Synthesis of an Advanced Pd–Rh Bimetallic Three-Way Catalyst for Gasoline Engine Emission Control with the Assistance of Citric Acid

Abstract: Citric acid was introduced into the Pd–Rh bimetallic catalyst system to achieve advanced three-way catalytic performance. The characterization results reveal that compared with bare Pd–Rh catalyst, the introduction of appropriate amount of citric acid could help increase the dispersion of Pd and Rh species on Al2O3, and meanwhile, improved hydrothermal stability is obtained. However, when excessive amount of citric acid is introduced, it may compete with Pd and Rh for the surface sites of Al2O3, which would conversely bring about negative influence on the dispersion and hydrothermal stability of the catalyst. As a consequence, after hydrothermal aging treatment, higher dispersion and more active oxidation states of Pd and Rh species are maintained, and consequently, modified reduction capability and enhanced three-way catalytic performance could be achieved for the modified Pd–Rh catalyst, and the optimal amount of citric acid is demonstrated to be 2 wt %.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology