环境催化技术　全套课件下.PPTVIP

0 20 40 60 80 100 Without catalyst AC Pd/AC Pt/AC Ru/AC Re/AC % Decomposition of NH4NO3 over AC supported metal catalysts Pt/AC: Conversion over 90% - Capable to decompose NH4NO3 Simultaneously The major product is N2 however, N2O was also formed. -No significant formation of NO, NO2 and NO2-. Metal loading: 3 wt%, air at 1.0 MPa 453 K, 2 h NH4+ conversion N2O selectivity NO3- conversion Correlation between the activity and affinity to oxygen -ΔHf?, kJ / g-mol PtO PdO RuO2 ReO3 NH4+ conversion NO3- conversion Metals with low affinity to oxygen exhibit high activity to the decomposition. Reactivity of surface bounded oxygen is more important than concentration of oxygen on metal surface. Low Affinity to oxygen High 0 20 40 60 80 100 % 　Pd/AC Pd/MgO Pd/Al2O3 Pd/ZrO2 Pt/AC Pt/MgO Pt/TiO2 ? AC supported catalysts exhibited excellent activity. - Significant formation of CO2 --AC works as reducing reagent. NH4+ conversion N2O selectivity NO3- conversion No considerable activity loss by repeated usage. Metal loading, 3 wt%; air at 1.0 MPa 453 K, 2 h Decomposition of NH4NO3 over AC supported Pd and Pt catalysts Reaction temperature dependence Feed-gas, 0.5 MPa of air 0 20 40 60 80 100 400 420 440 460 Reaction temperature / K % NH4+ conversion NO3- conversion N2O selectivity 2 wt% Pt/AC Conversion reached 100% at 443 K. N2O selectivity was slightly dependent on the reaction temperature and at 5% or low. Dependence on initial NH4NO3 concentration 2 wt% Pt/AC, Feed-gas, 0.5 MPa of air　 Increasing initial concentration gave slight increase in N2O selectivity. NH4+ conversion NO3- conversion N2O selectivity Complete conversion of both ions was observed even with initial concentration of 0.5 mol/L. High potential to the application to industrial NH4NO3 decomposition processes. 0 20 40 60 80 100 0 1 2 3 4 Air feed pressure / MPa % Dependence of catalysis on gas-feed pressure NH4+ conversion NO3- conversion N2O selectivity O2/Ar ratio Conve