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.

Claims

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.sub.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.Math.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.

Description

[0132] The present invention is described in more detail below on the basis of exemplary embodiments with reference to the enclosed drawings. In this connection:

[0133] FIG. 1 shows a simplified diagrammatic representation of an exemplary separation process for the treatment and separation of a gaseous material mixture which was obtained by catalytic conversion of synthesis gas.

[0134] Subsequently, a description is given, with reference to the simplified reaction scheme according to FIG. 1, by way of example of a possible process for the separation of a product mixture obtained in the catalytic conversion of synthesis gas. The exemplary process described below for the separation describes the separation from the gas phase of the mixture of alcohols, alkenes and alkanes obtained by the conversion of the synthesis gas and its subsequent separation into a mixture of alcohols and a mixture of hydrocarbons. On using the different process variants and converting the product mixture obtained, the individual stages of this process for the separation of the product mixture can be varied and be adapted to the product mixture obtained after the conversion.

[0135] Removal of Inert Gas and Gas-Liquid Separation

[0136] After the catalytic conversion of a synthesis gas stream under the conditions of the process according to the invention, a product stream is present at a temperature of 280° C. and a pressure of 60 bar. The latter is initially reduced in a turbine (not represented in FIG. 1) to a pressure of 5 to 20 bar, preferably to about 10 bar, electrical energy being recovered which can be used for the electricity requirement of the process.

[0137] The subsequent gas-liquid separation is used in particular for the separation of the inert gases (nitrogen) and unconverted components of the synthesis gas (hydrogen, carbon monoxide and possibly carbon dioxide, and also the byproducts carbon dioxide and methane) and is carried out by introducing the crude product gas stream 10 into an absorption apparatus 11, in which the absorption of the product stream in a diesel oil (reference component dodecane) or alternatively in an alkane or a hydrocarbon mixture with a comparatively low viscosity of for example less than 10 mPas at ambient temperature and with preferably a comparatively high boiling point of in particular more than 200° C. is carried out. The water is in this connection not absorbed but for the most part condensed as second liquid phase. The separated abovementioned gaseous components can be led back via the line 12 to the catalytic conversion of the synthesis gas (not represented here) and be converted there once again.

[0138] The two liquid phases (organic phase and aqueous phase) obtained in this absorption operation, which can be carried out at a pressure of for example about 10-20 bar, can subsequently be separated in a decanter 13, little of the hydrocarbons but a portion of the alcohols going into the aqueous phase. The separation of the two liquid phases in the decanter 13 can for example likewise be carried out still at the abovementioned pressure of about 10-20 bar. The organic phase separated in this connection comprises the hydrocarbons, at least a portion of the alcohols, the absorption medium, possibly a portion of the water and also possibly amounts still remaining of inert and unconverted gases, in particular nitrogen and carbon monoxide, and is led to a desorption apparatus 15, via a line 14, in which the alcohols and hydrocarbons are desorbed from the absorption medium for example at low pressure, for example at a pressure of about 1 bar, and a bottom temperature of 216° C. A column, for example, can be used as desorption apparatus 15. With relatively low amounts of inert gases in the product stream of the catalytic conversion of synthesis gas, a condensation of the low boiling point components may alternatively also be suitable. The absorption medium (dodecane, diesel oil) can be led back to the absorption apparatus 11 via the line 16.

[0139] Separation of Alcohols/Hydrocarbons

[0140] The organic phase desorbed from the absorption medium in the desorption apparatus 15, which comprises the alcohols, hydrocarbons, small amounts of water and possibly amounts of unconverted and inert gases, is subsequently conveyed via a line 18 to a first distillation column 17. The separation of alcohols and hydrocarbons is carried out by distillation in this first column, preferably at a high pressure of for example 10 bar to 40 bar, for example at about 36 bar, and a bottom temperature of for example 221° C., so that the C3 constituents remain still condensable even in the presence of inert gas residues possibly present. This separation is preferably operated in such a way that the hydrocarbons are virtually completely removed from the alcohol fraction at the bottom, while relatively small contents of alcohol (in particular methanol) can be tolerated in the hydrocarbons. This process can optionally be assisted by a solubility-driven membrane. The alcohols obtained in this first distillation, which still comprise a proportion of water, can be withdrawn from the first distillation column 17 via the line 19 from the bottom and dried, as is more fully explained subsequently.

[0141] Preparation of the Hydrocarbons

[0142] The hydrocarbons obtained in the first distillation column 17 at the top can be conveyed, via a line 20, to a second distillation column 21, in which they are recovered at elevated pressure of preferably 5 bar to 20 bar, for example at a pressure of about 10 bar, and a bottom temperature of 102° C. at the top of the distillation column 21, and can be withdrawn, via the product line 22, for further purification and optionally separation into individual carbon fractions (not represented in FIG. 1). The alkanes possibly present in the product stream 22 of hydrocarbons can be separated from the alkenes, by preferably carrying out a hydration of the alkenes, so that these are converted to alcohols, which then can be separated comparatively simply from the alkanes, for example by distillation.

[0143] The remaining water and also the alcohols dissolved therein are obtained in the bottom of this second distillation column 21. This stream is separated and can be led back, via the line 23, for the recovery of the alcohols in a third distillation column 24. The condenser of the column can, for example, be a partial condenser. The outputs of the column are a gas phase of hydrocarbons and inerts, a liquid phase of hydrocarbons and also an aqueous phase which can be returned to the column as reflux.

[0144] The aqueous phase separated from the organic phase in the decanter 13 is conveyed, via the line 28, to the third distillation column 24, which aqueous phase can comprise amounts of the alcohols since these are at least partially soluble in water, in particular the lower alcohols, such as methanol and ethanol. The distillation in this third distillation column 24 can, for example, be carried out at a pressure of about 2 bar and at a temperature in the bottom of, for example, about 120° C. The alcohols present in this aqueous fraction are recovered at the top of the third column and conveyed, via the line 29, to the first distillation column 17 and combined there with the mixture of alcohols and hydrocarbons from the organic phase, so that these alcohols recovered from the aqueous phase can be separated in the first distillation column 17 with the rest of the alcohols and subsequently, for example, dried via the molecular sieve 25. The water separated in this third distillation column can, for example, be withdrawn from the plant via the line 30 as wastewater.

[0145] In this way, the useful materials, alkenes and alcohols, can be recovered each time as separate product groups by means of the separation scheme represented in exemplary and simplified fashion in FIG. 1 from the crude gas product mixture 10 through absorption in a high boiling point hydrocarbon or hydrocarbon mixture, subsequent decanting for the phase separation and subsequent repeated distillation.

[0146] Removal of Water from the Alcohol Fraction

[0147] The alcohol fraction from the first distillation column 17 can have a water content of for example about 10%. This water can, for example, be removed using a molecular sieve 25. In this process variant, the alcohols are conveyed, via the line 19, to the molecular sieve 25, by means of which water is removed from them, it being possible for the water to be withdrawn from the plant via the line 26. The alcohols dried in this way can be withdrawn via the product line 27 and optionally further separated, for example into individual carbon fractions (isomeric alcohols with each time the same number of carbon atoms) or into individual specific alcohols.

[0148] Suitable as alternative method for removing the water from the alcohol fraction is extractive distillation, for example with ethylene glycol, which however requires a further separation stage since the water is pulled from the ethylene glycol into the bottom while the alcohols methanol and ethanol proceed via the top virtually free from water. About half of the propanol and all of the butanol remain in the bottom and these C3-C4 alcohols must likewise be removed via the top from the ethylene glycol in a subsequent column.

[0149] Pervaporation is possible as third alternative. In this connection, water passes selectively through a membrane and is withdrawn as permeate in vapor form. The energy consumption is even lower than in a molecular sieve.

[0150] A further alternative method would be an azeotropic distillation, for example with butane or pentane as selective additive.

[0151] Examples for the Composition of the Product Mixture Obtained After the Catalytic Conversion of the Synthesis Gas

[0152] In the context of the present invention, it has been investigated how the variation in different parameters has an effect on the composition of the gaseous material mixture obtained after the catalytic conversion of the synthesis gas. The results are reproduced in the following examples.

EXAMPLE 1

[0153] The following example 1 gives an exemplary product composition which was obtained in the catalytic conversion of synthesis gas according to the process according to the invention. The catalyst used exhibited a high C2-C4 selectivity, alcohols, alkenes and alkanes being formed. A catalyst which comprises grains of nongraphitic carbon with cobalt nanoparticles dispersed therein was used. The CO selectivity with regard to the conversion to alcohols is about 28% and the CO selectivity with regard to the conversion to alkenes is about 32%. The precise CO selectivities of the catalytic conversion of the synthesis gas are apparent from the following table 1. The selectivities given in table 1 were normalized to the products detected in the catalytic tests (C1-C5 alcohols, C1-C5 alkenes and C1-C5 alkanes, CO.sub.2). The analysis of the CO conversion allows it to be concluded therefrom that, besides named products detected, long-chain C.sub.6+ alcohols, C.sub.6+ alkenes and C.sub.6+ alkanes, and also possibly aldehydes, are also formed.

TABLE-US-00001 TABLE 1 CO Selectivity CO.sub.2 9.8% Methane 17.9%  Ethane 4.6% Propane 4.3% Butane 3.0% Pentane 0.3% Ethene 6.0% 1-Propene 15.1%  1-Butene 7.2% 1-Pentene 4.2% Methanol 3.7% Ethanol 4.6% 1-Propanol 1.1% 1-Butanol 18.3%  Alkanes (C2-C5) 12.2%  Alkenes (C2-C5) 32.5%  Higher alcohols 24.0% 

[0154] A pulverulent catalyst was used in this example. The catalyst can alternatively also be pressed into tablets, for example.

[0155] Table 1 above shows that, in the catalytic conversion of the synthesis gas according to the invention, a comparatively high proportion of alcohols compared with the alkenes can be obtained if a suitable catalyst is used. The proportion of alkanes in the product mixture is lower in comparison thereto. The alkenes can likewise be converted to alcohols in the following hydration stage so that, inclusive of the following hydration stage, the synthesis gas can be converted overall into alcohols with a CO selectivity of virtually 60%, primary alcohols (methanol, ethanol, 1-propanol and 1-butanol) being obtained from the alcohol synthesis and ethanol and secondary alcohols (2-propanol, 2-butanol and possibly 2-pentanol) being obtained from the hydration stage and the methanol content being comparatively low. Such an alcohol mixture is suitable, for example, as fuel additive for blending with gasoline. The separation into the individual alcohols is alternatively possible.

[0156] For comparison, a CO.sub.0.126Mo.sub.0.255C catalyst was used, as described in the US document US 2014/0142206 A1 in Example 2. The H.sub.2 to CO ratio in the synthesis gas was 1:1. After the conversion of the synthesis gas, a composition according to the following table 1a was obtained.

TABLE-US-00002 TABLE 1a CO Selectivity CO.sub.2  3.80% Methane  1.27% C2-C6 hydrocarbons 1.0% Methanol 26.21% Ethanol 30.70% 1-Propanol 33.60% 1-Butanol  2.00% Higher alcohols 3.8%

[0157] The above table 1a shows that, on using this catalyst, predominantly alcohols are formed, the proportion of methanol being comparatively high while only a little 1-butanol is formed. C2-C6 hydrocarbons are only formed in small amounts.

[0158] For further comparison, a catalyst with high selectivity for olefins was used, as described in Example 2 of U.S. Pat. No. 4,510,267 A. After the conversion of the synthesis gas, a composition according to the following table 1b was obtained. The composition of the synthesis gas was in this case H.sub.2:CO=1:1. The selectivities (% by weight) given in U.S. Pat. No. 4,510,267 A and in table 1b were recalculated in CO selectivities for comparison with the results in Table 1 and for the simulation of the separation process. The selectivity for CO.sub.2 was determined from the difference from 100% and the sum of all products. For the simulation of the separation process, the C.sub.11+ alkanes and the C.sub.11+ alkenes were assumed to be undecane or undecene.

TABLE-US-00003 TABLE 1b % by weight CO Selectivity Methane 12.3%  11.96% Ethane 0.9% 0.93% Propane 1.4% 1.49% Butane 1.5% 1.61% Pentane 1.1% 1.19% Hexane traces 0.00% Heptane 0.8% 0.87% Octane 0.6% 0.66% Nonane 0.3% 0.33% Decane 0.4% 0.44% C.sub.11+ Alkanes 2.4% Undecane (assumption) — 2.63% Ethene 7.7% 8.56% Propene 15.2%  16.90% Butene 11.9%  13.23% Pentene 7.8% 8.67% Hexene 6.7% 7.45% Heptene 4.0% 4.45% Octene 2.4% 2.67% Nonene 1.7% 1.89% Decene 1.3% 1.45% C11+ Alkenes 6.5% Undecene (assumption) — 7.23% Methanol — 0.00% Ethanol 2.4% 1.62% CO.sub.2 — 3.79% Total 100.00%

[0159] The above table 1b shows that here predominately alkenes are formed but also a comparatively high proportion of methane. However, only a small amount of alcohols, namely ethanol, is formed.

[0160] For further comparison, the conversion with a Fischer-Tropsch reactor and a catalyst was simulated, as described in the literature by Syed Naqvi, SRI Consulting, Menlo Park, Calif. 94025, in PEP Review, 2007-2, December 2007, on page 5 in the right-hand column of table 1. The composition of the product mixture is reproduced in the following table 1c.

TABLE-US-00004 TABLE 1c F-T Product CO Selectivity C.sub.1 (Methane)  8% C.sub.2-C.sub.4 30% C.sub.5-C.sub.11 36% C.sub.12-C.sub.19 16% C.sub.19+  5% Oxygenates  5% Total 100%  C.sub.3-C.sub.4 Alkenes 87% C.sub.3-C.sub.4 Paraffins 13% Total 100%  C.sub.5-C.sub.12 (Alkenes) 70% C.sub.5-C.sub.12 (Alkanes) 13% C.sub.5-C.sub.12 (Aromatics)  5% C.sub.5-C.sub.12 (Oxygenates) 12% Total 100%  C.sub.13-C.sub.18 (Alkenes) 60% C.sub.13-C.sub.18 (Alkanes) 15% C.sub.13-C.sub.18(Aromatics) 15% .sub.13-C.sub.18 (Oxygenates) 10% Total 100% 

[0161] The above table 1c shows that here a multitude of compounds are produced, namely higher alkanes with up to 20 carbon atoms, higher alkenes, aromatic hydrocarbons, and alcohols with up to 19 carbon atoms. The proportion of methane was 8%. A total of 30% of compounds with C2-C4, 36% of compounds with C5-C11, 12% of compounds with C12-C19, 5% of compounds with more than 19 carbon atoms and 5% of oxygenates were formed. The selectivity of the formation of CO.sub.2 is not represented.

EXAMPLE 2

[0162] In this example, the distribution of the compounds of the product mixture which arose after the synthesis of higher alcohols in the three phases which are formed after the separation stage with the absorption medium (in this example dodecane) is clarified, a mixture being separated which arose after the conversion with a catalyst according to example 1, table 1. The catalyst comprised grains of nongraphitic carbon with cobalt nanoparticles dispersed therein. In the example according to table 2a, the assumed CO conversion was 50% while that in the example according to table 2b was 75%. The different CO conversions in the individual examples are achieved through the catalytic conversion of the synthesis gas in one or more reactors placed in series with addition of hydrogen at intervals for adjustment of the H.sub.2:CO ratio of H.sub.2:CO=1:1.

TABLE-US-00005 Example No. 2a: Variation CO conversion Catalyst: (see above) Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 3528

TABLE-US-00006 TABLE 2a CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase phase phase absorbed/mol mol/h 12 Liquid 28 14 Total dodecane H.sub.2 175 100%   0% 0%  0% 100% 5.0E−02 CO 2501 99%   1% 0%  1% 100% 7.1E−01 CO.sub.2 245 93%   7% 0%  7% 100% 6.9E−02 CH.sub.4 447 97%   3% 0%  3% 100% 1.3E−01 N.sub.2 4280 99%   1% 0%  1% 100% 1.2E+00 MeOH 93 1%  99% 82%  18% 100% 2.6E−02 EtOH 57 0% 100% 68%  32% 100% 1.6E−02 1-PrOH 9 0% 100% 43%  57% 100% 2.6E−03 1-BuOH 114 0% 100% 18%  82% 100% 3.2E−02 H.sub.2O 1737 1%  99% 98%   1% 100% 4.9E−01 Ethane 57 82%   18% 0% 18% 100% 1.6E−02 Propane 36 43%   57% 0% 57% 100% 1.0E−02 n-Butane 19 0% 100% 0% 100%  100% 5.3E−03 n-Pentane 1 0% 100% 0% 100%  100% 3.4E−04 Ethene 76 89%   11% 0% 11% 100% 2.1E−02 Propene 126 53%   47% 0% 46% 100% 3.6E−02 1-Butene 45 0% 100% 0% 100%  100% 1.3E−02 1-Pentene 21 0% 100% 0% 100%  100% 6.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

TABLE-US-00007 Example No. 2b: Variation CO conversion Catalyst: as in examples 2 and 2a Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 3528

TABLE-US-00008 TABLE 2b CO conversion: 75% Crude Gas Aqueous Org. mol gas 10 phase phase phase absorbed/mol mol/h 12 Liquid 28 14 Total dodecane H.sub.2 88 99%   1% 0%  1% 100% 1.3E−04 CO 1251 99%   1% 0%  1% 100% 3.8E−03 CO.sub.2 367 92%   8% 0%  8% 100% 8.7E−03 CH.sub.4 671 96%   4% 0%  4% 100% 7.3E−03 N.sub.2 4280 99%   1% 0%  1% 100% 7.9E−03 MeOH 139 0% 100% 86%  14% 100% 3.9E−02 EtOH 86 0% 100% 73%  27% 100% 2.4E−02 1-PrOH 14 0% 100% 50%  50% 100% 4.0E−03 1-BuOH 171 0% 100% 24%  76% 100% 4.9E−02 H.sub.2O 2606 1%  99% 99%   0% 100% 7.3E−01 Ethane 86 80%   20% 0% 20% 100% 5.0E−03 Propane 54 36%   64% 0% 64% 100% 9.7E−03 n-Butane 28 0% 100% 0% 100%  100% 8.0E−03 n-Pentane 2 0% 100% 0% 100%  100% 5.1E−04 Ethene 113 87%   13% 0% 13% 100% 4.1E−03 Propene 189 48%   52% 0% 52% 100% 2.8E−02 1-Butene 67 0% 100% 0% 100%  100% 1.9E−02 1-Pentene 32 0% 100% 0% 100%  100% 9.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

EXAMPLE 3

[0163] In the following example, the proportion of inert gas in the feed gas stream of the synthesis gas, which was catalytically converted to higher alcohols, i.e. the nitrogen content, varied with 10%, 20% and 30% (examples 3a, 3b and 3c). In this connection, the result was that the proportion of the lower alkenes and alkanes absorbed in the stage of the absorption of the product mixture in the high boiling point hydrocarbon of the organic liquid phase in each case decreases with increasing proportion of inert gas. This is valid for ethane, propane, ethene and propene, while the higher alkanes and alkenes from C4 in each case pass 100% into the organic liquid phase.

TABLE-US-00009 Example No. 3a: Variation proportion inert gas Catalyst: as in examples 2, 2a and 2b Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 45% — CO 5000 45% — N.sub.2 1110 10% — n-Dodecane — — 3528

TABLE-US-00010 TABLE 3a CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 99%   1% 0%  1% 100% 3.6E−04 CO 2501 98%   2% 0%  2% 100% 1.1E−02 CO.sub.2 245 88%   12% 0% 12% 100% 8.5E−03 CH.sub.4 447 94%   6% 0%  6% 100% 7.1E−03 N.sub.2 1110 99%   1% 0%  1% 100% 3.0E−03 MeOH 93 0% 100% 82%  18% 100% 2.6E−02 EtOH 57 0% 100% 66%  34% 100% 1.6E−02 1-PrOH 9 0% 100% 42%  58% 100% 2.6E−03 1-BuOH 114 0% 100% 18%  82% 100% 3.2E−02 H.sub.2O 1737 1%  99% 99%   1% 100% 4.9E−01 Ethane 57 70%   30% 0% 30% 100% 4.9E−03 Propane 36 8%  92% 0% 92% 100% 9.4E−03 n-Butane 19 0% 100% 0% 100%  100% 5.3E−03 n-Pentane 1 0% 100% 0% 100%  100% 3.4E−04 Ethene 76 81%   19% 0% 19% 100% 4.0E−03 Propene 126 19%   81% 0% 81% 100% 2.9E−02 1-Butene 45 0% 100% 0% 100%  100% 1.3E−02 1-Pentene 21 0% 100% 0% 100%  100% 6.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

TABLE-US-00011 Example No. 3b: Variation proportion inert gas Catalyst: as in example 3a Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 40% — CO 5000 40% — N.sub.2 2500 20% — n-Dodecane — — 3528

TABLE-US-00012 TABLE 3b CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 99%   1% 0%  1% 100% 2.7E−04 CO 2501 99%   1% 0%  1% 100% 8.2E−03 CO.sub.2 245 91%   9% 0%  9% 100% 6.3E−03 CH.sub.4 447 96%   4% 0%  4% 100% 5.3E−03 N.sub.2 2500 99%   1% 0%  1% 100% 5.3E−03 MeOH 93 0% 100% 82%  18% 100% 2.6E−02 EtOH 57 0% 100% 67%  33% 100% 1.6E−02 1-PrOH 9 0% 100% 43%  57% 100% 2.6E−03 1-BuOH 114 0% 100% 18%  82% 100% 3.2E−02 H.sub.2O 1737 1%  99% 99%   1% 100% 4.9E−01 Ethane 57 77%   23% 0% 23% 100% 3.8E−03 Propane 36 25%   75% 0% 75% 100% 7.7E−03 n-Butane 19 0% 100% 0% 100%  100% 5.3E−03 n-Pentane 1 0% 100% 0% 100%  100% 3.4E−04 Ethene 76 86%   14% 0% 14% 100% 3.0E−03 Propene 126 38%   62% 0% 62% 100% 2.2E−02 1-Butene 45 0% 100% 0% 100%  100% 1.3E−02 1-Pentene 21 0% 100% 0% 100%  100% 6.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

TABLE-US-00013 Example No. 3c: Variation proportion inert gas Catalyst: as in examples 3a and 3b Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 3528

TABLE-US-00014 TABLE 3c CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 100%   0% 0%  0% 100% 5.0E−02 CO 2501 99%   1% 0%  1% 100% 7.1E−01 CO.sub.2 245 93%   7% 0%  7% 100% 6.9E−02 CH.sub.4 447 97%   3% 0%  3% 100% 1.3E−01 N.sub.2 4280 99%   1% 0%  1% 100% 1.2E+00 MeOH 93 1%  99% 82%  18% 100% 2.6E−02 EtOH 57 0% 100% 68%  32% 100% 1.6E−02 1-PrOH 9 0% 100% 43%  57% 100% 2.6E−03 1-BuOH 114 0% 100% 18%  82% 100% 3.2E−02 H.sub.2O 1737 1%  99% 98%   1% 100% 4.9E−01 Ethane 57 82%   18% 0% 18% 100% 1.6E−02 Propane 36 43%   57% 0% 57% 100% 1.0E−02 n-Butane 19 0% 100% 0% 100%  100% 5.3E−03 n-Pentane 1 0% 100% 0% 100%  100% 3.4E−04 Ethene 76 89%   11% 0% 11% 100% 2.1E−02 Propene 126 53%   47% 0% 46% 100% 3.6E−02 1-Butene 45 0% 100% 0% 100%  100% 1.3E−02 1-Pentene 21 0% 100% 0% 100%  100% 6.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

EXAMPLE 4

[0164] In the following exemplary embodiment, the amount of substance of the absorption medium used (in this instance dodecane) was varied each time. A product gas mixture which was obtained in the catalytic conversion of a synthesis gas mixture with the composition given in example 1 according to table 1 was subjected to the separation stage. In this connection, in four different simulations, 25%, 50%, 100% or 150% of the absorption medium was used. The results are reproduced in the following tables of examples 4a to 4d.

TABLE-US-00015 Example No. 4a: Variation absorption medium amount Catalyst: as in example 3 Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 886 (25%)

TABLE-US-00016 TABLE 4a CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 100%   0% 0%  0% 100% 2.5E−04 CO 2501 100%   0% 0%  0% 100% 7.5E−03 CO.sub.2 245 98%  2% 0%  2% 100% 5.1E−03 CH.sub.4 447 99%  1% 0%  1% 100% 4.4E−03 N.sub.2 4280 100%   0% 0%  0% 100% 7.4E−03 MeOH 93 14% 86% 79%   7% 100% 8.9E−02 EtOH 57 11% 89% 74%  15% 100% 5.7E−02 1-PrOH 9  1% 99% 64%  36% 100% 1.0E−02 1-BuOH 114  0% 100%  40%  60% 100% 1.3E−01 H.sub.2O 1737  2% 98% 98%   0% 100% 1.9E+00 Ethane 57 96%  4% 0%  4% 100% 2.9E−03 Propane 36 88% 12% 0% 12% 100% 5.0E−03 n-Butane 19 63% 37% 0% 37% 100% 7.9E−03 n-Pentane 1  3% 97% 0% 97% 100% 1.3E−03 Ethene 76 97%  3% 0%  3% 100% 2.4E−03 Propene 126 90% 10% 0% 10% 100% 1.4E−02 1-Butene 45 68% 32% 0% 32% 100% 1.6E−02 1-Pentene 21  9% 91% 0% 91% 100% 2.2E−02 n-Dodecane 886  0% 100%  0% 100%  100% 1.0E+00

TABLE-US-00017 Example No. 4b: Variation absorption medium amount Catalyst: as in example 4a Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 1767 (50%)

TABLE-US-00018 TABLE 4b CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 100%   0% 0%  0% 100% 2.3E−04 CO 2501 100%   0% 0%  0% 100% 6.8E−03 CO.sub.2 245 97%  3% 0%  3% 100% 4.8E−03 CH.sub.4 447 98%  2% 0%  2% 100% 4.1E−03 N.sub.2 4280 100%   0% 0%  0% 100% 7.1E−03 MeOH 93  7% 93% 82%  11% 100% 4.9E−02 EtOH 57  1% 99% 76%  23% 100% 3.2E−02 1-PrOH 9  0% 100%  54%  46% 100% 5.3E−03 1-BuOH 114  0% 100%  28%  72% 100% 6.5E−02 H.sub.2O 1737  1% 99% 98%   0% 100% 9.7E−01 Ethane 57 91%  9% 0%  9% 100% 2.8E−03 Propane 36 74% 26% 0% 26% 100% 5.3E−03 n-Butane 19 11% 89% 0% 89% 100% 9.5E−03 n-Pentane 1  0% 100%  0% 100%  100% 6.8E−04 Ethene 76 95%  5% 0%  5% 100% 2.3E−03 Propene 126 79% 21% 0% 21% 100% 1.5E−02 1-Butene 45 22% 78% 0% 78% 100% 2.0E−02 1-Pentene 21  0% 100%  0% 100%  100% 1.2E−02 n-Dodecane 1767  0% 100%  0% 100%  100% 1.0E+00

TABLE-US-00019 Example No. 4c: Variation absorption medium amount Catalyst: as in examples 4a and 4b Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 3528 (100%)

TABLE-US-00020 TABLE 4c CO conversion: 50% Crude Gas Aqueous Org. mol gas 12 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 100%   0% 0%  0% 100% 5.0E−02 CO 2501 99%   1% 0%  1% 100% 7.1E−01 CO.sub.2 245 93%   7% 0%  7% 100% 6.9E−02 CH.sub.4 447 97%   3% 0%  3% 100% 1.3E−01 N.sub.2 4280 99%   1% 0%  1% 100% 1.2E+00 MeOH 93 1%  99% 82%  18% 100% 2.6E−02 EtOH 57 0% 100% 68%  32% 100% 1.6E−02 1-PrOH 9 0% 100% 43%  57% 100% 2.6E−03 1-BuOH 114 0% 100% 18%  82% 100% 3.2E−02 H.sub.2O 1737 1%  99% 98%   1% 100% 4.9E−01 Ethane 57 82%   18% 0% 18% 100% 1.6E−02 Propane 36 43%   57% 0% 57% 100% 1.0E−02 n-Butan 19 0% 100% 0% 100%  100% 5.3E−03 n-Pentane 1 0% 100% 0% 100%  100% 3.4E−04 Ethene 76 89%   11% 0% 11% 100% 2.1E−02 Propene 126 53%   47% 0% 46% 100% 3.6E−02 1-Butene 45 0% 100% 0% 100%  100% 1.3E−02 1-Pentene 21 0% 100% 0% 100%  100% 6.0E−03 n-Dodecane 3528 0% 100% 0% 100%  100% 1.0E+00

TABLE-US-00021 Example No. 4d: Variation absorption medium amount Catalyst: as in examples 4a to 4c Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 5289 (150%)

TABLE-US-00022 TABLE 4d CO conversion: 50% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 175 99%   1% 0%  1% 100% 2.0E−04 CO 2501 99%   1% 0%  1% 100% 6.0E−03 CO.sub.2 245 90%   10% 0% 10% 100% 4.7E−03 CH.sub.4 447 95%   5% 0%  5% 100% 3.9E−03 N.sub.2 4280 99%   1% 0%  1% 100% 7.1E−03 MeOH 93 0% 100% 77%  23% 100% 1.7E−02 EtOH 57 0% 100% 60%  40% 100% 1.1E−02 1-PrOH 9 0% 100% 35%  65% 100% 1.8E−03 1-BuOH 114 0% 100% 13%  87% 100% 2.2E−02 H.sub.2O 1737 1%  99% 98%   1% 100% 3.3E−01 Ethane 57 73%   27% 0% 27% 100% 2.9E−03 Propane 36 15%   85% 0% 85% 100% 5.8E−03 n-Butane 19 0% 100% 0% 100%  100% 3.5E−03 n-Pentane 1 0% 100% 0% 100%  100% 2.3E−04 Ethene 76 84%   16% 0% 16% 100% 2.3E−03 Propene 126 28%   72% 0% 72% 100% 1.7E−02 1-Butene 45 0% 100% 0% 100%  100% 8.5E−03 1-Pentene 21 0% 100% 0% 100%  100% 4.0E−03 n-Dodecane 5289 0% 100% 0% 100%  100% 1.0E+00

[0165] The amount of the absorption medium used (in the examples, dodecane was used) was varied in the above examples 4a to 4d with 886 kmol/h, 1767 kmol/h, 3528 kmol/h or 5289 kmol/h, it being possible to show that the amount of the alkenes and alkenes absorbed in the absorption medium increases approximately linearly with increasing molar flow, as expected the higher alkenes and alkanes (for example propene, propane) being more strongly absorbed than the lower alkenes and alkanes (ethene, ethane).

[0166] The alcohols methanol, ethanol, propanol and butanol, in the absorption operation, pass partly into the aqueous phase and partly into the dodecane phase, methanol and ethanol, as expected, passing predominantly into the aqueous phase while butanol, even at a low molar flow, already passes predominantly into the organic phase. The gases H.sub.2, CO, CO.sub.2, CH.sub.4 and N.sub.2 remain in the gas phase in this separation stage. At a low molar flow of the absorption medium, though, the lower alkenes and alkanes and sometimes also amounts of the higher alkenes (propene, 1-butene) and alkanes (propane, butane) pass into the gas phase. This, however, changes with increasing molar flow of the absorption medium. Thus, already at a molar flow of 3528 kmol/h, about half of the propene and 100% of the 1-butene passes into the organic liquid phase. At a still higher molar flow of 5289 kmol/h, the proportion of the propene absorbed in the organic phase increases even further. At a higher molar flow of the absorption medium, though, higher amounts of methanol and ethanol and also small amounts of CO.sub.2 and CH.sub.4 can also pass into the organic phase.

EXAMPLE 5

[0167] In the following exemplary embodiment, the catalyst was varied. A product gas mixture which was obtained in the catalytic conversion of a synthesis gas mixture with the composition given in example 1 according to table 1b was subjected to the separation stage. For the simulation, the selectivity for CO.sub.2 was determined from the difference from 100% by weight and the sum of all products. For the simulation of the separation process, the C.sub.11+ alkanes and the C.sub.11+ alkenes were assumed to be undecane or undecene.

TABLE-US-00023 Example No. 5: Variation catalyst Catalyst: Ru.sub.3(CO).sub.12/CeO.sub.2 (US 4 510 267 A) Composition synthesis gas Absorption medium Molar flow Mole fraction Molar flow [kmol/h] [%] [kmol/h] H.sub.2 5000 35% — CO 5000 35% — N.sub.2 4280 30% — n-Dodecane — — 3528

TABLE-US-00024 TABLE 5 CO conversion: 75% Crude Gas Aqueous Org. mol gas 10 phase Liquid phase phase absorbed/mol mol/h 12 phase 28 14 Total dodecane H.sub.2 <1 100%   0% 0%  0% 100% 2.3E−02 CO 1284 99%   1% 0%  1% 100% 7.9E+02 CO.sub.2 141 92%   8% 0%  8% 100% 8.7E+01 CH.sub.4 444 97%   3% 0%  3% 100% 2.7E+02 N.sub.2 4280 99%   1% 0%  1% 100% 2.6E+03 MeOH 0 0%  0% 0%  0%  0% 0.0E+00 EtOH 30 0% 100% 75%   25% 100% 1.9E+01 H.sub.2O 3404 0% 100% 99%   0% 100% 2.1E+03 Ethane 17 80%   20% 0%  19% 100% 1.1E+01 Propane 18 34%   66% 0%  66% 100% 1.1E+01 n- Butane 15 0% 100% 0% 100% 100% 9.2E+00 n-Pentane 9 0% 100% 0% 100% 100% 5.4E+00 n-Hexane 0 0%  0% 0%  0%  0% 0.0E+00 n-Heptane 5 0% 100% 0% 100% 100% 2.8E+00 n-Octane 3 0% 100% 0% 100% 100% 1.9E+00 n-Nonane 1 0% 100% 0% 100% 100% 8.3E−01 n-Decane 2 0% 100% 0% 100% 100% 1.0E+00 n-Undecane 9 0% 100% 0% 100% 100% 5.5E+00 Ethene 159 88%   12% 0%  12% 100% 9.8E+01 Propene 209 46%   54% 0%  54% 100% 1.3E+02 1-Butene 123 0% 100% 0% 100% 100% 7.6E+01 1-Pentene 64 0% 100% 0% 100% 100% 4.0E+01 1-Hexene 46 0% 100% 0% 100% 100% 2.8E+01 1-Heptene 24 0% 100% 0% 100% 100% 1.5E+01 1-Octene 12 0% 100% 0% 100% 100% 7.6E+00 1-Nonene 8 0% 100% 0% 100% 100% 4.8E+00 1-Decene 5 0% 100% 0% 100% 100% 3.3E+00 1-Undecene 24 0% 100% 0% 100% 100% 1.5E+01 n-Dodecane 3528 0% 100% 0% 100% 100% 2.2E+03

[0168] The results of this exemplary embodiment show that even an olefin-rich product gas mixture, which comprises a low proportion of alcohols, can be subjected to the separation stage. With the exception of the short-chain alkanes and alkenes (ethane, ethene, propane, propene), the alkanes and alkenes are virtually completely absorbed in the liquid phase and, after the phase separation, are virtually completely present in the organic liquid phase.

LIST OF REFERENCE NUMERALS

[0169] 10 feed inlet for the crude product gas stream

[0170] 11 absorption apparatus

[0171] 12 line for the discharge of the separated gaseous constituents

[0172] 13 decanter

[0173] 14 line for organic phase to the desorption apparatus

[0174] 15 desorption apparatus

[0175] 16 line for recycling the absorption medium

[0176] 17 first distillation column

[0177] 18 line for the feeding of the organic phase to the distillation column

[0178] 19 line to the drying for alcohols separated in the distillation

[0179] 20 line for hydrocarbons to the second distillation

[0180] 21 second distillation column

[0181] 22 line for the discharge of the hydrocarbons

[0182] 23 return line for the recycling of the alcohols

[0183] 24 third distillation column

[0184] 25 molecular sieve

[0185] 26 line for discharged water

[0186] 27 product line for discharged alcohols

[0187] 28 line for aqueous phase

[0188] 29 line for alcohols

[0189] 30 line for wastewater