Engineers at a company co-founded by a University of Texas at Dallas professor have identified an oxide called mullite that may replace platinum in diesel engine emissions control systems.
In a paper published in the 17 August issue of the journal Science, Mixed-Phase Oxide Catalyst Based on Mn-Mullite (Sm, Gd)Mn2O5 for NO Oxidation in Diesel Exhaust, by W Wang et al, researchers describe how they found that when a synthetic version of the oxide mullite replaces platinum, tailpipe NOx emissions are up to 45% lower than with platinum catalysts. Dr Kyeongjae ‘KJ’ Cho, Professor of Materials Science at UT Dallas and a senior author of the study, said, “Mullite is not only easier to produce than platinum, but also better at reducing pollution in diesel engines.”
In 2003, Cho co-founded and became the lead scientist of Nanostellar, a company created to find catalysts through material design that would replace platinum in reducing diesel exhaust. Nanostellar has designed and commercialised a platinum-gold alloy catalyst that is a viable alternative to platinum alone, but until this experiment with mullite, had not found an equally effective catalyst material that is less expensive than platinum.
Professor Cho synthesised mullite, a mineral originally found off the Isle of Mull in Scotland, and used advanced computer modelling techniques to analyse how different forms of the mineral interacted with oxygen and NOx.
The mullite platinum substitute is being marketed under the trademark ‘Noxicat’. Nanostellar is also planning to explore other applications for mullite beyond NOx catalysis, including the replacement of platinum in PEM fuel cells.
