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In order to resolve the problem of environmental pollution caused by nitrogen dioxide, it has been necessary to develop catalysts that decrease NOx in diesel engine emissions. Lean-burn engines that improve fuel efficiency have been developed for passenger cars that use gasoline, but the reduction of NOx is a problem that remains unresolved. Because the engine emissions of motor vehicles contain highly concentrated oxygen, the three-way catalyst now used for gasoline cars cannot decrease NOx. New catalyst technology must be developed. The Institute has succeeded in developing an epoch-making catalytic denitration method that works in an oxygen atmosphere and can be used with fuel-efficient engines. This method reduces and removes NOx using hydrocarbon and alcohol as reduction agents. Substances such as alumina and zeolite are used as catalysts. It has been confirmed that alumina catalysts exhibit higher activity and durability in activity tests using actual emissions from diesel engines. Studies are continuing for their practical application.
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