Alkali-activation reactivity of chemosynthetic Al2O3–2SiO2 powders and their 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectra--颗粒学报PARTICUOLOGY

Zheng, G., Cui, X., Huang, D., Pang, J., Mo, G., Yu, S., & Tong, Z. (2015). Alkali-activation reactivity of chemosynthetic Al2O3–2SiO2 powders and their 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectra. Particuology, 22, 151-156. https://doi.org/10.1016/j.partic.2014.10.006

Alkali-activation reactivity of chemosynthetic Al₂O₃–2SiO₂ powders and their 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectra

Guangjian Zheng ^{a b}, Xuemin Cui ^a, Dong Huang ^b, Jinying Pang ^b, Guowei Mo ^b, Shujuan Yu ^b, Zhangfa Tong ^a *

a School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
b College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001, China

0.1016/j.partic.2014.10.006

Volume 22, October 2015, Pages 151-156

Received 28 June 2014, Revised 26 September 2014, Accepted 2 October 2014, Available online 14 February 2015, Version of Record 4 August 2015.

E-mail: zhftong@sina.com

Highlights

• Powder prepared by sol–gel method had higher alkali-activation reactivity.

• The powders were investigated by ²⁷Al and ²⁹Si MAS NMR.

• The Al(V) contents of the powders were in agreement with their alkali-activation reactivities.

• Si was replaced by Al at secondary coordination sites during calcination of the powders.

Abstract

Pure Al₂O₃–2SiO₂ powders were prepared by sol–gel and coprecipitation methods, and their alkali-activation 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 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 Al 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.

Graphical abstract

Keywords

Geopolymer; Al₂O₃–2SiO₂ powder; Alkali-activation reactivity; NMR; Chemosynthesis

文章导读