Patent GB-574094-A (GB)
Title: Improvements in or relating to the recovery of butylene glycol from carbohydrate fermentation mashes
IPC: C12P7/18
Filed: 1943-05-06
Abstract: 2 : 3-Butylene glycol is recovered from a liquid concentrate of a carbohydrate fermentation, in which the butylene glycol is formed as one of the major products of the fermentation and in which no substantial amounts of glycerol is formed, by a process which includes the steps of treating the said concentrate with an alkaline earth metal oxide or hydroxide to form a flowable cream containing an undissolved excess of alkaline earth metal hydroxide, mixing the resulting cream with an alcohol of the saturated aliphatic monohydric series that is miscible with water in all proportions, in amount and concentration sufficient to precipitate substantially the whole of the precipitable impurities, separating off the alcoholic liquid from the solid phase and recovering the butylene glycol from the alcohol extract. The amount of water present during the above treatment is advantageously not more than the combined weight of butylene glycol and non-volatile impurities.  Ethyl alcohol is a suitable water miscible alcohol.  The concentrate and the flowable cream should be used at a temperature of 40-80 DEG  C. to maintain it in a fluid state.  The alkaline earth may be used in the form of a fine dry powder but preferably is made into a cream with a portion of the alcohol or a little water.  It is then intimately mixed with the fermentation residue concentrate and the resulting cream is agitated with the alcohol until the particles of precipitated impurities have hardened.  Alternatively the cream of concentrate and alkaline earth may be extruded through fine orifices into the alcohol.  After allowing the precipitated impurities to settle, the extract is decanted off or separated from the impurities by a mechanical classifier or other means.  The alcohol is evaporated from the alcoholic extract and the crude aqueous butylene glycol solution obtained may be further concentrated.  It may then be purified further by fractional distillation after the addition of a small excess of caustic soda or by extraction with a water immiscible volatile organic nitrogen base such as aniline, separation of the resulting extract from the insoluble residue and recovery of the butylene glycol by further extraction from said extract with water and subsequent fractional distillation. Acetylmethylcarbinol, produced in the fermentation is easily eliminated by the fractional distillation.  The amount of alkaline earth to be employed depends on the amount of impurity present; for a liquid concentrate of carbohydrate fermentation containing about 25 per cent of water, 8-12 per cent of alkaline earth, calculated as lime, should be added.  The dried solid residue may be employed as a fertiliser.  An example describes the recovery of butylene glycol from a fermentation concentrate derived from sucrose employed in the form of molasses or cane syrup.  Other carbohydrate materials mentioned are crude cane sugar, and grain or beet molasses, the carbohydrate mashes being inoculated with appropriate organisms, e.g. aerobacter, aerobacillus, or aeromonas.