CN114797956A

CN114797956A - Composite catalyst, preparation method and application thereof, and preparation method of heavy aromatic hydrocarbon

Info

Publication number: CN114797956A
Application number: CN202210501820.3A
Authority: CN
Inventors: 刘殿华; 王子豪
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2022-05-09
Filing date: 2022-05-09
Publication date: 2022-07-29
Anticipated expiration: 2042-05-09
Also published as: CN114797956B

Abstract

The application provides a composite catalyst, a preparation method and application thereof, and a preparation method of heavy aromatic hydrocarbon, wherein the composite catalyst comprises the following components in parts by weight: a modified zinc aluminum catalyst comprising: porous zinc-aluminum composite particles, and first metal particles bonded to the surfaces of the porous zinc-aluminum composite particles; and a modified HZSM-5 molecular sieve comprising: an HZSM-5 molecular sieve, and second metal particles bound to the surface of the HZSM-5 molecular sieve; wherein, the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve are compounded into the composite catalyst. The composite catalyst provided by the application has high thermal stability, can control the generation rate of intermediate products in the reaction of preparing heavy aromatic hydrocarbon from synthesis gas so as to prepare products, has the CO conversion rate of over 58 percent in the reaction process, has the selectivity of tetramethylbenzene in the products of 46.71 percent, and has good industrial application prospect.

Description

Composite catalyst, preparation method and application thereof, and preparation method of heavy aromatic hydrocarbon

Technical Field

The application relates to the technical field of synthesis gas conversion, in particular to a composite catalyst, a preparation method and application thereof, and a preparation method of heavy aromatic hydrocarbon.

Background

During the process of preparing aromatic hydrocarbon by the synthetic gas through a methanol route one-step method, the heavy aromatic hydrocarbon with high selectivity and more than carbon ten can be obtained. Durene in the main product can be used as a fine chemical raw material, and the demand is increased year by year. Durene is oxidized and polymerized to obtain polyimide which can be used for manufacturing engineering plastics with excellent high temperature resistance, radiation resistance, impact resistance and insulating property, is widely applied to aerospace industry, electronics industry and military industry, and is more used for preparing high-performance membrane materials and carbon dioxide capture application in recent years.

The traditional durene preparation usually uses a pseudocumene alkylation process, and the pseudocumene yield is limited by the yield of an aromatization industry and a mixed aromatic separation process, so that the durene production scale is difficult to expand. Therefore, the characteristics of poor oil, less gas and rich coal of petrochemical resources in China are combined. The synthesis gas prepared from coal is gradually mature, and has great strategic significance for the reasonable and effective application of the synthesis gas.

At present, the process for preparing aromatic hydrocarbon from synthesis gas mostly uses a Fischer-Tropsch catalyst and a molecular sieve to produce light aromatic hydrocarbon, but produces C ₉ The above heavy aromatics have been studied relatively rarely.

According to the search, the Chinese patent application with the publication number of CN112521241A discloses a method for preparing durene by coupling carbon monoxide and methanol, wherein the durene is prepared by using ZSM-5, MCM-22, MCM-49 and a BETA molecular sieve HZSM-5 molecular sieve, and the durene selectivity in the product can reach 95%.

And Chinese patent application with publication number CN103864562A, which discloses a method for preparing durene from methanol, wherein ZSM-5 is modified by hydrothermal treatment to obtain C rich in durene ₁₀₊ Heavy aromatic hydrocarbon component and Ni and Pt metal modified ZSM-5 molecular sieve are cracked into light aromatic hydrocarbon, and the yield of tetramethylbenzene can reach 35%. However, in the above two patents, methanol is mainly used as the feed material, the catalyst main body is used as the molecular sieve, and the high selectivity of preparing durene from methanol is achieved by the coupling feed of carbon monoxide and the regulation and control of the acid strength of the molecular sieve.

Further retrieval shows that patent application with publication number CN106565406A discloses a one-step method for preparing durene, which comprises the steps of taking synthesis gas as a starting material, impregnating modified molecular sieve ZSM-5 with Nb and Ni through a copper-based catalyst, and carrying out one-step catalytic reaction to prepare durene, wherein the total yield of the durene can reach 52%. The patent uses a coupling mode of a copper-based catalyst and a molecular sieve to prepare durene by a one-step method, but the copper-based catalyst has poor thermal stability and is easy to sinter and inactivate in the high-temperature coupling use process.

Disclosure of Invention

In order to solve the technical problems, the application provides a composite catalyst, a preparation method and an application thereof, and a preparation method of heavy aromatic hydrocarbon.

In a first aspect, the present application provides a composite catalyst comprising:

a modified zinc aluminum catalyst comprising: porous zinc-aluminum composite particles, and first metal particles bound to the surfaces of the porous zinc-aluminum composite particles; and the combination of (a) and (b),

a modified HZSM-5 molecular sieve comprising: an HZSM-5 molecular sieve, and second metal particles bound to the surface of the HZSM-5 molecular sieve;

wherein the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve are compounded into a composite catalyst.

Optionally, in some embodiments herein, the first metal particles are any one of iron, copper, chromium, or manganese; and/or the second metal particles are any one of copper, zinc or niobium.

Optionally, in some embodiments of the present application, the mass ratio of the first metal particles to the porous zinc-aluminum composite particles is (2:100) - (17: 100); and/or the mass ratio of the second metal particles to the HZSM-5 molecular sieve is (1:100) - (11: 100).

Optionally, in some embodiments herein, the mass ratio of the modified zinc aluminum catalyst to the modified HZSM-5 molecular sieve is 1 (0.5-5).

Optionally, in some embodiments of the present application, the porous zinc-aluminum composite particles have a specific surface area of 70m ² /g-250m ² Per g, pore volume of 0.10cm ³ /g-0.45cm ³ And/or the microscopic morphology of the porous zinc-aluminum composite particles is in a layered petal structure.

Optionally, in some embodiments herein, the modified zinc-aluminum catalyst has a specific surface area of 125m ² /g-300m ² Per g, pore volume 0.10cm ³ /g-0.25cm ³ /g。

In a second aspect of the present application, there is provided a method for preparing a composite catalyst, comprising:

preparing a modified zinc-aluminum catalyst: providing porous zinc-aluminum composite particles, mixing a solution of first metal particles with the porous zinc-aluminum composite particles, and modifying the porous zinc-aluminum composite particles by the first metal particles through impregnation to obtain a modified zinc-aluminum catalyst;

preparing a modified HZSM-5 molecular sieve: mixing a solution of second metal particles with an HZSM-5 molecular sieve, and modifying the HZSM-5 molecular sieve by the second metal particles through impregnation to obtain a modified HZSM-5 molecular sieve;

and mixing the modified zinc-aluminum catalyst with the modified HZSM-5 molecular sieve to obtain the composite catalyst.

Optionally, in some embodiments of the present application, the modified zinc aluminum catalyst is mixed with the modified HZSM-5 molecular sieve in a mass ratio of 1 (0.5-5).

Optionally, in some embodiments of the present application, the porous zinc-aluminum composite particle is prepared by the following steps:

zinc salt, aluminum salt, an auxiliary agent and deionized water are mixed according to a molar ratio of 1: (0.01-5.0): (0-7.5): 5-20) to prepare a solution A;

mixing sodium salt and deionized water to prepare 0.1-1.0M solution B;

and adding the solution B into the solution A, adjusting the pH value to a set value, keeping stirring at the set temperature during the period, washing to obtain a product, and then drying and roasting in sequence to obtain the porous zinc-aluminum composite particles.

Optionally, in some embodiments of the present application, the first metal particles are impregnated in an amount of 2% to 5% by mass of the porous zinc-aluminum composite particles.

Optionally, in some embodiments herein, the second metal particles are impregnated in an amount of 1% to 10% by mass of the HZSM-5 molecular sieve.

The third aspect of the application is to provide the application of the composite catalyst in preparing heavy aromatic hydrocarbon by using synthesis gas.

In a fourth aspect of the present application, a method for preparing heavy aromatic hydrocarbons is provided, which includes the following steps:

the synthesis gas is used as a raw material, and CO and H in the synthesis gas are catalyzed by the composite catalyst ₂ Generating an intermediate product methanol on the surface of the modified zinc-aluminum catalyst, carrying out aromatization reaction in pore channels of the modified HZSM-5 molecular sieve under the mixed filling condition of the composite catalyst to generate a series of aromatic compounds, and carrying out alkylation reaction outside the pore channels of the modified HZSM-5 molecular sieve to obtain a reaction product;

and carrying out gas-liquid separation on the reaction product to obtain a liquid phase product containing the target product heavy aromatic hydrocarbon.

The heavy aromatic hydrocarbon means C ₁₀₊ Including but not limited to tetramethylbenzene, durene.

The applicant researches and discovers that in the process of preparing aromatic hydrocarbon from synthesis gas, the high-selectivity production of durene can be realized just in one reactor by compounding the high-activity methanol catalyst and the high-acidity molecular sieve. The novel preparation method of durene mainly adopts methanol feeding or synthesis gas feeding, so that durene is directly prepared from synthesis gas, the preparation cost of a reactor and the transportation cost of intermediate products are greatly reduced, and the one-step preparation method has high application potential. The heavy aromatic hydrocarbon product is obtained by the synergistic effect of aromatization and alkylation reactions in the optimized reaction through the design and modification of the catalyst, and has higher production and application values.

The application has one or more of the following beneficial effects:

the modified zinc-aluminum catalyst is obtained by modifying porous zinc-aluminum composite particles through first metal particles, the porous zinc-aluminum composite particles have petal-shaped structural morphology, the specific surface area is high, the pore volume is large, metal load modification is further suitable, the modified porous zinc-aluminum composite particles are high in thermal stability in catalytic reaction, the modified porous zinc-aluminum composite particles can be operated at the temperature of 360-420 ℃ with the modified HZSM-5 molecular sieve, the reaction temperature of the modified porous zinc-aluminum composite particles is well matched with that of the modified HZSM-5 molecular sieve, the high-temperature CO conversion rate is high under the coupling of series reaction of the modified porous zinc-aluminum composite particles and the modified HZSM-5 molecular sieve, and the high selectivity of tetramethylbenzene is further realized by adjusting the conversion rate.

The application, the porous zinc-aluminum composite particles with the petal-shaped morphology and the interlayer structure screen out the modified zinc-aluminum catalyst with high conversion rate through various metal impregnation loads, adjust the reaction activity of the catalyst, directly influence the generation amount of intermediate product methanol, and can control the aromatic hydrocarbon distribution of the product through proper amount of metal modification.

The composite catalyst provided by the application is applied to the reaction of preparing the heavy aromatics from the synthesis gas, and realizes that the heavy aromatics (including but not limited to tetramethylbenzene) is prepared from the synthesis gas through one-step catalytic reaction, namely, the tetramethylbenzene (the main product is durene) is directly produced through the series reaction in the same reactor, the conversion rate of CO is further improved, and the concentration of the provided intermediate product methanol just meets the aromatization and alkylation treatment capacities of the modified HZSM-5 molecular sieve. The CO conversion rate in the raw material gas (or synthesis gas) reaches 58%, the selectivity of the product tetramethylbenzene can reach 64%, and the selectivity of durene can reach 46.71%. Has good industrial application prospect and is beneficial to reasonably utilizing the coal resources in China.

Compared with a copper-based catalyst and a modified molecular sieve combined catalyst used for synthesizing aromatic hydrocarbon in a Chinese patent with publication number CN106565406A in the prior art, the porous zinc-aluminum composite particle adopted in the method has the characteristics of easiness in modification, stronger plasticity, higher thermal stability of the modified zinc-aluminum catalyst, more stable use and capability of controlling the generation rate of an intermediate product so as to prepare a product.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 shows the morphology of the porous zinc-aluminum composite particles provided by the present application under a scanning electron microscope.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention.

The present application provides a composite catalyst, a preparation method and an application thereof, and a preparation method of heavy aromatics, which are described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments of the present application. In the following embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to related descriptions of other embodiments for parts that are not described in detail in a certain embodiment.

The embodiment of the application provides a composite catalyst, which is formed by compounding a modified zinc-aluminum catalyst and a modified HZSM-5 molecular sieve. In some embodiments, the mass ratio of the modified zinc aluminum catalyst to the modified HZSM-5 molecular sieve is 1 (0.5 to 5).

The modified zinc-aluminum catalyst comprises: the catalyst comprises porous zinc-aluminum composite particles and first metal particles combined on the surfaces of the porous zinc-aluminum composite particles, wherein the porous zinc-aluminum composite particles are modified by the first metal particles, so that the performance of the catalyst is improved. The first metal particles are reactive metals. The porous zinc-aluminum composite particles are modified by active metal, so that the performance of the catalyst is favorably adjusted, and the reaction conversion rate is effectively controlled. In some embodiments, the first metal particles are any of iron, copper, chromium, or manganese. The modified zinc-aluminum catalyst with high conversion rate is screened out by the porous zinc-aluminum composite particles modified by any metal of iron, copper, chromium or manganese, so that the reaction activity of the catalyst is adjusted, the conversion rate of CO is improved, and the generation amount of intermediate product methanol is directly influenced. Preferably, the manganese modified zinc-aluminum composite particles exhibit the best reaction activity in experiments, which is beneficial to improving the selectivity of tetramethylbenzene. The first metal particles are not limited to any of iron, copper, chromium, and manganese, and other active metals having a function of preparing a catalyst may be used.

The modified HZSM-5 molecular sieve comprises: HZSM-5 molecular sieve, and second metal particles combined on the surface of the HZSM-5 molecular sieve, wherein the second metal particles modify the HZSM-5 molecular sieve. The second metal particles are reactive metals. The second metal particles may be any one of copper, zinc or niobium, but are not limited thereto. The modified HZSM-5 molecular sieve is a high-acidity molecular sieve.

Aromatizing by using the topological structure of the H-ZSM molecular sieve to generate aromatic compounds as main products. The acidity of the HZSM-5 molecular sieve is adjusted through metal modification, and acid sites on the surface of the modified HZSM-5 molecular sieve are more suitable for alkylation reaction of aromatic hydrocarbon, so that generation of heavy aromatic hydrocarbon is promoted.

In specific implementation, the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve form a composite catalyst in a mechanical mixing mode, the composite catalyst is utilized to realize series reaction in the same reactor to directly produce tetramethylbenzene, the CO conversion rate is further improved, and the concentration of the provided intermediate product methanol just meets the aromatization and alkylation treatment capacity of the modified HZSM-5 molecular sieve after metal modification.

In other embodiments of the present application, the mass ratio of the first metal particles to the porous zinc-aluminum composite particles is (2:100) - (17: 100); and/or the mass ratio of the second metal particles to the HZSM-5 molecular sieve is (1:100) - (11: 100). The porous zinc-aluminum composite particles and the HZSM-5 molecular sieve are modified by proper amount of metal, which is beneficial to controlling the heavy aromatic hydrocarbon distribution of the product, can pertinently select the aromatic hydrocarbon product distribution and is beneficial to obtaining the target product tetramethylbenzene with high selectivity. For example, in one specific example, the use of a 7% by weight manganese (Mn) modified zinc aluminum catalyst in combination with a 3% by weight Nb modified commercial HZSM-5 molecular sieve showed the highest CO conversion of 58.95%, where the aromatics product was more selective towards heavy aromatics, particularly tetramethylbenzene, and the tetramethylbenzene selectivity was 46.71%.

In other embodiments of the present application, the porous zinc-aluminum composite particles have a specific surface area of 70m ² /g-250m ² Per g, pore volume of 0.10cm ³ /g-0.45cm ³ (ii) in terms of/g. The porous zinc-aluminum composite particles have high specific surface area and high pore volume, and further improve the reactivity and the modifiability of the particles. Referring to fig. 1, the porous zinc-aluminum composite particles have a multi-layer petal-shaped microstructure under a scanning electron microscope, and have a high specific surface area.

In other embodiments of the present application, the modified zinc aluminum catalyst has a specific surface area of 125m ² /g-300m ² Per g, pore volume of 0.10cm ³ /g-0.25cm ³ And/g, the metal is impregnated and modified to form a particle cluster on the catalytic surface, and the microstructure surface defects of the metal are increased under a transmission electron microscope, so that the reaction activity is enhanced, and the catalytic effect is improved.

Correspondingly, the embodiment of the application also provides a preparation method of the composite catalyst, which comprises the following steps:

s1, preparing a modified zinc-aluminum catalyst:

providing porous zinc-aluminum composite particles, mixing a solution of first metal particles with the porous zinc-aluminum composite particles, and modifying the porous zinc-aluminum composite particles by the first metal particles through impregnation to obtain the modified zinc-aluminum catalyst.

In the above step, the solution of the first metal particles may be an iron nitrate solution, a copper nitrate solution, a chromium nitrate solution, or a manganese nitrate solution, and of course, other salt solutions of iron, copper, chromium, or manganese may also be used. The porous zinc-aluminum composite particles can be specifically modified by equal-volume impregnation.

In some embodiments, the modified zinc aluminum catalyst can be prepared using the following specific steps:

the metal salt solution is formulated using any of iron, copper, chromium, manganese nitrates.

Adding the prepared metal salt solution into the porous zinc-aluminum composite particles, and placing the porous zinc-aluminum composite particles in an ultrasonic pool for impregnation, wherein the impregnation amount of the first metal particles is 2-15% of the mass of the porous zinc-aluminum composite particles by the mass of the active metal. In specific implementation, the following process parameters can be adopted for impregnation: the temperature of the ultrasonic pool is 20-80 ℃ for 1-2 h.

And drying after impregnation to obtain the porous metal modified zinc-aluminum catalyst. In specific implementation, the drying treatment is performed in an oven, and the following process parameters can be adopted: drying in an oven at 80-120 deg.C for 10-24 h, and calcining at 200-600 deg.C for 2-6 h.

The porous zinc-aluminum composite particles can be prepared by a conventional sol precipitation method, wherein the Zn/Al molar ratio is 1-5. The preparation process can adopt one auxiliary agent prepared from oxalic acid, cane sugar and glucose, and the using amount of the auxiliary agent is 0-10g per 0.045mol Al. The porous zinc-aluminum composite particles prepared by the sol precipitation method have the characteristics of low preparation cost, petal-shaped structure morphology, high specific surface area, large pore volume, suitability for metal load modification, high thermal stability in catalytic reaction and capability of being matched with the working temperature of a molecular sieve.

In some embodiments, the porous zinc-aluminum composite particles can be prepared using the following steps:

mixing zinc salt, aluminum salt, auxiliary agent and deionized water to prepare a solution A, and placing the solution A in a water bath at 70-80 ℃. The zinc salt can adopt zinc nitrate, the aluminum salt can adopt aluminum nitrate, and the auxiliary agent can adopt oxalic acid. The mol ratio of zinc nitrate, aluminum nitrate, oxalic acid and deionized water is 1: (0.01-5.0):(0-7.5):(5-20).

Mixing the sodium salt and deionized water to prepare 0.1-1.0M solution B. Sodium carbonate can be used as the sodium salt.

Solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and a temperature of 70-80 ℃. Then continuing to age and stir for 1h-2h, and performing suction filtration and washing twice, wherein 100ml-600ml deionized water is used for washing each time. And drying the obtained product in an oven for 10-24 h, and roasting in a muffle furnace at 400 ℃ for 2-6 h to obtain the porous zinc-aluminum composite particles.

S2, preparing a modified HZSM-5 molecular sieve:

and mixing the solution of the second metal particles with the HZSM-5 molecular sieve, and modifying the HZSM-5 molecular sieve by the second metal particles through impregnation to obtain the modified HZSM-5 molecular sieve.

In the above step, the solution of the second metal particles may be a copper nitrate, zinc nitrate or niobium nitrate solution, but other salt solutions of copper, zinc or niobium may also be used.

In some embodiments, the modified HZSM-5 molecular sieve may be prepared by the following steps:

the metal salt solution is formulated using at least one metal of the group consisting of copper, zinc, niobium nitrates.

And adding the metal salt solution into a commercial HZSM-5 molecular sieve for impregnation, wherein the impregnation amount of the second metal particles is 1-10% of the mass of the HZSM-5 molecular sieve based on the mass of the active metal. In specific implementation, the technological parameters of impregnation are as follows: standing at 20-80 deg.C for 4-24 h.

And after the impregnation is finished, separating the HZSM-5 molecular sieve, washing to be neutral, drying the obtained product, and drying to obtain the modified HZSM-5 molecular sieve. In specific implementation, the following process parameters can be adopted for the drying treatment: drying at 80-120 deg.C for 5-18 h, and calcining at 200-600 deg.C for 1-6 h.

S3, mixing the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve according to the mass ratio of 1 (0.5-5) to obtain the composite catalyst. It should be noted that the mixing in step S3 can be performed by conventional mechanical and physical mixing means which can achieve uniform mixing.

The embodiment of the application also provides an application of the composite catalyst, and the composite catalyst provided by the embodiment is used for preparing heavy aromatic hydrocarbon, and the application comprises the following steps:

the composite catalyst is arranged on a catalyst bed layer in a 20-200 mesh mode.

Synthesis gas (CO + H) ₂ ) Taking the volume ratio of 1:2 as raw material, preheating the synthesis gasFeeding into a fixed bed reactor. It should be noted that the following process parameters can be adopted for preheating: from 150 ℃ to 280 ℃ and most preferably 180 ℃.

The synthesis gas is used as a raw material, and CO and H in the synthesis gas are catalyzed by the composite catalyst ₂ Generating an intermediate product methanol on the surface of a modified zinc-aluminum catalyst, contacting the generated methanol with a modified HZSM-5 molecular sieve catalyst in situ under the mixed filling condition of the composite catalyst, performing aromatization reaction in pore channels of the modified HZSM-5 molecular sieve to generate a series of aromatic compounds, and performing alkylation reaction outside the pore channels of the modified HZSM-5 molecular sieve to obtain a reaction product; the methanol synthesis reaction and the aromatization synthesis durene reaction form a series reaction to realize one-step preparation of the heavy aromatics.

In the steps, the modified zinc-aluminum catalyst is adopted, the carrier of the modified zinc-aluminum catalyst is porous zinc-aluminum composite particles with the shape of an interlayer petal-shaped structure, the specific surface area is high, the pore volume is large, the modified porous zinc-aluminum composite particles are further suitable for metal load modification, the thermal stability of the modified porous zinc-aluminum composite particles in catalytic reaction is high, the CO conversion rate is improved, and the concentration of the generated intermediate product methanol just meets the aromatization and alkylation treatment capacity of the modified HZSM-5 molecular sieve under the catalytic action of the modified porous zinc-aluminum composite particles, so that the aromatization reaction is immediately carried out after the methanol is generated, the accumulation of the methanol is avoided, and the reaction balance is always moved towards the direction of the generation of tetramethylbenzene. Since the reaction proceeds while the reaction is being carried out, the reaction equilibrium proceeds unidirectionally, and the conversion rate is high. Because of the in-situ reaction, the raw materials and the products can be in quick contact and directional contact.

It should be noted that the following process conditions can be adopted for the synthesis reaction: the reaction operation temperature can be 280-400 ℃, the reaction operation pressure is 2.0-5.0 Mpa, and the space velocity of the synthesis gas is controlled at 360 mL.h ^-1 ·gcat ^-1 -3600mL·h ^-1 ·gcat ^-1 The method is favorable for improving the conversion rate of CO and further favorable for improving the selectivity of tetramethylbenzene. The most preferable reaction conditions are that the reaction operating temperature is 320 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the synthetic gas is 900 mL.h ^-1 ·gcat ^-1 . Space velocity means the unit volume under specific conditionsThe amount of feedstock treated per unit time by the catalyst.

The gas-liquid separation can be realized by adopting conventional gravity settling, inertial collision, centrifugal separation, electrostatic attraction, diffusion and other modes.

In order to make the details and operation of the above-mentioned embodiments of the present invention clearly understood by those skilled in the art and to make the composite catalyst of the embodiments of the present invention, the preparation method and application thereof obviously show the progress, the technical solutions are illustrated by the following examples.

The reagents used in the following examples are shown in table 1:

name of reagent	Chemical formula (II)	Specification of	Manufacturer of the product
				Zinc nitrate	Zn(NO ₃ ) ₆ ·6H ₂ O	Analytical purity	SHANGHAI TITAN TECHNOLOGY Co.,Ltd.
Aluminium nitrate	Al(NO ₃ ) ₃ ·9H ₂ O	Analytical purity	SHANGHAI TITAN TECHNOLOGY Co.,Ltd.
				Ferric nitrate	Fe(NO ₃ ) ₃ ·9H ₂ O	Analytical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
Copper nitrate	Cu(NO ₃ ) ₂ ·3H ₂ O	Analytical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
				50% manganese nitrate solution	Mn(NO ₃ ) ₂	Analytical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
Sodium carbonate	Na ₂ CO ₃	Analytical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
				Niobium nitrate	NbO(NO ₃ ) ₂	Analytical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.

The CO conversion and product selectivity are calculated as follows:

in the formula (1), χ _CO Denotes the conversion of CO, n _CO,in And n _CO,out Respectively representing the mole numbers of an inlet and an outlet of CO; in the formula (2), I represents the carbon content of the reaction product I and represents the mole number of the reaction product I.

Example 1

The preparation method of the porous zinc-aluminum composite particles comprises the following steps:

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles are white powder in appearance, show a layered petal-shaped structure appearance under an electron microscope, and have the BET specific surface area of 135.9m ² Per g, pore volume of 0.283cm ³ In terms of a/g, the mean pore diameter is 8.35 nm.

Weighing 5g of porous zinc-aluminum composite particles, dropwise adding deionized water into the porous zinc-aluminum composite particles, and when the porous zinc-aluminum composite particles absorb water until the saturated surfaces are fully wetted and bonded, wherein the amount of the dropwise added water is the saturated water absorption capacity of the porous zinc-aluminum composite particles. According to the saturated water absorption capacity, a manganese nitrate solution with a certain mass concentration is prepared by using a 50% manganese nitrate solution and deionized water, the manganese nitrate solution with the saturated water absorption capacity is dripped into unmodified porous zinc-aluminum composite particles, the loading capacity of manganese elements reaches 2%, the particles are placed in an ultrasonic pool at the temperature of 40 ℃ for 2 hours, dried in a postoven at the temperature of 110 ℃ for 12 hours, and baked in a muffle furnace at the temperature of 400 DEG CAnd (4) burning for 4 hours to obtain the Mn modified zinc-aluminum catalyst with the loading of 2%. The appearance of the modified zinc-aluminum catalyst is light brown powder, and the BET specific surface area is 161.3m ² Per g, pore volume 0.269cm ³ In terms of a/g, the mean pore diameter is 6.15 nm.

Weighing 5g of commercial HZSM-5 molecular sieve, dripping deionized water into the HZSM-5 molecular sieve, and when the HZSM-5 molecular sieve absorbs water until the saturated surface is fully wet and bonded, wherein the amount of the dripped water is the saturated water absorption capacity of the zinc-aluminum catalyst. According to the saturated water absorption capacity, niobium nitrate solution with a certain mass concentration is prepared by using niobium nitrate and deionized water, and the niobium nitrate solution with the saturated water absorption capacity is dripped into a commercial HZSM-5 molecular sieve, so that the load capacity of niobium element reaches 3%. Standing at room temperature for 10h, drying the obtained product in a drying oven at 110 ℃ for 12h, and roasting in a muffle furnace at 550 ℃ for 5h to obtain the Nb modified HZSM-5 molecular sieve, namely the modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is white powder in appearance, the Si/Al molar ratio of the modified HZSM-5 molecular sieve to the modified HZSM-5 molecular sieve is 50, and the pore volume of the modified HZSM-5 molecular sieve is 0.597cm ³ Per g, BET specific surface area 397.9m ² In terms of a/g, the mean pore diameter is 6.01 nm.

The compounding method comprises the following steps:

and mixing the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve according to the mass ratio of 1:2 to obtain the composite catalyst.

The evaluation of the performance of the composite catalyst comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7, also known as synthesis gas) is heated to 180 ℃ by a preheater and enters a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operation temperature of the composite catalyst in the reaction process is 360 ℃, the reaction operation pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with the composite catalyst in the reaction tube, and then the methanol synthesis and aromatization series reaction is carried out, the reaction product is subjected to gas-liquid separation, the liquid-phase product contains trace methanol, water and aliphatic hydrocarbon, various aromatic hydrocarbons comprise a target product durene, and the gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

The reaction products were analyzed by gas-liquid separator, the liquid product was analyzed by Clarus 580 gas chromatograph of PerkinElmer, USA, and the gas product was analyzed by GC900 gas chromatograph produced by Shanghai Tianpu instrument, and the reaction results are shown in Table 2.

Example 2

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles are white powder in appearance, show a layered petal-shaped structure appearance under an electron microscope, and have the BET specific surface area of 135.9m ² Per g, pore volume of 0.283cm ³ In terms of a/g, the mean pore diameter is 8.35 nm.

Weighing 5g of porous zinc-aluminum composite particles, dropwise adding deionized water into the porous zinc-aluminum composite particles, and when the porous zinc-aluminum composite particles absorb water until the saturated surfaces are fully wet and bonded, wherein the amount of the dropwise added water is the saturated water absorption amount of the porous zinc-aluminum composite particles. According to the saturated water absorption capacity, a manganese nitrate solution with a certain mass concentration is prepared by using a 50% manganese nitrate solution and deionized water, the manganese nitrate solution with the saturated water absorption capacity is dripped into an unmodified zinc-aluminum catalyst, the loading capacity of manganese elements reaches 10%, the mixture is placed in an ultrasonic pool at the temperature of 40 ℃ for 2 hours, dried in a postoven at the temperature of 110 ℃ for 12 hours, and roasted in a muffle furnace at the temperature of 400 ℃ for 4 hours, so that the modified zinc-aluminum catalyst with the loading capacity of 10% Mn is obtained. The appearance of the modified zinc-aluminum catalyst is dark brown powder, and the BET specific surface area is 161.3m ² Per g, pore volume 0.269cm ³ In terms of a/g, the mean pore diameter is 6.15 nm.

Commercial ZSM-5 catalyst was used. Commercial molecular sieve parameters: the pore volume is 0.340cm3/g, the BET specific surface area is 289m2/g, the average pore diameter is 4.71nm, and the silica-alumina ratio is 50.

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7, also known as synthesis gas) is heated to 180 ℃ by a preheater and enters a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 360 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube to carry out a series reaction of methanol synthesis and aromatization, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water and aliphatic hydrocarbon, various aromatic hydrocarbons comprise a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

Example 3

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The appearance of the catalyst is white powder, the catalyst shows a layered petal structure shape under an electron microscope, and the BET specific surface area is 135.9m ² Per g, pore volume of 0.283cm ³ In g, average pore diameter of8.35nm。

Weighing 5g of commercial HZSM-5 molecular sieve, dripping deionized water into the HZSM-5 molecular sieve, and when the HZSM-5 molecular sieve absorbs water until the saturated surface is fully wet and bonded, wherein the amount of the dripped water is the saturated water absorption capacity of the zinc-aluminum catalyst. According to the saturated water absorption capacity, niobium nitrate solution with a certain mass concentration is prepared by using niobium nitrate and deionized water, and the niobium nitrate solution with the saturated water absorption capacity is dripped into a commercial HZSM-5 molecular sieve catalyst, so that the load capacity of niobium element reaches 3%. Standing at room temperature for 10h, drying the obtained product in a drying oven at 110 ℃ for 12h, and roasting in a muffle furnace at 550 ℃ for 5h to obtain the Nb modified HZSM-5 molecular sieve, namely the modified HZSM-5 molecular sieve. The appearance of the catalyst is white powder, the Si/Al molar ratio of the catalyst to the catalyst is 50, and the pore volume is 0.597cm ³ Per g, BET specific surface area 397.9m ² In terms of a/g, the mean pore diameter is 6.01 nm.

The compounding method comprises the following steps:

and mixing the porous zinc-aluminum composite particles with a modified HZSM-5 molecular sieve according to the mass ratio of 1:2 to obtain the composite catalyst.

Example 4

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles are white powder in appearance and have a BET specific surface area of 135.9m ² Per g, pore volume of 0.283cm ³ In terms of a/g, the mean pore diameter is 8.35 nm.

Weighing 5g of porous zinc-aluminum composite particles, dropwise adding deionized water into the porous zinc-aluminum composite particles, and when the porous zinc-aluminum composite particles absorb water until the saturated surfaces are fully wet and bonded, wherein the amount of the dropwise added water is the saturated water absorption amount of the porous zinc-aluminum composite particles. According to the saturated water absorption capacity, ferric nitrate and deionized water are used for preparing a ferric nitrate solution with a certain mass concentration, the ferric nitrate solution with the saturated water absorption capacity is dripped into an unmodified zinc-aluminum catalyst, the loading capacity of iron is enabled to reach 5%, the ferric nitrate solution is placed under the condition that the temperature of an ultrasonic pool is 40 ℃ for 2 hours, drying is carried out in a postoven at the temperature of 110 ℃ for 12 hours, and roasting is carried out in a muffle furnace at the temperature of 400 ℃ for 4 hours, so that the Fe modified zinc-aluminum catalyst with the loading capacity of 5% is obtained. The appearance of the modified zinc-aluminum catalyst is reddish brown powder.

Weighing 5g of commercial HZSM-5 molecular sieve, dripping deionized water into the HZSM-5 molecular sieve, and when the HZSM-5 absorbs water until the saturated surface is fully wet and bonded, wherein the amount of the dripped water is the saturated water absorption capacity of the zinc-aluminum catalyst. According to the saturated water absorption capacity, niobium nitrate solution with a certain mass concentration is prepared by using niobium nitrate and deionized water, and the niobium nitrate solution with the saturated water absorption capacity is dripped into a commercial HZSM-5 molecular sieve catalyst, so that the load capacity of niobium element reaches 3%. In the roomAnd standing at the temperature for 10h, drying the obtained product in a drying oven at 110 ℃ for 12h, and roasting in a muffle furnace at 550 ℃ for 5h to obtain the Nb modified HZSM-5 molecular sieve. The appearance of the catalyst is white powder, the Si/Al molar ratio of the catalyst to the catalyst is 50, and the pore volume is 0.597cm ³ Per g, BET specific surface area 397.9m ² In terms of a/g, the mean pore diameter is 6.01 nm.

The compounding method comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7, also known as synthesis gas) is heated to 180 ℃ by a preheater and enters a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 360 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube, and then a series reaction of methanol synthesis and aromatization is carried out, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water, aliphatic hydrocarbon, various aromatic hydrocarbons including a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

Example 5

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; add solution B stepwise using peristaltic pumpSolution a, until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles are white powder in appearance, show a layered petal-shaped structure appearance under an electron microscope, and have the BET specific surface area of 135.9m ² Per g, pore volume of 0.283cm ³ In terms of a/g, the mean pore diameter is 8.35 nm.

Weighing 5g of porous zinc-aluminum composite particles, dropwise adding deionized water into the porous zinc-aluminum composite particles, and when the porous zinc-aluminum composite particles absorb water until the saturated surfaces are fully wet and bonded, wherein the amount of the dropwise added water is the saturated water absorption amount of the porous zinc-aluminum composite particles. According to the saturated water absorption capacity, a manganese nitrate solution with a certain mass concentration is prepared by using a copper nitrate solution and deionized water, the copper nitrate solution with the saturated water absorption capacity is dripped into unmodified porous zinc-aluminum composite particles, the loading capacity of copper elements reaches 10%, the particles are placed in an ultrasonic pool at the temperature of 40 ℃ for 2 hours, dried in a postoven at the temperature of 110 ℃ for 12 hours, and roasted in a muffle furnace at the temperature of 400 ℃ for 4 hours, so that the Cu modified zinc-aluminum catalyst with the loading capacity of 10% is obtained. The appearance of the modified zinc-aluminum catalyst is black powder.

Weighing 5g of commercial HZSM-5 molecular sieve, dripping deionized water into the HZSM-5 molecular sieve, and when the HZSM-5 molecular sieve absorbs water until the saturated surface is fully wet and bonded, wherein the amount of the dripped water is the saturated water absorption capacity of the zinc-aluminum catalyst. According to the saturated water absorption capacity, niobium nitrate solution with a certain mass concentration is prepared by using niobium nitrate and deionized water, and the niobium nitrate solution with the saturated water absorption capacity is dripped into a commercial HZSM-5 molecular sieve catalyst, so that the load capacity of niobium element reaches 3%. Standing at room temperature for 10h, drying the obtained product in a drying oven at 110 ℃ for 12h, and roasting in a muffle furnace at 550 ℃ for 5h to obtain the Nb modified HZSM-5 molecular sieve, namely the modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is white powder in appearance, the Si/Al molar ratio of the modified HZSM-5 molecular sieve to the modified HZSM-5 molecular sieve is 50, and the pore volume of the modified HZSM-5 molecular sieve is 0.597cm ³ A BET specific surface area of 397.9m ² In terms of a/g, the mean pore diameter is 6.01 nm.

The compounding method comprises the following steps:

Example 6

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 1.28, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. And drying the obtained product in an oven for 12h, and roasting in a muffle furnace at 400 ℃ for 4h to obtain the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles are white powder in appearance, show a layered petal-shaped structure appearance under an electron microscope, and have the BET specific surface area of 135.9m ² /gPore volume of 0.283cm ³ In terms of a/g, the mean pore diameter is 8.35 nm.

Weighing 5g of porous zinc-aluminum composite particles, dropwise adding deionized water into the porous zinc-aluminum composite particles, and when the porous zinc-aluminum composite particles absorb water until the saturated surfaces are fully wet and bonded, wherein the amount of the dropwise added water is the saturated water absorption amount of the porous zinc-aluminum composite particles. According to the saturated water absorption capacity, a manganese nitrate solution with a certain mass concentration is prepared by using a 50% manganese nitrate solution and deionized water, the manganese nitrate solution with the saturated water absorption capacity is dripped into unmodified zinc-aluminum composite particles, the loading capacity of manganese elements reaches 7%, the particles are placed in an ultrasonic pool at the temperature of 40 ℃ for 2 hours, dried in a postoven at the temperature of 110 ℃ for 12 hours, and roasted in a muffle furnace at the temperature of 400 ℃ for 4 hours, and the Mn modified zinc-aluminum catalyst with the loading capacity of 7% is obtained. The appearance of the modified zinc-aluminum catalyst is brown powder, and the BET specific surface area is 156.3m ² Per g, pore volume of 0.208cm ³ (iv)/g, average pore diameter 5.83 nm.

Weighing 5g of commercial HZSM-5 molecular sieve, dripping deionized water into the HZSM-5 molecular sieve, and when the HZSM-5 molecular sieve absorbs water until the saturated surface is fully wet and bonded, wherein the amount of the dripped water is the saturated water absorption capacity of the zinc-aluminum catalyst. According to the saturated water absorption capacity, niobium nitrate solution with a certain mass concentration is prepared by using niobium nitrate and deionized water, and the niobium nitrate solution with the saturated water absorption capacity is dripped into a commercial HZSM-5 molecular sieve, so that the load capacity of niobium element reaches 3%. Standing at room temperature for 10h, drying the obtained product in a drying oven at 110 ℃ for 12h, and roasting in a muffle furnace at 550 ℃ for 5h to obtain the Nb modified HZSM-5 molecular sieve, namely the modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is white powder with the Si/Al molar ratio of 50 and the pore volume of 0.597cm ³ Per g, BET specific surface area 397.9m ² In terms of a/g, the mean pore diameter is 6.01 nm.

The compounding method comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ ＝31:62:7, also called as synthesis gas) is heated to 180 ℃ by a preheater and enters a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 360 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube to carry out a series reaction of methanol synthesis and aromatization, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water and aliphatic hydrocarbon, various aromatic hydrocarbons comprise a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

Example 7

Commercial ZSM-5 catalyst was used. Commercial molecular sieve parameters: the pore volume is 0.340cm ³ (ii)/g, BET specific surface area of 289m ² In terms of a/g, the mean pore diameter is 4.71nm and the molar ratio of silicon to aluminium is 50.

The evaluation of the catalyst performance comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7, also known as synthesis gas) is heated to 180 ℃ by a preheater and enters a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 420 ℃, the reaction operating pressure is 5.0Mpa, and the airspeed of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube to carry out a series reaction of methanol synthesis and aromatization, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water and aliphatic hydrocarbon, various aromatic hydrocarbons comprise a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

Example 8

mixing zinc nitrate, aluminum nitrate, oxalic acid and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate to oxalic acid is 1: 3: 4.48, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the porous zinc-aluminum composite particles. The porous zinc-aluminum composite particles were white powders in appearance.

Commercial ZSM-5 molecular sieves were used. Parameters of commercial ZSM-5 molecular sieves: the pore volume is 0.340cm ³ (ii)/g, BET specific surface area of 289m ² In terms of a/g, the mean pore diameter is 4.71nm and the molar ratio of silicon to aluminium is 50.

The evaluation of the catalyst performance comprises the following steps:

Comparative example 1

Comparative example a method for preparing a precipitated zinc-aluminium catalyst comprises the steps of:

mixing zinc nitrate, aluminum nitrate and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate is 1: 3, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the zinc-aluminum catalyst. The catalyst had the appearance of a white powder and a BET specific surface area of 56.02m ² Per g, pore volume of 0.19cm ³ In terms of/g, the mean pore diameter is 14.68 nm.

Commercial ZSM-5 molecular sieves were used. Parameters of commercial ZSM-5 molecular sieves: the pore volume is 0.340cm ³ (ii)/g, BET specific surface area of 289m ² Per g, mean pore diameter of 4.71nm, Si/Al molThe ratio is 50.

The evaluation of the catalyst performance comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7) was heated to 180 ℃ by a preheater and fed into a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 360 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube to carry out a series reaction of methanol synthesis and aromatization, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water and aliphatic hydrocarbon, various aromatic hydrocarbons comprise a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

Comparative example 2

Comparative example preparation method of zinc-aluminium catalyst by precipitation method comprises the following steps:

mixing zinc nitrate, aluminum nitrate and deionized water to prepare a solution A, and placing the solution A in a water bath at 80 ℃. Mixing sodium carbonate and deionized water to prepare 0.1M solution B; the molar ratio of zinc nitrate to aluminum nitrate is 1:1, adding 300ml of deionized water per 0.045mol of nitrate; solution B was added stepwise to solution a using a peristaltic pump until the solution pH was 8, while maintaining stirring and 70 ℃. Then, the aging and stirring are continued for 1h, and the mixture is filtered and washed twice by suction and washed by 300ml of deionized water each time. The obtained product is dried in an oven for 12 hours and is put into a muffle furnace for roasting at 400 ℃ for 4 hours. Obtaining the zinc-aluminum catalyst. The catalyst had the appearance of a white powder and a BET specific surface area of 36.02m ² Per g, pore volume of 0.17cm ³ In terms of/g, the mean pore diameter is 14.22 nm.

Commercial ZSM-5 molecular sieves were used. Parameters of commercial ZSM-5 molecular sieves: the pore volume is 0.340cm ³ (ii)/g, BET specific surface area of 289m ² Per g, pingThe average pore diameter is 4.71nm, and the silicon-aluminum ratio is 50.

The evaluation of the catalyst performance comprises the following steps:

raw material gas (volume ratio CO: H) ₂ ：N ₂ 31:62:7) was heated to 180 ℃ by a preheater and fed into a fixed bed reactor. Pure hydrogen is used in the catalyst reduction process, the reduction time is 4h, and the fixed bed operation temperature is 400 ℃. The operating temperature of the catalyst in the reaction process is 360 ℃, the reaction operating pressure is 4.0Mpa, and the space velocity of the raw material of the synthesis gas is controlled at 900 mL.h ^-1 ·gcat ^-1 (ii) a The raw material is fully contacted with a catalyst in a reaction tube, and then a series reaction of methanol synthesis and aromatization is carried out, the reaction product is subjected to gas-liquid separation, a liquid-phase product contains trace methanol, water, aliphatic hydrocarbon, various aromatic hydrocarbons including a target product durene, and a gas-phase product contains nitrogen, carbon monoxide, low-carbon alkane, low-carbon olefin and the like.

TABLE 2

As can be seen from Table 2, CO Conv. represents the conversion of aliphatic hydrocarbon, C ₅₊ Is aliphatic hydrocarbon, BTX is benzene, toluene, xylene, C ₉ Is methyl ethyl benzene, trimethyl benzene, C ₁₀₊ Is tetramethylbenzene and aromatic hydrocarbons with carbon number above, and the rest is classified as other.

As can be seen from Table 2, examples 1-6 evaluate the performance of the catalysts for different amounts of metal impregnation, with the reaction product of example 6 having the best results: the COConv. was 58.95%, and the selectivity to tetramethylbenzene was 46.71%. In examples 1, 2 and 6, metal Mn is adopted for modification, and 7% Mn modified zinc aluminum shows the best reaction activity in experiments and has better tetramethylbenzene selectivity. Examples 4, 5 use other metal impregnations, Fe impregnation having a higher selectivity to light aromatics and Cu impregnation having a high selectivity to heavy aromatics at low conversion. In examples 3, 7 and 8, the porous zinc-aluminum catalyst is not modified, and most of aromatic hydrocarbon products are concentrated in trimethylbenzene. From example 7 it is seen that the catalyst achieves a higher conversion but a higher gas phase selectivity at 420 ℃. Therefore, the zinc-aluminum catalyst (figure 1) with the multi-layer petal structure is prepared by a sol precipitation method, and the characteristics of high specific surface area and high pore volume greatly improve the reaction activity and the modifiability of the catalyst. The catalyst performance can be adjusted by adopting active metal impregnation, the effective control on the reaction conversion rate is realized, the distribution of aromatic hydrocarbon products is selected in a targeted manner, the highest CO conversion rate can reach 58.95% by using a 7% Mn modified zinc-aluminum catalyst and a 3% Nb modified commercial HZSM-5 molecular sieve, the aromatic hydrocarbon products are concentrated in the generation of heavy aromatic hydrocarbon, particularly, the selectivity of tetramethylbenzene is good, and the selectivity of tetramethylbenzene can reach 46.71%. The zinc-aluminum catalyst main body adopts zinc nitrate and aluminum nitrate as raw materials, the modified active metal has less use ratio and low price, and the zinc-aluminum catalyst has good industrial application prospect.

The heavy aromatic hydrocarbon product is obtained by the synergistic effect of aromatization and alkylation reactions in the optimized reaction through catalyst design and modification, and has higher production and application values. The above embodiment provides the preferred operating conditions of the zinc-aluminum series catalyst and the HZSM-5 molecular sieve composite catalyst for the one-step preparation of aromatic hydrocarbons from synthesis gas, and oil phase products with different aromatic hydrocarbon distributions can be effectively obtained under the provided reaction conditions.

The present application is described in detail above, and the principles and embodiments of the present application are described herein by using specific examples, which are only used to help understand the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A composite catalyst, comprising:

2. The composite catalyst according to claim 1, wherein the first metal particles are any one of iron, copper, chromium or manganese; and/or the presence of a gas in the gas,

the second metal particles are any one of copper, zinc or niobium.

3. The composite catalyst according to claim 1, wherein the mass ratio of the first metal particles to the porous zinc-aluminum composite particles is (2:100) - (17: 100); and/or the presence of a gas in the gas,

the mass ratio of the second metal particles to the HZSM-5 molecular sieve is (1:100) - (11: 100).

4. The composite catalyst of claim 1, wherein the mass ratio of the modified zinc-aluminum catalyst to the modified HZSM-5 molecular sieve is 1 (0.5-5).

5. The composite catalyst according to claim 1, wherein the porous zinc-aluminum composite particles have a specific surface area of 70m ² /g-250m ² Per g, pore volume of 0.10cm ³ /g-0.45cm ³ (ii) a/g, and/or,

the microscopic appearance of the porous zinc-aluminum composite particles is in a layered petal structure.

6. Composite catalysis according to claim 1The agent is characterized in that the specific surface area of the modified zinc-aluminum catalyst is 125m ² /g-300m ² Per g, pore volume of 0.10cm ³ /g-0.25cm ³ /g。

7. A method of preparing a composite catalyst comprising:

8. The preparation method of the composite catalyst for preparing heavy aromatic hydrocarbon from synthesis gas according to claim 7, wherein the modified zinc-aluminum catalyst and the modified HZSM-5 molecular sieve are mixed according to the mass ratio of 1 (0.5-5).

9. The preparation method of the composite catalyst according to claim 7, wherein the porous zinc-aluminum composite particles are prepared by the following steps:

mixing sodium salt and deionized water to prepare 0.1-1.0M solution B;

10. The method for preparing the composite catalyst according to claim 7, wherein the impregnation amount of the first metal particles is 2 to 15% by mass of the porous zinc-aluminum composite particles; and/or the presence of a gas in the gas,

the impregnation amount of the second metal particles is 1-10% of the mass of the HZSM-5 molecular sieve.

11. Use of the composite catalyst of any one of claims 1 to 6 for the preparation of heavy aromatics from synthesis gas; or the composite catalyst prepared by the preparation method of any one of claims 7 to 10 is used for preparing heavy aromatic hydrocarbon.

12. The preparation method of the heavy aromatic hydrocarbon is characterized by comprising the following steps:

the synthesis gas is used as raw material, and the CO and H in the synthesis gas are catalyzed by the composite catalyst as claimed in any one of claims 1 to 6 ₂ Generating methanol, then carrying out in-situ contact on the generated methanol and a modified HZSM-5 molecular sieve catalyst to carry out aromatization reaction to generate aromatic compounds, and carrying out alkylation reaction outside a pore passage of the modified HZSM-5 molecular sieve to obtain a reaction product;