Genhui Xu

Kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate over Pd-Fe/α-Al2O3 catalyst

The reaction kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate was studied in the presence of ethyl nitrite over supported palladium catalyst in gaseous phase at atmospheric pressure. The experiments were performed in a continuous flow fixed-bed differential type reactor. It was discovered that the rate-determining step is the surface reaction between adsorbed species and that ethyl nitrite dissociates into ethoxy radical (EtO−) and NO species and are adsorbed on two active sites. The kinetic model was proposed, with which some observations concerning with the reaction behaviors of the system can be readily accounted for. In the presence of hydrogen, the kinetics of the reaction system was also investigated. It was revealed that hydrogen, with adsorption and dissociation, reacts with adsorbed ethoxy radical to ethanol.

EFFECT OF Cu CATALYST PREPARATION ON THE OXIDATIVE CARBONYLATION OF METHANOL TO DIMETHYL CARBONATE

In this paper, the effect of catalyst preparation on the activity of supported Cu catalyst for oxidative carbonylation of methanol to dimethyl carbonate was investigated. The results showed that after addING metal hydroxide, the supported Cu catalyst enhanced the conversion of methanol and the selectivity TO of DMC and the suitable mole ratio of OH/Cu is 1.0. The optimum Cu content lies in 6-10 wt.% and varies with reaction temperature. The suitable calcination temperature range is 200-300oC considering both factors of methanol conversion and DMC selectivity. The effect of particle size of the catalysts on the activity is negligible.

Study on the reaction of CO coupling to oxalate

The synthesis of diethyl oxalate from ethyl nitrite and carbon monoxide in gaseous phase has been studied at atmospheric pressure. Kinetics of coupling - regeneration reaction has been determined and the optimization of the reaction has been simulated. The influences of gas impurities has also been studied. Scale-up circulating shows that the concentrate and selectivity were stable in the product and the process is suitable for industrial production.

Effect of Hydrogen on Catalytic Coupling Reaction of Carbon Monoxide to Diethyl Oxalate

The effect of hydrogen on catalytic coupling reaction of CO was tested at a temperature of 120 o C and residence time of 1.8 s. It was found that after introducing hydrogen to this system, ethanol was produced by H2 reaction with ethyl nitrite. With the increase of hydrogen concentration, the conversion of CO and H2 decreased and the selectivity of diethyl oxalate decreased too. The regeneration of the catalyst after removing hydrogen from the system was tested to prove reversible poisoning. The results show that the hydrogen concentration should be kept below 2 mol%.

Deactivation kinetics of a COcoupling reaction after addition of H2 to the system

The influence of hydrogen on the catalytic coupling reaction of CO was tested ar reaction temperatures of 105 120oC and a residence time of 1.8 s. The formation rate of diethyl oxalate (DEO) decreases with the addition of hydrogen to the system. Increasing hydrogen concentration and reaction temperature, the apparent rate of main reaction or the yield of DEO decreases more quickly. But the deactivation rate does not change with the relative activity. By correlating the experimental data, the deactivation kinetics was obtained.

Effect of oxygen on the activity of a Pd-Fe/a-Al2O3catalyst for CO coupling to diethyl oxalate

The effect of oxygen on the activity and selectivity of a Pd-Fe/a-Al2O3 catalyst for CO coupling to diethyl oxalate (DEO) was studied in the range of 105 - 120oC. The results showed that the conversion of CO and the STY (Space Time Yield) of DEO increased with increasing oxygen concentration from 5 to 10 mol% and reaction temperature, but the selectivity to DEO decreased. The role of oxygen in CO coupling is discussed on the basis of the experimental results in the present work and the XPS characterization of the catalysts. It was also found that the activity and selectivity of the catalyst could be fully recovered after removing O2 from the reaction system.