PROCESS FOR THE PREPARATION OF INORGANIC COMPOUNDS

摘要

A process for preparing a compound of formula (1): A>Y<XM>12<O>40<, wherein A is selected from the group consisting of hydrogen, alkali metal and ammonium, X is silicon or phosphorus, M is selected from the group consisting of molybdenum, tungsten and vanadium, and Y is an integer from 1 to 8, which process comprises forming an aqueous liquor comprising the components, (a) an alkali metal salt of a compound comprising an atom denoted by X, (b) an alkali metal salt of a compound comprising an atom denoted by M, and (c) an acid having a pKa below 4, increasing the temperature of the aqueous liquor, and optionally adding more acid, having a pKa below 4, characterised in that the aqueous liquor is formed at a temperature of below 50 DEG C and i) has a pH of below 2 or ii) in which component (c) is present in an amount between 1 and 3 moles per mole of components (b). The invention provides a simple, economic process for the convenient preparation of heteropoly acids, especially silicotungstic acid with a low counter ion content in high yield and high purity and avoids the undesirable formation of silicic acid gels.