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尿素法合成高结晶度类水滑石
引用本文:杨飘萍,宿美平,杨胥微,刘国宗,于剑锋,吴通好,赵得熙,张泰善,李东求.尿素法合成高结晶度类水滑石[J].无机化学学报,2003,19(5):485-490.
作者姓名:杨飘萍  宿美平  杨胥微  刘国宗  于剑锋  吴通好  赵得熙  张泰善  李东求
作者单位:1. 吉林大学化学系,长春,130023
2. 韩国化学研究所,韩国大田,305-343
摘    要:尿素的高温分解特性被用于控制层状化合物合成过程中的pH值。室温下尿素可与硝酸盐形成均一溶液,当其高温分解时可以保证溶液内部各点的pH值始终一致,因而可获得高结晶度的水滑石样品。利用该法可合成出Mg-Al、Zn-Al及Ni-Al类水滑石,但难以合成出Co-Al,Mn-Al及Co-Cr类水滑石,相信这与不同金属离子发生沉淀时所需的pH值有关。

关 键 词:尿素分解  pH值控制  水滑石
修稿时间:2002年11月25

Synthesis of High Crystallinity Hydrotalcite-like Compounds with Urea Method
YANG Piao-Ping,SU Mei-Ping,YANG Xu-Wei,LIU Guo-Zong,YU Jian-Feng,WU Tong-Hao,CHO Deug-Hee,CHANG Tae-Sung and LEE Dong-Koo.Synthesis of High Crystallinity Hydrotalcite-like Compounds with Urea Method[J].Chinese Journal of Inorganic Chemistry,2003,19(5):485-490.
Authors:YANG Piao-Ping  SU Mei-Ping  YANG Xu-Wei  LIU Guo-Zong  YU Jian-Feng  WU Tong-Hao  CHO Deug-Hee  CHANG Tae-Sung and LEE Dong-Koo
Abstract:Three methods, titration coprecipitation, anionic exchange and thermal decomposition reconstitution methods, have been so far used for the synthesis of the anionic clay, respectively. However, the titration coprecipitation method includes low supersaturation and high supersaturation processes. But the common drawback of the method is that the instantaneous pH value is certainly different in every part of the slurry no matter how to increase the stirring speed. Although it is easier to crystallize in the low supersaturaion condition, which usually gives rise to precipitation, than in the supersaturation condition that the rate of nucleation is higher than that of crystal growth, it is still difficult to obtain the hydrotalcites with high crystallinity. In order to overcome this shortcoming brought by titration coprecipitation process, urea decomposition homogeneous coprecipitation was investigated in synthesis of hydrotalcite like compounds. The decomposing property of urea in high temperature has been used to control the pH value in the synthesizing process. Urea, blended with metal nitrate, forms a kind of homogeneous solution in ambient temperature. Furthermore, when it decomposes in high temperature, the pH value is the same in everywhere in the solution. Therefore, hydrotalcite like compounds with high crystallinity can be achieved. Making use of this method can synthesize the hydrotalcite like compounds of Mg Al, Zn Al and Ni Al. However, it is difficult to synthesize the Co Al, Mn Al and Co Cr hydrotalcite like compounds. The cause is certain to correlate the pH value in the process of precipitation.
Keywords:urea decomposition  control of pH value  hydrotalcite
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