Method for orderly rectifying and separating nitromethane-nitroethane-nitropropane by continuous three towers

Abstract

The invention relates to a method for orderly rectifying and separating nitromethane-nitroethane-nitropropane by continuous three towers, the raw material (an mixed solution of nitromethane, nitroethane,2-nitropropane and 1-nitropropane) is separated through a first continuous rectifying tower at first(B1), the content of the separated nitromethane on the top of the tower can reach over 99.5%, a distillate from the bottom is separated through the second continuous rectifying tower (B2), the content of the separated 1-nitropropane at the bottom of the tower can reach over 99.5%, the once through yields are respectively reach to 89.7% and 91.2%; a distillate from top of a second continuous rectifying tower (B2) is entered into a third continuous rectifying tower (B3) for separating nitroethane and 2-nitropropane, the content of nitroethane can reach above 82.0%, the content of 2-nitropropane can reach above 87.0%. Compared with the multi-times distillation method in the prior art, the separated product content and yield rate of the method provided in the invention are higher than that of the multi-times distillation method.

Description

technical field [0001] The invention relates to a chemical separation process, in particular to a method for sequential rectification and separation of nitromethane-nitroethane-nitropropane in three consecutive towers. Background technique [0002] Low-carbon nitroalkanes are important solvents and intermediates. Nitromethane is mainly used as a solvent and gasoline additive; nitroethane is used in organic synthesis, as a solvent for nitrocellulose and other resins, waxes, fats, dyes, etc. ; Nitropropane includes 1-nitropropane and 2-nitropropane, 2-nitropropane is used as a special solvent for ethylene and epoxy resin coatings, rocket fuel, gasoline additives, etc., and is also used in organic synthesis; 1- Nitropropane is mainly used as solvents and intermediates, jet engine fuels, sprays, etc. (1) As a solvent, it has strong resistance to alcohols, ketones, ethers, esters, dyes, greases, waxes, resins, and synthetic rubbers. Solubility, used together with alcohol is a st...

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Problems solved by technology

Nitromethane has only semi-industrial scale production facilities in China. The production method is mainly nitrite replacement method. The product price varies with the quality, and most of them are exported; It is widely used in the synthesis of pesticides. At present, there is only small-scale production in China, and the content of the product is as high as 99%. Due to the difficulty in production and high risk, some manufacturers have stopped production one after another. There is no large-scale production in China, and they basically rely on imports; Similar to nitroethane, nitropropane has not yet formed a large-scale production in China due to its complicated process and low market demand.

[0004] At present, the separation of nitroalkane mixtures generally adopts multiple distillations to obtain a single fraction. Due to the small difference in boiling point between the low-carbon nitroalkane components, the properties of the components are shown in Table 1, and the distillation method is used for separation. Not only is the operation process complicated , Difficult to control, low product purity, and too many middle distillates at the same time, the yield can only reach 53%

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