Y_2O_3前驱体热分解过程及动力学研究
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摘要
用热重-差热分析法对Y_2O_3前驱体Y_2(CO_3)_3和Y_2(C_2O_4)_3水合物热分解过程及动力学进行分析,通过Kissinger法、 Ozawa法和Coast-Redfern法等对实验数据进行处理,得出Y_2(C_2O_4)_3水合物的热分解分四步进行,前两步为脱水过程,后两步为分解过程,四步反应对应的活化能E_c分别为64.24, 59.48, 146.20和112.37 kJ·mol~(-1);指前因子A_c分别为:4.09×10~8, 3.83×10~5, 6.86×10~(10)和6.18×10~5。每一步的机制函数分别是:1-(1-α)~(1/2)=kt, 1-(1-α)~(1/3)=kt,[(1-α)~(-2)-1]/2=kt和[-ln(1-α)]~(1/3)=kt。而Y_2(CO_3)_3在空气中热分解只有两步,第一步脱3个H_2O和1个CO_2分子,第二步脱2个CO_2分子生成Y_2O_3,两步对应的活化能E_c分别为88.29和116. 53 kJ·mol~(-1),指前因子A_c分别为1.5×10~(13)和9.4×10~7。它们的机制函数分别为(1-α)~(-1)-1=kt和[1-(1-α)~(1/3)]~2=kt。前驱体Y_2(CO_3)_3水合物相对来说比Y_2(C_2O_4)_3水合物更易分解生成Y_2O_3,两种前驱体的热分解都是最后一步为控速步骤。
The thermal decomposition process and kinetics of yttrium oxide precursor of yttrium carbonate and yttrium oxalate were analyzed by means of thermogravimetric-differential thermal analysis, and the experimental data were processed by the methods of Kissinger, Ozawa and Coast-Redfern. The results showed that there are four steps for thermal decomposition of yttrium oxalate, the first two steps are the dehydration process, the following two steps are the decomposition process, and the activation energy E_c corresponding to the four-step reaction are 64.24, 59.48, 146.20 and 112.37 kJ·mol~(-1), the preexponential factors A_c are 4.09×10~8, 3.83×10~5, 6.86×10~(10) and 6.18×10~5, respectively. The mechanism functions of each step are 1-(1-α)~(1/2)=kt, 1-(1-α)~(1/3)=kt, [(1-α)~(-2)-1]/2=kt and [-ln(1-α)]~(1/3)=kt. The thermal decomposition of yttrium carbonate includes two steps, the first step is the taking off of three H_2O and one CO_2 molecules′, the second step is giving off two CO_2 molecules′ and then generating yttrium oxide. The activation energy E_c corresponding to the two steps are 88.29 and 116.53 kJ·mol~(-1), their preexponential factors A_c are 1.5×10~(13) and 9.4×10~7, respectively. The mechanism functions are(1-α)~(-1)-1=kt and [1-(1-α)~(1/3)]~2=kt. The precursor of yttrium carbonate is more easily decomposed than yttrium oxalate to produce yttrium oxide, and the speed controlling step of the thermal decomposition of the two precursors is the last step.
The thermal decomposition process and kinetics of yttrium oxide precursor of yttrium carbonate and yttrium oxalate were analyzed by means of thermogravimetric-differential thermal analysis, and the experimental data were processed by the methods of Kissinger, Ozawa and Coast-Redfern. The results showed that there are four steps for thermal decomposition of yttrium oxalate, the first two steps are the dehydration process, the following two steps are the decomposition process, and the activation energy E_c corresponding to the four-step reaction are 64.24, 59.48, 146.20 and 112.37 kJ·mol~(-1), the preexponential factors A_c are 4.09×10~8, 3.83×10~5, 6.86×10~(10) and 6.18×10~5, respectively. The mechanism functions of each step are 1-(1-α)~(1/2)=kt, 1-(1-α)~(1/3)=kt, [(1-α)~(-2)-1]/2=kt and [-ln(1-α)]~(1/3)=kt. The thermal decomposition of yttrium carbonate includes two steps, the first step is the taking off of three H_2O and one CO_2 molecules′, the second step is giving off two CO_2 molecules′ and then generating yttrium oxide. The activation energy E_c corresponding to the two steps are 88.29 and 116.53 kJ·mol~(-1), their preexponential factors A_c are 1.5×10~(13) and 9.4×10~7, respectively. The mechanism functions are(1-α)~(-1)-1=kt and [1-(1-α)~(1/3)]~2=kt. The precursor of yttrium carbonate is more easily decomposed than yttrium oxalate to produce yttrium oxide, and the speed controlling step of the thermal decomposition of the two precursors is the last step.
引文
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[13] Coast A W, Redfern J P. Kinetic parameters from thermogravimetric data [J]. Nature, 1964, 201(4914): 68.
[14] Ozawa T. Kinetics in differential thermal analysis [J]. Bull. Chem. Soc. Jpn., 1965, 38(11): 1881.
[15] 邓庚凤, 姬传红, 谢耀, 谭敏, 蔡晨龙, 王赟, 曾青云. 十水草酸镧的热分解及其动力学分析 [J]. 材料与冶金学报, 2017, 16(2): 116.Deng G F, Ji C H, Xie Y, Tan M, Cai C L, Wang Y, Zeng Q Y. Thermal decomposition and kinetics analysis of lanthanum oxalate decahydrate [J]. Journal of Materials and Metallurgy, 2017, 16(2): 116.
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[2] 肖卓豪, 左成钢, 朱立刚, 陈媛媛, 卢安贤. 氧化钇对CaO-BaO-Al_2O_3-SiO_2-GeO_2系玻璃结构与性能的影响 [J]. 中国有色金属学报, 2008, 18(11): 2068.Xiao Z H, Zuo C G, Zhu L G, Chen Y Y, Lu A X. Effects of yttria on structure and properties of CaO-BaO-Al_2O_3-SiO_2-GeO_2 glasses [J]. The Chinese Journal of Nonferrous Metals, 2008, 18(11): 2068.
[3] 刘文燕, 徐坦, 刘璐, 夏风, 肖建中. 氧化钇对氧化铝陶瓷致密化的影响 [J]. 人工晶体学报, 2016, 45(7): 1741.Liu W Y, Xu T, Liu L, Xia F, Xiao J Z. Influence of yttria on alumina ceramic densification [J]. Journal of Synthetic Crystals, 2016, 45(7): 1741.
[4] 吴洪达, 贾佑顺, 张兵兵, 张泽远, 叶海梅. 球形纳米氧化钇的制备与表征 [J]. 无机盐工业, 2016, 48(7): 29.Wu H D, Jia Y S, Zhang B B, Zhang Z Y, Ye H M. Preparation and characterization of spherical nano-sized Y_2O_3 powders [J]. Inorganic Chemicals Industry, 2016, 48(7): 29.
[5] 霍地, 孙旭东, 修稚萌, 李晓东. 制备工艺对超细氧化钇粉体形态与烧结性的影响 [J]. 中国稀土学报, 2007, 25(5): 566.Huo D, Sun X D, Xiu Z M, Li X D. Influence of processing conditions on morphologies and sinterability of ultrafine Y_2O_3 powders [J]. Journal of the Chinese Society of Rare Earths, 2007, 25(5): 566.
[6] 刘志强, 李杏英, 梁振锋. 碳铵沉淀法制备纳米氧化钇过程中氯离子的行为 [J]. 中国稀土学报, 2005, 23(3): 373.Liu Z Q, Li X Y, Lian Z F. Action of chlorione during preparation of nanometer yttrium oxide by precipitation with ammonium bicarbonate [J]. Journal of the Chinese Society of Rare Earths, 2005, 23(3): 373.
[7] 李慧琴, 李健, 赵永志, 张瑞祥, 郝先库, 马显东. 碳酸氢铵沉淀法制备大颗粒球形氧化钇的研究 [J]. 稀土, 2014, 35(3): 77.Li H Q, Li J, Zhao Y Z, Zhang R X, Hao X K, Ma X D. Study on preparation of yttrium oxide with large particle sizes and spherical shapes by precipitation with ammonium bicarbonate [J]. Chinese Rare Earths, 2014, 35(3): 77.
[8] 雷立. 氧化钇超细粉体制备及动力学研究 [D]. 柳州: 广西工学院, 2011. 29.Lei Li. Study on the Preparation and Kinetics of Yttria Ultrafine Powders [D]. Liuzhou: Guangxi Engineering College, 2011. 29.
[9] 薛松, 吴明, 徐志高, 池汝安. 撞击流-活性炭吸附法制备氧化钇超细粉体 [J]. 稀有金属, 2012, 36(3): 439.Xue S, Wu M, Xu Z G, Chi R A. Preparation of ultra-fine Y_2O_3 powder by activated carbon adsorption in submerged circulative impinging stream reactor [J]. Chinese Journal of Rare Metals, 2012, 36(3): 439.
[10] 李玲. 常温碳酸盐法合成高纯纳米Y_2O_3 [J]. 稀土, 2005, 26(2): 11.Li L. Synthesis of Y_2O_3 nanopowder by carbonate method at room temperature [J]. Chinese Rare Earths, 2005, 26(2): 11.
[11] 闫勇, 朱伟长, 李辉生. 氧化钇纳米粉体材料的制备 [J]. 化工新型材料, 2004, 32(7): 10.Yan Y, Zhu W C, Li H S. Preparation of yttrium oxide nanopowders [J]. New Chemical Materials, 2004, 32(7): 10.
[12] Kissinger H E. Reaction kinetics in differential thermal analysis [J]. Anal. Chem., 1957, 29(11): 1702.
[13] Coast A W, Redfern J P. Kinetic parameters from thermogravimetric data [J]. Nature, 1964, 201(4914): 68.
[14] Ozawa T. Kinetics in differential thermal analysis [J]. Bull. Chem. Soc. Jpn., 1965, 38(11): 1881.
[15] 邓庚凤, 姬传红, 谢耀, 谭敏, 蔡晨龙, 王赟, 曾青云. 十水草酸镧的热分解及其动力学分析 [J]. 材料与冶金学报, 2017, 16(2): 116.Deng G F, Ji C H, Xie Y, Tan M, Cai C L, Wang Y, Zeng Q Y. Thermal decomposition and kinetics analysis of lanthanum oxalate decahydrate [J]. Journal of Materials and Metallurgy, 2017, 16(2): 116.
[16] 左金琼. 热分析中活化能的求解与分析 [D]. 南京: 南京理工大学, 2006. 6.Zuo J Q. Solving and Analysis of Activation Energy in Thermal Analysis [D]. Nanjing: Nanjing University of Science and Technology, 2006. 6.