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 proeced to ethanol is investigated by the transient response method using a quadrupole mass spectrometer under atmospheric CO-H-2 over Rh/Al2O3 and K doped Rh/Al2O3 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/Al2O3 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.