Castillo N., García Serrano L.A., Flores Sandoval C.A., Pérez R.
UNAM, MX
Keywords: Pt-Pd catalysts, TEM, X-RD, XEDS
Nanoparticles, specially metallic nanoparticles finely dispersed onto high surface area supports, play an important role in heterogeneous catalysis because the performance of a supported metal catalyst can be related to design, which is most crucial for the development of novel catalytic processes. It requires some understanding of the mechanism of the catalytic reaction, and knowledge of the crucial properties which determine the activity, selectivity and lifetime of the catalyst. Studies of the interrelationship between structural and chemical properties of solid materials and their catalytic properties. These studies are frequently carried out using specially prepared model catalysts which are amenable to analysis with modern surface analytical methods providing structural and chemical information on molecular scale, as TEM attach with X-EDS. Various techniques and concepts of solid state and surface chemistry are applied for modifying and synthesizing catalyst materials with the required structural and chemical properties. In this work, we preparated Pt-Pd bi metallic catalysts by impregnation with chloroplatinic acid and palladium chloride supported on TiO2. The structural and physic characterization of these samples were carried out by BET Surface Area, X-Rays Diffraction (X-RD), Transmission Electron Microscopy (TEM), attach with X-Ray and Energy Dispersive Spectroscopy (XEDS). Our interest in Pt-Pd catalysts in skeletal reactions of hydrocarbons has been initiated by both practical and theoretical reasons. Both catalysts, in supported or unsupported forms, are active in skeletal isomerization, C5-cyclization, aromatization, and, to a lesser extent, hydrogenolysis. Of the two metal blacks, Pd was more selective toward C6 product formation from various hexane isomers than Pt[6]. It is well known that supported metal catalyst can exhibit drastically different performances depending on conditions of preparation and treatment. Catalytic properties of Pt-Pd/TiO2 for Metilciclopentene conversion (skeletal isomerization and hydrogen transfer) have been studied. It has been shown that catalytic activity are increased on samples, but at the same time products of the hydrogen transfer reaction seem to be increased too, lowering the selectivity of the reaction: isomerization always predominates. Keywords Pt-Pd catalysts, TEM, X-RD, XEDS. Figure 1. The high resolution electron (microscopy) HRTEM images of Pt-Pd nanocrystals oriented along [110]. Figure 2. TEM brigh field shows TiO2 around particles 200 nm and Pt-Pd and small metallic (Pt-Pd) particles around 20 nm. REFERENCES 1. A. Baladin, Advances in Catalysis, vol. X, pag. 96, Academic Press, Inc., New York, 1958. 2. O. Beeck, Disc. Faraday Soc., 8, 118 (1950). 3. M. Boundart, J. Am. Chem. Soc., 72, 1040 (1950). 4. S. Gao and L.D. Schmidt. J. Catal. 115, 356-364. (1989). 5. Zbigniew Karpinski and Tomase Koscielki Atalic, Catal. 63, 313-323, 1980. 6. Paal, Z. and Tetenyi, P. Appl. Catal. 1, 9 (1981). 7 .Koscielki T., Karpinski Z. and Z. Paal, J. Catal. 77, 539-549 (1982). 8.Yamamoto H, Uchida H Catal. Today 45: (1-4) 147-151 OCT 19 1998 9. PassoFabio B. s, Aranda Donato A.G. and Schmal. J. Martín Catal. 178, 478-488 (1998). 10. Falconer John L. and Magreini-Bair Kimberley A. J. Catal. 179, 171-178 (1998). 11. Kennedy C. James III and Datye K. Abhaya. J. Catal 179, 375-389 (1998). 12. Almusaiteer Khalid and Chuang, Steven S. C. J. Catal 180, 161-170 (1998). 13. G. Prelazzi, M. Cerboni and G. Leofanti. J. Catal. 181, 73-79 (1999). 14. R. Burch and J.A. Sullivan. J. Catal. 182, 489-496 (1999). 15. Neuman Solange de Resende, Jean Guillaume Eon, and Martib Schmal. J. Catal. 183, 6-13 (1999) 16. Ajit Dandekar and M. Albert Vannice. J. Catal 183, 344-354 (1999) 17. Khalid Almusaiteer and Steven S. C. Chuang, J. Catal 184, 189-201 (1999). 18. Yamamoto H, Uchida H. Catal. Today 45: (1-4) 147-151 OCT 19 1998 19. PassoFabio B. s, Aranda Donato A.G. and Schmal. J. Martín. J. Catal. 178, 478-488 (1998). 20. Falconer John L. and Magreini-Bair Kimberley A. J. Catal. 179, 171-178 (1998). 21. Kennedy C. James III and Datye K. Abhaya. J. Catal 179, 375-389 (1998). 22. Almusaiteer Khalid and Chuang, Steven S. C. J. Catal 180, 161-170 (1998). 23. G. Prelazzi, M. Cerboni and G. Leofanti. J. Catal. 181, 73-79 (1999). 24. R. Burch and J.A. Sullivan. J. Catal. 182, 489-496 (1999). 25. Neuman Solange de Resende, Jean Guillaume Eon, and Martib Schmal. J. Catal. 183, 6-13 (1999) 26. Ajit Dandekar and M. Albert Vannice. J. Catal 183, 344-354 (1999) 27. Khalid Almusaiteer and Steven S. C. Chuang, J. Catal 184, 189-201 (1999).
Journal: TechConnect Briefs
Volume: 3, Technical Proceedings of the 2003 Nanotechnology Conference and Trade Show, Volume 3
Published: February 23, 2003
Pages: 199 - 202
Industry sector: Advanced Materials & Manufacturing
Topic: Nanoparticle Synthesis & Applications
ISBN: 0-9728422-2-5