CN110724023A - Preparation method of 2-methylpentane, 3-methylpentane and n-hexane - Google Patents
Preparation method of 2-methylpentane, 3-methylpentane and n-hexane Download PDFInfo
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- CN110724023A CN110724023A CN201911081905.5A CN201911081905A CN110724023A CN 110724023 A CN110724023 A CN 110724023A CN 201911081905 A CN201911081905 A CN 201911081905A CN 110724023 A CN110724023 A CN 110724023A
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- methylpentane
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/06—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by azeotropic distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
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Abstract
The invention discloses a preparation method of 2-methylpentane, 3-methylpentane and n-hexane, which comprises the following steps: (1) preparing a feedstock comprising light naphtha; (2) pretreating light naphtha to remove benzene and sulfur to obtain an intermediate product A; (3) carrying out 2, 3-dimethylbutane removal treatment on the intermediate product A to obtain an intermediate product B; (4) and mixing the intermediate product B with a first entrainer for azeotropic distillation to obtain 2-methylpentane and a mixed solution C, and separating the mixed solution C to obtain n-hexane and 3-methylpentane. The preparation method is simple, the raw materials are common and easy to obtain, the additional value of the raw materials can be improved, and a new raw material source and a new technology are provided for the production of 2-methylpentane, 3-methylpentane and n-hexane.
Description
Technical Field
The invention belongs to the field of chemical raw material preparation, and particularly relates to a production process of 2-methylpentane, 3-methylpentane and n-hexane.
Background
2-methylpentane, 3-methylpentane and n-hexane are important organic compounds, have wide application range and can be used as a solvent, a reagent and an organic synthesis intermediate.
Currently, 2-methylpentane is mainly prepared by Aldol polymerization, in which acetone is first converted to methyl isobutyl ketone (MIBK) and then converted to 2-Methylpentane (MP) by catalytic hydrodeoxygenation. However, the research on synthesizing MP by MIBK catalytic hydrodeoxygenation is quite rare, because the process involves complex processes of hydrogenation and dehydration to prepare olefin, further hydrogenation of olefin to alkane and the like, and the requirement on the catalyst is severe. At present, the method still stays in the laboratory research stage, and no large-scale industrial production is reported. The research on the production process of 3-methyl pentane is less, the 3-methyl pentane is mainly prepared from methyl cyclopentane or n-hexane in laboratories or chemical reagent companies, and the method has the advantages of low yield, small preparation amount and high price. At present, raffinate oil (containing 11% -13% of n-hexane) of a platinum reforming device is used as a raw material and is obtained after separation and purification, but the method is complicated to operate, multiple in used equipment and low in purity of the n-hexane obtained through production.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects and shortcomings in the background art and provide a preparation method of 2-methylpentane, 3-methylpentane and n-hexane.
A preparation method of 2-methylpentane, 3-methylpentane and n-hexane comprises the following steps:
(1) preparing a feedstock comprising light naphtha;
(2) pretreating light naphtha to remove benzene and sulfur to obtain an intermediate product A;
(3) carrying out 2, 3-dimethylbutane removal treatment on the intermediate product A to obtain an intermediate product B;
(4) and mixing the intermediate product B with a first entrainer for azeotropic distillation to obtain 2-methylpentane and a mixed solution C, and separating the mixed solution C to obtain n-hexane and 3-methylpentane.
The design idea of the technical scheme is that benzene, sulfur and 2, 3-dimethylbutane in naphtha are removed and then subjected to azeotropic distillation with an entrainer, and then separation treatment is carried out, so that relatively pure 2-methylpentane, 3-methylpentane and n-hexane can be obtained.
In the above aspect, the first entrainer is preferably water. The design idea is that the azeotropic point of water and 2-methyl pentane is lower than the azeotropic points of water and 3-methyl pentane and water and n-hexane, so that the difference of the boiling points among all the substances is enlarged, the water is selected as the first entrainer, the 2-methyl pentane can be well separated and purified, other organic entrainers are prevented from being introduced into a system, the subsequent separation and purification are facilitated, and the impurities in the product are reduced.
Preferably, in the above-described aspect, the separation treatment in the step (4) is performed by adsorbing the mixed solution with a molecular sieve. The idea here is that n-hexane has a boiling point of 68.7 deg.C, which is very close to the boiling point of the other components in intermediate B, and is difficult to separate by other methods. While molecular sieves have uniform micropores that are capable of adsorbing molecules smaller than their diameter to the interior of the pore cavities. The n-hexane has small molecular diameter and can be adsorbed to the inside of the pore cavity, and the 2-methylpentane and 3-methylpentane have large molecular diameter and cannot be adsorbed by a molecular sieve, so that the separation purpose can be achieved.
Preferably, in the above technical solution, the molecular sieve is a 5A molecular sieve. The idea of the design is that the 5A molecular sieve is used for adsorbing the n-hexane, so that the n-hexane removal efficiency and effect can be further improved.
Preferably, in the separation process in the step (4), the mixed solution C and the second entrainer are mixed and subjected to azeotropic distillation to obtain n-hexane and a mixed solution D, and the mixed solution D is adsorbed by using a 5A molecular sieve. The idea of the design is that the azeotropic distillation treatment is added before the molecular sieve adsorption is carried out on the mixed liquid C, the mixed liquid C can be separated in advance by one step before the molecular sieve adsorption is carried out, the content of normal hexane entering the adsorption tower is reduced, the using amount of the molecular sieve is reduced, and the cost is saved.
In the above aspect, the second azeotropic agent is preferably water. The design idea is that the azeotropic point of water 3-methyl pentane is lower than that of water and normal hexane, so that the 3-methyl pentane can be well separated and purified by selecting water as the first entrainer, and other organic entrainers are prevented from being introduced into the system, so that subsequent separation and purification are facilitated, and impurities in the product are reduced.
Preferably, in the above technical solution, the pretreatment in the step (1) is to perform hydrogenation reaction on the light naphtha under catalysis of a catalyst. The idea of the design is that benzene in light naphtha can be converted into cyclohexane and sulfur can be converted into hydrogen sulfide which is easy to remove by using catalytic hydrogenation reaction, so that benzene and sulfur which are harmful to human bodies in naphtha are removed; the method is simple to operate, and can improve the conversion rate of benzene and sulfur to the maximum extent.
Preferably, in the above technical solution, the catalyst is supported skeletal nickel. The purpose of the design is to use supported framework nickel to catalyze the hydrogenation reaction, so that the efficiency of the hydrogenation reaction can be improved, the content of nickel in the catalyst is reduced, and the cost is saved.
Preferably, in the above technical solution, the preparation method of the supported skeleton nickel comprises: mixing pseudo-boehmite, nickel-aluminum alloy powder, sesbania powder and a peptizing agent and then forming to obtain the supported skeleton nickel.
Preferably, in the above-mentioned technical means, the 2, 3-dimethylbutane removal treatment in the step (3) is carried out by mixing the intermediate product a with a third azeotropic agent and then carrying out azeotropic distillation. The idea of the design is that the intermediate product A is treated by using an azeotropic distillation mode, the 2, 3-dimethylbutane can be removed more thoroughly by utilizing the characteristic that the azeotropic point of the 2, 3-dimethylbutane and the entrainer is different from the azeotropic point of other substances and the entrainer, the method is simple and convenient to operate, and the removal effect of the 2, 3-dimethylbutane is good.
In the above aspect, the third azeotropic agent is preferably water. The idea of the design is that the difference of boiling points between substances to be separated can be enlarged by using water as an azeotropic agent, the azeotropic point of the water and the 2, 3-dimethylbutane is the lowest and is lower than the azeotropic point of the water and other substances at about 55 ℃, so that the separation difficulty can be reduced, and the separation effect can be improved.
Compared with the prior art, the invention has the advantages that: the preparation method provided by the invention is simple in process and simple and convenient in flow, the prepared product is thoroughly separated and has high purity, the selected raw materials are common and easy to obtain, the additional value of naphtha is obviously improved, a new raw material source and a new technology are provided for the production of 2-methylpentane, 3-methylpentane and n-hexane, and great social benefits and economic benefits are achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of azeotropic distillation in step (4) of example 1 of the present invention.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1:
the preparation method of the grease leaching solvent comprises the following steps:
(1) preparing a feedstock comprising light naphtha;
(2) carrying out catalytic hydrogenation reaction on the light naphtha till the light naphtha is completely reacted to obtain an intermediate product A, wherein the benzene content in the intermediate product A is 0.01 percent, and the sulfur content is 0.4 ppm; the catalytic hydrogenation reaction process parameters are as follows: the temperature is 140 ℃, and the volume ratio of hydrogen to oil is 120: 1, the reaction pressure is 0.2MPa, the reaction space velocity is 2h < -1 >, and the used catalyst is supported skeleton nickel.
(3) And mixing the intermediate product A with water, adding the mixture into a first azeotropic distillation tower for azeotropic distillation, obtaining an azeotrope of the water and the 2, 3-dimethylbutane from the top of the first azeotropic distillation tower, and obtaining an intermediate product B from the bottom of the tower.
(4) Mixing the intermediate product B with water, adding the mixture into a second azeotropic distillation tower for azeotropic distillation, obtaining an azeotrope of water and 2-methylpentane from the tower top of the second azeotropic distillation tower, and separating the water and the 2-methylpentane after condensation; feeding the discharged material at the bottom of the tower into a third azeotropic distillation tower for azeotropic distillation, obtaining an azeotrope of water and 3-methylpentane from the top of the tower, and separating water after condensation to obtain 3-methylpentane, wherein the 3-methylpentane contains n-hexane with the volume fraction of less than 8%; n-hexane was obtained from the bottom of the column. Adsorbing the 3-methylpentane at normal pressure and 110 deg.C with 5A molecular sieve at airspeed of 0.33h-1, regeneration pressure of-90 kPag, and adsorbent capacity of 10kg/m3And 3-methylpentane with the purity of 99.9 percent is obtained after adsorption separation, the 5A molecular sieve is subjected to regeneration desorption by using a high-temperature water vapor displacement method to obtain a desorption product, and the desorption product is merged into normal hexane.
Wherein, the flow chart of the azeotropic distillation in the step (4) is shown in figure 1.
The purity of 2-methylpentane, 3-methylpentane and n-hexane obtained finally in this example was 82%, 99.9% and 99.5% respectively.
Example 2:
the preparation method of the grease leaching solvent comprises the following steps:
(1) preparing a feedstock comprising light naphtha;
(2) carrying out catalytic hydrogenation reaction on the light naphtha till the light naphtha is completely reacted to obtain an intermediate product A, wherein the benzene content in the intermediate product A is 0.01 percent, and the sulfur content is 0.35 ppm; the catalytic hydrogenation reaction process parameters are as follows: the temperature is 145 ℃, the volume ratio of hydrogen to oil is 100: 1, the reaction pressure is 0.2MPa, and the reaction space velocity is 2.5h-1The catalyst used is supported skeletal nickel.
(3) Adding the intermediate product A and water into a first azeotropic distillation tower for azeotropic distillation, obtaining an azeotrope of the water and the 2, 3-dimethylbutane from the top of the first azeotropic distillation tower, and obtaining an intermediate product B from the bottom of the tower;
(4) adding the intermediate product B into a second azeotropic distillation tower for azeotropic distillation, obtaining an azeotrope of water and 2-methylpentane from the tower top of the second-stage azeotropic distillation tower, and separating water after condensation to obtain 2-methylpentane; discharging from the bottom of the tower, feeding into a third azeotropic distillation tower, obtaining an azeotrope of water and 3-methylpentane from the top of the tower, and separating water after condensation to obtain 3-methylpentane, wherein the 3-methylpentane contains normal hexane with a volume fraction of 7.8%; n-hexane was obtained from the bottom of the column. Adsorbing the 3-methylpentane at 105 deg.C and normal pressure with 5A molecular sieve at an air speed of 0.35 hr-1The regeneration pressure is-85 kPag, and the adsorption capacity of the adsorbent is 10kg/m3Adsorbing and separating to obtain 3-methylpentane with purity of 99.9%; and (3) regenerating and desorbing the 5A molecular sieve by using a high-temperature water vapor displacement method to obtain a desorption product, and incorporating the desorption product into n-hexane.
The purity of 2-methylpentane, 3-methylpentane and n-hexane obtained finally in this example was 84%, 99.8% and 99.4% respectively.
Claims (10)
1. A preparation method of 2-methylpentane, 3-methylpentane and n-hexane is characterized by comprising the following steps:
(1) preparing a feedstock comprising light naphtha;
(2) pretreating light naphtha to remove benzene and sulfur to obtain an intermediate product A;
(3) carrying out 2, 3-dimethylbutane removal treatment on the intermediate product A to obtain an intermediate product B;
(4) and mixing the intermediate product B with a first entrainer for azeotropic distillation to obtain 2-methylpentane and a mixed solution C, and separating the mixed solution C to obtain n-hexane and 3-methylpentane.
2. The process of claim 1 wherein the first entrainer is water.
3. The method according to claim 1, wherein the separation treatment in the step (4) is adsorption of the mixed solution C using a molecular sieve.
4. The method of claim 3, wherein the molecular sieve is a 5A molecular sieve.
5. The method according to claim 1, wherein the separation treatment in the step (4) is a step of subjecting the mixture C and a second entrainer to azeotropic distillation to obtain n-hexane and a mixture D, and subjecting the mixture D to adsorption by using a molecular sieve.
6. The method according to claim 5, wherein the second azeotropic agent is water.
7. The method according to claim 1, wherein the pretreatment in the step (1) is to perform hydrogenation reaction on the light naphtha under the catalysis of a catalyst.
8. The method of claim 7, wherein the catalyst is supported skeletal nickel.
9. The method according to claims 1 to 8, wherein the 2, 3-dimethylbutane-removing step (3) comprises mixing intermediate product A with a third entrainer and then subjecting the mixture to azeotropic distillation.
10. The method according to claim 9, wherein the third entrainer is water.
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| CN201911081905.5A CN110724023A (en) | 2019-11-07 | 2019-11-07 | Preparation method of 2-methylpentane, 3-methylpentane and n-hexane |
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