Catalytic converters rely on particles of metal to spur reactions that transform vehicle-exhaust pollution into less-hazardous carbon dioxide, water, and nitrogen.
Unfortunately, the metal particles in use today stick together when exposed to engine heat. That shrinks the overall metal surface area available, making the catalysts less efficient. Carmakers compensate for this problem by loading converters with extra catalyst, an expensive practice since the metals are usually costly ones, such as palladium and platinum.
By taking a new look at a long-known catalyst, Yasuo Nishihata of the Japan Atomic Energy Research Institute (JAERI) in Mikazuki and his colleagues may have found a way to build effective converters with less metal. The catalyst, which was first studied for use in catalytic converters in the early 1970s, includes the mineral perovskite with palladium (SN: 1/12/02, p. 23: New structure reveals catalysts’ details).
The researchers found that when they cycled their palladium-perovskite catalyst through oxygen-rich and oxygen-poor conditions, the catalyst particles retained their configuration and, presumably, their efficiency. Similar oxidizing-reducing cycles occur in modern automobile exhausts a few times each second, says Nishihata.
The research team from JAERI, Daihatsu Motor Co. in Ryuo, Toyota Central R&D Laboratories in Nagakute, and the Tokyo University of Science in Noda reports its results in the July 11 Nature.