AlF_3·3H_2O非等温热分解动力学

Thermal decomposition kinetics of AlF_3·3H_2O under non isothermal condition

采用 TG-DTG法确定了三水氟化铝的热分解过程分三步进行 ,求得了第一步脱水反应的表观活化能( E)和指前因子 ( A)分别为 4 1 .9k J/mol和 1 0 2 .49s- 1 ;第二步脱水反应的 E为 4 7.5k J/mol,其非等温动力学方程为 -ln( 1 -α) =A· exp( -E/RT)· t;在 3 80℃以上 ,Al F3发生水解反应 ,其 E和非等温动力学方程分别是 80 .4 k J/mol和 [-ln( 1 -α) ]23=A· exp( -E/RT)· t.当第二步脱水反应与水解反应在 3 80～ 550℃同时发生时 ,脱水反应比水解反应更易进行 .

By using the TG DTG measurements, three stages have been recognized in the thermal decomposition of AlF 3·3H 2O. For the first stage dehydration, the value of the apparent activation energy, E , and the preexponential factor, A, have been determined to be 41 9kJ·mol -1 and 10 2 49 s -1 respectively. For the second stage dehydration, the value of E is 47 5 kJ·mol -1 . The non isothermal kinetics equation is ln ( 1-α)=A· exp(- E/RT)·t . As the temperature exceeds 380 ℃, a hydrolytic reaction of AlF 3 with water begins. In this stage, the apparent activation energy, E , is 80 4kJ·mol -1 , and the non isothermal kinetics equation is [-ln( 1-α)] 2/3 =A· exp (-E/RT)·t .With the temperature ranging between 380 and 550 ℃,the dehydration reaction and the hydrolytic reaction happens at the same time, but the former is easier to happen than the latter.