Doping catalysts for lean burn engines
There's no denying it. Automobiles pollute the environment. And while today's cars are much cleaner than their predecessors, there are so many more cars on the road that their collective impact is worse than ever. Lean burn engines show promise. Lean burn engines employ a higher air-to-fuel ratio, resulting in considerably improved fuel economy. However, the three-way catalysts that clean the exhaust of typical engines don't work as well on lean burn engines. New catalysts have to be developed in order for the benefits of lean burn engines to be realised. A European research group led by the University of Patras in Greece has made progress against this goal. They did so by applying some radical techniques to traditional catalyst materials. One technique, Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA), introduces a solid electrolyte which helps amplify chemical reactivity. In addition, Dopant-Induced Metal-Support Interaction (DIMSI) induces further alterations in the material's chemisorptive and catalytic properties. Some engineering firsts were achieved during the research, such as demonstrating NEMCA in a bipolar configuration. Manipulating rhodium-based mono- and bimetallic catalysts with NEMCA and DIMSI, the group was able to significantly intensify NOx conversion in the presence of molecular oxygen. Equally important was the fact that this increased catalysis was possible over a wider than normal range of operating temperatures. The work, supported by the Fourth Framework Programme, has relevance not only for catalyst development for lean burn engines, but also for diesel engines. While the advantages of the NEMCA and DIMSI techniques have been proven, both separately and in conjunction, further research is necessary prior to industrial implementation.
