Kinetics of ethylene combustion in the synthesis of vinyl acetate over a Pd/SiO2 catalyst

The kinetic parameters of ethylene combustion in the presence of acetic acid, i.e., during the synthesis of vinyl acetate and in the absence of acetic acid, have been measured in the temperature range 413–453 K over Pd supported on a high surface area SiO2 (600 m2/g) at pressures ranging from 5.0 to 15.0 kPa of C2H4 and 1.0 to 10.0 kPa of O2. CO2 formation as a function of the partial pressures of C2H4 and O2 exhibited a negative reaction order with respect to C2H4 and a positive order with respect to O2. The kinetic parameters of ethylene combustion in the presence and absence of acetic acid were essentially the same, consistent with ethylene combustion being primarily responsible for CO2 formation in the synthesis of vinyl acetate from ethylene and acetic acid over unpromoted Pd within the pressure regime investigated.