Mesoporous ceria

Mesoporous oxides have been fabricated using a variety of methods spanning templated self-assembly of nanoparticles, nanocasting and using surfactants to act as a molecular scaffold to help build the mesoporous architecture. Template-free self-assembly of nanoparticles via ice crystallisation has also been achieved, where the phase change from water to ice sculpts the nanoparticles into 

Similar to simulating the self-assembly of ceria nanoparticles into nanochains (ID assembly), the nanoparticles can also be assembled into nanosheets (2D assembly) and framework architectures (3D assembly). In particular. Fig. 5.16 shows spherical Ti-Ce02 core-shell nanoparticles assembled in three dimensions to form mesoporous architectures. Under MD simulations the nanoparticles attach and agglomerate together to form the walls of the mesoporous 

1 Systematic enumeration of nanostructure generating mesoporous models 

The final models thus have various hierarchical levels of structural complexity (Fig. 5.18). They include the architecture of the mesoporous material, the presence of microstructural features 

17 Procedure for generating atomistic models for mesoporous materials by positioning nanoparticles at crystallographic positions. The images at the bottom are atomistic models of mesoporous MgO generated by positioning MgO nanoparticles at FCC positions. Reprinted with permission from Sayle et al. Copyright 2008 American Chemical Society. 

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P Ratnasamy, Crystalline, mesoporous ceria—zirconia based reforming catalysts for PEM fuel cells. Preprints Symp.—Am. Chem. Soc., Div. Fuel Chem. 46,635—640 (2001). 

Mesoporous ceria—zirconia nanostructures could be obtained through evaporation induced self assembly process (Yuan et al. 2007 Figure 8). Such ordered nanostructures may show promising applications in catalysis and sensors with special selectivities. 

Mesoporous ceria and ceria-zirconia powders with high surface area have also been prepared using a surfactant-assisted method to prepare catalysts containing Ce02... 

Figure 1. XRD patterns of mesoporous ceria samples from gel composition (a) 134 Ce 2230 propanol 1 F-127 (b)...

Similarly, mesoporous high surface area (350 to 370m /g) ceria-titania mixed metal oxide showed greater efficacy for removal of toluene at room temperature compared to the corresponding nonporous mixed metal oxide or the mesoporous titania or ceria (107). Interestingly, the toluene removal ability almost doubled after Pt impregnation into the base mesoporous ceria-titania. 

Suzuki and Sinha have prepared novel bimodal mesoporous crystalline ceria nanoparticles and evaluated their performance in VOC removal (106). The mesoporous ceria showed 92% acetaldehyde removal with 33% CO2 conversion at ambient temperature after 24 h. This acetaldehyde removal performance is nearly twice as high as that for conventional VOC removal using materials such as activated carbon or mesoporous silica. 

Idakiev et al. [137] reported mesoporous ceria and nanorods Ce02 for the Au catalysts for WGSR. Both mesoporous- and nanorod-supported catalysts exhibit higher activity than regular Au/Ce02. Of the mesoporous- and nanorod-supported catalysts, mesoporous-supported catalyst exhibited higher activity. 

Preparation of Mesoporous Ceria in the Presence of Non-Aqueous Phases... 

In this paper we present the use of aniline in methanol solution as the precipitating agent in the synthesis of mesoporous ceria. Different reaction conditions were used including elevated temperature and ageing time, whereas the use of a templating matrix was also examined. 

Preparation of mesoporous ceria in the presence of non-aqueous phases... 

Figure 5.16 Assembly of ceria nanoparticles into mesoporous architectures. Top Schematic illustrating the principle. Bottom Atomistic model of the mesoporous ceria, which is enlarged (bottom right) to reveal the 111 and 100 planes exposed at the internal surfaces of the material. Reprinted with permission from Sayle et Copyright 2007 American Chemical Society.

Figure 6.8 TEM images of mesoporous Ce02. (a) Uncalcined ceria-surfactant composite, (b) Mesoporous ceria after calcination at 673 Kin air. (c) Mesoporous ceria calcined in air at 873 K. Reprinted with permission from Lyons et Copyright 2002 the Royal Chemical Society.

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