Catalytic Nano-activity Points To a New Application for Platinum - New Technology

Platinum nanoparticles possess an unusual property that may be useful for manufacturing new substances and the development of materials, according to new research.

Japanese researcher Hitoshi Kato says that close examination of the molecular activity that occurs in platinum coated catalytic convertors in cars shows that platinum nanoparticles behave in an unusual, if regular, pattern.

When platinum nanoparticles are heated to a high temperature they fuse together with the material they coat (sintering). Using an electron microscope, a team under Kato's supervision have discovered that platinum molecules actually 'burrow' into the surface of the zeolite they cover.

When the scientists examined a platinum coated zeolite surface after 100 hours of heating at 800°C and exposure to an atmosphere similar to a car exhaust, they found that the platinum particles effectively disappeared. The tiny pieces of precious metal had instead dug channels into the zeolite surface, leaving behind an intricate series of tunnels the size of the particles.  The platinum presumably catalyses a chemical reaction between the silicon and oxygen atoms in the zeolite and the components of the exhaust gases.  The platinum particles sink further into the zeolite as the reaction continues.

Kato told the Japan Fine Ceramics Centre that there were a number of applications for such a process.

'The observed phenomenon could be used to produce tailored porous materials,' hopes he commented.

'The number of pores, as well as their shape and size could be controlled by the diameter of the platinum particles, the duration of heating, the type of zeolite selected, and the orientation of the crystals.'

Posted 2^nd March 2004