| 摘要 |
The present invention is directed to a method for the production of D,L-aspartic acid. The method comprises reacting an unsatured dicarboxylic acid or anhydride such as maleic acid, fumaric acid, maleic anhydride or mixtures thereof with excess aqueous ammonia at an elevated temperature and pressure for a time sufficient to produce diammonium D,L aspartate. The diammonium D,L aspartate is then neutralized to D,L-aspartic acid; excess unreacted ammonia and various by-products may be recycled and re-used in the method, thereby minimizing waste and cost; i.e. the process is useful for a continuous production process which may be represented conveniently as a schematic block diagram wherein a pressurized reactor (10) receives a reactant admixture from feed tank (12), the reactants being fed subsequently to flash vessel (14) and then precipitator (16) where D,L-aspartic acid is produced upon neutralization, with dicarboxylic acid salts being recovered in a centrifuge (18) and dried in a drier (20). The D,L-aspartic acid may subsequently be used to make polyaspartic acid.
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