Method for preparing 1-pentene and co-producing isopentene and tert-amyl alcohol from coal chemical C5

Abstract

The invention provides a method for preparing 1-pentene and co-producing isopentene and tert-amyl alcohol from C5 in the coal chemical industry, and relates to the technical field of comprehensive utilization of mixed C5. The method comprises the following steps: carrying out heavy component removal treatment on the coal chemical C5 fraction, carrying out light component removal treatment on the tower top fraction, mixing the tower kettle material with water and a solvent, feeding into a fixed bed filled with strong acid cation exchange resin, carrying out hydration reaction, rectifying the hydration product, and introducing the tower top material into a catalytic distillation tower filled with a double-bond isomerization catalyst, a material rich in 2-methyl-2-butene is obtained from the tower kettle, 2-methyl-2-butene is obtained through rectification, the tower kettle material obtained after the hydration product is rectified is subjected to azeotropic rectification, an entrainer and tert-amyl alcohol on the upper layer participate in reflux, and tert-amyl alcohol and a solvent are obtained from the tower kettle. According to the method disclosed by the invention, three products of 1-pentene, isopentene and tert-amyl alcohol can be obtained at one time, the price of the used catalyst is low, the reaction conditions are mild, and qualified products can be obtained by adopting a common distillation mode for most of the products.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of mixed C5, and in particular to a method for preparing 1-pentene and co-producing isopentene and tert-amyl alcohol from C5 in coal chemical industry. Background Art

[0002] Coal chemical C5 contains 6-7% 1-pentene and 24-25% isopentene. Currently, the comprehensive utilization of C5 fractions is mainly to separate the C5 fractions to obtain high-value diolefins such as isoprene, dicyclopentadiene and isopentane, as well as isopentene products. The boiling points of the components in C5 are very close, making separation difficult. They are generally only used as fuel oil or obtained through full hydrogenation to obtain a mixture of pentane and isopentane, with low added value.

[0003] Low molecular weight oligomers of 1-pentene are excellent fuel and lubricant additives. They can also serve as catalyst additives in various reactions and oxidation reactions to produce 1,2-pentanediol, which can be further used to prepare the highly effective, low-toxic, broadly active fungicide propiconazole. 1-Pentene is also a high-value-added fine chemical intermediate. Due to its unique double bond position and spatial structure, it is an important monomer for polymer material modification, the synthesis of complex organometallic compounds, and pharmaceutical synthesis. 1-Pentene can also be hydroformylated to produce the more industrially valuable 1-hexene product. Isoamylene is an important fine chemical product used in the production of pinacolone, tert-amyl alcohol, and as a comonomer in polymerization. Tert-amyl alcohol is a basic organic chemical raw material used in the production of pinacolone, tert-amylbenzene, and tert-amylanthraquinone (2-amylanthraquinone), and in the synthesis of galaxol and color film colorants. Tert-amyl alcohol is also used as a solvent, plasticizer, and non-ferrous metal flotation agent.

[0004] Currently, the route for preparing 1-pentene, isopentene, and tert-amyl alcohol from mixed C5 has problems such as long process, low yield of target product, high reaction temperature, high energy consumption, corrosion to equipment, and large catalyst investment. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for producing 1-pentene and isopentene and tert-amyl alcohol from coal chemical industry carbon five. The method used in the present invention can obtain three products, 1-pentene, isopentene and tert-amyl alcohol, at one time. The catalyst used is low-priced, the reaction conditions are mild, and qualified products can be obtained by most ordinary distillation methods.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0007] The present invention provides a method for producing 1-pentene from C5 in coal chemical industry and co-producing isopentene and tert-amyl alcohol, comprising the following steps:

[0008] S1: The coal chemical C5 fraction is subjected to a weight removal treatment to obtain a fraction rich in isopentane, 1-pentene and 2-methyl-1-butene at the top of the tower;

[0009] S2: performing a light removal treatment on the top fraction obtained in step S1 to remove the C4 fraction, 3-methyl-1-butene, and most of the isopentane, and obtaining a mixture of 1-pentene and 2-methyl-1-butene in the bottom of the tower;

[0010] S3: mixing the bottom material obtained in step S2 with water and a solvent and then feeding the mixture into a fixed bed loaded with a catalyst for hydration reaction, wherein the catalyst is a strongly acidic cation exchange resin;

[0011] S4: distilling the hydration product obtained in step S3 to obtain a mixture of 1-pentene, 2-methyl-1-butene and 2-methyl-2-butene at the top of the tower, and obtaining tert-amyl alcohol, water and solvent at the bottom of the tower;

[0012] S5: passing the overhead material obtained in step S4 through a catalytic distillation column loaded with a double bond isomerization catalyst, thereby obtaining 1-pentene at the top and a material rich in 2-methyl-2-butene in the bottom of the column, wherein the double bond isomerization catalyst is a strongly acidic cation exchange resin modified with a metal ion;

[0013] S6: distilling the 2-methyl-2-butene-rich material obtained in step S5 to obtain 2-methyl-2-butene at the top of the tower and heavy components at the bottom of the tower;

[0014] S7: performing azeotropic distillation on the bottom material obtained in step S4 to obtain a mixture of an entrainer, tert-amyl alcohol, and water at the top of the tower. After separation, the water in the lower layer is returned to step S3 for recycling, and the entrainer and tert-amyl alcohol in the upper layer are refluxed to obtain tert-amyl alcohol and solvent in the bottom of the tower;

[0015] S8: The bottom material obtained in step S7 is distilled to obtain tert-amyl alcohol at the top of the tower and the solvent at the bottom of the tower, and the solvent is returned to step S3 for recycling.

[0016] In some embodiments, the operating pressure of step S1 is 0-0.1 MPa, the tower top temperature is 42-45° C., the tower bottom temperature is 62-65° C., the reflux ratio is 20-30, and the cis- and trans-pentene contents at the tower top are controlled to be ≤0.05%, and the 2-methyl-1-butene content in the tower bottom is controlled to be ≤0.5%.

[0017] In some embodiments, the operating pressure of step S2 is 0.15-0.2 MPa, the tower top temperature is 45-48° C., the tower bottom temperature is 65-70° C., the reflux ratio is 40-50, and the tower top 1-pentene content is controlled to be ≤0.5%, and the tower bottom 3-methyl-1-butene content is controlled to be ≤0.05%.

[0018] In some embodiments, the solvent in step S3 is a high boiling point solvent, which can be phenol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol monobutyl ether, etc., preferably ethylene glycol ethyl ether;

[0019] In some embodiments, the reaction pressure of step S3 is 1-1.5 MPa, and the weight hourly space velocity of the C5 feed (a mixture of 1-pentene and 2-methyl-1-butene) is 0.5-1 h -1 The reactor inlet temperature is 50-66°C, the reactor outlet temperature is 55-70°C, the mass ratio of solvent to C5 (a mixture of 1-pentene and 2-methyl-1-butene) is 2-3, the molar ratio of water to 2-methyl-1-butene is 3-4, the total isopentene conversion rate is 45-65%, and the selectivity of tert-amyl alcohol is ≥99.5%.

[0020] In some embodiments, the water and solvent in step S3 include fresh deionized water, water returned from step S7 , and solvent returned from step S8 .

[0021] In some embodiments, the operating pressure of step S4 is 0.05-0.1 MPa, the tower top temperature is 53-55° C., the tower bottom temperature is 123-126° C., the reflux ratio is 3-5, and the tower five fraction in the tower bottom is controlled to be ≤0.05%.

[0022] In some embodiments, the metal ions of the metal ion-modified strong acidic cation exchange resin in step S5 can be one or more of iron ions, copper ions, zinc ions, and nickel ions, preferably nickel ions, which are derived from nickel nitrate or nickel acetate. 2+ The molar ratio of the sulfonate ion to the strong acidic cation exchange resin is 5 to 10:50; the mass ratio of the amount of the metal ion modified strong acidic cation exchange resin to the feed amount of the tower is 1 to 3:10;

[0023] In some embodiments, the operating pressure of step S5 is 0.05-0.1 MPa, the tower top temperature is 45-48°C, the tower bottom temperature is 60-65°C, the reflux ratio is 8-15, the tower top isopentene content is controlled to be ≤0.5%, the 1-pentene content is controlled to be ≥98%, and the 1-pentene content in the tower bottom is controlled to be ≤0.1%.

[0024] In some embodiments, the operating pressure of step S6 is 0.05-0.1 MPa, the tower top temperature is 48-52° C., the tower bottom temperature is 90-95° C., the reflux ratio is 1-2, and the 2-methyl-2-butene content at the tower top is controlled to be ≥99%, and the 2-methyl-2-butene content in the tower bottom is controlled to be ≤0.1%.

[0025] In some embodiments, the azeotropic agent in step S7 can be benzene, toluene, n-hexane and cyclohexane, preferably n-hexane or cyclohexane, with an operating pressure of 0-0.05 MPa, a top temperature of 65-70° C., a bottom temperature of 125-128° C., and a reflux ratio of 10-15.

[0026] In some embodiments, the operating pressure of step S8 is 0-0.05 MPa, the tower top temperature is 105-108° C., the tower bottom temperature is 135-140° C., and the reflux ratio is 3-5.

[0027] Technical effects:

[0028] 1. The method for producing 1-pentene from coal chemical C5 and co-producing isopentene and tert-amyl alcohol provided by the present invention can appropriately adjust the output of isopentene and tert-amyl alcohol according to market demand, and the operation is flexible and changeable.

[0029] 2. The method for preparing 1-pentene provided by the present invention does not require hydrogenation reaction, and a high-purity 1-pentene product can be obtained through simple separation.

[0030] 3. The catalyst in the catalytic distillation tower provided by the present invention is modified by a simple method, thereby improving the yield of 1-pentene and isopentene.

[0031] 4. The method for synthesizing tert-amyl alcohol provided by the present invention has mild reaction conditions, high isopentene conversion rate and tert-amyl alcohol selectivity, and few side reactions.

[0032] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the method for producing 1-pentene and isopentene and tert-amyl alcohol from coal chemical C5 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0035] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art.

[0036] Example 1

[0037] The process flow of Example 1 is shown in Figure 1 The raw material is coal chemical C5 fraction, and its main composition is shown in Table 1.

[0038] Table 1

[0039] name Boiling point, °C content,% name Boiling point, °C content,% C4 ≤3.7 0.45 3-Methyl-1-butene 20.1 0.92 Isopentane 27.8 0.62 1.4-Pentadiene 25.9 0.04 1-Pentene 30.1 6.87 2-Methyl-1-butene 31.2 8.46 n-pentane 36.1 0.76 Isoprene 34.1 - transpentene 36.3 20.43 Cis-pentene 36.9 10.71 2-Methyl-2-butene 38.6 16.41 trans-1,3-pentadiene 42.0 1.2 Cyclopentadiene 41.5 0.98 cis-1,3-pentadiene 44.1 0.3 Cyclopentene 44.2 1.55 Cyclopentane 49 0.1 Other C5 and ≥C6 ≥54 30.2

[0040] The method for producing 1-pentene from C5 in coal chemical industry and co-producing isopentene and tert-amyl alcohol comprises the following steps:

[0041] The coal chemical C5 fraction pipeline 1 enters the heavy removal tower D1 for heavy removal treatment, removing the heavy components such as n-pentane, cis-pentene, trans-pentene, and 2-methyl-2-butene and then exits the system through pipeline 2. The fraction rich in isopentane, 1-pentene, and 2-methyl-1-butene is obtained at the top of the tower and enters the light removal tower D2 through pipeline 3 for light removal treatment;

[0042] The C4 fraction, 3-methyl-1-butene and isopentane obtained at the top of the light removal tower D2 are discharged from the system via pipeline 4, and the mixture of 1-pentene and 2-methyl-1-butene obtained at the bottom of the tower enters the hydration reactor R1 via pipeline 5;

[0043] The material from line 5 is mixed with fresh deionized water from line 6, recovered deionized water from line 14, and return solvent from line 17, and then enters a fixed-bed hydration reactor R1 loaded with a catalyst for hydration reaction (2-methyl-1-butene and water undergo hydration reaction to produce tert-amyl alcohol, and at the same time, there are also side reactions such as double bond isomerization reaction of 2-methyl-1-butene to produce 2-methyl-2-butene, intermolecular dehydration of tert-amyl alcohol to produce di-tert-amyl ether, dimerization of isopentene to produce C10 olefins), the catalyst is a strongly acidic cation exchange resin, and the solvent is ethylene glycol ethyl ether. The reaction product and unreacted C5 enter a C5 recovery tower D3 via line 7;

[0044] The mixture of 1-pentene, 2-methyl-1-butene and 2-methyl-2-butene obtained at the top of the C5 recovery tower D3 enters the catalytic distillation tower D4 via pipeline 8, and the tert-amyl alcohol, water and solvent obtained in the bottom of the tower enter the azeotropic distillation tower D6 via pipeline 9;

[0045] In the catalytic distillation tower D4, 2-methyl-1-butene undergoes a double bond isomerization reaction under the action of a double bond isomerization catalyst to produce 2-methyl-2-butene, which is separated by different boiling points. The 1-pentene product obtained at the top of the tower is discharged from the system via pipeline 10, and the material rich in 2-methyl-2-butene obtained in the bottom of the tower is fed into the isopentene refining tower D5 via pipeline 11.

[0046] The 2-methyl-2-butene product obtained at the top of the isopentene refining tower D5 is discharged from the system via pipeline 12, and the heavy components obtained at the bottom of the tower are discharged from the system via pipeline 13;

[0047] A mixture of entrainer, tert-amyl alcohol and water is obtained at the top of the azeotropic distillation tower D6. After stratification, the water in the lower layer is returned to the reactor for recycling via pipeline 14, and the entrainer and tert-amyl alcohol in the upper layer are refluxed. The tert-amyl alcohol and solvent obtained in the bottom of the tower are fed into the tert-amyl alcohol refining tower D7 via pipeline 15. The entrainer is cyclohexane.

[0048] Tert-amyl alcohol is obtained from the top of the tert-amyl alcohol refining tower D7, and the solvent obtained from the bottom of the tower is returned to the reactor for recycling through pipeline 17. Fresh solvent is replenished through pipeline 18, and excess solvent is discharged from the system through pipeline 19.

[0049] The preparation method of double bond isomerization catalyst is as follows:

[0050] 1) Take 10 kg of commercially available strong acid cation exchange resin (QSE-02 strong acid cation exchange resin from Zibo Rongke Chemical Technology Co., Ltd., particle size ≥1.5 mm, water content 50-55%), place it in a 50 L plastic bucket, and add 5-6 kg of deionized water;

[0051] 2) 1.15 kg of nickel nitrate hexahydrate (Ni 2+ and a strong acidic cation exchange resin sulfonate ion molar ratio of about 8:50), dissolved in 4 kg of deionized water;

[0052] 3) While stirring continuously, slowly pour the nickel nitrate solution into the strongly acidic cation exchange resin soaked in deionized water and react for 30 to 60 minutes;

[0053] 4) Draining the excess solution after the reaction is completed, washing the modified resin catalyst with water three times, and draining the water to complete the modification of the catalyst;

[0054] 5) The modified catalyst is loaded into the catalytic distillation column D4.

[0055] The hydration reactor R1 is loaded with 2 tons of strongly acidic cation exchange resin, and the catalytic distillation tower D4 is loaded with 0.2 tons of a special double bond isomerization catalyst. Fresh solvent is intermittently added through pipeline 18 or circulating solvent is intermittently discharged through pipeline 19 according to the required solvent ratio. The process operating conditions of the heavy removal tower D1, light removal tower D2, hydration reactor R1, C5 recovery tower D3, catalytic distillation tower D4, isopentene refining tower D5, azeotropic distillation tower D6, and tert-amyl alcohol refining tower D7 are shown in Table 2. The flow rates and compositions of each pipeline are shown in Tables 3, 4, and 5.

[0056] Table 2

[0057]

[0058] Note: The water-olefin ratio refers to the ratio of the amount of water to the amount of 2-methyl-1-butene in the feed, and the solvent ratio refers to the mass ratio of the solvent to the C5 (a mixture of 1-pentene and 2-methyl-1-butene) feed.

[0059] Table 3

[0060]

[0061]

[0062] Table 4

[0063]

[0064]

[0065] Table 5

[0066]

[0067] The total conversion rate of isopentene in the hydration reaction unit was 60.07%, the selectivity of tert-amyl alcohol was 99.81%, and the yield of 1-pentene was 98.09%.

[0068] Example 2

[0069] The separation of C5 from coal chemical industry was carried out according to the steps in Example 1, with only the conditions of the hydration reaction being changed. The molar ratio of water to 2-methyl-1-pentene in the hydration reactor feed was 3, the mass ratio of the solvent to the C5 feed was 2.5, the total conversion of isopentene was 48.25%, the selectivity of tert-amyl alcohol was 99.92%, and the yield of 1-pentene was 98.26%.

[0070] Comparative Example 1

[0071] The separation of coal chemical C5 was carried out according to the steps in Example 1. The catalytic distillation tower was filled with 0.2 tons of unmodified strong acidic cation exchange resin. The heavy component content in the bottom material of the catalytic distillation tower was 7.69%, and the polymerization reaction of isopentene was relatively serious.

[0072] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. A method for producing 1-pentene from C5 in coal chemical industry and co-producing isopentene and tert-amyl alcohol, characterized in that: The following steps are involved: S1: The coal chemical C5 fraction is subjected to a weight removal treatment to obtain a fraction rich in isopentane, 1-pentene and 2-methyl-1-butene at the top of the tower; S2: performing a light removal treatment on the top fraction obtained in step S1 to remove the C4 fraction, 3-methyl-1-butene, and most of the isopentane, and obtaining a mixture of 1-pentene and 2-methyl-1-butene in the bottom of the tower; S3: mixing the bottom material obtained in step S2 with water and a solvent and then feeding the mixture into a fixed bed loaded with a catalyst for hydration reaction, wherein the catalyst is a strongly acidic cation exchange resin; S4: distilling the hydration product obtained in step S3 to obtain a mixture of 1-pentene, 2-methyl-1-butene and 2-methyl-2-butene at the top of the tower, and obtaining tert-amyl alcohol, water and solvent at the bottom of the tower; S5: passing the overhead material obtained in step S4 through a catalytic distillation column loaded with a double bond isomerization catalyst, thereby obtaining 1-pentene at the top and a material rich in 2-methyl-2-butene in the bottom of the column, wherein the double bond isomerization catalyst is a strongly acidic cation exchange resin modified with a metal ion; S6: distilling the 2-methyl-2-butene-rich material obtained in step S5 to obtain 2-methyl-2-butene at the top of the tower and heavy components at the bottom of the tower; S7: performing azeotropic distillation on the bottom material obtained in step S4 to obtain a mixture of an entrainer, tert-amyl alcohol, and water at the top of the tower. After separation, the water in the lower layer is returned to step S3 for recycling, and the entrainer and tert-amyl alcohol in the upper layer are refluxed to obtain tert-amyl alcohol and solvent in the bottom of the tower; S8: The bottom material obtained in step S7 is distilled to obtain tert-amyl alcohol at the top of the tower and the solvent at the bottom of the tower, and the solvent is returned to step S3 for recycling.

2. The method according to claim 1, characterized in that The operating pressure of step S1 is 0-0.1 MPa, the tower top temperature is 42-45° C., the tower bottom temperature is 62-65° C., the reflux ratio is 20-30, and the cis- and trans-pentene contents at the tower top are controlled to be ≤0.05%, and the 2-methyl-1-butene content in the tower bottom is controlled to be ≤0.5%.

3. The method according to claim 1, characterized in that The operating pressure of step S2 is 0.15-0.2 MPa, the tower top temperature is 45-48° C., the tower bottom temperature is 65-70° C., the reflux ratio is 40-50, and the tower top 1-pentene content is controlled to be ≤0.5%, and the tower bottom 3-methyl-1-butene content is controlled to be ≤0.05%.

4. The method according to claim 1, wherein The solvent in step S3 is selected from one or more of phenol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, and ethylene glycol monobutyl ether, preferably ethylene glycol ethyl ether; The reaction pressure of step S3 is 1-1.5 MPa, and the weight hourly space velocity of C5 feed is 0.5-1 h -1 The reactor inlet temperature is 50-66°C, the reactor outlet temperature is 55-70°C, the mass ratio of solvent to C5 is 2-3, the molar ratio of water to 2-methyl-1-butene is 3-4, the total isopentene conversion rate is 45-65%, and the selectivity of tert-amyl alcohol is ≥99.5%.

5. The method according to claim 1, wherein The water and solvent in step S3 include fresh deionized water, the water returned from step S7 and the solvent returned from step S8.

6. The method according to claim 1, characterized in that The operating pressure of step S4 is 0.05-0.1 MPa, the tower top temperature is 53-55° C., the tower bottom temperature is 123-126° C., the reflux ratio is 3-5, and the tower five fraction in the tower bottom is controlled to be ≤0.05%.

7. The method according to claim 1, characterized in that The metal ions of the metal ion-modified strong acid cation exchange resin in step S5 are selected from one or more of iron ions, copper ions, zinc ions, and nickel ions, preferably nickel ions, Ni 2+ The molar ratio of the sulfonate ion to the strong acidic cation exchange resin is 5 to 10:50; the mass ratio of the amount of the metal ion modified strong acidic cation exchange resin to the feed amount of the tower is 1 to 3:10; The operating pressure of step S5 is 0.05-0.1 MPa, the tower top temperature is 45-48° C., the tower bottom temperature is 60-65° C., the reflux ratio is 8-15, the tower top isopentene content is controlled to be ≤0.5%, the 1-pentene content is controlled to be ≥98%, and the 1-pentene content in the tower bottom is controlled to be ≤0.1%.

8. The method according to claim 1, characterized in that The operating pressure of step S6 is 0.05-0.1 MPa, the tower top temperature is 48-52° C., the tower bottom temperature is 90-95° C., the reflux ratio is 1-2, and the tower top 2-methyl-2-butene content is controlled to be ≥99%, and the tower bottom 2-methyl-2-butene content is controlled to be ≤0.1%.

9. The method according to claim 1, characterized in that The entrainer in step S7 can be benzene, toluene, n-hexane and cyclohexane, preferably n-hexane or cyclohexane, with an operating pressure of 0-0.05 MPa, a tower top temperature of 65-70°C, a tower bottom temperature of 125-128°C, and a reflux ratio of 10-15.

10. The method according to claim 1, characterized in that The operating pressure of step S8 is 0-0.05 MPa, the tower top temperature is 105-108° C., the tower bottom temperature is 135-140° C., and the reflux ratio is 3-5.

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