Preparation method of high-filling-rate carbon nanotube confined hydrogenation catalyst

Abstract

This invention relates to the field of catalytic hydrogenation catalyst preparation technology, and particularly to a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst. The method uses short multi-walled carbon nanotubes as the encapsulation support and transition metal inorganic salts and transition metal organic compounds as their metal precursors. The preparation process is simple, with a high internal filling rate and significant catalytic hydrogenation effect. In this method, the catalyst support is 100 nm ultra-short multi-walled carbon nanotubes, and the active component is one or more combinations of transition metals such as nickel, copper, and iron. The ultra-short multi-walled carbon nanotubes greatly improve the internal filling efficiency of the active component and increase mass transfer efficiency. The prepared catalyst is suitable for carbon dioxide hydrogenation and heavy oil hydrogenation processes. The catalyst exposes more active sites, while the protection of the support ensures high stability of the internal active component, effectively preventing aggregation and greatly improving catalyst performance.

Description

Technical Field

[0001] This invention relates to the field of catalytic hydrogenation catalyst preparation technology, and in particular to a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst. Background Technology

[0002] With the increasing weight and viscosity of crude oil and the growing demand for light oil products, heavy oil processing has become a major challenge for modern refineries. Currently, heavy oil processing mainly involves four processes: delayed coking, viscosity-reducing cracking, heavy oil catalytic cracking, and heavy oil hydrotreating. Delayed coking and viscosity-reducing cracking are thermal processing methods, characterized by their ability to process various types of residue oil, but resulting in poor quality liquid products and high coke yield. Heavy oil catalytic cracking has high requirements for feedstock and cannot process low-quality residue oil. Heavy oil hydrotreating can process low-quality residue oil with high sulfur, high carbon residue, and high metal content, while also improving liquid yield and the quality of liquid products. The catalyst, as the core component of this technology, directly affects the severity of reaction conditions and the quality of the product, making it a current hot topic in catalytic hydrotreating technology.

[0003] However, catalysts often face problems such as low conversion rate, high reaction temperature, and catalyst poisoning during the reaction process. Improving catalyst activity can effectively increase the conversion rate and reduce the reaction temperature, but at the same time, it will also face problems such as catalyst poisoning and short catalyst life. These two aspects are mutually restrictive. Therefore, encapsulating the active components in a microenvironment can effectively protect the internal active components, prevent their aggregation, and expose more active sites.

[0004] Nanotechnology and the unique physical and chemical properties of nanoparticles have attracted widespread attention and have received extensive attention in the field of catalysis research. The modulating effect of carbon nanotubes on the redox properties of metals and their oxides assembled in their channels is of great significance for catalytic reactions, especially hydrogen-related reactions. At present, the filling efficiency of active components can reach about 80%. Improving the internal filling efficiency of active components can better improve the performance of catalysts. Summary of the Invention

[0005] This invention provides a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, using short multi-walled carbon nanotubes as the encapsulation carrier and transition metal inorganic salts and transition metal organic compounds as their metal precursors. The preparation process is simple, with a high internal filling rate and significant catalytic hydrogenation effect.

[0006] The preparation method of the confined hydrogenation catalyst includes:

[0007] (1) 65% concentrated nitric acid and 98% concentrated sulfuric acid were added to a flask at a volume ratio of 1:2 to 4, and a certain amount of 2μm multi-walled carbon nanotubes were added to react and obtain an acidified multi-walled carbon nanotube mixed solution. The acidified multi-walled carbon nanotube mixed solution was cooled to room temperature, diluted with deionized water, filtered, washed with deionized water until pH=7, and ultrasonically treated with an ultrasonic disruptor for 0.5 to 2 hours. After ultrasonic treatment, it was freeze-dried at a freezing temperature of -50℃ for 0.5 hours and a drying temperature of -50℃ for 48 hours to obtain short multi-walled carbon nanotubes of different lengths.

[0008] (2) Dissolve the transition metal precursor in a solvent, add short multi-walled carbon nanotubes of different lengths according to the metal loading of 5%-20%, so that the resulting mixed solution is ultrasonically treated at room temperature for 1 hour using an ultrasonic cleaner, stirred at 30-80℃ until completely dry, add 1 mL of solvent again, and stir at 30-80℃ until completely dry.

[0009] (3) The material obtained in step (2) is oxidized at a specific oxidation temperature of 5-10℃ / min under an argon atmosphere. The obtained material is quickly rinsed with 2M dilute nitric acid, then rinsed with deionized water, dried at room temperature, and then reduced to a specific reduction temperature of 5-10℃ / min under a 10% argon-hydrogen mixed atmosphere to obtain a carbon nanotube confined transition metal hydrogenation catalyst.

[0010] In the above-mentioned method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, it is optional that the reaction temperature of the mixed acid of 65% concentrated nitric acid and 98% concentrated sulfuric acid with 2μm multi-walled carbon nanotubes is 80-110℃ and the reaction time is 20-60min.

[0011] In the above-mentioned method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, it is optional that the volume ratio of 2μm multi-walled carbon nanotubes to a mixed acid of 65% concentrated nitric acid and 98% concentrated sulfuric acid is 0.5g:90-200mL.

[0012] In the above-mentioned method for preparing high-filling-rate carbon nanotube confined hydrogenation catalyst, it is optional that the length of the obtained short multi-walled carbon nanotubes ranges from 100 nm to 2 μm.

[0013] In the above-mentioned method for preparing high-filling-rate carbon nanotube confined hydrogenation catalyst, the metal precursor may be at least one of nickel nitrate hexahydrate, copper nitrate trihydrate, ferric nitrate nonahydrate, nickel iron oleate, and molybdenum naphthenate.

[0014] In the above-mentioned method for preparing high-filling-rate carbon nanotube confined hydrogenation catalyst, the solvent can be at least one of deionized water, anhydrous ethanol, toluene, and acetone.

[0015] In the above-mentioned method for preparing the high-filling-rate carbon nanotube confined hydrogenation catalyst, the specific oxidation temperature can be 400-500℃ when the metal is iron; 400-500℃ when the metal is nickel; 200-400℃ when the metal is copper; and 400-500℃ when the metal is molybdenum.

[0016] In the above-mentioned method for preparing the high-filling-rate carbon nanotube confined hydrogenation catalyst, the specific reduction temperature can be 500-600℃ when the metal is iron; 500-600℃ when the metal is nickel; 300-500℃ when the metal is copper; and 400-600℃ when the metal is molybdenum.

[0017] This invention provides a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst. The catalyst support is 100 nm ultrashort multi-walled carbon nanotubes, and the active component is one or more combinations of transition metals such as nickel, copper, and iron. This method is applicable to most transition metals. The preparation method is simple, and the ultrashort multi-walled carbon nanotubes significantly improve the internal filling efficiency of the active component, increasing mass transfer efficiency, with an internal filling rate as high as 98.65%. The catalyst exhibits high catalytic efficiency, and the high dispersion of the active component effectively prevents metal active component agglomeration, resulting in nanoclusters. The average particle size of the active component is 5 nm, allowing for control over the particle size. High hydrogen recovery rates are achieved under relatively mild reaction conditions, making it suitable for a wide range of applications. The prepared catalyst is suitable for carbon dioxide hydrogenation and heavy oil hydrogenation processes. The catalyst exposes more active sites, while the protective support ensures high stability of the internal active component, effectively preventing agglomeration and greatly improving catalyst performance.

[0018] The structure of the present invention, as well as its other inventive objects and beneficial effects, will become more apparent from the description of preferred embodiments taken in conjunction with the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Scanning electron microscope (SEM) image of multi-walled carbon nanotubes before treatment in Example 1 of the method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst provided in this invention;

[0021] Figure 2Scanning electron microscope (SEM) image of multi-walled carbon nanotubes after treatment, in Example 1 of the method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst provided in this invention.

[0022] Figure 3 X-ray diffraction pattern of the catalyst prepared in Example 1 of the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst provided in the embodiments of the present invention;

[0023] Figure 4 Transmission electron microscope (TEM) image of the catalyst prepared in Example 1 of the method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst provided in this invention;

[0024] Figure 5 The catalytic performance evaluation results of two catalysts for the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst provided in the embodiments of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in more detail below with reference to the accompanying drawings of the preferred embodiments. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] This invention provides a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, the method comprising:

[0027] (1) 65% concentrated nitric acid and 98% concentrated sulfuric acid were added to a flask at a volume ratio of 1:2 to 4, and a certain amount of 2μm multi-walled carbon nanotubes were added to react and an acidified multi-walled carbon nanotube mixed solution was obtained. The acidified multi-walled carbon nanotube mixed solution was cooled to room temperature, diluted with deionized water, filtered, washed with deionized water until pH=7, and ultrasonically treated with an ultrasonic disruptor for 0.5 to 2 hours. After ultrasonic treatment, it was freeze-dried at a freezing temperature of -50℃ for 0.5 hours and a drying temperature of -50℃ for 48 hours to obtain short multi-walled carbon nanotubes of different lengths.

[0028] (2) Dissolve the transition metal precursor in a solvent, add short multi-walled carbon nanotubes of different lengths obtained in step (1) at a metal loading of 5%-20%, so that the resulting mixed solution is ultrasonically treated at room temperature for 1 hour using an ultrasonic cleaner, stirred at 30-80°C until completely dry, and then 1 mL of solvent is added again and stirred at 30-80°C until completely dry.

[0029] (3) The material obtained in step (2) is oxidized at a specific oxidation temperature of 5-10℃ / min under an argon atmosphere. The obtained material is quickly rinsed with 2M dilute nitric acid, then rinsed with deionized water, dried at room temperature, and then reduced to a specific reduction temperature of 5-10℃ / min under a 10% argon-hydrogen mixed atmosphere to obtain a carbon nanotube confined transition metal hydrogenation catalyst.

[0030] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, the reaction temperature of the mixed acid of 65% concentrated nitric acid and 98% concentrated sulfuric acid with 2μm multi-walled carbon nanotubes in step (1) is 80-110℃, and the reaction time is 20-60min.

[0031] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, in step (1), the volume ratio of 2μm multi-walled carbon nanotubes to 65% concentrated nitric acid and 98% concentrated sulfuric acid is 0.5g:90-200mL.

[0032] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, the length of the short multi-walled carbon nanotubes of different lengths obtained in step (1) is 100 nm to 2 μm.

[0033] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, the metal precursor in step (2) is at least one of nickel nitrate hexahydrate, copper nitrate trihydrate, ferric nitrate nonahydrate, nickel iron oleate, and molybdenum naphthenate.

[0034] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, the solvent in step (2) is at least one of deionized water, anhydrous ethanol, toluene, and acetone.

[0035] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, in step (3), the specific oxidation temperature is 400-500℃ when the metal is iron; the specific oxidation temperature is 400-500℃ when the metal is nickel; the specific oxidation temperature is 200-400℃ when the metal is copper; and the specific oxidation temperature is 400-500℃ when the metal is molybdenum.

[0036] Furthermore, in the preparation method of the high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention, in step (3), the specific reduction temperature is 500-600℃ when the metal is iron; the specific reduction temperature is 500-600℃ when the metal is nickel; the specific reduction temperature is 300-500℃ when the metal is copper; and the specific reduction temperature is 500-600℃ when the metal is molybdenum.

[0037] This invention provides a method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst. The catalyst support is 100 nm ultrashort multi-walled carbon nanotubes, and the active component is one or more combinations of transition metals such as nickel, copper, and iron. This method is applicable to most transition metals. The preparation method is simple. The ultrashort multi-walled carbon nanotubes significantly improve the internal filling efficiency of the active component, increasing mass transfer efficiency, with an internal filling rate as high as 98.65%. The catalyst exhibits high catalytic efficiency, and the high dispersion of the active component effectively prevents metal active component agglomeration, resulting in nanoclusters. The average particle size of the active component is 5 nm, allowing for control over the particle size. High hydrogen recovery rates are achieved under relatively mild reaction conditions, making it suitable for a wide range of applications. The prepared catalyst is suitable for carbon dioxide hydrogenation and heavy oil hydrogenation processes. The catalyst exposes more active sites, while the protective support ensures high stability of the internal active component, effectively preventing agglomeration and greatly improving catalyst performance.

[0038] The preparation method of a high-filling-rate carbon nanotube confined hydrogenation catalyst of the present invention will be described in detail below with reference to specific embodiments.

[0039] Example 1

[0040] A method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, wherein the active component of the carbon nanotube confined catalyst prepared by this method is nickel, and the internal filling efficiency of nickel in the catalyst is 98.65%, and the preparation method is as follows:

[0041] (1) Add 30 mL of concentrated nitric acid (wt% = 65%) and 90 mL of concentrated sulfuric acid (wt% = 98%) to a 250 mL round bottom flask, and add 0.5 g of multi-walled carbon nanotubes. Stir the mixture at 110 °C for 40 min, cool and dilute, filter and wash with deionized water until pH = 7, sonicate in an ultrasonic crusher for 2 h and freeze dry to obtain ultrashort multi-walled carbon nanotubes with an average length of 100 nm.

[0042] (2) Dissolve 0.48g of nickel nitrate hexahydrate in 10mL of anhydrous ethanol, add 0.1g of ultrashort multi-walled carbon nanotubes, sonicate for 60min, stir at 30℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 30℃ until completely dry.

[0043] (3) The material obtained in step (2) was oxidized at 400℃ for 2 hours under an argon atmosphere at a heating rate of 5℃ / min. The resulting material was then rapidly washed with 2M dilute nitric acid, followed by rinsing with deionized water. After drying at room temperature, it was reduced at 500℃ under a 10% argon-hydrogen mixed atmosphere at a heating rate of 5℃ / min to obtain an ultrashort carbon nanotube confined nickel metal hydrogenation catalyst (Ni@SCNTs). The Ni metal content of the catalyst was tested, and the internal filling efficiency was found to be 98.65%.

[0044] Figure 1 and Figure 2 These are scanning electron microscope (SEM) images of multi-walled carbon nanotubes before and after treatment in step (1) of Example 1 of this application. Figure 1 It can be seen that the multi-walled carbon nanotubes were cut from the initial 2μm into 100nm ultrashort multi-walled carbon nanotubes.

[0045] The X-ray diffraction pattern of the Ni@CNTs catalyst prepared in Example 1 of this application is shown below. Figure 3 As shown, by Figure 3 As can be seen, the un-acid-washed Ni@CNTs exhibit diffraction peaks of Ni metal and carbon nanotubes, while the acid-washed Ni@CNTs only exhibit diffraction peaks of carbon nanotubes, indicating that the external Ni metal particles were completely washed away after the acid washing step.

[0046] The transmission electron microscope (TEM) image of the Ni@SCNTs prepared in Example 1 of this application is shown below. Figure 4 As shown; by Figure 4 As can be seen, the formed Ni nanoparticles are inside the carbon nanotubes, and there are almost no other nanoparticles attached to the outer surface. The average particle size of the Ni nanoparticles is 5 nm.

[0047] Comparative Examples of Example 1

[0048] Comparative samples of nickel metal hydrogenation catalysts confined in ultrashort carbon nanotubes were prepared. The synthesis method is as follows:

[0049] (1) Dissolve 0.48g of nickel nitrate hexahydrate in 10mL of anhydrous ethanol, add 0.1g of original multi-walled carbon nanotubes, sonicate for 60min, stir at 30℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 30℃ until completely dry.

[0050] (2) The material obtained in step (1) was oxidized at 400℃ for 2 hours under an argon atmosphere at a heating rate of 5℃ / min. The resulting material was then rapidly washed with 2M dilute nitric acid, followed by rinsing with deionized water. After drying at room temperature, it was reduced at 500℃ under a 10% argon-hydrogen mixed atmosphere at a heating rate of 5℃ / min to obtain the original carbon nanotube-confined nickel metal hydrogenation catalyst (Ni@CNTs). The Ni metal content of the catalyst was tested, and the internal filling efficiency was found to be 37.5%.

[0051] Example 2

[0052] A method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, wherein the active component of the carbon nanotube confined catalyst prepared by this method is copper, and the internal filling efficiency of copper in the catalyst is 98.32%, and the preparation method is as follows:

[0053] (1) Add 30 mL of concentrated nitric acid (wt% = 65%) and 90 mL of concentrated sulfuric acid (wt% = 98%) to a 250 mL round-bottom flask, and add 0.5 g of multi-walled carbon nanotubes. Stir the mixture at 110 °C for 60 min, cool and dilute, filter and wash with deionized water until pH = 7, sonicate in an ultrasonic crusher for 2 h and freeze dry to obtain ultrashort multi-walled carbon nanotubes with an average length of 100 nm.

[0054] (2) Dissolve 0.41g of copper nitrate trihydrate in 10mL of anhydrous ethanol, add 0.1g of ultrashort multi-walled carbon nanotubes, sonicate for 60min, stir at 50℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 50℃ until completely dry.

[0055] (3) The material obtained in step (2) was oxidized at 400℃ for 2 hours under an argon atmosphere at a heating rate of 5℃ / min. The resulting material was then rapidly washed with 2M dilute nitric acid, followed by rinsing with deionized water. After drying at room temperature, it was reduced at 500℃ under a 10% argon-hydrogen mixed atmosphere at a heating rate of 5℃ / min to obtain an ultrashort carbon nanotube confined nickel metal hydrogenation catalyst (Ni@SCNTs). The Ni metal content of the catalyst was tested, and the internal filling efficiency was found to be 98.32%.

[0056] Example 3

[0057] A method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, wherein the active components of the carbon nanotube confined catalyst prepared by this method are nickel and copper, and the preparation method is as follows:

[0058] (1) Add 30 mL of concentrated nitric acid (wt% = 65%) and 90 mL of concentrated sulfuric acid (wt% = 98%) to a 250 mL round bottom flask, and add 0.5 g of multi-walled carbon nanotubes. Stir the mixture at 110 °C for 40 min, cool and dilute, filter and wash with deionized water until pH = 7, sonicate in an ultrasonic crusher for 2 h and freeze dry to obtain ultrashort multi-walled carbon nanotubes with an average length of 100 nm.

[0059] (2) Dissolve 0.24g nickel nitrate hexahydrate and 0.21g copper nitrate trihydrate in 10mL of anhydrous ethanol, add 0.1g of ultrashort multi-walled carbon nanotubes, sonicate for 60min, stir at 30℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 30℃ until completely dry.

[0060] (3) The material obtained in step (2) was heated to 400℃ at 5℃ / min for 2h under an argon atmosphere to obtain the oxidized state of the ultrashort carbon nanotube confined nickel-copper alloy hydrogenation catalyst (NiCu@SCNTs).

[0061] Comparative Example 3

[0062] An oxidation-state comparative sample of an ultrashort carbon nanotube-confined nickel-copper alloy hydrogenation catalyst (NiCu@SCNTs) was prepared. The synthesis method is as follows:

[0063] (1) Dissolve 0.24g nickel nitrate hexahydrate and 0.21g copper nitrate trihydrate in 10mL of anhydrous ethanol, add 0.1g of original multi-walled carbon nanotubes, sonicate for 60min, stir at 30℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 30℃ until completely dry.

[0064] (2) The material obtained in step (1) was heated to 400℃ at 5℃ / min under an argon atmosphere for 2h to obtain the original carbon nanotube confined nickel-copper alloy hydrogenation catalyst (NiCu@CNTs) in an oxidized state.

[0065] The oxidation state of the confined catalyst (NiCu@SCNTs) prepared in Example 3 and the comparative sample ((NiCu@CNTs)) in the comparative example of Example 3 were tested for carbon dioxide hydrogenation.

[0066] The experimental steps are as follows:

[0067] 0.1 g of the catalyst to be tested was added to a fixed bed at atmospheric pressure. The catalyst was pretreated with hydrogen at 400 °C for 2 h, then cooled to room temperature. Hydrogen, nitrogen, and carbon dioxide were then introduced in a molar ratio of 3:1:1. The total space velocity was 30 mL / min, the pressure was 3 MPa, and the reactor temperature was raised to 180–320 °C to obtain the reaction product. The product was analyzed by gas chromatography. The catalytic performance evaluation results are shown below. Figure 5 ,Depend on Figure 5 It can be seen that the oxidation state of the confined catalyst (NiCu@SCNTs) prepared in Example 3 is higher than that of the comparative sample ((NiCu@CNTs)) in the comparative example of Example 3.

[0068] Example 4

[0069] A method for preparing a high-filling-rate carbon nanotube confined hydrogenation catalyst, wherein the active components of the carbon nanotube confined catalyst prepared by this method are nickel and iron, and the preparation method is as follows:

[0070] (1) Add 30 mL of concentrated nitric acid (wt% = 65%) and 90 mL of concentrated sulfuric acid (wt% = 98%) to a 250 mL round bottom flask, and add 0.5 g of multi-walled carbon nanotubes. Stir the mixture at 110 °C for 40 min, cool and dilute, filter and wash with deionized water until pH = 7, sonicate in an ultrasonic crusher for 2 h and freeze dry to obtain ultrashort multi-walled carbon nanotubes with an average length of 100 nm.

[0071] (2) Dissolve 0.24g nickel nitrate hexahydrate and 0.46g ferric nitrate nonahydrate in 10mL of anhydrous ethanol, add 0.1g of ultrashort multi-walled carbon nanotubes, sonicate for 60min, stir at 30℃ until completely dry, then add 1mL of anhydrous ethanol again, and stir at 30℃ until completely dry.

[0072] (3) The material obtained in step (2) was heated to 400℃ at 5℃ / min for 2h under an argon atmosphere to obtain the oxidized state of the ultrashort carbon nanotube confined nickel-iron alloy hydrogenation catalyst (NiFe@SCNTS).

[0073] Heavy oil hydrogenation tests were conducted on the confined catalyst (NiFe@SCNTS) prepared in Example 4 under both oxidation and catalyst-free conditions. 450 ppm of the nickel-iron confined catalyst prepared in Example 4 was added to 100 g of Marie residue oil for heavy oil hydrogenation. The results are shown in Table 1. As can be seen from the data in Table 1, the confined catalyst (NiFe@SCNTS) prepared in Example 4 exhibits better performance in its oxidation state.

[0074] Table 1 Distribution of products from the hydrorefining reaction of Marui residue oil

[0075]

[0076]

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high packing rate carbon nanotube confined hydrogenation catalyst, characterized by, The preparation method of the confined hydrogenation catalyst comprises: (1) 65 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid are added to a flask in a volume ratio of 1:2-4, and a certain amount of 2 μm multi-walled carbon nanotubes are added for reaction to obtain an acidified multi-walled carbon nanotube mixed solution; the acidified multi-walled carbon nanotube mixed solution is cooled to room temperature, diluted with deionized water, suction filtered, washed with deionized water until pH=7, and treated with an ultrasonic disrupter for 0.5-2 h; after ultrasonic treatment, it is freeze-dried, the freezing temperature is-50°C, the freezing time is 0.5 h, the drying temperature is-50°C, and the drying time is 48 h to obtain short multi-walled carbon nanotubes of different lengths; wherein the reaction temperature of the mixed acid of 65 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid with 2 μm multi-walled carbon nanotubes is 80-110°C, and the reaction time is 20-60 min; (2) The transition metal precursor is dissolved in a solvent, and the short multi-walled carbon nanotubes of different lengths are added in a metal loading amount of 5%-20%, the obtained mixed solution is treated with an ultrasonic cleaning instrument at room temperature for 1 h, stirred at 30-80°C until completely dry, 1 mL of solvent is added again, and stirred at 30-80°C until completely dry; the metal precursor is at least one of nickel nitrate hexahydrate, copper nitrate trihydrate, and iron nitrate nonahydrate; (3) The material obtained in step (2) is oxidized at a specific oxidation temperature under an argon atmosphere at a rate of 5-10°C / min, the obtained material is quickly washed with 2M dilute nitric acid and then with deionized water, dried at room temperature, and then reduced at a specific reduction temperature under a 10% argon-hydrogen mixed gas atmosphere at a rate of 5-10°C / min to obtain a carbon nanotube confined transition metal hydrogenation catalyst.

2. The method for preparing a high packing density carbon nanotube confined hydrogenation catalyst according to claim 1, characterized by, The mass-volume ratio of 2 μm multi-walled carbon nanotubes to the mixed acid of 65 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid is 0.5 g:90-200 mL.

3. The method of claim 1, wherein the method is characterized by: The length of the obtained short multi-walled carbon nanotubes of different lengths is 100 nm-2 μm.

4. The method of claim 1, wherein the method is characterized by: The solvent is at least one of deionized water, anhydrous ethanol, toluene, and acetone.

5. The method of claim 1, wherein the method is characterized by: When the metal is iron, the specific oxidation temperature is 400-500°C; when the metal is nickel, the specific oxidation temperature is 400-500°C; and when the metal is copper, the specific oxidation temperature is 200-400°C.

6. The method of claim 1, wherein the method is characterized by: When the metal is iron, the specific reduction temperature is 500-600°C; when the metal is nickel, the specific reduction temperature is 500-600°C; and when the metal is copper, the specific reduction temperature is 300-500°C.

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