August 24, 1998This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. PREPRINTThis paper was prepared for submittal to the DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. ABSTRACTMany studies suggest that lean-NO x SCR proceeds via oxidation of NO to NO 2 by oxygen, followed by the reaction of the NO 2 with hydrocarbons. On catalysts that are not very effective in catalyzing the equilibration of NO+O 2 and NO 2 , the rate of N 2 formation is substantially higher when the input NO x is NO 2 instead of NO. The apparent bifunctional mechanism in the SCR of NO x has prompted the use of mechanically mixed catalyst components, in which one component is used to accelerate the oxidation of NO to NO 2 , and another component catalyzes the reaction between NO 2 and the hydrocarbon. Catalysts that previously were regarded as inactive for NO x reduction could therefore become efficient when mixed with an oxidation catalyst. Preconverting NO to NO 2 opens the opportunity for a wider range of SCR catalysts and perhaps improves the durability of these catalysts. This paper describes the use of a non-thermal plasma as an efficient means for selective partial oxidation of NO to NO 2 . When combined with some types of SCR catalyst, the plasma can greatly enhance the NO x reduction and eliminate some of the deficiencies encountered in an entirely catalyst-based approach.

August 24, 1998This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. PREPRINTThis paper was prepared for submittal to the DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. ABSTRACTMany studies suggest that lean-NO x SCR proceeds via oxidation of NO to NO 2 by oxygen, followed by the reaction of the NO 2 with hydrocarbons. On catalysts that are not very effective in catalyzing the equilibration of NO+O 2 and NO 2 , the rate of N 2 formation is substantially higher when the input NO x is NO 2 instead of NO. The apparent bifunctional mechanism in the SCR of NO x has prompted the use of mechanically mixed catalyst components, in which one component is used to accelerate the oxidation of NO to NO 2 , and another component catalyzes the reaction between NO 2 and the hydrocarbon. Catalysts that previously were regarded as inactive for NO x reduction could therefore become efficient when mixed with an oxidation catalyst. Preconverting NO to NO 2 opens the opportunity for a wider range of SCR catalysts and perhaps improves the durability of these catalysts. This paper describes the use of a non-thermal plasma as an efficient means for selective partial oxidation of NO to NO 2 . When combined with some types of SCR catalyst, the plasma can greatly enhance the NO x reduction and eliminate some of the deficiencies encountered in an entirely catalyst-based approach.

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