| Oxygen storage material has been used as an important component in automobile catalytic system, owing to containing the variable valence metals such as Co and Ce. The outstanding oxygen storage/release property can broaden the air/fuel ratio operation window of the three-way catalysts(TWCs), which can minimize the infleunce of air/fuel ratio fluctuation on the catalytic activity of TWCs during engine operation. Because homogeneous precipitation method has many advantages such as simple technology, convenient operation, high products concentration, the same particle size and composition, it is the most potential industrial method.In this paper, a series of new oxygen storage materials of YBa(Co0.9R0.1)4O7 were prepared by complexation method, and the effect of the substitution for Y with other matals was studied. The materials properties like oxygen storage capacity(OSC), thermal stability and texture-struture were characterized. The three-way catalysts Rh-Pd/YBa(Co0.9R0.1)4O7/?-Al2O3(M= Ce, Zr) were synthesized by impergnation method and their catalytic activities of fresh and aging samples were investigated. Meanwhile, Ce0.9-xZrx Al0.1O1.95 with different Ce/Zr ratios were prepared by homogeneous precipitation method, in which urea was used as precipitating agent, polyethylene glycol(PEG) as surfactant. The influences of the addition of PEG and urea, and the reaction temperature on the materials were studied. A muti-technique approach involving OSC, XRD, SEM, XPS, BET were operated.The results show that OSC of the YBa(Co0.9Zr0.1)4O7 sample which was calcined at 200?for 2 hours, 1000? for 5 hours was 3646.8 ?mol/g without obvious phase decomposition. The BET results of specific surface area, pore volune and average pore diameter were 17.97 m2?g-1, 0.1 cm3?g-1, 116.7 nm, respectively. Compared to fresh sample whose light-off temperature of CO, NO, HC was 273 ?, 287 ?, 288 ? respectively, the RhPd/YBa(Co0.9Zr0.1)4O7/?-Al2O3 aging sample's light-off temperature of CO, NO, HC was slightly increased after aged at 1000?,but it was maintaining high catalytic activity.When the molar ratio of urea and metal ions was 3:1, the mass ratio of PEG and expected products was 0.5:1, and reaction temperature was 25?, the OSC of fresh and aging samples of Ce0.6Zr0.3Al0.1O1.95 were 539.6 ?mol?g-1 and 506.4 ?mol?g-1 respectively. The BET results of fresh sample which were 17.97 m2?g-1, 0.1 cm3?g-1, 116.7 nm showed that Ce0.6Zr0.3Al0.1O1.95 prepared by homogeneous precipition method retaining the outstanding performance like high oxygen storage capacity and thermal stability. |
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