Preparation of Lamellar Mg(OH)2 with Caustic Calcined Magnesia through Apparent Hydration of MgO

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• 作者：Hongfan Guo ; Jiayang Xie ; Han Hu ; Xue Li ; Tianbo Fan ; He Nan ; Yunyi Liu
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2013
• 出版时间：September 25, 2013
• 年：2013
• 卷：52
• 期：38
• 页码：13661-13668
• 全文大小：431K
• 年卷期：v.52,no.38(September 25, 2013)
• ISSN：1520-5045

文摘

A process using plentiful and inexpensive caustic calcined magnesia (CCM; main component is MgO) to prepare lamellar MH of high purity is described. The process begins with the reaction of MgO in CCM with NH₄NO₃ at 100 掳C to produce ammonia gas and Mg(NO₃)₂ solution and the subsequent filtration of Mg(NO₃)₂ solution to remove impurities (e.g., SiO₂). Then, the obtained ammonia is introduced into the Mg(NO₃)₂ solution to produce MH precipitate and NH₄NO₃. After the MH precipitate is separated by filtration, the filtrate containing NH₄NO₃ is returned to the initial step. The overall reaction of this process is the hydration of MgO to MH. Therefore, this process is called the apparent-hydration method. This apparent-hydration method overcomes the disadvantages of the true hydration method, such as the inability to remove impurities. A crucial finding is that, because of the presence of trace SO₄^{2鈥?/sup> in the obtained Mg(NO₃)₂ solution, a MH product with a narrow particle size distribution cannot be produced. After removal of the SO₄2鈥?/sup> with Ba(NO₃)₂, lamellar MH with a narrow particle size distribution can be synthesized at 120 掳C in one step. This work provides a promising route to the use of CCM to prepare MH.}