无水硝酸镁制备过程中的水解特性  

Hydrolysis Properties of Anhydrous Magnesium Nitrate during Preparation

作　　者：钟远 袁俊生[1] 王敏[2,3] 王怀有[2,3] 李锦丽 冉广芬[2,3] ZHONG Yuan;YUAN Jun-sheng;WANG Min;WANG Huai-you;LI Jin-li;RAN Guang-fen(School of Chemical Engineering and technology,Hebei University of Technology,Tianjin,300130,China;Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining,810008,China;Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province,Xining,810008,China)

机构地区：[1]河北工业大学化工学院,天津300130 [2]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,青海西宁810008 [3]青海省盐湖资源化学重点实验室,青海西宁810008

出　　处：《盐湖研究》2020年第3期99-108,共10页Journal of Salt Lake Research

基　　金：国家自然科学基金项目(U1707603,U1707601,U1507202);青海省重大科技专项项目(2017-GX-A3)。

摘　　要：在槽式太阳能热发电领域,硝酸镁基熔盐逐渐引起关注。通过六水硝酸镁煅烧法制备无水硝酸镁,采用拉曼、DSC与XRD表征脱水产物,系统研究了环境压力、脱水温度与时间对六水硝酸镁脱水和水解的影响。结果表明,六水硝酸镁在煅烧过程中水解为碱式硝酸镁Mg 3(OH)4(NO 3)2,在水溶液中进一步分解为Mg(OH)2。随着煅烧温度和时间的增加,脱水产物中的含水量逐渐减少,同时水解产物Mg 3(OH)4(NO 3)2含量逐渐增加。真空环境下煅烧,可显著降低硝酸镁的水解反应。六水硝酸镁在真空环境下230℃煅烧1.5 h,所制备的无水硝酸镁中水解产物含量为3.63%。制备的硝酸镁可进一步用于硝酸镁基熔盐的研究。The preparation of magnesium nitrate by dehydrating magnesium nitrate hexahydrate was studied.During the dehydration process of magnesium nitrate hexahydrate,magnesium nitrate is inevitably hydrolyzed.The dehydration products were characterized by Powder X-ray diffraction(XRD),Raman and differential scanning calorimetry(DSC).The content of hydrolysis product was quantitatively analyzed based on its further hydrolysis to magnesium hydroxide in water solution.In order to reduce the hydrolysis of magnesium nitrate,the influence of calcination temperature,calcination time and ambient pressure on dehydration products were evaluated systematically.The results show that magnesium nitrate is hydrolyzed to its basic salt Mg3(OH)4(NO 3)2 when calcining magnesium nitrate hexahydrate in air environment,and the basic salt can be further hydrolyzed to Mg(OH)2.Water contents of dehydration products decrease with calcination time and temperature.In the meantime,the contents of Mg 3(OH)4(NO3)2 in dehydration products increase with calcination temperature and time.Calcining Mg(NO 3)2·6H2O in vacuum is an efficient way to prepare magnesium nitrate with less content of Mg3(OH)4(NO 3)2 compared to in atmospheric environment.The content of Mg3(OH)4(NO 3)2 is as low as 3.63%when Mg(NO 3)2·6H 2 O is calcined at 230℃for 1.5 h in vacuum.Magnesium nitrate prepared and potassium nitrate were mixed and melted,and then mixtures were measured through DSC.These DSC curves of mixtures further confirm the hydrolysis product Mg3(OH)4(NO3)2 and the content of magnesium nitrate.Moreover,these DSC curves show that Mg 3(OH)4(NO3)in magnesium nitrate do not affect the melting point of mixtures.Magnesium nitrate prepared can be used for the study of magnesium nitrate based molten salts.

关 键 词：硝酸镁 水合物 脱水 水解 制备 

分 类 号：TQ11[化学工程—无机化工]