Causes of deactivation and an effort to regenerate a commercial spent three-way catalyst

摘要

The main aim of the present paper is to summarize the research work of our group with respect to the deactivation and regeneration of the three-way automotive catalysts (T.W.C.). Measurements describing the effect of the thermal deactivation and contaminants accumulation on the structure and the efficiency of an a vehicle aged T.W.C. are presented. A variety of techniques, such as SEM-EDS, XRD, CTEM, ICP-AES, ICP-MS and AAS, were applied in this effort. Since, thermal deactivation is more or less irreversible, special attention was given to the nature and the distribution of the contaminants accumulated on the T.W.C. active surface. Based on these observations, a leaching procedure with acetic acid was tested and optimized in laboratory scale for the removal of the contaminants. The leached samples of the T.W.C. were examined with respect to their catalytic activity (CO and C_2H_4 oxidation, NO reduction and N_2 production). The leaching procedure seems to improve considerably the catalytic activity of the aged catalyst.