Rh/Pt/Pd/-Al2O3 T100CO 50 100 200 400 选择性% 100 80 40 极低,应用,N. W. Cant and N. J. Ossipoff, Catalysis Today,
20、 1997 ,36( 1): 125-133,C Plog, W Maunz, T Stengel et al. EP:0650922A1, 1995.,封闭式CO2激光器,在封闭式CO2激光器中，如太空CO2激光器，随着使用可发生以下反应： CO2 CO+1/2O2+hv 用金催化剂可以使其在现场再生： CO+ 1/2O2 CO2,应用,M. Haruta, Catalysis Today, 1997, 36 (1): 153-166.,结论及其展望,CO 的低温氧化催化剂具有广泛的应用前景。负载型纳米金催化剂是用于CO 低温氧化的良好催化材料。影响金催化剂活性的主要因素有: 制备方法、粒径
21、、载体及载体金的相互作用。尽管关于金催化剂催化CO 氧化的研究开展持续了20年之久,但关于金催化剂的催化CO 氧化的活性机理和反应机理, 还需要进一步研究与探讨。,结论及其展望,Although we are well past the beginning of the discovery of golds catalytic potential, the best may be yet to come, and a golden future lies ahead.-G. C. Bond,Catalysis Today, 2002, 72 (1/2) :59.,谢谢,参考文献,M. Haru
22、ta, N. Yamada, T. Kobayashi and S. Iijima, J. Catal. 1989, 115(2):301-308. M. Haruta and M. Dat, Applied Catalysis A: General, 2001, 222(1/2) : 427437. M. Haruta, Catalysis Today, 1997, 36 (1): 153-166. T.V. Choudhary and D.W. Goodman, Applied Catalysis A: General, 2005, 291 (1/2) 3236. M. Valden, X
23、. Lai and D. W. Goodman, Science, 1998, 281(5383):1647-1650. C. Lemire, R.Meyer, S. Shaikhutdinov and H. J. Freund, Angew. Chem. Int. Ed. 2004,42(1):118-121. M. Dat, M. Okumura,S. Tsubota, and M. HarutaAngew. Chem. Int. Ed. 2004, 43, 2129 2132. H.H. Kung, M. C. Kung and C. K. Costello , Journal of C
24、atalysis 2003, 216 (1/2) 425432. C. Rossignol, S. Arrii, F. Morfin, L.Piccolo, V. Caps and J. L. Rousset, Journal of Catalysis, 2005, 230 (2):476483. S. J.Lee, A. Gavriilidis, Q. A. Pankhurst and A. Kyek et al., J. Catal,2001,200(2):298-308. N. W. Cant and N. J. Ossipoff, Catalysis Today, 1997 ,36( 1): 125-133. C Plog, W Maunz and T Stengel et al. EP:0650922A1, 1995. G. C. Bond,Catalysis Today, 2002, 72 (1/2) :59.,
