AlCl_3与水合草酸混合物的热解动力学

Studies on thermal decomposition kinetics of the mixture of AlCl_3 and oxalic acid

用热重法研究AlCl3与二水合草酸混合物的非等温热分解动力学。在AlCl3与二水合草酸摩尔比不同的情况下,分解过程及分解产物也有所不同。 第一步分解:样品(3:100)分解产物为一水合草酸,样品(6:100; 9:100; 12:100)分解产物为草酸酐。样品(3:100)和样品(6:100; 9:100; 12:100)的机理函数均为8号机理,动力学方程为dα/dt =Ae-Ea/RT(3/2)(1-α)[-ln(1-α)]1/3,但样品(3:100)比样品(6:100; 9:100; 12:100)的活化能要高些. 第二步分解:样品(3:100)对应10号机理,动力学方程为dα/dt =Ae-Ea/RT3(1-α)[-ln(1-α)]2/3. 而样品(6:100; 9:100; 12:100) 对应9号机理,动力学方程为dα/d t= Ae-Ea/RT 2(1-α)[-ln(1-α)]1/2。

AIMS To study the thermal decomposition kinetics and process of the mixture of AlCl3 and oxalic acid dihydrate. METHOD TG-DTG method. RESULT The product of the sample (3:100) is oxalic acid monohydrate and the product of the sample (6:100,9:100,12:100) is oxalic acid anhydride. For the first step of the decomposition of all samples, the mechanism model function is No.8 and the kinetics equation is dα/dt=Ae-Ea/RT(3/2)(1-α)[-ln(1-α)]1/3. For the second step of the sample (3:100), the mechanism model function is No.10 and the kinetics equation is dα/dt=Ae-Ea/RT3(1-α)[-ln(1-α)]2/3; For the second step of the sample (6:100,9:100,12:100), the mechanism model function is No.9and the kinetics equation is dα/dt= Ae-Ea/RT 2(1-α)[-ln(1-α)]1/2. CONCLUSION The thermal decomposition kinetics and process of the samples are different as the contents of the AlCl3 in samples are different. AlCl3 as a Lewis acid affects the activation energy mainly in the dehydroation step.