Conversion Of NO With Microwave Irradiation

Microwave irradiation assisted catalysis consists of microwave heating assisted catalysis and microwave discharge assisted catalysis. The former has been investigated extensively in organic chemistry, and novel results have been obtained. However, few reports have been focused on the catalysis by microwave discharge. In the present dissertation, the effects of coupling microwave irradiation and catalysis on catalytic reduction of NO were investigated. For the first time, the microwave discharge assisted catalytic reduction of NO by CH4 was investigated. The conversion of NO to N2 was approximately 100% over a Ni( I 0%)IHZSM-5 catalyst by this method, and the reaction temperature could be lowered remarkably. By analyzing the reaction results, the possible action of the method is suggested. Furthermore, the microwave discharge decomposition of NO was investigated for the first time with a special reactor at atmospheric pressure. The one-step conversion of NO to N2 approximated to 9O扸o by this method. The effects of various reaction parameters on NO conversion were also studied. By analyzing the reaction mechanisms, it is drawn that the advantage of microwave discharge is the direct activating of the reactants in the gas phase. Then, the effects of microwave heating on the catalytic reaction were studied. The results showed that the range of the active temperature was widened clearly and the temperature for running the catalytic reaction could be lowered when the reduction of NO by CH4 was assisted by microwave heating. Furthermore, the catalytic decomposition of NO assisted by microwave heating was also investigated for the first time. The conversion of NO to N2 was up to 70% by microwave heating over an Fe/NaZSM-5 catalyst. The tolerance of 02 was better for the catalyst under such conditions. The local heating sites formed by microwave heating were identified to be catalytic active sites. The reaction mechanism was discussed basing Ill on characterization results of the catalysts by FTIR~ MBS and XPS, etc., before and after the experiments. The action of microwave heating on the catalytic decomposition of NO involved three factors which were related on the local heating effects. Finally, it was observed for the first time that the automotive emission could be purified by the microwave heating assisted catalytic method. The results showed that the method could widen the air/fuel ratio window of the catalyst and lower the light-off temperature.