Synthesis and Characterization of Nanometer Ce 0.75 Zr 0.25 O 2 Powders by Solid-State Chemical Reaction Method

Liu

Advances in Applied Ceramics

et al. 2017

CeO 2 -ZrO 2 solid solution was synthesised by mechanical activation solid-state chemical reaction method and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal dilatometer, Hebb-Wagner method and DC van der Pauw method. The effects of CeO 2 content on the crystal structure, microstructure, thermal expansion coefficient (TEC), electronic conductivity and total conductivity were investigated. XRD analysis showed that (25 and 75 mol-%) CeO 2 -ZrO 2 solid solutions corresponded to tetragonal and cubic phase, and 50 mol-% CeO 2 -ZrO 2 belonged to the mixture of tetragonal and cubic phases. SEM analysis showed that doping CeO 2 was helpful to the sinterability of CeO 2 -ZrO 2 samples. The TECs increased from 13.27 × 10 −6 to 14.72 × 10 −6 K −1 with increasing CeO 2 content. The electronic and total conductivities of 75 mol-% CeO 2 -ZrO 2 were largest, reaching 1.02 × 10 −4 S cm −1 and 1.02 × 10 −2 S cm −1 at 850°C, respectively.

Section: Introductionmentioning

confidence: 99%

Crystal structure, microstructure, thermal expansion and electrical conductivity of CeO₂–ZrO₂ solid solution

Liu

Advances in Applied Ceramics

et al. 2017

“…Often, a liquid component is added to the mill. For example, Zheng et al [155], starting from ZrOCl 2 •2H 2 O, Ce 2 (CO 3 ) 3 and H 2 C 2 O 4 •2H 2 O, added various surfactants to ground substrates. The largest specific surface areas (>80 m 2 /g) of Zr x Ce 1−x O 2−y nanoparticles were obtained using neutral surfactants and these carriers were the best for the subsequent deposition-precipitation of Pd and Rh in the production of TWC car catalysts.…”

Section: Synthesis Of the Ceria-based Nanoparticlesmentioning

confidence: 99%

Synthesis and Specific Properties of the Ceria and Ceria-Zirconia Nanocrystals and Their Aggregates Showing Outstanding Catalytic Activity in Redox Reactions—A Review

Dziembaj,

Molenda,

Chmielarz

2023

Catalysts

Non-stoichiometric CeO2−y, especially in the form of nanocrystal aggregates, exhibits exceptional catalytic activity in redox reactions. It significantly improves the activity of transition metals and their oxides dispersed on/or in it, also acting as an oxygen buffer. Particularly, active oxygen species (O2n−, O−) are generated at the M/CeO2−y nanoparticle interface, as well as in the surface layer of their solid-state solutions MxCe1−xO2−y. The crystal structure of CeO2, ZrO2 and (Ce, Zr)O2 and its defects are discussed in connection with the resulting specific catalytic activity. All the methods (simple precipitation and co-precipitation from mother liquors, sol–gel methods, precipitation from nanoemulsions, hydrothermal and solvothermal techniques, combustion and flame spray pyrolysis, precipitation using molecular and solid-state matrices, 3D printing and mechanochemical methods) used for the synthesis of these nanomaterials are comprehensively reviewed, describing the rules of individual procedures and preparation details. Methods of deposition of metal catalysts and their oxides on CeO2 nanoparticles, such as impregnation, washcoating and precipitation deposition, were also discussed. This review contains more than 160 references to representative papers wherein the reader can find further details on individual syntheses of effective ceria-based catalysts for redox reactions.

“…11 Trasobares et al reported that zirconia−ceria mixed oxide nanomaterials are of interest as catalysts in a variety of chemical transformations in the area of environmental protection. 17 The synthesis and characterization of nanometer Ce 0.75 Zr 0.25 O 2 powders by a solid-state chemical reaction method was reported by Zheng et al 18 However, there have been no reports on the use of phosphomolybdic acid supported on ZrO 2 −CeO 2 as the catalyst for the solvent-free oxidation of benzyl alcohol. The present article reports for the first time the surface and textural characterization of phosphomolybdic acid stabilized zirconia−ceria mixed oxide.…”

Section: Introductionmentioning

confidence: 99%

Facile Method for the Synthesis of Phosphomolybdic Acid Supported on Zirconia–Ceria Mixed Oxide and Its Catalytic Evaluation in the Solvent-Free Oxidation of Benzyl Alcohol

Mallick

Rana

Parida

2012

Ind. Eng. Chem. Res.

A series of phosphomolybdic acid (5−20 wt % PMA) promoted zirconia−ceria (ZrO 2 −CeO 2 ) mixed oxides were synthesized by an impregnation method and characterized by XRD, nitrogen adsorption/desorption, UV−vis DR spectroscopy, TPR/TPD, and 31 P MAS NMR spectroscopy. NMR spectra revealed that the catalyst retained the Keggin structure of PMA even after calcination at 500 °C. The catalysts were screened for the solvent-free liquid-phase oxidation of benzyl alcohols using hydrogen peroxide as the oxidizing agent. The sample of 15 wt % PMA/ZrO 2 −CeO 2 showed 85% conversion and 96% selectivity to the corresponding aldehydes.