Behaviour of V2O5 — catalyzed CO oxidation in the presence of inert, diluent gases

Abstract A study was conducted on the oxidation of CO over an industrial potassium‐promoted V 2 O 5 catalyst in order to study the influence of He, Ar, Kr, SF 6 and C 4 F 8 diluents on the reaction rate. A differential flow reactor was used between 400° and 440°C with partial pressures of CO 2 , O 2 and diluents varied from approximately 7 to 150 kPa. All the diluents inhibited the reaction rate to varying degrees. Experiments were also performed in which one diluent gas was displaced by another in the reaction mixture. These experiments indicated that the diluents could be arranged in the following increasing order of sorptive interaction with the catalyst: He or Ar < Kr < SF 6 or C 4 F 8 It was concluded that conventional site‐blockage was unable to explain the influence of the diluents. An adsorption interaction between the diluent and the surface complex of the rate limiting step was postulated to explain the inhibition of diluents in CO oxidation and the enhancement of diluents in SO 2 oxidation on the same catalyst.