Production route of fumaric acid

Chemical synthesis

Process flow: benzene or butene and air, catalytic oxidation, hydrolysis, concentration, crystallization, finished products.

1.Maleic acid isomerization method

Benzene or butene (80%) and excess air are absorbed by the circulating liquid field in a fluidized bed or fixed bed reactor to produce maleic acid. Under the action of thiourea catalyst, maleic acid is heated to 145-260°C through isomerization reaction to generate fumaric acid, which is then cooled, filtered, washed with hydrochloric acid, dried and crushed to obtain finished products.

The preparation of the raw materials of this method is generally based on the benzene method and the n-butane method, and the yield is about 93.0%. It has the advantages of convenient transportation, no corrosion of equipment, and low dosage. The disadvantage is that it requires petroleum resources and the process conditions are harsh.

2.Furfural oxidation method

Using furfural and water as raw materials, add 58.5g of KClO3 powder, an appropriate amount of V2O5/MoO3 (0.8:1) catalyst and 100mL of 0.5mol/L hydrochloric acid solution in a 250mL beaker. Stir continuously to 110°C, add 20mL of furfural dropwise, and add After that, let it continue to react for 2h. Then it was cooled and filtered to obtain crude fumaric acid.

The yield of this method is 83.0%. The advantage is that there is no industrial pollution, and the by-product KCl can be recycled as agricultural fertilizer. The disadvantage is that the production cost is high.

Fermentation

Using liquid paraffin as raw material and Rhizopus nigricans as a strain for submerged fermentation for 80-90 hours, and then undergoing multiple steps such as separation, decolorization, crystallization, and drying, the fumaric acid product is obtained. The conversion rate of liquid paraffin is about 50%, and the extraction rate is above 50%. In addition, it can also be produced by fermenting raw materials such as yam and starch.