Recrystallization of a new layered silicate from Na-kanemite–tetramethylammonium hydroxide–water–1,4-dioxane mixture

Abstract

Na-kanemite has been completely converted to a new layered silicate in a reaction mixture of tetramethylammonium hydroxide (TMAOH) solution, water and 1,4-dioxane as solvent via hydrothermal treatment at temperatures above 130 °C. The effects of the content of TMAOH and water as well as the type of organic solvents on the conversion of Na-kanemite were investigated. TMA and Na cations were found to be essential for the formation of the new phase (designated as KLS3). Without the use of organic solvent, Na-kanemite was also converted to a KLS3 phase at higher temperatures (e.g.150 °C) and for 5 days. 29Si MAS NMR and FT-IR data indicated that a structural change into the kanemite sheets occurred leading to the formation of a three-dimensional silicate network where Q4 silicon species were detected.