# Platinum as a Catalyst

## Design of Platinum Catalysts

Heterogeneous catalysts containing platinum and precious metals are now used in many large-scale technical processes in the chemical and petrochemical industries.

With only a few exceptions (see platinum gauzes), platinum and other precious metals used in catalysis are mainly components of two-component systems known as metal-support catalysts. In these, the noble and expensive platinum is distributed as finely as possible on the support material in order to generate a large number of catalytically active centers. For this purpose, support substances are used that have the largest possible specific (“internal”) surface area and have a suitable system of porosity. In practice, these are, for example, highly porous materials based on alumina, silica, titania or active charcoal. The platinum is distributed in the form of minute nano-crystals in the porosity system of the support material.

Fig.1
Distribution of platinum crystallites

Distribution of platinum crystallites in the porosity system of the support material

Fig.2
$Pd$/$C$ catalyst

The figure shows a TEM micrograph of a $Pd$/$C$ catalyst

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