The preparation methods of n-butanol are as follows.
In the past, butanol was obtained by hydrolysis and fermentation using potatoes, grains or sugars as raw materials. The product obtained from the fermentation broth contains about 54.8% to 58.5% of n-butanol, 30.9% to 33.7% of acetone, and 7.8% to 14.2% of ethanol. With the development of petrochemical industry, the fermentation method is gradually eliminated. The reaction equation is as follows: (C6H10O5)n[n(H2O)]→[strain]n-C6H12O6[fermentation]→CH3COCH3+C4H9OH+C2H5OH
The obtained fermentation broth is then fractionated to obtain acetone, ethanol and n-butanol respectively.
Using acetaldehyde as a raw material, add dilute alkali solution, the temperature is below 20 ° C to obtain 2-hydroxybutyraldehyde, when the reaction reaches 50%, it will be terminated, the alkali is neutralized with acid, the unreacted acetaldehyde is recovered, and 2-hydroxybutyraldehyde is extracted at the bottom of the tower. Hydroxybutyraldehyde is dehydrated at 105-137°C with acid catalysts such as sulfuric acid and acetic acid to form crotonaldehyde, and then hydrogenated with copper complex catalyst at 160-240°C to obtain crude n-butanol and butyraldehyde, which are rectified to obtain finished products. CH3CH=CHCHO+H2[catalyst]CH3CH2CH2CHO+CH3CH2CH2CH2OH propylene oxo synthesis
Use propylene, carbon monoxide and hydrogen to react on the catalytic bed, the catalyst is zeolite adsorption of cobalt salt or fatty acid cobalt, the reaction temperature is 130 ~ 160 ℃, the reaction pressure is 20 ~ 25MPa, the reaction generates n-butyraldehyde and isobutyraldehyde, after refining Distillation for separation, catalytic hydrogenation of n-butyraldehyde to obtain n-butanol. CH3CH2CH2CHO+H2→CH3CH2CH2CH2OH
It is also possible to use a low-pressure method to synthesize butanol from propylene, carbon monoxide and water in one step. The reaction temperature is 100-104 °C and the pressure is 1.5 MPa. The mixture of pentacarbonyl iron, n-butylpyrrolidine and water is used, but the single-pass conversion rate of propylene is relatively high. Low, only 8% to 10%. Reaction equation: CH3CH=CH2+3CO+2H2O→n-C4H9OH+2CO2