JP2018119151A - Method of removing sulphur-containing compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of removing a sulphur-containing compound in which carbon disulfide and mercaptan contained in hydrocarbons are removed and capable of contributing to quality improvement of a product obtained by distillation refinement in a post-process stage.SOLUTION: A method of obtaining refined hydrocarbons sulphur-containing compound content of which is lowered, includes steps of: introducing a mixture of an amide compound and an aqueous nitrite solution from a pipeline 1 disposed in a side face upper part of a contact container 3 and crude hydrocarbons containing carbon disulfide and mercaptan from a pipeline 2 disposed in a side face lower part of the contact container 3; bringing those compounds into contact with each other; separating a hydrocarbon fraction from the amide compound and the nitrite by distillation; and taking out the refined hydrocarbons from a pipeline 4 disposed at a top part of the contact container 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for removing sulfur-containing compounds, and more specifically, carbon disulfide and mercaptans contained in hydrocarbons are removed, and in a subsequent process, the content of the products obtained by distillation purification can be improved. The present invention relates to a method for removing sulfur compounds.

  In recent years, various hydrocarbon fractions by-produced in the process of producing naphtha and the like by cracking naphtha may be accompanied by a larger amount of components derived from sulfur compounds contained in the raw material than in the past. . Among them, the C5 fraction mainly composed of hydrocarbons having 5 carbon atoms is accompanied by sulfur-containing compounds such as carbon disulfide, mercaptans, and dimethyl sulfide having a boiling point close to that of the C5 fraction, and particularly carbon disulfide and mercaptans. May be contained in large quantities. When the content of this sulfur-containing compound is large, sulfur-containing compounds are mixed in isoprene, piperylene, dicyclopentadiene, etc. obtained by refining from the C5 fraction, and when producing rubbers and resins using these as raw materials, a polymerization reaction is performed. It is necessary to remove the sulfur-containing compound because it impedes or odors the product.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-281602) discloses a method of removing carbon disulfide by bringing a hydrocarbon containing carbon disulfide into contact with a polyvalent amine and alkaline water.

JP 2005-281602 A

  However, in the method disclosed in Patent Document 1, when application to an industrial process is considered, further improvement is demanded from the viewpoint that the cost of equipment for wastewater treatment increases. Moreover, it was insufficient for removing mercaptans contained in hydrocarbons.

  The present invention has been made in view of the prior art as described above, and provides a method for easily and efficiently removing sulfur-containing compounds, particularly carbon disulfide and mercaptans, from hydrocarbons containing sulfur-containing compounds. It is intended to provide.

  As a result of repeated studies to solve the above-mentioned problems, the present inventors brought carbon disulfide and mercaptans into contact with hydrocarbons containing carbon disulfide and mercaptans by contacting them with amide compounds and nitrites. The inventors have found that it can be easily removed, and have completed the present invention.

The gist of the present invention is as follows.
(A) A method for removing a sulfur-containing compound, comprising a step of bringing a crude hydrocarbon containing one or more sulfur-containing compounds selected from the group consisting of carbon disulfide and mercaptans into contact with an amide compound and nitrite.
(B) A method for producing purified hydrocarbons, including the method for removing a sulfur-containing compound according to (A).

  According to the method for removing sulfur-containing compounds of the present invention, sulfur-containing compounds contained in hydrocarbons, particularly carbon disulfide and mercaptans, can be easily and efficiently removed, and products obtained by distillation purification in the subsequent steps. It becomes possible to improve quality.

1 shows a schematic configuration of an apparatus used in the present invention.

  Hereinafter, the present invention will be described in more detail. The sulfur-containing compound removal method of the present invention includes a step of bringing a crude hydrocarbon containing one or more sulfur-containing compounds selected from the group consisting of carbon disulfide and mercaptans into contact with an amide compound and nitrite.

  The crude hydrocarbon generally contains various sulfur-containing compounds in the hydrocarbon. In the present invention, among these sulfur-containing compounds, carbon disulfide and mercaptans are targeted for removal.

  The crude hydrocarbon is not particularly limited, but is preferably a C4 fraction mainly containing a hydrocarbon having 4 carbon atoms or a C5 fraction mainly containing a hydrocarbon having 5 carbon atoms. These crude hydrocarbons are, for example, fractions produced as a by-product in the process of cracking naphtha to produce ethylene and the like.

  Among these, the method of the present invention is particularly effective for crude hydrocarbons mainly composed of C5 fraction, which have close boiling points to carbon disulfide and mercaptans and are difficult to separate from carbon disulfide and mercaptans. It is.

  Examples of the hydrocarbon having 4 carbon atoms contained in the C4 fraction include 1,3-butadiene, n-butane, isobutane, 1-butene, 2-butene, isobutene, and vinylacetylene. On the other hand, examples of the hydrocarbon having 5 carbon atoms contained in the C5 fraction include isoprene, isoamylene, amylene, n-pentane, isopentane, piperylene, cyclopentane, cyclopentene, and cyclopentadiene.

  Examples of mercaptans which are a kind of sulfur-containing compounds include chain mercaptans and cyclic mercaptans. The number of carbon atoms of the mercaptans is preferably 20 or less, more preferably 1 to 15 and even more preferably 1 to 10.

  Examples of such chain mercaptans include methyl mercaptan, ethyl mercaptan, normal propyl mercaptan, and isopropyl mercaptan. Examples of cyclic mercaptans include cyclopentyl mercaptan, cyclohexyl mercaptan, 2-methylcyclopentyl mercaptan, and 3-methylcyclopentyl mercaptan. Can be mentioned. Among these, ethyl mercaptan is particularly preferred as a sulfur-containing compound to be treated by the removal method of the present invention because it has a boiling point close to that of isoprene, which is one of the objects to be purified by distillation. Mercaptans may be contained in crude hydrocarbons in one or more kinds.

  The crude hydrocarbon to be treated in the present invention is not particularly limited as long as it is a hydrocarbon containing carbon disulfide and / or mercaptans, but the total of carbon disulfide and mercaptans is preferably 10,000 ppm. Hereinafter, it is more preferably 1,000 ppm or less, particularly preferably 500 ppm or less. Further, the total content of carbon disulfide and mercaptans is preferably 1 ppm or more. When the total amount of carbon disulfide and mercaptans is within the above range, the sulfur-containing compound can be efficiently removed.

  Examples of the amide compound used in the present invention include a chain amide compound and a cyclic amide compound. Carbon number of an amide compound becomes like this. Preferably it is 20 or less, More preferably, it is 3-15, More preferably, it is 3-10.

  Examples of the chain amide compound include N, N-dimethylformamide, N-methyl-N-phenylformamide, N, N-diphenylformamide, N, N-dimethylacetamide, N-methyl-N-phenylacetamide, N, N- Diphenylacetamide, N, N-diethylformamide, N-ethyl-N-phenylformamide, N, N-diethylacetamide, N-ethyl-N-phenylacetamide and the like, and cyclic amide compounds include N-methylpyrrolidone, N-ethylpyrrolidone, N-methylpiperidinone, N-ethylpiperidinone and the like can be mentioned. Among these, a chain amide compound is preferable, and from the viewpoint of operability, a chain amide compound that is liquid at 50 ° C. and 1 atm is more preferable, and N, N-dimethylformamide is more preferable. The amide compounds may be used alone or in combination of two or more.

  Examples of the nitrite used in the present invention include alkali metal nitrite and alkaline earth metal nitrite. Specific examples of the alkali metal nitrite include sodium nitrite and potassium nitrite, and specific examples of the alkaline earth metal nitrite include magnesium nitrite and calcium nitrite. Among these, from the viewpoint of solubility, alkali metal nitrites are preferable, sodium nitrite and potassium nitrite are more preferable, and sodium nitrite is particularly preferable.

  Nitrite may be used in a salt state, but from the viewpoint of solubility, when mixed with an amide compound, it may be dissolved in water and used as an aqueous solution. When nitrite is dissolved in water and then mixed with the amide compound, the nitrite is easily dissolved in the amide compound. In the case of an aqueous solution, the concentration of nitrite is not particularly limited as long as it is dissolved in water, but it is preferably 50% by weight or less, particularly preferably 20% by weight or less.

  In the present invention, the method of bringing the crude hydrocarbon containing carbon disulfide and mercaptans into contact with the amide compound and nitrite is not particularly limited, but (a) the crude hydrocarbon and amide compound containing carbon disulfide and mercaptans And (b) a method in which nitrite is mixed with an amide compound and then a carbon dioxide disulfide and a crude hydrocarbon containing a mercaptan are brought into contact with each other. From the viewpoint of the ability to remove mercaptans, the method (b) is preferred. Further, both the methods (a) and (b) may be either a continuous type or a batch type.

  The amount ratio between the amide compound and the crude hydrocarbon in the contacting step (hereinafter, sometimes simply referred to as “contacting step”) is not particularly limited, but is preferably a weight ratio (amide compound / crude hydrocarbon) of preferably 0.1. The ratio is 1/1 to 100/1, more preferably 0.5 / 1 to 50/1, and particularly preferably 1/1 to 10/1. If the quantitative ratio of the amide compound and the crude hydrocarbon is within the above range, the sulfur-containing compound can be sufficiently removed.

  The amount of nitrite used in the contacting step is not particularly limited, but is preferably 0.01 to 1,000 ppm, more preferably 0.1 to 100 ppm, and particularly preferably 0.5 to 50 ppm in the amide compound. . When the amount of nitrite added is within the above range, the nitrite can be sufficiently dissolved in the amide compound, and the sulfur-containing compound can be efficiently removed.

  Further, the amount ratio of nitrite to carbon disulfide is not particularly limited, but is preferably 0.01 / 1 to 100/1, more preferably 0.02 / in molar ratio (nitrite / carbon disulfide). 1 to 50/1, particularly preferably 0.03 / 1 to 30/1. The amount ratio of nitrite to mercaptans is not particularly limited, but is preferably a molar ratio (nitrite / mercaptans). It is 0.1 / 1 to 100/1, more preferably 0.2 / 1 to 50/1, and particularly preferably 0.3 / 1 to 30/1. When the amount of nitrite added is in the above range, the sulfur-containing compound can be sufficiently removed.

  Although the temperature in a contact process is not specifically limited, Preferably it is 0-250 degreeC, More preferably, it is 10-200 degreeC. If the contact temperature is too low, the sulfur-containing compounds may not be removed sufficiently. If the temperature is too high, unsaturated hydrocarbons in the crude hydrocarbon will undergo a polymerization reaction, etc., producing high molecular weight compounds and reducing product yield. May be invited. For example, when isoprene is contained in the crude hydrocarbon, if the temperature at the time of contact is too high, a dimer of isoprene and the like may be produced, and the yield of isoprene may be reduced.

  Moreover, a contact process may be implemented by a normal pressure and may be implemented under the pressurization of about 0-3 Mpa. Although the time to contact is not specifically limited, Preferably it is 1 second-300 minutes, More preferably, it is about 1 minute-180 minutes.

  The reason why carbon disulfide and mercaptans in the crude hydrocarbon are removed by contact with the amide compound and nitrite is not theoretically restricted, but is considered as follows. That is, in the above contact step, it is considered that carbon disulfide and mercaptans react with the amide compound and nitrite to be converted into a low-boiling sulfur-containing compound or a high-boiling sulfur-containing compound. As a result, during or after the contacting step, the low boiling point sulfur-containing compound is volatilized through the distillation operation, preferably through the distillation step, and the high boiling point sulfur-containing compound is converted into a liquid or salt and separated as a residue, It is thought that carbon disulfide and mercaptans in the crude hydrocarbon are removed.

  FIG. 1 shows a preferred embodiment of the method for removing carbon disulfide and mercaptans of the present invention, but the present invention is not limited to this embodiment. In the embodiment of FIG. 1, a mixture of an amide compound and an aqueous nitrite solution is introduced from the pipe 1 at the upper side of the contact vessel 3, and a crude hydrocarbon containing carbon disulfide and mercaptans is introduced from the pipe 2 at the lower side. After contacting them in the contact vessel 3, the hydrocarbon fraction is separated from the amide compound and nitrite by distillation, and the purified hydrocarbon having a reduced content of sulfur-containing compounds is removed from the top pipe 4 of the contact vessel 3. obtain. Separation conditions are not particularly limited, but when the C5 fraction is separated, purified hydrocarbons are obtained from the top pipe 4 through a distillation step of keeping the liquid temperature at about 120 to 160 ° C. after the contact step.

  As the contact vessel, it is preferable to use a pressure vessel equipped with a stirrer and a circulation device. After performing the above contact step in a pressure vessel, the pressure is released to obtain a purified hydrocarbon in which the content of carbon disulfide and mercaptans is reduced from the top pipe 4.

  Moreover, since the effluent from the bottom pipe 5 of the container 3 contains unreacted amide compound, nitrite, and various additives, these may be recovered and reused.

  In the case of removing carbon disulfide and mercaptans in the manner shown in FIG. 1, furfural, methylfurfural, hydroxymethylfurfural, thiophenecarbaldehyde, nicotine are added as additives to the amide compound in order to suppress contamination of the contact vessel 3 Heterocyclic polar compounds such as aldehyde and pyridoxal; aromatic nitro compounds such as nitrobenzene, nitrotoluene, nitroxylene, nitromesitylene, dinitrobenzene and trinitroxylene; benzaldehyde, tolaldehyde, cuminaldehyde, phenylacetaldehyde, cinnamaldehyde, phthalaldehyde Aromatic aldehydes such as isophthalaldehyde and terephthalaldehyde; Among these, furfural, nitrobenzene, and benzaldehyde are preferable, and furfural is particularly preferable.

  The addition amount of these additives is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 15 parts by weight with respect to 100 parts by weight of the amide compound.

  The crude hydrocarbon is brought into contact with the amide compound and nitrite, and then separated from the amide compound and nitrite, and then subjected to a distillation step to recover, so that the total content of carbon disulfide and mercaptans contained in the resulting purified hydrocarbon is contained. The amount is reduced, preferably 300 ppm or less, more preferably 100 ppm or less, particularly preferably 50 ppm or less, and to a value lower than the total content of carbon disulfide and mercaptans in the crude hydrocarbon.

  As described above, in the method for removing a sulfur-containing compound according to the present invention, preferably, the crude hydrocarbon is a C4 fraction or a C5 hydrocarbon mainly comprising a C4 hydrocarbon. C5 fraction as the main component.

  In the method for removing a sulfur-containing compound according to the present invention, preferably, the crude hydrocarbon is separated from the amide compound and the nitrite after the step of contacting the crude hydrocarbon with the amide compound and the nitrite, and the content of the sulfur-containing compound is determined. The method further includes a distillation step of recovering the purified hydrocarbon with reduced slag.

  In the method for removing a sulfur-containing compound according to the present invention, preferably, the sulfur-containing compound content in the crude hydrocarbon is 1 ppm or more and 10,000 ppm or less, and the sulfur-containing compound content in the purified hydrocarbon is 300 ppm or less. And it is a value lower than the sulfur-containing compound content in the crude hydrocarbon.

  In addition, the method for producing a purified hydrocarbon according to the present invention preferably includes the above-described method for removing a sulfur-containing compound.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples. In the examples and comparative examples, “parts”, “%”, and “ppm” are based on mass unless otherwise specified. Moreover, the sulfur-containing compound content in crude hydrocarbons and refined hydrocarbons was measured using the following equipment and conditions.

Equipment GC7890 made by Agilent
Column DB-1 length 30m, inner diameter 0.32mm, film thickness 0.25μm)
Column temperature held at 40 ° C for 10 minutes, then heated up at 10 ° C per minute, held at 250 ° C for 3 minutes Inlet temperature 140 ° C
Carrier gas helium (flow rate 1.17ml / min)
Detector Agilent 355 Sulfur Chemiluminescence Detector (SCD)

<Example 1>
Crude C5 distillate containing 13.3 ppm carbon disulfide and 2.0 ppm ethyl mercaptan in a stainless steel pressure vessel equipped with a stirrer (composition: C4 (carbon number 4 hydrocarbon) 2.1%, normal pentane 22. 0%, isopentane 20.1%, amylene 6.9%, isoamylene 7.4%, 1,4-pentadiene 1.5%, isoprene 15.6%, piperylene 10.6%, cyclopentane 1.1%, 69.0 parts of cyclopentene 2.5%, cyclopentadiene 6.6%, C6 (C6 hydrocarbon) 3.6%), dimethylformamide 97.4%, furfural 2.6%, nitrous acid 323.6 parts of a solution containing 0.7 ppm of sodium was charged. The mixture solution of the two liquids was heated to 120 ° C. with stirring and held for 1 hour, and then the gaseous C5 fraction was extracted from the upper part of the container while maintaining the liquid temperature at 120 ° C. to 160 ° C. 67.6 parts of purified C5 fraction containing 9.8 ppm carbon and 1.3 ppm ethyl mercaptan was obtained. Further, 309.3 parts of a solution containing neither carbon disulfide nor ethyl mercaptan remained in the container. As a result, 27.8% of carbon disulfide and 36.3% of ethyl mercaptan contained in the crude C5 fraction were removed.

<Comparative Example 1>
A crude C5 fraction containing 26.9 ppm carbon disulfide and 1.8 ppm ethyl mercaptan in a stainless steel pressure vessel equipped with a stirrer (composition: C4 (carbon number 4 hydrocarbon) 2.1%, normal pentane 22. 0%, isopentane 20.1%, amylene 6.9%, isoamylene 7.4%, 1,4-pentadiene 1.5%, isoprene 15.6%, piperylene 10.6%, cyclopentane 1.1%, Containing 64.4 parts of cyclopentene 2.5%, cyclopentadiene 6.6%, C6 (hydrocarbon having 6 carbon atoms) 3.6%, dimethylformamide 97.4% and furfural 2.6%. 303.3 parts of a solution containing no sodium nitrate was charged. The mixture solution of the two liquids was heated to 120 ° C. with stirring and held for 1 hour, and then the gaseous C5 fraction was extracted from the upper part of the container while maintaining the liquid temperature at 120 ° C. to 160 ° C. 63.9 parts of C5 fraction containing 27.1 ppm of carbon and 1.8 ppm of ethyl mercaptan was obtained. Further, 288.6 parts of a solution containing neither carbon disulfide nor ethyl mercaptan remained in the container. As a result, carbon disulfide contained in the crude C5 fraction was not removed, and ethyl mercaptan was also removed by 0.8%.

<Example 2>
In a stainless steel pressure vessel equipped with a stirrer, a crude C5 distillate containing 149.6 ppm of carbon disulfide and 13.4 ppm of ethyl mercaptan (composition: isoprene 94.1%, 2-butyne 2.8%) is 8.6. 46.4 parts of a solution containing 96.1% dimethylformamide, 3.9% furfural, and 8.9 ppm sodium nitrite. The mixed solution was heated to 120 ° C. with stirring and held for 1 hour, and then the gaseous C5 fraction was withdrawn from the upper part of the vessel while maintaining the liquid temperature at 120 ° C. to 160 ° C. 8.6 parts of a purified C5 fraction containing 0.2 ppm and 9.1 ppm of ethyl mercaptan were obtained. Further, 42.1 parts of a solution containing neither carbon disulfide nor ethyl mercaptan remained in the container. As a result, 87.2% of carbon disulfide and 32.1% of ethyl mercaptan contained in the crude C5 fraction were removed.

<Example 3>
9.6 of a crude C5 fraction containing 34.0 ppm carbon disulfide and 9.0 ppm ethyl mercaptan (composition: isoprene 94.1%, 2-butyne 2.8%) in a stainless steel pressure vessel equipped with a stirrer. 51.8 parts of a solution containing 96.1% of dimethylformamide, 3.9% of furfural and 3.3 ppm of sodium nitrite. The mixture solution of the two liquids was heated to 120 ° C. with stirring and held for 1 hour, and then the gaseous C5 fraction was extracted from the upper part of the container while maintaining the liquid temperature at 120 ° C. to 160 ° C. 9.6 parts of a purified C5 fraction containing 8.3 ppm of carbon and 5.7 ppm of ethyl mercaptan was obtained. Further, 45.2 parts of a solution containing neither carbon disulfide nor ethyl mercaptan remained in the container. As a result, 75.6% of carbon disulfide and 36.7% of ethyl mercaptan contained in the crude C5 fraction were removed.
The above results are summarized in the table below.

1 ... Side upper pipe 2 ... Side lower pipe 3 ... Contact container (pressure vessel)
4 ... Top piping 5 ... Bottom piping

Claims (7)

  A process comprising: contacting a crude hydrocarbon containing one or more sulfur-containing compounds selected from the group consisting of carbon disulfide and mercaptans with an amide compound containing 0.5 to 50 ppm of nitrite. Removal method.   2. The method for removing a sulfur-containing compound according to claim 1, wherein the crude hydrocarbon is a C4 fraction mainly containing a hydrocarbon having 4 carbon atoms or a C5 fraction mainly containing a hydrocarbon having 5 carbon atoms.   The method further comprises a distillation step of separating the crude hydrocarbon from the amide compound and nitrite after the step of contacting the crude hydrocarbon with the amide compound and nitrite, and recovering a purified hydrocarbon having a reduced content of sulfur-containing compounds. 2. The method for removing a sulfur-containing compound according to 1.   The method further comprises a distillation step of separating the crude hydrocarbon from the amide compound and nitrite after the step of contacting the crude hydrocarbon with the amide compound and nitrite, and recovering a purified hydrocarbon having a reduced content of sulfur-containing compounds. 2. The method for removing a sulfur-containing compound according to 2.   The sulfur-containing compound content in the crude hydrocarbon is 1 ppm or more and 10,000 ppm or less, the sulfur-containing compound content in the refined hydrocarbon is 300 ppm or less and a value lower than the sulfur-containing compound content in the crude hydrocarbon. Item 4. A method for removing a sulfur-containing compound according to Item 3.   The sulfur-containing compound content in the crude hydrocarbon is 1 ppm or more and 10,000 ppm or less, the sulfur-containing compound content in the refined hydrocarbon is 300 ppm or less and a value lower than the sulfur-containing compound content in the crude hydrocarbon. Item 5. A method for removing a sulfur-containing compound according to Item 4.   The manufacturing method of the refinement | purification hydrocarbon containing the removal method of the sulfur-containing compound of any one of Claims 3-6.

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