Co-precipitation method was employed to prepare LaMnAl11O19 catalyst for methane combustion.Sodium carbonate was used as precipitator in the process.The influences of precipitation temperature on the structure and pro...Co-precipitation method was employed to prepare LaMnAl11O19 catalyst for methane combustion.Sodium carbonate was used as precipitator in the process.The influences of precipitation temperature on the structure and property of the catalysts were investigated by XRD、SEM、BET techniques.The optimal calcination temperature of the catalysts was determined.The results show that the crystal phase and activity for methane combustion are greatly affected by precipitation temperature,and hexaaluminates with high activity were formed when catalysts were calcinated at 1 200 ℃ for 4 h. Typically at the precipitation temperature of 90 ℃,the specific surface area of the catalyst is about 19.6 m2/g,and the light-off temperature(T10% for methane combustion is 432 ℃ and the full conversion temperature is 712 ℃.展开更多
A thermodynamics analysis on the leaching process of selenium residue and discussion on the behaviors of aqueous ionic in the leaching process were carried out. Through thermodynamical calculation, the values of AG an...A thermodynamics analysis on the leaching process of selenium residue and discussion on the behaviors of aqueous ionic in the leaching process were carried out. Through thermodynamical calculation, the values of AG and relevant potential expressions were obtained. According to these thermodynamical data, the φ-pH diagrams of Se-H2O system at 298 and 373 K were obtained; Simultaneously, the φ-pH diagrams of SO2-H2O and SO2-Se-H2O systems were drawn at 298 K. With increasing the temperature, the stable regions of HSeO3, SeO2- and SeO2- in the φ-pH diagram of Se-H2O system become gradually large, but the limits of pH in the stable region become gradually small. The stability area of reduction precipitation in the SO2-Se-H2O system was finally determined. The results of oxidization leaching experiments of selenium residue indicate that when the mass ratio of selenium residue to sodium chlorate is 2, the concentration of sulfuric acid is 300 g/L and the residue is agitated for 3 h at leaching temperature of 80 ℃, the leaching rate of selenium could reach 97.76 %. The experimental results conform the calculated results by φ-pH diagram. The selenium reduction precipitation in oxidization-leaching solution was analyzed under the conditions of acidity of 150 g/L, the sodium sulphite concentration of 35 g/L at the reductive temperature of 23 ℃ for 120 min. And this demonstrates the thermodynamics analysis.展开更多
文摘Co-precipitation method was employed to prepare LaMnAl11O19 catalyst for methane combustion.Sodium carbonate was used as precipitator in the process.The influences of precipitation temperature on the structure and property of the catalysts were investigated by XRD、SEM、BET techniques.The optimal calcination temperature of the catalysts was determined.The results show that the crystal phase and activity for methane combustion are greatly affected by precipitation temperature,and hexaaluminates with high activity were formed when catalysts were calcinated at 1 200 ℃ for 4 h. Typically at the precipitation temperature of 90 ℃,the specific surface area of the catalyst is about 19.6 m2/g,and the light-off temperature(T10% for methane combustion is 432 ℃ and the full conversion temperature is 712 ℃.
基金Project(51072233) supported by the National Natural Science Foundation of China
文摘A thermodynamics analysis on the leaching process of selenium residue and discussion on the behaviors of aqueous ionic in the leaching process were carried out. Through thermodynamical calculation, the values of AG and relevant potential expressions were obtained. According to these thermodynamical data, the φ-pH diagrams of Se-H2O system at 298 and 373 K were obtained; Simultaneously, the φ-pH diagrams of SO2-H2O and SO2-Se-H2O systems were drawn at 298 K. With increasing the temperature, the stable regions of HSeO3, SeO2- and SeO2- in the φ-pH diagram of Se-H2O system become gradually large, but the limits of pH in the stable region become gradually small. The stability area of reduction precipitation in the SO2-Se-H2O system was finally determined. The results of oxidization leaching experiments of selenium residue indicate that when the mass ratio of selenium residue to sodium chlorate is 2, the concentration of sulfuric acid is 300 g/L and the residue is agitated for 3 h at leaching temperature of 80 ℃, the leaching rate of selenium could reach 97.76 %. The experimental results conform the calculated results by φ-pH diagram. The selenium reduction precipitation in oxidization-leaching solution was analyzed under the conditions of acidity of 150 g/L, the sodium sulphite concentration of 35 g/L at the reductive temperature of 23 ℃ for 120 min. And this demonstrates the thermodynamics analysis.
