CN112871200A

CN112871200A - Catalyst system for preparing light aromatic hydrocarbon from synthesis gas and application thereof

Info

Publication number: CN112871200A
Application number: CN202110148597.4A
Authority: CN
Inventors: 刘小浩; 胥月兵; 姜枫; 刘冰; 王廷
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2021-02-03
Filing date: 2021-02-03
Publication date: 2021-06-01
Anticipated expiration: 2041-02-03
Also published as: CN112871200B

Abstract

The invention discloses a catalyst system for preparing light aromatic hydrocarbon from synthesis gas and application thereof, belonging to the technical field of synthesis gas conversion. The catalyst system prepared by the invention comprises a Fischer-Tropsch catalyst containing iron and nickel bimetal and a catalyst with an aromatization function, wherein the Fischer-Tropsch catalyst containing iron and nickel bimetal comprises an alloy consisting of iron and nickel elements; wherein, the mole percentage of nickel in the total atoms of iron and nickel is 0.02-30; the catalyst with aromatization function comprises a zeolite molecular sieve and an inert material coating layer, or the zeolite molecular sieve, an auxiliary agent and the inert material coating layer. The catalyst has high catalytic activity and very low-carbon alkane selectivity, the aromatic selectivity reaches over 80 percent, and the light aromatic reaches 90 percent; 70 percent of light aromatic hydrocarbon is dimethylbenzene, and more than 90 percent of light aromatic hydrocarbon is paraxylene with high added value, thus having wide industrial application prospect.

Description

Catalyst system for preparing light aromatic hydrocarbon from synthesis gas and application thereof

Technical Field

The invention relates to a catalyst system for preparing light aromatic hydrocarbon from synthesis gas and application thereof, belonging to the technical field of synthesis gas conversion.

Background

In recent years, as petroleum resources have become increasingly scarce and the price of crude oil has been continuously rising, CO/H produced from natural gas, coal and biomass has been increasing₂The conversion to hydrocarbons and other chemicals over catalysts, and at certain temperatures and pressures, is of great interest to researchers in various countries around the world. Among them, light aromatics (BTX) including Benzene, Toluene and Xylene are important chemical raw materials, which are mainly derived from the cracking of naphtha. As crude oil resources are reduced and environmental issues become more prominent, the access to olefins and aromatics from petroleum routes is challenged and becomes non-sustainable. The limited petroleum resources and environmental crisis have stimulated the research and development of non-petroleum based carbon resource conversion chemistry, and thus the production of aromatics by non-petroleum routes has become more and more important, with syngas (CO + H)₂Or CO₂+H₂) Is a critical connection point through non-petroleum based carbon resources and other basic chemicals.

Carbon-containing resources such as coal, natural gas, biomass and the like can be converted into chemicals such as fuel, alcohol, alkane/olefin and the like through the synthesis gas, the synthesis gas and the carbon dioxide are used for directly preparing low-carbon olefin or aromatic hydrocarbon to serve as a substitute technical route, and the method has important significance for relieving the dependence on petroleum resources by utilizing abundant coal resources in China.

Synthesis gas (CO or CO) has been reported₂) The process for directly preparing aromatic hydrocarbon mainly includes successively placing two catalysts with synthetic gas conversion function and dehydroaromatization function in series-connected double-bed reactor or using granulesOr mixing in particles, such as CN106540740A and CN 106518591A; two sections of reactors adopted by domestic Shanxi coal gasification are respectively filled with two types of catalysts, and synthetic gas can be converted into aromatic hydrocarbon (CN101422743B) through dimethyl ether; the Boyuanjia project group at south Keystin university reports that the selectivity of aromatics at 1.1MPa and 270 ℃ approaches 50% by physically mixing a Fischer-Tropsch synthesis (FTS) catalyst Fe/MnO with a Ga/HZSM-5 catalyst (Catalysis Today, 30 (1-3): 207) -213, 1996). However, when the mixed catalyst of the molecular sieve and the Fischer-Tropsch synthesis is directly adopted, the molecular sieve catalyst is easy to inactivate and is not easy to separate from the Fischer-Tropsch catalyst with high activity in time, and the performance of the Fischer-Tropsch synthesis catalyst can be influenced; in addition, the activity of the Fischer-Tropsch catalyst can be severely affected when the amount of molecular sieve exceeds a certain amount. In addition, the optimum operating conditions for the fischer-tropsch reaction and the aromatization reaction often do not match well. These problems will likely limit the application of syngas or carbon dioxide to aromatics; further, in the current report, the distribution of aromatic hydrocarbon in the liquid phase is very wide, heavy aromatic hydrocarbon is often obtained, and the additional value is very low.

Disclosure of Invention

[ problem ] to provide a method for producing a semiconductor device

At present, in order to remove CO or CO₂The hydrogenation for preparing aromatic compounds mainly has two routes: (1) coupling a catalyst for synthesizing methanol with a molecular sieve; (2) an iron-based fischer-tropsch catalyst is coupled to a molecular sieve. However, in the first route, CO or CO is present₂The conversion rate is low and generally does not exceed 20 percent; meanwhile, the generated aromatic hydrocarbon is mainly heavy aromatic hydrocarbon (the carbon number is more than 9, C)₉₊) High added value C₆-C₈The aromatic content of (A) is very low. Although the conversion in the second route can be greatly improved, the catalyst stability and the aromatic hydrocarbon distribution are still not ideal, and the potential industrial application of the reaction is limited.

[ technical solution ] A

To obtain high CO or CO simultaneously₂High conversion rate, high catalyst stability, high aromatic selectivity and high content of light aromatic hydrocarbon (wherein xylene is mainly p-xylene), and the invention providesA catalyst system for preparing light aromatic hydrocarbon from synthesis gas and a preparation method thereof. The Fischer-Tropsch catalyst part prepared by the method has high activity, high olefin selectivity and high stability; the aromatized part of the preparation can mainly obtain para-xylene; when the two are coupled, high aromatic selectivity and high light aromatic content can be finally obtained. Therefore, the catalyst prepared by the invention has excellent catalytic performance and stability.

The invention provides a catalyst system for synthesizing light aromatic hydrocarbon, which comprises a Fischer-Tropsch catalyst containing iron-nickel bimetal and a catalyst with an aromatization function; wherein, the Fischer-Tropsch catalyst containing the iron-nickel bimetal comprises an alloy formed by iron and nickel elements; wherein, the mole percentage of nickel in the total atoms of iron and nickel is 0.02-30; the catalyst with aromatization function comprises a zeolite molecular sieve and an inert material coating layer, or the zeolite molecular sieve, an auxiliary agent and the inert material coating layer.

Further, the iron-nickel bimetallic Fischer-Tropsch catalyst can contain an auxiliary agent or not contain the auxiliary agent.

Further, when the Fe-Ni bimetallic Fischer-Tropsch catalyst contains an auxiliary agent, the auxiliary agent is one or more than two of lithium, sodium, potassium, sulfur, manganese, cobalt, zinc and copper, and the mass fraction of the auxiliary agent in the catalyst is 0.01-5 wt%.

Furthermore, the auxiliary agent in the catalyst with aromatization function is one or more than two of iron, manganese, cobalt, zinc, copper, molybdenum, tungsten and vanadium, and the mass (calculated by oxide) of the auxiliary agent accounts for 0.1-30 wt% of the aromatization active component.

Furthermore, the inert material coating layer in the catalyst with aromatization function is one or more than two of silicon oxide, aluminum oxide, titanium oxide, carbon material and molecular sieve, and accounts for 0.1-30 wt% of the weight of the catalyst.

Further, the Fischer-Tropsch catalyst part and the aromatization catalyst part in the catalyst system for synthesizing the light aromatic hydrocarbon are carried out in a mode of mixing particles or mixing powder to form particles, and the weight ratio of the Fischer-Tropsch catalyst part to the aromatization catalyst part is 0.1-10.

Further, the iron-nickel bimetallic Fischer-Tropsch catalyst is prepared by the following method:

firstly, mixing soluble salt solutions of iron and nickel according to the iron-nickel atomic ratio or the iron-nickel atomic ratio, and stirring to obtain iron and nickel solutions;

secondly, at 40-95 ℃, adding a precipitator into each hundred milliliters of iron and nickel solution at a rate of 0.1-20 milliliters per minute, adjusting the pH of the solution to 7-13, then aging for 0.5-10 hours, and finally performing solid-liquid separation and washing;

thirdly, drying at 60-200 ℃ for 1-24 hours, and roasting at 300-700 ℃ for 1-24 hours to prepare precipitates containing iron and nickel atoms;

step four, loading required auxiliary agent elements on the precipitate of the bimetal containing iron and nickel by adopting an impregnation method;

when the precipitator contains the auxiliary agent element or the Fischer-Tropsch catalyst containing the iron-nickel bimetal does not need the auxiliary agent, the fourth step can be optionally omitted.

Furthermore, the soluble salt is one or more than two of nitrate, chloride and sulfate.

In one embodiment of the invention, the precipitant is one or more of carbonic acid, sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, ammonia water, sodium hydroxide and potassium hydroxide, and the concentration of the precipitant-containing solution is 0.5-6 mol/L.

Further, the catalyst having an aromatization function is prepared by the following method:

firstly, dipping a molecular sieve into soluble salt containing an auxiliary agent element by adopting an equal volume dipping method, an ion exchange method or an excess dipping method, then removing a solvent by rotary evaporation, drying at 30-250 ℃ for 0-24h, and roasting at 250-700 ℃ for 0.5-24 h;

the first step, the obtained sample is further dipped in an organic compound solution containing inert material precursors, and is continuously stirred for 0-24h, and is subjected to hydrothermal reaction for 5-100h at 50-200 ℃, and then the solvent is removed by rotary evaporation and is dried for 0-24h at 30-250 ℃, and is roasted for 0.5-24h at 250-700 ℃.

Furthermore, the soluble salt of the auxiliary element is one or more than two of nitrate, chloride, sulfate, carbonate, molybdate and tungstate.

Further, the organic compound containing the inert material precursor is one or more of silicon oxide, sodium silicate, propyl orthosilicate, hexamethyldisiloxane, ethyl orthosilicate, isopropyl orthosilicate, aluminum oxide, aluminum isopropoxide trihydrate, sodium aluminate, aluminum sulfate, boehmite or gibbsite.

A method for preparing light aromatic hydrocarbon from synthesis gas takes the catalyst system as a catalyst.

Furthermore, the catalyst system for synthesizing light aromatic hydrocarbon needs to be reduced in pure hydrogen or mixed gas containing hydrogen before use; wherein the reduction temperature is 250-600 ℃, the reduction pressure is 0.1-2MPa, and the reduction space velocity is 500-50000 mL/g/h; the reduction time is 1-48 hours.

Further, the reaction condition of the catalyst system for synthesizing the light aromatic hydrocarbon is that the molar ratio of hydrogen to carbon monoxide or hydrogen to carbon dioxide in the synthesis gas is 0.5-5; the reaction temperature is 150 ℃ and 400 ℃; the reaction pressure is 0.1-5 MPa; the reaction space velocity is 500-100000 mL/g/h.

The catalyst system for synthesizing light aromatic hydrocarbon is applied to the hydrogenation reaction of carbon monoxide or carbon dioxide.

The invention has the beneficial technical effects that:

(1) the catalyst system for synthesizing light aromatic hydrocarbon prepared by the invention has high CO conversion rate, high aromatic hydrocarbon selectivity and high light aromatic hydrocarbon content; low CH₄Selectivity is

(2) The catalyst system for synthesizing light aromatic hydrocarbon prepared by the invention has very high stability.

(3) The catalyst prepared by the invention has the advantages of relatively simple preparation method, high mechanical strength and wide industrial application prospect.

Drawings

The catalyst A in FIG. 1 has an XRD pattern of a Fischer-Tropsch active part after the catalyst is reduced.

Detailed Description

The technical details of the present invention are explained in detail by the following examples.

The catalyst performance evaluation was carried out in a stainless steel fixed bed reactor. 0.5g of the molded Fischer-Tropsch active component and 0.5g of the aromatized active component are physically mixed with 2.5 g of quartz sand, and then the mixture is placed in a reactor and reduced in pure hydrogen of 40ml/min at 400 ℃ and 0.2MPa for 3 hours. After the reduction is finished, the temperature of the catalyst bed is reduced to 200 ℃. Followed by synthesis gas (H)₂：CO：N₂60:30:10, wherein N₂As an internal standard substance) flows through the catalyst bed layer at a certain flow rate, the reaction pressure is gradually increased to 0.5-3MPa, and the reaction temperature is gradually increased to 300-350 ℃ to start the reaction. The product is subjected to cold trap and then is subjected to normal pressure on-line analysis, and the product is analyzed by a gas chromatograph which is simultaneously provided with a thermal conductivity cell and a hydrogen ion flame detector under the chromatographic conditions of a 5A molecular sieve packed column and a

-silica capillary packed column (50 m), programmed temperature rise (initial temperature 50 ℃ for 10 min, followed by 5 ℃/min temperature rise to 200 ℃ for 10 min); the product in the cold trap was analyzed offline by another gas chromatograph equipped with a hydrogen ion flame detector, under the chromatographic conditions of HP-1 capillary packed column (50 m), and temperature programmed (initial temperature 50 ℃ for 5 minutes, followed by 5 ℃/min to 250 ℃ for 10 minutes).

CO conversion rate (moles of inlet CO-moles of outlet CO)/moles of inlet CO × 100%;

product selectivity is the number of moles of product at the outlet x the number of carbon atoms in the product molecule/(moles of CO at the inlet-CO at the outlet) x 100%.

The catalyst system for synthesizing light aromatic hydrocarbon and the preparation method thereof are as follows:

example 1

In the first step, ferric nitrate and nickel nitrate with the atomic ratio of iron to nickel being 5:1 are dissolved in deionized water at 60 ℃, and then 1.5mol/L NaOH solution is added into each hundred milliliters of iron-nickel solution at the dropping speed of 2mL per minute and is intensively stirred until the pH value of the solution is 9.0. Aging the precipitate in mother liquor for 2 hours; then carrying out suction filtration on the precipitate and washing with water to prepare a sample Fischer-Tropsch active component containing Na; these samples were then oven dried at 120 ℃ for 5 hours and subsequently fired in a muffle furnace at 500 ℃ for 5 hours; finally, tabletting, crushing and screening the prepared catalyst to obtain 20-40 mesh particles. By ICP element analysis, the atomic ratio of iron and nickel in the catalyst is basically 5:1, and the content of Na element in the catalyst is 0.67 wt%. The sample is reduced and then is characterized by XRD (figure 1), and the prepared sample catalyst is an iron-nickel bimetallic compound containing iron-nickel alloy.

Secondly, taking a certain amount of HZSM-5 molecular sieve, wherein the silicon-aluminum ratio (Si/Al) is 15, soaking an ammonium molybdate solution into the molecular sieve by adopting an isometric soaking method, then performing rotary evaporation to remove a solvent, drying at 120 ℃ for 5 hours, and roasting at 550 ℃ for 5 hours; then, the obtained sample is immersed in a solution with the mass ratio of tetraethoxysilane, CTAB, ethanol and water being 1:0.8:1:0.5, continuously stirred for 12 hours, and then placed in a hydrothermal kettle for reaction for 24 hours at the temperature of 150 ℃; cooling, taking out, separating, drying at 120 deg.C for 12 hr, and calcining at 500 deg.C for 5 hr to obtain SiO₂The coated Mo-containing molecular sieve. Finally, tabletting, crushing and screening the prepared catalyst to obtain 20-40 mesh particles. After ICP analysis, the Mo content in the sample was 4.5 wt%, SiO₂The content of the coating was 12.1 wt%.

Thirdly, 0.5g of each sample prepared in the first step and the second step is taken and fully and physically mixed to obtain the product which can be used for dissolving CO or CO₂A catalytic system A for synthesizing light aromatic hydrocarbon by hydrogenation.

Example 2

Taking 4g of the sample obtained in the first step of example 1 and 0.5g of the sample obtained in the second step of example 1, mixing them physically and thoroughly to obtain a mixture of CO or CO₂A catalytic system A1 for synthesizing light aromatic hydrocarbon by hydrogenation.

Example 3

Taking 0.5g of sample obtained in the first step of example 1 and 4g of sample obtained in the second step of example 1, mixing them physically and thoroughly to obtain a mixture of CO or CO₂A catalytic system A2 for synthesizing light aromatic hydrocarbon by hydrogenation.

Example 4

Firstly, according to the iron and nickel raw materialsFerric sulphate and nickel sulphate in a sub-ratio of 5:1 were dissolved in deionized water at 65 ℃ and then 3.0mol/L aqueous ammonia solution was added to each hundred mL of iron-nickel solution at a drop rate of 1mL per minute and stirred vigorously until the pH of the solution reached 9.0. Aging the precipitate in mother liquor for 2 hours; then carrying out suction filtration on the precipitate, washing with water, drying at 150 ℃ for 5 hours, and drying at 550 ℃ for 5 hours; then adopting an equal-volume impregnation method to impregnate the roasted substance into the solution containing Na₂In the solution of S, spin-evaporating to remove the solvent, putting the sample in a 120 ℃ oven for drying for 5 hours, and roasting in a muffle furnace at 500 ℃ for 5 hours; finally, tabletting, crushing and screening the prepared catalyst to obtain 20-40 mesh particles. By ICP element analysis, the atomic ratio of Fe to Ni in the catalyst is basically 5:1, the content of Na element in the catalyst is 0.74 wt%, and the content of S element is 0.46 wt%.

The second and third steps, like in example 1, gave a catalytic system B.

Example 5

The ratio of iron atoms to nickel atoms in the first step in the example 4 is 4:1 from 5:1, and the rest steps and operations are unchanged; the resulting catalyst system is C. Wherein the catalyst with the Fischer-Tropsch catalytic active part has a Na content of 0.54 wt% and an S content of 0.36 wt%.

Example 6

The ratio of iron atoms to nickel atoms in the first step in the example 4 is 3:1 from 5:1, and the rest steps and operations are unchanged; the resulting catalytic system is D. Wherein the catalyst with the Fischer-Tropsch catalytic active part has a Na content of 0.51 wt% and an S content of 0.34 wt%.

Example 7

Na in the first step of example 4₂Changing S to Na₂SO₄The other steps and operations are unchanged; the resulting catalytic system is E. Wherein the catalyst with the Fischer-Tropsch catalytic active part has a Na content of 0.58 wt% and an S content of 0.39 wt%.

Example 8

Na in the first step of example 4₂Changing S to MnSO₄The other steps and operations are unchanged; the resulting catalyst system is F. Wherein the Mn content in the catalyst having the Fischer-Tropsch catalytic active portion is 1.24 wt% and an S content of 0.49 wt%.

Example 9

Changing the ammonium molybdate in the second step in the embodiment 1 into zinc nitrate, and keeping the rest of the operations and steps unchanged; the resulting catalyst system is G. Wherein the Zn content in the catalyst having the aromatization catalytic active portion is 3.4 wt%, SiO₂The content was 11.8 wt%.

Example 10

Changing the ammonium molybdate in the second step in the embodiment 1 into cobalt nitrate, and keeping the rest of the operations and steps unchanged; the resulting catalyst system is H. Wherein the Co content of the catalyst with aromatization catalytic active part is 2.8 wt%, and SiO₂The content was 11.4 wt%.

Example 11

Changing the ammonium molybdate in the second step in the embodiment 1 into cobalt tungstate, and keeping the rest of the operations and steps unchanged; the obtained catalytic system is I. Wherein the W content of the catalyst having the aromatization catalytic active portion is 3.4 wt%, SiO₂The content was 10.8 wt%.

Example 12

Changing the ammonium molybdate in the second step in the embodiment 1 into vanadium chloride, and keeping the rest of the operations and steps unchanged; the resulting catalyst system is J. Wherein the catalyst having the aromatization catalytic active portion has a V content of 4.1 wt% and SiO₂The content was 12.1 wt%.

Example 13

Na in the first step of example 4₂Changing S to KNO₃The rest operations and steps are unchanged; the resulting catalyst system is K. Wherein the K content in the catalyst with the Fischer-Tropsch catalytic active part is 1.34 wt%.

Example 14

Na in the first step of example 4₂Changing S to Cu (NO)₃)₂The rest operations and steps are unchanged; the resulting catalyst system is L. Wherein the Cu content in the catalyst with the Fischer-Tropsch catalytic active part is 2.14 wt%.

Example 15

Na in the first step of example 4₂Changing S to Zn (NO)₃)₂The rest operations and steps are unchanged; the obtained catalystThe system is M. Wherein the Zn content in the catalyst with the Fischer-Tropsch catalytic active part is 2.22 wt%.

Application of catalyst system for synthesizing light aromatic hydrocarbon in carbon monoxide hydrogenation reaction

The catalyst system A-M is placed in a fixed bed reactor and continuously reacts for 500 hours under the reaction conditions of 320 ℃, 1.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in table 1.

TABLE 1 catalytic Properties of the different catalysts (A to M)

As can be seen from the results in Table 1, the catalytic system prepared by the catalyst preparation method of the invention has very high catalytic activity (the conversion rate of CO is more than 80%) to synthesis gas and ultrahigh stability, and basically does not deactivate in the activity evaluation of 500 hours; meanwhile, the catalyst has extremely high aromatic selectivity (more than 80 percent), wherein the selectivity of light aromatic hydrocarbon (BTX) is basically over 70 percent, and the content of the light aromatic hydrocarbon in the aromatic hydrocarbon is about 90 percent. In particular, the xylene content in light aromatics amounts to 70%, of which approximately 90% is para-xylene.

Example 16

The catalyst C is placed in a fixed bed reactor and continuously reacted for 500 hours under the reaction conditions of 340 ℃, 2.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in Table 2.

Example 17

The catalyst C is placed in a fixed bed reactor and continuously reacted for 500 hours under the reaction conditions of 340 ℃, 3.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in Table 2.

Example 18

Putting the catalyst C in a fixed bed reactor, and changing the reaction raw material into CO₂/H₂/N₂(volume ratio 3:1:1), reaction was continued at 320 ℃ under 1.0MPa and 5000mL/g/h for 500 hours. The average conversion and the individual product selectivity or distribution results are shown in Table 2.

Example 19

Putting the catalyst C in a fixed bed reactor, and changing the reaction raw material into CO₂/H₂/N₂(volume ratio 3:1:1), reaction was continued at 340 ℃ under 2.0MPa and 5000mL/g/h for 500 hours. The average conversion and the individual product selectivity or distribution results are shown in Table 2.

TABLE 2 catalytic performance of catalyst C under different reaction conditions

It can be seen from table 2 that the catalyst of the present invention has a CO conversion rate approaching 100% at higher reaction temperature and shows very high stability; the selectivity of light aromatic hydrocarbon in the reaction product can be further improved. In CO₂In the hydrogenation reaction, the product selectivity is similar.

Comparative example 1

Iron oxide and nickel oxide were prepared separately by precipitation as in example 1 and then physically mixed in an iron to nickel atomic ratio of 5:1 to give a fischer-tropsch reaction part composition (Na content of 0.47 wt% by ICP analysis); the other catalyst preparation steps were the same as in example 1. The catalytic system is marked as N, and CO hydrogenation performance evaluation is carried out in a fixed bed reactor under the evaluation conditions of 320 ℃, 1.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in Table 3.

Comparative example 2

The nickel element in example 1 and example 3 was changed to manganese element (i.e., manganese nitrate), and the remaining steps and operations were not changed. The obtained catalytic systems are O and P, and the CO hydrogenation performance evaluation is carried out in a fixed bed reactor under the evaluation conditions of 320 ℃, 1.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in Table 3.

Comparative example 3

The atomic ratio of iron to nickel in the examples is changed from 5:1 to 1:1, and the rest steps and operations are not changed. The obtained catalytic system is Q, and the CO hydrogenation performance evaluation is carried out in a fixed bed reactor under the evaluation conditions of 320 ℃, 1.0MPa and 5000 mL/g/h. The average conversion and the individual product selectivity or distribution results are shown in Table 3.

TABLE 3 catalytic Performance of catalysts H-K for CO hydrogenation

As can be seen from the results in Table 3, when only iron and nickel oxides are simply physically mixed (comparative example 1) or the nickel content is excessively high (comparative example 3), although the conversion of CO is very high, the products are mainly low-carbon saturated alkanes, particularly CH₄The selectivity of the substance reaches more than 85 percent. Secondly, when the nickel element is changed into the manganese element (comparative example 2), the number of low-carbon saturated alkanes is increased, and the aromatic hydrocarbon products are mainly heavy aromatic hydrocarbon; and the catalyst is quickly deactivated in the subsequent 50 hours, and the CO conversion rate is reduced to below 30 percent.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A catalyst system for synthesizing light aromatic hydrocarbon is characterized in that the catalyst system for synthesizing the light aromatic hydrocarbon comprises a Fischer-Tropsch catalyst containing iron-nickel bimetal and a catalyst with aromatization function; wherein, the Fischer-Tropsch catalyst containing the iron-nickel bimetal comprises an alloy formed by iron and nickel elements; wherein, the mole percentage of nickel in the total atoms of iron and nickel is 0.02-30; the catalyst with aromatization function comprises a zeolite molecular sieve and an inert material coating layer, or the zeolite molecular sieve, an auxiliary agent and the inert material coating layer.

2. The catalyst system of claim 1, wherein the iron-nickel bimetallic Fischer-Tropsch catalyst further comprises an auxiliary agent, the auxiliary agent is one or more of lithium, sodium, potassium, rubidium, sulfur, nitrogen, manganese, cobalt, zinc and copper, and the mass fraction of the auxiliary agent in the catalyst is 0.01-5 wt%.

3. The catalyst system according to claim 1 or 2, wherein the auxiliary agent in the catalyst with aromatization function is one or more of lithium, sodium, potassium, rubidium, iron, manganese, cobalt, zinc, copper, molybdenum, tungsten, rhenium and vanadium, and the mass (calculated by oxide) accounts for 0.1-30 wt% of the aromatization active component; the inert material coating layer is one or more than two of silicon oxide, aluminum oxide, titanium oxide, carbon materials and molecular sieves, and accounts for 0.1-30 wt% of the catalyst.

4. The catalyst system according to any one of claims 1 to 3, wherein the Fischer-Tropsch active component and the aromatization active component of the catalyst system for synthesizing light aromatic hydrocarbons are mixed in the form of particles or mixed in powder to form particles, and the weight ratio of the Fischer-Tropsch active component to the aromatization active component is 0.1-10.

5. The catalyst system of any one of claims 1 to 4, wherein the iron-nickel bimetallic containing Fischer-Tropsch catalyst is prepared by a method comprising:

6. The catalyst system of claim 5, wherein the precipitant is one or more selected from the group consisting of carbonic acid, sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, aqueous ammonia, sodium hydroxide, and potassium hydroxide.

7. The catalyst system according to any one of claims 1 to 6, characterized in that the catalyst having an aromatization function is prepared by the following method:

8. A method for preparing light aromatic hydrocarbons from synthesis gas, which is characterized in that the catalyst system of any one of claims 1 to 7 is used as a catalyst.

9. The method for preparing light aromatic hydrocarbons from synthesis gas according to claim 8, wherein the catalyst system for synthesizing light aromatic hydrocarbons is required to be reduced in pure hydrogen or a hydrogen-containing mixed gas before use; wherein the reduction temperature is 250-600 ℃, the reduction pressure is 0.1-2MPa, and the reduction space velocity is 500-50000 mL/g/h; the reduction time is 1-48 hours.

10. The method for preparing light aromatic hydrocarbons from synthesis gas according to claim 8, wherein the reaction conditions of the catalyst system for synthesizing light aromatic hydrocarbons are that the molar ratio of hydrogen to carbon monoxide or hydrogen to carbon dioxide in the synthesis gas is 0.5-5; the reaction temperature is 150 ℃ and 400 ℃; the reaction pressure is 0.1-5 MPa; the reaction space velocity is 500-100000 mL/g/h.