Optimization Of Acetic Acid Process By Methanol Low Pressure Carbonyl Method

Acetic acid,which plays an important role in organic chemical raw materials,is widely used in chemical industry,light industry,textile printing and dying,medicine,agricultural chemicals,electronics,food,rubber and other industries.It performed particularly well in the production of vinyl acetate monomer,therefor can be further used to compound coatings,adhesives and plastic,of course,it also has many other uses,such as the synthesis of purified terephthalic acid,acetic anhydride,propylene/butyl acetate and ethyl acetate,etc.There is no doubt that acetic acid has become an important basic organic chemical raw material in the world in recent years,and its industrialization is also developing rapidly.The synthesis process of acetic acid mainly includes carbonyl oxidation,ethanol oxidation,ethylene oxidation and light hydrocarbon liquid phase oxidation.carbonyl oxidation is the main method of synthesis acetic acid around the world by mixing methanol and carbon monoxide,the reaction was completed by carbonylation under low pressure.With the spread of carbonyl oxidation,high quality and low cost acetic acid are becoming more and more competitive.Based on this,optimization of acetic acid process by methanol low pressure carbonyl method,which can produce low cost and high quality of acetic acid products,has become an important topic in front of the production and technical personnel.The main indexes affecting the quality of acetic acid in the synthesis through methanol carbonylation under low pressure are:propionic acid,reducing substances,and iodine content.In this paper,the influencing factors and control methods of each index and the optimization of the process were studied.First,a new process for the extraction of propionic acid from the waste acetic acid produced by the low pressure carbonylation process of producing acetic acid is explored.It is proposed to be separated and purified by the distillation column to obtain high-purity propionic acid.It improves and optimizes the existing acetic acid production process to build a new set of propionic acid recovery device to reduce the amount of waste acid emissions while the problem of blockage of the weight-removal tower reboiler tubes was solved.TSecond,a new process for the removal of reducing substances in low pressure carbonylation synthesis of acetic acid is developed which gives them greater flexibility of operation.And a new set of aldehyde removal device is created.In the course of operation,we try to add dimethyl ether to the extraction solvent to improve the effect of dehydrochlorination.In addition,a new process for the removal of iodine in low pressure carbonylation process of producing acetic acid is developed.It is proposed to reduce the total iodine content in the acetic acid product through the series operation of two tanks filled with activated carbon and silver loaded packing,Which operating temperature is 30-50?.In this way,a new set of deiodination device was built in which the acetic acid is transported from the tank by the pump pressure into the device which filled with activated carbon and silver loaded packing,The total iodine content was reduced to below 5 x 10^-9,and the mass production of high-quality acetic acid was achieved.A new process is explored,in which silver ion packing is replaced with a renewable non-silver adsorbent,and the effect of deiodization reached the expected target.The device has good operating flexibility and application value.