CO氢化合成乙醇反应的过渡应答研究——Ⅱ. 改性Rh/Al2O3催化剂上的反应动力学研究

本文用过渡应答技术研究CO在改性Rh/Al_2O_3催化剂上常压氢化合成乙醇的表面反应机理。结果表明: 1. 在Rh/Al_2O_3催化剂中添加K元素能显著地增加合成乙醇反应的活性和选择性; 2. 乙醇的生成取决于表面上相邻两个含氧中间体的密度而与气相中的H_2或CO浓度无关。反应倾向于ANDERSON的缩聚机理。在此反应机理的基础上, 由应答曲线的数据, 根据MARQUARDT非线性优化技术以及RUNG-KUTTA-GILL数值积分法计算了所有基元步骤的反应速率常数。

STUDIES ON THE SYNTHESIS OF ETHANOL FROM CO HYDROGENATION WITH THE TRANSIENT RESPONSE TECHNIQUE Ⅱ. THE REACTION MECHANISM OVER MODIFIED Rh/Al2O3 CATALYSTS

In the present paper the surface reaction mechanism with that the CO hydrogenation will proceed to ethanol is investigated by the transient response method using a quadrupole mass spectrometer under atmospheric CO-H_2 over Rh/Al_2O_3 and K doped Rh/Al_2O_3 catalysts. According to the experimental results, it is found that: 1. the presence of K causes a marked increase in the steadystate rate and selectivity for ethanol synthesis; 2. the formation of ethanol depends on the surface adjacent intermediates and is independent of the concentration of CO or H_2 in the gas phase, i.e. the results favor the condensation mechanism to the insertion mechanism.A mechanism of ethanol synthesis on the modified Rh/Al_2O_3 has been proposed and a set of rate constants of all elementary steps are calculated by Marquardt nonlinear optimization technique and Rung-Kutta-Gill numerical value integration method.