Determination Of Formic Acid In Cyclohexane From LiaoYang Petrochemical Company's Alcohol-ketone Equipment

The new Adipic-acid equipment of LiaoYang Petrochemical Company is the first product line which is approved by China state on the policy of thriving on the northeast old industrial bases. The product line includes three suits which are cyclohexane,Alcohol-ketone,Adipic-acid equipment respectively. Alcohol-ketone is the most important mid-equipment of the product line.Since October, 2004, because the corrosion reason of the equipment , Alcohol-ketone equipment had been ran unsteadily all through. Analysis of the scene revealed that the formic-acid in cyclohexane was the reason of the equipment corrosion . Because the measurement system of the formic acid in cyclohexane hadn't been built in LiaoYang Petrochemical Company, the law of formic acid couldn't be found in time, technological parameters couldn't be adjusted to operate the equipment steadily. How to measure the content of formic-acid in cyclohexane is the key link to prevent the equipment from being corrupted.In this paper, based on collecting literature and experiment study a gas chromatography method to measure the content of formic-acid in cyclohexane has been put forward. Sebacic-acid/GDX103 is chosen as packed column (2mx2mm), some parameters such as velocity of flow,temperature of gas and chromatography apparatus were discussed, and the best experimental conditions were provided.The best experimental condition can be described as following: temperature of carburetor room isl50℃, temperature of detector is 150℃, column box temperature is 110℃, bridge current is 135 mA, hydrogen is chosen as carrier, flow velocity is 50 ml/min, sebacic-acid/GDX103 is chosen as packed column (2m×2mm), TCD is used as detector. The detection limit of this method can reach 1×10^-4%, recovery ratio of adding standard g was about 96～105%, the square of the opposite standard deviation was less than 4.2%. The linear relation was better between 0～10%.In this paper, the comparison experiment between the ultraviolet absorption spectroscopy and the gas chromatography method had been proceeded. The result demonstrated that the measurement of the ultraviolet absorption spectroscopy was not suit to the Lang-Bill law, it couldn't measure the content of the formic acid accurately.The practical application of the gas chromatography method shows that the content of the formic acid in cyclohexane can be measured exactly, and the need of the middle control analysis can be satisfied. This is very important to prevent the corrosion of equipment for LiaoYang Petrochemical Company.