Ethylene combustion on unsupported and supported Pd:a comparative study

摘要

Ethylene combustion is studied at elevated pressures on Pd(100)and compared with supported Pd catalysts.Specific rates of CO2 formation were determined on Pd(100),1 wt%(d_(Pd)= 2.5 nm)and 5 wt%(d_(Pd)= 4.2 nm)Pd/SiO2 catalysts as a function of the O_2/C2H4 ratio over the temperature range 428-473 K.Reaction rates and apparent activation energies on these catalysts are particle size and reactant ratio dependent.The surface carbon concentration on Pd(100)depends on the ratio of the reactants and decreases with increasing O2 pressure.The combustion kinetics is related to the corresponding surface carbon coverage;the highest reaction rate was achieved for relatively low coverage of surface carbon.