Wenderoth, Lind & Ponack
Method for producing L-aspartic acid
 L-aspartic acid is produced by repeating the following respective steps: PA1 (1) a reaction step of producing ammonium L-aspartate from an aqueous solution containing monoammonium maleate in accordance with an isomerization reaction and an enzyme reaction caused by aspartase in the presence of ammonia; PA1 (2) an ammonia-eliminating step of converting substantially all produced ammonium L-aspartate into monoammonium salt by distilling or stripping a reaction solution obtained in the step (1); PA1 (3) a crystallization step of crystallizing L-aspartic acid and producing monoammonium maleate from a solution obtained in the step (2) by adding maleic acid, maleic anhydride or both; PA1 (4) a solid-liquid separation step of separating L-aspartic acid crystals precipitated in the step (3) from a mother liquor containing monoammonium maleate; and PA1 (5) a recycle step of supplying the mother liquor containing monoammonium maleate obtained in the step (4) to the step (1) to be used as a raw material for the reaction. 
Mitsubishi Chemical Corporation
C
C12P
inventional
Yoshiaki Seishi Naoki Naoyuki Norioki
Mori Fujii Kato Watanabe Mine