Synthesis of todorokite-type manganese oxide from Cu-buserite by controlling the pH at atmospheric pressure

• Published in: Microporous and mesoporous materials 2009, Vol.117 (1), p.41-47
• Main Authors: Cui, Haojie, Feng, Xionghan, Tan, Wenfeng, He, Jizheng, Hu, Ronggui, Liu, Fan
• Format: Article
• Language: English
• Subjects: Buserite; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Manganese oxide; Porous materials; Refluxing; Todorokite
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2008.06.006

A todorokite-type manganese oxide molecular sieve material was successfully synthesized at atmospheric pressure by refluxing treatment of Cu 2+ exchanged Na-buserite (named as Cu-OMS-1). TEM (transmission electron microscope) and HRTEM (high resolution transmission electron microscope) images revealed that this material has a needle-phase crystal morphology with thickness 0.1–1 μm, and the lattice fringes spacing 1.0 nm corresponding to the [1 0 0] plane of the todorokite structure. Such morphological and intergrowth characteristics were similar to those of hydrothermally synthesized todorokites. The Cu-OMS-1 with a chemical composition of Cu 0.34MnO 2.19 · 1.11H 2O, was stable below 400 °C. The BET surface area was found to be 62.5 m 2/g, and a major micropore size distribution peak centered at 0.70 nm for Cu-OMS-1 by the Horvath–Kawazoe (HK) method. As determined by the t-plot method, 31% of the surface area was contributed by micropores. The pH of reaction solution plays an important role in the sub-structure modification of formed Cu-buserites and the formation of todorokite at atmospheric pressure. A mechanism for the influence of pH on the transformation is discussed.