Non-isothermal crystallization kinetics of Fischer-Tropsch wax based on differential scanning calorimetry
The non-isothermal crystallization process of six narrow fractions Fischer-Tropsch waxes with drop melting points of 113,104,92,83,78 and 73℃at different cooling rates were studied by differential scanning calorimetry(DSC).The crystallization kinetic parameters were predicted by Jeziorny method and Mo Zhishen method.The non-isothermal crystalliza-tion activation energy was calculated by Kissinger equation.The results show that the non-isothermal crystallization process of different wax samples is similar and the crystallization process depends on the cooling rates.The kinetic model is in good a-greement with the experimental data.The average value of Avrami index n is between 1 and 2,indicating that the crystalliza-tion process is secondary nucleation,and the rod or fibrous crystals are formed after nucleation.The smaller the non-isother-mal crystallization activation energy of wax samples or the faster the cooling rates,the more prone to crystallization.
Fischer-Tropsch waxdifferential scanning calorimetrynon-isothermal crystallizationcrystallization kineticscrystallization activation energy