Method for preparing low-grade aliphatic amine from light alkane through bromination-ammonolysis

Abstract

The invention provides a method for preparing low-grade aliphatic amine from light alkane through bromination-ammonolysis. The method comprises the following steps of (1) bromination reaction, mixing a C1-C4 light alkane raw gas and a bromine gas, catalyzing the mixture in a bromination device through a bromination catalyst, generating brominated alkane and hydrogen bromide; (2) ammonolysis reaction, carrying out ammonolysis reaction on a product in the step (1) and ammonia water in a liquid-phase reaction tank, generating a water solution of an aliphatic amine mixture and an ammonium bromide water solution and controlling pH of a system to be greater than 8 through the ammonia water; (3) separation, separating the ammonium bromide water solution from unreacted light alkane; and (4) electrolytic reaction, pumping the ammonium bromide water solution into a diaphragm electrolysis device, generating bromine from an anode, generating the ammonia water and a hydrogen gas from a cathode, recycling the bromine and the ammonia water separately and storing the hydrogen gas for later use. According to the method, the low-value light alkane can be converted into a high value-added product low-grade aliphatic amine, so that the method is simple and low in cost, and the prepared product is easy to separate and high in purity.

Description

technical field [0001] The invention belongs to the technical field of preparing lower aliphatic amines, and in particular relates to a method for preparing lower aliphatic amines through bromination-ammonolysis of low-carbon alkanes. Background technique [0002] Low-grade aliphatic amines are an important class of fine chemical commodities and basic chemical raw materials, and are widely used in oil fields, petrochemicals, synthetic materials, textiles, pharmaceuticals, pesticides and other industries. At present, there are three main methods for the synthesis of lower aliphatic amines: alcohol-catalyzed amination, halogenated hydrocarbon ammonolysis, and nitrile or nitro reduction. The main raw material of the alcohol-catalyzed amination method is alcohol, and its by-product is water. The production process is relatively clean. Therefore, the total production capacity of the existing domestic low-grade fatty amine plants such as ethylamine, propylamine, isopropylamine, an...

AI Technical Summary

Problems solved by technology

The main raw material of the alcohol-catalyzed amination method is alcohol, and its by-product is water. The production process is relatively clean. Therefore, the total production capacity of the existing domestic low-grade fatty amine plants such as ethylamine, propylamine, isopropylamine, and butylamine is about 80 kt / a , now basically use the relatively low-cost alcohol hydroamination technology route, but alcohol is still a class of high value-added chemical products, and a large amount of grain or cracked petroleum gas will be consumed in the current production process. The price is still relatively expensive; the raw materials for the ammonolysis of halogenated hydrocarbons are halogenated hydrocarbons, caustic soda, and ammonia. The caustic soda is added to the reaction process to cause serious corrosion and pollution, and the by-products are more ammonium chloride and sodium chloride, which cannot be recycled. The cost is high, the conversion rate is low, and the product purity is low; in the nitrile or nitro reduction method, the price of raw materials and reducing agents is high, the oxidation state of the reducing agent is seriously polluted, and the scope of application is narrow

It can be seen that the high cost of raw materials in the prior art and the serious corrosion of the reaction process equipment are a big problem in the production process of low-grade fatty amines, which greatly increases the cost of low-grade fatty amines

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