阅读说明：本技术 分离费托合成水相副产物中丙醇的方法 (Method for separating propanol from aqueous phase byproduct of Fischer-Tropsch synthesis ) 是由 金政伟 汤志刚 刘素丽 郭栋 石博文 贲国勋 张安贵 杨自玲 朱楠 陈久洲 于 2020-12-25 设计创作，主要内容包括：本发明涉及丙醇的分离技术领域,具体涉及一种分离费托合成水相副产物中丙醇的方法,所述方法包括：(1)在萃取剂存在下,对费托合成水相副产物进行萃取精馏,得到粗乙醇和混合馏分；(2)将混合馏分进行再生精馏,得到粗丙醇-I和萃取剂溶液；(3)将粗丙醇-I在80-115℃下进行脱丙精馏,得到粗丙醇-II和丙前杂质；(4)将粗丙醇-II在95-120℃下进行去重精馏,得到精制丙醇。本发明通过萃取精馏,破坏了水、乙醇、丙醇以及其他杂质形成的共沸,从而使乙醇从丙醇分离出来；通过设置脱丙精馏,利用水与丙醇和部分杂质形成的共沸,从丙醇中有效脱除了轻组分；再通过去重精馏,实现了丙醇与重组分的分离,得到了纯度大于98.5％的精制丙醇。(The invention relates to the technical field of propanol separation, in particular to a method for separating propanol from a Fischer-Tropsch synthesis water phase byproduct, which comprises the following steps: (1) in the presence of an extracting agent, carrying out extraction and rectification on the Fischer-Tropsch synthesis water phase by-product to obtain crude ethanol and mixed fraction; (2) carrying out regenerative rectification on the mixed fraction to obtain crude propanol-I and an extractant solution; (3) performing depropanization rectification on the crude propanol-I at the temperature of 80-115 ℃ to obtain crude propanol-II and pre-propanal impurities; (4) and (3) carrying out de-weighting rectification on the crude propanol-II at the temperature of 95-120 ℃ to obtain refined propanol. The invention destroys the azeotropy formed by water, ethanol, propanol and other impurities by extractive distillation, thereby separating the ethanol from the propanol; by the adoption of depropanization rectification, light components are effectively removed from the propanol by utilizing the azeotropy formed by water, the propanol and part of impurities; and then carrying out heavy rectification to realize the separation of the propanol and heavy components and obtain the refined propanol with the purity of more than 98.5 percent.)

1. A method for separating propanol from aqueous phase by-products of Fischer-Tropsch synthesis, comprising:

(1) in the presence of an extracting agent, carrying out extraction and rectification on the Fischer-Tropsch synthesis water phase by-product to obtain crude ethanol and mixed fraction;

(2) carrying out regenerative rectification on the mixed fraction to obtain crude propanol-I and an extractant solution;

(3) performing depropanization rectification on the crude propanol-I at the temperature of 80-115 ℃ to obtain crude propanol-II and pre-propanal impurities;

(4) and (3) carrying out de-weighting rectification on the crude propanol-II at the temperature of 95-120 ℃ to obtain refined propanol.

2. The method as claimed in claim 1, wherein, in the step (1), the condition of the extractive distillation at least satisfies: the temperature at the top of the tower is 75-85 ℃, and the temperature at the bottom of the tower is 145-165 ℃;

preferably, the conditions of the extractive distillation meet the following conditions: the ratio of the extraction and rectification solvents is 1.5-4.5: 1.

3. The method according to claim 1 or 2, wherein in step (2), the conditions of the regenerative rectification at least satisfy: the temperature at the top of the tower is 68-78 ℃, and the temperature at the bottom of the tower is 135-165 ℃.

4. The method according to any one of claims 1 to 3, wherein in step (3), the depropanizing rectification conditions are at least satisfied: the temperature at the top of the tower is 80-90 ℃, and the temperature at the bottom of the tower is 100-115 ℃;

preferably, the depropanization rectification conditions are as follows: the reflux ratio of the depropanization rectification is 4-7: 1.

5. The method according to any one of claims 1 to 4, wherein in step (4), the condition of the de-heavy distillation at least satisfies: the temperature at the top of the tower is 95-105 ℃, and the temperature at the bottom of the tower is 110-120 ℃.

6. The method according to any one of claims 1 to 5, wherein in step (4), preferably, the condition of the de-heavy distillation satisfies: the reflux ratio of the de-heavy rectification is 2-7: 1.

7. The process of any one of claims 1-6, wherein the extractant comprises an organic solvent, an ionic liquid, and an inorganic salt.

8. The method of claim 7, wherein the weight ratio of the organic solvent, ionic liquid, and inorganic salt is 60-90:5: 5-25.

9. The process according to claim 7 or 8, wherein the weight ratio of the organic solvent, ionic liquid and inorganic salt is 75-80:5: 15-20.

10. The process according to any one of claims 7 to 9, wherein the organic solvent is selected from ethylene glycol and/or N-methylpyrrolidone;

preferably, the ionic liquid is [ Bmim [ ]][NTf₂]And/or [ Omim][BF₄]；

Preferably, the inorganic salt is selected from potassium salts, preferably potassium acetate and/or potassium carbonate.

Technical Field

The invention relates to the technical field of propanol separation, in particular to a method for separating propanol from a Fischer-Tropsch synthesis water phase byproduct.

Background

Fischer-Tropsch synthesis is a core technology of coal indirect liquefaction, coal is gasified to obtain synthesis gas, the synthesis gas is subjected to Fischer-Tropsch synthesis to obtain hydrocarbon products, commonly adopted catalysts comprise an iron-based catalyst and a cobalt-based catalyst, and the obtained products mainly comprise gasoline, diesel oil, kerosene, wax and the like. The Fischer-Tropsch process adopting the iron-based catalyst can generate about 1.2t of synthetic water phase by-products when 1t of oil product is produced. After the synthetic water phase by-product is primarily dehydrated, the remaining mixed liquor is low-carbon mixed alcohol, namely the mixed liquor of methanol, ethanol, propanol and the like and water. The alcohols are separated from the water-containing raw material solution, particularly methanol, ethanol and propanol with larger content are sold as products, and the comprehensive benefit of the indirect liquefaction device can be effectively improved.

The recovery of methanol is relatively easy to purify, and the mixture of ethanol and propanol after the separation of methanol often contains a large amount of impurities such as water, methanol, isopropanol, isobutanol, butanol, 1, 2-dimethoxyethane, dioxan methyl isopropyl ketone, 2-pentanol, 3-pentanol, 1, 2-dimethoxypropane, 2-hexanone, 1, 2-diethoxyethane, hexanol, heptanol, etc. The direct rectification method is adopted, and because ethanol, propanol, water and other impurities are easy to form the lowest azeotrope, the purity and the yield of the recovered propanol are seriously influenced.

Various methods for separating propanol have been reported in the prior art, for example, research on the separation of azeotropic organic aqueous solution system by using inorganic salt (university of Tianjin, Master's academic thesis 2005) discloses that a mixture system containing water, ethanol, propanol, etc. is separated by using the salting-out effect of inorganic salt and adopting a liquid phase equilibrium separation mode, but during the use process, the inorganic salt is easy to be supersaturated and separated out, thereby blocking equipment and pipelines.

Research on design and mechanism of ionic liquid for extraction separation of azeotrope of lower alcohol (doctor's academic paper of Shandong university of science and technology 2018) discloses extraction separation of aqueous solution of lower alcohol by using ionic liquid, such as [ Dmin [ ]][NTf₂]、[Opy][NTf₂]、[Bmin][MeSO₄]、[Hmin][MeSO₄]、[Omin][MeSO₄]However, the extraction separation of low carbon alcohol systems has the problems of serious two-phase mutual solubility and complex subsequent treatment and purification.

In addition, the separation of ethanol and propanol from aqueous phase byproducts of Fischer-Tropsch synthesis (the Master thesis 2005 at Tianjin university) and the simulation and optimization of mixed alcohol separation and dehydration processes for aqueous phase byproducts of Fischer-Tropsch synthesis (Wangfeng, Wanghongxing, Yangjin cup, Zhoulihua, Guoxiating, computer applied chemistry 2015, V32(5):568 and 571) disclose that the ethanol and propanol are separated by ordinary rectification, but the influence of oxygen-containing impurities on the separation of the ethanol and the propanol is not considered, and meanwhile, azeotropic rectification dehydration is adopted, so that a large amount of entrainer is vaporized, and the energy consumption is high; in the steady state research of a four-element alcohol separation system of a dividing wall rectifying tower (Wangzagfeng, Shentao, Panrong, Shenbenxian, Linghao, Petroleum institute (petroleum processing) 2017, V33(1): 115-fold 123), the separation problem of the polyhydric alcohol mixture is researched by adopting a dividing wall rectifying tower, but the influence of water and other oxygen-containing impurities in the separation process is not considered.

Disclosure of Invention

The invention aims to solve the problems of complex purification steps, high energy consumption and low purity and yield of propanol in the prior art, and provides a method for separating propanol from a Fischer-Tropsch synthesis water phase byproduct.

The inventor of the invention finds that when the rectification method is used for separating the propanol in the aqueous phase byproduct of the Fischer-Tropsch synthesis, the water and the oxygen-containing impurities (such as 1, 2-dimethoxyethane, dioxane, methyl isopropyl ketone and 1, 2-dimethoxypropane) are subjected to azeotropy, so that the water and the oxygen-containing impurities cannot be separated from the propanol, and the purity of the separated propanol is low.

In order to achieve the above object, the present invention provides a method for separating propanol from aqueous phase byproduct of fischer-tropsch synthesis, comprising:

(1) in the presence of an extracting agent, carrying out extraction and rectification on the Fischer-Tropsch synthesis water phase by-product to obtain crude ethanol and mixed fraction;

(2) carrying out regenerative rectification on the mixed fraction to obtain crude propanol-I and an extractant solution;

(3) performing depropanization rectification on the crude propanol-I at the temperature of 80-115 ℃ to obtain crude propanol-II and pre-propanal impurities;

(4) and (3) carrying out de-weighting rectification on the crude propanol-II at the temperature of 95-120 ℃ to obtain refined propanol.

By adopting the technical scheme, the invention destroys the azeotropy formed by water, ethanol, propanol and other impurities by the extraction rectification, and overcomes the interference of water on the separation of ethanol and propanol, thereby separating the ethanol from the propanol; by the adoption of depropanization rectification, light components are effectively removed from the propanol by utilizing the azeotropy formed by water, the propanol and part of impurities; and then carrying out heavy rectification to realize the separation of the propanol and heavy components and obtain the refined propanol with the purity of more than 98.5 percent.

Drawings

FIG. 1 is a flow diagram of a process for separating propanol from aqueous phase byproduct of Fischer-Tropsch synthesis according to one embodiment of the invention.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

As previously mentioned, the present invention provides a process for the separation of propanol from aqueous phase by-product of Fischer-Tropsch synthesis, which comprises:

(1) in the presence of an extracting agent, carrying out extraction and rectification on the Fischer-Tropsch synthesis water phase by-product to obtain crude ethanol and mixed fraction;

(2) carrying out regenerative rectification on the mixed fraction to obtain crude propanol-I and an extractant solution;

(3) performing depropanization rectification on the crude propanol-I at the temperature of 80-115 ℃ to obtain crude propanol-II and pre-propanal impurities;

(4) and (3) carrying out de-weighting rectification on the crude propanol-II at the temperature of 95-120 ℃ to obtain refined propanol.

In the invention, the azeotropy formed by water and ethanol, propanol and other impurities is destroyed by extractive distillation, in order to overcome the interference of water on ethanol separation and separate ethanol from Fischer-Tropsch synthesis water phase by-products, under the preferable conditions, in the step (1), the extractive distillation conditions at least meet the following requirements: the temperature at the top of the tower is 75-85 ℃, and the temperature at the bottom of the tower is 145-165 ℃; further preferably, the conditions of the extractive distillation satisfy: the extractive distillation solvent ratio is 1.5 to 4.5:1, and may be, for example, 1.5:1, 2:1, 3:1, 3.5:1, 4.5:1, or any value in the range defined by any two of the above values. The extraction and rectification solvent ratio refers to the weight ratio of the extracting agent to the aqueous phase byproduct of Fischer-Tropsch synthesis.

In the present invention, the extractant can be separated from the mixed fraction by regenerative distillation, preferably under the condition that in the step (2), the condition of the regenerative distillation at least satisfies: the temperature at the top of the tower is 68-78 ℃, and the temperature at the bottom of the tower is 135-165 ℃. In a preferred embodiment of the present invention, the extractant solution separated in step (2) is recycled to step (1) for addition to the extractant.

In the present invention, by depropanization rectification, light component impurities can be effectively removed from propanol by utilizing azeotropy of propanol and a part of impurities (such as water, methanol, isopropanol, isobutanol, 1, 2-dimethoxyethane, dioxane, methyl isopropyl ketone, 1, 2-dimethoxypropane and impurity components having boiling points between ethanol and propanol) and distilled from the top of a depropanization rectification column; preferably, in the step (3), the depropanization rectification condition at least satisfies the following conditions: the temperature at the top of the tower is 80-90 ℃, and the temperature at the bottom of the tower is 100-115 ℃; further preferably, the depropanization rectification conditions are as follows: the depropanization rectification reflux ratio is 4-7:1, and may be, for example, 4:1, 5:1, 5.5:1, 6:1, 7:1, or any value within a range defined by any two of the above values. The depropanization rectification reflux ratio is as follows: in the depropanization rectification process, the ratio of the reflux liquid flow L returning to the rectifying tower from the top of the rectifying tower to the product flow D at the top of the rectifying tower.

In the invention, the separation of propanol and heavy components is realized by the heavy component removal rectification, and the refined propanol with the purity of more than 98.5 percent is obtained; preferably, in the step (4), the condition of the de-heavy distillation at least satisfies the following condition: the temperature at the top of the tower is 95-105 ℃, and the temperature at the bottom of the tower is 110-120 ℃; further preferably, the condition of the de-heavy distillation satisfies: the depolymehzation reflux ratio is 2 to 7:1, and may be, for example, 2:1, 4:1, 5:1, 6:1, 7:1, or any value in the range defined by any two of the above values. The reflux ratio of the de-heavy distillation is as follows: in the process of the heavy component removal rectification, the ratio of the flow L of reflux liquid returned to the rectifying tower from the top of the rectifying tower to the flow D of a product at the top of the tower.

In the present invention, in order to further improve the separation efficiency and purity of propanol, it is preferable that the extractant comprises an organic solvent, an ionic liquid, and an inorganic salt. Further preferably, the weight ratio of the organic solvent, ionic liquid and inorganic salt is 60-90:5:5-25, preferably 75-80:5: 15-20.

According to the invention, the organic solvent is preferably selected from ethylene glycol and/or N-methylpyrrolidone; preferably, the ionic liquid is [ Bmim [ ]][NTf₂]And/or [ Omim][BF₄](ii) a Preferably, the inorganic salt is selected from potassium salts, preferably potassium acetate and/or potassium carbonate. Wherein Bmim and Omim respectively represent 1-butyl-3-methylimidazole cation and 1-methyl-3-octylimidazole cation, NTf₂Represents a trifluoromethylsulfonyl imide anion.

FIG. 1 is a flow chart of a method for separating propanol from aqueous phase byproduct of Fischer-Tropsch synthesis according to an embodiment of the present invention, and for better understanding of the method of the present invention, the present invention will now be described in detail with reference to FIG. 1. in a preferred embodiment of the present invention, as shown in FIG. 1, the method for separating propanol from aqueous phase byproduct of Fischer-Tropsch synthesis provided by the present invention comprises:

(1) in the presence of an extracting agent, introducing the Fischer-Tropsch synthesis aqueous phase byproduct into an extraction rectifying tower for extraction and rectification, obtaining crude ethanol at the top of the extraction rectifying tower, and obtaining mixed fraction in a tower kettle of the extraction rectifying tower;

(2) introducing the mixed fraction into a solvent regeneration tower for regeneration rectification to obtain crude propanol-I at the top of the solvent regeneration tower and an extractant solution in a tower kettle of the solvent regeneration tower, and introducing the extractant solution into the extraction rectification tower circularly to add the extractant;

(3) introducing the crude propanol-I into a pre-depropanization tower for depropanization rectification at the temperature of 80-115 ℃, obtaining crude propanol-II at the tower top of the pre-depropanization tower, and obtaining pre-propanization impurities (namely the light component impurities) in a tower kettle of the pre-depropanization tower;

(4) and introducing the crude propanol-II into a propanol refining tower to perform de-heavy rectification at the temperature of 95-120 ℃ to obtain refined propanol and heavy component impurities.

The present invention will be described in detail below by way of examples. In the following examples, extractant 1 was composed of ethylene glycol, [ Bmim ]][NTf₂]And potassium acetate according to the weight ratio of 80:5: 15;

the extractant 2 is composed of glycol, [ Omim][BF₄]And potassium acetate in a weight ratio of 75:5: 20;

the extractant 3 is composed of glycol, [ Omim][BF₄]And potassium carbonate in a weight ratio of 75:5: 20.

The composition of each stream was determined by gas chromatography.

Example 1

As shown in figure 1, the method for separating propanol from the aqueous phase byproduct of Fischer-Tropsch synthesis comprises the following steps:

(1) introducing a Fischer-Tropsch synthesis water phase by-product stream S1 into an extraction rectification tower in the presence of an extracting agent 1, wherein the reaction temperature is 78.6 ℃ at the top of the tower, 152.6 ℃ at the bottom of the tower, and the solvent ratio is 3: performing extractive distillation under 1 to obtain a crude ethanol material flow S2 at the top of the extractive distillation tower and a mixed fraction in a tower kettle of the extractive distillation tower;

(2) introducing the mixed fraction into a solvent regeneration tower, performing regenerative rectification at the tower top temperature of 71.8 ℃ and the tower bottom temperature of 147.4 ℃, obtaining crude propanol-I at the top of the solvent regeneration tower, obtaining an extractant solution in the tower bottom of the solvent regeneration tower, and circularly introducing the extractant solution into an extraction rectification tower to add the extractant;

(3) introducing the crude propanol-I into a pre-depropanization tower, wherein the tower top temperature is 85.3 ℃, the tower bottom temperature is 103.2 ℃, and the reflux ratio is 5: performing depropanization rectification under 1 to obtain a crude propanol-II material flow S3 at the top of a pre-depropanization tower and pre-propanization impurities in a tower kettle of the pre-depropanization tower;

(4) introducing the crude propanol-II into a propanol refining tower, wherein the temperature of the top of the tower is 98.3 ℃, the temperature of the bottom of the tower is 112.3 ℃, and the reflux ratio is 3: and (3) carrying out heavy component removal rectification at the temperature of 1 to obtain a refined propanol material flow S4 and heavy component impurities.

The process parameters for each step in this example are shown in table 1, and the weight composition of each stream is shown in table 2.

TABLE 1

TABLE 2

In Table 2, trace indicates that the content of the substance is a trace amount and is negligible. ppb being parts per billion by weight; ppm is parts per million by weight.

Example 2

The procedure of example 1 was followed except that extractant 2 was used as the extractant, the process parameters for each step are shown in Table 1, and the composition of each stream is shown in Table 3.

TABLE 3

In Table 3, trace indicates that the content of the substance is a trace amount and is negligible. ppb being parts per billion by weight; ppm is parts per million by weight.

Example 3

The procedure of example 1 was followed except that extractant 3 was used as the extractant, the process parameters for each step are shown in Table 1, and the composition of each stream is shown in Table 4.

TABLE 4

In Table 4, trace indicates that the content of the substance is a trace amount and is negligible. ppb being parts per billion by weight; ppm is parts per million by weight.

Example 4

The procedure of example 1 was followed except that ethylene glycol was used as the extractant.

As shown in figure 1, the method for separating propanol from the aqueous phase byproduct of Fischer-Tropsch synthesis comprises the following steps:

(1) introducing a Fischer-Tropsch synthesis water phase by-product stream S1 into an extraction rectification tower in the presence of an extracting agent 1, wherein the reaction temperature is 80.3 ℃ at the top of the tower, 148.2 ℃ at the bottom of the tower, and the solvent ratio is 3: performing extractive distillation under 1 to obtain a crude ethanol material flow S2 at the top of the extractive distillation tower and a mixed fraction in a tower kettle of the extractive distillation tower;

(2) introducing the mixed fraction into a solvent regeneration tower, performing regeneration rectification at the tower top temperature of 71.4 ℃ and the tower bottom temperature of 148.8 ℃, obtaining crude propanol-I at the top of the solvent regeneration tower, obtaining an extractant solution in the tower bottom of the solvent regeneration tower, and circularly introducing the extractant solution into an extraction rectification tower to add the extractant;

(3) introducing the crude propanol-I into a pre-depropanization tower, wherein the tower top temperature is 85.1 ℃, the tower bottom temperature is 102.7 ℃, and the reflux ratio is 5: performing depropanization rectification under 1 to obtain a crude propanol-II material flow S3 at the top of a pre-depropanization tower and pre-propanization impurities in a tower kettle of the pre-depropanization tower;

(4) introducing the crude propanol-II into a propanol refining tower, wherein the tower top temperature is 98.2 ℃, the tower bottom temperature is 113.2 ℃, and the reflux ratio is 3: and (3) carrying out heavy component removal rectification at the temperature of 1 to obtain a refined propanol material flow S4 and heavy component impurities.

The process parameters for each step in this example are shown in table 1, and the composition of each stream is shown in table 5.

TABLE 5

In Table 5, trace indicates that the content of the substance is a trace amount and is negligible. ppb being parts per billion by weight; ppm is parts per million by weight.

As can be seen from comparison of the data in tables 1,2 and 5, when only ethylene glycol is used as an extractant, the purity of ethanol in the top discharge S2 of the extractive distillation column is significantly reduced, and in addition, the extractive distillation solvent ratio and the de-emphasis distillation reflux ratio are also significantly increased, so that qualified refined propanol is obtained, but the energy consumption is significantly increased.

Comparative example 1

The process of example 1 was followed except that: the conditions for regenerative rectification are different.

As shown in figure 1, the method for separating propanol from the aqueous phase byproduct of Fischer-Tropsch synthesis comprises the following steps:

(1) introducing a Fischer-Tropsch synthesis water phase by-product stream S1 into an extraction rectification tower in the presence of an extracting agent 1, wherein the reaction temperature is 80.3 ℃ at the top of the tower, 148.2 ℃ at the bottom of the tower, and the solvent ratio is 3: performing extractive distillation under 1 to obtain a crude ethanol material flow S2 at the top of the extractive distillation tower and a mixed fraction in a tower kettle of the extractive distillation tower;

(2) introducing the mixed fraction into a solvent regeneration tower, performing regeneration rectification at the tower top temperature of 102.5 ℃ and the tower bottom temperature of 212.3 ℃, obtaining crude propanol-I at the top of the solvent regeneration tower, obtaining an extractant solution in the tower bottom of the solvent regeneration tower, and introducing the extractant solution into an extraction rectification tower in a circulating manner to add the extractant;

(3) introducing the crude propanol-I into a pre-depropanization tower, wherein the tower top temperature is 85.1 ℃, the tower bottom temperature is 102.7 ℃, and the reflux ratio is 5: performing depropanization rectification under 1 to obtain a crude propanol-II material flow S3 at the top of a pre-depropanization tower and pre-propanization impurities in a tower kettle of the pre-depropanization tower;

(4) introducing the crude propanol-II into a propanol refining tower, wherein the tower top temperature is 98.2 ℃, the tower bottom temperature is 113.2 ℃, and the reflux ratio is 3: and (3) carrying out heavy component removal rectification at the temperature of 1 to obtain a refined propanol material flow S4 and heavy component impurities.

The process parameters for each step in this example are shown in table 1, and the composition of each stream is shown in table 6.

TABLE 6

In Table 6, trace indicates that the content of the substance is a trace amount and is negligible. ppb being parts per billion by weight; ppm is parts per million by weight.

As can be seen by comparing the data of the examples 1-4 with the data of the comparative example 1, the method can effectively separate the ethanol and the propanol from the aqueous phase byproduct of the Fischer-Tropsch synthesis, the purity of the separated ethanol is higher than 95%, and the purity of the propanol reaches more than 98.5%.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of technical features in other suitable ways, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.