Preparation and catalytic oxidation activity of Pr_(2-x)Sr_xCoO_(4±λ) with K_2NiF_4
The mixed oxides Pr_2-xSr_xCoO_4±λ (0.2≤x≤1.0) with K_2NiF_4 structure were synthesized by the po lyglycol gel method.The composition and structure of the catalysts were characte rized by means of XRD,TPD,TPR,XPS,and chemical analysis.The catalytic performanc e for CO and C_3H_8 oxidation was investigated.The results showed that the mix ed oxides displayed K_2NiF_4 structure.Other phases were found when x=0.2 and x=1.0 and the mixed oxide was single A_2BO_4 when 0.2x1.0.Wi th the increase of x, average crystalline size, unit cell volume and lattice parameters of Pr_2-xSr_xCoO_4±λ catalysts decreased g radually, however, the concentration of oxygen vacancy, the desorption amount of lattice oxygen, the amount of Co3+, and lattice distortion increased grad ually.There were only the desorption peak approaching BE (529 eV) in the O_1s curves of Pr_2-xSr_xCoO_4±λ catalysts when x=0 .2 and x=0.4.However, the O_1s curves of Pr_2-xSr_xCoO _4±λ catalysts, when x=0.6—1.0,included two peaks, and the pea k areas approaching BE (531 eV) increased with the increase of x.The catalyt ic activities for CO and C_3H_8 oxidation were closely correlated with oxygen vacancy, lattice oxygen and Co3+.