Study On Synthesis Of Sodium Formate By Sodium Hydroxide Carbonylation In Alcoholic Solvent

Sodium formate is a kind of important chemical raw materials. Currently, the sodium formate is synthesized by the carbonylation reaction of carbon monoxide and sodium hydroxide in aqueous solution. The reaction conditions is relatively harsh and energy consumption is rather high. In this work, to decrease the cost, reduce energy consumption and increase the yield, the carbonylation reaction of carbon monoxide and sodium hydroxide in 95% alcohol solution was studied.The effects of stirring speed, alcohol concentration, molar ratio of sodium hydroxide to carbon monoxide, partial pressure of carbon monoxide and reaction temperature on the reaction rate were investigated. The experimental results showed that the carbonylation reaction in 95% alcoholic solution has faster reaction rate, lower energy consumption and the solvent can be recycled compared with the carbonylation reaction in aqueous solution. Suitable technological conditions were the stirring speed of 300 r/min, the alcohol concentration of 95%, the molar ratio of sodium hydroxide to carbon monoxide of 0.88, the partial pressure of carbon monoxide of 1.5 MPa and the reaction temperature of 80℃. Under these conditions, the yield of sodium formate was 91.71%, and the purity of that approaches to 100%.The solubilities of sodium hydroxide in alcohol solution were studied by balance method. The experimental results showed that the phase separation of solution occurred after adding sodium hydroxide. The split-phase point is related to the concentration of alcohol. In order to understand the effects of split-phase on carbonylation reaction, the relationships between the split-phase point and the concentration of sodium hydroxide, the concentration of alcohol and temperature were studied. The partition coefficient of sodium hydroxide in the two phases was measured. The result showed that if the alcohol solution, whose concentration is lower than 95%, was chosen as the solvent, the phase separation of solution will occur, and the sodium formate was mainly in water phase, which made the effect of alcohol greatly reduced. Therefore, the concentration of alcohol must be higher than 95% if alcohol was selected as solvent used for the carbonylation reaction of carbon monoxide and sodium hydroxide.The solubilities of sodium formate in alcohol solution were studied. The result showed that the solutibility of sodium hydroxide in alcohol solution reduced remarkably with the increase of the concentration of alcohol. If the 95% alcohol solution was chosen as the solvent, the solutibility of sodium formate can be decreased to 0.4515, which means that the reaction product can directly precipitate from solution without evaporation or concentration.The kinetic of carbonylation reaction of carbon monoxide and sodium hydroxide in 95% alcohol solution was studied in a high-pressure reaction kettle. The influence of diffusion and mass transfer resistance on experiment were eliminated. In the following conditions: temperature 318.15～333.15 K, partial pressure of carbon monoxide 1.2～2.4 MPa, stirring rate 500 r/min, the molar ratio of sodium hydroxide to carbon monoxide of 0.88, the alcohol concentration of 95%, the kinetic experiments were carried out. The kinetic equation was obtained after data processing:...