A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and ...A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a 0ebye-Huckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g., reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified. As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2, TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.展开更多
Jatropha curcas L. （JCL） seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures （200-280℃） and pressures （8-12 MPa）, and at...Jatropha curcas L. （JCL） seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures （200-280℃） and pressures （8-12 MPa）, and at a fixed reaction time of 30 min with seeds-to-methanol ratio of 1：40 w/v. Design of experiment approach using five-level-two-factors design of Response Surface Methodology （RSM） was used to observe the effect of two independent variables i.e. temperature and pressure and the percent of biodiesel yield which required 13 runs. For optimization of the variables, Central Composite Rotatable Design （CCRD） was used for regression analysis and analysis of variance （ANOVA）. The optimize conditions suggested by RSM were at T = 280℃ and P = 12.04 MPa. The predicted and experimental biodicsel yields were found to be 56.8% and 59.9%, respectively, with relatively small deviation errors of 1.59%.展开更多
基金Supported by the National Natural Science Foundation of China (No. 20236020, No. 20325621)863 Hi-Technology Research and Development Program of China (No. 2001AA325014)the Talent Training Program of the Beijing City (No. 9558103500)the Fok Ying Tung Foundation (No. 81063).
文摘A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a 0ebye-Huckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g., reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified. As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2, TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.
文摘Jatropha curcas L. （JCL） seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures （200-280℃） and pressures （8-12 MPa）, and at a fixed reaction time of 30 min with seeds-to-methanol ratio of 1：40 w/v. Design of experiment approach using five-level-two-factors design of Response Surface Methodology （RSM） was used to observe the effect of two independent variables i.e. temperature and pressure and the percent of biodiesel yield which required 13 runs. For optimization of the variables, Central Composite Rotatable Design （CCRD） was used for regression analysis and analysis of variance （ANOVA）. The optimize conditions suggested by RSM were at T = 280℃ and P = 12.04 MPa. The predicted and experimental biodicsel yields were found to be 56.8% and 59.9%, respectively, with relatively small deviation errors of 1.59%.
