PrFeO_3上CO氧化脉冲及稳态动力学

The Pulse and Steady-State Kinetics of Oxidation for CO on PrFeO_3

ＰｒＦｅＯ_３用柠檬酸络合制备，ＰｒＦｅＯ_３经１０００℃灼烧４ｈ为钙钛矿结构，它经ＸＲＤ分析所验证．用ＣＯ还原催化剂及用Ｏ_２再氧化还原催化剂的脉冲实验证实，ＰｒＦｅＯ_３上ＣＯ氧化按Ｒｅｄｏｘ机理进行。用ＣＯ还原催化剂脉冲动力学方程，测定ＣＯ还原步骤的速度常数及其活化能。用外循环流动无梯度反应器研究了ＰｒＦｅＯ_３上ＣＯ氧化稳态动力学，其实验结果服从Ｒｅｄｏｘ机理动力学方程．并用正交设计法求出动力学参数值．

PrFeO_3 was prepared by the complex method with citric acid.It was calcinated in air at 1000℃ for 4 h.The perovskite structure was measured by XRD.The Redox mechanism of oxidatio for Co on PrFeO_3 was indicated by the reduction of catalyst with CO and reoxidation of the reduced catalyst with O2by the pulse method.The kinetic equation of reduction step with CO by pulse method obeyed the equation(3),while the rate constant of reduction step with pulse method has been measured by the equation(6)in the text. The activation energy of reduction step with pulse method,E1,is 56.6 kJ/mol.The steady-state kinetics of oxidation for CO on PrFeO_3 was investigated in a flow-recirculating gradientless reactor. The temperatures of reaction were in the range of 300-380℃.The effects of partial prassures of CO and O_2on the reaction rate were listed in Table 1.The steady-state kinetics of oxidation for CO was described by the Redox mechanism equation(11).The values of parameters in inetic equation(13) estimated by the method of orthogonal design are as follows:the frequency factors of Arrhenius equation for reduction and reoxidation steps are 4.6×10￣6(mol/g·h·kPa),1.60×10￣6(mol/g·h·kPa)respectively.The activation energies for reduction and reoxidation steps are 83.7 kJ/mol,97.8 kJ/mol respectively.