六水草酸镝热分解过程机理及动力学研究
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摘要
稀土草酸盐是目前制备稀土氧化物,尤其是制备具有可控粒度的稀土氧化物常用的前驱体,它具有沉淀物晶型好,易于过滤分解等优点.然而,目前稀土草酸盐热分解的动力学研究较少,因此,采用热重-差热分析法,研究六水草酸镝的热分解过程,通过Kissinger、Ozawa和Crane法计算六水草酸镝的分解动力学参数,通过Coats-Redfern法求出反应的机理函数.结果表明:几种方法计算的分解活化能比较接近,六水草酸镝热分解分2步进行,第1步为1级脱水反应,反应机理函数为F1,表观活化能为62.48 k J/mol,指前因子为1.84×106;第2步也为1级分解反应,反应机理函数为F2,表观活化能为106.42 k J/mol,指前因子为2.79×107.
Rare earth oxalates are the common precursors for preparing rare earth oxides, especially rare earth oxides with controlled particle size, which have the advantages of good precipitate crystal form, easy filtration and decomposition, etc. However, kinetic study of the thermal decompositionforcurrent rare earth oxalates was less,Therefore,thethermogravimetry-differential thermal analysis method was used to study the thermal decomposition process of dysprosium hexahydrate. The decomposition kinetics parameters of dysprosium hexahydrate were calculated by Kissinger, Ozawa and Crane methods. Coats-Redfern method was used to find the mechanism function of the reaction.The results showed that the decomposition activation energies calculated by several methods were quite close and the thermal decomposition of dysprosium hexahydrate was carried out in two steps. The first step was the first order dehydration reaction. The reaction mechanism function was F1,The activation energy was 62.48 k J/mol and the pre-exponential factor was 1.84 ×10~6. The second step was also the first-order decomposition reaction. The reaction mechanism function was F2. The apparent activation energy was 106.42 kJ/mol and the pre-exponential factor was 2.79×107.
Rare earth oxalates are the common precursors for preparing rare earth oxides, especially rare earth oxides with controlled particle size, which have the advantages of good precipitate crystal form, easy filtration and decomposition, etc. However, kinetic study of the thermal decompositionforcurrent rare earth oxalates was less,Therefore,thethermogravimetry-differential thermal analysis method was used to study the thermal decomposition process of dysprosium hexahydrate. The decomposition kinetics parameters of dysprosium hexahydrate were calculated by Kissinger, Ozawa and Crane methods. Coats-Redfern method was used to find the mechanism function of the reaction.The results showed that the decomposition activation energies calculated by several methods were quite close and the thermal decomposition of dysprosium hexahydrate was carried out in two steps. The first step was the first order dehydration reaction. The reaction mechanism function was F1,The activation energy was 62.48 k J/mol and the pre-exponential factor was 1.84 ×10~6. The second step was also the first-order decomposition reaction. The reaction mechanism function was F2. The apparent activation energy was 106.42 kJ/mol and the pre-exponential factor was 2.79×107.
引文
[1]BUSHUEV N N,ZININ D S.Thermal decomposition features of calcium and rare-earth oxalates[J].Russian Journal of Inorganic Chemistry,2016,61(2):161-167.
[2]M ONTEIRO D D S,SOUZA M O D G.Thermal decomposition of precursors and iron oxide properties[J].Journal of Thermal Analysis and Calorimetry,2016,123(2):1-9.
[3]MELNIKOV P,ARKHANGELSKY I V,NASCIMENTO V A,et al.Thermolysis mechanism of samarium nitrate hexahydrate[J].Journal of Thermal Analysis and Calorimetry,2014,118(3):1537-1541.
[4]易宇,石靖,郭学益.工艺条件对硝酸银溶液雾化热分解制备超细银粉的影响[J].有色金属科学与工程,2015,6(3):6-15.
[5]汤卫东,朱伟伟,姜平国,等.Cu O氯化过程动力学研究[J].有色金属科学与工程,2017,8(1):46-50.
[6]李靖华,张桂恩,黄山.草酸锰分解过程的机理函数判别和动力学研究[J].高等学校化学学报,1991,11:67-72.
[7]潘云祥,管翔颖,冯增媛,等.一种确定固相反应机理函数的新方法-固态草酸镍(Ⅱ)二水合物脱水过程的非等温动力学[J].无机化学学报,1999,15(2):247-251.
[8]邹华红,胡坤,桂柳成,等.一水草酸钙热重-差热综合热分析的最优化表征方法[J].广西科学院学报,2011,27(1):17-21.
[9]FULLER M J,PINKSTONE J.Thermal analysis of the oxalate hexahydrates and decahydrates of yttrium and the lanthanide elements[J].Journal of the Less Common Metals,1980,70(2):127-142.
[10]GALLAGHER P K,SCHREY F,PRESCOTT B.Thermal decomposition of europium(Ⅲ)oxalate.Inorg Chem,1970,9(2):215.
[11]倪兆艾,晁斌,马福泰.程序升温热分析法研究稀土草酸盐(Ⅰ)[J].杭州大学学报,1988,15(4):430-436.
[12]郑晓玲,倪兆艾,晁斌.程序升温热分析法研究稀土草酸盐(Ⅱ)[J].福州大学学报(自然科学版),1997,25(5):92-96.
[13]张克立,陈雄斌,席美云,等.十水草酸镧的热分解机理[J].武汉大学学报(自然科学版),1996,42(2):163-166.
[14]顾翼东,谢高阳,沈民.草酸镨草酸钕及其混合物的热分解[J].复旦大学(自然科学学报),1996(2):313-319.
[15]方正东,汪敦佳.十水草酸铈热分解过程和非等温动力学研究[J].稀土,2005,26(3):19-22.
[16]胡艳宏,李梅,柳召刚,等.大颗粒氧化铈的草酸盐前驱体热分解研究[J].稀土,2009,30(4):34-38.
[17]ZHAN G,YU J X,XU Z G,et al.Kinetics of thermal decomposition of lanthanum oxalate hydrate[J].Transactions of Nonferrous Metals Society of China,2012,22(4):925-934.
[18]ZHANG X H,HE C,WANG L,et al.Non-isothermal kinetic analysis of thermal dehydration of La2(CO3)3﹒3.4H2O in air[J].Transaction s of Nonferrous Metals Society of China,2014,24(10):3378-3385.
[19]AYODELE B V,HOSSAIN M A,CHONG S L,et al.Nonisothermal kinetics and mechanistic study of thermal decomposition of light rare earth metal nitrate hydrates using thermogravimetric analysis[J].Journal of Thermal Analysis and Calorimetry,2016,125(1):423-435.
[20]KOV譧CS T N,HUNYADI D,LUCENA A L A D,et al.Thermal decomposition of ammonium molybdates[J].Journal of Thermal Analysis and Calorimetry,2016,124(2):1013-1021.
[21]KISSINGER H E.Reaction kinetics in differential thermal analysis[J].Analytical Chemistry,1957,29(11):1702-1706.
[22]OZAWA T.Kinetics in differential thermal analysis[J].Bull Chem Soc Jpn,1965,38(11):1881-6.
[23]B ARICK A K,TRIPATHY D K.Thermal and dynamic mechanical characterization of thermoplastic polyurethane/organoclay nanocomposites prepared by melt compounding[J].Materials Science&Engineering A,2010,527(3):812-823.
[24]COATS A W,REDFERN J P.Kinetic parameters from thermogravimetric data[J].Nature,1964,201(4914):68-69.
[25]吴文远.稀土冶金学[M].北京:化学工业出版社,2005:11-13.
[2]M ONTEIRO D D S,SOUZA M O D G.Thermal decomposition of precursors and iron oxide properties[J].Journal of Thermal Analysis and Calorimetry,2016,123(2):1-9.
[3]MELNIKOV P,ARKHANGELSKY I V,NASCIMENTO V A,et al.Thermolysis mechanism of samarium nitrate hexahydrate[J].Journal of Thermal Analysis and Calorimetry,2014,118(3):1537-1541.
[4]易宇,石靖,郭学益.工艺条件对硝酸银溶液雾化热分解制备超细银粉的影响[J].有色金属科学与工程,2015,6(3):6-15.
[5]汤卫东,朱伟伟,姜平国,等.Cu O氯化过程动力学研究[J].有色金属科学与工程,2017,8(1):46-50.
[6]李靖华,张桂恩,黄山.草酸锰分解过程的机理函数判别和动力学研究[J].高等学校化学学报,1991,11:67-72.
[7]潘云祥,管翔颖,冯增媛,等.一种确定固相反应机理函数的新方法-固态草酸镍(Ⅱ)二水合物脱水过程的非等温动力学[J].无机化学学报,1999,15(2):247-251.
[8]邹华红,胡坤,桂柳成,等.一水草酸钙热重-差热综合热分析的最优化表征方法[J].广西科学院学报,2011,27(1):17-21.
[9]FULLER M J,PINKSTONE J.Thermal analysis of the oxalate hexahydrates and decahydrates of yttrium and the lanthanide elements[J].Journal of the Less Common Metals,1980,70(2):127-142.
[10]GALLAGHER P K,SCHREY F,PRESCOTT B.Thermal decomposition of europium(Ⅲ)oxalate.Inorg Chem,1970,9(2):215.
[11]倪兆艾,晁斌,马福泰.程序升温热分析法研究稀土草酸盐(Ⅰ)[J].杭州大学学报,1988,15(4):430-436.
[12]郑晓玲,倪兆艾,晁斌.程序升温热分析法研究稀土草酸盐(Ⅱ)[J].福州大学学报(自然科学版),1997,25(5):92-96.
[13]张克立,陈雄斌,席美云,等.十水草酸镧的热分解机理[J].武汉大学学报(自然科学版),1996,42(2):163-166.
[14]顾翼东,谢高阳,沈民.草酸镨草酸钕及其混合物的热分解[J].复旦大学(自然科学学报),1996(2):313-319.
[15]方正东,汪敦佳.十水草酸铈热分解过程和非等温动力学研究[J].稀土,2005,26(3):19-22.
[16]胡艳宏,李梅,柳召刚,等.大颗粒氧化铈的草酸盐前驱体热分解研究[J].稀土,2009,30(4):34-38.
[17]ZHAN G,YU J X,XU Z G,et al.Kinetics of thermal decomposition of lanthanum oxalate hydrate[J].Transactions of Nonferrous Metals Society of China,2012,22(4):925-934.
[18]ZHANG X H,HE C,WANG L,et al.Non-isothermal kinetic analysis of thermal dehydration of La2(CO3)3﹒3.4H2O in air[J].Transaction s of Nonferrous Metals Society of China,2014,24(10):3378-3385.
[19]AYODELE B V,HOSSAIN M A,CHONG S L,et al.Nonisothermal kinetics and mechanistic study of thermal decomposition of light rare earth metal nitrate hydrates using thermogravimetric analysis[J].Journal of Thermal Analysis and Calorimetry,2016,125(1):423-435.
[20]KOV譧CS T N,HUNYADI D,LUCENA A L A D,et al.Thermal decomposition of ammonium molybdates[J].Journal of Thermal Analysis and Calorimetry,2016,124(2):1013-1021.
[21]KISSINGER H E.Reaction kinetics in differential thermal analysis[J].Analytical Chemistry,1957,29(11):1702-1706.
[22]OZAWA T.Kinetics in differential thermal analysis[J].Bull Chem Soc Jpn,1965,38(11):1881-6.
[23]B ARICK A K,TRIPATHY D K.Thermal and dynamic mechanical characterization of thermoplastic polyurethane/organoclay nanocomposites prepared by melt compounding[J].Materials Science&Engineering A,2010,527(3):812-823.
[24]COATS A W,REDFERN J P.Kinetic parameters from thermogravimetric data[J].Nature,1964,201(4914):68-69.
[25]吴文远.稀土冶金学[M].北京:化学工业出版社,2005:11-13.