A cobalt oxide catalyst, its preparation method and use

Abstract

The application discloses a cobalt oxide catalyst and a preparation method and application thereof. The catalyst comprises cobalt oxide (CoO x ) nanoparticles, and can further comprise a carrier selected from gamma-alumina (gamma-Al2O3), silicon dioxide, carbon-nitrogen material, activated carbon and carbon nanotube. After calcination or reduction, the catalyst obtains active species cobalt oxide nanoparticles. The catalyst has the characteristics of low cost, simple preparation, uniform bed temperature of a fixed bed reactor, good heat and mass transfer, high production efficiency, high selectivity distribution of normal olefin products and the like. In the reaction of preparing high-value alpha-olefins through direct oligomerization of ethylene, the catalyst has the characteristics of low temperature, high activity, high selectivity of C4 and C6, and low selectivity of isomeric olefin products. Under mild reaction conditions, the initial ethylene conversion rate reaches 70%, the alpha-olefin product reaches more than 39.5%, and the catalyst has high industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical catalysts, and relates to preparation and application of a cobalt oxide catalyst, in particular to a cobalt oxide catalyst for preparing high-value alpha-olefins by heterogeneous ethylene oligomerization and a preparation method and application thereof. BACKGROUND

[0002] Linear alpha-olefins (LAO) generally refer to high-carbon straight-chain alkenes with C4 and above double bonds at the end of the carbon chain, including 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecane and the like, which are important chemical raw materials and intermediates, can be used to produce polyolefin comonomers, detergent alcohols, plasticizer alcohols, PAO base oils and oil additives, are basic raw materials for preparing high-value chemicals, and are widely used in petrochemical industry, light industry, textile, metallurgy, and medicine, pesticide and the like.

[0003] Ethylene oligomerization to prepare linear alpha-olefins is an important reaction in the preparation of high-value chemicals from olefins, and the related industry has a deep history. However, due to the continuous innovation of catalyst types, production processes and applications, the industry is still growing steadily and maintaining technical driving. The continuous driving force for the linear alpha-olefin production industry lies in the design of efficient catalysts and the upgrading of related processes. Linear alpha-olefins have a wide range of applications and are rapidly developing driven by downstream industries, and their output value is increasing worldwide, with significant economic benefits. With strong market demand, international petrochemical companies such as Shell and INEOS are continuously expanding the scale of the linear alpha-olefin industry. With the development of synthetic materials and fine chemicals in China, the demand for LAO is increasing, and petrochemical companies and related research institutions in China are joining the ranks of the industry, actively promoting the research and development and production process of linear alpha-olefins. Currently, homogeneous olefin oligomerization catalysts mainly use organometallic, metallocene complexes and alkyl aluminum additives as the core, which can obtain high activity and target olefin selectivity, but they also face problems such as extreme sensitivity to impurities, difficulty in separation, expensive ligands, and easy corrosion of equipment. Therefore, the development of environmentally friendly, inexpensive and easily available heterogeneous oligomerization catalysts is attracting attention. Heterogeneous catalysts have made some progress in olefin oligomerization research, but there are still problems such as activity and selectivity, poor stability, and unclear reaction mechanism and structure-activity relationship. Therefore, it is necessary to develop new ethylene heterogeneous oligomerization technology to further improve the catalytic performance. SUMMARY

[0004] The present application aims to provide a cobalt oxide catalyst for preparing high-value alpha-olefins by heterogeneous ethylene oligomerization and its preparation method and application. The catalyst of the present application is used in a fixed bed reactor, has uniform reactor bed temperature, good heat and mass transfer, high production efficiency, low purity requirement for reaction gas, high initial conversion rate of ethylene, high selectivity distribution of normal olefin products, mild reaction conditions, simple catalyst preparation method, low cost, renewable and recyclable use, etc. It can make up for the defects of homogeneous catalysts, such as high sensitivity to impurities such as air, expensive ligands, complex preparation, difficult regeneration of deactivated catalysts and non-recyclable use. Due to the simple preparation method of the cobalt oxide catalyst for heterogeneous ethylene oligomerization, easy repeatability, renewable use after deactivation, etc., it has potential industrial application value.

[0005] The present application first provides a cobalt catalyst (Co catalyst) which can be used for preparing high-value alpha-olefins by heterogeneous ethylene.

[0006] The active species of the catalyst is cobalt oxide (CoO x ) nanoparticles. The cobalt oxide (CoO x ) nanoparticles are prepared by calcination or reduction of the Co catalyst.

[0007] The cobalt catalyst can also contain an auxiliary agent, which is composed of one or more of Mn, Fe, Ru, Rh, Pt and other transition metals or noble metals.

[0008] The pH value of the cobalt catalyst can be adjusted by a pH solution composed of one or more of NH4OH, HNO3 and deionized water.

[0009] The cobalt catalyst can also contain a carrier, which is composed of one or more of γ-alumina (γ-Al2O3), silicon dioxide (SiO2), carbon-nitrogen material (C3N4), activated carbon (AC) and carbon nanotube (CNT).

[0010] Preferably, in the cobalt catalyst, the content of the auxiliary agent accounts for less than 10% of the total mass of the catalyst.

[0011] Preferably, the cobalt catalyst is prepared by impregnation method.

[0012] Preferably, the preparation method of the cobalt catalyst comprises the following steps:

[0013] 1) According to the composition ratio of the catalyst, the metal active components and the salts of the auxiliary agent are configured into a uniform mixed salt solution in a certain molar ratio; the molar concentration of the total metal salt of the mixed salt solution is 0.01-5 mol / L; the metal salt is one or more of corresponding chloride, nitrate, sulfate, oxalate or acetate;

[0014] 2) Pretreatment of different carriers, γ-alumina (γ-Al2O3) and silicon dioxide (SiO2) need to be spray dried to obtain uniform nanospherical particles; carbon-nitrogen material (C3N4) is prepared by placing an appropriate amount of urea in a crucible and calcining in a muffle furnace, heating at a rate of 5℃ / min to 550℃ and maintaining for 4h at room temperature; activated carbon and carbon nanotubes are respectively placed in a single-necked flask, 50% concentrated nitric acid is slowly added to cover, and stirring is performed with a magnetic stirrer in an oil bath of a fume hood at 80℃ and reflux heating for 2h; then, the activated carbon or carbon nanotubes cooked with acid are washed with distilled water and suction filtered multiple times until neutral, and then placed in an oven at 80-150℃ for drying for 12h, and sieved out after 40-60 mesh, and then used;

[0015] 3) Modification treatment of the carrier obtained in step 2) with different pH solutions, impregnate the carrier with a specific concentration of pH solution and stir uniformly, first stand for 2h-8h in a fume hood, and then place in an oven at 80-150℃ for 2h-8h for standby; the pH solution includes one or more of NH4OH, HNO3 and deionized water, and the carrier is one or more of γ-alumina (γ-Al2O3), silicon dioxide (SiO2), carbon-nitrogen material (C3N4), activated carbon (AC) and carbon nanotubes (CNT);

[0016] 4) Impregnate the modified carrier prepared in step 3) with the mixed salt solution prepared in step 1) in equal volume, first stand for 2h-10h in a fume hood, and then place in an oven at 80-150℃ for 2h-10h;

[0017] 5) Modification treatment of the catalyst precursor prepared in step 4) with a corresponding concentration of pH solution, fully stir, consistent with step 2), the pH solution includes one or more of NH4OH, HNO3 and deionized water; also stand for 2h-10h in a fume hood, and then place in an oven at 80-150℃ for 2h-10h;

[0018] 6) The final catalyst obtained by calcination or reduction of the catalyst precursor obtained in step 5) in a fixed bed reactor is used for reaction; the calcination gas can be nitrogen, argon or helium; the reduction gas can be hydrogen, CO or diluted hydrogen; the calcination temperature is 200℃-800℃, the reduction temperature is 200℃-400℃, the calcination or reduction time is controlled at 1-5h, the calcination or reduction space velocity is 6000-20000h-1, and the calcination or reduction pressure is atmospheric pressure; -1

[0019] Preferably, the total metal salt molar concentration of the mixed salt solution in step 1) is 0.5-3mol / L; and the metal salt is preferably a nitrate salt;

[0020] ​In the step 3), the pH solution comprises one or more of NH4OH, HNO3 and deionized water, the concentration of NH4OH is 28-30 wt%, and the concentration of HNO3 is 45-55 wt%.

[0021] In the steps 3), 4) and 5), the standing temperature at room temperature is 20-35℃, preferably 25-30℃, and the time is preferably 4-8h; the oven drying temperature is 80-140℃, and the time is 4-8h; the oven drying can be carried out under vacuum, air atmosphere or inert atmosphere, and the vacuum condition is more preferred.

[0022] In the step 6), the calcination gas can be nitrogen, argon or helium, and the reduction gas can be hydrogen, CO or diluted hydrogen, preferably the calcination gas is argon or helium; the calcination temperature is 200-800℃, preferably 230-550℃; the calcination time is 1-5h, preferably 2-3h; and the calcination space velocity is 6000-20000h -1 , preferably 8000-15000h -1 .

[0023] The preparation method of the cobalt oxide catalyst for preparing high-value alpha-olefins by ethylene heterogeneous oligomerization comprises the following steps:

[0024] 1) The cobalt catalyst precursor is activated by high-temperature inert gas or reduction gas;

[0025] 2) After the calcination or reduction is completed, the mixed gas containing ethylene is introduced into the system in step 1) at room temperature for purging, and the cobalt oxide catalyst for preparing high-value alpha-olefins by ethylene heterogeneous oligomerization is obtained after the purging is completed.

[0026] In the step 2), the purging and reaction gas is a mixed gas containing ethylene, methane and dilution gas, wherein the methane is an internal standard gas with a proportion of 5%, and the dilution medium can be nitrogen, argon or helium; the volume content of ethylene gas is 5-95%, preferably 40-60%.

[0027] The application also discloses the use of the cobalt oxide catalyst in the field of preparing high-value alpha-olefins by ethylene heterogeneous oligomerization, the reactor for synthesizing olefins is a fixed bed reactor; the volume fraction of the raw material gas ethylene used in the reaction is 5-95%, preferably 40-60%; the reaction temperature is 50-500℃, preferably 75-200℃; the reaction pressure is 0.5-4MPa, preferably 1-3MPa; and the reaction space velocity is 2500-10000h -1 , preferably 3000-6000h -1 .

[0028] The technical effects of the application include:

[0029] The application provides a preparation method of a catalyst for preparing high-value alpha-olefins by heterogeneous ethylene oligomerization, which has the advantages of simple reaction process, low cost, mild reaction conditions, renewable and recyclable use, etc. The prepared cobalt catalyst is used in a fixed bed reactor, which has the characteristics of uniform bed temperature, good heat and mass transfer, high production efficiency, and high selectivity distribution of normal olefin products. The prepared cobalt catalyst is used for preparing high-value olefins by ethylene oligomerization, and the catalyst has the characteristics of low temperature, high activity, high selectivity of C4 and C6, and low selectivity of isomerized olefin products. Under mild reaction conditions, the selectivity of alpha-olefin products reaches 39.5%, the initial conversion rate of ethylene can reach more than 70.3%, the catalyst can be recycled, and has great application prospect in the fixed bed reactor, and has high economic value and potential industrial application prospect. DETAILED DESCRIPTION

[0030] The embodiments of the present application are described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. The present application can also be implemented or applied by other different embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0031] It should be understood that the process equipment or device not specifically mentioned in the following examples is conventional equipment or device in the art; all pressure values and ranges refer to relative pressure.

[0032] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude the presence of other method steps before and after the combination steps or the insertion of other method steps between the explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present application does not exclude the presence of other devices / apparatuses before and after the combination devices / apparatuses or the insertion of other devices / apparatuses between the two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not a limitation on the arrangement order of each method step or a limitation on the range of the present application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of the present application.

[0033] Example 1

[0034] The activated carbon was heated with 50% concentrated nitric acid at 80°C for 2h, washed with distilled water, filtered to neutral, dried in an oven at 130°C for 12h, and sieved to 40-60 mesh for use. CoCO3-H2O was dissolved in a certain amount of deionized water to form a salt solution with a total metal concentration of 2.4 mol / L as a precursor salt solution, and was impregnated in the activated carbon prepared above by an equal volume impregnation method. After standing in a fume hood for 4h, the precursor catalyst was obtained by placing it in an oven at 80°C for 4h. The precursor catalyst was filled in a fixed bed reactor, calcined at 300°C for 1h under normal pressure in a N2 atmosphere with a space velocity of 6000h-1, and a final catalyst was obtained. -1 The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. The catalyst was first in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 40%, CH4, 5%, N2, 55%) with CH4 as an internal standard for 0.5h. The back pressure was then increased to 1 MPa, and the temperature was increased to 60°C at a rate of 2°C / min. The reaction was carried out at a space velocity of 2500h-1. The reaction results are shown in Table 1.

[0035] The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. The catalyst was first in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 40%, CH4, 5%, N2, 55%) with CH4 as an internal standard for 0.5h. The back pressure was then increased to 1 MPa, and the temperature was increased to 60°C at a rate of 2°C / min. The reaction was carried out at a space velocity of 2500h-1. The reaction results are shown in Table 1. -1

[0036] Example 2

[0037] The activated carbon was heated with 50% concentrated nitric acid at 80°C for 2h, washed with distilled water, filtered to neutral, dried in an oven at 130°C for 12h, and sieved to 40-60 mesh for use. CoCO3-H2O was dissolved in a certain amount of deionized water to form a salt solution with a total metal concentration of 2.4 mol / L as a precursor salt solution, and was impregnated in the activated carbon prepared above by an equal volume impregnation method. After standing in a fume hood for 4h, the precursor catalyst was obtained by placing it in an oven at 80°C for 4h. The precursor catalyst was filled in a fixed bed reactor, calcined at 300°C for 1h under normal pressure in a N2 atmosphere with a space velocity of 6000h-1, and a final catalyst was obtained. -1 The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. The catalyst was first in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 40%, CH4, 5%, N2, 55%) with CH4 as an internal standard for 0.5h. The back pressure was then increased to 1 MPa, and the temperature was increased to 60°C at a rate of 2°C / min. The reaction was carried out at a space velocity of 2500h-1. The reaction results are shown in Table 1.

[0038] ​The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 50%, CH4, 5%, N2, 45%) using CH4 as an internal standard for 0.5 h. Then, the back pressure was increased to 2 MPa, and the temperature was increased to 80 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 3000 h -1 The reaction results are shown in Table 1.

[0039] Example 3

[0040] The carbon nanotubes were refluxed with 50% concentrated nitric acid at 80 °C for 2 h, washed with distilled water, and filtered until neutral. Then, the carbon nanotubes were dried in an oven at 130 °C for 12 h, sieved to 40-60 mesh, and then 28% nitric acid solution was added dropwise while stirring. After being placed in a fume hood for 6 h, the carbon nanotubes were dried in a vacuum drying oven at 100 °C for 6 h. CoCl2·6H2O was dissolved in a certain amount of deionized water to form a salt solution with a total metal concentration of 2.4 mol / L as a precursor salt solution. The carbon nanotubes were impregnated with the salt solution by an equal volume impregnation method. After being placed in a fume hood for 6 h, the carbon nanotubes were placed in an oven at 100 °C for 6 h. Then, 28% nitric acid solution was added dropwise while stirring on the dried catalyst impregnated with the chlorinated salt solution precursor. After being placed in a fume hood for 6 h, the catalyst was dried in a vacuum drying oven at 100 °C for 6 h to obtain a precursor catalyst. The precursor catalyst was filled into a fixed bed reactor and calcined at 200 °C for 1.5 h under a He atmosphere at a space velocity of 10000 h -1 The final catalyst was obtained.

[0041] The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 50%, CH4, 5%, N2, 45%) using CH4 as an internal standard for 0.5 h. Then, the back pressure was increased to 2 MPa, and the temperature was increased to 80 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 3000 h -1 The reaction results are shown in Table 1.

[0042] Example 4

[0043] The γ-alumina (γ-Al2O3) was spray dried to obtain uniform nanospherical particles, and then 28% ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 h, the sample was placed in a vacuum drying oven at 130°C for 8 h. CoSO4-7H2O was dissolved in deionized water to form a salt solution with a total metal concentration of 3.5 mol / L as a precursor salt solution, which was used to impregnate the above-prepared γ-alumina by the equal volume impregnation method. After standing in a fume hood for 5 h, the sample was placed in an oven at 90°C for 5 h. After drying of the impregnated sulfate solution precursor, 28% ammonia solution was added dropwise while stirring. After standing in a fume hood for 5 h, the sample was placed in a vacuum drying oven at 90°C for 5 h to obtain a precursor catalyst. The precursor catalyst was filled into a fixed bed reactor and reduced at 200°C for 1 h under normal pressure in a hydrogen atmosphere with a space velocity of 12000 h-1to obtain a final catalyst. -1 The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, in-situ calcination (i.e. activation) of the catalyst was performed. After the process was completed and the temperature dropped to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 60%, CH4, 5%, N2, 35%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 4 MPa, and the temperature was increased to 300°C at a rate of 2°C / min. The reaction was performed at a space velocity of 6000 h-1. The reaction results are shown in Table 1.

[0044] The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, in-situ calcination (i.e. activation) of the catalyst was performed. After the process was completed and the temperature dropped to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 60%, CH4, 5%, N2, 35%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 4 MPa, and the temperature was increased to 300°C at a rate of 2°C / min. The reaction was performed at a space velocity of 6000 h-1. The reaction results are shown in Table 1. -1 The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, in-situ calcination (i.e. activation) of the catalyst was performed. After the process was completed and the temperature dropped to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 60%, CH4, 5%, N2, 35%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 4 MPa, and the temperature was increased to 300°C at a rate of 2°C / min. The reaction was performed at a space velocity of 6000 h-1. The reaction results are shown in Table 1.

[0045] Example 5

[0046] The silica (SiO2) was spray dried to obtain uniform nanospherical particles, and then 28% ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 h, the sample was placed in a vacuum drying oven at 130°C for 8 h. C4H 14 CoO8 was dissolved in deionized water to form a salt solution with a total metal concentration of 3.5 mol / L as a precursor salt solution, which was used to impregnate the above-prepared silica by the equal volume impregnation method. After standing in a fume hood for 7 h, the sample was placed in an oven at 110°C for 5 h. After drying of the impregnated sulfate solution precursor, 28% ammonia solution was added dropwise while stirring. After standing in a fume hood for 7 h, the sample was placed in a vacuum drying oven at 110°C for 7 h to obtain a precursor catalyst. The precursor catalyst was filled into a fixed bed reactor and reduced at 300°C for 3 h under normal pressure in a CO atmosphere with a space velocity of 14000 h -1 The catalyst was used in the reaction of preparing high-value α-olefins by ethylene heterogeneous oligomerization. The reaction device was a fixed bed reactor. First, in-situ calcination (i.e. activation) of the catalyst was performed. After the process was completed and the temperature dropped to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 60%, CH4, 5%, N2, 35%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 4 MPa, and the temperature was increased to 300°C at a rate of 2°C / min. The reaction was performed at a space velocity of 6000 h-1. The reaction results are shown in Table 1.

[0047] The catalyst was used in the reaction of preparing high-value α-olefins by the heterogeneous oligomerization of ethylene. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 65%, CH4, 5%, N2, 30%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 3 MPa, and the temperature was increased to 400 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 7000 h -1 -1. The reaction results are shown in Table 1.

[0048] Example 6

[0049] The carbon-nitrogen material (C3N4) was prepared by placing an appropriate amount of urea in a crucible and calcining it in a muffle furnace at a rate of 5 °C / min to 550 °C and maintaining it for 4 h at room temperature. A 28% ammonia solution was added dropwise while stirring until use. After standing in a fume hood for 8 h, the sample was placed in a vacuum drying oven at 130 °C for 8 h for standby use. Cobalt hydroxide oxalate was dissolved in a certain amount of deionized water to form a salt solution with a total metal concentration of 3.8 mol / L as a precursor salt solution. The carbon-nitrogen material prepared above was impregnated with an equal volume of the salt solution, and then stood in a fume hood for 3 h. After drying, the catalyst was continuously stirred and a 28% ammonia solution was added dropwise until use. After standing in a fume hood for 3 h, the precursor catalyst was placed in a vacuum drying oven at 120 °C for 3 h. The precursor catalyst was packed in a fixed bed reactor and reduced at 200 °C for 1 h under atmospheric pressure in a dilute hydrogen atmosphere at a space velocity of 16000 h -1 -1. The final catalyst was obtained.

[0050] The catalyst was used in the reaction of preparing high-value α-olefins by the heterogeneous oligomerization of ethylene. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 65%, CH4, 5%, N2, 30%) using CH4 as an internal standard for 0.5 h. The back pressure was then increased to 3 MPa, and the temperature was increased to 400 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 7000 h -1 -1. The reaction results are shown in Table 1.

[0051] Example 7

[0052] Activated carbon was refluxed with 50% concentrated nitric acid at 80℃ for 2 hours, washed with distilled water and filtered until neutral. It was then dried in a 130℃ oven for 12 hours, sieved to a mesh size of 40-60 mesh, and then 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 hours, it was placed in a vacuum drying oven at 130℃ for 8 hours for later use. Co(NO3)2·6H2O and Mn(NO3)2·4H2O were dissolved in a certain amount of deionized water to form a mixed salt solution with a total metal concentration of 5.2 mol / L, which served as the precursor salt solution. This solution was impregnated onto the prepared activated carbon using an equal-volume impregnation method. After standing in a fume hood for 6 hours, it was placed in a 140℃ oven for 6 hours. On the dried catalyst impregnated with the mixed nitrate solution precursor, 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 6 hours, it was placed in a vacuum drying oven at 140℃ for 6 hours to obtain the precursor catalyst. The precursor catalyst was packed in a fixed-bed reactor and subjected to atmospheric pressure and a space velocity of 14000 h⁻¹. -1 The catalyst was calcined at 400℃ for 3.5 h in an Ar atmosphere to obtain the final catalyst.

[0053] This catalyst is used in the multiphase oligomerization of ethylene to prepare high-value α-olefins. The reaction apparatus is a fixed-bed reactor. First, the catalyst undergoes in-situ calcination (activation). After this process and the temperature drops to room temperature, the catalyst is purged for 0.5 h with a diluted ethylene gas mixture (C2H4, 75%, CH4, 5%, N2, 20%) using CH4 as an internal standard. Then, the back pressure is increased to 2.5 MPa, and the temperature is raised to 150 °C at a rate of 2 °C / min for the reaction. The reaction space velocity is 4000 h⁻¹. -1 The reaction results are shown in Table 1.

[0054] Example 8

[0055] Activated carbon was refluxed with 50% concentrated nitric acid at 80℃ for 2 hours, washed with distilled water and filtered until neutral. It was then dried in a 130℃ oven for 12 hours, sieved to a mesh size of 40-60, and then 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 hours, it was placed in a vacuum drying oven at 130℃ for 8 hours. Co(NO3)2·6H2O and Fe(NO3)3·9H2O were dissolved in a certain amount of deionized water to form a mixed salt solution with a total metal concentration of 5.5 mol / L, which served as the precursor salt solution. This solution was impregnated onto the prepared activated carbon using an equal-volume impregnation method. After standing in a fume hood for 7 hours, it was placed in a 130℃ oven for 7 hours. On the dried catalyst impregnated with the mixed nitrate solution precursor, 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 7 hours, it was placed in a vacuum drying oven at 130℃ for 7 hours to obtain the precursor catalyst. The precursor catalyst was packed in a fixed-bed reactor and subjected to atmospheric pressure and a space velocity of 14000 h⁻¹. -1 The catalyst was calcined at 500°C for 3 hours in a N2 atmosphere to obtain the final catalyst.

[0056] The catalyst was used in the reaction of ethylene heterogeneous oligomerization to prepare high-value α-olefins. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 80%, CH4, 5%, N2, 15%) with CH4 as an internal standard for 0.5 h. Then, the back pressure was increased to 3 MPa, and the temperature was increased to 180 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 4500 h-1. -1 The reaction results are shown in Table 1.

[0057] Example 9

[0058] The activated carbon was heated with 50% concentrated nitric acid at 80 °C for 2 h. The activated carbon was washed with distilled water, filtered, and dried in an oven at 130 °C for 12 h. Then, the activated carbon was sieved to obtain 40-60 mesh. Then, 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 h, the activated carbon was placed in a vacuum drying oven at 130 °C for 8 h. Co(NO3)2·6H2O and ruthenium nitrosyl nitrate were dissolved in a certain amount of deionized water to form a mixed salt solution with a total metal concentration of 3.8 mol / L as a precursor salt solution. The activated carbon prepared above was impregnated with the precursor salt solution by the equal volume impregnation method. After standing in a fume hood for 8 h, the activated carbon was placed in an oven at 120 °C for 8 h. Then, 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 h, the activated carbon was placed in a vacuum drying oven at 120 °C for 8 h to obtain a precursor catalyst. The precursor catalyst was filled into a fixed bed reactor and calcined at 450 °C for 2.5 h under a He atmosphere at a space velocity of 15000 h-1at normal pressure to obtain a final catalyst. -1

[0059] The catalyst was used in the reaction of ethylene heterogeneous oligomerization to prepare high-value α-olefins. The reaction device was a fixed bed reactor. First, the catalyst was in-situ calcined (i.e. activated). After the process was completed and the temperature was reduced to room temperature, the catalyst was purged with a dilute ethylene mixed gas (C2H4, 80%, CH4, 5%, N2, 15%) with CH4 as an internal standard for 0.5 h. Then, the back pressure was increased to 3.5 MPa, and the temperature was increased to 150 °C at a rate of 2 °C / min. The reaction was carried out at a space velocity of 5000 h-1. -1 The reaction results are shown in Table 1.

[0060] Example 10

[0061] ​Activated carbon was refluxed with 50% concentrated nitric acid at 80℃ for 2 hours, washed with distilled water and filtered until neutral. It was then dried in a 130℃ oven for 12 hours, sieved to a mesh size of 40-60 mesh, and then 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 hours, it was placed in a vacuum drying oven at 130℃ for 8 hours. Co(NO3)2·6H2O and rhodium chloride solution were dissolved in a certain amount of deionized water to form a mixed salt solution with a total metal concentration of 3.7 mol / L, which served as the precursor salt solution. This solution was impregnated onto the prepared activated carbon using an equal-volume impregnation method. After standing in a fume hood for 9 hours, it was placed in a 110℃ oven for 8 hours. 28% concentrated ammonia solution was added dropwise while stirring on the dried catalyst impregnated with the mixed salt solution precursor. After standing in a fume hood for 8 hours, it was placed in a vacuum drying oven at 110℃ for 9 hours to obtain the precursor catalyst. The precursor catalyst was packed in a fixed-bed reactor and subjected to atmospheric pressure and a space velocity of 16000 h⁻¹. -1 The catalyst was calcined at 400°C for 1.5 h in an Ar atmosphere to obtain the final catalyst.

[0062] This catalyst is used in the heterogeneous oligomerization of ethylene to prepare high-value α-olefins. The reaction apparatus is a fixed-bed reactor. First, the catalyst undergoes in-situ calcination (activation). After this process and the temperature drops to room temperature, the catalyst is purged for 0.5 h with a diluted ethylene mixture (C2H4, 85%, CH4, 5%, N2, 10%) using CH4 as an internal standard. Then, the back pressure is increased to 3 MPa, and the temperature is raised to 200 °C at a rate of 2 °C / min for the reaction. The reaction space velocity is 5500 h⁻¹. -1 The reaction results are shown in Table 1.

[0063] Example 11

[0064] Activated carbon was refluxed with 50% concentrated nitric acid at 80℃ for 2 hours, washed with distilled water and filtered until neutral. It was then dried in a 130℃ oven for 12 hours, sieved to a mesh size of 40-60 mesh, and then 28% concentrated ammonia solution was added dropwise while stirring. After standing in a fume hood for 8 hours, it was placed in a vacuum drying oven at 130℃ for 8 hours. Co(NO3)2·6H2O and platinum chloride solution were dissolved in a certain amount of deionized water to form a mixed salt solution with a total metal concentration of 3.8 mol / L, which served as the precursor salt solution. This solution was impregnated onto the prepared activated carbon using an equal-volume impregnation method. After standing in a fume hood for 10 hours, it was placed in a 100℃ oven for 10 hours. 28% concentrated ammonia solution was added dropwise while stirring on the dried catalyst impregnated with the mixed salt solution precursor. After standing in a fume hood for 10 hours, it was placed in a vacuum drying oven at 100℃ for 10 hours to obtain the precursor catalyst. The precursor catalyst was packed in a fixed-bed reactor and subjected to atmospheric pressure and a space velocity of 18000 h⁻¹. -1 The catalyst was calcined at 300°C for 2 hours in a N2 atmosphere to obtain the final catalyst.

[0065] This catalyst is used in the multiphase oligomerization of ethylene to prepare high-value α-olefins. The reaction apparatus is a fixed-bed reactor. First, the catalyst undergoes in-situ calcination (activation). After this process and the temperature drops to room temperature, the catalyst is purged for 0.5 h with a diluted ethylene mixture (C2H4, 50%, CH4, 5%, N2, 45%) using CH4 as an internal standard. Then, the back pressure is increased to 2.5 MPa, and the temperature is raised to 250 °C at a rate of 2 °C / min for the reaction. The reaction space velocity is 6000 h⁻¹. -1 The reaction results are shown in Table 1.

[0066] Table 1: Catalyst Reaction Results of Examples

[0067]

[0068] As shown in Table 1, the cobalt oxide catalyst obtained by calcination and reduction of the catalyst described in this invention can efficiently synthesize high-value olefins in a fixed-bed reactor. Specifically, the catalyst described in this invention (Example 2) was tested at 80°C, 2 MPa, and 3000 h⁻¹. -1 At the specified space velocity, the initial ethylene conversion was 70.3%, corresponding to a high carbon selectivity of 39.5% for α-olefins. The olefin distribution, from lowest to highest content, was butene, hexene, octene, and decene, consistent with the SF distribution. The cobalt oxide catalyst described in this invention exhibits excellent performance in producing high-value olefins from ethylene, and its preparation is convenient and low-cost, showing potential for industrial application.

Claims

1. A process for the preparation of a cobalt catalyst for the heterogeneously preparing high value alpha-olefins from ethylene, characterized in that, The method comprises the following steps: 1) According to the catalyst composition ratio, the active component of the catalyst metal and the salt of the auxiliary agent are configured into a uniform mixed salt solution in a certain molar ratio; the active component of the cobalt catalyst includes cobalt oxide CoO x nanoparticles; the auxiliary agent is composed of one or more of Mn, Fe, Ru, Rh and Pt; the total molar concentration of metal ions in the mixed salt solution is 0.01 mol / L~5 mol / L; 2) Preparation of different carriers; the carrier is composed of one or more of γ-alumina, silicon dioxide, carbon-nitrogen material, activated carbon and carbon nanotubes; γ-alumina (γ-Al2O3) and silicon dioxide (SiO2) need to be spray dried to obtain uniform nanometer spherical particles; carbon-nitrogen material C3N4 is prepared by placing an appropriate amount of urea in a crucible and calcining in a muffle furnace, heating at a rate of 5 ℃ / min to 550 ℃ and maintaining for 4 h at room temperature; activated carbon and carbon nanotubes are respectively placed in a single-necked flask, 50% concentrated nitric acid is slowly added to cover, and the mixture is stirred with a magnetic stirrer and heated under reflux in an oil bath of a fume hood at 80 ℃ for 2 h; then, the activated carbon or carbon nanotubes cooked with acid are washed with distilled water and suction filtered multiple times until neutral, and then dried in an oven at 130 ℃ for 12 h, sieved out to 40-60 mesh, and then used; 3) According to the composition ratio of the catalyst, the carrier obtained in step 2) is modified by a pH solution, the carrier is impregnated with a specific concentration of a pH solution and stirred uniformly, first placed in a fume hood for 2 h~8 h, and then placed in an oven at 120~150 ℃ for 2 h~8 h for standby; the pH solution is a 28% ammonia water solution; 4) The mixed salt solution prepared in step 1) and the modified carrier prepared in step 3) are impregnated in equal volumes, first placed in a fume hood for 2 h~10 h, and then placed in an oven at 120~150 ℃ for 2 h~10 h; 5) The catalyst precursor prepared in step 4) is modified by a corresponding concentration of a pH solution, fully stirred, consistent with step 3), and also placed in a fume hood for 2 h~10 h, and then placed in an oven at 120~150 ℃ for 2 h~10 h; the pH solution is a 28% ammonia water solution; 6) the catalyst precursor obtained in step 5) is calcined in a fixed bed reactor to obtain the final catalyst; the calcination gas is nitrogen, argon, helium; the calcination temperature is 200 ℃-800 ℃, the calcination time is controlled to be 1-5 h; the calcination space velocity is 6000-20000 h -1 , and the calcination pressure is normal pressure.

2. The production method according to claim 1, wherein The content of the additive is less than 10% of the total mass percentage of the catalyst.

3. The production method according to claim 1, wherein After the calcination in step 6) is completed, a mixed gas containing ethylene is introduced into the system in step 6) at room temperature for purging, and the cobalt oxide catalyst for the preparation of high-value olefins by the heterogeneous oligomerization of ethylene is obtained after the purging is completed.

4. The method of claim 3, wherein, The purging and reaction gas are a mixed gas containing ethylene, methane and diluent gas, wherein the methane is an internal standard gas with a proportion of 5%, the diluent medium is nitrogen, argon or helium, and the volume content of the diluent gas is 0~90% and not 0.

5. A cobalt catalyst characterized by: The cobalt catalyst for the preparation of high-value α-olefins by the heterogeneous oligomerization of ethylene is prepared by the method of any one of claims 1-4.

6. The application of the cobalt catalyst prepared by the method of any one of claims 1-4 for the preparation of high-value α-olefins by the heterogeneous oligomerization of ethylene.

7. Use according to claim 6, wherein The reactor for preparing high-value olefins by heterogeneous oligomerization of ethylene is a fixed bed reactor; the reaction temperature is 50-500 DEG C; the reaction pressure is 0.5-4 MPa; the reaction space velocity is 2500-10000 h -1 .

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