A new method for the calculation of Gibbs free energy of formation of zeolites is introduced, which is based on the assumption that the Gibbs free energy of formation of zeolites is equal to the sum of the Gibbs free ...A new method for the calculation of Gibbs free energy of formation of zeolites is introduced, which is based on the assumption that the Gibbs free energy of formation of zeolites is equal to the sum of the Gibbs free energy of all oxide components and the Gibbs free energy of reaction between the exchange ion oxide and alumina.The Gibbs free energy values of many zeolites were calculated.The results showed that the deviation between the experimental value of ΔG<sup><sup>0<sub>f of zeolite formation and those calculated by this method was less than 1%, and the molar Gibbs free energy of formation of hypothetical [SiO2] unit in each zeolite was below that of silica of all phase states.The presence of crystal water in zeolite was in favor of increasing the thermodynamic stability of zeolite.展开更多
Web-like ZnO nanostructures have been successfully synthesized using the potassium nitrate route at various temperatures to simplify conventional preparation methods. The structures and morphologies of the as-prepared...Web-like ZnO nanostructures have been successfully synthesized using the potassium nitrate route at various temperatures to simplify conventional preparation methods. The structures and morphologies of the as-prepared products were characterized by X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The results showed that the reaction temperature was an important parameter, and that there was a feedback effect between nano-structure and growth parameters, combined with in situ micro-calorimetry, the reaction rate constants of the three systems were found to have been: 2.43×10-6, 2.70×10-8 and 3.12×10-7s-1 respectively. Furthermore, based on the relationship governing the potential differences between nanoand bulk ZnO, thermodynamic functions of nano-ZnO such as standard molar entropy (Sm,ZnO(nano)), standard molar Gibbs free energy of formation (△rGm,ZnO(nano)), and standard molar enthalpy of formation (△rHm,ZnO(nano)) have been calculated by the electrochemical method.展开更多
文摘A new method for the calculation of Gibbs free energy of formation of zeolites is introduced, which is based on the assumption that the Gibbs free energy of formation of zeolites is equal to the sum of the Gibbs free energy of all oxide components and the Gibbs free energy of reaction between the exchange ion oxide and alumina.The Gibbs free energy values of many zeolites were calculated.The results showed that the deviation between the experimental value of ΔG<sup><sup>0<sub>f of zeolite formation and those calculated by this method was less than 1%, and the molar Gibbs free energy of formation of hypothetical [SiO2] unit in each zeolite was below that of silica of all phase states.The presence of crystal water in zeolite was in favor of increasing the thermodynamic stability of zeolite.
基金supported by the China Manned Space Engineering Program(Fluid Physics Experimental Rack and the Priority Research Program of Space Station)the National Natural Science Foundation of China(Grant No.12032020).
基金supported by the National Natural Science Foundation of China (20963001,21273050)Guangxi Natural Science Foundation of China (0991001z,2011GXNSFB018021)
文摘Web-like ZnO nanostructures have been successfully synthesized using the potassium nitrate route at various temperatures to simplify conventional preparation methods. The structures and morphologies of the as-prepared products were characterized by X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The results showed that the reaction temperature was an important parameter, and that there was a feedback effect between nano-structure and growth parameters, combined with in situ micro-calorimetry, the reaction rate constants of the three systems were found to have been: 2.43×10-6, 2.70×10-8 and 3.12×10-7s-1 respectively. Furthermore, based on the relationship governing the potential differences between nanoand bulk ZnO, thermodynamic functions of nano-ZnO such as standard molar entropy (Sm,ZnO(nano)), standard molar Gibbs free energy of formation (△rGm,ZnO(nano)), and standard molar enthalpy of formation (△rHm,ZnO(nano)) have been calculated by the electrochemical method.
