A Study On The Crystallization Process Of Antioxidant T-501

T-501 is one of the uncolored antioxidants, which is widely used in petrochemical and foodstuff industries. The main problems existing in the production of T-501 in China are the too small crystal size and the asymmetric distribution, which leading to inconveniences in use. The systematic investigation in this thesis will supply data for the further study and the industrial production of T-501.The crystallization process of T-501 belongs to the cooling solution crystallization processes, which uses ethanol as the solvent. In this thesis, the crystallization temperatures of T-501 under different concentrations of ethanol and different feed ratios of solute to solvent were measured. It is shown that the crystallization temperature increases with reduce of the feed ratio or the ethanol concentration. The effects of seeding on the crystallization process of T-501 were experimentally investigated. It is shown that seeding can evidently ameliorate the CSD of the product. When the feed ratio of T-501 to ethanol varies from 1.1 to 0.8 and the ethanol concentration from 65% to 75%, seeding can increase the weight fraction of the product with size bigger than 20 mesh by 20%. When the feed ratio of T-501 to ethanol varies from 1.2 to 0.9 and the ethanol concentration from 80% to 90%, seeding can increase the weight fraction of the product with size between 30 and 40 mesh by 25%. Finally, the technological conditions of the crystallization process of T-501 were optimized by the orthogonal experiments. The CSD of T-501 product can be successfully controlled on the industrial equipment. Products with different CSD demanded by different users can be obtained by varying the operation conditions.