The mineral cryptomelane holds promise to absorb the toxic sulfuroxides that can degrade the emission control systems on dieselvehicles. Pacific Northwest National Laboratory researchers haveidentified the potential for using cryptomelane to trap sulfur dioxideand 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-basedabsorbents. Finding a way to capture sulfur is important since mostfuels have a sulfur content that is harmful to the environment, clogsemissions control devices or damages fuel cells.
PNNL researchers tested cryptomelane under diesel engine conditionsthat are being proposed to trap nitrogen oxides – the most dangerouscomponent of diesel exhaust. Under those conditions, including hightemperatures, the cryptomelane maintains its very high sulfur dioxidecapacity. These studies indicate that cryptomelane can be used toprotect the nitrogen oxides traps from the sulfur oxide that degradesthem under these conditions.
Finding cryptomelane to be an excellent catalyst for oxidizingsulfur dioxide, PNNL researchers have filed for a patent on thisapplication. They believe the catalyst may degrade additionalundesirable material and are looking for research partners todemonstrate the usefulness of cryptomelane.
Pacific Northwest National Laboratory researcher Liyu Li presented his results Thursday, Sept. 1.
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