色谱法测定乙醇扩散系数及乙醇深度氧化的内扩散影响

DETERMINATION OF DIFFUSIVITY OF ETHANOL BY CHROMATOGRAPHIC METHOD AND EFFECT OF INTERNAL DIFFUSION ON ETHANOL COMPLETE OXIDATION

用脉冲色谱峰加宽非稳态法测定乙醇在Ｐｔ／Ａｌ_２Ｏ_３催化剂中４００～４８０℃之间的有效扩散系数。乙醇孔扩散活化能为５．４６ｋＪ／ｍｏｌ。当用０．４５～０．６０ｍｍ催化剂时，乙醇的完全氧化在动力学区域进行，氧分压过量时，此区域的反应速度遵循乙醇０．１级速度方程。当催化剂颗粒增大至５ｍｍ时反应受乙醇内扩散控制。在内扩散区域乙醇的反应级数为０．５５级。动力学区域的反应活化能为３５．９ｋＪ／ｍｏｌ，内扩散区域的活化能为１５．７ｋＪ／ｍｏｌ。

The effective diffusivity of ethanol in platinum-alumna catalyst has been measured by the chromatographic peak-broading unsteady-state technique in the temperature ranging from 400-480℃,The activation energy of pore diffusion of ethanol is 5.46kJ/mol.The complete oxidation of ethanol appears in the kinetic region on catalyst with 0.45-0.60mm.Under the excess of partial pressure of oxygen,the rate of reaction in this region follows the rate equation of 0.1 reaction order of ethanol.When the catalyst size increases to 5mm,the reaction is controlled by the internal diffusion of ethanol, and the reaction order changes to 0.55 order of ethanol.The activation energy of reaction is 35.9kJ/mol in the kinetic region,but 15.7kJ/mol in the internal diffusion region.