Preparation of Titanium-Zirconium Mixed Oxide and its Catalytic Performance of Pt Three-way Catalysts

Zr_(0.5)Ti_(0.5)O_2 mixed oxides were prepared by co-precipitation method.The effects of pH value,precipitation temperature and calcination temperature of Zr_(0.5)Ti_(0.5)O_2 on its specific surface area, pore size,pore volume and surface acidity were investigated.The samples calcined at 500℃,550℃, 600℃,650℃,700℃,800℃for 2h,were characterized by means of BET,X-ray diffraction (XRD) and NH_3-temperature programmed desorption (NH_3-TPD).Using the Zr_(0.5)Ti_(0.5)O_2 and La-Al_2O_3 as catalyst carriers,and the activities of Pt/Zr_(0.5)Ti_(0.5)O_2 and Pt/La-Al_2O_3 catalysts were evaluated in the simulated gas.The results show that when the pH is 11,precipitation temperature is 25℃,calcina- tion temperature is 550℃,Zr_(0.5)Ti_(0.5)O_2 exhibits the highest specific surface area(195m~2·g~(-1)),larger pore volume(0.28mL·g~(-1)),proper surface acidic amount and acidity.Compared with Pt/La-Al_2O_3, Pt/Zr_(0.5)Ti_(0.5)O_2 exhibits excellent low-temperature catalytic activity and lower the light-off tempera- ture of hydrocarbon (234℃) and carbon monoxide (203℃) and nitrogen oxides (213℃).At the same time,it is found that the Pt/Zr_(0.5)Ti_(0.5)O_2 catalysts significantly improve the conversion for nitrogen oxides.