Study on the Mechanism of Carbon/NO_x Reaction by Using Isotopes

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Nitrogen oxide reduction with carbon has been studied as a possible way to eliminate this pollutant involved in the ozone layr depletion, acidic rain falls and global warming. In order to obtain the fundamental reaction pathways occurring in the fluidized bed reactor, we have studied the reaction mechanism between carbon and NO_x and N_2O.The principal technique used was the step response experiments using isotope gases. For example, by switching the reactant gas from ^<15>N^<18>O to ^<14>N^<16>O,we can speculate the behavior of surface ^<15>N species or surfhce ^<18>O species during the reaction with ^<14>N^<16>O.From these experiments, it was clearly concluded that the main N_2 formation during C-NO reaction is the reaction between C (N) and NO.By using a similar technique, we also clarified the reaction mechanism between carbon and N_2O.During the reaction of carbon with a mixture of ^<14>N2^<16>O and ^<15>N_2^<16>O,no formation of ^<14>N^<15>N was observed, suggesting the splitting of N_2 from N_2O without N-N bond breakage.The simulation of these reactions were also studied by using molecular orbital calculation, and we found that the above mechanisms are quite reasonable.