CTAをテンプレートとするオキシ硫酸プラセオジム酸素吸蔵物質の低温合成(<特集>希土類系物質の精密合成,形態制御および機能物性)

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Porous praseodymium oxysulfate, Pr_2O_2SO_4, with a large oxygen storage capacity was prepared from precipitates, which were formed by adding (NH_4)_2SO_4 to a mixed aqueous solution of Pr(NO_3)_3 and cationic surfactant, CTA (cetyltrimethyl ammonium ion). Heating the precipitate, Pr-SO_4-CTA, yielded directly the single phase of Pr_2O_2SO_4 at a low temperature of 300℃, compared to≥800℃ required for the decomposition of Pr_2(SO_4)_3 (Pr-SO_4), and compared to≥500℃ required for the mesophase of Pr and dodecyl sulfate (Pr-DS) in our previous study.^<1)> The effect of preparation route on microstructure and oxygen release/storage property of Pr_2O_2SO_4 was studied by using XRD, TG, SEM, N_2 adsorption and catalytic reaction. In contrast to the macropores (≥30 nm in size, 8 m^2 g^<-1>) of Pr-SO_4 and mesopores (≤10 nm, 28 m^2 g^<-1>) of Pr-DS, Pr-SO_4-CTA showed a wide pore size distribution in the range 2-40 nm and a larger surface area of 37 m^2 g^<-1>. The porous structure is very effective in increasing the rate of oxygen release as well as storage. The anaerobic CO oxidation of 1 mass% Pd-loaded Pr_2O_2SO_4 was evaluated in CO/O_2 cycled feed stream reactions. It was found that the catalyst prepared from Pr-SO_4-CTA achieved the highest catalytic activity due to the high porosity and specific surface area.
社団法人日本セラミックス協会の論文
2007-10-01