Study On Macro-kinetics Of CO Catalytic Coupling Reaction To Diethyl Oxalate In Gaseous Phase

The thermal decomposition of ethyl nitrite (EN) and the catalytic decompositionover catalyst, support and metal iron with EN mole concentration from 15% to 25%were investigated. The results showed that the thermal decomposition of EN wasnegligible when the temperature was below 120℃ while the thermal decompositionincreased greatly with the increase of temperature when the temperature was above170℃. The decomposition of EN over γ-Al2O3 is larger than that over α-Al2O3because of the stronger acidity of γ-Al2O3. When the residence time and ENconcentration are less then 1.2s and 20% respectively, the decomposition of EN overPd catalyst was below 8% at temperature below 120℃. The decomposition of ENincreased with the increase of residence time, temperature and EN concentration.These were important to determine the optimum CO coupling reaction conditions.The experiments were carried out on Pd catalyst at the optimum CO couplingreaction conditions of temperature 110℃～130℃, residence time 0.7s～1.1s, ENmole concentration 10%～15% and CO mole concentration 25%～35%. Runge-Kuttamethod and simplex type method were used to optimize these data and themacro-kinetics of CO coupling reaction was simulated using power model asfollowing:One dimensional quasi-homogeneous model was used to simulate the COcoupling reactor for 300t/a oxalic acid production in pilot plant. The effects ofoperating parameters and feed composition on the reaction were investigated. Theresults showed that at residence time 2.4s and the reaction temperature of 393K and403K, the ethyl nitrite was converted completely at the catalyst bed height of 2m and1.5m respectively. In addition, the space time yield of diethyl oxalate increased withthe increase of the concentration of CO and EN. These provide theoretical foundationand guidance for simulating and scaling-up of the reactor.