Preparation Of Highly Dispersed Pt On Activated Carbon With Low Metal Loading

Highly dispersed Pt on activated carbon with low metal loading are know to be efficient catalytic materials in organic reaction for the production of fine chemicals. The structure of Pt/C catalyst is significantly influenced by the preparation route and/or the treatment procedure. In this dissertation, four methods were employed to prepare Pt/C catalysts. They are NaBH4-reduction. HCOOH-reduction, Ethylene glycol-reduction, and a novel chelation-reducion route originated in this dissertation. Compared with previous methods, the novel chelation-reduction can be used to prepare Pt/C catalysts with nano-sized particles.Optimizing of preparation variables showed that pH value, reduction temperature, impregnation duration and/or Tempe ration, addition sequence of the supports all have significant influence on the particle size and the morphology of as-synthesized catalysts during preparation process. It was proposed that the platinum (IV) was reduced by formaldehyde to platinum particles.TEM observation and chemisorption measurements consistently indicated that platinum particles made by chelation-reduction were highly dispersed over carbon with rather smaller particles (2~5nm).