阅读说明：本技术 一种用于从石脑油中分离环烷烃和芳烃的复合溶剂 (Composite solvent for separating cyclane and aromatic hydrocarbon from naphtha ) 是由 陈谦 李进龙 马克存 王辉 杨春基 王昕� 曾群英 张波 高萌 张永军 张爱萍 于 2019-11-14 设计创作，主要内容包括：一种适合从石脑油中分离环烷烃和芳烃的复合溶剂,由N,N-二甲基甲酰胺、环糊精和1-丁基-3-甲基咪唑二氰胺盐复配组成,复配比例为N,N-二甲基甲酰胺:环糊精:1-丁基-3-甲基咪唑二氰胺盐＝(80～90):(10～20):1。与环丁砜相比,该复配溶剂对环烷烃的选择性可达到3.2,环烷烃的脱除率可达62％以上；该复配溶剂对芳烃的选择性可达到37.2,芳烃的脱除率可达到95％以上。(A composite solvent suitable for separating cyclane and aromatic hydrocarbon from naphtha is prepared from N, N-dimethyl formamide, cyclodextrin and 1-butyl-3-methylimidazole dicyanamide salt through mixing (80-90): (10-20): 1). Compared with sulfolane, the compound solvent has the selectivity of 3.2 to the cycloparaffin, and the removal rate of the cycloparaffin can reach more than 62 percent; the selectivity of the compound solvent to aromatic hydrocarbon can reach 37.2, and the removal rate of the aromatic hydrocarbon can reach more than 95%.)

1. A composite solvent for separating naphthenes and aromatics from naphtha, comprising: comprises N, N-dimethylformamide, cyclodextrin and 1-butyl-3-methylimidazolium dicyanamide salt.

2. The composite solvent according to claim 1, characterized in that: the composition consists of the following components:

80-90 parts by weight of N, N-dimethylformamide;

10-20 parts by weight of cyclodextrin;

1 part by weight of 1-butyl-3-methylimidazolium dicyanamide salt.

3. A method for producing the composite solvent according to claim 1 or 2, which is characterized by comprising: weighing N, N-dimethylformamide, keeping the set temperature of a reaction kettle constant at a preset temperature, sequentially and slowly adding cyclodextrin and 1-butyl-3-methylimidazol dicyanamide salt under the stirring condition, and continuously stirring until the mixture is uniformly mixed after the addition is finished to obtain the composite solvent.

4. The method for preparing the composite solvent according to claim 3, wherein the predetermined temperature is 60 to 80 ℃.

5. A process for separating naphthenes and aromatics from naphtha, which is characterized by using the complex solvent described in claim 1 or 2, and is carried out on an extraction apparatus comprising:

one end of the static mixer M1 is respectively connected with an N, N-dimethylformamide storage tank, a cyclodextrin storage tank and a 1-butyl-3-methylimidazol dicyanamide storage tank, and the other end is respectively connected with the top of an extraction tower T1 and the bottom of a reduced pressure distillation tower T2; the bottom of the extraction tower T1 is connected with the inlet of a vacuum distillation tower T2;

the method for separating naphthenic hydrocarbon and aromatic hydrocarbon from naphtha comprises the following steps:

step (1): respectively leading N, N-dimethylformamide, cyclodextrin and 1-butyl-3-methylimidazolium dicyanamide salt out of respective storage tanks, and entering a static mixer M1; after fully mixing, introducing the mixture into a reduced pressure distillation tower T1 from the top of an extraction tower T1, carrying out countercurrent contact with naphtha entering from the bottom of T1, carrying out liquid-liquid extraction, and then, flowing out raffinate oil from the top of a reduced pressure distillation tower T1, and leading most of naphthenic hydrocarbon, aromatic hydrocarbon and all composite solvents out of the bottom of the reduced pressure distillation tower T1 to the reduced pressure distillation tower T2;

step (2): after the reduced pressure distillation, the composite solvent flows out from the bottom of the reduced pressure distillation tower T2 and is circulated to the top of the reduced pressure distillation tower T1, and after being mixed with fresh composite solvent, the composite solvent enters the reduced pressure distillation tower T1, and a naphthenic hydrocarbon and aromatic hydrocarbon mixture flows out from the top of the reduced pressure distillation tower T2.

6. The method for separating naphthenes and aromatics from naphtha according to claim 5, wherein the mass ratio of the composite solvent to the naphtha is 2-10: 1, preferably 2-6: 1.

7. The method for separating naphthenes and aromatics from naphtha as claimed in claim 5, wherein the operating temperature of the static mixer is constant at 60-80 ℃.

8. The method for separating naphthenes and aromatics from naphtha as claimed in claim 5, wherein the operating temperature of extraction column T1 is 30-120 ℃, preferably 50-80 ℃, and the operating pressure of extraction column T1 is 0.01-2.0 MPa, preferably 0.1-1.0 MPa.

9. The method for separating naphthenes and aromatics from naphtha as claimed in claim 5, wherein the operating temperature of vacuum distillation tower T2 is 20-100 ℃, preferably 20-50 ℃; the operating pressure of the reduced pressure distillation tower T2 is 0.01-0.08 MPa, preferably 0.02-0.06 MPa.

Technical Field

The invention relates to a composite solvent suitable for separating naphthenic hydrocarbon and aromatic hydrocarbon from naphtha.

Background

Naphtha is composed of normal paraffin, isoparaffin, naphthene and aromatic hydrocarbon, and is an important raw material for catalytic reforming and ethylene cracking. Among them, the yield of ethylene produced by cracking normal paraffin and isoparaffin is high, and it can not be converted into aromatic hydrocarbon in the reforming process, so that it is a relatively ideal ethylene cracking raw material. The cycloparaffins can obtain propylene and butadiene with higher yield after cracking, and can be easily converted into aromatic hydrocarbons under reforming conditions, so the cycloparaffins are suitable for raw materials of ethylene cracking and catalytic reforming. The aromatic hydrocarbon does not contribute to the yield of ethylene and the like during cracking, is easy to coke, and shortens the production period of the device. Thus, aromatics are not suitable as ethylene cracking feedstocks.

As crude oil becomes heavier, naphtha yields decrease, and the market demand for olefins and aromatics continues to increase, the problem of catalytic reforming and ethylene cracking unit feedstock configurations becomes more pronounced. At present, the naphtha is separated mainly by a light-heavy cutting mode in industry, and the method has the defects that the naphtha cannot be effectively separated according to components, so that the condition that aromatic hydrocarbon is suitable and alkene is suitable is obtained, and the raw materials cannot be fully used. In addition, in the prior art, methods such as adsorption separation and extraction separation of naphtha have been studied, but they are mainly used for separating normal paraffins from naphtha.

CN1476474A discloses a method for selectively separating normal paraffin from naphtha by adsorption separation, and CN1710030A discloses a method for obtaining desorbed oil rich in normal paraffin from naphtha by using molecular sieve as adsorbent. CN1292050C discloses a method for separating aromatic hydrocarbon and normal alkane from naphtha by a two-step method.

CN1277907C discloses a naphtha extraction separation method. The sulfolane is used as an extracting agent, and alkane and arene are obtained by separating naphtha under the conditions that the agent-oil ratio is 5-11: 1, the temperature is 95-128 ℃ and the pressure is 0.6-1.0 MPa.

Although the ethylene cracking raw material rich in n-alkane can be obtained by the technology, the ethylene yield is improved, but the n-alkane or the aromatic hydrocarbon is mainly separated from the naphtha, and the cycloparaffin and the aromatic hydrocarbon cannot be flexibly separated at the same time, so the cycloparaffin in the naphtha is not well utilized.

Disclosure of Invention

The invention aims to provide a composite solvent suitable for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha, which can enhance the separation effect of the naphthenes and the aromatic hydrocarbons from the naphtha, effectively separate the aromatic hydrocarbons contained in the naphtha by adjusting the compounding ratio of components, and adapt to the requirements of different ethylene cracking devices on the performance of naphtha raw materials by flexibly adjusting the proportion of the naphthenes in the naphtha.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the invention provides a composite solvent for separating naphthenic hydrocarbon and aromatic hydrocarbon from naphtha, which consists of N, N-dimethylformamide, cyclodextrin and 1-butyl-3-methylimidazolium dicyanamide salt.

The composite solvent provided by the invention is preferably as follows: the composition comprises the following components in parts by weight:

80-90 parts by weight of N, N-dimethylformamide;

10-20 parts by weight of cyclodextrin;

1 part by weight of 1-butyl-3-methylimidazolium dicyanamide salt.

The invention provides a preparation method of a composite solvent, which is the preparation method of the composite solvent and specifically comprises the following steps: weighing N, N-dimethylformamide, keeping the set temperature of a reaction kettle constant at a preset temperature, sequentially and slowly adding cyclodextrin and 1-butyl-3-methylimidazol dicyanamide salt under the stirring condition, and continuously stirring until the mixture is uniformly mixed after the addition is finished to obtain the composite solvent.

The preparation method of the composite solvent provided by the invention is preferably as follows: the preset temperature is 60-80 ℃.

Finally, the invention provides a process for separating naphthenes and aromatics from naphtha, using the above-mentioned complex solvent, carried out on an extraction plant comprising:

one end of the static mixer M1 is connected with an N, N-dimethylformamide, cyclodextrin and 1-butyl-3-methylimidazol dicyanamide storage tank, and the other end is respectively connected with the top of an extraction tower T1 and the bottom of a reduced pressure distillation tower T2; the bottom of the extraction tower T1 is connected with the inlet of a vacuum distillation tower T2;

the method for separating naphthenic hydrocarbon and aromatic hydrocarbon from naphtha comprises the following steps:

step (1): respectively leading N, N-dimethylformamide, cyclodextrin and 1-butyl-3-methylimidazolium dicyanamide salt out of respective storage tanks, and entering a static mixer M1; after fully mixing, introducing the mixture into a reduced pressure distillation tower T1 from the top of an extraction tower T1, carrying out countercurrent contact with naphtha entering from the bottom of T1, carrying out liquid-liquid extraction, and then, flowing out raffinate oil from the top of a reduced pressure distillation tower T1, and leading most of naphthenic hydrocarbon, aromatic hydrocarbon and all composite solvents out of the bottom of the reduced pressure distillation tower T1 to the reduced pressure distillation tower T2;

step (2): after the reduced pressure distillation, the composite solvent flows out from the bottom of the reduced pressure distillation tower T2 and is circulated to the top of the reduced pressure distillation tower T1, and after being mixed with fresh composite solvent, the composite solvent enters the reduced pressure distillation tower T1, and a naphthenic hydrocarbon and aromatic hydrocarbon mixture flows out from the top of the reduced pressure distillation tower T2.

The present invention provides a process for separating naphthenes and aromatics from naphtha, wherein it is preferred that: the mass ratio of the composite solvent to the naphtha is 2-10: 1, preferably 2-6: 1.

The present invention provides a process for separating naphthenes and aromatics from naphtha, wherein it is preferred that: the operating temperature of the static mixer is constant at 60-80 ℃.

The present invention provides a process for separating naphthenes and aromatics from naphtha, wherein it is preferred that: the operating temperature of the extraction tower T1 is 30-120 ℃, preferably 50-80 ℃, and the operating pressure of the extraction tower T1 is 0.01-2.0 MPa, preferably 0.1-1.0 MPa.

The present invention provides a process for separating naphthenes and aromatics from naphtha, wherein it is preferred that: the operating temperature of the reduced pressure distillation tower T2 is 20-100 ℃, and preferably 20-50 ℃; the operating pressure of the reduced pressure distillation tower T2 is 0.01-0.08 MPa, preferably 0.02-0.06 MPa.

According to some embodiments of the invention, the invention may be further stated as follows:

a composite solvent suitable for separating cyclane and arene from naphtha and the main steps and method for compounding the same are detailed as follows:

1. the aromatic hydrocarbon is separated from the naphtha by taking N, N-dimethylformamide (I) as a main solvent.

2. The cyclodextrin (II) is added into the N, N-dimethylformamide (I) in a proper proportion to form a composite solvent, so that the effect of simultaneously separating aromatic hydrocarbon and naphthenic hydrocarbon from naphtha is further improved, and the selectivity of separating the naphthenic hydrocarbon is improved.

3. Adding ionic liquid 1-butyl-3-methylimidazolium dicyanamide salt (III) into a composite solvent consisting of N, N-dimethylformamide (I) and cyclodextrin (II), so that the composite solvent has the function of flexibly adjusting the proportion of naphthene in naphtha.

4, compounding of a solvent: firstly, weighing a certain amount of N, N-dimethylformamide (I), keeping the temperature constant within the range of 60-80 ℃, slowly adding cyclodextrin (II) and 1-butyl-3-methylimidazolium dicyanamide salt (III) according to a certain proportion in the stirring process, and continuing stirring until the solvent is uniformly mixed after the addition is finished.

According to the characteristics of the raw materials of naphtha, the preparation temperature is constant within the range of 60-80 ℃.

According to the characteristics of the raw materials of naphtha, the mixing ratio of N, N-dimethylformamide (I), cyclodextrin (II) and 1-butyl-3-methylimidazol dicyanamide salt (III) is I: II: III (80-90) to (10-20) to 1 (mass).

The composite solvent can be used for extracting naphtha at the temperature range of 30-80 ℃ and the pressure range of 0.01-2.0 MPa so as to separate aromatic hydrocarbon and separate part or all of naphthene as required.

The extraction performance of the composite solvent refers to the solubility of the composite solvent to naphthenic hydrocarbon and aromatic hydrocarbon in naphtha under the condition of a certain solvent-oil ratio, and is characterized by using selectivity and removal rate parameters.

The selectivity was calculated using the formula:

in which S represents selectivity, C_i ^{Extracted oil}Denotes the concentration of component i in the extract oil, C_i ^{Raffinate oil}Indicates the concentration of component i in the raffinate oil.

The removal rate was calculated using the following formula:

in which P% represents selectivity, C_i ^{Extracted oil}Denotes the concentration of component i in the extract oil, C_i ^{Raw oil}The concentration of the i component in the feed oil is shown, and beta represents the yield of raffinate oil.

The selectivity and the removal rate of the composite solvent to the naphthenic hydrocarbon in naphtha can reach 3.2 and 62 percent respectively.

The selectivity and the removal rate of the composite solvent to the aromatic hydrocarbon in the naphtha can reach 37.0 percent and 95 percent.

The composite solvent has the characteristic of adjustability, namely the extraction performance of the naphthenic hydrocarbon and the aromatic hydrocarbon in naphtha can be adjusted through the preparation proportion of the components.

The composite solvent provided by the invention is used for extracting and separating naphthenes and aromatics in naphtha, and the flow chart is shown in figure 1. Respectively leading N, N-dimethylformamide (I), cyclodextrin (II) and ionic liquid 1-butyl-3-methylimidazolium dicyanamide salt (III) out of respective storage tanks, entering a static mixer M1, fully mixing, leading into an extraction tower T1 from the top of the tower, and carrying out countercurrent contact with naphtha entering from the bottom of the T1; after liquid-liquid extraction, the top stream of T1 is naphtha (raffinate oil) with a part of naphthenic hydrocarbon and aromatic hydrocarbon removed, and most of the naphthenic hydrocarbon and aromatic hydrocarbon and all the composite solvents are led out from the bottom of T1 to a vacuum distillation tower T2; after reduced pressure distillation, the composite solvent flows out from the bottom of the T2 tower and circulates to the top of the T1 tower, the composite solvent and the fresh composite solvent are mixed and then enter a T1 tower, and the material flow at the top of the T2 tower is a naphthenic hydrocarbon and aromatic hydrocarbon mixture (extract oil) which can be used as a catalytic reforming raw material or other purposes.

In the method, the ratio of N, N-dimethylformamide (I), cyclodextrin (II) and ionic liquid 1-butyl-3-methylimidazolium dicyanamide salt (III) in the composite solvent is I: II: III (80-90): 10-20: 1 (mass).

In the method, the mass ratio of the composite solvent to the naphtha is (2-10): 1, preferably (2-6): 1.

In the method, the operation temperature of the static mixer is kept at 60-80 ℃.

In the method, the operation temperature of the extraction tower T1 is 40-120 ℃, and preferably 50-80 ℃.

In the above method, the operating pressure of the extraction column T1 is 0.01 to 2.0MPa, preferably 0.1 to 1.0 MPa.

In the above method, the operating temperature of the vacuum distillation tower T2 is 20 to 100 ℃, preferably 20 to 50 ℃.

In the above method, the operating pressure of the vacuum distillation column T2 is 0.01 to 0.08MPa, preferably 0.02 to 0.06 MPa.

The pressures are absolute pressures.

Drawings

Fig. 1 is a schematic diagram of the most basic flow of an extraction apparatus, in which valves, pumps, reboilers, condensers, etc. are not involved, but are well known to those skilled in the art.

Detailed Description

The invention provides a composite solvent for separating cyclane and arene from naphtha and a preparation and use method thereof.

Example 1

The preparation method comprises the steps of compounding N, N-dimethylformamide (I), cyclodextrin (II) and 1-butyl-3-methylimidazolium dicyanamide salt (III) to prepare a compound solvent, wherein the compounding ratio of I to II to III is 80 to 20 to 1, extracting and separating naphtha fraction according to the flow of a picture 1, the composition of used naphtha is shown in a table 1, the extraction operation parameters, the used solvent and the like are shown in a table 2, and the composition of raffinate oil and extract oil is shown in a table 3.

Example 2

This embodiment is substantially the same as embodiment 1, and is characterized in that:

the agent-oil ratio is increased from 2:1 to 3:1, and the operating temperature of the distillation tower is 50 ℃. The composition of naphtha used in the distillation column is shown in Table 1, the parameters of extraction operation, the solvent used, etc. are shown in Table 2, and the composition of raffinate oil and raffinate oil is shown in Table 3.

Example 3

This embodiment is substantially the same as embodiment 2, and is characterized in that:

the compound solvent is prepared by compounding N, N-dimethylformamide (I), cyclodextrin (II) and 1-butyl-3-methylimidazol dicyanamide salt (III), wherein the compounding ratio of I to II to III is 90 to 10 to 1, and the operating temperature of an extraction tower is 90 ℃. The composition of the used naphtha is shown in Table 1, the extraction parameters, the used solvents and the like are shown in Table 2, and the composition of the raffinate oil and the raffinate oil is shown in Table 3.

Example 4

This embodiment is substantially the same as embodiment 2, and is characterized in that:

the N, N-dimethylformamide (I), cyclodextrin (II) and 1-butyl-3-methylimidazol dicyanamide salt (III) are compounded to prepare a compound solvent, wherein the compounding ratio of I to II to III is 80 to 20 to 1 (mass). The composition of the used naphtha is shown in Table 1, the extraction parameters, the used solvents and the like are shown in Table 2, and the composition of the raffinate oil and the raffinate oil is shown in Table 3.

Comparative example 1

This embodiment is substantially the same as embodiment 2, and is characterized in that: the solvent is a mixture of N, N-dimethylformamide (I) and cyclodextrin (II), I: II ═ 80: 20. The composition of the used naphtha is shown in Table 1, the extraction parameters, the used solvents and the like are shown in Table 2, and the composition of the raffinate oil and the raffinate oil is shown in Table 3.

TABLE 1 naphtha composition

Item	Alkane hydrocarbons	Cycloalkanes	Olefins	Aromatic hydrocarbons
					PIONA value, mass%	54.4	32.8	0.10	12.7

TABLE 2 extraction Process conditions

TABLE 3 extraction results

Table 6 property data of two different distillates

Table 7 comparative series evaluation of series catalyst 1 and series catalyst 2 blend product properties