CN114989866B - Method and device for realizing Fischer-Tropsch synthesis oil graded utilization by utilizing reaction separation process - Google Patents

Abstract

The invention belongs to the field of chemical engineering, and particularly relates to a method and a device for realizing graded utilization of Fischer-Tropsch synthesis oil by using a reaction separation process. By utilizing a reaction separation process, different fractions of Fischer-Tropsch synthetic oil are directly used as alkylating agents, and alpha-olefin and coking benzene in the Fischer-Tropsch synthetic oil fractions are alkylated under the action of a catalyst to produce alkylbenzene with different carbon chain lengths. Meanwhile, an environment-friendly solid acid catalysis process is adopted to replace a liquid acid process, so that the problems of equipment corrosion, environmental pollution and the like in the existing process can be solved, the fraction section of Fischer-Tropsch synthetic oil can be directly used as a raw material, the separation process of high-carbon alcohol is avoided, and the production cost is further reduced. The invention adopts a double-bed filling mode in the fixed bed reactor, the upper layer catalyst is used for removing oxygen-containing compounds in materials, and the lower layer catalyst adopts a hierarchical pore molecular sieve for alkylation reaction.

Description

Method and device for realizing Fischer-Tropsch synthesis oil graded utilization by utilizing reaction separation process

Technical Field

The invention belongs to the field of chemical engineering, and particularly relates to a method and a device for realizing graded utilization of Fischer-Tropsch synthesis oil by using a reaction separation process.

Background

Fischer-tropsch oils contain significant amounts of alpha olefins which are normally saturated by hydrogenation to improve the performance of the liquid phase product as fuel. The process not only wastes a great amount of alpha-olefin resources with high added value, but also consumes a great amount of energy and valuable hydrogen, thereby reducing the economy of the coal-to-liquid process. How to fully utilize the olefin resources to realize high-value and fine utilization of the olefin resources and how to avoid the alkane-olefin separation process with high energy consumption in the utilization process of the alpha-olefin is the key for improving the utilization value of the coal-to-liquid product. Alkylbenzene is a common high-added-value product in production and life, and belongs to a typical petrochemical product. According to the length of alkyl benzene chain, it can be used for different purposes. The current industrial production method of long-chain alkyl benzene mainly adopts a liquid acid alkylation process. The olefin is derived from petroleum-based raw oil, the raw oil needs to be subjected to a series of treatments such as hydrodesulfurization and deoxidation, molecular sieve dewaxing, normal isoparaffin separation, normal hydrocarbon dehydrogenation, diene selective hydrogenation and the like, and the obtained olefin is used as an alkylating agent and reacts with benzene under the catalysis of liquid acid to obtain alkylbenzene. The whole process flow is complex, and the liquid acid is used as the catalyst to produce alkylbenzene, so that the alkylbenzene has serious corrosion to equipment, is not easy to separate from the product, and pollutes the environment. Compared with liquid acid catalysts, the solid acid catalyst is non-toxic, does not easily corrode equipment, can be regenerated and recycled, is environment-friendly, and has wide industrial application prospects. The Fischer-Tropsch synthetic oil is directly used as an alkylating agent to replace a dehydrogenation process, and the coking benzene is used to replace petroleum benzene, so that the synthesis of the full-coal-based long-chain alkyl benzene independent of petroleum resources can be realized.

Patent CN108341735A reports a method for producing C10-C13 linear alkylbenzenes from fischer-tropsch synthesis oil as raw material. The method takes Fischer-Tropsch synthetic oil as a raw material, normal alkane with 10-13 carbon atoms is separated, high-carbon alcohol in the alkane is removed by an extraction tower, and the obtained refined alkane takes hydrofluoric acid as a catalyst to be alkylated with benzene to obtain alkylbenzene. The hydrofluoric acid adopted by the method has great environmental pollution, and meanwhile, the method does not consider the utilization of the alkane and the olefin with the rest carbon numbers in the Fischer-Tropsch synthetic oil, and the high-carbon alcohol in the raw materials needs to be removed, so that the processing cost is increased.

Patent CN1034276C reports that ion exchange modified Y molecular sieve is used as solid acid catalyst to synthesize C10-C16 linear alkyl benzene, fixed bed reactor is adopted, reaction temperature is 100-300 ℃, conversion rate is 99-100%, and selectivity is 99-100%. Regeneration is needed after 40 hours of reaction. Patent CN1077808C reports a Y molecular sieve catalyst subjected to ion exchange and acid treatment. On the catalyst, the direct olefin can be alkylated with benzene to obtain linear alkylbenzene with high conversion rate. The deactivated catalyst may be regenerated by flushing with benzene and alkane. Patent CN1131107C reports a supported heteropolyacid catalyst for use in the alkylation of C10-C14 linear olefins with benzene to produce linear alkylbenzene. The carrier is selected from Y, X, beta, ZSM-12, MCM-11 molecular sieve, active carbon and Al ₂ O ₃ 、SiO ₂ 、TiO ₂ Or the sexual component is heteropoly acid and its salt. Use of solid acid catalysts in catalystsThe main problem with the production of alkanylbenzenes is the poor stability of the catalyst, which requires frequent regeneration.

Disclosure of Invention

The invention aims to produce alkylbenzene with different carbon chain lengths by directly taking different fractions of Fischer-Tropsch synthetic oil products as alkylating agents and alkylating alpha-olefin and coking benzene in the Fischer-Tropsch synthetic oil fractions under the action of a catalyst by utilizing a reaction separation process. Meanwhile, an environment-friendly solid acid catalysis process is adopted to replace a liquid acid process, so that the problems of equipment corrosion, environmental pollution and the like in the existing process can be solved, the fraction section of Fischer-Tropsch synthetic oil can be directly used as a raw material, the high-carbon alcohol separation process is avoided, and the production cost is further reduced. The invention adopts a double bed filling mode in the fixed bed reactor, the upper layer catalyst is used for removing oxygen-containing compounds in materials, and the lower layer catalyst adopts a multi-stage pore molecular sieve for alkylation reaction.

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

a method for realizing Fischer-Tropsch synthesis oil grading utilization by utilizing a reaction separation process comprises the following steps:

(1) Separating Fischer-Tropsch synthetic oil to obtain fractions with different carbon number compositions;

(2) Different fractions obtained by separation in the step (1) are respectively mixed with benzene series, and alkylation reaction is carried out in a fixed bed reactor under the atmosphere of nitrogen;

(3) Cooling and separating the product obtained after the reaction to obtain various linear alkyl benzenes, unreacted benzene series and hydrocarbons;

(4) And (4) recycling the benzene series obtained in the step (3) as a reaction raw material, and taking the hydrocarbons obtained in the step (3) as a byproduct or further deeply processing to prepare a high value-added product.

Further, the benzene series is petroleum-based benzene series or coking benzene series. Preferably a coker benzene series. In particular to one or a mixture of several of benzene, toluene and xylene which are mixed according to any ratio.

Further, the alkylation reaction in the step (2) has the temperature of 160-240 ℃, the pressure of 2-4 MPa and the liquid hourly space velocity of 0.3-5 h ^-1 。

Further, the molar ratio of the benzene series to the fraction in the step (2) is 2-20: 1.

further, two catalysts are filled in the fixed bed reactor in the step (2), the two catalysts are filled in an upper layer and a lower layer, and the reaction materials are firstly contacted with the upper layer catalyst to remove oxygen-containing compounds and then contacted with the lower layer catalyst to carry out alkylation reaction. In the reaction process, the conversion rate of olefin is more than 95%, the selectivity of alkylbenzene is more than 98%, and the total selectivity of 2-position alkylbenzene and 3-position alkylbenzene is more than 70%.

Further, the catalyst is a solid acid catalyst, the upper layer catalyst is medium-pore acid silica-alumina, and the lower layer catalyst is mainly composed of a molecular sieve selected from Beta, Y, ultrastable Y, mercerization, MCM-49, L, SAPO-5, SAPO-11, ZSM-12, ZSM-18 and a mixture thereof.

Further, the lower layer catalyst contains 30wt% -90 wt% of hydrogen type molecular sieve, and the balance is binder.

Further, the average adsorption pore diameter of the molecular sieve is not less than 4nm.

Further, the single-pass life of the solid acid is more than 1000 hours, and the cycle life is more than 40000 hours.

A device for realizing Fischer-Tropsch synthesis oil grading utilization by utilizing a reaction separation process comprises a Fischer-Tropsch synthesis oil separation unit and a plurality of alkylation reaction devices;

alkylation reaction unit includes blender, fixed bed reactor, product separation unit, the ft synthesis oil separation unit is provided with a plurality of discharge gates, matches with a plurality of alkylation reaction unit, the discharge gate of ft synthesis oil separation unit is connected with the first feed inlet of blender, and benzene series thing gets into the blender through the second feed inlet of blender, the discharge gate of blender is connected with fixed bed reactor's feed inlet, fixed bed reactor's discharge gate is connected with product separation unit's pan feeding mouth, the benzene series thing of product separation unit's benzene series thing discharge gate output returns the blender, product separation unit's hydrocarbon discharge gate output hydrocarbon is as the accessory substance or does further deep-processing preparation high added value product, product separation unit's alkylbenzene discharge gate output alkylbenzene.

Compared with the prior art, the invention has the following advantages:

the invention directly utilizes different distillation sections in the Fischer-Tropsch synthetic oil product to be alkylated with the coking benzene under the action of the catalyst to produce the alkylbenzene with different carbon chain lengths, thereby avoiding the alkane and alkene separation process with high energy consumption, realizing the reaction separation of the Fischer-Tropsch synthetic oil, obviously improving the utilization rate and the utilization value of the Fischer-Tropsch synthetic oil product, and realizing the synthesis of the coal-based long-chain alkylbenzene which is completely independent of petroleum resources by combining the utilization of the coking benzene. And simultaneously solves the problems of great environmental hazard and difficult acquisition of alpha-olefin in the traditional alkylbenzene production. By adopting the double-bed catalyst, the adverse effect of oxygen-containing compounds in Fischer-Tropsch synthesis oil on alkylation reaction is avoided, and long-period operation of the fixed bed reactor is realized.

Drawings

FIG. 1 is a schematic diagram of an apparatus for processing Fischer-Tropsch synthetic oil to coal-based linear alkylbenzene.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

Example 1

A device for realizing Fischer-Tropsch synthesis oil classification utilization by utilizing a reaction separation process comprises a Fischer-Tropsch synthesis oil separation unit 9 and four alkylation reaction devices;

the alkylation reaction device comprises a mixer, a fixed bed reactor and a product separation unit, wherein the Fischer-Tropsch synthesis oil separation unit 9 is provided with four discharge ports and is matched with the four alkylation reaction devices;

a first discharge hole of the Fischer-Tropsch synthetic oil separation unit 9 is connected with a first feed hole of the first mixer 1, a second discharge hole is connected with a first feed hole of the second mixer 2, a third discharge hole is connected with a first feed hole of the third mixer 3, and a fourth discharge hole is connected with a first feed hole of the fourth mixer 4 through a pipeline 13;

coking benzene enters through second feed inlets of a first mixer 1, a second mixer 2, a third mixer 3 and a fourth mixer 4 respectively, a discharge outlet of the first mixer 1 is connected with a feed inlet of a first fixed bed reactor 5, a discharge outlet of the second mixer 2 is connected with a feed inlet of a second fixed bed reactor 6, a discharge outlet of the third mixer 3 is connected with a feed inlet of a third fixed bed reactor 7, and a discharge outlet of the fourth mixer 4 is connected with a feed inlet of a fourth fixed bed reactor 8;

the discharge port of the first fixed bed reactor 5 is connected with the feed port of the first product separation unit 10, the discharge port of the second fixed bed reactor 6 is connected with the feed port of the second product separation unit 11, the discharge port of the third fixed bed reactor 7 is connected with the feed port of the third product separation unit 12, and the discharge port of the fourth fixed bed reactor 8 is connected with the feed port of the fourth product separation unit 13;

benzene produced from the benzene discharge ports of the first product separation unit 10, the second product separation unit 11, the third product separation unit 12 and the fourth product separation unit 13 is returned to the mixer through a pump for recycling, hydrocarbons are output from the hydrocarbon discharge ports of the first product separation unit 10, the second product separation unit 11, the third product separation unit 12 and the fourth product separation unit 13 to be used as byproducts or to be further processed to prepare high value-added products, and alkylbenzene is output from the alkylbenzene discharge ports of the first product separation unit 10, the second product separation unit 11, the third product separation unit 12 and the fourth product separation unit 13.

By utilizing the device, the method for producing various linear alkylbenzene by taking Fischer-Tropsch synthetic oil as the raw material comprises the following steps:

(1) Obtaining four fractions of C7-C9, C10-C13, C14-C19 and C20-C24 from Fischer-Tropsch synthetic oil through a Fischer-Tropsch synthetic oil separation unit;

(2) The four fractions obtained by separation in the step (1) are respectively mixed with benzene in a mixer, the molar ratio of the benzene to the olefin in the first mixer 1 and the first mixer 2 is 8, the molar ratio of the benzene to the olefin in the first mixer 3 and the first mixer 4 is 16 ^-1 The upper layer catalyst in the first fixed bed reactor 5 and the second fixed bed reactor 6 is mesoporous acidic silicon-aluminum, the lower layer catalyst contains 30wt% of hydrogen type molecular sieve, and the rest is binder, the average adsorption pore diameter of the molecular sieve is 4nm, the olefin conversion rate is 98%, and the alkylbenzene selectivity is 99%. The reaction temperature of the third fixed bed reactor 7 and the fourth fixed bed reactor 8 is 200 ℃, the reaction pressure is 4MPa, and the airspeed is 0.3h ^-1 The upper layer catalyst in the third fixed bed reactor 7 and the fourth fixed bed reactor 8 is mesoporous acidic silicon-aluminum, the lower layer catalyst contains 50wt% of hydrogen type molecular sieve, the rest is binder, the adsorption average pore diameter of the molecular sieve is 7nm, the conversion rate of olefin is 98%, and the selectivity of alkylbenzene is 99%.

(3) Cooling the products obtained after the reaction, and then respectively entering a first product separation unit 10, a second product separation unit 11, a third product separation unit 12 and a fourth product separation unit 13 to separate and obtain various linear alkylbenzene, unreacted benzene and hydrocarbons;

(4) And (4) recycling the benzene obtained in the step (3) as a reaction raw material, and taking the hydrocarbons obtained in the step (3) as a byproduct or further deeply processing to prepare a high value-added product.

Example 2

A method for realizing Fischer-Tropsch synthesis oil grading utilization by utilizing a reaction separation process comprises the following steps:

(1) Obtaining three fractions of C9-C11, C12-C14 and C15-C24 from the Fischer-Tropsch synthetic oil through a Fischer-Tropsch synthetic oil separation unit;

(2) Mixing the three fractions obtained by separation in the step (1) with benzene in a mixer respectively, wherein the molar ratio of the benzene to the olefin in the first mixer 1 and the first mixer 2 is 10, the molar ratio of the benzene to the olefin in the first mixer 3 is 13, carrying out alkylation reaction in a fixed bed reactor under the nitrogen atmosphere, wherein the reaction temperature of the first fixed bed reactor 5 and the second fixed bed reactor 6 is 180 ℃, the reaction pressure is 2MPa, and the space velocity is 2h ^-1 The upper layer catalyst in the first fixed bed reactor 5 and the second fixed bed reactor 6 is mesoporous acidic silicon-aluminum, the lower layer catalyst contains 50wt% of hydrogen type molecular sieve, and the rest is binder, the adsorption average pore diameter of the molecular sieve is 10nm, the olefin conversion rate is 97%, and the alkylbenzene selectivity is 99%. The reaction temperature of the third fixed bed reactor 7 is 240 ℃, the reaction pressure is 4MPa, and the space velocity is 3h ^-1 In the third fixed bed reactor 7, the upper catalyst is mesoporous acidic silica-alumina, the lower catalyst contains 90wt% of hydrogen type molecular sieve, and the rest is binder, the average adsorption pore diameter of the molecular sieve is 8nm, the olefin conversion rate is 95%, and the alkylbenzene selectivity is 99%.

(3) Cooling the products obtained after the reaction, and then respectively entering a first product separation unit 10, a second product separation unit 11 and a third product separation unit 12 to separate and obtain various linear alkylbenzene, unreacted benzene and hydrocarbons;

(4) And (4) recycling the benzene obtained in the step (3) as a reaction raw material, and taking the hydrocarbons obtained in the step (3) as a byproduct or further deeply processing to prepare a high value-added product.

Claims (8)

1. A method for realizing Fischer-Tropsch synthesis oil grade utilization by using a reaction separation process is characterized by comprising the following steps:

(1) Separating Fischer-Tropsch synthetic oil to obtain fractions with different carbon number compositions;

(2) Different fractions obtained by separation in the step (1) are respectively mixed with benzene series, and alkylation reaction is carried out in a fixed bed reactor under the atmosphere of nitrogen; the fixed bed reactor is filled with two catalysts which are filled in an upper layer and a lower layer, reaction materials firstly contact with the upper layer catalyst to remove oxygen-containing compounds and then contact with the lower layer catalyst to carry out alkylation reaction, the catalysts are solid acid catalysts, the upper layer catalyst is medium-pore acid silicon-aluminum, and the lower layer catalyst mainly comprises a molecular sieve selected from Beta, Y, ultrastable Y, mercerization, MCM-49, L, SAPO-5, SAPO-11, ZSM-12, ZSM-18 and mixtures thereof;

(3) Cooling and separating the product obtained after the reaction to obtain various linear alkylbenzene, unreacted benzene series and hydrocarbons;

(4) And (4) recycling the benzene series obtained in the step (3) as a reaction raw material, and taking the hydrocarbons obtained in the step (3) as a byproduct or further performing deep processing to prepare a high value-added product.

2. The method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 1, wherein the benzene series is petroleum-based benzene series or coking benzene series.

3. The method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 2, characterized in that the benzene series is coking benzene series.

4. The method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 1, wherein the alkylation reaction temperature in the step (2) is 160 to 240 ℃, the pressure is 2 to 4MPa, and the liquid hourly space velocity is 0.3 to 5h ^-1 。

5. The method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 1, wherein the molar ratio of the benzene series to the distillate in the step (2) is 2 to 20:1.

6. the method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 1, wherein the lower layer catalyst contains 30wt% to 90wt% of hydrogen type molecular sieve, and the balance is binder.

7. The method for realizing Fischer-Tropsch synthesis oil grade utilization by using the reaction separation process according to claim 1, wherein the adsorption average pore diameter of the molecular sieve is not less than 4nm.

8. The device applied to the Fischer-Tropsch synthesis oil grading utilization method by utilizing the reaction separation process in claim 1 is characterized by comprising a Fischer-Tropsch synthesis oil separation unit and a plurality of alkylation reaction devices;

alkylation reaction unit includes blender, fixed bed reactor, product separation unit, the ft synthesis oil separation unit is provided with a plurality of discharge gates, matches with a plurality of alkylation reaction unit, the discharge gate of ft synthesis oil separation unit is connected with the first feed inlet of blender, and benzene series thing gets into the blender through the second feed inlet of blender, the discharge gate of blender is connected with fixed bed reactor's feed inlet, fixed bed reactor's discharge gate is connected with product separation unit's pan feeding mouth, the benzene series thing of product separation unit's benzene series thing discharge gate output returns the blender, product separation unit's hydrocarbon discharge gate output hydrocarbon is as the accessory substance or does further deep-processing preparation high added value product, product separation unit's alkylbenzene discharge gate output alkylbenzene.

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