Abstract
For three-way catalysts (TWC) applied in lean burn gasoline engines for passive selective catalytic reduction (pSCR) operation, besides the conversion efficiency of HC/CO/NO, the production of NH3 is also an important concern. In this work, La2O3 was introduced into the Pd/Al2O3 catalyst system, the influence on its TWC performance for pSCR operation was investigated, and the physicochemical properties were characterized by a range of techniques. The results reveal that the introduced La2O3 mainly interacts with Al2O3 by preferentially anchoring to the tetra-coordinated Al sites on the surface. When the catalyst is modified by appropriate amount of La2O3 (4 wt%), higher dispersion of Pd species, larger amount of Pd2+ and active oxygen species are achieved, which well contributes to improved low-temperature reduction ability and NH3 desorption property of the catalyst. As a consequence, excellent catalytic conversions of HC/CO/NO are obtained, and meanwhile, higher concentration of NH3 is generated, making the modified catalyst more promising for pSCR operation.
Published Version
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