Development of Catalytic NOx reduction

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CoAPSO-34 is a catalyst effective for selective NO reduction (SNR). SNR over Cu-SAPO-34 and Cu-CoAPSO-34 was studied in the presence of water vapor and SO_2 and found that SNR over Cu-SAPO-34 was retarded by the presence of water vapor and the NO conversion decreased by 10-20%. However, the addition of 200ppm SO_2 in the reaction system slightly depressed the NO conversion at 250-400ﾟC.Over Cu-CoAPSO-34, the presence of 7.0% water vapor in the reaction system brought about a small reduction (about 10%) in NO conversion over the temperatures examined and the incorporation of 200ppm SO_2 in this reaction system also decreased the NO conversion, however, it exceeded 40% at 300-400ﾟC.The structure of Cu-CoAPSO-34 was not changed after the reaction up to 500ﾟC.SO_2 will prefer to adsorb on Cu^<2+> at the catalyst surface than Co^<2+> and/or Co^<3+> located in the crystal lattice of SAPO-34. Because back donation of electrons of Cu^<2+> ions into adsorbed SO_2 molecules will be more feasible. When SV is so large as 32000h^<-1>, high NO conversion was maintained by the presence of relatively high concentration of C_3H_6,2000-3000ppm. A possible reaction mechanism was proposed by the experimental results using IR.