Super sulfur soaker material may help control diesel emissions

The mineral cryptomelane holds promise to absorb the toxic sulfur oxides that can degrade the emission control systems on diesel vehicles. Pacific Northwest National Laboratory researchers have identified the potential of using cryptomelane to trap sulfur dioxide and sulfur trioxide from diesel engine emissions on monolith supports – sturdy honeycombed structures composed of small parallel channels.

Cryptomelane has a very high capacity for absorbing sulfur dioxide – more than 10 times as high as those of standard metal oxide-based absorbents. Finding a way to capture sulfur is important since most fuels have a sulfur content that is harmful to the environment, clogs emissions control devices or damages fuel cells.

PNNL researchers tested cryptomelane under diesel engine conditions that are being proposed to trap nitrogen oxides – the most dangerous component of diesel exhaust. Under those conditions, including high temperatures, the cryptomelane maintains its very high sulfur dioxide capacity. These studies indicate that cryptomelane can be used to protect the nitrogen oxides traps from the sulfur oxide that degrades them under these conditions.

Finding cryptomelane to be an excellent catalyst for oxidizing sulfur dioxide, PNNL researchers have filed for a patent on this application. They believe the catalyst may degrade additional undesirable material and are looking for research partners to demonstrate the usefulness of cryptomelane.