CHEMICAL REACTIONS AT NANOMETAL PARTICLES
The concept of nanochemistry and the reactions involved are discussed. The work is focused on nanoparticles obtained from colloidal dispersions. The colloidal particles by transmission electron microscopy of low and high resolution were analyzed. The high resolution electron miscroscopy (HRTEM) allo...
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| Lenguaje: | English |
| Publicado: |
Sociedad Chilena de Química
2005
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| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072005000300014 |
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| Sumario: | The concept of nanochemistry and the reactions involved are discussed. The work is focused on nanoparticles obtained from colloidal dispersions. The colloidal particles by transmission electron microscopy of low and high resolution were analyzed. The high resolution electron miscroscopy (HRTEM) allow us to classify the nanostructure of the metal particles in some polyhedral models: cubooctahedron, truncated octahedron, tetracai decahedron and icosahedron. Some HRTEM of Pd-2 propanol and Ge-2-propanol are analyzed. The Pd atoms exhibit a high crystalline nanoparticles, cubooctahedral arrangement in the [001] orientation. On the other hand , the Ge atoms are ordered in a pseudohexagonal arrangement. The spacing in the last system are typical of a diamond cubic Ge structure. The structure of nanometals and also some relevant properties of nanoclusters are discussed. Some heterogeneous catalysis applications of supported metal clusters are discussed. Selective hydrogenation of a, b-unsaturated aldehydes are based on Pd, Rh, Ru, Os, Ir, Ni, Co and Pd.. In particular the crotonaldehyde hydrogenation in the presence of Pd/SiO2, Pd/Al2O3, PdSn/SiO2 and PdSn/Al2O3 was measured. The influence of the organic fragments incorporated on the surface of the particles in the systems mentioned above was studied. Finally, some remarks of the advantage of this technique in order to obtain nanoclusters are summarized |
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