METHOD OF PRODUCING HIGHLY PURE AQUEOUS SOLUTION OF CERIUM NITRATE (IV) (VERSIONS)

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FIELD : chemistry. SUBSTANCE : invention relates to production of pure compounds of rare-earth elements, specifically cerium nitrate (IV), used in production of catalysts, additives for diesel fuel, luminophores, as well as in optical glass manufacturing. Invention includes two versions of method. First method of producing highly pure aqueous solution of cerium nitrate (IV) when used as raw product of high-purity cerium dioxide, involving a step of forming an intermediate aqueous solution of cerium nitrate (III) and further multi-step treatment thereof, wherein intermediate aqueous solution of cerium nitrate (III) is obtained by treating initial cerium dioxide at 70-80 °C with concentrated nitric acid, containing 1-5 wt% hydrofluoric acid with respect to cerium dioxide, with subsequent addition of hydrogen peroxide in 2-10-fold excess of stoichiometric amount, by heating reaction mass to 90-100 °C while stirring, cooling, filtration and treatment of formed intermediate aqueous solution of cerium nitrate (III) to produce highly pure aqueous solution of cerium nitrate (IV) according to following procedure : heating to 50-60 °C, adding thereto oxalic acid in excess of 5-20 % with respect to stoichiometric amount, separation and thermal treatment of precipitate of cerium oxalate on air at 320-370 °C and further dilution of product of thermal treatment at 80-90 °C, caried out in concentrated nitric acid, used in excess of 1-20 % with respect to stoichiometric amount, to produce end product. Second version is a method of producing highly pure aqueous solution of cerium nitrate (IV) when used as raw product of high purity of cerium nitrate hexahydrate (III), involving a step of forming an intermediate aqueous solution of cerium nitrate (III), obtained with dilution of raw product in deionised water, and further treatment to formation of high-purity aqueous solution of cerium nitrate (IV) according to following procedure : heating to 50-60 °C, adding oxalic acid in excess of 5-20 % with respect to stoichiometric amount, separation and thermal treatment of precipitate of cerium oxalate on air at 320-370 °C and further dilution of product of thermal treatment at 80-90 °C, caried out in concentrated nitric acid, used in excess of 1-20 % with respect to stoichiometric amount, to produce end product. EFFECT : invention enables to obtain highly pure products, which satisfy requirements for purity in modern industries. 2 cl, 1 tbl, 2 ex