Alkali-activation reactivity of chemosynthetic Al_2O_3-2SiO_2 powders and their ~(27)Al and ~(29)Si

• 作 者: Guangjian Zheng Xuemin Cui Dong Huang Jinying Pang Guowei Mo Shujuan Yu Zhangfa Tong
• 机 构: School of Chemistry and Chemical Engineering,Guangxi University,College of Chemistry and Life Scienc
• 出 处: Particuology
• 发表日期: 2015年05期
• 关键词: powders Al and reactivity alkali batch calcination Alkali magic calcined spinnin

Pure Al_2O_3-2SiO_2 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 sol-gel method was higher than that of the powder prepared by the coprecipitation method.The powders were investigated by ~(27)AI and ~(29)Si magic-angle spinning nuclear magnetic resonance spectroscopy(MAS NMR) to understand the relationship between their structure and alkali-activation reactivity.The ~(27)Al 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 ~(29)Si 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.

Pure Al 2 O 3 -2SiO 2 powders were prepared by sol-gel and coprecipitation methods, and their alkaliactivation reactivities were compared. Alkali-activation reactivity of the powder prepared by the sol-gel method was higher than that of the powder prepared by the coprecipitation method. The powders were investigated by (27) AI and ~ (29) Si magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) to understand the relationship between their structure and alkali-activation reactivity. ~ (27) Al 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 Aligned to higher alkali-activation reactivity. Si 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. Host, for the powder prepared by single- batch coprecipitation, the main change was from a low degree of polycondensation to a high degree of polycondensation.