REGULARITIES OF BAYERITE-STRUCTURED ALUMINIUM HYDROXIDE FORMATION DURING PRECIPITATION

Based on published data and experimental studies of formation regularities of aluminium hydroxide, a reproducible technique for synthesis of bayerite-structured aluminium hydroxide by precipitation was developed as a part of the creation of preparation technology of chromia-alumina dehydrogenation catalyst. A possibility of synthesis of high purity bayerite (above 90 wt.%) with different particle sizes depending on synthesis conditions was shown. A correlation between dispersion of the sediments and synthesis temperature was shown, the optimal precipitation temperature – which allows obtaining bayerite with a sufficiently large particle size and high purity – was found. Based on the experiments, a fundamental difference between technologies and products of precipitation by sodium hydroxide and aqueous ammonia was shown. The influence of duration of precipitation stages on the properties of sediments is analyzed from the standpoint of theory of relative supersaturation