A series of Pt-Pd bimetallic catalysts supported on CeO_(2)-ZrO_(2)-La_(2)O_(3) mixed oxides were synthesized through the conventional impregnation method.Three-way catalytic performance evaluations along with detaile...A series of Pt-Pd bimetallic catalysts supported on CeO_(2)-ZrO_(2)-La_(2)O_(3) mixed oxides were synthesized through the conventional impregnation method.Three-way catalytic performance evaluations along with detailed physio-chemical characterizations were carried out to establish possible structure-activity correlations.Results show that on the one hand,different Pt/Pd ratios can strongly affect the TWC behaviors of Pt-Pd/CZL catalysts by modulating the synergistic effect between Pt and Pd.On the other hand,higher Pt/Pd ratio also favors better dispersion of precious metals.Such improved precious metals(PM)dispersion can promote the metal-support interaction and increase the surface oxygen vacancies concentration,thereby raising the dynamic oxygen storage/release capacity,improving the redox ability as well as enha ncing the thermal stability of the Pt-Pd/CZL catalyst.Moreover,the stro ng metal-support interaction can augment surface oxygen vacancy concentration,thereby benefiting low temperature CO and NO reaction via augmented NOxadsorption and nitrate conversion.展开更多
FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen tempe...FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen temperature-programmed reduction （H2-TPR） techniques. The dynamic oxygen storage capacity （DOSC） was investigated by mass spectrometry with CO/O2 transient pulses. The powder XRD data following Rietveld refinement revealed that the solubility limit of iron oxides in the CeO2 was 5 mol% based on Fe/（Ce＋Fe）. The lattice parameters experienced a decrease followed by an increase due to the influence of the maximum solubility limit of iron oxides in the CeO2. TPR analysis revealed that Fe introduction into ceria strongly modified the textual and structural properties, which influenced the oxygen handling properties. DOSC results revealed that Ce-based materials containing Fe oxides with multiple valences contribute to the majority of DOSC. The kinetic analysis indicated that the calculated apparent kinetic parameters obey the compensation effect. The three-way catalytic performance for Pd-only catalysts based on the Fe doping support exhibited the redundant iron species separated out of the CeO2 and interacted with the ceria and Pd species on the surface, which seriously influenced the catalytic properties, especially after hydrothermal aging treatment.展开更多
基金Project supported by the Key Program of Science Technology Department of Zhejiang Province(2018C03037)the Natural Science Foundation of Jiangsu Province(BK20201037)+2 种基金Jiangsu Industry-University-Research Cooperation Project(BY2022101)the Scientific Research Fund of Nanjing Institute of Technology(YKJ2019111)Students'Science and Technology Innovation Fund of Nanjing Institute of Technology(TB202312034).
文摘A series of Pt-Pd bimetallic catalysts supported on CeO_(2)-ZrO_(2)-La_(2)O_(3) mixed oxides were synthesized through the conventional impregnation method.Three-way catalytic performance evaluations along with detailed physio-chemical characterizations were carried out to establish possible structure-activity correlations.Results show that on the one hand,different Pt/Pd ratios can strongly affect the TWC behaviors of Pt-Pd/CZL catalysts by modulating the synergistic effect between Pt and Pd.On the other hand,higher Pt/Pd ratio also favors better dispersion of precious metals.Such improved precious metals(PM)dispersion can promote the metal-support interaction and increase the surface oxygen vacancies concentration,thereby raising the dynamic oxygen storage/release capacity,improving the redox ability as well as enha ncing the thermal stability of the Pt-Pd/CZL catalyst.Moreover,the stro ng metal-support interaction can augment surface oxygen vacancy concentration,thereby benefiting low temperature CO and NO reaction via augmented NOxadsorption and nitrate conversion.
基金support the National HighTech Research and Development Program of China (No.2011AA03A405)
文摘FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen temperature-programmed reduction （H2-TPR） techniques. The dynamic oxygen storage capacity （DOSC） was investigated by mass spectrometry with CO/O2 transient pulses. The powder XRD data following Rietveld refinement revealed that the solubility limit of iron oxides in the CeO2 was 5 mol% based on Fe/（Ce＋Fe）. The lattice parameters experienced a decrease followed by an increase due to the influence of the maximum solubility limit of iron oxides in the CeO2. TPR analysis revealed that Fe introduction into ceria strongly modified the textual and structural properties, which influenced the oxygen handling properties. DOSC results revealed that Ce-based materials containing Fe oxides with multiple valences contribute to the majority of DOSC. The kinetic analysis indicated that the calculated apparent kinetic parameters obey the compensation effect. The three-way catalytic performance for Pd-only catalysts based on the Fe doping support exhibited the redundant iron species separated out of the CeO2 and interacted with the ceria and Pd species on the surface, which seriously influenced the catalytic properties, especially after hydrothermal aging treatment.
