WO2003089547A1

WO2003089547A1 - Method for the desulphurization of products involved in crude oil fractionation

Info

Publication number: WO2003089547A1
Application number: PCT/EP2003/003486
Authority: WO
Inventors: Oliver PFÜLLER; Frank Ph. Walstra
Original assignee: Clariant Gmbh
Priority date: 2002-04-19
Filing date: 2003-04-03
Publication date: 2003-10-30
Also published as: EP1499697A1; DE10217469C1

Abstract

The invention relates to a method for the desulphurization of gasoline, diesel, gas oil and other crude oil fractions, using compounds of formula (1) as the extracting agent, wherein R1 represents H, C1 to C10 alkyl, alkenyl or C6-C18 aryl, R2 represents H, C1 to C10 alkyl, alkenyl or C6-C18 aryl, whereby R1 and R2 can be identical or different, X represents O or N[(A-0)m-R3], with the proviso that the entire R1-X structural unit can also represent N[(A-0)m-R3]2, R3 represents H, C1 to C10 alkyl, alkenyl or C6-C18 aryl, m represents a whole number between 0 and 500, A represents C2-C4 alkene and n represents a whole number between 1 and 900.

Description

description

Process for the desulfurization of crude oil fractionation products

The present invention relates to a process for the desulfurization of

Crude oil fractions such as gasoline, kerosene, diesel fuel, gas oil and heating oil by extraction using polyalkylene glycol dialkyl ethers.

In order to meet the requirements for low-pollution and more economical engines, and in view of increasingly stringent environmental regulations, it is necessary to reduce the sulfur content of crude oil distillates. The requirements for petrol and diesel fuel are regulated in DIN EN 228 and DIN EN 590, those for heating oil in DIN 51603. From 2000 the sulfur content in the EU was 150 ppm for gasoline and 350 ppm for diesel fuel, from 2005 50 ppm for both. Petrol denotes the fraction boiling from 35 ° C to 210 ° C, kerosene the fraction boiling from 100 ° C to 300 ° C, diesel fuel the fraction boiling from 200 ° C to 360 ° C, gas oil that from 200 ° C to 400 ° C boiling fraction.

State of the art for the desulfurization of crude oil distillates is treatment with hydrogen and catalysts ("hydrotreating"), degradation of the sulfur-containing compounds with special bacteria, treatment with solid adsorbents, treatment with oxygen-containing gases, catalysts and radiation, and chemical conversion of the sulfur-containing compounds to higher-boiling products The sulfur-containing compounds are, in particular, derivatives of thiophene, such as substituted and unsubstituted benzo- and dibenzothiophenes, mercaptans and others.

Disadvantages of the known processes are in general the high expenditure of energy, deactivation of the catalysts, low throughputs (in the biological processes) and the poor selectivity. To reach very low

Sulfur contents require large amounts of hydrogen, which can no longer be generated by the refining process itself, but must be produced separately. This worsens the Energy balance continues and large amounts of the greenhouse gas C0 ₂ are released. In addition, the catalytic reduction of the sulfur compounds releases H ₂ S, which must be converted to elemental sulfur in a further process step.

It is known that polyalkylene glycol dialkyl ethers, which are also known as "Glymes", are excellent solvents for many organic and inorganic compounds. However, certain Glymes are not or only very poorly miscible with aliphatic, nonpolar hydrocarbons Known that polyalkylene glycol dimethyl ether can be used to remove gaseous sulfur-containing compounds such as H ₂ S, mercaptans, COS, S0 ₂ and others from gas streams.

US 4,581,154 discloses that polyethylene glycol dimethyl ether having 3 to 8 ethylene oxide units is suitable for removing acidic components from gases at temperatures below freezing.

DE-B-20 28 456 discloses a mixture of homologous polyethylene glycol dimethyl ether with 3 to 9 ethylene oxide units and the use thereof as a solvent for separating acid gases from gas mixtures.

US-3,594,985 discloses a process for separating acid gases from gas mixtures, the gas mixture being brought into contact with a mixture of polyethylene glycol dimethyl ether.

The object on which the present invention is based was therefore to find a process for the desulfurization of crude oil fractions which circumvents the disadvantages mentioned.

Surprisingly, it has now been found that polyalkylene glycol dialkyl ethers have excellent solubility properties for the sulfur-containing constituents of the crude oil fractions to be removed. Are at the same time Polyalkylene glycol dialkyl ether immiscible with aliphatic hydrocarbons, the main components of crude oil distillates. The invention thus relates to a process for removing sulfur-containing compounds from crude oil fractionation products which have boiling points from 30 ° C. to 400 ° C. by using an extracting agent of the formula (1)

R ¹ - X- -A— O- R ² (1)

wherein

R ¹ H, C to CIO alkyl, C ₂ - to C ₂₀ alkenyl or C ₆ -C ₈ aryl, R ² H, C to CIO alkyl, C ₂ - to C ₂₀ alkenyl or C ₆ -Cι _8- aryl, where R ¹ and R ^{2 may be the} same or different,

XO or N [(AO) _m -R ³ ], with the proviso that the entire R ¹ -X structural unit can also stand for N [(A-0) _m -R ³ ] ₂ ,

R ^{3 is} H, d- to Cio-alkyl, C ₂ - to C ₂₀ -alkenyl or C ₆ -C ₈ -aryl, m is an integer from 0 to 500,

AC ₂ -C ₄ alkylene, n is an integer from 1 to 900, so that it contacts the product to be desulfurized so that the

Transfer sulfur compounds into the extractant.

Another object of the invention is the use of compounds of

Formula 1 as an extractant for the extractive desulfurization of products from

Rohölfraktionierung.

The crude oil fractionation products include gasoline (boiling range 35 ° C - 210 ° C), diesel fuel (boiling range 200 ° C to 360 ° C), kerosene (boiling range 100 ° C - 290 ° C) and gas oil (boiling range 200 ° C to 400 ° C).

A preferably represents an ethylene or propylene radical, in particular an ethylene radical. n is preferably between 1 and 240, in particular between 2 and 80. The alkoxy chain can be a block copolymer chain which has alternating blocks of different alkoxy units, preferably ethoxy and propoxy units. However, it can also be a chain with a statistical sequence of the alkoxy units.

X is preferably oxygen.

R ¹ and R ² independently of one another preferably represent d- to CQ-alkyl or C ₂ - to C ₆ -alkenyl or C ₆ -C ₂ -aryl, which can optionally be substituted by dC ₄ -alkyl, in particular methyl , Ethyl, propyl or butyl.

R ³ is preferably C ₂ -Cs-alkyl or alkenyl, provided that it means alkyl or alkenyl. If R ^{3 is} aryl, it is preferably C ₆ -C ₂ -aryl, which may optionally be substituted with dC ₄ -alkyl, and is preferably between 1 and 240, in particular between 2 and 80.

If R ¹ -X stands for N [(A-0) _m -R ³ ] ₂ , the compounds have the following structure:

The polyalkylene glycol dialkyl ethers are preferably polyethylene glycol dialkyl ethers, in particular polyethylene glycol dimethyl ether.

The extractive process can be carried out continuously or batchwise.

In both cases, the fraction to be desulfurized (distillate) is mixed intensively with the polyalkylene glycol dialkyl ether in the first step. This involves extracting the sulfur-containing compounds from the distillate into the Extractant, the glyme, instead. In the following stage, the phases are separated, one phase containing the distillate with a reduced sulfur content and the other phase containing the extractant enriched with sulfur. Typically, the sulfur content of the distillate is reduced by 20-30% per extraction step. To further reduce the sulfur content, the distillate can be subjected to further extraction steps.

Water is added to remove the sulfur-containing compounds from the extractant. A phase is formed which, in addition to the portions of distillate carried along during the extraction, contains the extracted sulfur, and an almost sulfur-free glyme-water mixture. The sulfur-containing phase can now be disposed of, worked up further or sent to a catalytic desulfurization. The advantage is that the sulfur-containing compounds are highly enriched in a small volume of distillate, making catalytic desulfurization much more efficient. In addition, the extractant mainly extracts the volatile hydrocarbons from the gasoline, which, when catalytically desulfurizing these extracted, now high-sulfur parts of the distillate has the further advantage that the catalyst has a longer service life.

In the next step, the extractant is freed from the water by distillation, preferably by means of a thin-film evaporator. The advantage here is that the extractant has a high boiling point and thus no distillation losses occur. Another advantage of the process is the high chemical and thermal resistance of the polyalkylene glycol dialkyl ethers.

This guarantees the almost unlimited reusability of the extractant.

When the process is carried out continuously, the extraction takes place in a continuous extractor such as, for example, an extraction column or a mixer settler. Using the mixer settler has the advantage that extraction and phase separation take place in one step. The phase separation results in a low-sulfur gasoline fraction and a sulfur-rich glyme fraction. For further desulfurization, a partial stream of the gasoline fraction can be extracted to be led back. To regenerate the extractant, the glyme fraction is mixed with water in a mixer-settler. The upper phase, which contains a lot of sulfur, is separated and can be further processed. The water-containing glyme phase is dewatered via a falling film evaporator and the extractant regenerated in this way is returned to the extraction.

Examples

Example 1 Batch extraction of gas oil with polyglycol DME 500

A typical gas oil with a sulfur content of 960 ppm was used. 200 g of the gas oil were shaken vigorously with 150 g of polyglycol DME 500 (500 polyethylene glycol dimethyl ether with medium molecular weight 500, Clariant GmbH) in a separating funnel for 3 minutes. The lower phase (extractant

Polyglycol DME 500) was separated. The upper phase (gas oil) now had a sulfur content of 670 ppm, which corresponds to a reduction of 30%. In a second separating funnel, the now sulfur-containing polyglycol DME 500 was mixed with 40 g of water. After shaking for a minute, a small amount of the upper phase forms. An analysis of the upper phase showed that the

Hydrocarbon distribution of the original gas oil was shifted to the low boiling range. The sulfur content of the upper phase was approximately 280 ppm, that of the extractant <10 ppm.

Example 2

Continuous extraction with polyglycol DME 500

The same gas oil as described in Example 1 was used. A small mixer-settler was charged with 50 l / h of polyglycol DME 500 (polyethylene glycol dimethyl ether with medium molecular weight 500, Clariant GmbH) and 70 l / h of gas oil. Two product streams were created. Stream A with the now sulfur-containing extractant and Stream B with the desulfurized gas oil. Stream B is collected in a storage vessel. The analysis showed one Sulfur content of 660 ppm, which corresponds to a desulfurization of 31%. Stream A was mixed with water in a second mixer-settler. Two product streams C and D were formed. Product stream C consisted of a small amount of a gasoline fraction with a high sulfur content which was disposed of. Stream D consisted of the water-containing polyglycol DME 500. Stream D was continuously dewatered using a thin-film evaporator. A regenerated polyglycol DME 500 with a water content of 0.1% and a sulfur content of <10 ppm was obtained.

Example 3

The same gas oil as described in Example 1 was used.

In a separatory funnel, 200 g of this gas oil were shaken intensively with 170 g of tris-methyltriglycolamine N ((CH ₂ -CH ₂ -0) ₃ ) for 3 minutes. The lower phase (extractant tris-methyltriglycolamine) was separated off. The upper phase (gas oil) now had a sulfur content of 650 ppm, which corresponds to a reduction of 32%. The sulfur-containing tris-methyltriglycolamine was mixed with 50 g of water in a second separating funnel. After shaking for a minute, a small amount of the upper phase forms. An analysis of the upper phase showed that the hydrocarbon distribution of the original gas oil was shifted to the low-boiling range. The sulfur content of the upper phase was approximately 300 ppm, that of the extractant <10 ppm.

Claims

claims:

1. Process for removing sulfur-containing compounds from crude oil fractionation products which have boiling points from 30 to 400 ° C. by using an extracting agent of the formula (1)

R ¹ - X - - o- R ² (1)

wherein R ^{1 is} H, d- to Cio-alkyl, C ₂ - to C ₂₀ -alkenyl or C ₆ -C ₈ -aryl, RH, d- to Cio-alkyl, C ₂ - to C ₂₀ -alkenyl or C ₆ - C ₁₈ aryl, where R ¹ and R ^{2 may be the} same or different,

XO or N [(A-0) mR ³ ], with the proviso that the entire

R ¹ -X structural unit can also stand for N [(A-0) _m -R ³ ] ₂ ,

R- H, d- to Cio-alkyl, C ₂ - to C ₂₀ alkenyl or C ₆ -C ₈ aryl, m is an integer from 0 to 500, AC ₂ -C ₄ alkylene, n is an integer from 1 to 900 mean in contact with the product to be desulfurized so that the sulfur compounds pass into the extractant.

2. The method according to claim 1, wherein formula (1) for a compound of formula

stands.

3. The method according to claim 1 and / or 2, wherein A represents an ethylene or propylene radical.

4. The method according to one or more of claims 1 to 3, wherein n is between 1 and 240.

5. The method according to one or more of claims 1 to 4, wherein R ¹ and / or R ^{2 are} C to C ₆ alkyl, C ₂ to C ₆ alkenyl or C ₆ to C ₂ aryl.

6. Use of compounds of formula 1 as an extractant for the extractive desulfurization of crude oil fractionation products which have boiling points from 30 to 400 ° C.