Adn Adiponitrile is among the indispensable resources for the manufacturing of nylon 66. Innovation is still in a state of high syndicate. Currently, there is no commercial manufacturing plant for Adn Adiponitrile in China, as well as the need for Adn Adiponitrile has actually been mostly depending on imports. With the fast growth of my country’s nylon 66 sector, the need for the intermediate hexamethylene diamine for the raw material adiponitrile has actually boosted. It is estimated that in 2010 The annual outcome will certainly get to 200,000 t/a. Today, the process routes of several widely known large firms on the planet for the manufacturing of adiponitrile primarily include acrylonitrile (AN) electrolytic dimerization technique, adipic acid (ADA) catalytic ammoniation method and butadiene (BD) technique. There is a lactam deterioration as well as rehydrolysis process of Japan Toray Firm.
1. Electrolytic dimerization of acrylonitrile
The main reaction equation of acrylonitrile electrolytic dimerization to produce adiponitrile is:
The production process was successfully developed by Monsanto Company in the 1960s, and gradually developed from diaphragm electrolysis to non-diaphragm electrolysis. Diaphragm electrolysis method is divided into solution method and emulsion method. Monsanto Company adopted the solution method when it was first developed. Preparation of Adn Adiponitrile. Later, Japan’s Asahi Kasei Company developed the emulsion method on the basis of Monsanto Company. Acrylonitrile is emulsified in the catholyte with the help of emulsifier polyvinyl alcohol, electrolyte and other substances for dimerization.
The non-diaphragm electrolysis method, represented by VCB (Belgium Union Chemical Company), is a direct electrosynthesis process, and its electrolyte is an emulsion; considering that acrylonitrile does not participate in the anode reaction, the diaphragm is cancelled. BASF also uses a special capillary gap electrolytic cell to establish a non-diaphragm electrolytic cell. The electrolytic cell is composed of multiple graphite plates overlapping. The raw material propylene of the acrylonitrile hydrogenation dimerization method is cheap and easy to obtain, with high reaction selectivity and minimal pollution. If the process cost and factory investment are further reduced, the economic competitiveness of the method can be improved; however, this process route uses high toxicity , The highly corrosive raw material acrylonitrile is not an ideal process route.
2. Adipic acid catalytic ammoniation
The main reaction equation of adipic acid catalytic ammoniation method is:
This production process route was successfully developed by the French Rhone Planck Company in the late 1960s. This method is divided into gas phase method and liquid phase method. The gas phase method adopts boron phosphate catalyst, and the reaction temperature is 300 ~ 350 ℃. It will decompose when it is chemical, so the selectivity is only 80%. With transient gasification and fluidized bed reactors, selectivity can be increased to 90%.
The liquid phase method is to aminate the molten adipic acid at 200-300 °C in the presence of a catalyst (such as phosphoric acid). Pure adiponitrile can be obtained by dehydration, weight removal, chemical treatment and vacuum distillation of the reaction product. Because this process route uses another main raw material adipic acid for producing nylon 66 salt, the process route is long, the cost is high, and it is not an ideal process route, but compared with the acrylonitrile method, it is still an important production process.
3. Butadiene method
The main reaction equation of the butadiene method is:
Butadiene method (BD) is divided into butadiene chlorination cyanation method and butadiene direct cyanation method. The butadiene chlorination cyanide method was first developed by DuPont in the early 1960s. The process is complicated, corroded seriously, and the investment is large. It has been eliminated. In the early 1970s, DuPont developed a method for direct cyanation of butadiene without chlorine. The 1,3-butadiene and hydrocyanic acid were reacted in the liquid phase at 100 °C in the presence of a catalyst to generate pentene nitrile. Isomer mixture; after separation and isomerization of isomers into linear pentene nitrile, it is then added with hydrocyanic acid to form adiponitrile, which reduces the cost of raw materials by 15% and saves energy by 45% compared with the chlorination method.This method has two sets of production units in the United States, and in 1974, in the Chalampa region of France, a joint venture with the Rhone Planck Company built the Butachemic Co. Ltd. A set of production units that are cuss route has cheap and easy-to-obtain raw materials, short route, no pollution, low energy consumption and low cost, and is currently the most advanced, ideal and important production process route.
4. Caprolactam degradation hydrolysis method
Toray Company of Japan used waste caprolactam as raw material to develop a process route of degrading caprolactam and then hydrolyzing it to produce adiponitrile. It focuses on the recycling of waste raw materials, which is a good development idea, and the production cost has also been reduced. The key is that the lack of raw materials cannot be produced on a large scale.