Patent GB-653834-A (GB)
Title: Improved process for the synthesis of hydrocarbons
IPC: C07C29/16
Filed: 1947-05-20
Abstract: Oxygenated hydrocarbons are segregated from vaporous products obtained by the hydrocarbon synthesis reaction of hydrogen with carbon monoxide by cooling the products to approximately 40-100 DEG F., preferably 50-60 DEG  F., to obtain oil and aqueous phases, the latter containing acids, esters, aldehydes, ketones and alcohols, fractionally distilling from the aqueous phase a light fraction of oxygenated hydrocarbons boiling below approximately 212 DEG  F. and containing mainly ethyl, propyl, butyl and amyl alcohols as azeotropes with water and leaving a bottoms fraction containing acids and residual undistilled water.  Preferably a portion of the bottoms fraction is contacted in countercurrent with the oil phase to remove neutral oxygenated hydrocarbons therefrom and may then be recycled to the distillation zone.  The bottoms fraction is also preferably passed to a second distillation zone in which a fraction containing higher boiling oxygenated hydrocarbons is recovered as an overhead which may be used for the above countercurrent treatment.  It is preferred that the pressure in the cooling zone is the same as that maintained during the synthesis and in the distillation zones is about 1 atmos.  The temperature at the top of the initial distillation zone is preferably in the range 208 DEG  or 210 DEG  to 212 DEG  F., and for the second distillation zone 212-220 DEG  F., desirably 213-216 DEG  F. Preferably the overhead from the second distillation zone is cooled to approximately 100 DEG  F. and the amount of aqueous phase to counter-currently treat the oil phase is 3-50 vols. of water per vol. of oil.  In general this treatment should be effected at 50-150 DEG  F.  In an illustration, oxides of carbon and hydrogen are reacted in the presence of an iron catalyst at about 550-650 DEG  F. and about 200-300 pounds per square inch, the products being condensed at approximately 40-100 DEG  F. before passing to a gas separating zone from which uncondensed gases may be removed and are preferably recycled.  The condensate is passed to a settling zone where the aqueous layer is withdrawn, passed to the initial distillation zone, an alcohol rich fraction boiling below approximately 212 DEG  F. is removed, cooled, condensed and allowed to separate from uncondensed constituents.  The bottoms fraction from the distillation is passed to a secondary distillation zone where there is removed overhead a phase rich in water, although containing some oxygenated compounds, which may be run off, but is preferably recycled to treat the oil phase in countercurrent.  The bottoms fraction from this distillation zone is recovered.  The oil phase is passed from the first separation zone through two countercurrent treatment zones in the second of which it meets the above recycled phase rich in water and in the first of which it meets the said recycled phase passed from the second countercurrent stage.  The oil phase is recovered from the second countercurrent stage and the aqueous phase from the first is recycled to the initial distillation zone.  In examples: (1) a sample of oil product is extracted successively 10 times with distilled water, a table giving the quantities of oxygenated compounds removed and remaining being provided, and in (2) a synthesis reaction is effected at 625 DEG  F. and 300 pounds per square inch about 750 vols. of synthesis gas per vol. of catalyst per hour being used with a recycle ratio of about 2 vols. of recycle gas per vol. of fresh feed, an iron catalyst promoted with 1 1/2 per cent of potassium carbonate is used, the products are cooled to about 60 DEG  F., the aqueous phase distilled to give a fraction boiling below about 212 DEG  F. containing alcohols having 2, 3, 4 or 5 carbon atoms per molecule and some low boiling aldehydes and ketones, the bottoms is passed to a second distillation zone maintained at a temperature just sufficient to remove water overhead, it being desirable that both distillation zones have efficiencies of about 20-40 plates and reflux ratios of about 5-10 vols. of reflux per vol. of fresh feed, and tables are provided showing the quantities and character of the products obtained in the two zones.ALSO:Oxygenated hydrocarbons are separated from vaporous products obtained by the hydrocarbon synthesis reaction of hydrogen with carbon monoxide by cooling the products to approx. 40-100 DEG  F., preferably 50-60 DEG  F., to obtain oil and aqueous phases, the latter containing acids, esters, aldehydes, ketones and alcohols, fractionally distilling from the aqueous phase a light fraction of oxygenated hydrocarbons boiling below approx. 212 DEG  F. and containing mainly ethyl, propyl, butyl and amyl alcohols as azeotropes with water and leaving a bottoms fraction containing acids and residual undistilled water.  Preferably a portion of the bottoms fraction is contracted in counter-current with the oil phase to remove neutral oxygenated hydrocarbons therefrom and then recycled to the distillation stage.  The bottoms fraction is also preferably passed to a second distillation zone in which a fraction containing higher boiling oxygenated hydrocarbons is recovered as an overhead which may be used for the above counter-current treatment and a residue is obtained containing the bulk of the higher boiling, e.g. 220-500 DEG  F., oxygenated hydrocarbons such as esters, aldehydes, ketones, acids and alcohols.  For further details (see Group IV (b)).