A method of catalytic hydrogenation of long chain olefins 18 -C 24 A method of catalytic hydrogenation of long chain olefins

Abstract

The application relates to a method for catalytically hydrogenating C18-C24 long-chain alkenes, and belongs to the technical field of long-chain alkene hydrogenation. g The catalyst has nickel nanoparticles as an active component, and Al2O3 as a carrier. The pore size of the catalyst is about 3-5 times the average particle size of the mixed alkenes, which reduces the resistance of the alkenes to enter the pores of the catalyst, can reduce or even eliminate internal mass transfer limitations, makes the C=C double bond more easily approach the active sites, and thus the catalyst has good catalytic activity. g The prepared Ni / Al2O3 catalyst has the characteristics of high catalytic activity and easy separation, and the preparation method is simple, low in cost, high in efficiency and suitable for large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of nanometer metal catalysts, and particularly relates to a C 18 -C 24 Preparation method of long-chain olefin hydrogenation catalyst. BACKGROUND

[0002] With the rapid development of the petrochemical industry, the demand for alpha-olefins has been increasing in the market in the past two decades. At present, the method of ethylene oligomerization is mainly used in industry to produce alpha-olefins, in which C4-C 16 Olefins can be used to manufacture POE, PAO, lubricating oil, surfactant, lubricating oil additive and other products. However, C 18 and C 18 + The utilization rate of olefins is low, so how to use these by-products to produce high-value downstream products has become a common concern of many production enterprises.

[0003] C 18 -C 24 Iso-paraffins have the characteristics of abundant phase transition, such as surface crystallization, thermodynamic metastable rotating phase and thermodynamic stable low-temperature ordered phase, in the crystallization process. These phase transition characteristics make iso-paraffins have great potential as phase change materials in the rational use of heat in the fields of transportation, oil and gas industry, solar power generation device, etc. And compared with other production processes, C 18 and C 18 + The normal paraffin phase change material produced by catalytic hydrogenation of olefins as raw material contains almost no isoparaffins, naphthenes and aromatics, and does not need to be further hydrorefined and purified. Therefore, C 18 and C 18+ C 18 -C 24 Iso-paraffins are an extremely feasible way as phase change materials.

[0004] Supported catalysts used in olefin hydrogenation are mainly divided into two categories: noble metal and non-noble metal. Generally speaking, non-noble metal catalysts have more stringent reaction conditions. USPTO 20200239392 uses a palladium-supported α-Al₂O₃ catalyst. Non-noble metal catalysts generally use nickel as the active component. CN102079684 uses alumina as the support and nickel as the active component. CN112717964B uses alumina as the support and does not mix molybdenum, tungsten, zirconium, cerium, etc., into the nickel system. The main catalyst preparation methods are deposition precipitation and impregnation. CN102079684, CN112717964B, CN202111279361.0, and CN202010341475.2 use the impregnation method to prepare catalysts. The preparation process is simple and helps to reduce production costs; therefore, the impregnation method is the main method for preparing olefin hydrogenation catalysts. Compared to impregnation, catalysts prepared by deposition-precipitation methods exhibit better catalytic activity and higher dispersion, as exemplified by CN10503706413. The raw materials in these patented inventions all contain other harmful impurities, and currently there are no dedicated supported nickel catalysts for the catalytic hydrogenation of α-olefins. (The last sentence appears to be unrelated and refers to an industrial catalysis journal.) 20 + A study on the hydrogenation of mixed α-olefins to produce waxes, authored by Ren Zesheng et al., reports the use of Ni-Al alloys as catalysts, C 20 + Research results on the preparation of paraffin wax from mixed olefins via catalytic hydrogenation.

[0005] However, although the catalyst preparation methods and catalytic activities in these patented inventions are described in detail, the relationship between olefin particle size and catalyst pore size is not explained or explored in depth. The interaction between olefin particle size and catalyst pore size is crucial in catalyst design and optimization, as it directly affects the catalyst's activity and selectivity. Summary of the Invention

[0006] This invention provides a C 18 -C 24 A catalyst for the catalytic hydrogenation of long-chain olefins and its preparation method are presented. The catalyst uses nickel as the active metal and γ-Al₂O₃ as the support. The pore size of the catalyst was found to be approximately 3-5 times the average particle size of the mixed olefins. This reduces the resistance to olefin entry into the catalyst channels, decreases or even eliminates internal mass transfer limitations, and makes it easier for C=C double bonds to access the active sites, thus resulting in good catalytic activity. 18 -C 24 Long-chain olefins can be hydrogenated to produce paraffin wax, which can then be processed into phase change materials with high market demand and added value, and widely used in various fields.

[0007] This invention is achieved through the following technical solution:

[0008] A catalytic C 18 -C 24 Methods for hydrogenating long-chain olefins, catalysts and C 18 -C 24 Long-chain olefins react in a solvent for 5-30 min; the catalyst reacts with C 18 -C 24 The long-chain olefin mass ratio is 0.01 to 0.2:1, the reaction temperature is 120-150℃, the hydrogen pressure is 2-3 MPa, and the reaction device is a batch reactor.

[0009] The catalyst is prepared by:

[0010] (1) Prepare a nickel salt aqueous solution with a mass concentration of 5-25%, add ammonia to adjust the solution to alkaline, immerse the alkaline solution in γ-Al2O3, sonicate, and age overnight at room temperature under vacuum.

[0011] (2) The mixture obtained in step (1) is dried under vacuum at 60-100°C and then placed in a muffle furnace and calcined at 400-600°C for 4 hours to obtain a supported nickel catalyst precursor.

[0012] (3) The precursor obtained in step (2) is placed in a tube furnace and reduced in a hydrogen atmosphere at 400-700℃ for 3-6 hours to obtain Ni / γ-Al2O3 catalyst.

[0013] The catalyst contains 10%-20% nickel by mass, with the balance being γ-Al2O3 support.

[0014] The average pore size of the Ni / γ-Al2O3 catalyst is 10-20 nm.

[0015] The nickel salt is selected from 1 to 3 of nickel nitrate, nickel sulfate, nickel chloride, or nickel acetate.

[0016] The alumina is selected from 1-3 types of high-purity alumina, light alumina, or heavy alumina; the specific surface area of ​​the alumina is 2-250 m². 2 / g, pore volume 0.1-1cm³ 3 / g, with an average pore size of 1-10nm.

[0017] The reaction solvent is cyclohexane, and the solvent reacts with C... 18 -C 24 The mass ratio of long-chain olefins is (8-10):1.

[0018] This invention provides a C 18 -C 24A catalyst for the catalytic hydrogenation of long-chain olefins is disclosed, comprising nickel nanoparticles as the active component, γ-Al₂O₃ as the support, and ammonia water for pH adjustment. The catalyst has the following mass percentage composition: nickel 5-25%, preferably 20-25%; γ-Al₂O₃ 75-95%, preferably 75-80%. By adjusting the pH of the precursor solution with ammonia water, the surface charges of the metal precursor and the support, as well as their interactions, can be adjusted, controlling the dispersion of the active metal and thus achieving highly efficient catalytic hydrogenation of long-chain α-olefins.

[0019] Furthermore, the present invention also provides a method for using the above-mentioned nickel catalyst, the method comprising the following steps:

[0020] 1) Prepare a nickel salt aqueous solution with a mass concentration of 5-25%, add ammonia to adjust the solution to alkaline, immerse the alkaline solution in γ-Al2O3, and age overnight at room temperature;

[0021] 2) The mixture obtained in step 1) is dried under vacuum at 60-100℃, and then placed in a muffle furnace and calcined at 400-600℃ for 4 hours to obtain a supported nickel catalyst precursor.

[0022] 3) Place the precursor obtained in step 2) in a tube furnace and reduce it in a hydrogen atmosphere at 400-700℃ for 3-6 hours to obtain the Ni / γ-Al2O3 catalyst.

[0023] Furthermore, in the above preparation method, the nickel salt in step 1) is selected from any one or a combination of nickel nitrate, nickel sulfate, nickel chloride, or nickel acetate.

[0024] Furthermore, in the above preparation method, the alumina in step 1) is selected from any one or a combination of high-purity alumina, light alumina, or heavy alumina; the specific surface area of ​​the alumina is 2-250 m². 2 / g, pore volume 0.1-1cm³ 3 / g, with an average pore size of 1-10nm.

[0025] In addition, the present invention provides a C 18 -C 24Methods for investigating the relationship between the average particle size of long-chain olefins and catalyst pore size: Transmission electron microscopy (TEM) and nanoparticle size and Zeta potential analysis were used to determine the particle size distribution of long-chain olefins. Statistical distribution analysis revealed that the olefin particle length ranged from 10 nm to 90 nm, with an average length of 55.47 nm; the olefin particle width ranged from 2 nm to 10 nm, with an average width of 5.11 nm. The particle size distribution of mixed olefins was measured using nanoparticle size and Zeta potential analysis, revealing particle sizes ranging from 50 nm to 140 nm. The catalyst pore size distribution was then determined using nitrogen physical adsorption-desorption analysis. The average pore size of the γ-Al₂O₃ support was 6.81 nm, and the average pore size of the loaded catalyst reached 14.53 nm.

[0026] Finally, the present invention provides a method for catalyzing C using the above-mentioned catalyst. 18 -C 24 Methods for hydrogenation of long-chain olefins: catalysts and C 18 -C 24 The long-chain olefins are reacted in a solvent for 1-60 min, preferably 5-30 min; the reaction temperature is 100-200℃, preferably 120-150℃; the hydrogen pressure is 1-5 MPa, preferably 2-3 MPa; the catalyst and C... 18 -C 24 The mass ratio of long-chain olefins is 0.01-0.2:1, preferably 0.01-0.05:1; the reaction apparatus is a batch reactor, a loop reactor, or a fixed-bed reactor. The reaction solvent is cyclohexane, and the mass ratio of solvent to long-chain olefins is 1:1-20:1, preferably 8:1-16:1, more preferably 8:1-10:1. The beneficial effects of this application are: the hydrogenation catalyst of this invention uses nickel nanoparticles as the active component, γ-Al2O3 as the support, and ammonia water to adjust the pH. By using ammonia water to adjust the pH of the precursor solution, the charge on the surface of the metal precursor and the support and the interaction between them can be adjusted, and the dispersion of the active metal can be controlled. Compared with the pure impregnation method, the activity is higher; compared with the deposition precipitation method, the preparation process is simpler, the equipment requirements are reduced, and the overall economic cost can be significantly reduced. In addition, this invention also explored the relationship between the pore size of the catalyst and the particle size of the mixed olefins: the pore size of the catalyst is about 3-5 times the average particle size of the mixed olefins, which reduces the resistance of olefins entering the catalyst channels. This invention provides a feasible approach for designing other mixed olefin catalysts. Attached Figure Description

[0027] Figure 1 The images show representative TEM images of the mixed olefins in the raw materials of this invention (a), olefin length particle size distribution (b), olefin width particle size distribution (c), and olefin particle size distribution obtained by nanoparticle size and Zeta potential analyzer (d).

[0028] Figure 2This is the BET spectrum of the carrier γ-Al2O3(a) of the present invention.

[0029] Figure 3 The image shows the BET spectrum of the Ni / γ-Al2O3 catalyst prepared in Example 1 of this invention.

[0030] Figure 4 This is a SEM image of the 20Ni / γ-Al2O3 catalyst prepared in Example 3 of the present invention.

[0031] Figure 5 The XPS spectrum (Ni 2p) of the 20Ni / γ-Al2O3 catalyst prepared in Example 3 of this invention.

[0032] Figure 6 The image shows the XRD pattern of the Ni / γ-Al2O3 catalyst prepared in Example 3 of this invention. Detailed Implementation

[0033] The reaction apparatus used in this invention is a batch reactor, a fixed-bed reactor, or a loop reactor. Suitable process conditions are as follows: reaction temperature 100-200℃, preferably 120-150℃; reaction pressure 1-5 MPa, preferably 2-3 MPa; solvent to long-chain olefin mass ratio 1:1-20:1, preferably 8:1-16:1, more preferably 8:1-10:1; catalyst to resin mass ratio 0.01-0.2:1, preferably 0.01-0.05:1. The reaction solvent is cyclohexane.

[0034] The method and standard described in this invention are as follows: The hydrogenation rate is determined using octadecene as a model substrate, and the hydrogenation rate of octadecene is calculated by 1H NMR. The unhydrogenated octadecene raw material and dimethyl terephthalate (DMT) as an internal standard are dissolved in deuterated chloroform to prepare an ODE / DMT assay solution with a mass ratio of 1.0-5.0. 1H NMR is measured using a Bruker Avance II 400 NMR spectrometer. The integration ratio of dimethyl terephthalate (8.09 ppm) is set to 1, and the signal integration value in the double bond region (4.0–6.0 ppm) is confirmed. A set of data on the integration area corresponding to the mass ratio is obtained. Linear regression fitting is used to obtain a relationship curve (y = 0.838x - 0.66) with the proton peak integration area as the ordinate and the mass ratio as the abscissa. Similarly, the 1H NMR of the hydrogenated long-chain alkanes was measured, with the integration ratio of dimethyl terephthalate (8.09 ppm) set to 1, to confirm the signal integration value (A) of the double bond region (4.0–6.0 ppm). Using the same mass ratio data, the signal integration value (B) of the double bond was calculated by substituting it into the regression equation. The hydrogenation rate (%) was defined as (B–A) / (B) × 100, using the decrease in the signal integration value of the double bond region before and after hydrogenation (B–A) and the signal integration value of the double bond region before hydrogenation (B).

[0035] The present invention will be further described below with reference to embodiments.

[0036] γ-Al2O3 was purchased from CNOOC Tianjin Chemical Design Institute: chemically pure;

[0037] Diatomaceous earth was purchased from Maclean's: chemically pure;

[0038] ZSM-5 was purchased from Nankai University Catalyst Factory: chemically pure;

[0039] TiO2 and SiO2 were purchased from Sinopharm Chemical Reagent Company: chemically pure;

[0040] Ni(NO3)2·6H2O was purchased from Tianjin Damao Chemical Reagent Factory: analytical grade.

[0041] Example 1

[0042] Preparation of supported nickel catalysts: Supports (γ-Al2O3, ZSM-5, TiO2, SiO2, diatomaceous earth) were dried in an oven at 110℃ for 1 h, and 1 g of support was weighed to measure its saturated water absorption. 0.55 g of Ni(NO3)2·6H2O was weighed and prepared into a solution according to the saturated water absorption of the support. The solution was impregnated with 1 g of different supports, incubated overnight at room temperature, and dried under vacuum at 80℃ for 12 h. Then, it was calcined at 500℃ for 4 h to obtain the catalyst precursor. The catalyst precursor was placed in a self-made tube furnace and reduced in hydrogen at 500℃ for 4 h to obtain nickel catalysts supported on different supports.

[0043] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of octadecene. The reaction conditions were: 1g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 120℃, 3MPa. The reaction results are as follows:

[0044] Table 1. Results of octadecene hydrogenation

[0045] Catalyst Reaction time / min Hydrogenation rate / % Efficiency / mol ODE • g Ni -1 • h -1 ]]> Ni / silica 15 36.2 2844.8 Ni / gamma-Al203 15 65.4 5139.4 Ni / ZSM-5 15 44.8 3520.6 [Ni / SiO2] 30 76.0 2986.2 [Ni / TiO2] 30 45.3 1779.9

[0046] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of mixed olefins. The reaction conditions were: 1g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 130℃, 3MPa. The reaction results are as follows:

[0047] Table 2. Results of hydrogenation of mixed olefins

[0048] Catalyst Reaction time / min Hydrogenation rate / % Ni / silica 30 25.3 Ni / γ-Al2O3 30 56.1 Ni / ZSM-5 30 32.1 [Ni / SiO2] 30 15.7 [Ni / TiO2] 30 12.4

[0049] Example 2

[0050] Preparation of Ni / γ-Al2O3 catalyst: 0.26 g of Ni(NO3)2·6H2O was dissolved in 2.8 mL of deionized water to prepare a solution. The solution was then immersed in 1 g of dried γ-Al2O3 (1 g of support has a saturated water absorption capacity of 2.8 mL of water), sonicated for 30 min, aged overnight under vacuum at room temperature, and dried under vacuum at 80 °C for 12 h. The precursor was then calcined at 500 °C for 4 h to obtain the catalyst precursor. The catalyst precursor was placed in a self-made tube furnace and reduced in hydrogen at 500 °C for 4 h to obtain 5% Ni / γ-Al2O3.

[0051] Using the above method, 0.55, 0.87, 1.24, and 1.65 g of Ni(NO3)2·6H2O were weighed respectively to prepare 10%, 15%, 20%, and 25% Ni / γ-Al2O3 catalysts.

[0052] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of octadecene. The reaction conditions were: 1g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 120℃, 3MPa. The reaction results are as follows:

[0053] Table 3. Results of octadecene hydrogenation

[0054] Loading / % Reaction time / min Hydrogenation rate / % Efficiency / mol ODE • g Ni -1 • h -1 ]]> 5 10 39.1 9218.1 10 10 63.5 7485.3 15 5 61.5 9666.0 20 5 51.2 6035.4 25 5 48.0 4526.5

[0055] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of mixed olefins. The reaction conditions were: 1g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 130℃, 3MPa. The reaction results are as follows:

[0056] Table 4. Results of hydrogenation of mixed olefins

[0057] Loading / % Reaction time / min Hydrogenation rate / % 5 30 6.3 10 30 58.3 15 30 61.6 20 30 42.6 25 30 3.3

[0058] Example 3

[0059] Preparation of Ni / γ-Al2O3 catalyst: 0.26 g of Ni(NO3)2·6H2O was weighed and dissolved in 2.8 mL of deionized water to prepare a solution. Ammonia solution was added to adjust the pH to 12.5. The solution was then immersed in 1 g of dried γ-Al2O3, sonicated for 30 min, aged overnight under vacuum at room temperature, and dried under vacuum at 80 °C for 12 h. The precursor was then calcined at 500 °C for 4 h to obtain the catalyst precursor. The catalyst precursor was placed in a self-made tube furnace and reduced in hydrogen at 500 °C for 4 h to obtain 5% Ni / γ-Al2O3. 0.55, 0.87, 1.24, and 1.65 g of Ni(NO3)2·6H2O were weighed to prepare 10%, 15%, 20%, and 25% Ni / γ-Al2O3 catalysts, respectively.

[0060] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of octadecene. The reaction conditions were: 2g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 120℃, 3MPa, 5min. The reaction results are as follows:

[0061] Table 5. Results of octadecene hydrogenation

[0062] Loading / % Hydrogenation rate / % Efficiency / mol ODE ·g Ni -1 ·h -1 ]]> 5 13.2 12447.9 10 39.9 18813.4 15 60.5 19017.7 20 83.1 19591.4 25 93.5 17634.6

[0063] Catalyst performance testing: A batch reactor was used to apply the catalyst to the hydrogenation of mixed olefins. The reaction conditions were: 1g feedstock, 10mL cyclohexane solvent, 0.02g catalyst, 130℃, 3MPa. The reaction results are as follows:

[0064] Table 6. Results of hydrogenation of mixed olefins

[0065] Loading / % Reaction time / min Hydrogenation rate / % 5 30 17.4 10 30 63.9 15 30 81.8 20 30 100 25 30 76.4

[0066] The particle size distribution of long-chain olefins was determined using transmission electron microscopy and nanoparticle size and zeta potential analysis. Figure 1Particle size distribution analysis revealed that the mixed olefin particles ranged in length from 10 nm to 90 nm, with an average length of 55.47 nm; the particle width ranged from 2 nm to 10 nm, with an average width of 5.11 nm. Nanoparticle size and Zeta potential analysis were used to measure the particle size distribution, finding that the particle size ranged from 50 nm to 140 nm. Nitrogen physical adsorption-desorption analysis was combined to determine the catalyst pore size distribution. The average pore size of the γ-Al₂O₃ support was 6.81 nm, and the average pore sizes of the catalysts after loading at 5%, 10%, 15%, 20%, and 25% were 11.00, 15.89, 14.60, 17.31, and 16.07 nm, respectively. The catalyst pore size was approximately 3-5 times the average particle size of the mixed olefins, effectively reducing the resistance to olefin entry into the catalyst channels. X-ray diffraction was used to calculate the particle size of different catalysts using the Scherrer equation. Figure 6 The average particle sizes of catalysts with loadings of 5%, 10%, 15%, 20%, and 25% were 4.2, 3.6, 3.2, 4.5, and 4.4 nm, respectively. Based on a comprehensive analysis of catalyst loading, average pore size, average particle size, and their impact on hydrogenation efficiency, the average pore size and particle size of the catalyst are key factors determining the hydrogenation effect in the catalytic hydrogenation of mixed olefins. A suitable loading for the catalytic hydrogenation of mixed olefins is 10-20%.

[0067] Table 7. Physicochemical properties of Ni / γ-Al2O3 catalysts with different loadings

[0068]

[0069]

Claims

1. A type of C 18 -C 24 The method for catalytic hydrogenation of long-chain olefins is characterized by: Catalyst and C 18 -C 24 Long-chain olefins react in a solvent for 5-30 min; the catalyst reacts with C 18 -C 24 The long-chain olefin mass ratio is 0.01~0.2:1, the reaction temperature is 120-150 ℃, the hydrogen pressure is 2-3 MPa, and the reaction device is a batch reactor; The catalyst is prepared by: (1) Prepare a nickel salt aqueous solution with a mass concentration of 5-25%, add ammonia to adjust the solution to alkalinity, and immerse the alkaline solution in... γ -Aging of Al2O3 overnight at room temperature under ultrasonication and vacuum conditions; (2) The mixture obtained in step (1) is dried under vacuum at 60-100 °C and then placed in a muffle furnace and calcined at 400-600 °C for 4 h to obtain a nickel catalyst precursor. (3) The precursor obtained in step (2) is placed in a tube furnace and reduced in a hydrogen atmosphere at 400-700 °C for 3-6 h to obtain Ni / γ -Al2O3 catalyst; The catalyst contains 10%-20% nickel by mass, with the remainder being a support. γ -Al2O3; The Ni / γ The average pore size of the Al2O3 catalyst is 10-20 nm, which is 3-5 times the average particle size of the mixed olefins.

2. A C according to claim 1 18 -C 24 The method for catalytic hydrogenation of long-chain olefins is characterized by: The nickel salt is selected from 1 to 3 of nickel nitrate, nickel sulfate, nickel chloride, or nickel acetate.

3. A C according to claim 1 18 -C 24 The method for catalytic hydrogenation of long-chain olefins is characterized by: The alumina is selected from 1-3 types of high-purity alumina, light alumina, or heavy alumina; the specific surface area of ​​the alumina is 2-250 m². 2 / g, pore volume 0.1-1 cm³ 3 / g, with an average pore size of 1-10 nm.

4. A C according to claim 1 18 -C 24 The method for catalytic hydrogenation of long-chain olefins is characterized by: The solvent is cyclohexane, and the solvent reacts with C... 18 -C 24 The mass ratio of long-chain olefins is (8-10):1.

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