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Talking about the process of DMF


There are probably two ideal methods for the production of dimethylformamide DMF. The two-step methanol dehydrogenation process is a new one-step process for the synthesis of methyl formate developed by the Southwest Research Institute of Chemical Industry of the former Ministry of Chemical Industry. The process is more complicated and the yield is low. Among them, the most widely used method in China is the one-step method.
The one-step method consists of dimethylamine and carbon monoxide in sodium formate as a catalyst at a temperature of 50-100 degrees. Direct synthesis of DMF under the pressure of 1Mpa. This method has low raw material prices, wide sources, advanced production technology, energy saving, high product purity, more than 99%, suitable for large-scale continuous production, and most large-scale enterprises in the United States, Japan and my country adopt this method. The main raw materials of the one-step process are synthetic ammonia, industrial methanol and carbon monoxide. At present, the domestic DMF production industry giants such as Zhejiang Jiangshan, Hualu Hengsheng, Luxi Chemical, etc. all adopt the one-step process.
The one-step process DMF reactor is a bubble reactor. The dimethylamine and catalyst solution are measured by a metering pump and then sent to the reactor. The carbon monoxide gas is sent to the reactor after the mixing ejector. Under the action of the catalyst, the carbon monoxide and dimethylamine undergo a gas-liquid reaction to form DMF.
The catalyst and salt by-products are removed from the reaction liquid through an evaporation-filtration system. The filtered solid is regularly sent to the boiler room to be mixed with coal and burned; the liquid phase stream is completely vaporized in the evaporator and then enters the light removal tower. The light component removed from the top of the light removal tower is the dimethylamine/methanol mixture, which flows into the circulation tank by itself, and then circulates to the reactor via a pump: the kettle liquid enters the vacuum tower. The vacuum tower is operated under vacuum, and the heavy components discharged from the bottom of the tower are collected in the heavy component storage tank, and the heavy components are regularly sent to the processing plant to recover DMF; the DMF distilled from the top of the tower is condensed and sent to the gas stripping tower. Dry high-purity nitrogen enters from the bottom of the gas stripping tower, and contacts DMF in the gas-wave two-phase countercurrent contact with DMF in the gas stripping tower to further remove the dimethylamine dissolved in DMF. Part of the tower kettle liquid is circulated to the top of the tower, and part of it is cooled and sent to the DMF intermediate tank. After passing the test, it is pumped to the DMF product tank area. The gas discharged from the top of the gas stripping tower is condensed by the condenser and the tail condenser, the condensate is returned to the gas stripping tower, the non-condensable gas is discharged at high altitude through the water sealing tank, and the waste water is sent to the sewage treatment station.