Polyacrylamide belongs to the organic macromolecule polymers and it is widely used in the fields of oil exploitation, water treatment, mineral separation and papermaking and so on. Polyacrylamide is aggregated by acrylamide monomer.
Therefore it is self-evident that acrylamide is very important in the process of polyacrylamide production. Acrylamide uses in textile, printing and dyeing auxiliaries, etc.
The production technology of acrylamide - polyacrylamide monomer, or any other production methods, all adopt the acrylonitrile as the raw material. The acrylonitrile turns to be acrylamide mononer rough-wrought products by hydrate formation with the help of catalyst. After being refined, acrylamide monomer becomes the raw material to generate polyacrylamide.
The production technology of acrylamide monomer is classified into two categories: chemical method and biological process according to the types and development history of reaction catalyst.
The first generation technology of chemical method is the sulfuric acid catalytic hydration technology. Its disadvantage are the low convertion rate of acrylonitrile, low product yield of acrylamide, low by-product yield, which were a burden to refining. Additionally, the high causticity of sulfuric acid results in high cost of equipment, increasing the production costs.
The second generation technology of chemical method is the binary or ternary raney copper catalyst. Its disadvantage is that there exists the copper ion exchange in the process of biological production of acrylamide.
Thus metallic copper ion is introduced to affect the polymerization in the finished product, which increases the refining costs in the post processing.
The IUPAC name of acrylamide is prop-2-enamide. The biological process takes biological enzymes as catalyst and prepares the hydrated solution with acrylonitrile, water and biocatalyst. After the catalytic reaction the dead catalyst is separated out and the acrylamide product comes into being.
Comparing to the copper-catalyzed hydration method, acrylamide has its characters. It has exteremely high convertion-per-pass of acrylonitrile. It greatly simplifies the operation of separation and refinement for it has no needs to exchange ion and separate copper.
The biological process produces high concentration products without any concentrage operation, which is suitable to produce the polyacrylamide, the high viscosity and ultrahigh relative molecular weight matter.
The biological process of acrylamide has developed into the following three technical skills so far:
(1) The biological process of membrane technology:
The procedure includes microbial culture and bacteria suspension preparation. Take the free bacteria as biological catalyst to make hydration reaction of acrylonitrile. After reaction the hydration fluid of acrylamide comes into being.
It features that it washes and purifies the thallus in the fermentation liquor to prepare the bacteria suspension with micro-filtration membrane as well as separate the hydration fluid of acrylamide and biological impurities with ultrafiltration membrane.
This skill of producing the acryloyl glue obviously improves the production efficiency and thallus utilization. In addition the content of biological impurities in the hydration fluid products decreases and the acrylamide has good quality and high purity.
(2) Biological cyclic catalyst:
Produce the corynebacterium propinquum with nitrile hydratase or its mutated strain cells, and catalyze the acrylonitrile to hydrate into acrylamide, which produces the high purity acrylamide.
(3) The biological catalyst, washed by acrylate aqueous solution:
First wash the biological catalyst with acrylate aqueous solution and apply it into conversion reaction to prepare the acrylamide.
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