Pt/C催化氧化甲醛和甲酸反应动力学研究

Kinetic Study on Formaldehyde and Formic Acid Oxidation Catalyzed by Pt/C

目前草甘膦工业生产母液含大量甲醛,今采用Pt/C催化剂在反应过程中催化氧化甲醛以期提高母液循环套用效率。运用自制Pt/C催化剂研究甲醛和甲酸的氧化反应及其动力学。XRD和TEM测定表明,Pt/C催化剂中Pt的平均粒径为1.4 nm,分散性较好。消除内、外扩散影响后在反应压力0.6 MPa、搅拌转速800 r×min^(-1)、氧气流量120 mL×min^(-1)及反应温度323.15~353.15 K的条件下进行甲醛和甲酸氧化反应动力学实验,建立本征动力学模型并运用实验数据进行拟合计算得到动力学参数,甲醛氧化生成甲酸反应活化能为36.04 k J×mol^(-1),甲酸氧化反应活化能为19.93 k J×mol^(-1),甲醛与甲酸的吸附热分别为-60.26 k J×mol^(-1)和-39.96 k J×mol^(-1)。

Glyphosate production in industry often results in large amount of formaldehyde in mother liquid.Pt/C catalysts were applied in the oxidation of formaldehyde to improve recycling efficiency of mother liquid inthis study.The oxidation reaction kineties of formaldehyde and formic acid were investigated usinglab-prepared Pt/C catalysts.XRD and TEM results show that Pt particles are well dispersed with an averagediameter of1.4nm.Reaction studies were performed under conditions of reaction pressure0.6MPa,stirringspeed800r.min-1,oxygen flow rate120mL.min-1and reaction temperature323.15~353.15K with internal andexternal diffusion resistance eliminated.Kinetics model is established and its parameters are obtained via datafitting.The activation energies for oxidation of formaldehyde and formic acid are36.04kJ.mol-1and19.93kJ.mol-1,respectively,and the adsorption heats of formaldehyde and formic acid are-60.26kJ.mol-1and-39.96kJ.mol-1,respectively.