Kinetic modeling of the reoxidation of vanadia-based catalysts

The reoxidation kinetics of classical vanadia-based EL10V Eurocat catalysts are compared with those obtained on a new catalytic material, prepared by DC magnetron sputtering, by means of temporal analysis of products (TAP) at reduction and reoxidation temperatures from 723 to 823 K. After reduction to different degrees of reduction with multipulses of propane, the kinetics of reoxidation were obtained from single-pulse experiments. Irreversible dissociative chemisorption of di-oxygen allowed to describe the latter over the full range of investigated conditions for EL10V1 with a single pre-exponential factor, A = 4.05 × 102 kgVm3/mol2 s, and a single activation energy, Ea = 33.41 kJ/mol. In the case of the sputtered catalysts, investigated at 773 K only, a single rate coefficient also describes the reoxidation at different degrees of reduction for every V-loading. Its value increases with increasing V-loading up to a constant value of 1.09 ± 0.11 kgVm3/mol2 s, but remains lower than the corresponding rate coefficient for the reoxidation for EL10V8 which amounts to 13.30 kgVm3/mol2 s.