Pure Al2O3-2SiO2 powders were prepared by sol-gel and coprecipitation methods, and their alkaliactivation reactivities were compared. The alkali-activation reactivity of the powder prepared by the so]-gel method was h...Pure Al2O3-2SiO2 powders were prepared by sol-gel and coprecipitation methods, and their alkaliactivation reactivities were compared. The alkali-activation reactivity of the powder prepared by the so]-gel method was higher than that of the powder prepared by the coprecipitation method. The powders were investigated by 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy （MAS NMR） to understand the relationship between their structure and alkali-activation reactivity. The 27Al MAS NMR data showed that the five-coordinate AI content of the powder prepared by the sol-gel method was higher than that of the powder prepared by coprecipitation. The higher content of five-coordinate Al corresponded to higher alkali-activation reactivity. The 29Si MAS NMR data showed that for the powder prepared by the sol-gel method, silicon was replaced by aluminum at secondary coordination sites of the central Si atoms during calcination. However, for the powder prepared by single-batch coprecipitation, the main change was from a low degree of polycondensation to a high degree of polycondensation.展开更多
基金supported by the Chinese Natural Science Fund (Grant Nos.51262002 and 50962002)Guangxi Experiment Center of Science and Technology(Grant No.LGZXKF201202)+2 种基金Guangxi Natural Science Fund(Grant No.2014GXNSFAA118323)Research Project of the Education Department of Guangxi Government (Grant No.201204LX238)Opening Fund of Doctor Station Construction of Guangxi Teachers Education University
文摘Pure Al2O3-2SiO2 powders were prepared by sol-gel and coprecipitation methods, and their alkaliactivation reactivities were compared. The alkali-activation reactivity of the powder prepared by the so]-gel method was higher than that of the powder prepared by the coprecipitation method. The powders were investigated by 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy （MAS NMR） to understand the relationship between their structure and alkali-activation reactivity. The 27Al MAS NMR data showed that the five-coordinate AI content of the powder prepared by the sol-gel method was higher than that of the powder prepared by coprecipitation. The higher content of five-coordinate Al corresponded to higher alkali-activation reactivity. The 29Si MAS NMR data showed that for the powder prepared by the sol-gel method, silicon was replaced by aluminum at secondary coordination sites of the central Si atoms during calcination. However, for the powder prepared by single-batch coprecipitation, the main change was from a low degree of polycondensation to a high degree of polycondensation.
