Advanced materials for environmental catalysts

Abstract

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. On the other hand, direct NO decomposition catalysts were designed and prepared focusing on the open spaces and oxide anion vacancies in the crystal lattice. Evaluation of the materials as environmental catalysts demonstrated significant advantages over the conventional ones. The design strategy, synthetic method, and structural features of these concerto catalysts are addressed.

Complete Toluene Oxidation on Pt/CeO2-ZrO2-ZnO Catalysts

“…In our previous studies, furthermore, we found that employing such solid solutions, which have high oxygen release and storage properties, as promoters was effective to establish complete oxidation of VOCs at moderate temperatures [16][17][18]. In particular, introduction of a small amount of SnO 2 , which has been well-known as a typical n-type semiconductor with electronic conduction [20], into the CeO 2 -ZrO 2 lattice considerably facilitated the VOCs oxidation [19].…”

“…In particular, some active platinum catalysts supported on them have been reported for VOCs oxidation [11][12][13][14][15][16][17][18][19]. CeO 2 and CeO 2 -ZrO 2 solid solutions can release and store oxygen corresponding to the surrounding atmosphere, and these properties make them attractive components as promoters of the automotive exhaust three-way catalysts [11].…”

Selective liquid phase oxidation of cyclohexane over Pt/CeO2-ZrO2-SnO2/SiO2 catalysts with molecular oxygen

“…We have previously prepared novel catalysts to realize the complete oxidation of volatile organic compounds under moderate conditions [10,11]. These catalysts involved a combination of platinum and a solid promoter to supply reactive oxygen molecules, which was important in order to allow oxidation of hydrocarbons in the gas phase [11,12].…”

The electron structure and photocatalytic activity of Ti(IV) doped Bi2O3

“…There are tetragonal structure () and body-centered cubic structure () of the metastable form compounds at 650 °C. All of the four forms exhibited highly photocatalytic activity [5][6][7][8]. However, the lack of light absorption in the visible light region hindered their use as photocatalysts in the environmental application.…”