Method for processing a gaseous composition

Abstract

A process can treat a gaseous material mixture obtained by catalytic conversion of synthesis gas that contains at least alkenes, possibly alcohols and possibly alkanes, and also possibly nitrogen as inert gas and unconverted components of the synthesis gas, comprising hydrogen, carbon monoxide and/or carbon dioxide. After catalytic conversion of synthesis gas, separation of the product mixture obtained in this reaction into a gas phase and a liquid phase is performed by at least partial absorption of the alkenes, possibly of the alcohols and possibly of the alkanes, in a high boiling point hydrocarbon or hydrocarbon mixture as an absorption medium, separation as the gas phase of the gases not absorbed into the absorption medium, separating an aqueous phase from the organic phase of the absorption medium, preferably by decanting, and desorption of the alkenes, possibly of the alcohols and possibly of the alkanes, from the absorption medium.

1 .- 21 . (canceled) 
     
     
         22 . A process for treating a gaseous material mixture that has been obtained by catalytic conversion of synthesis gas recovered from smelter gases, CO- or CO 2 -rich gases, hydrogen, or biomass, wherein the gaseous material mixture contains at least alkenes and alcohols, the process comprising:
 after the catalytic conversion of the synthesis gas, separating a product mixture obtained in the catalytic conversion into a gas phase and a liquid phase by at least partial absorption of the alkenes in a high boiling point hydrocarbon or hydrocarbon mixture as an absorption medium;   separating as the gas phase gases not absorbed into the absorption medium; and   separating an aqueous phase from an organic phase of the absorption medium;   desorption of the alkenes from the absorption medium,   wherein the high boiling point hydrocarbon or the hydrocarbon mixture used as the absorption medium comprises a diesel oil or an alkane with a viscosity of less than 10 mPa·s at an ambient temperature and a boiling point of more than 200° C.   
     
     
         23 . The process of  claim 22  comprising separating a mixture obtained after desorption comprising alkenes through a first distillation into a fraction comprising predominantly the hydrocarbons and a fraction comprising predominantly the alcohols. 
     
     
         24 . The process of  claim 23  comprising performing the first distillation at an elevated pressure in a pressure range from 10 bar to 40 bar. 
     
     
         25 . The process of  claim 23  comprising separating the hydrocarbons from the first distillation in a second distillation that is an extractive distillation with water, from residues of alcohol and water present in the hydrocarbons. 
     
     
         26 . The process of  claim 22  comprising separating from water alcohols present in the aqueous phase, after the separation of the aqueous phase from the organic phase, in a third distillation by azeotropic distillation. 
     
     
         27 . The process of  claim 26  comprising separating a mixture obtained after desorption comprising alkenes through a first distillation into a fraction comprising predominantly the hydrocarbons and a fraction comprising predominantly the alcohols, wherein the alcohols separated from the water in the third distillation are conveyed to the mixture obtained after the desorption and, with this mixture, separated from the hydrocarbons through the first distillation. 
     
     
         28 . The process of  claim 23  comprising removing water from the fraction comprising predominantly the alcohols obtained in the first distillation by way of a molecular sieve. 
     
     
         29 . The process of  claim 23  wherein an alcohol mixture obtained after the first distillation is subsequently separated through one or more distillation stages into alcohol fractions with, each time, a different number of carbon atoms, including a C1 fraction, a C2 fraction, a C3 fraction, and a C4 fraction. 
     
     
         30 . The process of  claim 25  wherein the alkenes present in the hydrocarbon mixture obtained after the desorption, the alkenes present in the hydrocarbon mixture obtained after the first distillation, or the alkenes present in the hydrocarbon mixture obtained after the second distillation are converted by hydration to give alcohols. 
     
     
         31 . The process of  claim 25  wherein the hydrocarbon mixture obtained after the second distillation is separated into fractions with, each time, the same number of carbon atoms, including a C3 fraction, a C4 fraction, and a C5 fraction. 
     
     
         32 . The process of  claim 23  wherein from the fraction comprising predominantly the alcohols, lower alcohols methanol and ethanol and small amounts of water are separated in a column and a remaining alcohol mixture is treated with a higher hydrocarbon and is separated in a decanter into an organic phase and an aqueous phase. 
     
     
         33 . The process of  claim 32  wherein the alcohols are stripped out from the organic phase in an additional column and residual water present in the alcohols is subsequently removed using a molecular sieve. 
     
     
         34 . The process of  claim 23  wherein from the fraction comprising predominantly the alcohols, lower alcohols methanol and ethanol are separated from higher alcohols in an extractive distillation with ethylene glycol, wherein the higher alcohols are subsequently separated from the ethylene glycol in an additional distillation column. 
     
     
         35 . The process of  claim 23  wherein from the fraction comprising predominantly the alcohols, water is selectively removed by pervaporation through a membrane and is withdrawn as permeate in vapor form. 
     
     
         36 . The process of  claim 23  wherein from the fraction comprising predominantly the alcohols, water is removed by azeotropic distillation with a higher hydrocarbon. 
     
     
         37 . The process of  claim 22  wherein from the gaseous material mixture obtained after the catalytic conversion of synthesis gas, at least C4 alkenes and C5 alkenes are recovered. 
     
     
         38 . The process of  claim 37  wherein the desorption of the alkenes and the alcohols from the absorption medium is performed in a distillation column. 
     
     
         39 . The process of  claim 38  wherein after the desorption, the absorption medium is led back into a separation stage of the absorption. 
     
     
         40 . The process of  claim 39  wherein the gas phase separated from the gases not absorbed in the absorption medium comprises at least one of nitrogen, hydrogen, carbon monoxide, or carbon dioxide. 
     
     
         41 . The process of  claim 22  wherein the gaseous material mixture comprises nitrogen from blast furnace gas that is at least partly removed from a stream using a gas permeation membrane.