Method for preparing high-purity acetonitrile from acetic acid and ammonia by two steps

Abstract

The invention discloses a method for preparing high-purity acetonitrile from acetic acid and ammonia by two steps, which comprises the following steps of: (1) neutralizing acetic acid and ammonia to generate ammonium acetate; (2) mixing aqueous solution of ammonium acetate and gaseous ammonia, preheating, and making the mixture enter a fixed bed reactor filled with a catalyst aluminium oxide for reaction to generate acetonitrile-containing mixed gas; and (3) continuously refining the mixed gas to obtain the acetonitrile. The 70 to 80 weight percent acetic acid is taken as a raw material, and the produced acetonitrile product has the advantages of less varieties and low content of impurities, high purity of over 99.9 percent, simple separation process, shorter flow, low energy consumption only about 40 percent of that of a byproduct method in unit product, and lower cost. The separation process is a physical separation method, and avoids generating a great amount of wastewater and waste gas in the chemical treatment process of the byproduct method. Meanwhile, a synthesis method is adopted, so the limitation that the yield is limited by a main product can be radically eliminated.

Description

Technical field [0001] The invention relates to a method for preparing acetonitrile using acetic acid and ammonia as starting materials. Background technique [0002] Acetonitrile is an important fine chemical intermediate product and chemical solvent. It is an intermediate for the synthesis of medicines and fragrances, such as the active medium solvent for the synthesis of vitamin B1, vitamin A, cortisone and amino acids, carbon amine drugs and their intermediates. Intermediate solvent can replace chlorinated solvent; it is the raw material for the manufacture of triazine nitrogen fertilizer synergist; used as the denaturant of acetic acid; in organic synthesis, it is used to prepare 2-methylpyridine, triazine and ethylamine , Dipropionitrile, imidazole, propylene diacetonitrile, etc. Acetonitrile can be used as an extractant for butadiene and isoprene, a spinning flux for synthetic fibers, and a solvent for special coatings such as vinyl coatings; used in the petroleum industr...

AI Technical Summary

Problems solved by technology

[0003] At present, the industrial acetonitrile products are all produced by the acrylonitrile by-product method, the output is limited (about 2.5% of the acrylonitrile output), and the quality is difficult to guarantee

Such as Chinese patent, application number CN 03112026.1 disclosed "method for synthesizing high-purity acetonitrile by ammoxidation of acetic acid", describes a kind of method for synthesizing high-purity acetonitrile by ammoxidation of ethanol, is the method for synthesizing acrylonitrile with reference to propylene ammoxidation, with ethanol, ammonia , Oxygen as raw material, using fluidized bed catalytic reaction technology, the process consists of three parts: reaction process, recovery process and refining process, because the process is too long, the investment is too large and the by-product of highly toxic hydrogen cyanide gas, so No industrialization report has been seen so far

[0004] Due to the special properties and excellent properties of acetonitrile, it is more and more widely used in chemical, pharmaceutical and pesticide industries. However, due to the current extreme shrinkage of the acrylonitrile market, the acetonitrile market is in a serious shortage. At the same time, because of the first acrylonitrile The continuous negative growth of acrylic fiber, a major market use, and the continuous decline in future market demand will exacerbate the contradiction between the supply and demand of its by-product acetonitrile. Therefore, it is urgent to develop a process route for the production of acetonitrile by chemical synthesis to meet the needs of relevant parties.