A catalyst with high mesoporous rate for syngas to olefin, preparation method and application

Abstract

The application provides a high mesopore ratio catalyst for synthesizing olefins from synthesis gas, a preparation method and application, and the catalyst comprises: an active component, an alkaline auxiliary agent and a carbon nanotube-graphene hybrid, wherein the active component and the alkaline auxiliary agent are uniformly dispersed in the inside and the surface of the catalyst, and the mesopore ratio of the catalyst is 30%-60%. Since the catalyst contains the carbon nanotube-graphene hybrid, the heat transfer effect is strengthened, the heat inside the catalyst can be effectively conducted to the outside, the potential internal high temperature is eliminated, the temperature difference between the inside and the outside of the catalyst is reduced to within 0.5 DEG C, the operation life of the catalyst is improved, and the time of high olefin selectivity is prolonged. In addition, the carbon nanotube has the advantage of a large aspect ratio, the carbon nanotube existing in the catalyst can effectively wind the active phase particles, the overall strength of the catalyst can be significantly improved, and the abrasion rate of the catalyst under a large flow rate is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts for preparing light hydrocarbons from synthesis gas and preparation techniques, and in particular to a high mesopore ratio catalyst for preparing olefins from synthesis gas, a preparation method and application. BACKGROUND

[0002] Preparation of olefins from synthesis gas by one-step method is a new emerging catalytic process, and is the latest technology and industrial direction at home and abroad. Its main advantage lies in that synthesis gas can be manufactured from coal, natural gas, biomass, diesel and other hydrocarbons. The one-step method for preparing olefins omits the methanol synthesis reactor, the high-energy consumption methanol refining unit and the large-scale reactor for synthesizing olefins from methanol, so that the highest temperature point and the highest pressure point of the process are significantly reduced, and the process has the development potential of short flow, low consumption, low investment and good intrinsic safety.

[0003] Analysis of the reaction process of preparation of olefins from synthesis gas by one-step method shows that the reaction process couples the two processes of preparation of methanol from synthesis gas and preparation of olefins from methanol. Therefore, the heat release of the reaction is very large. Moreover, the whole process is operated at high pressure. Therefore, more fixed bed forms are selected for preparation of olefins. However, traditional fixed bed catalysts, such as composite catalysts combining metal oxides and molecular sieves, and metal supported catalysts (active components include carbides, metals or metal oxides), have the phenomenon that the internal temperature of the catalyst is significantly higher than the temperature of the outer surface of the catalyst or the temperature of the gas phase main body of the bed. Under the premise of multifunctional integration of the catalyst, the absolutely high internal temperature and the internal-external temperature difference are not conducive to the long-term stable use of the catalyst. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application provides a catalyst structure with high mesopore ratio formed by loading active components and basic adjuvants on carbon nanotube-graphene hybrid, which makes use of the high mass transfer performance of carbon nanotube-graphene hybrid to rapidly conduct the internal temperature of the catalyst out, realizes the relative uniformity of the internal and external temperatures, and prolongs the high olefin selectivity action time and service life of the catalyst.

[0005] The specific application content is as follows:

[0006] In a first aspect, the present application provides a catalyst with high mesopore ratio for preparing olefins from synthesis gas, which comprises: active components, basic adjuvants and carbon nanotube-graphene hybrid;

[0007] The active components comprise one or more combinations of carbonized iron, carbonized molybdenum, carbonized cobalt, gold, copper, zinc, iron, chromium and ferric oxide, and the mass percentage of the active components in the catalyst is 50 %-65 %;

[0008] The basic auxiliary agent is a combination of one or more of sodium type, potassium type, calcium type and magnesium type oxygen-containing compounds, and the mass percentage of the basic auxiliary agent in the catalyst is 3%-20%;

[0009] The mass percentage of the carbon nanotube-graphene hybrid in the catalyst is 25%-47%;

[0010] The mesoporous rate of the catalyst is 30%-60%.

[0011] Optionally, in the carbon nanotube-graphene hybrid, the diameter of the carbon nanotube is 0.5-5 nm, and the number of layers of the graphene is 1-4 layers.

[0012] The volume ratio of the graphene to the carbon nanotube is 1:10-10:1.

[0013] The graphene has through holes with a size of 0.5-2 nm, and the area ratio of the through holes to the graphene is 1-3% (template preparation method, the template contains holes, and the specific surface area is large).

[0014] Optionally, the active component consists of 60-65% of iron carbide, 1-5% of chromium and 30-35% of magnetite, in terms of the mass percentage of the active component.

[0015] The mass percentage of the active component in the catalyst is 55-60%.

[0016] Optionally, the particle size of the active component is 2-12 nm.

[0017] Optionally, the basic auxiliary agent is a combination of one or two of sodium nitrate, potassium nitrate, magnesium nitrate, sodium bicarbonate, basic calcium carbonate, potassium hydroxide, magnesium hydroxide and calcium hydroxide.

[0018] In a second aspect, the present application provides a preparation method of the catalyst for synthesizing gas into olefins as described in the first aspect, and the preparation method comprises:

[0019] The active component and the carbon nanotube-graphene hybrid are added into a basic auxiliary agent precursor solution, stirred at 25-50°C for 2-10 hours, and then heated to 80-120°C for continuous stirring until the viscosity of the slurry reaches 1000-2000 mPa·S;

[0020] The slurry is formed into a strip with a diameter of 2-6 mm through extrusion, and the strip is transferred to a 350-450°C environment for calcination for 1-24 hours, and the catalyst for synthesizing gas into olefins is obtained after cooling.

[0021] Optionally, the basic auxiliary agent precursor solution is prepared by dissolving the basic auxiliary agent in deionized water.

[0022] In a third aspect, the present application provides an application of the catalyst for synthesizing olefins from synthesis gas according to the first aspect, comprising:

[0023] loading the catalyst into a reactor, and introducing a mixed gas of hydrogen and carbon monoxide with a molar ratio of 0.8:1-2:1 into the reactor;

[0024] under preset reaction conditions, the mixed gas reacts under the action of the catalyst to obtain olefins.

[0025] Optionally, the preset reaction conditions are:

[0026] the gas pressure in the reactor is 2-4 MPa;

[0027] the temperature in the reactor is 280-400 ℃;

[0028] the mass space velocity of the catalyst in the reactor is 1-10 h -1 .

[0029] Optionally, when the conversion rate of the carbon monoxide is 65 %-95 %, the selectivity of the olefins is 75 %-90 %.

[0030] Optionally, the reactor used is an axial fixed bed or a radial fixed bed.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] The catalyst for synthesizing olefins from synthesis gas with high mesopore rate provided by the present application has a composition comprising active components, alkaline adjuvants and carbon nanotube-graphene hybrid. The active components and alkaline adjuvants are dispersed in the interior and surface of the catalyst structure, and have the advantage of large amount of active component support, which can adapt to larger operating space velocity and improve the production intensity of the reactor.

[0033] In addition, since the catalyst contains 25 %-47 % carbon nanotube-graphene hybrid, the heat transfer effect is strengthened, the heat inside the catalyst can be effectively conducted to the outside, the potential internal high temperature is eliminated, the temperature difference between the inside and outside of the catalyst is reduced to within 0.5 ℃, the operation life of the catalyst is improved, and the time of high olefin selectivity is prolonged. Further, since the carbon nanotube has the advantage of large aspect ratio, the carbon nanotube existing in the catalyst can effectively wind the active phase particles, which can significantly improve the overall strength of the catalyst and reduce the abrasion rate of the catalyst under large flow rate. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0035] Figure 1 A flow chart of a preparation method of a catalyst for synthesis gas to olefin provided by the embodiment of the present application is shown.

[0036] Figure 2 A flow chart of an application of the catalyst for synthesis gas to olefin provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, any person under the inspiration of the present application or combining the present application with other prior art features can obtain any product same or similar to the present application, which falls within the protection scope of the present application. In addition, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0038] The specific experimental steps or conditions not mentioned in the embodiments can be operated according to the conventional experimental steps described in the prior art in the field. The reagents and other instruments not mentioned by the manufacturer are all conventional reagent products that can be obtained by purchase. In addition, the drawings are only schematic illustrations of the embodiments of the present application, and are not necessarily drawn to scale. The same reference signs in the drawings represent the same or similar parts, and thus repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities.

[0039] The technologies, methods and devices known to those skilled in the relevant art can not be discussed in detail, but under appropriate circumstances, the technologies, methods and devices should be regarded as part of the present application.

[0040] In the description of the present application, it should be understood that the use of the words "first", "second" and the like to qualify elements is only for the convenience of distinguishing the corresponding elements, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0041] Furthermore, the technical features involved in the different embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0042] In a first aspect, the application provides a catalyst with high mesopore rate for synthesizing olefins from syngas, which comprises an active component, an alkaline additive and a carbon nanotube-graphene hybrid, wherein the active component and the alkaline additive are uniformly dispersed in the interior and on the surface of the catalyst structure, and the mesopore rate of the catalyst is 30%-60%.

[0043] In specific implementation, in view of the large specific surface area of graphene in the carbon nanotube-graphene hybrid, the active component and the alkaline additive are mainly dispersed on the graphene, and the carbon nanotube network mainly plays the effect of electrical conductivity and heat conduction. The carbon nanotube-graphene hybrid can be obtained by chemical vapor deposition process or chemical solution method, or can be prepared by mechanical mixing method, which is not limited here. It should be noted that in the carbon nanotube-graphene hybrid, the volume ratio of graphene to carbon nanotube is 1:10-10:1. The graphene itself is graphene containing through holes, the number of layers is 1-4 layers, the area ratio of the through holes is 1-3% of the area of the graphene, and the pore size of the through holes is 0.5-2 nm. The graphene with through holes can be prepared by controlling the density and pore size of the through holes on the template. The diameter of the carbon nanotube is 0.5-5 nm. The mass percentage of the carbon nanotube-graphene hybrid in the catalyst is 25%-47%.

[0044] In specific implementation, the catalyst contains 25%-47% of the carbon nanotube-graphene hybrid, and the rest is the active component and the alkaline additive. The carbon nanotube-graphene hybrid, the active component and the alkaline additive are closely combined, the active component and the alkaline additive are mainly distributed on the surface of the graphene sheet structure, and form a point-like cross-interacting structure with the carbon nanotube network structure. And the graphene surface is distributed with a large number of through holes, creating a large number of mesopores in the catalyst interior, strengthening the heat transfer effect, and can conduct the heat in the catalyst interior to the outside in time, eliminating the potential internal high temperature, reducing the temperature difference between the inside and outside of the catalyst to within 0.5℃, improving the operation life of the catalyst, and prolonging the action time of high olefin selectivity. Further, due to the advantage of large aspect ratio of carbon nanotubes, the carbon nanotubes existing in the catalyst can effectively wrap the active phase particles, which can significantly improve the overall strength of the catalyst and reduce the abrasion rate of the catalyst under large flow rate.

[0045] In specific embodiments, the active component has a particle size of 2-12 nm and accounts for 50-65% of the mass of the catalyst. The active component can be selected from one or more of iron carbide, molybdenum carbide, cobalt carbide, gold, copper, zinc, iron, chromium, and ferric oxide. Preferably, the active component consists of 60-65% iron carbide, 1-5% chromium, and 30-35% ferric oxide, and accounts for 55-60% of the mass of the catalyst.

[0046] In specific embodiments, the basic auxiliary agent accounts for 3-20% of the mass of the catalyst. The basic auxiliary agent can be one or more of sodium, potassium, calcium, and magnesium type oxygen-containing compounds. Preferably, the basic auxiliary agent is one or a combination of two of sodium nitrate, potassium nitrate, magnesium nitrate, sodium bicarbonate, basic calcium carbonate, potassium hydroxide, magnesium hydroxide, and calcium hydroxide.

[0047] In a second aspect, the present application provides a method for preparing a catalyst for the synthesis of olefins from synthesis gas, Figure 1 A flow chart of the method for preparing a catalyst for the synthesis of olefins from synthesis gas according to an embodiment of the present application is shown in FIG. 1. Figure 1 As shown in FIG. 1, the method for preparing a catalyst for the synthesis of olefins from synthesis gas includes the following steps:

[0048] S1, adding the active component and the carbon nanotube-graphene hybrid to the basic auxiliary agent precursor solution, stirring at 25-50°C for 2-10 hours, then increasing the temperature to 80-120°C and continuing to stir until the viscosity of the slurry reaches 1000-2000 mPa·S;

[0049] S2, extruding the slurry into a strip with a diameter of 2-6 mm, transferring the strip to an environment at 350-450°C for calcination for 1-24 hours, and obtaining the catalyst for the synthesis of olefins from synthesis gas after cooling.

[0050] In specific embodiments, the active component, the carbon nanotube-graphene hybrid, and the basic auxiliary agent precursor solution are first stirred at 25-50°C until they are fully mixed and uniform, then the temperature is increased to 80-120°C and the stirring is continued to remove water, and after the viscosity of the slurry reaches 1000-2000 mPa·S, the slurry is extruded into a strip and calcined, and the catalyst for the synthesis of olefins from synthesis gas is obtained after cooling. This preparation scheme has the advantages of easy operation and low cost. Furthermore, this preparation scheme does not limit the amount of active component loaded on the carbon nanotube-graphene hybrid, thereby breaking the limitation of the amount of active component loaded on the existing carrier and enabling the preparation of a catalyst for the synthesis of olefins from synthesis gas that is suitable for a larger operating space velocity.

[0051] In some embodiments, the basic auxiliary agent precursor solution is prepared by dissolving a basic auxiliary agent in deionized water.

[0052] In a third aspect, the present application provides a use of the catalyst for synthesizing olefins from synthesis gas according to the first aspect, Figure 2 A flow chart of the use of the catalyst for synthesizing olefins from synthesis gas provided by the present application is shown in FIG. 2, which comprises the following steps: Figure 2

[0053] S21, loading the catalyst into a reactor and introducing a mixed gas of hydrogen and carbon monoxide with a molar ratio of 0.8:1-2:1 into the reactor;

[0054] S22, under preset reaction conditions, the mixed gas reacts under the action of the catalyst to obtain olefins.

[0055] In a specific implementation, the present application uses an axial fixed bed or a radial fixed bed as a reactor for synthesizing olefins from synthesis gas, loads the catalyst and sets the preset reaction conditions as follows: the gas pressure in the reactor is 2-4 MPa; the temperature in the reactor is 280-400 ℃; the mass space velocity of the catalyst in the reactor is 1-10 h -1 Then the mixed gas of hydrogen and carbon monoxide is introduced to prepare olefins, and when the conversion rate of carbon monoxide is 65 %-95 %, the selectivity of olefins is 75 %-90 %.

[0056] In order for those skilled in the art to more clearly understand the present application, the following examples are used to illustrate the high mesopore ratio catalyst for synthesizing olefins from synthesis gas, the preparation method and the use thereof.

[0057] Example 1

[0058] The active component (90 % of carbonized iron, 10 % of zinc, particle size of 2-5 nm) and the carbon nanotube-graphene hybrid (the diameter of the carbon nanotube is 0.5-5 nm, the number of layers of the graphene is 1-4 layers, the volume ratio of the graphene to the carbon nanotube is 1:10, there are 0.5-2 nm through holes on the graphene, and the area ratio of the through holes is 1 % of the area of the graphene) are added into a previously prepared alkaline additive precursor solution (sodium nitrate, concentration of 1.2 mol / L) to be stirred at 50 ℃ for 2 hours, and then the temperature is increased to 90 ℃ for continuous stirring until the viscosity reaches 1600 mPa·S. Then the strip-shaped material with a diameter of 2 mm is formed by extruding, and is calcined at 380 ℃ for 12 hours.

[0059] The strip-shaped material is subjected to cooling treatment to obtain the catalyst for synthesizing olefins from synthesis gas (the proportion of the active component is 63 %; the proportion of the alkaline additive is 10 %; the proportion of the carbon nanotube-graphene hybrid is 27 %.

[0060] ​The particles of the active component and the basic promoter are mainly dispersed on the surface of the graphene; the carbon nanotubes form a cross-interconnected contact structure with the active component and the basic promoter in a network structure, and the catalyst is stored in a dry and sealed condition. The mesopore proportion of the catalyst is 30%.

[0061] The catalyst is loaded into an axial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 0.8:1 is introduced; the pressure is 2 MPa; the temperature is 350 ℃; the catalyst mass space velocity is 1 h -1 Under the conditions, the olefin synthesis reaction is carried out. In the process of preparing the olefin, when the carbon monoxide conversion rate is 70%, the selectivity of the olefin is 75%.

[0062] Example 2

[0063] The active component (50% molybdenum carbide, 50% cobalt carbide, particle size 2 nm) and the carbon nanotube-graphene hybrid (the diameter of the carbon nanotube is 0.5-5 nm, the number of layers of the graphene is 1-4 layers, the volume ratio of the graphene to the carbon nanotube is 10:1, and the graphene has a through hole of 0.5-2 nm, and the area ratio of the through hole to the graphene is 3%) are added into a previously prepared basic promoter precursor solution (potassium nitrate; concentration 0.1 mol / L) and stirred at 25 ℃ for 10 hours, and then heated to 120 ℃ for continuous stirring until the viscosity reaches 1000 mPaS, and then formed into a strip with a diameter of 5 mm by extrusion, and calcined at 450 ℃ for 1 hour.

[0064] The strip is cooled to obtain a catalyst for preparing olefin from synthesis gas (the proportion of the active component is 65%; the proportion of the basic promoter is 10%; the proportion of the carbon nanotube-graphene hybrid is 25%; the particles of the active component and the basic promoter are mainly dispersed on the surface of the graphene; the carbon nanotubes form a cross-interconnected contact structure with the active component and the basic promoter in a network structure), and the catalyst is stored in a dry and sealed condition. The mesopore proportion of the catalyst is 30%.

[0065] The catalyst is loaded into a radial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 2:1 is introduced; the pressure is 4 MPa; the temperature is 280 ℃; the catalyst mass space velocity is 6 h -1 Under the conditions, the olefin synthesis reaction is carried out. In the process of preparing the olefin, when the carbon monoxide conversion rate is 95%, the selectivity of the olefin is 90%.

[0066] Example 3

[0067] The active component (40% of carbonized iron, 2% of copper, 5% of zinc, 53% of magnetite with a particle size of 2-8 nm) and carbon nanotubes (the diameter of the carbon nanotubes is 0.5-2 nm, the number of layers of graphene is 1-2 layers. The volume ratio of graphene to carbon nanotubes is 1:5. There are through holes of 0.5-0.7 nm on the graphene, and the area ratio of the through holes is 2% of the area of the graphene.) are added into a previously prepared basic auxiliary precursor solution (sodium bicarbonate, basic calcium carbonate; the concentration is 0.8 mol / L) to stir at 45 ℃ for 3 hours, and then the temperature is increased to 105 ℃ for continuous stirring until the viscosity reaches 1300 mPaS. Then, the strip-shaped material with a diameter of 3 mm is formed by extruding, and is calcined at 360 ℃ for 20 hours.

[0068] The strip-shaped material is subjected to cooling treatment to obtain a catalyst for preparing olefins from synthesis gas (the proportion of the active component is 55%; the proportion of the basic auxiliary is 15%; the proportion of the carbon nanotube-graphene hybrid is 30%; the particles of the active substance and the basic auxiliary are mainly dispersed on the surface of the graphene; the carbon nanotubes form a cross-interconnected contact structure with the active component and the basic auxiliary in a network structure), and the catalyst is stored in a dry and sealed condition. The proportion of mesopores of the catalyst is 45%.

[0069] The catalyst is loaded into an axial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 1.6:1 is introduced; the pressure is 2.4 MPa; the temperature is 300 ℃; the mass space velocity of the catalyst is 10 h -1 Under the conditions, the olefin synthesis reaction is carried out. In the process of preparing olefins, when the conversion rate of carbon monoxide is 83%, the selectivity of the olefins is 78%.

[0070] Example 4

[0071] The active component (17% of molybdenum carbide, 0.03% of gold, 59.97% of iron carbide, 13% of magnetite with a particle size of 3-8 nm) and a carbon nanotube-graphene hybrid (the diameter of the carbon nanotubes is 3-5 nm, the number of layers of graphene is 2-4 layers. The volume ratio of graphene to carbon nanotubes is 5:1. There are through holes of 0.5-1 nm on the graphene, and the area ratio of the through holes is 3% of the area of the graphene.) are added into a previously prepared basic auxiliary precursor solution (potassium hydroxide, magnesium hydroxide; the concentration is 1.0 mol / L) to stir at 40 ℃ for 3 hours, and then the temperature is increased to 110 ℃ for continuous stirring until the viscosity reaches 1200 mPa·S. Then, the hollow strip-shaped material with a diameter of 6 mm (the hollow diameter is 1.5 mm) is formed by extruding, and is calcined at 350 ℃ for 12 hours.

[0072] The strip is cooled to obtain a catalyst for preparing olefins from synthesis gas (the active component accounts for 65%; the basic adjuvant accounts for 8%; the carbon nanotube-graphene hybrid accounts for 37%; the particles of the active substance and the basic adjuvant are mainly dispersed on the surface of graphene; the carbon nanotubes form a cross-interconnected contact structure with the active component and the basic adjuvant in a network structure), and the catalyst is stored in a dry and sealed condition. The mesopore of the catalyst accounts for 40%.

[0073] The catalyst is loaded into a radial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 1.2:1 is introduced into the reactor; under the conditions of a pressure of 2.6 MPa, a temperature of 320 ℃, and a catalyst mass space velocity of 10 h -1 The process of preparing olefins is carried out. When the conversion rate of carbon monoxide is 65%, the selectivity of the olefins is 82%.

[0074] Example 5

[0075] The active component (65% carbonized iron, 30% ferroferric oxide, 5% chromium, particle size of 12-20 nm) and the carbon nanotube-graphene hybrid (the diameter of the carbon nanotube is 0.5-5 nm, the number of layers of graphene is 1 layer, the volume ratio of graphene to carbon nanotube is 3:1, graphene has a through hole of 0.5-1.2 nm, and the area ratio of the through hole to graphene is 1.5%) are added into a previously prepared basic adjuvant precursor solution (sodium nitrate, calcium hydroxide; concentration of 0.8 mol / L) to stir at 30 ℃ for 4 hours, and then the temperature is increased to 96 ℃ for continuous stirring until the viscosity reaches 2000 mPa·S. Then, the strip with a diameter of 4 mm is formed by extrusion, and is calcined at 370 ℃ for 24 hours.

[0076] The strip is cooled to obtain a catalyst for preparing olefins from synthesis gas (the active component accounts for 65%; the basic adjuvant accounts for 8%; the carbon nanotube-graphene hybrid accounts for 37%; the particles of the active substance and the basic adjuvant are mainly dispersed on the surface of graphene; the carbon nanotubes form a cross-interconnected contact structure with the active component and the basic adjuvant in a network structure), and the catalyst is stored in a dry and sealed condition. The mesopore of the catalyst accounts for 40%.

[0077] The catalyst is loaded into an axial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 1.6:1 is introduced; under the conditions of a pressure of 3 MPa, a reaction temperature of 360 ℃, and a catalyst mass space velocity of 5 h -1The olefin synthesis reaction is carried out under the conditions that the molar ratio of hydrogen to carbon monoxide is 1.4:1, the pressure is 2.5 MPa, the reaction temperature is 400 ℃, and the mass space velocity of the catalyst is 2.5 h

[0078] Example 6

[0079] The active component (55% of carburized iron, 20% of carburized cobalt, 25% of carburized molybdenum, particle size of 6-10 nm) and the carbon nanotube-graphene hybrid (the diameter of the carbon nanotube is 0.5-3 nm, the number of layers of the graphene is 1-3 layers, the volume ratio of the graphene to the carbon nanotube is 1:1, and there are 0.7-1.5 nm through holes on the graphene, and the area ratio of the through holes to the graphene is 1.6%) are added into the previously prepared basic auxiliary precursor solution (magnesium nitrate, sodium nitrate, concentration of 0.6 mol / L) to be stirred at 28 ℃ for 3 hours, and then the temperature is increased to 100 ℃ for continuous stirring until the viscosity reaches 1500 mPa·S, and then the extruded strip with a diameter of 4.5 mm (hollow diameter of 1 mm) is formed and calcined at 350 ℃ for 10 hours.

[0080] The strip is subjected to cooling treatment to obtain the catalyst for preparing olefin from synthesis gas (the proportion of the active component is 43%, the proportion of the basic auxiliary is 10%, the proportion of the carbon nanotube-graphene hybrid is 47%, the particles of the active substance and the basic auxiliary are mainly dispersed on the surface of the graphene, and the carbon nanotube forms a cross-interconnected contact structure with the active component and the basic auxiliary in a network structure), and the catalyst is stored under dry and sealed conditions. The proportion of mesopores of the catalyst is 50%.

[0081] The catalyst is loaded into an axial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 1.4:1 is introduced; the olefin synthesis reaction is carried out under the conditions that the pressure is 2.5 MPa, the reaction temperature is 400 ℃, and the mass space velocity of the catalyst is 2.5 h -1 The proportion of mesopores of the catalyst is 50%. In the process of preparing the olefin, when the conversion rate of carbon monoxide is 86%, the selectivity of the olefin is 85.2%.

[0082] Comparative Example 1

[0083] The active component (65% of carbonized iron, 30% of ferroferric oxide, 5% of chromium, particle size of 12-20 nm) and the carbon nanotube-graphene hybrid (the diameter of the carbon nanotube is 0.5-5 nm, the number of layers of the graphene is 1 layer, the volume ratio of the graphene to the carbon nanotube is 3:1, and there is no through hole on the graphene) are added into a previously prepared basic auxiliary precursor solution (sodium nitrate, calcium hydroxide, concentration of 0.8 mol / L) and stirred at 30°C for 4 hours, and then heated to 96°C for continuous stirring until the viscosity reaches 2000 mPa·S, and then formed into a strip with a diameter of 4 mm by extruding, and then baked at 370°C for 24 hours;

[0084] The strip is subjected to a cooling process to obtain a catalyst for preparing olefins from synthesis gas (the proportion of the active component is 57%, the proportion of the basic auxiliary agent is 3%, the proportion of the carbon nanotube-graphene hybrid is 40%, the particles of the active substance and the basic auxiliary agent are mainly dispersed on the surface of the graphene, and the carbon nanotube forms a cross-interconnected contact structure with the active component and the basic auxiliary agent in a network structure), and the catalyst is stored in a dry and sealed condition. The proportion of mesopores of the catalyst is 52%.

[0085] The catalyst is loaded into an axial fixed bed reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 1.6:1 is introduced; the pressure is 3 MPa; the reaction temperature is 360°C; the mass space velocity of the catalyst is 5 h -1 Under the conditions, the olefin synthesis reaction is carried out. In the process of preparing the olefin, when the conversion rate of the carbon monoxide is 80%, the selectivity of the olefin is 65%.

[0086] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0087] For method embodiments, some or all of the acts can be performed in succession, in parallel, or in a different order. Additionally, the various steps described herein can be implemented by specialized hardware components, by software, or by a combination of software and hardware. Further, it will be understood that the steps described herein are not necessarily performed in the order described.

[0088] The above provides a detailed description of the high mesopore ratio catalyst for synthesizing gas to olefin, the preparation method and application. The specific examples are applied to the principle and implementation of the present application. The above examples are used to help understand the method and core idea of the present application. Meanwhile, for the general technical personnel in the field, according to the idea of the present application, the specific implementation and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A catalyst for the synthesis of olefins from synthesis gas having a high mesopore rate, characterized in that, The catalyst comprises: an active component, an alkaline auxiliary agent, and a carbon nanotube-graphene hybrid; The active component comprises one or more combinations of iron carbide, molybdenum carbide, cobalt carbide, gold, copper, zinc, iron, chromium, and ferric oxide, and the active component accounts for 50%-65% of the mass percentage of the catalyst; The alkaline auxiliary agent is one or more combinations of sodium, potassium, calcium, and magnesium oxygen compounds, and the alkaline auxiliary agent accounts for 3%-20% of the mass percentage of the catalyst; The carbon nanotube-graphene hybrid accounts for 25%-47% of the mass percentage of the catalyst; The mesopore occupancy of the catalyst is 30%-60%; In the carbon nanotube-graphene hybrid, the diameter of the carbon nanotube is 0.5-5 nm, and the number of layers of the graphene is 1-4 layers; The volume ratio of the graphene to the carbon nanotube is 1:10-10:1; The graphene has a through hole of 0.5-2 nm, and the area of the through hole is 1-3% of the area of the graphene.

2. The catalyst for producing olefin from synthesis gas according to claim 1, wherein The particle size of the active component is 2-12 nm.

3. The catalyst for producing olefin from synthesis gas according to claim 1, wherein The alkaline auxiliary agent is one or two combinations of sodium nitrate, potassium nitrate, magnesium nitrate, sodium bicarbonate, basic calcium carbonate, potassium hydroxide, magnesium hydroxide, and calcium hydroxide.

4. A process for the preparation of a catalyst for the synthesis of olefins from synthesis gas according to any one of claims 1 to 3, characterized in that The preparation method comprises: The active component and the carbon nanotube-graphene hybrid are added to an alkaline auxiliary agent precursor solution, stirred at 25-50°C for 2-10 hours, and then heated to 80-120°C for continuous stirring until the viscosity of the slurry reaches 1000-2000 mPa·S; The slurry is formed into a strip with a diameter of 2-6 mm by extrusion, the strip is transferred to a 350-450°C environment for calcination for 1-24 hours, and the catalyst for preparing olefins from synthesis gas is obtained after cooling.

5. The preparation method according to claim 4, characterized in that, The alkaline auxiliary agent precursor solution is prepared by dissolving the alkaline auxiliary agent in deionized water.

6. Use of a catalyst according to any one of claims 1 to 3 for the synthesis of olefins from synthesis gas, characterized in that, Comprise: The catalyst is loaded into a reactor, and a mixed gas of hydrogen and carbon monoxide with a molar ratio of 0.8:1-2:1 is introduced into the reactor; Under preset reaction conditions, the mixed gas reacts under the action of the catalyst to obtain olefins.

7. Use according to claim 6, characterized in that, The preset reaction conditions are: The gas pressure in the reactor is 2-4 MPa; The temperature in the reactor is 280-400°C; The mass space velocity of the catalyst in the reactor is 1 -10 h -1 .

8. Use according to claim 6, characterized in that, When the conversion rate of the carbon monoxide is 65%-95%, the selectivity of the olefins is 75%-90%.

9. Use according to claim 6, characterized in that, The reactor used is an axial fixed bed or a radial fixed bed.

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