METHOD FOR PRODUCING DISPERSED MESOPOROUS POWDERS BASED ON ALUMINUM OXIDE FOR CATALYST CARRIERS

摘要

FIELD: technological processes.;SUBSTANCE: invention relates to synthesis of dispersed mesoporous materials in the system ZrO₂(Y₂O₃)-Al₂O₃ for catalyst carriers, the claimed method is realized in two stages, wherein in the first stage in the process of coprecipitation of hydroxides in the ZrO₂-Y₂O₃ system three portions of gelatinous precipitation are obtained, and coprecipitation is carried out from 0.1 M solutions of nitric acid salts of zirconium and yttrium, taken in the ratio necessary to obtain a final composition of ZrO₂ (3 mol% Y₂O₃), wherein a single-molar aqueous solution of ammonium hydroxide is used as a precipitant, then, at the second stage, freshly prepared precipitates of ZrO₂ (3 mol% Y₂O₃) are mixed in a predetermined stoichiometric ratio with saturated aqueous solutions of boehmite, aluminum isopropylate and aluminum nitrate to obtain a final product of 70 wt. % Al₂O₃ – 30 wt. % ZrO₂(Y₂O₃), as a result, suspensions vigorously mixed with a multi-bladed stirrer for 10–20 minutes are formed, and then they are subjected to freezing at a temperature of minus 20 °C to minus 30 °C for a day, freeze drying at a temperature of 25 °C and a pressure of 20 Pa for 5 hours, after which the resultant powder is subjected to a final heat treatment at a temperature of 700–730 °C, process of formation of the crystalline phase of solid solution ZrO₂(3 mol% Y₂O₃) begins at the stage of coprecipitation of zirconium and yttrium hydroxides. At the second stage, as a result of the cryochemical treatment of the suspensions, a partial evaporation of the aqueous component occurs, leading to a decrease in the number of contacts between the particles of the dispersed phase.;EFFECT: avoiding the formation of large agglomerates and the further production of materials with a high specific surface area.;1 cl, 6 dwg, 3 tbl