New formula for cheaper catalysts

In a finding that provides an important boost to vehicle emissions control technology, a

research team has discovered a novel formulation to operate pollution-dampening catalytic converters without the need for expensive noble metals.

The novel formulation is designed for a relatively new vehicle engine technology that provides for high fuel efficiency. Such lean burn engines, which can save up to 20 percent on fuel consumption over engines now in use, are being road tested in several countries, including South Africa and Japan, but they are not yet on the market. These new engines require new catalysts because the 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 both 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 has achieved positive results by using the less expensive cobalt as an oxidising metallic element. “This has proved to be superior in performance, and a lot cheaper, than the best catalytic converter materials known,” Lauterbach said.

Successful combinations

The UD team is a pioneer in combinatorial materials science, a method by which the engineers can look at many potential catalysts at once rather than going through the laborious process of studying the materials one by one.

“The idea is to look at multiple materials in parallel, rather than one at a time,” Lauterbach said. “Now we can look at anywhere from a dozen to a hundred materials in the same amount of time as we previously could look at one. As a result, we can look at material compositions that we wouldn’t have been able to study before, simply because of the time involved.”

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 five percent cobalt and 15 percent barium was just as effective as conventional formulations that contain one percent platinum.

Furthermore, the UD scientists found that by adding platinum to the cobalt-barium 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-of-the-art 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.”

The UD scientists now are working to optimise the composition of the material, in terms of both cost and long-term stability.

Lauterbach said he believes the findings should be of great interest to both government and industry. “The

government is funding research on hydrogen fuel, which might save us 50 years from now but won’t make us less dependent on foreign oil in the next few years,” he said. “If the technology is there and you can save fuel, it presents an opportunity to reduce dependence on foreign oil.”