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Acrylamide production methods
Edit this paragraph production technology in 1954, American Cyanamid Company first developed legal sulfate production technology, the industrial production. Since then, acrylamide production process has undergone two changes: the mid-invented the copper-catalyzed hydration of the 1970s, mid-1980s to develop a microbial production process. Sulfuric acid hydration process is complex, copper catalytic hydration reaction due to the addition contain small amounts of by-products; Microbial production of monomers due to low impurity content, high activity, particularly suitable for producing ultra-high molecular weight polyacrylamide, and therefore subject to respected. Relative to the microbiological method, legitimate part of the traditional methods of legal and copper sulfate catalytic water.
Traditional methods sulfate hydration prior acrylonitrile at below 100 ℃ hydrolyzed to acrylamide sulfate, and then neutralized to give acrylamide (AM). By the beginning of the acrylamide homo- prepared nonionic polyacrylamide, relatively simple products. Soon developed a partially hydrolyzed with alkali (after hydrolysis) of anionic polyacrylamide.
Legitimate use of copper in the catalytic hydration of acrylonitrile to hydration in the presence of a copper-based catalyst prepared by the reaction of acrylamide, the method comprising the reaction system or a salt thereof having an active methylene group and an acidic group in one molecule appears , then the anionic acrylamide-containing solution with a weakly basic or a medially basic exchange resin. In the above hydration reaction, the formation of impurities is suppressed, and catalyst activity was not affected, resulting acrylamide may be used to manufacture the water-soluble high molecular weight and good flocculant.
Copper-catalyzed hydration of acrylonitrile can also be handled by at least two purification steps, the first of acrylonitrile and strong acid cation exchange resin, then or in contact with the activated carbon and resin having a primary or secondary amino group of. Finally The resulting acrylonitrile is hydrated in the presence of copper-based catalyst. Even with normal-quality acrylonitrile, the method can also be made high-quality acrylamide, and can further make a polyacrylamide with good water solubility.
Legal disadvantage is the need to recycle copper-catalyzed water acrylonitrile and separation of copper, waste of resources and energy; while many side effects, is not easy to control, product purity is not high.
Microbiological method microbiological method acrylonitrile, water and immobilized biocatalysts deployment into hydration solution, after separating the spent catalyst catalytic reaction can be obtained acrylamide product. Compared with the traditional legal copper-catalyzed water, its features are: reaction at normal temperature and pressure, the device is simple, safe operation; high-way conversion rate, without separation and recovery of unreacted acrylonitrile; specificity of the enzyme to make high selectivity No side effects. When using J-1 strain, the reaction temperature is 5-15 ℃, PH value of 7-8, the reaction zone acrylonitrile concentration of 1% -2%. Acrylonitrile conversion was 99.99%, the selectivity of 99.98% acrylamide, an acrylamide reactor outlet concentration close to 50%; the amount of inactivated enzyme catalyst is discharged outside of the system is less than 0.1% of the product; without copper separation section, without ion exchange processing, the separation and purification operations greatly simplified; high product concentration, without mention rich operation, the whole process is simple, less investment in equipment, high production cost, which will help small-scale production.