Quantitative 29Si FT-NMR spectra of sodium silicate solutions was used to characterize the distribution of soluble silicate species as a function of solution composition. Silica, alumina, and soda concentrations were employed that are characteristic of those used for zeolite synthesis [1-3 mol% SiO2; SiO2/Na2O = 1-3; 0-0.5 mol% Al 2O3]. Silicate structures containing one to twelve Si atoms have been identified. The concentration of these species is a strong function of silicate ratio and can be maximized by adjusting that ratio. Aluminate ions readily react with silicate ions to form new structures containing one or two Si atoms bonded to one Al atom.
Bibliographical noteFunding Information:
This work was supported by the Office of Basic Energy Sciences, Material Sciences Division of the U.S. Department of Energy under Contract DE-AC03-76SF00098. Fellowship support for Alon V. McCormick was provided by the National Science Foundation.