阅读说明：本技术 由煤基混合戊烯制备戊烷的方法及其应用 (Method for preparing pentane from coal-based mixed pentene and application thereof ) 是由 李志光 李民 毕远军 高艳 王宏 孙高攀 张俊 邱鹏利 于 2021-01-05 设计创作，主要内容包括：本发明涉及煤化工领域,公开了一种由煤基混合戊烯制备戊烷的方法及其应用,该方法包括以下步骤：1)将煤基混合戊烯和碳五溶剂混合后进行第一精馏得到碳五馏分并回收溶剂的步骤；2)将步骤1)所得碳五馏分进行第一加氢的步骤；3)将步骤2)所得加氢产物进行第二精馏的步骤；4)将步骤3)所得产物进行正异戊烷分离得到正戊烷和异戊烷的步骤。该方法工艺简单,收率高,能够制备得到高纯度的正戊烷和异戊烷,提高了煤基混合戊烯的经济利用价值。(The invention relates to the field of coal chemical industry, and discloses a method for preparing pentane from coal-based mixed pentene and an application thereof, wherein the method comprises the following steps: 1) mixing the coal-based mixed pentene and the carbon five solvent, then carrying out first rectification to obtain carbon five fraction, and recovering the solvent; 2) a step of carrying out first hydrogenation on the carbon five fraction obtained in the step 1); 3) a second rectification step of the hydrogenation product obtained in the step 2); 4) separating the product obtained in the step 3) into n-pentane and isopentane. The method has simple process and high yield, can prepare high-purity n-pentane and isopentane, and improves the economic utilization value of the coal-based mixed pentene.)

1. A method for preparing pentane from coal-based mixed pentene is characterized by comprising the following steps:

1) mixing the coal-based mixed pentene and the carbon five solvent, then carrying out first rectification to obtain carbon five fraction, and recovering the solvent;

2) a step of carrying out first hydrogenation on the carbon five fraction obtained in the step 1);

3) a second rectification step of the hydrogenation product obtained in the step 2);

4) separating the product obtained in the step 3) into n-pentane and isopentane.

2. The process as claimed in claim 1, wherein in step 1), the first rectification is carried out in a de-heavy column, the bottom temperature is 68-71 ℃, the top temperature is 29-31 ℃, the pressure in the column is 0.3-0.4Mpa, and the reflux ratio is 1.9-2.4.

3. The method according to claim 1, wherein in step 1), the method for recovering the solvent is as follows: passing the first rectified product through a solvent recovery column;

preferably, the bottom temperature of the solvent recovery tower is 33-36 ℃, the top temperature of the solvent recovery tower is 30-31 ℃, the pressure in the tower is 0.3-0.4Mpa, and the reflux ratio is 2.2-2.5;

preferably, the carbon five solvent is n-pentane and/or isopentane;

preferably, the mass ratio of the coal-based mixed pentene to the carbon five solvent is 1: 5-9.

4. The process of claim 1, wherein in step 2), the conditions of the first hydrogenation are: the hydrogenation temperature is 30-60 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 25-40.

5. The method of claim 1, wherein the method further comprises: in step 2), the first hydrogenation is followed by cooling and a second hydrogenation step.

Preferably, the cooling is such that the first hydrogenation product temperature is in the range of from 30 to 35 ℃.

6. The process of claim 5, wherein the second hydrogenation conditions are: the hydrogenation temperature is 30-45 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 10-20.

7. The process according to claim 1, wherein in step 1), the second rectification is carried out in a lightness-removing column, and the conditions of the second rectification comprise: reducing the pressure of the hydrogenation product to 0.05-0.1MPa at 25-30 ℃.

8. The process as claimed in claim 1, wherein in the step 1), the separation of n-isopentane is carried out in a separation column, the bottom temperature is 34-36 ℃, the top temperature is 28.5-30 ℃, the pressure in the column is 0.2-0.3Mpa, and the reflux ratio is 3.2-3.8.

9. The method of claim 1, wherein the method further comprises: refining the isopentane obtained in the step 4);

preferably, the refining is carried out in an isopentane rectifying tower, the bottom temperature is 31-33 ℃, the top temperature is 27-29 ℃, the pressure in the tower is 0.2-0.3Mpa, and the reflux ratio is 4.4-5.1.

10. Use of a process for the preparation of pentane as claimed in any one of claims 1 to 9 in the preparation of pentane.

Technical Field

The invention relates to the field of coal chemical industry, in particular to a method for preparing pentane from coal-based mixed pentene and application thereof.

Background

At present, the total yield of coal/methanol to olefin in China can reach 1460 ten thousand tons per year, and coal-based mixed pentene is one of main byproducts produced in the production process of methanol to olefin, and accounts for about 8 percent of the total yield of coal/methanol to olefin, so that the current capacity of coal-based mixed pentene in China is about 117 ten thousand tons per year, and the coal-based mixed pentene is one of main supply products of carbon five in China. The first one is blended into gasoline and diesel oil in the form of blend oil to be used as automobile fuel, and from the technical and economic aspects, the coal or methanol which can be directly used as fuel in the production process of preparing olefin from methanol is converted by a complex process and then is used as fuel again, so that the energy utilization rate is very low, and the method is an application method with high energy consumption, low pollution and low output. The other scheme is that the coal-based mixed pentene is cracked into low-carbon olefins such as ethylene, propylene and the like through a catalytic cracking process for secondary utilization. In the components of the coal-based mixed pentene, the content of 1-pentene and 2-pentene which can be cracked into ethylene and propylene products with high utilization value is about 40 percent (mass fraction), while in the catalytic cracking process of other coal-based mixed pentene components, the main cracking products are methane and naphthenic hydrocarbon products with low utilization value, and meanwhile, in the cracking process, a large amount of coal-based mixed pentene also forms catalyst carbon coke, so that the catalytic cracking economy of the coal-based mixed pentene is poor.

Disclosure of Invention

The invention aims to provide a method for preparing pentane from coal-based mixed pentene, which is simple in process and high in yield, and can be used for preparing high-purity n-pentane and isopentane and improving the economic utilization value of the coal-based mixed pentene.

In order to achieve the above objects, one aspect of the present invention provides a method for preparing pentane from coal-based mixed pentenes, the method comprising the steps of:

1) mixing the coal-based mixed pentene and the carbon five solvent, then carrying out first rectification to obtain carbon five fraction, and recovering the solvent;

2) a step of carrying out first hydrogenation on the carbon five fraction obtained in the step 1);

3) a second rectification step of the hydrogenation product obtained in the step 2);

4) separating the product obtained in the step 3) into n-pentane and isopentane.

Preferably, in the step 1), the first rectification is carried out in a de-heavy tower, the temperature of the bottom of the tower is 68-71 ℃, the temperature of the top of the tower is 29-31 ℃, the pressure in the tower is 0.3-0.4Mpa, and the reflux ratio is 1.9-2.4.

Preferably, in step 1), the method for recovering the solvent is as follows: passing the first rectified product through a solvent recovery column.

Preferably, the bottom temperature of the solvent recovery tower is 33-36 ℃, the top temperature of the solvent recovery tower is 30-31 ℃, the pressure in the tower is 0.3-0.4Mpa, and the reflux ratio is 2.2-2.5.

Preferably, the carbon five solvent is n-pentane and/or isopentane.

Preferably, the mass ratio of the coal-based mixed pentene to the carbon five solvent is 1: 5-9.

Preferably, in step 2), the conditions of the first hydrogenation are as follows: the hydrogenation temperature is 30-60 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 25-40.

Preferably, the method further comprises: in step 2), the first hydrogenation is followed by cooling and a second hydrogenation step.

Preferably, the cooling is such that the first hydrogenation product temperature is in the range of from 30 to 35 ℃.

Preferably, the conditions of the second hydrogenation are: the hydrogenation temperature is 30-45 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 10-20.

Preferably, in step 1), the second rectification is performed in the light ends removal column, and the conditions of the second rectification include: reducing the pressure of the hydrogenation product to 0.05-0.1MPa at 25-30 ℃.

Preferably, in the step 1), the separation of the n-isopentane is carried out in a separation tower, the temperature of the bottom of the tower is 34-36 ℃, the temperature of the top of the tower is 28.5-30 ℃, the pressure in the tower is 0.2-0.3Mpa, and the reflux ratio is 3.2-3.8.

Preferably, the method further comprises: refining the isopentane obtained in the step 4).

Preferably, the refining is carried out in an isopentane rectifying tower, the bottom temperature is 31-33 ℃, the top temperature is 27-29 ℃, the pressure in the tower is 0.2-0.3Mpa, and the reflux ratio is 4.4-5.1.

In a second aspect, the present invention provides the use of the process for the preparation of pentane according to the present invention in the preparation of pentane.

Through the technical scheme, the method for preparing pentane from coal-based mixed pentene is simple in process and high in yield, high-purity n-pentane and isopentane can be prepared, and the economic utilization value of the coal-based mixed pentene is improved.

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.

In the invention, the "coal-based mixed pentene" refers to a byproduct obtained by preparing olefin from coal/methanol, and meets the coal-based mixed pentene specified in GB/T37177-2018 standard.

In a first aspect, the present invention provides a process for preparing pentane from coal-based mixed pentenes, the process comprising the steps of:

1) mixing the coal-based mixed pentene and the carbon five solvent, then carrying out first rectification to obtain carbon five fraction, and recovering the solvent;

2) a step of carrying out first hydrogenation on the carbon five fraction obtained in the step 1);

3) a second rectification step of the hydrogenation product obtained in the step 2);

4) separating the product obtained in the step 3) into n-pentane and isopentane.

The inventors of the present invention have found that high purity n-pentane and isopentane products can be obtained by rectifying, hydrogenating in stages, and then rectifying and separating the coal-based mixed pentene, and that the yield is high, thereby completing the present invention.

According to the invention, before hydrogenation, rectification is carried out to remove the olefin with six or more carbon atoms in the coal-based mixed pentene, reduce the side reaction in the subsequent hydrogenation and save hydrogen, in order to ensure that the separation is more sufficient, preferably, the first rectification is carried out in a de-heavy tower, the temperature of the tower bottom is 68-71 ℃, the temperature of the tower top is 29-31 ℃, the pressure in the tower is 0.3-0.4Mpa, and the reflux ratio is 1.9-2.2; more preferably, the bottom temperature is 69-70 deg.C, the top temperature is 29.5-30.5 deg.C, the pressure in the column is 0.35-0.4MPa, and the reflux ratio is 2.0-2.1.

According to the invention, the carbon five solvent is used for separating the carbon five fraction and the fraction with the carbon number more than 5, and the carbon five solvent is recovered and recycled after separation. Preferably, the method for recovering the solvent is as follows: passing the first rectified product through a solvent recovery column; preferably, the bottom temperature of the solvent recovery tower is 33-36 ℃, the top temperature of the solvent recovery tower is 30-31 ℃, the pressure in the tower is 0.3-0.4Mpa, and the reflux ratio is 2.2-2.5; more preferably, the bottom temperature of the solvent recovery tower is 34-35 ℃, the top temperature of the solvent recovery tower is 30-31 ℃, the pressure in the tower is 0.35-0.4Mpa, and the reflux ratio is 2.3-2.4. When the conditions for solvent recovery are the above conditions, the solvent recovery is more sufficient.

In order to improve the rectification selectivity of the carbon five fraction, the carbon five solvent is preferably n-pentane and/or isopentane; preferably, the carbon five solvent is n-pentane.

In order to reduce the solvent loss and save the energy consumption while obtaining a good rectification effect, the mass ratio of the coal-based mixed pentene to the carbon five solvent is preferably 1: 50-100; more preferably, the mass ratio of the coal-based mixed pentene to the carbon five solvent is 1: 60-80.

According to the present invention, the hydrogenation is used for converting various pentenes in the carbon five cut into n-pentane and i-pentane, and from the viewpoint of making the hydrogenation sufficient and reducing side reactions while saving hydrogen, it is preferable that in step 2), the conditions of the first hydrogenation are: the hydrogenation temperature is 30-35 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of hydrogen to the five-carbon fraction is 1: 25-40; more preferably, the conditions of the first hydrogenation are: the hydrogenation temperature is 31-33 ℃, the hydrogenation pressure is 0.3-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 33-37.

According to the present invention, preferably, the method further comprises: in step 2), the first hydrogenation is followed by cooling and a second hydrogenation step.

The inventors of the present invention have found that cooling the carbon five fraction after the first hydrogenation and then performing the second hydrogenation can significantly reduce side reactions in the hydrogenation and also extend the life of the hydrogenation catalyst.

From the viewpoint of allowing side reactions to be reduced and the hydrogenation reaction to proceed rapidly and sufficiently, it is preferable that the cooling makes the first hydrogenation product at a temperature of 50 to 65 ℃; more preferably, the cooling is such that the first hydrogenation product temperature is in the range of 55 to 59 ℃.

Preferably, the conditions of the second hydrogenation are: the hydrogenation temperature is 30-45 ℃, the hydrogenation pressure is 0.2-0.4Mpa, and the mass ratio of the hydrogen to the five-carbon fraction is 1: 10-25.

According to the invention, the second rectification is used for separating pentane and components with a carbon number lower than 5, and in order to make the separation more complete, the second rectification is preferably carried out in a light ends removal column, and the conditions of the second rectification comprise: reducing the pressure of the hydrogenation product to 0.05-0.1Mpa at 25-30 ℃; more preferably, the conditions of the second rectification include: reducing the pressure of the hydrogenation product to 0.05-0.07Mpa at 28-29 ℃.

According to the invention, in order to fully separate the n-pentane and the isopentane, preferably, the n-isopentane separation is carried out in a separation tower, the bottom temperature of the separation tower is 34-36 ℃, the top temperature of the separation tower is 28.5-30 ℃, the pressure in the separation tower is 0.2-0.3Mpa, and the reflux ratio is 3.2-3.8; more preferably, the bottom temperature is 34.5-36 deg.C, the top temperature is 29-30 deg.C, the pressure in the column is 0.25-0.3Mpa, and the reflux ratio is 3.4-3.6.

According to the present invention, in order to obtain isopentane with higher purity, preferably, the method further comprises: refining the isopentane obtained in the step 4); preferably, the refining is carried out in an isopentane rectifying tower, the temperature of the bottom of the tower is 31-33 ℃, the temperature of the top of the tower is 27-29 ℃, the pressure in the tower is 0.2-0.3Mpa, and the reflux ratio is 4.4-5.1; more preferably, the bottom temperature is 32-33 deg.C, the top temperature is 27-29 deg.C, the pressure in the column is 0.2-0.3MPa, and the reflux ratio is 4.7-4.9.

In a second aspect the present invention provides the use of the process of the invention in the preparation of pentane.

The method has simple process and high yield, can prepare high-purity n-pentane and isopentane from the coal-based mixed pentene with lower value, and improves the economic utilization value of the coal-based mixed pentene.

The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

In the following examples, coal-based mixed pentenes were provided by Shenhuabaotian coal chemical company and comprised of: 20 mass percent of n-pentene, 35 mass percent of isoamylene, 61 mass percent of total pentenes, 96 mass percent of carbon five or more and less than or equal to 5mg/kg of total sulfur.

Example 1

(1) Mixing coal-based mixed pentene and a solvent (n-pentane) according to a mass ratio of 1:6 mixing, introducing into a de-weighting tower for first rectification, wherein the tower bottom temperature is 69 ℃, the tower top temperature is 30 ℃, the tower internal pressure is 0.35Mpa, the reflux ratio is 2.0, collecting components with the carbon number more than 5 from the tower bottom, collecting a mixture of the five carbon fractions and the solvent from the top, introducing the mixture into a solvent recovery tower, the tower bottom temperature is 35 ℃, the tower top temperature is 31 ℃, the tower internal pressure is 0.35Mpa, the reflux ratio is 2.3, recovering the solvent from the tower bottom, and collecting the five carbon fractions from the tower top.

(2) And (2) introducing the carbon five fraction obtained in the step (1) into a hydrogenation reaction device for first hydrogenation (specifically, a fixed bed device provided with a hydrogenation catalyst, wherein the catalyst is a metal-nickel-containing catalyst, the mass ratio of hydrogen to the carbon five fraction is 1: 34, the reaction temperature is 40 ℃, the reaction time is 5min, and the reaction pressure is 0.3Mpa), introducing the first hydrogenation product into a circulating water type cooler, cooling to 30 ℃, and introducing the cooled product into a hydrogenation reactor for second hydrogenation (specifically, the fixed bed device provided with the hydrogenation catalyst, wherein the catalyst is the metal-nickel-containing catalyst, the mass ratio of hydrogen to the carbon five fraction is 1: 12, the reaction temperature is 40 ℃, the reaction time is 2min, and the reaction pressure is 0.3 Mpa).

(3) And (3) introducing the second hydrogenation product obtained in the step (2) into a light component removal tower for second rectification, wherein the tower bottom temperature is 27 ℃, the tower top temperature is 29 ℃, and the tower internal pressure is 0.06MPa, so as to obtain light components from the tower top, and collecting the light component removal product from the tower bottom.

(4) And (4) introducing the light product removed in the step (3) into a separation tower for separation, wherein the tower bottom temperature is 35 ℃, the tower top temperature is 30 ℃, the tower internal pressure is 0.28Mpa, the reflux ratio is 3.5, n-pentane is obtained from the tower bottom, and isopentane is obtained from the side line of the tower top.

(5) And (4) introducing the isopentane obtained in the step (4) into a refining tower, wherein the tower bottom temperature is 32 ℃, the tower top temperature is 27 ℃, the tower internal pressure is 0.3Mpa, the reflux ratio is 4.8, and the isopentane is obtained from the side line of the tower top.

Examples 2 to 5

Pentane was prepared in the same manner as in example 1, except that the mass ratio of the coal-based mixed pentene and the solvent in the step (1) and the mass ratios of hydrogen to the carbon five fraction in the first hydrogenation and the second hydrogenation were the values shown in table 1.

Example 6

Pentane was prepared as in example 1, except that in step (2), no cooling and no second hydrogenation were carried out.

Comparative example 1

Pentane was prepared according to the method of example 1, except that step (2) was performed first and then step (1).

TABLE 1

The purities and overall yields of n-pentane and isopentane obtained in the examples and comparative examples are shown in table 2.

Total yield (%) - (mass of n-pentane + mass of isopentane)/mass of coal-based mixed pentene used

TABLE 2

Example numbering	N-pentane purity (%)	Isopentane purity (%)	Overall yield (%)
				Example 1	90.38	96.22	66.41
Example 2	90.27	96.38	65.47
				Example 3	90.41	96.23	66.28
Example 4	89.87	96.41	66.47
				Example 5	91.21	96.27	66.19
Example 6	90.33	96.33	66.21
				Comparative example 1	89.77	93.37	65.13

As can be seen from the results in Table 2, the method of the present invention for preparing pentane from coal-based mixed pentene can obtain n-pentane and isopentane with high purity and high yield.

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 various technical features in any other suitable way, 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.