The Engineer (http://www.theengineer.co.uk/) reports that a material has been identified that can significantly reduce the pollution produced by vehicles that run on diesel. “In a study published in Science, researchers found that pollution is up to 45% lower when a man-made version of the oxide mullite replaces platinum in diesel catalytic converters,” it says. Dr Kyeongjae ‘KJ’ Cho, Professor of Materials Science and Engineering and Physics at the University of Texas at Dallas is a senior author of the study. He says “mullite is not only easier to produce than platinum, but also better at reducing pollution in diesel engines.”In 2003, Cho became a co-founder and lead scientist at Nanostellar, a company created to find catalysts through a material design that would replace platinum in reducing diesel exhaust. His research team suspected that the oxygen-based composition of mullite might prove to be a suitable alternative.
Cho’s team used advanced computer modelling techniques and confirmed the efficiency of mullite to consume NOx. Researchers used the oxide catalyst to replace platinum in diesel-engine experiments.
The mullite alternative is being commercialised under the trademark name NoxicatTM. On August 18 Nanostellar announced that the paper based on its Noxicat catalyst has been published in the August 2012 issue of Science. Noxicat has already received considerable interest from manufacturers of light-duty and heavy-duty diesel engines for its ability to help engine manufacturers reduce harmful greenhouse gas emissions while dramatically reducing the cost of doing so.
“We achieved the goal of finding a NO oxidation catalyst that performs better than platinum, does not use any precious metals and is hydrothermally stable” remarked Geoffrey McCool, who invented this material. Noxicat is stable within diesel exhaust temperature range, while platinum based solutions tend to sinter and loose activity when exposed at temperatures higher than 750oC. This novel material starts being active at temperatures as low as 120oC with NO to NO2 conversion maxima of ~45% higher than that achieved with Pt after prolonged thermal aging. Structurally, the active site was found to be a Mn-Mn dimer on stepped mullite surfaces. “According to my density functional theory calculations, Noxicat’s active site has a comparable rate limiting step to that of platinum,” stated Weichao Wang, leading author of the Science article.
“In addition to significantly reducing the costs of emissions control systems, Noxicat has numerous performance benefits over the incumbent platinum based catalysts” commented Pankaj Dhingra, Nanostellar’s President and CEO. “Noxicat enables higher fuel efficiency by allowing engine designers to reduce the frequency of filter regeneration events and allows for redesign of the emissions control system for further optimisation.”
Dr. Bulent Yavuz, Nanostellar’s VP of sales and marketing who has been monitoring the reaction of early customers stated that “Noxicat has created an unprecedented level of excitement among heavy-duty diesel engine manufacturers for both its performance benefits and its promise of significant cost reductions. The commercialization efforts received a further boost when customer testing revealed that Noxicat is able to regenerate itself after exposure to fuel-borne sulphur.”