Kinetics of the Hydrogenation of Diethyl Oxalate to Ethylene Glycol

摘要

The reaction kinetics of the catalytic hydrogenation of diethyl oxalate to ethylene glycol in the vapor phase over a copper-base catalyst were studied. The experiments were carried out in a continuous flow microreactor. The experimental work was based on the following consecutive reaction scheme: C_2H_5COOCOOC_2H_5 + 4H_2 ←→ HOCH_2CE_2OH + 2C_2H_5OH; HOCH_2CH_2OH + H_2 → C_2H_5OH + H_2O. Fourteen competing kinetic models obtained from the possible mechanisms have been proposed for the above scheme. By fitting the experimental data to each model, the following rate equations were found to best fit the data: r_1 =[k_1K_(ox)K_H(p_(ox)p_H -p_(EG)P_E)~2/(K_pP_H)~3]/(1 + K_(ox)p_(ox) + (K_Hp_H)~(1/2) + K_(EG)p_(EG) + K_EP_E)~3; r_2 = k_2K_(EG)K_Hp_(EG)p_H/(1 +K_(ox)p_(ox)+ (K_Hp_H)~(1/2) + K_(EG)p_(EG) + K_Ep_E)~3. In the model from the above rate equations were obtained the hydrogenation reaction of diethyl oxalate follows the Langmuir-Hinshelwood mechanism in which hydrogen adsorbs dissociatively. The surface reaction step was rate-limiting for both the main and side reaction.