热重分析
煅烧
镍
水镁石
水滑石
差热分析
材料科学
无定形固体
层状双氢氧化物
非阻塞I/O
无机化学
尖晶石
比表面积
共沉淀
化学工程
化学
氢氧化物
冶金
镁
衍射
结晶学
催化作用
生物化学
物理
光学
工程类
作者
R.J. Ruano-Casero,M.E. Pérez-Bernal,V. Rives
标识
DOI:10.1002/zaac.200570031
摘要
Abstract A constant pH precipitation method has been applied to obtain solids with Ni/Fe molar ratios of 2/1, 3/2, 1/1, 2/3, and 1/2. In all cases, a phase with the hydrotalcite‐like structure is obtained, containing Ni II and Fe III in the brucite‐like layers and carbonate in the interlayer, and, for samples with a Ni/Fe molar ratio lower than 2/1, amorphous hydrated iron oxides, undetected by X‐ray diffraction, are also formed. The solids have been characterized by element chemical analysis, powder X‐ray diffraction, differential thermal analysis, thermogravimetric and differential thermogravimetric analysis, FT‐IR spectroscopy, temperature‐programmed reduction and assessment of specific surface area by nitrogen adsorption at −196 °C. In all cases reduction leads to zero‐valent state for the metals, reduced nickel particles probably favouring reduction of Fe III species; the specific surface area increases with the iron content, probably due to the amorphous nature of the hydrated iron oxides formed. Calcination at 1200 °C in air leads to well crystallized solids, formed by NiFe 2 O 4 spinel and, additionally, rocksalt‐type NiO for Ni/Fe ratios larger than 1/2. In this way, solids with tailored compositions of these two phases can be prepared.
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