Abstract: 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.