Kinetic investigation of the NO reduction by H2 over noble metal based catalysts

This paper reports a kinetic investigation of the overall reduction of NO by H2 over supported palladium based catalysts. Drastic changes in the kinetic features of Pd were found after deposition on reducible LaCoO3 materials in comparison with alumina. Peculiar interactions between palladium and LaCoO3 build up during a pre-activation thermal treatment in H2 at high temperature which completely modify the kinetic behaviour of Pd. In such a case, a classical Langmuir–Hinshelwood mechanism, previously proposed on Pd/Al2O3, is unable to model steady-state rate measurements on pre-reduced Pd/LaCoO3. A bi-functional mechanism involving anionic vacancies at the vicinity of palladium particles leads to a better agreement.