Preparation of platinum-iridium nanoparticles on titania nanotubes by MOCVD and their catalytic evaluation

• Published in: Journal of alloys and compounds Vol. 483; no. 1; pp. 406 - 409
• Main Authors: Colindres, S. Capula, García, J.R. Vargas, Antonio, J.A. Toledo, Chavez, C. Angeles
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier B.V 26.08.2009; Elsevier
• Subjects: Catalysis; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Nanostructured materials; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vapor deposition; Nanostructured materials; Vapor deposition; Catalysis; Binary compound; Particle size; High resolution; Support; Nanoparticle; Nanotube; Hydrogenation; Physisorption; Sodium hydroxide; Platinum; Raman spectrometry; Platinoid; BET method; Catalytic reaction; Transition element compounds; Transition metal; Nanostructure; Nitrogen; X ray diffraction; Chemical vapor deposition; Heterogeneous catalysis; Transmission electron microscopy; Dehydrogenation; Preparation; Iridium; Titanium oxide; Catalyst; Hydrothermal condition
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2008.08.097

Pt based catalysts are commonly used in several industrial processes involving hydrogenation and dehydrogenation reactions. New deposition methods as well as support materials are being investigated to generate new catalysts with superior catalytic activity. In this work, platinum-iridium (Pt-Ir) nanoparticles of about 5 nm in size were supported on titania (TiO 2) nanotubes by metal organic chemical vapor deposition (MOCVD). The TiO 2 nanotubes were prepared by an alkali hydrothermal method using sodium hydroxide solution at 100 °C, during 64.8 ks. Pt-Ir nanoparticles were obtained by controlling the MOCVD conditions at 400 °C and 66.6 kPa. Textural properties and particle size were investigated by nitrogen physisorption (BET method), X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. Catalytic activity was measured in cyclohexene disproportion as the test molecule for hydrogenation/dehydrogenation reactions. The TiO 2 nanotubes exhibit a considerable high surface area of about 425,000 m 2/kg, however, after calcination at 400 °C their nanotubular morphology was partially transformed. In spite of this change, the 5 nm Pt-Ir nanoparticles supported on TiO 2 nanotubes were more active in the cyclohexene disproportion reaction than conventional Pt-Ir/alumina catalysts in the whole range of temperatures investigated (50–250 °C). Hydrogenation reactions (high selectivity to cyclohexane) predominate at temperatures below 150 °C.