Cause Analysis Of Acetaldehyde Polymerization And Measures To Restrain The Polymerization

In the process of synthesizing vinyl acetate with acetylene and acetic acid, the quality of the recovery of Sichuan Vigny is very unstable, often prone to the polymerization reaction, resulting in a small amount of melamine and four poly acetaldehyde. At the same time in the process of storage and transportation of acetaldehyde, it often occurs in the process of the formation of the melamine, which can cause the temperature and pressure of the storage tank to rise and plug the pipeline. In order to protect the safety of acetaldehyde production and sales, to prevent the occurrence of accidents causing personal injury and property damage, the study through experimental means to find the cause of acetaldehyde and the effective inhibition of the polymerization of the polymerization.According to the low boiling point of acetaldehyde, polymerization reaction is exothermic characteristics by closed three mouth flask as the reaction vessel and placed in the constant temperature water bath box for reaction, to avoid the volatilization of acetaldehyde, easy temperature control, convenient feeding and sampling multi purpose.A gas chromatography method was used to analyze the mixture of acetaldehyde and acetaldehyde in the experimental system. The conditions of gas chromatography were established. The 0.06 MPa 0.25 mm was used as the quartz capillary column with 30 m * m * 0.3 SE-30. The temperature of the sample was 160, the temperature of the hydrogen flame detector was 160, the air pressure was 0.10 MPa, the hydrogen pressure was 0.6MPa.In the experiment, the organic acid, such as hydrochloric acid, sulfuric acid, formic acid and acetic acid, was chosen as the catalyst, and the catalytic effect of the catalyst on the polymerization was investigated. The results showed that the organic acids such as hydrochloric acid, sulphuric acid and formic acid had a catalytic effect on the polymerization of pure acetaldehyde, but acetic acid had no catalytic effect on the polymerization of acetaldehyde. The higher the catalyst concentration, the stronger the catalytic effect of the acetaldehyde polymerization, but the higher the concentration of the catalyst to a certain extent, the reaction of acetaldehyde polymerization will tend to balance. The catalytic effect of inorganic acids is much stronger than that of organic ac-ids, but the effect of hydrochloric acid is stronger than that of sulfuric acid.The effect of reaction temperature on the catalytic polymerization of acetaldehyde was also determined. The increase of the reaction temperature is beneficial to the formation of the melamine. In the catalytic action of hydrochloric acid, the rate of the reaction of acetaldehyde is increasing with the increase of temperature.Experimental study of the inhibitory effect of ammonium acetate, ammonium citrate and NaOH of these three substances on polymerization of acetaldehyde. The results show that for actual production of substandard acetaldehyde system. The strongest inhibitory effect of ammonium acetate, NaOH is the weakest, and vice versa for the polymerization of acetaldehyde with hydrochloric acid as catalyst system, the strongest inhibitory effect of NaOH, and lemon acid ammonium weakest.