Thermal Decomposition Mechanism And Kinetics Analysis Of Carboxylate

Thermal analysis is one of important characters for solid compounds. Thermal analysis is to investigate the physical and chemical process during material is heated, which is a absolutely necessary measurement for investigate on thermal stability of materials. Recently, with the improvement of thermal analysis apparatus's precision especially the introduction of excellent kinetic soft, thermal analysis technique become more important for investigate the inorganic compounds including coordinates.In present thesis, the thermal stability of phthalates in nitrogen atmosphere was studied by thermal technique( TG, DTA, DSC et al ), thermal decomposition mechanism was discussed; thermal decomposition kinetics of nickel oxalate and magnesium phthalate were studied by model-free and model-fitting method, the most probable kinetic triplet was obtained, which offer a new data for decomposition of these kind of materials. The results were listed as below:1. For thermal decomposition of alkli- and rare-earth metal phthalates in nitrogen atmosphere, C-C and C-0 bond rupture is mainly proceeded, thus radicals are formed. New organic compounds such as benzophenone and anthroquinone were produced after the radicals were reorganized, which are difficult to synthesis with common methods. The last solid residue is generally metal oxides or carbonates.2. The decomposition of NiC₂O₄·H₂O in air atmosphere proceeded in two stages: it first lost two crystal water to form anhydrate salt, then anhydrate salt decomposed further. The last solid product was nickel oxides. Kinetics analysis of NiC₂O₄·2H₂O decomposition steps was performed under non-isothermal conditions. The activation energies were calculated through Friedman and Flynn-Wall-Ozawa (FWO) methods, and the most possible kinetic model function has been estimated through the multiple-linear regression method. Thosewere f(a) = (1 - α)ⁿ (1 + K_catα) , f(a) = (1 - α) (1 + K_catα) , respectively. Theactivation energies for the two decomposition steps of NiC₂O₄·H₂O were 171.1 and 174.4kJ/mol, respectively.3. Kinetic analysis was carried out for thermal decomposition of magnesium phthalate in the range of 400⁶00°C. It was found that the thermal decomposition was proceeded in two stages by model-free analysis. At the same time, the initial value of Ea and lgA for model-fitting analysis was obtained. The most possible kinetic triplet was obtained through multiple non-linear regression method. The results are as following: the most possible kinetic model function are Fn -*? Fn,f(cc) = (\- a)n, n=1.33> 0.69, respectively. The optimized activation energyEa=232.24 445.36KJ/mol, lgA= 13.26, 27.78S'1, respectively.