Effects of γ–Irradiation and Ageing on Surface and Catalytic Properties of Nano–sized CuO/MgO System
Sahar A. El–Molla,1* Sahar A. Ismail,2 and Marwa M. Ibrahim3
1 Chemistry Department, Faculty of Education, Ain Shams University, Roxy, Heliopolis, Cairo 11757, Egypt,*saharelmolla@yahoo.com
2 National Center for Radiation Research and Technology, Nasr City, Cairo 11731, Egypt, p.o. box 29.
Received November 22, 2010. ]]> Accepted March 01, 2011.
Abstract
0.2 CuO/MgO system prepared by impregnation method was calcined at 350 and 450 °C. The effects of γ–rays (0.2–1.6 MGy) on its structure, surface and catalytic properties were investigated by using XRD, N2–adsorption at –196 °C and catalytic conversion of iso–propanol at 150–275 °C using a flow technique. The results revealed that the investigated solids consisted of nano–sized MgO as a major phase besides CuO and trace amount of Cu2O. γ–Irradiation of the solids investigated exerted measurable changes on their surface and catalytic properties dependent on the calcination temperature and dose of irradiation. The catalysts investigated acted as active dehydrogenation solids. The five years–ageing of different solids showed limited changes of their surface and catalytic properties indicating a good catalytic stability of the irradiated prepared solids.
Keywords: Nano–materials, metal oxides, γ–irradiation, catalytic activity, catalytic stability.
Resumen
El sistema de 0.2 Cu/MgO preparado por el método de impregnación fue calcinado a 350 y 450 °C. El efecto de la irradiación γ (0.2–1.6 MGy) en su estructura, superficie y propiedades catalíticas, fue investigado utilizando XRD; la adsorción de N2 a –196 °C y la conversión catalítica de isopropanol a 150–275 °C fue determinada utilizando una técnica de flujo. Los resultados revelaron que los sólidos investigados consistieron de nano MgO como fase predominante, además de CuO y trazas de Cu2O. La radiación γ de los sólidos investigados ejercen cambios medibles en su superficie y las propiedades catalíticas dependen de la temperatura de calcinación y de la dosis de radiación.El catalizador estudiado actúa como un sólido de deshi–drogenación activo. Los 5 años de envejecimiento de los diferentes sólidos mostraron cambios muy limitados en su superficie y en las propiedades catalíticas indicando una buena estabilidad catalítica de los sólidos preparados e irradiados.
Palabras clave: Nano–materiales, óxidos metálicos, irradiación gamma, actividad catalítica, estabilidad catalítica.
]]> DESCARGAR ARTÍCULO EN FORMATO PDF
References
1. Diez, V. K.; Apesteguia, C. R.; Di Cosimo, J. I. Catal. Today 2000, 63, 53–62. [ Links ]
2. Xu, M.; Gines, M. G. L.; Hilmaen, A.–M.; Stephens, B. L.; Iglesia, E. J. Catal. 1997, 171, 130–147. [ Links ]
3. Zhang, G.; Hattori, H.; Tanabe, K. Appl. Catal. 1988, 36, 189–197. [ Links ]
4. Dicosimo, J. I.; Diez, V. K.; Apesteguia, C. R. Appl. Catal. 1996, 137, 149–166. [ Links ]
5. Kurokawa, H.; Kato, T.; Kuwabara, T.; Ueda, W.; Morikawa, Y.; Moro–Oka, Y.; Ikawa, T. J. Catal. 1990, 126, 208–218. [ Links ]
6. El–Molla, S. A. Appl. Catal. A. 2005, 280, 189–197. [ Links ]
7. El–Molla, S. A. Appl. Catal. A. 2006, 298, 103–108. [ Links ]
8. Mucka, V.; Mižik, P. Radiat. Phys. Chem. 1991, 38, 291–294. [ Links ]
9. Andreev, A.; Kafedjiiski, V.; Halachev, T.; Kunev, B.; Kaltchev, M. Appl. Catal. 1991, 78, 199–211. [ Links ]
10. Spalaris, C. N ; Bupp, L. P. ; Gilbert, E. C. J. Phys. Chem. 1957, 61, 350–354. [ Links ]
11. El–Nabarawy, Th.; EL–Shobaky, G. A.; Dessouki, A. M. Thermochim. Acta. 1987, 111, 249–255. [ Links ]
12. Mucka, V.; Podlaha, J.; Silber, R. Radiat. Phys. Chem. 2000, 59, 467–475. [ Links ]
13. El–Shobaky, H. G.; Ahmed, A. S.; Radwan, N. R. N. Colloids Surf. A. 2006, 274, 138–144. [ Links ]
14. El–Shobaky, G. A.; Doheim, M. M.; Ghozza, A. M.; El–Boohy, H. A. Mater. Lett. 2002, 57, 525–531. [ Links ]
15. El–Boohy, H. A.; Doheim, M.M.; EL–Shobaky, G. A. Afinidad 2002, 59, 497–502. [ Links ]
16. Doheim, M. M.; El–Boohy, H. A.; EL–Shobaky, G. A. Adsorp. Sci. Technol. 2001, 19, 635–643. [ Links ]
17. Doheim, M. M.; Ahmed, A. S.; El–Boohy, H. A.; EL–Shobaky, G. A. J. Radioanal. Nucl. Chem. 2002, 254, 583–588. [ Links ]
18. Cordi, E. M.; O'Neill, P. J.; Falconer, J. L. Appl. Catal. B 1997, 14, 23–36. [ Links ]
19. Aboukaïs, A.; Bechara, R. ; Aïssi, C. F.; Bonnelle, J. P.; Ouqour, A.; Loukah, M.; Coudurier, G.; Vedrine, J. C. J. Chem. Soc. Faraday Trans. 1993, 89, 2545–2549. [ Links ]
20. Ahmed, A. I. Bull. Soc. Chem. Fr. 1990, 2, 179–183. [ Links ]
21. Rekoske, J. E.; Barteau, M. A. J. Catal. 1997,165, 57–72. [ Links ]
22. Dicosimo, J. I.; Torres, G.; Apesteguia, C. R. J. Catal. 2002, 208, 114–123. [ Links ]
23. Chen, Y. Z.; Hwang, CM.; Liaw, C. W. Appl. Catal. A 1998, 169, 207–214. [ Links ]
24. Gandía, L. M.; Montes, M. Appl. Catal. A. 1993, 101, L1–L6. [ Links ]
25. Nicol, W.; Du Toit, E. L. Chem. Eng. Process. 2004, 43, 1539–1545. [ Links ]
26. El–Shobaky, G. A.; El–Molla, S. A.; Hammed, M. N.; Amine, N. H.; Sultan, S. N. 11th International Electronic Conference on Synthetic Organic Chemistry ECSOC–11, 1–30 November 2007; http://www.mdpi.org/ecsoc–11.htm. [ Links ]
27. El–Shobaky, G. A.; El–Molla, S. A.; Ismail, S. A. J. Radioanal. Nucl. Chem. 2004, 260, 627–636. [ Links ]
28. El–Shobaky, G. A.; Mokhtar, M.; Salem, A. M. Mater. Res. Bull. 2005, 40, 891–902. [ Links ]
29. El–Shobaky, G. A.; Fagal, G. A.; Petro, N.; Dessouki, A. M. Radial Phys. Chem. 1987, 29, 39–43. [ Links ]
30. Youssef, A.; El–Hakam, S. A.; El–Shobaky, G. A. Radiat. Phys. Chem. 1992, 40, 575–578. [ Links ]
31. El–Shobaky, G. A.; Ahmed, A.S.; Mokhtar, M. 1997, 219, 89–94. [ Links ]
32. Mucka, V. Radiat. Phys. Chem. 1996, 48, 309–313. [ Links ]
33. Mucka, V. Radiat. Phys. Chem. 1987, 30, 293–301. [ Links ]
34. Wolkenstein, Th. Adv. Catal. 1960, 12, 189–264. [ Links ]
35. Torres, G.; Apesteguia, C. R.; Dicosimo, J. I. Appl. Catal. A. 2007, 317, 161–170. [ Links ]
36. Cullity, B. D. Elements of X–Ray Diffraction, 2nd Ed, Addison–Wesley, MA, USA, 1978. [ Links ]
]]>