DE102007030440A1 - Procedure for the production of methanol from synthesis gas, comprises catalytically transferring the synthesis gas containing carbon dioxide and hydrogen to methanol and then separating the methanol - Google Patents

Abstract

The procedure for the production of methanol from synthesis gas, comprises catalytically transferring the synthesis gas containing carbon dioxide and hydrogen to methanol and then separating the methanol. The methanol is led through n cation exchanger at 30-50 [deg] C to remove trimethylamine from the methanol. The cation exchanger is strong acid. The pressure drop is held over the ion exchanger at = 1 bar. An independent claim is included for a plant for the production of methanol from synthesis gas.

Description

The The present invention relates to a method and a plant for Production of methanol from a synthesis gas, wherein the carbon oxides and Hydrogen-containing synthesis gas catalytically converted to methanol and then the methanol is separated. In particular, the present Invention directed to the purification of the thus obtained methanol.

Methanol is an important, versatile raw material for the chemical industry, mainly derived from natural gas, but more recently from coal. Such as in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition Vol. A12, page 171 ff., the natural gas is first converted by catalytic reforming into a synthesis gas containing carbon oxides and hydrogen. This conversion traditionally takes place in steam reformers; since the 1970s, however, autothermal catalytic reformers, which are connected downstream of the steam reformer, are used to reduce pollutant emissions and save energy. Such methods are also referred to as "combined reforming".

Following the preparation of the synthesis gas, the methanol synthesis, as described for example in the EP 0 790 226 B1 is described. The methanol thus obtained is then separated from the unreacted synthesis gas, separated in a distillation column of other products and fed to the particular intended use.

at The reforming of natural gas is also formed ammonia, which at the methanol synthesis is converted to trimethylamine (TMA). The TMA even if the product contains> 50 ppb in the product cause fishy odor. The customer therefore calls for methanol usually a product purity that has that fishy smell excludes, for example, a limit of 30 ppb TMA is specified. The product methanol is after distillation in Pumped intermediate tanks and there to meet the quality requirements checked. If the limits are exceeded, the methanol is distilled again. This repeated distillation but increases the specific energy consumption per ton of produced Methanol and therefore the production costs.

TMA is a low boiler, which is usually easy in the Are distilled off distillation column in the methanol separation can. However, especially in the case of combined reforming, it may be in the Synthesis gas to strong ammonia formation come to a TMA content in the methanol product of a few hundred ppb can lead. This proportion can be in a single distillation stage do not remove sufficiently. Will in the review the product quality of the methanol too high TMA content determined, therefore, the methanol must be distilled again, to lower the TMA content below the required limit.

task The invention is the product quality in the production of methanol and in particular trimethylamine largely from to remove the methanol product.

These The object is achieved with the invention essentially by that the methanol passed through an ion exchanger becomes. It has been found that the trimethylamine in the Ion exchanger is absorbed very well, so that methanol with a TMA fraction of less than 10 ppb can be generated. Without additional Energy consumption can be TMA as one of the main ways Problem components inexpensive and reliable from the methanol be removed.

The Purification of the methanol from oversized TMA levels Of course, the ion exchanger can also be used independently from the preparation of the methanol by reforming and subsequent Synthesis done.

As an ion exchanger according to a preferred embodiment of the invention, a cation exchanger is used, which is particularly strongly acidic. A strongly acidic cation exchanger is understood as meaning an ion exchanger which dissociates very strongly in water, ie it releases H ⁺ ions. With such cation exchangers, the cations can be exchanged from salts of strong acids.

Around in the passage of the methanol through the ion exchanger an oversized plastic deformation of the ion exchange resin is to avoid the pressure drop over the ion exchanger preferably ≤ 1 kept bar.

Around to avoid damage to the resin, the methanol according to the invention with the ion exchanger a temperature <140 ° C, preferably 20-100 ° C and especially 30-50 ° C. guided.

The invention also extends to a plant for the production of methanol, which is particularly suitable for carrying out the process described above and at least one reactor for reacting a carbon oxides and hydrogen-containing synthesis gas to methanol, a separator for separating the recovered methanol and an ion exchanger, through which the methanol is passed.

Of the Ion exchanger is preferably a cation exchanger of a strong acidic polymer resin. In particular, the use of a sulfo nierten copolymer based on cross-linked divinylbenzene and styrene proved to be useful.

The Invention will be described below with reference to an embodiment and the drawing explained in more detail. Make up all described and / or illustrated features for itself or in any combination the subject of the invention, independently from their summary in the claims or their Dependency.

It demonstrate:

1 a plant for the production of methanol according to the invention;

2 the heat exchanger used for the purification of methanol.

At the in 1 schematically shown plant for the production of methanol, the natural gas used as raw material is first a desulfurization plant 1 fed and then passes through a steam pre-reformer 2 and an autothermal reformer 3 (combined reforming) before the methanol synthesis according to one example in the EP 0 790 226 B1 is fed described method. From the product of methanol synthesis 4 is in a separator 5 distilled methanol separated. This methanol is then passed through an ion exchanger 6 passed, in which the TMA content of the methanol is reduced below a predetermined limit, for example, 30 ppb. The recovered pure methanol is then fed to the particular intended use.

As an ion exchanger, as in 2 is shown in more detail, a strong acidic cation exchanger, in particular a sulfonated polymer resin based on cross-linked styrene / divinylbenzene copolymers is preferably used. The ion exchange resin is placed in a C-steel container 7 filled and flows through the methanol. As an example of a suitable for carrying out the process ion exchange resin can be made to the product marketed by Rohm and Haas polymer resin Amberlyst ^® 40WET. Such polymer resins are conventionally used in water chemistry, for example for the production of demineralized water, or as a catalyst.

The ion exchanger 6 is over a line 8th from the separator 5 withdrawn methanol supplied which the ion exchanger 6 with a temperature of 30 to 50 ° C and a pressure drop of about 1 bar passes. Here, the ion exchanger takes up the TMA until the resin is saturated. This can be seen from the fact that the TMA content in the product begins to increase. Usually, a batch of resin is designed for a service life of three years. Thereafter, the resin must be replaced.

aufweisen.When designing the ion exchanger, it should be taken into account that too small an amount of ion exchange resin does not sufficiently reduce the TMA content. On the other hand, an excessive amount of resin causes the pressure loss across the ion exchanger 6 becomes too large, which can lead to a plastic deformation of the resin in the container. Conveniently, the ion exchanger should be about

exhibit.

example

The ion exchanger 6 is over the line 8th 108,300 kg / h of methanol supplied to a temperature of 40 ° C at a pressure of 4 bar. The TMA content is, for example, 60 ppb, ie significantly above the predetermined limit of, for example, 30 ppb. The methanol flows through the ion exchanger 6 , which has a volume of 12 m ³ , and leaves it via the line 9 with substantially unchanged temperature, a pressure of about 3 bar and a TMA content of <10 ppb.

1

desulphurisation

2

prereformer

3

autothermal reformer

4

methanol synthesis

5

separator

6

ion exchanger

7

container

8th

management

9

management

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0790226 B1 [0003, 0018]

Cited non-patent literature

• - Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition Vol. A12, page 171 [0002]

Claims (10)

A process for the production of methanol from a synthesis gas, wherein the carbon oxides and hydrogen-containing synthesis gas is catalytically converted to methanol and then the methanol is separated, characterized in that the methanol is passed through an ion exchanger to remove trimethylamine from the methanol. Method according to claim 1, characterized in that that the methanol passed through a cation exchanger becomes. Method according to one of the preceding claims, characterized in that the ion exchanger is strongly acidic. Method according to one of the preceding claims, characterized in that the pressure loss over the Ion exchanger ≤ 1 bar is maintained. Method according to one of the preceding claims, characterized in that the methanol having a temperature <140 ° C, preferably 30 to 50 ° C is passed through the ion exchanger. Plant for the production of methanol, in particular for carrying out a process according to one of the preceding claims, with at least one reactor ( 4 ) for converting a synthesis gas containing carbon oxides and hydrogen into methanol and with a separation device ( 5 ) for the separation of the recovered methanol, characterized by an ion exchanger ( 6 ), through which the methanol is passed. Plant according to claim 6, characterized in that the ion exchanger ( 6 ) is a cation exchanger. Plant according to claim 6 or 7, characterized in that the ion exchanger ( 6 ) is a strong acidic polymer resin. Plant according to one of claims 6 to 8, characterized in that the ion exchanger ( 6 ) is a sulfonated copolymer. Use of a particularly strongly acidic cation exchanger for the removal of trimethylamine from methanol.