Advanced Pd/Al2O3 three-way catalyst with the modification of CeO2 for passive selective catalytic reduction operation

For TWC used in passive selective catalytic reduction (pSCR) operation, besides the conversion efficiency of CO/ HC/NO, the production of NH3 is also a critical consideration for the evaluation of its catalytic performance. In this work, CeO2 was introduced into Pd/Al2O3 catalyst system, the TWC performance for pSCR operation was studied, and the influence on the physicochemical properties of the catalyst was investigated by a range of techniques. The results reveal that CeO2 can improve the conversion efficiency of CO/HC/NO for Pd/Al2O3 catalyst, and more importantly, the production of NH3 is promoted, the optimal CeO2 content is demonstrated to be 8 wt%. Based on the various characterization results, the promotional effect of CeO2 can be attributed to its ability to promote the dispersion and adjust the chemical state of Pd species, improve the stability of the Al2O3 support, modify the low-temperature reducibility and NH3 desorption property of the catalyst.