Ferric Catalyst DeNOxProcesses by Utilization of CarbonMonoxide from Vehicle Exhaust

摘要

In this study, two iron oxide catalysts ( -Fe2O3, 45 m and FeOOH, manufactured in thelaboratory) were utilized to evaluate carbon monoxide, emitted by engine exhaust with Noxsimultaneously, as a reductant for deNOxprocess by packed bed reactor. Four reactionparameters were adopted: reaction temperature, NO influent concentration, CO influentconcentration and -Fe2O3/ FeOOH dosage. Possible reaction steps were investigated byXRD spectrum.In -Fe2O3catalyst system, effective temperature was 673~773 K and NO removalefficiencies were 81~95 % for NO influent 240~720 ppmv and CO influent 1910 ppmv,respectively. NO removal of 4 % was observed for CO concentration 955 ppmv, but wasincreased to 95 % for CO concentration 1910 ppmv in 773 K and stayed 95 % NO removalfor CO influent up to 3820 ppmv. It was showed molar removal ratio RNO/RCO was linearlycorrelated to influent concentration ratio [NO]in/ [CO]in due to reduction of NO and oxidationof CO were simultaneously occurred. -Fe2O3dosage also affected NO removal efficiency,where -Fe2O3dosage was controlled above 2.g for 95 % NO removed at 240 ppmv in 773K.In FeOOH catalyst system, effective reaction temperature was 523 K~723 K for over 98 %NO removed with NO influent 720 ppmv and CO influent 1910 ppmv. Lower CO influentconcentration 478 and 955 ppmv decreased NO removal efficiency to 0 and 44.6 % in 523 Kdue to lack of sufficient activated iron sites provided by CO / FeOOH reaction. It wasobserved as CO influent 1910 ~2980 ppmv, the CO reacted efficiency was decreased, andNO removal efficiency was still kept in 100 % due to CO / FeOOH reaction provide stablyreduction reaction for NO to convert to N2.Moreover, XRD (XrayDiffraction) was used for demonstration of catalytic reactionsamong CO, NO, -Fe2O3,and FeOOH.