Method for continuous gas phase synthesis of oxamide

Abstract

The invention discloses a method for continuous gas phase synthesis of oxamide. In a gas phase reactor, gas phase oxalic acid dialkyl ester and ammonia gas perform ammonolysis reaction under high temperature to generate oxamide product and corresponding fatty alcohol secondary product, and the oxamide product is collected by a cyclone separator. The method uses the gas phase continuous synthesis technology, and solves the defects of long reaction time and poor capacity of intermittent reaction in the existing oxamide preparation technology; by adopting the method, the reaction time is reduced remarkably, the reaction is continuous and steady, the oxalic ester aminolysis conversion rate is high, the quality of the obtained oxamide is high, and continuous steady industrial production of the oxamide is realized.

Description

technical field [0001] The invention relates to a method for synthesizing oxamide, in particular to a method for continuously gas-phase synthesizing oxamide, which belongs to the technical field of oxamide preparation. Background technique [0002] Oxamide is a non-toxic and stable colorless crystal or powder at room temperature. As a urea-formaldehyde slow-acting fertilizer with broad application prospects, its nitrogen content is 31.8%, and its solubility in water is 0.016%. It does not absorb moisture in the air, is non-toxic, and is easy to store. In the process of hydrolysis or biodegradation, ammoniacal nitrogen and carbon dioxide are gradually released, which meets the needs of crops for nitrogen throughout the growth period, and reduces the leaching, volatilization and loss of nitrogen. The loss caused by denitrification improves the utilization rate of chemical fertilizers, reduces the frequency of fertilization, and saves manpower and time. Its advantages as a slo...

AI Technical Summary

Problems solved by technology

This method can be divided into Degussa method, Sagami method, Asahi Kasei method and Hoechat method. The difference between the four methods is that the oxidant, catalyst and process are different. The disadvantage of this preparation method is that hydrocyanic acid is highly toxic and costly. There are reports of industrialization;

[0005] (2) Pyrolysis method, that is, ammonium oxalate or urea oxalate is used for pyrolysis to obtain oxamide, but this method is costly and has no practical value, and there are few studies at present

[0006] (3) Ammonolysis method of dialkyl oxalate (US6348626, US5393319, CN102267921A), in which dialkyl oxalate reacts with ammonia gas under the dissolution of corresponding fatty alcohol to generate oxamide and corresponding fatty alcohol. The method is usually a gas-liquid phase batch reaction, which cannot achieve continuous and stable operation

But in the above-mentioned preparation technology of dialkyl oxalate aminolysis method to prepare oxamide, there are problems such as reaction temperature is low, reaction time is long and reaction can not carry out continuously, because need fatty alcohol to dissolve dialkyl oxalate, so reaction temperature is generally lower , at the same time, the reaction is a gas-liquid phase contact reaction, the reaction time is usually about 20 hours, and the reaction needs to be carried out in a batch reactor, which cannot run continuously and stably, thus failing to meet the requirements of industrial production

Images