气体还原氧化铅的动力学数学模型

THE MATHEMATICAL MODEL OF THE KINETICS OF LEAD OXIDE REDUCED BY GASES

本文采用差重法,研究了氧化铅的气体还原动力学。实验结果表明,在一氧化碳气流中,当温度为530°～612°C 时,一氧化碳通过液态铅层的扩散为控制环节,还原的速率方程为(dn)/(dt)=(C_0)/x (D/(πt))^(1/2)扩散活化能为26.081 kcal/mol。当温度为412°～512°C 时,控制环节为界面化学反应,活化能为23.595 kcal/mol。在氧气还原过程中,还原速率由氢气在氧化铅表面的化学吸附所控制,速率方程为(dN)/(dt)=(AP)/(N_0(2πmkT)^(1/2))exp((E_a)/(RT))在温度为430°～551°C 的范围内,化学吸附的平均活化能为28.890 kcal/mol。在混合气体(CO+H_2)中,氢对氧化铅的还原过程影响突出。

In this paper the gas reduction kinetics of lead oxide have been investigated by thermogravimetry technique.The experimental results show that the reduction process of lead oxide in carbon monoxide flow was greatly affected by the product layer of liquid lead.In the temperature range of 530° to 612℃,the diffusion of carbon monoxide through this layer became controlling step.The rate prcoess of reduction is described by the following equation (dn)/(dt)=(C_o)/x=(D/(πt))^(1/2) The diffusion activation energy of 26.081kcal/mol was computed from the model.An activation energy obtained by the interracial chemical reaction model in the temperature range of 412°to 512℃ was 23.595kcal/mol. Tn hydrogen flow,the effect of temperature on the over-all rate was extreme.The reduction process is dominated by the chemisorption of hydrogen on the surface of lead oxide. The mathematical model of kinetics can be repre sented by -(dN)/(dt)=(AP)/(N_o(2πmKT)^(1/2))exp (-(E_a)/(RT)) The average activation energy of chemisorption in the temperature range of 430° to 551℃ was 28.890kcal/mol. The reduction process of lead oxide was affected by H_2 of (H_2+CO) gas mixtures.