Nanometric Colloidal Sols of CeO<sub>2</sub>–ZrO<sub>2</sub> Solid Solution as Catalyst Modifiers. I. Preparation and Structure
作者:Kenji Tanimoto、Hirokazu Kato、Miyuki Hidaka、Satoshi Hinokuma、Keita Ikeue、Masato Machida
DOI:10.1246/bcsj.20130159
日期:2013.10.15
Stable nanometric colloidal sols consisting of fluorite-type metal oxides were prepared for use as chloride-free precursors for automotive catalysts. The aqueous solution containing metal carbonates and tetramethylammonium (TMA) ions was degassed and hydrothermally treated at 140–160 °C. Colloidal suspensions thus formed were purified by ultrafiltration to yield very stable and condensed sol solutions of CeO2 (CE), ZrO2 (ZR) and their solid solutions, CeO2–ZrO2 (CZ), which were stabilized by TMA. Each oxide sol contained 6–8 nm primary particles, but they formed aggregates larger than 40 nm. Local structural analysis by means of XAFS suggested that CZ sol exhibited two types of solid solution domains containing more or less Ce. The dried CZ sol exhibited higher thermal stability and oxygen storage capacity than CE and ZR sols.
制备了由萤石型金属氧化物组成的稳定纳米胶体溶胶,可用作汽车催化剂的无氯化物前体。对含有金属碳酸盐和四甲基铵(TMA)离子的水溶液进行脱气处理,并在 140-160 °C 下进行水热处理。由此形成的胶体悬浮液经超滤提纯后,得到非常稳定的凝聚溶胶溶液,包括 CeO2 (CE)、ZrO2 (ZR) 以及它们的固溶体 CeO2-ZrO2(CZ),这些溶液均由 TMA 稳定。每种氧化物溶胶都含有 6-8 纳米的原生颗粒,但它们形成的聚集体大于 40 纳米。通过 XAFS 进行的局部结构分析表明,CZ 溶胶呈现出两种类型的固溶体畴,其中含有或多或少的铈。与 CE 和 ZR 溶胶相比,干燥的 CZ 溶胶具有更高的热稳定性和储氧能力。