Mechanisms of point defect formation and ionic conduction in divalent cation-doped lanthanum oxybromide: first-principles and experimental study.

The ionic conduction mechanism in M-doped (M: Mg, Ca, Zn, and Sr) lanthanum oxybromide (LaOBr) was investigated theoretically and experimentally. Formation energy calculations of point defects revealed that Br ion vacancies and substitutional M ions were the major point defects in M-doped LaOBr, while Br ion vacancies and antisite O ions at Br sites were the major defect types in pure LaOBr. In the relaxed point defect models, doped Mg and Zn ions were displaced from the initial positions of the La ions, and this was experimentally supported by crystal structural analysis.

Environmental catalysts advance focused on lattice oxygen for the decomposition of harmful organic compounds.

The recent industrial growth has made our lives more comfortable; however, it has led to an increase in the concentration of harmful compounds, such as carbon monoxide, volatile organic compounds (e.g., toluene), and phenolic compounds (e.

Dihydroxyacetone production by glycerol oxidation under moderate condition using Pt loaded on LaBiOF solids.

Pt/LaBiOF/SBA-16 (SBA-16: Santa Barbara Amorphous no. 16) catalysts were prepared to produce dihydroxyacetone (DHA) from glycerol under moderate conditions. By using 7 wt% Pt/16 wt% LaBiOF/SBA-16, the DHA yield reached up to 78.

Evidence for enormous iodide anion migration in lanthanum oxyiodide-based solid.

The I ion conduction was demonstrated and quantified in the LaSrZnOI solid. The I ion is considered to be an inferior conductor because of its large ionic size compared to the previously reported conducting ion species. Using modified Tubandt electrolysis, a weight increase at the anodic pellet and a corresponding weight decrease at the cathodic pellet were observed.

Ionic conduction mechanism in Ca-doped lanthanum oxychloride.

The mechanism of ionic conduction in Ca-doped lanthanum oxychloride (LaOCl) was investigated using first-principles calculations based on density functional theory. The calculations of the point defect formation energies suggest that Cl ion vacancies and substituted Ca ions at La sites were dominant point defects. Although the migration energy of an O ion is 0.

Catalytic Liquid-Phase Oxidation of Phenolic Compounds Using Ceria-Zirconia Based Catalysts.

Catalytic liquid-phase oxidation using a catalyst and oxygen gas (Catalytic wet air oxidation, CWAO) is one of the most promising technology to remove hazardous organic compounds in wastewater. Up to now, various heterogeneous catalysts have been reported for phenolic compounds decomposition. The CeO-ZrO based catalysts have been recently studied, because CeO-ZrO works as a promoter which supplies active oxygen species from inside the lattice to the active sites.

Novel Catalysts for Methane Combustion Based on Cobalt-Doped Lanthanum Silicates Having an Apatite-type Structure.

Novel PdO/LaSiCoO/γ-AlO catalysts with applications to methane combustion were developed. These materials were based on the use of LaSiCoO as a promoter because this compound has an oxide-ion conducting apatite-type structure that allows the smooth migration of active oxygen to the PdO activator. Co ions were also introduced into the original LaSiO lattice to enhance its redox properties.

Catalytic liquid-phase oxidation of acetaldehyde to acetic acid over a Pt/CeO2-ZrO2-SnO2/γ-alumina catalyst.

Pt/CeO2-ZrO2-SnO2/γ-Al2O3 catalysts were prepared by co-precipitation and wet impregnation methods for catalytic oxidation of acetaldehyde to acetic acid in water. In the present catalysts, Pt and CeO2-ZrO2-SnO2 were successfully dispersed on the γ-Al2O3 support. Dependences of platinum content and reaction time on the selective oxidation of acetaldehyde to acetic acid were investigated to optimize the reaction conditions for obtaining both high acetaldehyde conversion and highest selectivity to acetic acid.

Carbon monoxide oxidation at room temperature on Pt/CeO2-ZrO2-Bi2O3 catalysts.

A novel Pt/CeO(2)-ZrO(2)-Bi(2)O(3) catalyst was prepared to realize complete CO oxidation at room temperature or below even in the presence of moisture. Using this catalyst, a high CO oxidation activity and a high stability against moisture have been realized simultaneously.

Total oxidation of toluene on Pt/CeO2-ZrO2-Bi2O3/gamma-Al2O3 catalysts prepared in the presence of polyvinyl pyrrolidone.

Pt/CeO(2)-ZrO(2)-Bi(2)O(3)/gamma-Al(2)O(3) (Pt/CZB/Al(2)O(3)) catalysts for the catalytic combustion of toluene, which is one of the volatile organic compounds (VOCs), were prepared by the wet impregnation method in the presence of polyvinyl pyrrolidone (PVP). X-ray powder diffraction, transmission electron microscopy, and BET specific surface area measurement using N(2) adsorption have been used to characterize the catalysts. The catalytic test was conducted from room temperature in a flow of 900 ppm of toluene in air and gas hourly space velocity (GHSV) of 8000 h(-1).

Advanced materials for environmental catalysts.

Recent advances in the synthesis and characterization of materials for environmental catalysts are reported in this paper. Highly advanced environmental catalysts for decomposition of volatile organic compounds and nitrogen oxides were artificially designed based on a concept usually employed in the fields of solid-state chemistry and solid-state ionics. Catalytically active materials for complete ethylene oxidation were prepared by a citrate sol-gel method as a key process to obtain CeO(2)-ZrO(2)-Bi(2)O(3) solid solutions.

A new type of bromide anion conducting solid.

A new type of bromide anion conducting solid electrolyte was designed with the solid electrolyte based on oxybromide; the oxybromide lends unique characteristics of thermal stability and water insolubility (5.6 mg in 100 g of water at 25 degrees C) to the electrolyte which shows the highest Br- anion conductivity reported above 500 degrees C.

A carbon dioxide gas sensor by combination of multivalent cation and anion conductors with a water-insoluble oxycarbonate-based auxiliary electrode.

A compact and inexpensive carbon dioxide gas sensor was successfully realized by the combination of a divalent magnesium ionic conductor of Mg0.7(Zr0.85Nb0.