A supported molybdenum carbide catalyst, its preparation method and use

Abstract

The application relates to the technical field of catalytic material preparation, and particularly discloses a supported molybdenum carbide catalyst and a preparation method and application thereof. The preparation method comprises the following steps: dissolving a molybdenum source in ammonia water, adding an organic carbon source, uniformly mixing, and obtaining a precursor solution; adding alumina into the precursor solution, impregnating, drying, and obtaining impregnated alumina; dissolving a metal salt in water to obtain a metal salt solution; adding the impregnated alumina into the metal salt solution, standing, aging, drying, roasting, cooling, and passivating to obtain the supported molybdenum carbide catalyst. The supported molybdenum carbide catalyst provided by the application has the advantages that each active component in the carrier maintains a high dispersion state, the combination of the active component and the carrier is high, the active component is not easy to lose in the catalytic process, the purpose of efficiently activating and converting synthesis gas to low-carbon alcohol under mild conditions is realized through the synergistic effect of the molybdenum carbide and the potassium, iron or cobalt active components, the industrial application prospect is high, and the application has high practical value.

Description

Technical Field

[0001] This invention relates to the field of catalytic material preparation technology, and in particular to a supported molybdenum carbide catalyst, its preparation method, and its application. Background Technology

[0002] Low-carbon alcohols (HAS) are generally defined as alcohols containing two or more carbon atoms, primarily monohydric alcohols with fewer than six carbon atoms. They can be used as fuel additives, lubricants, or pharmaceutical intermediates, and have attracted widespread attention from researchers due to their high economic value. Of particular note is that HAS possess excellent performance while also being environmentally friendly. Direct synthesis of HAS from coal, biomass, shale gas, and syngas extracted from carbon dioxide not only alleviates the current shortage of petroleum resources but also represents one of the most realistic and feasible ways to achieve efficient and clean conversion of coal resources, making it a promising synthetic route.

[0003] The selectivity of the synthesis of lower alcohols from syngas depends primarily on the catalyst type and reaction conditions; therefore, catalyst research is currently a focus of attention. Four main types of catalysts for the synthesis of lower alcohols from syngas have been reported in the literature: copper-based catalysts, FT catalysts, rhodium-based catalysts, and molybdenum-based catalysts. Among these, molybdenum-based catalysts exhibit relatively stable physical properties, good hydrogenation activity, and unique resistance to sulfidation. Furthermore, studies have shown that molybdenum carbide catalysts demonstrate higher selectivity for lower alcohols compared to other molybdenum-based catalysts, making them the most promising catalysts for the synthesis of lower alcohols from syngas.

[0004] The activity and selectivity of molybdenum carbide alone in the production of lower alcohols from syngas are unsatisfactory, requiring modification with multiple components. However, existing methods for preparing multi-component molybdenum carbide catalysts result in poor dispersion of the components and weak bonding between them, leading to poor catalyst activity and stability, thus limiting significant improvements in catalyst activity. Summary of the Invention

[0005] To address the problems of low catalytic activity and stability, and complex preparation methods in existing methods for preparing multi-component molybdenum carbide catalysts, this invention provides a supported molybdenum carbide catalyst, its preparation method, and its applications. By selecting specific carbon sources and modifying molybdenum carbide with potassium, cobalt, and / or iron during the preparation process, the resulting catalyst exhibits excellent activity, selectivity, and stability in the synthesis of lower alcohols from syngas. Furthermore, the preparation cost is low, the operation is simple, and it has significant practical application value.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the embodiments of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a supported molybdenum carbide catalyst, comprising the following steps:

[0008] Step a: Dissolve the molybdenum source in ammonia water to obtain a molybdenum source solution; add an organic carbon source to the molybdenum source solution and mix evenly to obtain a precursor solution; wherein the organic carbon source is at least one of hexamethylenetetramine or N,N-dimethylphenylenediamine;

[0009] Step b: Add aluminum oxide to the precursor solution, impregnate, and dry to obtain impregnated aluminum oxide;

[0010] Step c: Dissolve the metal salt in water to obtain a metal salt solution; add the impregnated alumina to the metal salt solution, allow it to stand and age, and dry to obtain a catalyst precursor; wherein the metal salt includes a first metal salt and a second metal salt, the first metal salt being a potassium salt, and the second metal salt being one or both of an iron salt or a cobalt salt.

[0011] Step d: The catalyst precursor is pulverized, calcined, cooled, and passivated to obtain the supported molybdenum carbide catalyst.

[0012] Compared to existing technologies, the preparation method of the supported molybdenum carbide catalyst provided by this invention employs a stepwise impregnation method. Before loading the Mo source onto the alumina surface, the molybdenum source and a specific organic carbon source are complexed. This not only achieves uniform loading of Mo on the alumina surface, avoiding the problem of Mo agglomeration on the alumina surface, but also achieves molecular-level mixing of Mo and the organic carbon source. This avoids the problem of severe carbon accumulation on the catalyst surface caused by insufficient contact between the carbon source and the molybdenum source during subsequent calcination. At the same time, after the Mo is complexed and impregnated with the specific carbon source, a modified metal salt solution is impregnated. This avoids the reaction of Mo with the modified salt solution to generate byproducts such as ferric molybdate or cobalt molybdate, which would cause problems such as decreased catalyst activity and unstable catalyst activity.

[0013] The preparation method provided by this invention can prepare a multi-component uniformly dispersed supported molybdenum carbide catalyst. Through the synergistic effect of multiple active centers such as Mo, K, Co or Fe, the activity of the catalyst is significantly improved. Moreover, the preparation method of the catalyst is simple and does not require high temperature and high pressure conditions, making it suitable for large-scale industrial preparation and application.

[0014] Preferably, in step a, the molybdenum source is at least one of sodium molybdate, ammonium heptamolybdate, or ammonium tetramolybdate.

[0015] Preferably, in step a, the concentration of molybdenum ions in the molybdenum source solution is 0.1 mol / L to 0.4 mol / L.

[0016] Preferably, in step a, the mass concentration of the ammonia water is 10%-15%.

[0017] Preferably, in step a, the molar ratio of Mo in the organic carbon source to that in the molybdenum source is 7-10:1.

[0018] The preferred organic carbon source can not only be used as a carbon source for calcination and carbonization to obtain carbon, but also complex Mo to improve the mixing degree of molybdenum source and carbon source. Moreover, the chelating force is moderate, which can avoid side reactions between Mo and modified salt solution during subsequent impregnation with modified metal salt solution, ensuring the production of pure phase molybdenum carbide, thereby contributing to a significant improvement in catalytic activity.

[0019] Preferably, in step b, before impregnating the alumina precursor solution, the alumina carrier is further calcined at 450℃-600℃ for 3-5 hours.

[0020] Furthermore, in step b, the particle size of the alumina support is 5μm-20μm.

[0021] Calcination of alumina before impregnation with a molybdenum source can increase the specific surface area of ​​alumina and remove impurities from the alumina carrier, thereby increasing the loading of molybdenum and modified metal elements (such as K, Fe or Co).

[0022] For example, in step a, in order to ensure that the organic carbon source and the molybdenum source solution can be fully mixed, the organic carbon source and the molybdenum source solution can be mixed by ultrasound, heating or magnetic stirring.

[0023] Preferably, in step b, the molar ratio of alumina to Mo in the molybdenum source is 4-6:1.

[0024] Preferably, in step b, the impregnation is ultrasonic impregnation, the impregnation temperature is 20℃-40℃, and the impregnation time is 1h-2h.

[0025] For example, in step b, the drying is carried out by freeze drying, with a drying temperature of -80℃ to 0℃, a vacuum degree of less than 48mTorr, and a drying time of 10h to 20h.

[0026] Preferred drying methods help maintain the structural integrity and valence stability of the multiple components in the catalyst.

[0027] Preferably, in step c, the molar ratio of the first metal salt to the second metal salt is 1:1.5-2.5 based on metal elements; and the concentration of the second metal salt in the metal salt solution is 1.1 mol / L-1.8 mol / L.

[0028] Preferably, in step c, the volume-to-mass ratio of the metal salt solution to aluminum oxide is 1:1.5-3.0, where volume is measured in milliliters and mass in grams.

[0029] Preferably, in step c, the temperature for static aging is 20℃-40℃, and the time is 3h-5h.

[0030] For example, in step c, the drying is carried out by freeze drying, with a drying temperature of -80℃ to 0℃, a vacuum degree of less than 48mTorr, and a drying time of 10h to 20h.

[0031] Preferred impregnation conditions facilitate the uniform loading of modified metals onto the alumina support, and the selection of K, Fe, or Co in synergy with Mo can give the catalyst excellent catalytic activity for the production of lower alcohols from CO / H2 syngas.

[0032] Preferably, in step d, the specific steps of the calcination are as follows: under a hydrogen and nitrogen atmosphere, the temperature is increased to 500℃-600℃ at a rate of 3-5℃ / min, and held for 2h-4h; then under an ethane and argon atmosphere, the temperature is increased to 600℃-800℃ at a rate of 1-2℃ / min, and held for 4h-10h.

[0033] More preferably, the volume content of hydrogen in the above-mentioned roasting atmosphere of hydrogen and nitrogen is 10%-35%.

[0034] More preferably, the volume content of ethane in the above-mentioned calcination atmosphere of ethane and argon is 5%-15%.

[0035] The optimized calcination process, through multi-stage temperature and calcination atmosphere control, facilitates the full carbonization of molybdenum, resulting in a better crystal form of the formed molybdenum carbide. It also helps to maintain a high degree of dispersion of other active components, avoids loss of active components, and reduces the aggregation of molybdenum carbide, thereby improving the catalytic activity of the prepared catalyst.

[0036] Preferably, in step d, the specific passivation step is: passivating the cooled carrier for 4-8 hours under an argon and oxygen atmosphere.

[0037] More preferably, the volume content of oxygen in the above-mentioned argon and oxygen mixture is 1%-10%.

[0038] Furthermore, the flow rate of the mixed gas during the calcination and passivation processes is 75 mL / min-85 mL / min.

[0039] Secondly, the present invention also provides a supported molybdenum carbide catalyst, which is prepared by the method for preparing the supported molybdenum carbide catalyst described in any of the above claims.

[0040] The supported molybdenum carbide catalyst prepared by this invention has excellent catalytic activity, selectivity and stability for the production of lower alcohols from CO / H2 syngas. Moreover, the preparation process is simple, the raw materials are widely available and the cost is low, so it has broad application prospects in the field of syngas-to-low alcohol production.

[0041] Thirdly, the present invention also provides the application of the above-mentioned supported molybdenum carbide catalyst in the preparation of lower alcohols from syngas.

[0042] Fourthly, the present invention also provides a method for producing lower alcohols from syngas, comprising the following steps:

[0043] Silicon carbide particles are added to the top and bottom of the catalyst bed in the reactor, and the middle layer is filled with a mixture of the above-mentioned supported molybdenum carbide catalyst and silicon carbide particles. Syngas is introduced to carry out the reaction and obtain low-carbon alcohols.

[0044] Preferably, the synthesis gas is H2 and CO in a molar ratio of 1-2:1, the reaction temperature is 310℃-330℃, the reaction pressure is 3.0MPa-3.5MPa, and the space velocity is 3800mL·g. cat -1 ·h -1 -4200mL·g cat -1 ·h -1 .

[0045] Furthermore, the silicon carbide particles added above and below the catalyst bed have a particle size of 10-30 mesh.

[0046] Furthermore, the silicon carbide particles used in the mixing with the supported molybdenum carbide catalyst have a particle size of 80-100 mesh.

[0047] Furthermore, the volume of 80-100 mesh silicon carbide particles is three times the mass of the supported molybdenum carbide catalyst, where volume is measured in milliliters and mass in grams.

[0048] The supported molybdenum carbide catalyst provided by this invention maintains a high degree of dispersion of each active component in the support, and the binding force between the active components and the support is high. The active components are not easily lost during the catalytic process. Through the synergistic effect of molybdenum carbide and multiple active components such as potassium, iron or cobalt, the purpose of efficient activation and conversion of syngas to low-carbon alcohols under mild conditions is achieved. It has high prospects for industrial application and has high practical value. Attached Figure Description

[0049] Figure 1 The XRD characterization diagram of the KCo-Mo2C / Al2O3 catalyst prepared in Example 1;

[0050] Figure 2Evaluation data for the KCo-Mo2C / Al2O3 catalyst prepared in Example 1 for the synthesis of lower alcohols from syngas. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0052] To better illustrate the present invention, further examples are provided below.

[0053] The alumina support used in the following examples and comparative examples is a γ-Al2O3 support obtained by high-temperature calcination at 600°C for 4 hours.

[0054] Example 1

[0055] This embodiment provides a method for preparing a supported molybdenum carbide catalyst, comprising the following steps:

[0056] Step 1: Add 2.48g of (NH4)6Mo7O 24 • Add 4H2O to 40mL of 15% ammonia solution, mix well, add 17.72g of hexamethylenetetramine, stir thoroughly to obtain the precursor solution;

[0057] Step 2: Add 6.0g of γ-Al2O3 support to the above precursor solution, impregnate at 30℃ for 1h, and then dry at -20℃ and vacuum degree below 48mTorr for 20h to obtain impregnated alumina;

[0058] Step 3: Dissolve 1.68g Co(NO3)2·6H2O and 0.23g K2CO3 in 4mL of deionized water to obtain a mixed salt solution; add the entire mixed salt solution dropwise onto the alumina-impregnated sample, stirring thoroughly during the process, until all the mixed salt solution is added; allow to stand at 30℃ for 5h for aging, and then dry at -20℃ and a vacuum of 48mTorr or less for 20h to obtain the catalyst precursor;

[0059] Step 4: After grinding the above catalyst precursor into powder, place it in a quartz boat and put it in a tube furnace. Heat the furnace to 500°C at a rate of 4°C / min and hold for 3 hours. The protective gas during this stage is a mixture of hydrogen and nitrogen with a hydrogen content of 20% and a flow rate of 80 mL / min. Then switch the protective gas to a mixture of ethane and argon with an ethane content of 10% and a flow rate of 80 mL / min. Heat the furnace to 600°C at a rate of 1°C / min and hold for 5 hours. Allow the furnace to cool naturally to room temperature. Then switch the furnace to a mixture of argon and oxygen with an oxygen content of 2% and a flow rate of 80 mL / min for 4 hours to obtain the KCo-Mo2C / Al2O3 catalyst.

[0060] The XRD characterization pattern of the KCo-Mo2C / Al2O3 catalyst prepared in this embodiment is as follows: Figure 1 As shown in the XRD pattern, the main phases of the catalyst are Al2O3, Mo2C and Co.

[0061] The BET test results of the KCo-Mo2C / Al2O3 catalyst prepared in this embodiment are shown in Table 1.

[0062] Table 1 BET test results of KCo-Mo2C / Al2O3 catalyst

[0063] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 106.2 0.78 29.3

[0064] The KCo-Mo2C / Al2O3 catalyst prepared in this embodiment was used for the synthesis of lower alcohols from syngas.

[0065] Add 6 mL of 15-mesh silicon carbide particles to both the top and bottom of the catalyst bed. Mix 1 g of KCo-Mo2C / Al2O3 catalyst with 3 mL of 80-mesh silicon carbide particles until homogeneous, then load this mixture into the middle layer of the catalyst bed. Install the reaction tube and check the airtightness of the apparatus. Once it passes the test, introduce synthesis gas. The reaction conditions are: H2 / CO = 2, temperature 320℃, pressure 3.0 MPa, and space velocity 4000 mL·g⁻¹. cat -1 ·h -1 Gas phase products were analyzed by online chromatography, while liquid phase products were analyzed by offline gas chromatography.

[0066] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion rate was 63.6%. Figure 2 As shown, the catalyst exhibits excellent stability during the reaction; the selectivity for total alcohols is 67.6%, C 2+ The alcohol selectivity was 74.3%, and the total alcohol space yield was 364.2 mg / g / h.

[0067] The molar ratio of H2 to CO in the above-mentioned synthesis gas to lower alcohols was changed to 1, while other conditions remained unchanged. The reaction was carried out under these conditions for 80 h, and evaluation data for the catalyst were obtained. The carbon monoxide conversion rate was 59.3%, the total alcohol selectivity was 64.2%, and the C2O conversion rate was [not specified]. 2+ The alcohol selectivity was 69.1%, and the total alcohol space yield was 308.7 mg / g / h.

[0068] Example 2

[0069] This embodiment provides a method for preparing a supported molybdenum carbide catalyst, comprising the following steps:

[0070] Step 1: Add 2.48g of (NH4)6Mo7O 24 · Add 4H2O to 100mL of 13% ammonia solution, mix well, add 14.15g of hexamethylenetetramine, stir thoroughly to obtain the precursor solution;

[0071] Step 2: Add 7.5g of γ-Al2O3 support to the above precursor solution, impregnate at 20℃ for 2h, and then dry at -15℃ and vacuum degree below 48mTorr for 20h to obtain impregnated alumina;

[0072] Step 3: Dissolve 2.05g Fe(NO3)3·9H2O and 0.23g K2CO3 in 4mL of deionized water to obtain a mixed salt solution; add the entire mixed salt solution dropwise onto the impregnated alumina sample, stirring thoroughly during the process, until all the mixed salt solution is added; allow to stand at 20℃ for 5h for aging, and then dry at -15℃ and a vacuum degree below 48mTorr for 20h to obtain the catalyst precursor;

[0073] Step 4: After grinding the above catalyst precursor into powder, place it in a quartz boat and put it in a tube furnace. Heat the furnace to 600°C at a rate of 3°C / min and hold for 2 hours. The protective gas during this stage is a mixture of hydrogen and nitrogen with a hydrogen content of 20% and a flow rate of 80 mL / min. Then switch the protective gas to a mixture of ethane and argon with an ethane content of 10% and a flow rate of 80 mL / min. Heat the furnace to 800°C at a rate of 1°C / min and hold for 5 hours. Allow the furnace to cool naturally to room temperature. Then switch the furnace to a mixture of argon and oxygen with an oxygen content of 2% and a flow rate of 80 mL / min for 4 hours to obtain the KFe-Mo2C / Al2O3 catalyst.

[0074] The BET test results of the KFe-Mo2C / Al2O3 catalyst prepared in this embodiment are shown in Table 2.

[0075] Table 2 BET test results of KFe-Mo2C / Al2O3 catalyst

[0076] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 98.3 0.37 16.1

[0077] The KFe-Mo2C / Al2O3 catalyst prepared in this example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0078] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 84.7%, the total alcohol selectivity was 58.6%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 71.0%, and the total alcohol space yield was 325.2 mg / g / h.

[0079] Example 3

[0080] This embodiment provides a method for preparing a supported molybdenum carbide catalyst, comprising the following steps:

[0081] Step 1: Add 2.48g of (NH4)6Mo7O 24 · Add 4H2O to 60 mL of 12% ammonia solution, mix well, add 19.12 g of N,N-dimethylphenylenediamine, stir thoroughly to obtain the precursor solution;

[0082] Step 2: Add 8.5g of γ-Al2O3 support to the above precursor solution, impregnate at 40℃ for 1h, and then dry at -25℃ and vacuum degree below 48mTorr for 15h to obtain impregnated alumina.

[0083] Step 3: Dissolve 2.41g Co(NO3)2·9H2O and 0.23g K2CO3 in 4mL of deionized water to obtain a mixed salt solution; add the entire mixed salt solution dropwise onto the alumina-impregnated sample, stirring thoroughly during the process until all the mixed salt solution is added; allow to stand at 40℃ for 3h for aging, and then dry at -25℃ and a vacuum degree below 48mTorr for 15h to obtain the catalyst precursor;

[0084] Step 4: After grinding the above catalyst precursor into powder, place it in a quartz boat and put it in a tube furnace. Heat the furnace to 600°C at a rate of 5°C / min and hold for 2 hours. The protective gas during this stage is a mixture of hydrogen and nitrogen with a hydrogen content of 20% and a flow rate of 80 mL / min. Then switch the protective gas to a mixture of ethane and argon with an ethane content of 10% and a flow rate of 80 mL / min. Heat the furnace to 700°C at a rate of 2°C / min and hold for 4 hours. Allow the furnace to cool naturally to room temperature. Then switch the furnace to a mixture of argon and oxygen with an oxygen content of 2% and a flow rate of 80 mL / min for 6 hours to obtain the KCo-Mo2C / Al2O3 catalyst.

[0085] The BET test results of the KCo-Mo2C / Al2O3 catalyst prepared in this embodiment are shown in Table 3.

[0086] Table 3 BET test results of KCo-Mo2C / Al2O3 catalyst

[0087] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 108.6 0.61 22.6

[0088] The KCo-Mo2C / Al2O3 catalyst prepared in this example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0089] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 59.5%, the total alcohol selectivity was 73.4%, and the C1... 2+ The alcohol selectivity was 68.3%, and the total alcohol space yield was 293.8 mg / g / h.

[0090] Example 4

[0091] This embodiment provides a method for preparing a supported molybdenum carbide catalyst, comprising the following steps:

[0092] Step 1: Add 2.48g of (NH4)6Mo7O 24 • Add 4H2O to 36 mL of 10% ammonia solution, mix well, add 16.25 g of hexamethylenetetramine, stir thoroughly to obtain the precursor solution;

[0093] Step 2: Add 7.0g of γ-Al2O3 support to the above precursor solution, impregnate at 30℃ for 1h, and then dry at -30℃ and vacuum degree below 48mTorr for 10h to obtain impregnated alumina;

[0094] Step 3: Dissolve 1.85g Co(NO3)2·9H2O and 0.23g K2CO3 in 4mL of deionized water to obtain a mixed salt solution; add the entire mixed salt solution dropwise onto the alumina-impregnated sample, stirring thoroughly during the process, until all the mixed salt solution is added; allow to stand at 30℃ for 4h for aging, and then dry at -30℃ and a vacuum of 48mTorr or less for 10h to obtain the catalyst precursor;

[0095] Step 4: After grinding the above catalyst precursor into powder, place it in a quartz boat and put it in a tube furnace. Heat the furnace to 600°C at a rate of 3°C / min and hold for 3 hours. The protective gas during this stage is a mixture of hydrogen and nitrogen with a hydrogen content of 20% and a flow rate of 80 mL / min. Then switch the protective gas to a mixture of ethane and argon with an ethane content of 10% and a flow rate of 80 mL / min. Heat the furnace to 650°C at a rate of 1°C / min and hold for 7 hours. Allow the furnace to cool naturally to room temperature. Then switch the furnace to a mixture of argon and oxygen with an oxygen content of 2% and a flow rate of 80 mL / min for 5 hours to obtain the KCo-Mo2C / Al2O3 catalyst.

[0096] The BET test results of the KCo-Mo2C / Al2O3 catalyst prepared in this embodiment are shown in Table 4.

[0097] Table 4 BET test results of KCo-Mo2C / Al2O3 catalyst

[0098] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 103.8 0.77 29.8

[0099] The KFe-Mo2C / Al2O3 catalyst prepared in this example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0100] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 60.9%, the total alcohol selectivity was 61.2%, and the C1... 2+ The alcohol selectivity was 73.5%, and the total alcohol space yield was 298.7 mg / g / h.

[0101] Comparative Example 1

[0102] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that the cobalt nitrate in Example 1 is replaced with an equimolar amount of copper nitrate to obtain the KCu-Mo2C / Al2O3 catalyst.

[0103] The BET test results of the KCu-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 5.

[0104] Table 5 BET test results of KCu-Mo2C / Al2O3 catalyst

[0105] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 107.5 0.74 27.6

[0106] The KCu-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0107] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 25.2%, the total alcohol selectivity was 53.4%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 43.9%, and the total alcohol space yield was 201.5 mg / g / h.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that cobalt nitrate in Example 1 is replaced with an equimolar amount of zinc nitrate to obtain the KZn-Mo2C / Al2O3 catalyst.

[0110] The BET test results of the KZn-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 6.

[0111] Table 6 BET test results of KZn-Mo2C / Al2O3 catalyst

[0112] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 108.9 0.73 27.0

[0113] The KZn-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0114] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 18.6%, the total alcohol selectivity was 42.9%, and the C1... 2+ The alcohol selectivity was 39.6%, and the total alcohol space yield was 183.4 mg / g / h.

[0115] Comparative Example 3

[0116] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 2, except that potassium carbonate is not added, resulting in a Fe-Mo2C / Al2O3 catalyst.

[0117] The BET test results of the Fe-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 7.

[0118] Table 7 BET test results of Fe-Mo2C / Al2O3 catalyst

[0119] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 102.9 0.44 17.2

[0120] The Fe-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0121] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 68.1%, the total alcohol selectivity was 53.9%, and the C1... 2+ The alcohol selectivity was 42.6%, and the total alcohol space yield was 256.6 mg / g / h.

[0122] Comparative Example 4

[0123] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that potassium carbonate is not added, resulting in a Co-Mo2C / Al2O3 catalyst.

[0124] The BET test results of the Co-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 8.

[0125] Table 8 BET test results of Co-Mo2C / Al2O3 catalyst

[0126] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 111.0 0.72 26.0

[0127] The Co-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0128] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 92.5%, the total alcohol selectivity was 45.3%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 26.1%, and the total alcohol space yield was 167.6 mg / g / h.

[0129] Comparative Example 5

[0130] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that cobalt nitrate is not added, resulting in a K-Mo2C / Al2O3 catalyst.

[0131] The BET test results of the K-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 9.

[0132] Table 9 BET test results of K-Mo2C / Al2O3 catalyst

[0133] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 119.0 0.76 25.0

[0134] The K-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0135] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 68.3%, the total alcohol selectivity was 58.6%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 58.1%, and the total alcohol space yield was 284.2 mg / g / h.

[0136] Comparative Example 6

[0137] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that cobalt nitrate in Example 1 is replaced with nickel nitrate to obtain a KNi-Mo2C / Al2O3 catalyst.

[0138] The BET test results of the KNi-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 10.

[0139] Table 10 BET test results of KNi-Mo2C / Al2O3 catalyst

[0140] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 102.0 0.77 26.9

[0141] The KNi-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0142] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 32.9%, the total alcohol selectivity was 48.6%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 38.1%, and the total alcohol space yield was 192.6 mg / g / h.

[0143] Comparative Example 7

[0144] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that the hexamethylenetetramine in Example 1 is replaced with an equal proportion of aniline to obtain the KCo-Mo2C / Al2O3 catalyst.

[0145] The BET test results of the KCo-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 11.

[0146] Table 11 BET test results of KCo-Mo2C / Al2O3 catalyst

[0147] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 104.1 0.81 29.5

[0148] The KCo-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0149] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 42.9%, the total alcohol selectivity was 51.1%, and the C1 ratio was [not specified]. 2+ The alcohol selectivity was 53.9%, and the total alcohol space yield was 245.3 mg / g / h.

[0150] Comparative Example 8

[0151] This comparative example provides a method for preparing a supported molybdenum carbide catalyst. The preparation steps are exactly the same as in Example 1, except that the hexamethylenetetramine in Example 1 is replaced with an equal proportion of citric acid to obtain the KCo-Mo2C / Al2O3 catalyst.

[0152] The BET test results of the KCo-Mo2C / Al2O3 catalyst prepared in this comparative example are shown in Table 12.

[0153] Table 12 BET test results of KCo-Mo2C / Al2O3 catalyst

[0154] <![CDATA[Specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume V BJH (cm 3 ·g -1 )]]> Aperture D (nm) 102.7 0.73 29.4

[0155] The KCo-Mo2C / Al2O3 catalyst prepared in this comparative example was used to synthesize low-carbon alcohols from syngas, and the synthesis conditions were exactly the same as in Example 1.

[0156] The catalyst was evaluated after reacting for 80 hours under these conditions. The carbon monoxide conversion was 20.3%, the total alcohol selectivity was 36.8%, and the C1... 2+ The alcohol selectivity was 14%, and the total alcohol space yield was 103.3 mg / g / h.

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a supported molybdenum carbide catalyst, characterized in that, Includes the following steps: Step a: Dissolve the molybdenum source in ammonia water to obtain a molybdenum source solution; add an organic carbon source to the molybdenum source solution and mix evenly to obtain a precursor solution; wherein the organic carbon source is at least one of hexamethylenetetramine or N,N-dimethylphenylenediamine; Step b: Add aluminum oxide to the precursor solution, impregnate, and dry to obtain impregnated aluminum oxide; Step c: Dissolve the metal salt in water to obtain a metal salt solution; add the impregnated alumina to the metal salt solution, allow it to stand and age, and dry to obtain a catalyst precursor; wherein the metal salt includes a first metal salt and a second metal salt, the first metal salt being a potassium salt, and the second metal salt being one or both of an iron salt or a cobalt salt. Step d: The catalyst precursor is pulverized, calcined, cooled, and passivated to obtain the supported molybdenum carbide catalyst.

2. The method for preparing the supported molybdenum carbide catalyst as described in claim 1, characterized in that, In step a, the molybdenum source is at least one of sodium molybdate, ammonium heptamolybdate, or ammonium tetramolybdate; and / or In step a, the concentration of molybdenum ions in the molybdenum source solution is 0.1 mol / L to 0.4 mol / L; and / or In step a, the mass concentration of the ammonia solution is 10%-15%; and / or In step a, the molar ratio of Mo in the organic carbon source to that in the molybdenum source is 7-10:

1.

3. The method for preparing the supported molybdenum carbide catalyst as described in claim 1, characterized in that, In step b, before the alumina impregnation precursor solution, the alumina carrier is further calcined at 450℃-600℃ for 3-5 hours.

4. The method for preparing the supported molybdenum carbide catalyst as described in claim 1 or 3, characterized in that, In step b, the molar ratio of alumina to Mo in the molybdenum source is 4-6:1; and / or In step b, the impregnation is ultrasonic impregnation, the impregnation temperature is 20℃-40℃, and the impregnation time is 1h-2h.

5. The method for preparing the supported molybdenum carbide catalyst as described in claim 1, characterized in that, In step c, the molar ratio of the first metal salt to the second metal salt, calculated by metal element, is 1:1.5-2.5; the concentration of the second metal salt in the metal salt solution is 1.1 mol / L-1.8 mol / L; and / or In step c, the volume-to-mass ratio of the metal salt solution to alumina is 1:1.5-3.0, where volume is measured in milliliters and mass in grams; and / or In step c, the temperature for static aging is 20℃-40℃, and the time is 3h-5h.

6. The method for preparing the supported molybdenum carbide catalyst as described in claim 1, characterized in that, In step d, the specific calcination steps are as follows: under a hydrogen and nitrogen atmosphere, the temperature is increased to 500℃-600℃ at a rate of 3-5℃ / min, and held for 2-4 hours; then under an ethane and argon atmosphere, the temperature is increased to 600℃-800℃ at a rate of 1-2℃ / min, and held for 4-10 hours; and / or In step d, the specific passivation steps are as follows: the cooled carrier is passivated for 4-8 hours under an argon and oxygen atmosphere.

7. A supported molybdenum carbide catalyst, characterized in that, It is prepared by the method for preparing the supported molybdenum carbide catalyst according to any one of claims 1-6.

8. The application of the supported molybdenum carbide catalyst according to claim 7 in the preparation of lower alcohols from syngas.

9. A method for producing lower alcohols from syngas, characterized in that, Includes the following steps: Silicon carbide particles are added to the top and bottom of the catalyst bed in the reactor, and the middle layer is filled with a mixture of supported molybdenum carbide catalyst and silicon carbide particles as described in claim 7. Syngas is introduced to carry out the reaction to obtain low-carbon alcohols.

10. The method for producing lower alcohols from syngas as described in claim 9, characterized in that, The synthesis gas is H2 and CO in a molar ratio of 1-2:1, the reaction temperature is 310℃-330℃, the reaction pressure is 3.0MPa-3.5MPa, and the space velocity is 3800mL·g. cat -1 ·h -1 -4200mL·g cat -1 ·h -1 .

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