Process Control On Continuous Electrochemical Synthesis Of Succinic Acid

With the consciousness of environmental protection enhancing,the demand of poly butylenes succinate(PBS)for the biodegradable plastics,has been increased rapidly.Then the market gap of succinic acid used as the main raw material of PBS is very serious.It is of great pratical significance to study and develop a new production process of succinic acid.Continuous electrolytic synthesis of succinic acid is one of the most effective way to realize the large-scale production.In the actual electrolytic process,the contents of raw material and product in the electrolyte solution show a regular change and fumaric acid as the main impurity should be focused closely.We can detect the content of maleic acid,succinic acid and fumaric acid of various stages in the production process though the HPLC method quickly and efficiently and find its changeful regularity to guide the practical production.In order to obtain the products with a higher quality,this paper explored the generating reason of fumaric acid and changeful regularity mainly and sought the best solution to reduce its content,and confirmed the optimal condition for electrolysis ultimately.In this paper,we find that the segmented electrolysis in different current densities can not only control the content of fumaric acid but also reduce the hydrogen evolution to the largest degree by simulating industrialized electro-synthesis of succinic acid.The experimental data shows that three-segment electrolysis can reduce the content of fumaric acid effectively and obtain high quality succinic acid.When adopted different current densities:10A/dm2,5A/dm2,3.3A/dm2 to electrolysis segmently under constant current,100%theoretic electric quantity and the temperature of 50 ?,the content of fumaric acid would increase at first and decrease later,the amount peak is between 60%~65%electric quantity.In the segmented electrolysis,the best feeding amount of maleic anhydride is 7.35%?8.00%,the average conversion rate can reach 95.77%,reduction yield and current efficiency can reach 86.70%.The content of fumaric acid in the electrolyte would increase obviously when the feeding amount is higher than 8%,and electric quantity should be increased to 1.1 times of the theory so that we can obtain the qualified products.The content of fumaric acid in finished product is about 10 times as much as the content in the final electrolytic solution.In other word,if the content of fumaric acid in the final electrolyte solution could be within 0.01%,we can ensure the quality of succinic acid by controling the content of fumaric in product being within 0.1%.