Temperature-programmed reduction (H2-TPR) was employed to quantitatively characterize the active oxygen species generated from a high Fe-loading Fe/ZSM-5 catalyst exposed to N2O at 250 ℃. Fe-O-Fe2+ dimer was determin...Temperature-programmed reduction (H2-TPR) was employed to quantitatively characterize the active oxygen species generated from a high Fe-loading Fe/ZSM-5 catalyst exposed to N2O at 250 ℃. Fe-O-Fe2+ dimer was determined as the active iron complex for N2O decomposition to produce the active oxygen. Reduction of Fe3+ to Fe2+ by H2 in the dimer and removal of OH- groups from Fe2+ dimer by heating Fe/ZSM-5 to 700 ℃ were the prerequisites for the formation of this active Fe complex. A linear correlation with a slope of 1.0 between the amount of Fe-O-Fe2+ and that of active oxygen species was observed. Maximum amount of active oxygen species can be generated by reducing Fe/ZSM-5 catalyst with H2 at the temperatures over 500 ℃ and then heating the resulting product in Ar to 700 ℃, followed by N2O exposure at 250 ℃.The ratio of the total number of oxygen atoms (Ode) deposited by interaction of Fe-O-Fe2+ with N2O to the amount of Fe-O-Fe2+ was 2. However, not all the deposited oxygen atoms were active oxygen (Oa); the ratio of Oa and Ode was 0.5. The iron dimer complex composing active oxygen is a five-atom ion Fe2O32+; the most probable structure is as follows:展开更多
The oxygen storage material (OSM) Ce0.35Zr0.55Y0.1O1.95 was prepared by co-precipitation routine and studied by means of TEM, XRD, XPS, BET, H2-TPR and oxygen storage capacity (OSC) measurements. The results indicated...The oxygen storage material (OSM) Ce0.35Zr0.55Y0.1O1.95 was prepared by co-precipitation routine and studied by means of TEM, XRD, XPS, BET, H2-TPR and oxygen storage capacity (OSC) measurements. The results indicated that this material possessed plenty of Ce3+ and lattice oxygen vacancy (percentage of Ce3+ was 59.6%) and high cerium atom utilization ratio (80.04%). The porous material was with an average BET surface area of 97 m2·g-1 and pore volume of 0.26 mL·g-1. After aged at 1 000 ℃ in air for 5 h, the sample still possessed plenty of Ce3+ and lattice oxygen vacancy (percentage of Ce3+ was 57.1%), and showed high cerium atom utilization ratio (78.25%), and high thermal stability.展开更多
文摘Temperature-programmed reduction (H2-TPR) was employed to quantitatively characterize the active oxygen species generated from a high Fe-loading Fe/ZSM-5 catalyst exposed to N2O at 250 ℃. Fe-O-Fe2+ dimer was determined as the active iron complex for N2O decomposition to produce the active oxygen. Reduction of Fe3+ to Fe2+ by H2 in the dimer and removal of OH- groups from Fe2+ dimer by heating Fe/ZSM-5 to 700 ℃ were the prerequisites for the formation of this active Fe complex. A linear correlation with a slope of 1.0 between the amount of Fe-O-Fe2+ and that of active oxygen species was observed. Maximum amount of active oxygen species can be generated by reducing Fe/ZSM-5 catalyst with H2 at the temperatures over 500 ℃ and then heating the resulting product in Ar to 700 ℃, followed by N2O exposure at 250 ℃.The ratio of the total number of oxygen atoms (Ode) deposited by interaction of Fe-O-Fe2+ with N2O to the amount of Fe-O-Fe2+ was 2. However, not all the deposited oxygen atoms were active oxygen (Oa); the ratio of Oa and Ode was 0.5. The iron dimer complex composing active oxygen is a five-atom ion Fe2O32+; the most probable structure is as follows:
文摘The oxygen storage material (OSM) Ce0.35Zr0.55Y0.1O1.95 was prepared by co-precipitation routine and studied by means of TEM, XRD, XPS, BET, H2-TPR and oxygen storage capacity (OSC) measurements. The results indicated that this material possessed plenty of Ce3+ and lattice oxygen vacancy (percentage of Ce3+ was 59.6%) and high cerium atom utilization ratio (80.04%). The porous material was with an average BET surface area of 97 m2·g-1 and pore volume of 0.26 mL·g-1. After aged at 1 000 ℃ in air for 5 h, the sample still possessed plenty of Ce3+ and lattice oxygen vacancy (percentage of Ce3+ was 57.1%), and showed high cerium atom utilization ratio (78.25%), and high thermal stability.
