A method for preparing aromatic hydrocarbons

Abstract

The present application discloses a method for preparing aromatic hydrocarbons. The method includes feeding a raw material containing naphtha and CO2 into a reactor filled with a zeolite molecular sieve catalyst to carry out a reaction to generate aromatic hydrocarbons. The method of the present application provides a new technical route for large-scale production of aromatic hydrocarbons using CO2, and this method overcomes the defects of limited hydrogen resources and high cost in the prior art. By using the method of the present application, the selectivity of aromatic hydrocarbons is as high as 71.64%.

Description

Technical Field

[0001] The present invention belongs to the field of petrochemical industry, and particularly relates to a method for preparing aromatic hydrocarbons, and more particularly to a method for catalytically coupling naphtha and CO2 to convert them into aromatic hydrocarbons by using a zeolite molecular sieve catalyst. Background Art

[0002] Aromatic hydrocarbons (especially the three benzenes, namely benzene, toluene and xylene, and xylene includes ortho-xylene, meta-xylene and para-xylene) are basic chemical raw materials. Industrially, aromatic hydrocarbons are mainly obtained by catalytic reforming of naphtha and extraction of cracked gasoline by-produced from ethylene plants (the main raw material is naphtha). Therefore, a large part of aromatic hydrocarbons comes from the technology of producing aromatic hydrocarbons from naphtha. Among them, the aromatic hydrocarbons produced by catalytic reforming of naphtha account for 80% of the petroleum-based aromatic hydrocarbons.

[0003] With the development of modern industry, carbon dioxide (CO2), as the main greenhouse gas, its concentration in the atmosphere is increasing day by day, and thus the greenhouse effect is becoming increasingly prominent. In 2020, the global CO2 emissions have reached 34 billion tons. Therefore, the recovery, fixation and resource utilization of CO2 have become issues of great concern to countries around the world. From the perspective of resources, CO2 is the cheapest carbon one resource in the world. Therefore, vigorously developing CO2 utilization technology, especially converting CO2 into aromatic hydrocarbons, has important economic and social significance. On the one hand, it can solve the shortage of chemical products in China, and on the other hand, due to the large market scale of aromatic hydrocarbon products, it can achieve large-scale CO2 emission reduction.

[0004] It is disclosed in the prior art that CO2 is hydrogenated to prepare aromatic hydrocarbons. Research shows that in this process, CO2 is first activated under the action of a first catalyst, and then the intermediate components generated by reacting with hydrogen undergo processes such as carbon chain growth, transfer and ring formation under the action of a second catalyst to generate aromatic hydrocarbons. At present, the above processes are all to produce liquid hydrocarbons or aromatic hydrocarbons by hydrogenating CO2. In addition to technical indicators, the source of hydrogen is also a key issue restricting its industrial application. Summary of the Invention

[0005] In order to solve the above technical problems, the inventors of the present application creatively found that using naphtha as a raw material and coupling it with CO2 as a raw material to produce aromatic hydrocarbons is a new technical route for using CO2 to produce aromatic hydrocarbons, providing a new way for aromatic hydrocarbon production and large-scale utilization of CO2.

[0006] The present application provides a method for preparing aromatic hydrocarbons, characterized in that a raw material containing naphtha and CO2 is introduced into a reactor equipped with a zeolite molecular sieve catalyst to react to produce aromatic hydrocarbons.

[0007] Optionally, the zeolite molecular sieve catalyst comprises a zeolite molecular sieve, the pore size of the zeolite molecular sieve is 0.35 - 0.8 nm, and the zeolite molecular sieve has an acidic structure.

[0008] In this application, the "aperture size" of the zeolite molecular sieve refers to the length of the aperture in any dimension direction.

[0009] Optionally, the zeolite molecular sieve catalyst is composed of a zeolite molecular sieve.

[0010] Optionally, the zeolite molecular sieve is selected from at least one of zeolite molecular sieves with topological structures of MFI, MEL, FER, and BEA.

[0011] Optionally, the zeolite molecular sieve is selected from at least one of HZSM-5, HZSM-11, HZSM-35, and Hβ hydrogen-type zeolite molecular sieves.

[0012] Optionally, the silicon-aluminum atomic ratio of the zeolite molecular sieve is 15 - 50.

[0013] Optionally, the silicon-aluminum atomic ratio of the zeolite molecular sieve is 15 - 20.

[0014] Optionally, the zeolite molecular sieve catalyst further contains a binder.

[0015] In this application, the preparation method of the zeolite molecular sieve catalyst for fluidized bed is as follows: Mix the hydrogen-type zeolite molecular sieve and the binder evenly in water, obtain a slurry through beating, colloid milling, and defoaming, and obtain the zeolite molecular sieve for fluidized bed through conventional spray drying forming and roasting; wherein the binder includes an amorphous binder containing aluminum or silicon, preferably pseudoboehmite or silica sol.

[0016] Optionally, the raw material consists of naphtha and CO2.

[0017] Optionally, the naphtha is selected from at least one of hydrocracked naphtha, catalytically cracked naphtha, raffinate oil, topped oil, and direct coal liquefaction naphtha.

[0018] Optionally, the carbon number distribution range of the hydrocarbons in the naphtha is C4 - C 12 .

[0019] Optionally, the reactor is one of a fixed bed reactor, a fluidized bed reactor, or a moving bed reactor.

[0020] Optionally, the reaction conditions are: the reaction temperature is 450 - 650 °C, the reaction pressure is 0.1 - 3 MPa, the weight hourly space velocity of the naphtha is 0.1 - 5 h -1 , and the weight hourly space velocity of CO2 is 0.1 - 5 h -1 .

[0021] Optionally, the reaction temperature is selected from any value among 450 °C, 500 °C and 650 °C, or a range value determined by any two of these values.

[0022] Optionally, the reaction pressure is selected from any value among 0.1 MPa, 1 MPa and 3 MPa, or a range value determined by any two of these values.

[0023] Optionally, the weight hourly space velocity of the naphtha is selected from 0.1 h -1 -1 -1 -1 -1 and 5 h

[0024] Optionally, the weight hourly space velocity of CO2 is selected from 0.1 h -1 -1 -1 -1 -1 and 5 h

[0025] Optionally, the reaction time is 30 minutes to 120 minutes.

[0026] Optionally, the mass ratio of CO2 to naphtha is 1:3 to 10:1.

[0027] Optionally, the mass ratio of CO2 to naphtha is a range value determined by any two of 1:3, 1:1, and 10:1.

[0028] Specifically, the preparation method of the above-mentioned method for the coupled conversion of naphtha and CO2 to aromatics is as follows:

[0029] (1) Load the zeolite molecular sieve catalyst into the reactor, first pre-treat it with an inert gas such as nitrogen at a predetermined temperature, and cool it to the reaction temperature under a nitrogen atmosphere;

[0030] (2) Feed naphtha and CO2, where naphtha is fed using a micro-feed pump and the feed rate of CO2 is controlled by a flow meter, and control the reaction pressure within a predetermined range;

[0031] (3) After naphtha and CO2 react for a predetermined time, analyze the products by gas chromatography.

[0032] The "hydrocracked naphtha" in this application refers to heavy naphtha produced by the hydrocracking reaction of heavy oil.

[0033] The "catalytically cracked naphtha" in this application refers to naphtha produced by the catalytic cracking of vacuum gas oil and atmospheric residue.

[0034] The "extracted oil" in this application refers to the fraction oil remaining after extracting aromatics from the catalytic reformate rich in aromatics. The "topped oil" in this application refers to the light fraction with a boiling point lower than 60 °C obtained during the distillation of straight-run gasoline.

[0035] The "coal direct liquefaction naphtha" in this application refers to the naphtha produced by a coal direct liquefaction unit.

[0036] In this application, the coupling conversion of naphtha and CO2 to aromatics means that CO2 reacts with naphtha as a raw material to prepare aromatics.

[0037] The beneficial effects that this application can produce include:

[0038] 1) This application provides a new technical route for large-scale production of aromatics using CO2, which overcomes the defects of limited hydrogen resources and high costs in the prior art.

[0039] 2) Using the method of this application, the selectivity of aromatics is as high as 71.64%. Detailed implementation manners

[0040] The following describes this application in detail in conjunction with the embodiments, but this application is not limited to these embodiments.

[0041] In the ranges disclosed in this application, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include those close to these ranges or values. For numerical ranges, between the endpoint values and the individual point values of each range, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0042] The following describes this application in detail in conjunction with the embodiments, but this application is not limited to these embodiments.

[0043] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels or prepared by known methods. The zeolite molecular sieve raw powder in the embodiments is purchased from the Catalyst Factory of Nankai University.

[0044] Unless otherwise specified, the analysis methods in the embodiments all adopt the conventional settings and conventional analysis methods of the instruments or equipment.

[0045] In the embodiments of this application, the type of naphtha is coal direct liquefaction naphtha, and its specific composition is shown in the following table:

[0046] Composition of coal direct liquefaction naphtha

[0047] Carbon number n - alkane iso - alkane Naphthene Aromatic hydrocarbon 6 0.03 0.00 0.00 0.00 7 3.76 0.71 31.85 1.60 8 9.36 2.62 27.53 1.94 9 2.03 2.44 13.88 0.40 10 0.15 0.75 0.74 0.07 11 0.01 0.03 0.10 0.00 Total 15.34 6.55 74.10 4.01

[0048] In the embodiments of the present application, the inner diameter of the fixed-bed reactor is 1.5 cm; the inner diameter of the fixed fluidized-bed reactor is 3 cm.

[0049] In the products of the embodiments of the present application, only hydrocarbon products are listed, and other products generated by the reaction of naphtha and CO2 are not enumerated.

[0050] Example 1 Preparation of a shaped molecular sieve sample of HZSM-5 for a fixed bed

[0051] After calcining 100 g of the original powder of HZSM-5 zeolite molecular sieve (manufactured by the Catalyst Factory of Nankai University, Si / Al = 15) in an air atmosphere at 550 °C for 4 hours, it was tableted, crushed, and sieved to obtain shaped molecular sieve particles with a particle size of 40 - 60 mesh, denoted as FXHZSM-5.

[0052] Example 2 Preparation of a shaped molecular sieve sample of HZSM-11 for a fixed bed

[0053] After calcining 100 g of the original powder of HZSM-11 zeolite molecular sieve (manufactured by the Catalyst Factory of Nankai University, Si / Al = 15) in an air atmosphere at 550 °C for 4 hours, it was tableted, crushed, and sieved to obtain shaped molecular sieve particles with a particle size of 40 - 60 mesh, denoted as FXHZSM-11.

[0054] Example 3 Preparation of a shaped molecular sieve sample of HZSM-35 for a fixed bed

[0055] After calcining 100 g of the original powder of HZSM-35 zeolite molecular sieve (manufactured by the Catalyst Factory of Nankai University, Si / Al = 20) in an air atmosphere at 550 °C for 4 hours, it was tableted, crushed, and sieved to obtain shaped molecular sieve particles with a particle size of 40 - 60 mesh, denoted as FXHZSM-35.

[0056] Example 4 Preparation of a shaped molecular sieve sample of Hβ for a fixed bed

[0057] After calcining 100 g of the original powder of Hβ zeolite molecular sieve (manufactured by the Catalyst Factory of Nankai University, Si / Al = 20) in an air atmosphere at 550 °C for 4 hours, it was tableted, crushed, and sieved to obtain shaped molecular sieve particles with a particle size of 40 - 60 mesh, denoted as FXHβ.

[0058] Example 5 Preparation of a shaped molecular sieve sample of HZSM-5 for a fluidized bed

[0059] Mix 100 g of the original powder of HZSM-5 zeolite molecular sieve (manufactured by the Catalyst Factory of Nankai University, Si / Al = 15) with an amorphous binder containing aluminum or silicon and spray-dry to form a shape. The specific steps are as follows:

[0060] Mix the raw powder of HZSM-5 zeolite molecular sieve, pseudo-boehmite, silica sol, xanthan gum (bio-gum) and water evenly, and obtain a slurry through beating, colloid milling and defoaming; the weight parts of each component in the slurry are as follows:

[0061]

[0062] The obtained slurry is formed by spray drying to obtain a microsphere particle sample with a particle size distribution of 20-100 μm; after the microsphere particle sample is calcined in a muffle furnace at 550 °C for 3 hours, an HZSM-5 formed molecular sieve with an attrition index of 1.2 is obtained, denoted as FLHZSM-5.

[0063] Reaction performance of the fixed-bed catalyst FXHZSM-5 in Example 6

[0064] Evaluate the coupling conversion reaction performance of naphtha and CO2 of the catalyst in a micro fixed-bed reaction device. The evaluation conditions are as follows: Load 5 g (40-60 mesh) of the formed molecular sieve sample FXHZSM-5 into the fixed-bed reactor, first treat it with 50 mL / min of nitrogen at 550 °C for 1 hour, and then adjust the temperature to the reaction temperature of 550 °C in a nitrogen atmosphere; the naphtha raw material is fed by a micro-feed pump, and the CO2 flow rate is controlled by a mass flowmeter. The raw material CO2:naphtha (mass ratio)=1:3, and the weight hourly space velocity of CO2 is = 0.33 h -1 , the weight hourly space velocity of naphtha is 1 h -1 , and the reaction pressure is 1 MPa. The reaction products are analyzed by an on-line Agilent 7890 gas chromatograph, and samples are taken for analysis at 30 min of the reaction. The reaction results are shown in Table 1.

[0065] Table 1 Evaluation of the reaction performance of the catalyst in Example 6

[0066]

[0067]

[0068] Reaction performance of the fixed-bed catalyst FXHZSM-11 in Example 7

[0069] Evaluate the coupling conversion reaction performance of naphtha and CO2 of the catalyst in a micro fixed-bed reaction device. The evaluation conditions are as follows: Load 5 g (40-60 mesh) of the formed molecular sieve sample FXHZSM-11 into the fixed-bed reactor, first treat it with 50 mL / min of nitrogen at 550 °C for 1 hour, and then adjust the temperature to the reaction temperature of 550 °C in a nitrogen atmosphere; the naphtha raw material is fed by a micro-feed pump, and the CO2 flow rate is controlled by a mass flowmeter. The raw material CO2:naphtha (mass ratio)=1:3, and the weight hourly space velocity of CO2 is = 0.33 h -1 , the weight hourly space velocity of naphtha is 1 h -1, the reaction pressure is 1 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis after 30 min of reaction. The reaction results are shown in Table 2.

[0070] Table 2 Evaluation of the reaction performance of the catalyst in Example 7

[0071]

[0072]

[0073] Reaction performance of the fixed-bed catalyst FXHZSM-35 in Example 8

[0074] The reaction performance of the catalyst for the coupled conversion of naphtha and CO2 was evaluated in a micro fixed-bed reactor. The evaluation conditions were as follows: 5 g (40-60 mesh) of the shaped molecular sieve sample FXHZSM-35 was loaded into the fixed-bed reactor, first treated with 50 mL / min of nitrogen at 550 °C for 1 hour, and then the temperature was adjusted to the reaction temperature of 550 °C in a nitrogen atmosphere; the naphtha raw material was fed by a micro-feeding pump, the CO2 flow rate was controlled by a mass flow meter, the raw material CO2:naphtha (mass ratio) = 1:3, and the weight hourly space velocity of CO2 was = 0.33 h -1 , the weight hourly space velocity of naphtha is 1 h -1 , the reaction pressure is 1 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis after 30 min of reaction. The reaction results are shown in Table 3.

[0075] Table 3 Evaluation of the reaction performance of the catalyst in Example 8

[0076]

[0077]

[0078] Reaction performance of the fixed-bed catalyst FXHβ in Example 9

[0079] The reaction performance of the catalyst for the coupled conversion of naphtha and CO2 was evaluated in a micro fixed-bed reactor. The evaluation conditions were as follows: 5 g (40-60 mesh) of the shaped molecular sieve sample FXHβ was loaded into the fixed-bed reactor, first treated with 50 mL / min of nitrogen at 550 °C for 1 hour, and then the temperature was adjusted to the reaction temperature of 550 °C in a nitrogen atmosphere; the naphtha raw material was fed by a micro-feeding pump, the CO2 flow rate was controlled by a mass flow meter, the raw material CO2:naphtha (mass ratio) = 1:3, and the weight hourly space velocity of CO2 was = 0.33 h -1 , the weight hourly space velocity of naphtha is 1 h -1, the reaction pressure was 1 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis at 30 min of the reaction. The reaction results are shown in Table 4.

[0080] Table 4 Evaluation of the reaction performance of the catalyst in Example 9

[0081]

[0082]

[0083] Reaction performance of the fluidized bed catalyst FLHZSM-5 in Example 10

[0084] The coupling conversion reaction performance of the catalyst for naphtha and CO2 was evaluated in a micro fixed fluidized bed reaction device. The evaluation conditions were as follows: 20 g (100-200 mesh) of the shaped molecular sieve sample FLHZSM-5 was loaded into the fixed bed reactor, first treated with 50 mL / min of nitrogen at 550 °C for 1 hour, and then the temperature was adjusted to the reaction temperature of 550 °C under a nitrogen atmosphere; the naphtha raw material was fed by a micro-feed pump, and the CO2 flow rate was controlled by a mass flow meter. The raw material CO2:naphtha (mass ratio) = 1:3, and the weight hourly space velocity of CO2 was = 0.33 h -1 , the weight hourly space velocity of naphtha was 1 h -1 , the reaction pressure was 0.3 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis at 30 min of the reaction. The reaction results are shown in Table 5.

[0085] Table 5 Evaluation of the reaction performance of the catalyst in Example 10

[0086]

[0087] Reaction performance of the fixed bed catalyst FXHZSM-5 in Example 11

[0088] Except that the CO2 in Example 6 was replaced with an equimolar amount of N2 (i.e., the mass ratio of N2:naphtha was 1:4.7), other conditions were the same as those in Example 6.

[0089] Table 6 Evaluation of the reaction performance of the catalyst in Example 11

[0090]

[0091] In Example 11, N2 was used as a diluent; while in Example 6, CO2 was used as a raw material for reacting with naphtha, which can be reflected by comparing the aromatic selectivity of Examples 6 and 11. Specifically, the aromatic selectivity in Example 6 was significantly higher than that in Example 11.

[0092] Reaction Performance of Fixed-Bed Catalyst FXHZSM-5 in Example 12

[0093] The coupled conversion reaction performance of the catalyst for naphtha and CO2 was evaluated in a micro fixed-bed reaction device. The evaluation conditions were as follows: 5 g (40 - 60 mesh) of the shaped molecular sieve sample FXHZSM-5 was loaded into the fixed-bed reactor. First, it was treated with 50 mL / min of nitrogen at 550 °C for 1 hour, and then the temperature was adjusted to the reaction temperature of 550 °C in a nitrogen atmosphere. The naphtha raw material was fed by a micro-feed pump, and the CO2 flow rate was controlled by a mass flow meter. The raw material CO2:naphtha (mass ratio) = 1:1, the weight hourly space velocity of CO2 was = 5 h -1 , and the weight hourly space velocity of naphtha was 5 h -1 , and the reaction pressure was 3 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis at 30 min of the reaction. The reaction results are shown in Table 7.

[0094] Table 7 Evaluation of the Reaction Performance of the Catalyst in Example 12

[0095]

[0096] Reaction Performance of Fixed-Bed Catalyst FXHZSM-5 in Example 13

[0097] The coupled conversion reaction performance of the catalyst for naphtha and CO2 was evaluated in a micro fixed-bed reaction device. The evaluation conditions were as follows: 5 g (40 - 60 mesh) of the shaped molecular sieve sample FXHZSM-5 was loaded into the fixed-bed reactor. First, it was treated with 50 mL / min of nitrogen at 550 °C for 1 hour, and then the temperature was adjusted to the reaction temperature of 550 °C in a nitrogen atmosphere. The naphtha raw material was fed by a micro-feed pump, and the CO2 flow rate was controlled by a mass flow meter. The raw material CO2:naphtha (mass ratio) = 1:1, the weight hourly space velocity of CO2 was = 0.1 h -1 , and the weight hourly space velocity of naphtha was 0.1 h -1 , and the reaction pressure was 0.1 MPa. The reaction products were analyzed by on-line Agilent 7890 gas chromatography, and samples were taken for analysis at 30 min of the reaction. The reaction results are shown in Table 8.

[0098] Table 8 Evaluation of the Reaction Performance of the Catalyst in Example 13

[0099]

[0100] In addition to the naphtha used in the above examples, the present application can also use any naphtha selected from hydrocracked naphtha, catalytically cracked naphtha, raffinate oil, topped oil or any mixture thereof.

[0101] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the relevant art can make some changes or modifications within the scope of the technical solution of the present application by using the disclosed technical content, which are equivalent to equivalent embodiments and all fall within the scope of the technical solution.

Claims

1. A method for preparing an aromatic hydrocarbon, characterized in that, The method includes feeding a raw material containing naphtha and CO2 into a reactor filled with a zeolite molecular sieve catalyst to carry out a reaction to produce aromatics; The reaction conditions are as follows: the reaction temperature is 450 - 650 °C, the reaction pressure is 0.1 - 3 MPa, the weight hourly space velocity of the naphtha is 0.1 - 5 h -1 , and the weight hourly space velocity of CO2 is 0.1 - 5 h -1 ; The zeolite molecular sieve catalyst contains a zeolite molecular sieve, the pore size of the zeolite molecular sieve is 0.35 - 0.8 nm, and the zeolite molecular sieve has an acidic structure; The zeolite molecular sieve is selected from at least one of zeolite molecular sieves with MFI, MEL, FER, and BEA topological structures; The carbon number distribution range of hydrocarbons in the naphtha is C4-C 12 .

2. The method according to claim 1, wherein The zeolite molecular sieve catalyst is composed of a zeolite molecular sieve.

3. The method according to claim 1 or 2, characterized in that, The zeolite molecular sieve is selected from at least one of HZSM-5, HZSM-11, HZSM-35, and Hβ hydrogen-type zeolite molecular sieves.

4. The method according to claim 1 or 2, characterized in that, The silicon-aluminum atomic ratio of the zeolite molecular sieve is 15 - 50.

5. The method according to claim 1 or 2, characterized in that, The silicon-aluminum atomic ratio of the zeolite molecular sieve is 15 - 20.

6. The method according to claim 1, wherein The zeolite molecular sieve catalyst further contains a binder.

7. The method according to claim 1, characterized in that The raw material is composed of naphtha and CO2.

8. The method according to claim 1, wherein The naphtha is selected from at least one of hydrocracked naphtha, catalytically cracked naphtha, raffinate oil, topped oil, and direct coal liquefaction naphtha.

9. The method according to claim 1, wherein The reactor is one of a fixed-bed reactor, a fluidized-bed reactor, or a moving-bed reactor.

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