title: Acidic amorphous silica prepared from iron oxide of bacterial origin.
abstract: Microporous and mesoporous silica derived from biogenous iron oxide is an attractive catalyst for various organic reactions. Biogenous iron oxide contains structural silicon, and amorphous silica remains after iron oxide is dissolved in concentrated hydrochloric acid. The amorphous silica containing slight amounts of iron (Si/Fe = ∼150) is composed of ∼6-nm-diameter granular particles. The amorphous silica has a large surface area of 540 m(2)/g with micropores (1.4 nm) and mesopores (<3 nm). By using pyridine vapor as a probe molecule to evaluate the active sites in the amorphous silica, it was found that this material has strong Brønsted and Lewis acid sites. When the catalytic performance of this material was evaluated for reactions including the ring opening of epoxides and Friedel-Crafts-type alkylations, which are known to be catalyzed by acid catalysts, this material showed yields higher than those obtained with common silica materials.
authors: Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors: Hideki
authors: H
authors: Hashimoto
authors: Atsushi
authors: A
authors: Itadani
authors: Takayuki
authors: T
authors: Kudoh
authors: Yasushige
authors: Y
authors: Kuroda
authors: Masaharu
authors: M
authors: Seno
authors: Yoshihiro
authors: Y
authors: Kusano
authors: Yasunori
authors: Y
authors: Ikeda
authors: Makoto
authors: M
authors: Nakanishi
authors: Tatsuo
authors: T
authors: Fujii
authors: Jun
authors: J
authors: Takada
mesh_terms: D002384:Catalysis; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism*; D042743:Leptothrix / Q000378:metabolism*; D010084:Oxidation-Reduction; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D012822:Silicon Dioxide