Preparation Of Propionic Acid By Carbonylation Of Ethanol

Propionic acid is an important chemical raw material,and is recognized worldwide as the optimal food preservatives,widely used in grain,feed and food of antisepsis.Study in depth to ethanol carbonylation one-step synthesis of propionic acid catalyst system and process route is optimized in this dissertation,through self-built single kettle test in micro devices and evaluation process,the main works are as follows:1,Through experimental research,found different degree influence of liquid ratio and reaction conditions on the rhodium catalyst stability and activity,also on the reaction rate.2,For ethanol carbonyl synthesis of propionic acid has a slower reaction rate,this paper discussed through experiment the relationship between reaction rate and the concentration of rhodium catalysts,catalyst promoter iodine ethane concentration,reaction temperature and pressure,also found that the stabilizer and water in the reaction solution could promote the reaction rate.3,Considering these factors for the promotion of carbonylation reaction,response to ethanol carbonyl synthesis of propionic acid fluid,this paper chose originally acetic acid as the solvent for the design of the optimal reaction liquid ratio:iodine ethane,ethanol,acetic acid,water,HI,catalyst,stabilizer alkali metal,etc.The optimal reaction conditions were determined as follows:temperature 170～195℃,pressure 3.0～4.OMpa.Under the condition of the above,ethanol carbonyl synthesis of propionic acid can obtain the highest space-time yield of 2.55 mol·L-1·h-1,and keep rhodium loss rate less than 3.5%.4,On the basis of the study,according to the reaction conditions and solvent acetic acid,catalyst,catalyst recycle requirements,combining with the production experience,the paper designed process for ethanol carbonyl synthesis of propionic acid technology,and optimized the test device.A series of tests have been carried out in the small evaluation device,found that when the ethanol feed rate was too large,could cause ethanol accumulation in the reactions system,thus reduced the rate of reaction.The pressure of evaporator is controlled by 0.1～0.2Mpa,and the temperature 150～155℃,which can obtain higher evaporation rate.Meanwhile the was discussed,which provided a theoretical basis and technical support for the industrialization of propionic acid by one-step carbonylation of ethanol.