Process for purifying dialkyl diphenylamine

Abstract

The invention relates to a process for purifying dialkyl diphenylamine and belongs to the field of purification of material antioxidants. The process comprises: firstly heating dialkyl diphenylamine crude products to be melt, slowly cooling to the temperature of 60-75 DEG C, keeping the temperature of 60-75 DEG C for 5-10 hours, and discharging mother liquid after melt dialkyl diphenylamine crude products are crystallized to obtain a dialkyl diphenylamine crystal layer; heating the dialkyl diphenylamine crystal layer through a method of gradient increased temperature until the temperature rises to be close to a melting point of the dialkyl diphenylamine, and discharging liquid phase to obtain the purified dialkyl diphenylamine. The quality of the dialkyl diphenylamine purified through the process can meet quality requirements of high-purity-level products, and high-quality dialkyl diphenylamine can be obtained through the process while only a distillation process or a solvent crystallization process can not obtain the high-quality dialkyl diphenylamine. The process is simple in operation, free of consumption of any solvent, high in product yield, good in environmental friendliness and capable of causing no waste water or waste gas.

Description

technical field [0001] The invention relates to a purification process of dialkyl diphenylamine, in particular to a method for preparing high-content dialkyl diphenylamine, which belongs to the field of material antioxidant purification. Background technique [0002] With the development of rubber, plastics, and oil industries, the research and production of antioxidants have attracted more and more attention. At present, whether it is ordinary rubber products, high-grade aerospace lubricants, engine lubricants, etc., there are requirements for high-performance antioxidants, and this requirement is becoming more and more stringent. Therefore, high-performance, high-purity antioxidants are required to meet these requirements. [0003] The above needs can be met by the antioxidant dialkyl diphenylamine. Dialkyldiphenylamine is a kind of alkylated diphenylamine antioxidant. Due to its high purity, high melting point and excellent oxidation resistance, it is widely used in man...

AI Technical Summary

Problems solved by technology

Dialkyldiphenylamine is a kind of alkylated diphenylamine antioxidant. Due to its high purity, high melting point and excellent oxidation resistance, it is widely used in many high-grade rubber products and high-grade oil products. However, due to its production The process is complex, especially the purification process is cumbersome, resulting in low yield and high price

[0004] Dialkyl diphenylamine antioxidants often produce equivalent monoalkyl diphenylamines during the preparation process, and even contain incompletely reacted olefins and diphenylamines, and these monoalkyl diphenylamines, olefins, and diphenylamines are what we call Undesirable, if these impurities are not removed, the final product may be in a liquid state, and may also lead to a very low melting point of the final product, which does not meet the requirements of high-purity anti-oxidant

[0006] 1. The distillation temperature is too high, as high as 250°C, and octylated diphenylamine itself is a heat-sensitive material, which will be partially cracked at high temperature, and the product will change color, thus affecting the final product quality

[0007] 2. The purification efficiency is not high, and the melting point of octylated diphenylamine after purification is only 85°C

Distillation purification method is generally suitable for substances with low boiling point and non-heat sensitivity, but alkylated diphenylamine, as a kind of antioxidant, is easy to change color and decompose at high temperature, which will affect product quality. Therefore, the diphenylamine obtained by distillation purification method Alkyl diphenylamine products are low in content, dark in color and low in quality

However, the solvent crystallization method requires the use of solvents. In the solvent crystallization process, in addition to the crystallization operation unit, centrifugation, drying and solvent recovery units are also required. Therefore, the process is long and the main equipment is large. There are high investment, high energy consumption in the refining process, and Disadvantages such as high solvent loss, large waste liquid discharge, and low product yield