Effect of Rare Earth Additives on the Catalytic Performance of Rh/ZrO2 Three-Way Catalyst

Abstract

The catalytic activity of Rh/ZrO 2 for NO-CO-C 3 H 6 -O 2 reaction under stoichiometric conditions was significantly improved by addition of rare earth. Among the catalysts tested here, Y-doped Rh/ZrO 2 (Rh/Y/ZrO 2 ) showed the highest three-way catalytic performance. The catalytic activity of rare earth-doped Rh/ZrO 2 was strongly related to the Rh dispersion, which was improved by using rare earth-doped ZrO 2 with large amount of surface basic sites. The role of rare earth additive was considered to control the surface basicity of ZrO 2 and stabilize the Rh species in high dispersion state. Y-stabilized ZrO 2 was found to be effective support for Rh catalyst in NO-CO-C 3 H 6 -O 2 reaction. The site geometry and the surface electric state of Rh can be altered by interacting with Y 2 O 3 , leading us to consideration that the presence of suitable Rh-Y 2 O 3 interaction is responsible for high NO reduction activity of Rh/Y-ZrO 2 .

Recent advances in gasoline three-way catalyst formulation: A review

“…Zirconia-based oxides can be used to support Rh particles to avoid unfavorable interactions between Rh and ceria. Haneda et al 39,40 examined the use of 5 mol% doped ZrO 2 as a support for a Rh catalyst. La, Pr, Nd, Y, Ce, Sm, Gd, Tb, and Dy were chosen as potential dopants.…”

Relationship between design strategies of commercial three-way monolithic catalysts and their performances in realistic conditions

“…Usually, metals are supported on a washcoat containing a mixture of (i) cerium-zirconium based oxides primarily due to their oxygen storage capacity (OSC) and resistance to thermal sintering [7][8][9][10][11], and (ii) γ-alumina for its high surface area and thermal stability [12,13]. Numerous rare earth and alkaline promoter materials such as La, Nd, Pr, Sm, Y, Ba or Sr can be added to the washcoat to further improve thermal stability and OSC performances [13][14][15][16][17]. Monolithshaped cordierite substrates with hexagonal or square channels are largely used to support the metal/washcoat catalysts to ensure merely hydrodynamics limiting the back-pressure and improve mass transfer and thermal/mechanical stability [18].…”

Effects of Doping Rare Earth Elements (Y, La, and Ce) on Catalytic Performances of CoMo/MgAlM for Water Gas Shift Reaction

“…Reasonably, the catalytic performance is the synergistic effect of the metal dispersion and the extent of sulfidation behavior of the oxidic species in CoMo-based WGSR catalysts, and the effect is affected by the good surface basicity of MgAl supports. ,, Up to now, the reports about CoMo modified MgAl show relatively good catalytic activities, and adjusting of basic sites via the decoration of MgAl supports is a good way to further improve their activities in the WGSR. A variety of basic oxide supports, especially for rare earth compounds such as La 2 O 3 , CeO 2 , and Y 2 O 3 , were reported to possess high base strength. − Reasonably, LDHs modified with rare earth elements were prepared to improve their calcined product basicity. − For instance, La modified anionic hydrotalcite of La/MgAlO-mixed oxide catalysts exhibit much improved catalytic activities in the transesterification reaction of 1-phenylethanol with diethyl carbonate because of their enhanced base strength . Moreover, the engineering of basic properties in the MgAl-LDHs strongly affects their catalytic activities for the cyanoethylation of ethanol with acrylonitrile, which were also proved to be good and air stable in the cyanoethylation reaction .…”