Study On Preparation Of Hydroxylamine Sulfate And Hydroxylamine From The Acid-catalyzed Hydrolysis Of Ketoxime

As the important chemical products, Hydroxylamine is usually produced and saved in the forms of hydroxylamine sulfate(HAS), hydroxylamine hydrochloride, hydroxylamine nitrate(HAN) and hydroxylamine phosphate. It is mainly used for the production of caprolactam, also widely used in medicine, pesticides, chemical analysis and other fields. Presently, the traditional methods of producing hydroxylamine salt mainly include Rashing method, catalytic reduction method, ion exchange method, neutralization method and the metathesis method, etc. However, in the traditional production process route, there exist some problems which include complex operations, high energy consumption, serious environmental pollution, cumbersome process, etc. Therefore, a new-type production process route, which is environmental friendly and mild, is urgently needed to be developed. In this paper we proposed a new process route which take ammoximation as background, oxime(cyclohexanone oxime, acetone oxime, butanone oxime) as the start material and then obtain hydroxylamine and hydroxylamine salts from the acid-catalyzed hydrolysis of ketoxime. The new production process route has many advantages which include high atomic utilization, mild reaction conditions, simple operation and low energy consumption, environmentally friendly.The research firstly focused on optimizing conditions of the acid-catalyzed hydrolysis reaction of cyclohexanone oxime. The conditions mainly include the molar ratio of acid to oxime when the acid content was low, sulfuric acid concentration and the ratio of heavy to light, reaction temperature in the condition of extractive equipment. The optimized conditions of the hydrolysis reaction are listed as follows. sulfuric acid has concentration of 40% to 60%; the molar ratio of ac id to oxime is 1.0; react at room temperature for 1hr; and the ratio of heavy to light is 1:1.5, reaction temperature is 30℃~40℃.Under the above conditions, the conversion rate of cyclohexanone oxime reaches 44.4% and 51.6% respectively; and the selectivity of hydroxylamine sulfate was 94.4%.Subsequently, the effects of reaction conditions of acetone oxime hydrolysis in acidic solution at atmospheric pressure are studied. The conditions include the molar ratio of acid to oxime, water content, reaction time and reaction temperature. According to the experimental results, The optimum conditions for preparation hydroxylamine sulfate are as follows: the molar ratio of acid to oxime is 1:1, water content is 50 mL,react at 50℃ for 1 ~ 2 hours. The conversion of acetone oxime could reach 32.8% and the selectivity of hydroxylamine get 97.3%.Additionally, the effects of vacuum distillation and rectification technique on the preparation of hydroxylamine sulfate about Acetone and butanone oxime were discussed. It was founded that the vacuum distillation significantly better than batch reactor from the contrast experiments. Then the crystalline and physical analyses of hydroxylamine sulfate were examined. It was showed that the solid crystals are hydroxylamine sulfate, and have a high purity.Finally, the effects of the acid-catalyzed hydrolysis of cyclohexanone oxime for the preparation of hydroxylamine were discussed. By comparing the solid acid catalyst, the amino acid was finally selected as the catalyst. Subsequently, the ratio of solid acid to raw materials, reaction temperature, concentration and reaction time were survived. The results showed that when the ratio of solid acid to cyclohexanone oxime is 1.0,react at the room temperature for 1hr,the conversion of cyclohexanone oxime reached 23.4%, the selectivity of hydroxylamine and cyclohexanone get more than 94% and 92%.