1910

A comparative study of silver-cobalt and silver-manganese composite oxide catalysts:Preparation,characterization and testing for the oxidation of CO

Gümüş-kobalt ve gümüş mangan kompozit oksit katalizörleri birlikte çöktürme yöntemi ile farklı metal/metal oksit molar oranlarında ve farklı çöktürme hızlarında hazırlandılar. Katalizörlerin X-Ray difraksiyonu, BET yüzey alan ve TGA çalışmaları ile karakteristik özellikleri belirlendi. CO oksidasyonu için katalitik aktivite çalışmaları bir mikroreaktörde gerçekleştirildi ve reaksiyon kuru ve ıslak atmosferde CO+hava ve CO+CO2+H2O gaz karışımıyla test edildi. Yavaş ekleme yöntemi ile hazırlanmış 1:1 Ag/Co katalizörü ve üstten ekleme yöntemi ile hazırlanmış l: l Ag/Mn katalizörü kuru hava koşulları altında en iyi performansı gösterdiler. Besleme gazına CO2 ve H2O eklendiği zaman katalizörlerin aktivitelerinde gözle görülür bir azalma meydana geldi. Ama ıslak atmosferde gümüş-kobalt kompozit oksit katalizörü gümüş-mangan kompozit oksit katalizöründen daha yüksek aktivite verdi.

Gümüş-kobalt ve gümüş-mangan kompozit oksit katalizörlerinin karşılaştırılmalı çalışması:Hazırlama,karakterizasyon ve CO oksidasyonu için test edilmesi

Silver-cobalt and silver-manganese composite oxides were prepared by co-precipitation method at different metal/metal oxide molar ratio and by different rates of preparation. The catalysts were characterised by X-Ray diffraction, BET and TGA. The CO oxidation studies were carried out in a micro reactor and reaction was formed under dry and wet atmospheres for a binary CO + air and CO + CO2 H2O + air gas mixtures. 1:1 Ag/Co prepared by the slow precipitation and 1:1 Ag/Mn prepared by the opposite slow precipitation gave the best performance for the dry conditions. Activity of these catalysts significantly decreased when the water vapor and CO2 was added to the feed. Silver-cobalt composite oxide catalyst shows a higher performance than the silver-manganese composite oxide catalyst for the wet atmospheres.

PDF

___

1. Gardner, S., Hoflund,G.B., Upruch, B.T., Schryer, D.R., Kielin, E.J. ve Scryer, J., "Comparison of the performance "characteristics and Pt/SnOx and Au/MnOx catalysts for the low temperature CO oxidation",Journal Of Catalysis, 129: 114-120(1991).
2. Tanielyan, H.S. ve Augustine, R.L., "Effect of catalyst pretreatment on the Oxidation of CO2 over coprecipitated gold catalysts", Applied catalysis, 85: 73-87 (1992).
3. Güldür, Ç., Gülari, E., Srivannovit, S. ve Osuwan, S., "CO oxidation by silver cobalt composite oxide",Applied Catalysis A:General, V:1S2(1): 147-163 (1999).
4. Thormahlen, P., Skoglundh, M., Fridell, E. ve Andersson, B., " Low temperature CO oxidation over platinum and cobalt oxide catalysts", Journal of Catalysis, 188: 300-310 (1999).
5. Jansson, J., " Low temperature CO oxidation over CO3O4/Al2O3", Journal of Catalysis, 194: 55-60 (2000).
6. Lopez, T., Asomoza, M. ve Gomez, R., " Novel Pt-Sn/Al2O3 sol-jel catalysis: synthesis and thermal characterization", Materials Letters, 19: 193-190(1994).
7. Akın, A.N., Kılaz, G., İşli, A.İ., Önsen, Z.İ., "Development and characterization of Pt-SnO2/$gamma$-Al2O3 catlysts", Chemical Engineering Science, 56: 881-888 (2001).
8. Venezia, A. M., Liottas, L. F., Deganello, G., Schay, Z., Horvath, D., Guczi, L., "Catalytic CO oxidation over pumice supported Pd-Ag catalysts", Applied Catalysis A: General: 211: 167-17 (2001).
9. Thormahlen, P., Fredell, E., Cruise, N., Skoglundh, M., Palmqvist, A., "The influence of CO2, C3H6, NO,H2, H2O or SO2 on the low temperature oxidation of CO on a cobalt-aluminate spinel catalyst $(Co_{1.66}Al_{1.34}O_4)$", Applied Catalysts B: Environmental, 31: 1-12 (2001).
10.Xiaoyuan, J., Cuanglie, L., Renxian, Z., Jianxin, M., Yu, C., Xiaoming, Z., "Studies of pore structure,temperature-programmed reduction performance and microstructure of CuO/CeO2 catalysts", Applied Surface Science, 173: 208-220 (2001).
11.Arias, A. M., Garcia, M. F., Juez, A. I., Hungria, A. B., Anderson, J. A., Conesa, J. C., Soria, J., "New $Pd/Ce_xZr_{1-x}O2/Al_2O_3$ three way catalyts prepared by microemulsion Part 2. In situ analysis of CO oxidation and NO reduction under stoichiometric CO+NO+O2", Applied Catalsis B. Environmental, 31: 51-60(2001).
12.Thammachart, M., Meeyoo, V., Risksamboon, T., Osuwan, S., "Catalytic activity of CeO2-ZrO2 mixed oxide catalysts prepared via sol-jel technique: CO oxidation", Catalysts Today, 68: 53-61 (2001).
13.Jansson, J., Palmqvist, A. E. C, Fridell, E., Skoglundh, M., Österlund, L., Thormahlen, P., Loger, V., "On the catalytic activity of Co3O4 in low temperature CO oxidation", Journal of Catalysis, 211: 387-397(2002).
14.Kung, H. H., Kung, M. C., Costello, C. K., "Supported Au catalysts for low temperature CO oxidation",Journal of Catalysis, 216: 425-432 (2003).