摘要:
以五水硝酸铋(Bi(NO3)3·5H2O)及偏钒酸铵(NH4VO3)为原料,利用TG-DSC对固相煅烧法制备钒酸铋的动力学进行研究。结果表明:不同升温速率下,反应均经历两个阶段,第一阶段的DSC峰值温度为400.67~425.95K,反应同时在固、液两相中进行;第二阶段的DSC峰值温度为516.86~551.57K,为固相反应;两个阶段的反应均涉及到体系副产物的分解及产物晶型的转变与完善。分别通过Flynn-Wall-Ozawa及Kissinger模型确定出两个阶段反应的动力学参数。第一阶段,表观活化能Ea1=86.56kJ/mol,频率因子A1=4.49×1010min-1;第二阶段,表观活化能Ea2=103.11kJ/mol,频率因子A2=4.12×109min-1。
Abstract:
The kinetics of Bi VO4 prepared by the solid reaction of Bi (NO3)3·5H2O and NH4VO3 was investigated using TG-DSC under different heating rates. The results show that the process undergoes two stages. The first period corresponds to the solid and liquid-state reactions and the second period is a solid-state reaction with 400.67~425.95 K,516.86~551.57 K of peak temperature range in DSC curves,respectively. All the reactions in these periods involve the decomposition of by-products,the transition and perfection of the crystals in product. Employing the Flynn-Wall-Ozawa and Kissinger models,the kinetics parameters for the reactions were determined as follows: for the first period,the apparent activation energy Ea1= 86.56 kJ/mol and frequency factor A1= 4.49 × 1010min-1; for the second period,the apparent activation energy Ea2= 103.11 kJ/mol and frequency factor A2= 4.12 × 109min-1.
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