FEASIBILITY STUDY TOWARDS A CU K/MO(CL) SOOT OXIDATION CATALYST FOR APPLICATION IN DIESEL EXHAUST-GASES/

The activity of a supported catalyst containing copper, potassium and molybdenum was studied. Model experiments revealed that chlorine plays an essential role in the activity of this catalyst. It was shown that the active species of the catalyst probably consist of copper chlorid e compounds. Deactivation of the catalyst was studied, and was found t o be more pronounced for a poor contact between soot and catalyst comp ared with a tight contact. Deactivation rates were found to be low, wh ich was tentatively suggested to be caused by loss of active species t hat are formed by solid-solid reactions (e.g. KCl + CuMoO4 --> K-molyb dates + Cu-(oxy)chlorides) which are slow as a result of low solid-sta te diffusion rates. A Cu/K/Mo-catalyst as a coating on small segments of a wall flow monolith downstream of a diesel engine showed a relativ ely low activity. Besides, the catalyst was found to deactivate rather fast, which corroborated the outcome of the above mentioned model stu dy. As a result, the feasibility of this Cu/K/Mo-catalyst for use in p ractical applications is low due to a progressive loss of catalytic ma terial by high vapour pressures of active components formed by solid-s olid reactions of less volatile compounds present in the catalyst.