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采用水热法合成单相La2(C O 3)3·3.4 H2O。采用XRD、FTIR以及DTA-T G对La2(C O 3)3·3.4 H2 O在3 0~1 0 0 0°C的热分解过程、中间及最终产物进行表征。在非等温条件下对L a2(C O3)3·3.4H2O在3 0~3 6 6°C范围内的热脱水动力学进行研究。采用Flynn-Wall-Ozawa及Friedman等转化法计算其反应活化能并对其反应阶段进行分析。采用多元非线性回归程序确定其最可能的反应机理及动力学参数。结果表明,L a2(C O3)3·3.4H 2O的热脱水为三步竞争反应,一个n序列初始反应后为n序列竞争反应(F nF nF n机理)。经最可能的反应机理计算所得的活化能与Friedman等转化法的计算结果非常接近,拟合后的TG及DTG曲线与原始曲线能较好地吻合。
Hydrothermal synthesis of single-phase La2 (C 3 O) 3 · 3.4 H2O. The thermal decomposition process, intermediate and final products of La2 (C 3 O) 3 · 3.4H 2 O at 30 ~ 100 ℃ were characterized by XRD, FTIR and DTA-T G. The thermal dehydration kinetics of L a2 (C O3) 3 · 3.4H2O in the range of 30 ~ 366 ° C was studied under non-isothermal conditions. The reaction activation energies were calculated by Flynn-Wall-Ozawa and Friedman transformation methods and their reaction stages were analyzed. A multivariate nonlinear regression procedure was used to determine the most likely reaction mechanism and kinetic parameters. The results showed that the thermal dehydration of L a2 (C O3) 3 · 3.4H 2 O was a three-step competitive reaction, and the n-sequence competitive reaction (F nF nF n mechanism) after an n-sequence initial reaction. The activation energy calculated by the most probable reaction mechanism is very close to Friedman’s transformation method. The fitted TG and DTG curves are in good agreement with the original curve.