在Pt/Al_2O_3催化剂上内扩散对异丁醇完全氧化动力学的影响

The Influence of Internal Diffusion on the Kinetics of Complete Oxidation of Iso-butyl Alcohol over Pt/Al_2O_3 Catalyst

用外循环无梯度反应器研究了内扩散对异丁醇完全氧化动力学的影响。当催化剂颗粒在30～40目时反应在动力学区域进行。异丁醇完全氧化的动力学方程服从异丁醇及O_2吸附,CO_2吸附阻碍的L-H模型。当催化剂颗粒增大到4mm时,异丁醇完全氧化发生在内扩散区域。催化剂有效因子在0.47～0.75之间。它表明反应受内扩散控制。内扩散区域的表观活化能为动力学表观活化能及O_2分子扩散活化能之和的一半。用常微分方程的试射法及梯形法标出O_2在催化剂孔内的压力分布。

The influence of internal diffusion on the kinetics of complete oxidation of iso-butyl alcohol was investigated by the external circulation gradientless reactor. When the size of catalyst was within the range of 30-40 mesh, the reaction occured in the kinetic region. The kinetic equation for complete oxidation of iso-butyl alcohol obeyed the L-H model of adsorption of iso-butyl alcohol and oxygen with inhibition of carbon dioxide. When the particle size increased to 4 mm, the complete oxidation of iso-butyl alcohol occured in the internal diffusion region. The effectiveness factors of catalyst ranging from 0.47 to 0.75 showed that the rate of reaction was limited by the internal diffusion. The apparent activation energy of reaction in the internal diffusion was 23.5kJ/mol, just the one-half of the sum of that in the kinetic region and activative energy for diffusion of molecular oxygen. The pressure profile of oxygen in the pore of catalyst was calculated by the combination of Shooting method and trapezoidal method of ordinary equations.