Synthesis of Monolithic Hierarchically Porous Iron-Based Xerogels from Iron(III) Salts via an Epoxide-Mediated Sol鈥揋el Process

详细信息    查看全文

• 作者：Yasuki Kido ; Kazuki Nakanishi ; Akira Miyasaka ; Kazuyoshi Kanamori
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：June 12, 2012
• 年：2012
• 卷：24
• 期：11
• 页码：2071-2077
• 全文大小：517K
• 年卷期：v.24,no.11(June 12, 2012)
• ISSN：1520-5002

文摘

Various iron-based polycrystalline monoliths, Fe₃O₄, iron, and Fe₃C, with hierarchically distributed pores have been synthesized from ionic precursors using a sol鈥揼el process accompanied by phase separation. Propylene oxide acts as a proton scavenger to increase pH moderately and uniformly in a reaction solution, which leads to homogeneous gelation. On the other hand, poly(acrylamide) works as a phase separation inducer as well as a precipitation inhibitor. Appropriate choice of iron precursor, solvent, polymer, and epoxide allowed the formation of iron(III)-based xerogels with cocontinuous macroporous structures. The dried gels were amorphous, whereas heating in air above 300 掳C led to the formation of 伪-Fe₂O₃. Calcination under an inert condition above 400 掳C formed Fe₃O₄, iron, and Fe₃C without collapse of macrostructures. Examination has been carried out using SEM, TG-DTA, FT-IR, Hg intrusion, pH measurement, X-ray diffraction, and N₂ adsorption鈥揹esorption.

Keywords:

iron hydroxide; iron oxide; iron carbide; xerogel; monoliths; hierarchically porous; sol鈭抔el; propylene oxide; phase separation