There are mainly three industrial processes for producing n-butanol: fermentation, propylene carbonyl synthesis, and aldolaldehyde condensation.
1. Fermentation method The raw materials such as grains, cereals, dried hawthorn or molasses are crushed and water is added to make the fermentation broth. After sterilization by high-pressure steam treatment and cooling, the pure acetone-butanol strain is introduced and fermented at 36-37°C. . The gas produced during fermentation contains carbon dioxide and hydrogen. The fermentation broth contained ethanol, butanol, acetone, and the usual ratio was 6:3:1. After distillation, butanol, acetone and ethanol can be obtained separately, and can also be directly used without isolation as a total solvent.
2. The carbonyl synthesis method is Reppe Process. Carbon monoxide and hydrogen are obtained from coke gasification, and oxo synthesis of propylene and isobutyraldehyde is carried out with propylene in the presence of high pressure and cobalt or lanthanide catalysts. Fractionation after hydrogenation Get butanol.
3. Aldol Aldolization By the condensation of two molecules of acetaldehyde, crotonaldehyde is obtained by condensation and dehydration. Crotonaldehyde is hydrogenated at 180° C. and 0.29 MPa to produce n-butanol in the presence of nickel-chromium catalyst. The by-product n-butanol can be used to produce iso-octanol. Alcohol aldol condensation yields 98.5% of 1t butanol, 1300kg of acetaldehyde, and 674kg of hydrogen.