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14. Netherlands' Catalysis and Chemistry Conference4. Netherlands' Catalysis and Chemistry Conference, Netherlands, pp.62, (Summary Text)
Preparation of Multiwall Carbon Nanotube Supported Cu and Pd Nanoparticles Using Supercritical CO2 Deposition Method
Fatma Ulusal, Burcu Darendeli, Bilgehan Güzel
Chemistry Departmant, University of Cukurova, 01330 Adana, TURKEY
Metal nanoparticles supported on high surface area carbon substrates are used extensively as catalysts for a wide variety of reactions. Among these catalysts, multiwall carbon nanotube (MW-CNT) supported Pd and Cu catalysts are commonly used for hydrogenation and oxydation reactions in organic synthesis. MW-CNT supported metal nanoparticles are prepared by a variety of methods including microemulsion method, impregnation, sonochemical method, modified polyol reduction and deposition-precipitation method. The catalytic properties of such materials depend strongly on the preparation method. The supercritical fluid (SCF) deposition technique has recently been receiving increased attention for the preparation of carbon supported catalysts. This process involves the dissolution of a metallic precursor (MP) in a supercritical fluid and the exposure of the carbon support to the solution. After adsorption of the precursor onto the support, the metallic precursor is converted to its metal form by chemical or thermal reduction. This technique has been used to prepare nanoparticles of a wide variety of metals including Pt, Pd, Ru and Rh supported on various types of carbon substrates as well as other substrates [1].
(a) (b) (c)
Fig 1. (a) Bis(dmg)Pd(II), (b) TEM image of Pd/MWCNT, (c) XRD pattern of Pd/MWCNT
In this work the scCO2 deposition method is used for the preparation of solid supported heterogeneous catalysts using by vic-dioxime derivative new precursors such as bis(3- perfluoro vic dioximato)Cu(II) and Pd(II). The complexes were prepared with 3-perfluoro vic dioxime and copper(II) acetate mono hydrate and palladium (II) chloride. The ligands and their complexes were characterized by elemental analyses such as FT-IR, 1H, 13C NMR and elemental analysis. In order to prepare Cu or Pt/MWCNT catalysts, the carbon nanotube support was exposed to a solution of desired Cu or Pd oximes dissolved in scCO2 and the precursors adsorbed on the surface of the support. Subsequently, the precursors were reduced to their metal form by chemical reduction in a supercritical mixture of H2 and CO2. The prepared catalysts were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). From the TEM images it was seen that Pd particles were not homogeneously distributed on the MWCNT support with numerous large particles with sizes ranging from 8 to 85 nm. In contrast to Pd nanoparticles, Cu particles were found to be homogeneously distributed with small particle sizes between 7 and 22 nm on MWCNT.
[1] Erkey C., Preparation of metallic supported nanoparticles and films using supercritical fluid deposition, J. of Supercritical Fluids 47 (2009) 517–522.
E-mail: bilgehan@cu.edu.tr