Machine Design

Your next catalytic converter: Cobalt

A University of Delaware research team claims they have discovered a novel formulation for catalytic converters that eliminates the need for expensive noble metals.

The novel formulation is designed for relatively new lean-burn engines. These engines are being road tested in several countries, including South Africa and Japan, but are not yet commercially available. Lean-burn engines need new catalysts because existing catalysts do not work under the exhaust conditions the engines create.

The formulation developed by Jochen A. Lauterbach, UD associate professor of chemical engineering, and colleagues is claimed to be cheaper and more effective than the current means of catalytic conversion, which relies on the use of costly platinum in the storage and reduction of nitrogen oxides in the emissions.

The UD research team uses cobalt as an oxidizing metallic element. The idea for this new class of catalysts was drawn from research undertaken by Toyota Motor Corp.

UD team members credit what is called combinatorial materials science for insights into the new catalysts. "The idea is to look at multiple materials in parallel, rather than one at a time," Lauterbach said. "Now we can examine anywhere from a dozen to a hundred materials in the same amount of time needed previously to look at one. As a result, we can scrutinize material compositions that we wouldn't have been able to study before, simply because of the time involved."

Lauterbach's research team was just the second academic group in the U.S. to work in combinatorial catalysis and remains one of the leading groups in the nation in that field. The UD group can test 16 catalysts at once, studying the effect of small concentrations of manganese, iron and cobalt on the performance of nitrogen oxide storage and reduction catalysts.

The scientists found that an alumina-supported catalyst containing 5% cobalt and 15% barium was just as effective as conventional formulations that contain 1% platinum.

Furthermore, the UD scientists found that by adding platinum to the cobaltbarium catalyst they could produce a material with twice the nitrogen-oxide storage capacity of traditional platinum-based catalysts.

"Our primary finding, really, is in performance," Lauterbach said. "Using the cheaper material, the performance is equal to the most-expensive state-oftheart equipment. And, if you add the higher priced materials, you see a substantial increase in performance over what is shown in the most recent literature."

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