Process for the preparation of a crystalline, swellable sheet silicate of the saponite type

US4749676A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Thomas Blumenthal · Frankfurt am Main, DE
• Hans-Jurgen Kalz · Liederbach, DE

Key dates

• Filing date: Nov 24, 1986
• Grant date: Jun 7, 1988
• Expiry date: Nov 24, 2006

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B33/40
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A crystalline swellable sheet silicate of the saponite type, of the formula EQU [Mg.sub.6 (Si.sub.8-x Al.sub.x)O.sub.20 (OH).sub.4 ].sup.x-.(x/z)M.sup.z+ n H.sub.2 O in which PA1 x is a number which is less than 1.5 but at least 0.2, PA1 z is an integer from 1 to 3, PA1 M denotes a cation having the valency of z and PA1 n is a number less than 20, is prepared. For this purpose, an aqueous solution or suspension containing magnesium ions, a silica source, an alumina source and a sodium oxide source are combined. The atomic ratio of Mg/Si and Mg/Al used in this procedure correspond to the composition of the desired saponite. The atomic ration (Na-Al):(Mg+Si+3/2.Al) should be between x/5 and 1, Na denoting the amount of sodium atoms present in alkaline compounds. The pH of the reaction mixture should be at least 9.0. The crystals of the resulting synthetic saponite in the sodium form are separated off from the mother liquor and, if appropriate, treated with an aqueous solution or suspension of a salt having the cation M.sup.z+, and, when cation exchange is complete, are separated off from the aqueous phase.