Method of manufacturing succinic acid and ammonium succinate solutions

Succinic acid and its derivatives are widely used as raw materials in the manufacture of foods, perfumes, cosmetics, and medicines. Furthermore, succinic acid(cas:110-15-6) has been recently used in monomers of biodegradable plastics. The succinic acid used in these applications is produced by a petrochemical method. Alternatively, the production of succinic acid by fermentation has been recently investigated using carbohydrates of plant origin as raw materials.

When producing succinic acid(cas:110-15-6) by a fermentation method, the culture pH should generally be maintained at around neutral, so that microorganisms can exhibit the necessary and sufficient activities. As a neutralizing agent, calcium hydroxide, sodium hydroxide, magnesium hydroxide, ammonia, calcium carbonate, sodium carbonate, magnesium carbonate and ammonium carbonate, etc. can be used. As a result, the corresponding succinic acid(cas:110-15-6) salts can accumulate in the culture solution.

Among the succinic acid(cas:110-15-6) salts, it is known that calcium succinate has a low solubility, and can precipitate as crystals into the culture solution (JP62-294090A). Usually, the culture solution contains a mixture of raw materials for fermentation, such as sugars, various additives, such as nutrients for the chosen microorganism, and by-products produced by the metabolism of microorganism, etc. Because calcium succinate is easily removed from the culture solution due to precipitation of the crystals, purification of succinic acid(cas:110-15-6) can be simple. Furthermore, since further purification methods to isolate the succinate crystals, such as concentration, are unnecessary, the precipitation of calcium salt is advantageous from the viewpoint of energy consumption.

A typical method of separating succinic acid(cas:110-15-6) from succinate salts is to lower the pH until free succinic acid(cas:110-15-6) is generated by adding an acid, such as sulfuric acid. For calcium succinate, a method of obtaining succinic acid(cas:110-15-6) by using sulfuric acid is known (JP3-30685A). However, this method has limitations since sufficient amounts of calcium sulfate do not precipitate as a by-product.

To separate succinic acid(cas:110-15-6) from succinates without using acid, electrodialysis has been proposed (JP2-283289A). Since bases which separate from succinic acid(cas:110-15-6) during the purification process are reused as neutralizing agents in fermentation, by-products are not produced. However, this method is limited to the succinic acid salts with monovalent bases, such as sodium succinate and ammonium succinate. For calcium salt, this method is unsuitable due to the precipitation and build-up of debris on the membrane used for filtration. For these reasons, studies using calcium compounds as neutralizing agents have not been conducted in recent years.

Alternatively, when succinic acid(cas:110-15-6) is obtained from ammonium succinate using sulfuric acid, ammonium sulfate is produced as a by-product. A method of preventing the generation by-product salts was finally proposed by pyrolyzing the produced by-product ammonium sulfate at 300° to produce ammonium hydrogen sulfate and ammonia, and then reusing them in the process (JP2001-514900A).

Ammonium succinate can accumulate in the culture solution by using ammonia, or the like, as a neutralizing agent in the fermentation process. However, it is known that ammonia is not the most efficient neutralizing agent for producing succinic acid(cas:110-15-6), and from the viewpoint of productivity and yield during fermentation, magnesium compounds can be effective (WO2005/026349A).