DE1792265B2 - PROCESS FOR PRODUCING A SYNTHESIS GAS FOR OXOSYNTHESIS - Google Patents

Description

The invention relates to a process for the production of a synthesis gas rich in carbon monoxide for oxo synthesis with a molar ratio H2: CO of 0.8: 1 to 1.2: 1 by reacting gaseous or liquid hydrocarbons with C numbers from 1 to 20 and an upper boiling limit of about 300 ⁰ C with Kohlenoioxid and steam over nickel catalysts at temperatures of about 750 ⁰ C ind elevated pressure.

Synthesis gases consisting of carbon monoxide and hydrogen are now mostly catalytic Splitting of liquid or gaseous hydrocarbons with water vapor is generated. The hydrogen content Such a gas can be produced by converting the carbon monoxide with water vapor to carbon dioxide and hydrogen are increased, if necessary so far that after washing out the carbon dioxide an almost pure one Hydrogen remains. Increasing the carbon monoxide content in such a gas is much more difficult. The leaching of carbon monoxide by means of ammoniacal copper salt solution from a partial flow of the synthesis gas and return to the other substream is in the case of large amounts of carbon monoxide economically out of the question. The catalytic hydrogenation of carbon monoxide to methane consumes 3 moles of hydrogen per mole of carbon monoxide, but undesired inert gas is formed.

Synthesis gases rich in carbon monoxide are to be understood as those in which the molar ratio H2: CO2 is approximately 0β : 1 to 1.2: 1. S tion of 1 mole of CO and mole of hydrogen on the opening double bond is converted into aldehydes; the aldehydes can be oxidized to carboxylic acids or reduced to alcohols. This course of the reaction results in an H2: CO ratio of 1: 1 for the composition of the synthesis gas. For the practical implementation of the synthesis, H2: CO ratios of 0.8: 1 to 1.2: 1 are suitable

Synthesis gases rich in carbon monoxide can break down high-boiling hydrocarbons in particular through oxidizing cleavage can be generated with water vapor and oxygen. A ratio of H2: CO of about 1: 1 can be generated. However, these methods require and have pure oxygen Disadvantage that worthless waste products such as soot are formed, their separation from the raw Fission gas causes additional costs. The production of synthesis gases by partial oxidation of Hydrocarbons is known from DT-PS 9 02 251, for example

The invention is based on the object of carrying out a method of the type mentioned at the outset in such a way that that the synthesis gas is kept free of troublesome soot. According to the invention, this is thereby achieved achieved that the reaction takes place on indirectly heated catalyst material in a tube furnace, the Carbon dioxide from the cracked gas generated therein is washed out and converted into the mixture to be converted in the tube furnace is recycled and that from at least part of the carbon dioxide-free cracked gas by cryogenic gas decomposition a carbon monoxide fraction is obtained, which with part of the carbon dioxide-free Fission gas or with part of the hydrogen fraction from the low-temperature gas separation to synthesis gas is combined for the oxo synthesis.

The reaction takes place in particular at pressures from 5 to 100 ata, preferably from 10 to 50 ata Temperatures between 850 and 1000 ° C and on catalysts, the 10 to 40, preferably 15 to 35 % By weight nickel on a carrier made of aluminum oxide or aluminum silicate.

The cracked gas generated in the tube furnace contains hydrogen and carbon monoxide in a ratio of about 2: 1 and only small amounts of methane. The carbon dioxide is washed out of the pipe cracked gas and fed back in front of the tube furnace, so that it can be circulated through this and the QV washout is held. In the low-temperature gas separation process, a small amount of methane is separated off a CO fraction and the remainder an H2 fraction obtained. Remains after the synthesis gas is assembled Hydrogen left over from the low-temperature gas decomposition, then it is available for hydrogenation in the oxo synthesis recovered aldehydes and optionally for desulfurization of the used as starting material Hydrocarbons available.

Preferably, only a partial flow of the carbon dioxide-free cracked gas is used in the generation of the synthesis gas led through the low-temperature gas separation and the CO fraction obtained in the process to the other

⁶ S partial flow admixed, while the hydrogen is available for hydrogenation purposes

In the process according to the invention, gaseous and liquid carbon

Hydrogen are split. While processing liquid hydrocarbons, it can be advantageous to lead the entire carbon dioxide-free cracked gas through the low-temperature gas decomposition in order to produce the cracked gas contained small amounts higher than boiling methane To be able to separate impurities in the gas separation process.

Further refinements of the method emerge from the subclaims.

example 1

A sulfur-free light gasoline in the boiling range 50 to 180 ° is after the addition of 4.0 kg of water vapor and 1.42 Nm ³ CO2 per kg of gasoline after evaporation and heating in a tube furnace at 800 to 870 ° C on a catalyst containing 20 wt .-% nickel contains on a support made of aluminum silicate, cleaved.

^{534 Nm 3 of} cracked gas of the following composition are produced per kg of gasoline

Heating gas used and 1.275Nm * H ₂ are available for the hydrogenation.

Example 2 A desulphurized natural gas of the composition

CH ₄ 85 ^ vol-%

C ₂ H ₆ £ 12 Vol-%

N ₂ 0.9% by volume

CjH ₈ 0.7% by volume

is cleaved in tube furnace at 830 to 88O ⁰ C over a nickel catalyst with 25 wt .-% nickel on a support of alumina with water vapor and carbon dioxide is. 2.0 kg of water vapor and 0395 Nm ^{3 of} carbon dioxide are used per Nm ^{3 of natural gas}

One Nm ^{3 of} natural gas produces 5.052 Nm ^{3 of} cracked gas with the following composition:

CO ₂ 24.08 vol%

CO 23.54% by volume

H ₂ 50.02% by volume

CH ₄ 236% by volume

1.43 NmVkg 1.40 NmVlCg 237 NmVkg 0.14 NmVkg

From this gas, the carbon dioxide, 1.42 Nm ³ , washed out to a few ppm from the loaded absorption solution is recovered by regeneration and returned to the feed mixture upstream of the tube furnace

The clean gas remaining after the CO ₂ has been washed out, 4.52 Nm ^{3, consists of}

CO 30.75% _{by volume -H 2} 65.50% by volume -CH ₄ 3.75% by volume -

139 NmVkg 2.96 NmVkg 0.17 NmVkg

It is divided into cryogenic gas separation in

1.46Nm ³ CO (95%) 2.95Nm ³ H ₂ (98%) 0.11Nm ³ CH ₄ (100%)

3.135 Nm ^{3 of} oxo synthesis gas with an H ₂ : Co ratio of 1.2: 1 are mixed from the Co fraction and part of the H _{2 fraction.} 0.11 Nm ³ methane are used as CO ₂ CO

H ₂

CH ₄

N ₂

H ₂ O (steam)

20.54% by volume

17.64% by volume

59.67% by volume

1.57% by volume

0.18% by volume

0.58% by volume

After washing out 0.895 Nm ^{3 of} carbon dioxide, which is returned to your Spak reactor, 4.157 Nm ^{3 of} pure gas remain with the following composition:

J5

CO ₂ below 150 ppm CO 25.42% full volume H ₂ 72.45% by volume CH ₄ 1.91% by volume N ₂ 0.22 vol.%

^{2.452 Nm 3 of} this pure gas are passed through the low-temperature gas separation. From this, natural gas used is obtained ^{for each Nm 3}

0.655 Nm ³ CO fraction

1.780 Nm ³ H ₂ fraction with 98% by volume of H ₂ 0.017Nm ³ inert gas _{fraction (N 2} )

The 0.655 Nm ³ Co fraction are combined with the portion of the pure gas that is not passed through the low temperature gas supply, 1705 Nm ³ , to form 235 Nm ^{3 of} oxo synthesis gas with an H ₂ .100 ratio of 1.2: 1.

Claims (4)

Patent claims: 1. Process for the preparation of a synthesis gas rich in carbon monoxide for the oxo synthesis with a molar ratio H ₂ : CO of 0.8: 1 to 1.2: 1 by reacting gaseous or liquid hydrocarbons with carbon numbers from 1 to 20 and an upper boiling limit of about 300 ⁰ C with carbon dioxide and water vapor on nickel catalysts at temperatures of over 750 ⁰ C and increased pressure, characterized in that the conversion takes place on indirectly heated catalyst material in a tube furnace, the carbon dioxide of the cracked gas generated therein is washed out and in the mixture to be reacted in the tube furnace is recycled and that a carbon monoxide fraction is obtained from at least part of the carbon dioxide-free cracked gas by low-temperature gas decomposition, which is combined with part of the carbon dioxide-free cracked gas or with part of the hydrogen fraction from the low-temperature gas decomposition to form synthesis gas for the oxo synthesis. 2. The method according to claim 1, characterized in that the reaction takes place in the tube furnace Pressures from 5 to 100 ata, preferably from 10 to 50 ata, is carried out. 3. The method according to claim 1 and 2, characterized in that the reaction takes place in the tube furnace at temperatures between 850 and 1000 ⁰ C. 4. The method according to any one of claims 1 to 3, characterized in that the reaction in Tube furnace takes place on catalysts, the 10 to 40, preferably 15 to 35 wt .-% nickel on a Contains aluminum oxide or aluminum suikai supports.