Ethanol is produced from biomass by the process of a heated aqueous solution
containing 20 to 40 percent alkali metal hydroxide to break the lignin-cellulose
bond. Then the biomass is heated further to remove carbon dioxide from the cellulose
and lignin to produce a mixture of carbohydrates, modified sodium lignin, micro-cellulose,
lignin-cellulose resinous products and sodium carbonate. Water is added to the
mixture and most of the mixture is water soluble. An acidic salt forming compound
is added to the aqueous solution until a pH of 3-7 is obtained. The lignin is precipitated.
The lignin-cellulose resinous products float to the top and is skimmed off. The
solution containing the carbohydrates and salt is decanted off the lignin and is
concentrated by evaporating off water. The carbohydrates crystalizes from the solution
and the water and salt is filtered off. Water is added to the carbohydrates then
it is fermented to form ethanol. The ethanol is recovered from the water by evaporation.
