Aerogel carbon nanotube composite catalyst and preparation method and application thereof

Abstract

The application provides an aerogel carbon nanotube composite catalyst and a preparation method and application thereof. The preparation method of the aerogel carbon nanotube composite catalyst comprises the following steps: placing a metal oxide loaded silica aerogel in a reactor, introducing methane into the reactor, introducing methane after being heated to 710 DEG C, performing a carbonization reaction, and obtaining the aerogel carbon nanotube composite catalyst; in the carbonization reaction, the temperature is 710 DEG C; the specific surface area of the silica aerogel is 600-750 m 2 / g. The preparation method can prepare the aerogel carbon nanotube composite catalyst with excellent stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, and in particular to an aerogel carbon nanotube composite catalyst, its preparation method, and its application. Background Technology

[0002] Ethanol, as a basic chemical raw material, has its downstream high-value-added conversion being an important direction for extending the coal chemical industry chain. Currently, my country has achieved industrialization breakthroughs in coal-to-ethanol technology, but further high-value utilization of ethanol still faces bottlenecks. Higher alcohols (C3-C6 alcohols), as key intermediates in the fine chemical industry, are widely used in plasticizers, surfactants, detergents, and pharmaceuticals. However, traditional higher alcohol production mainly relies on the hydroformylation of higher olefins or the hydrogenation of oils and fats, which suffers from high costs and unstable raw material supply, making large-scale production difficult.

[0003] In the catalytic conversion of ethanol to higher alcohols, catalyst performance directly affects reaction efficiency and product selectivity. During the preparation of higher alcohols, existing catalysts are prone to metal sintering or carbon deposition, leading to catalyst deactivation and insufficient ethanol conversion efficiency.

[0004] Therefore, it is necessary to develop a catalyst with excellent stability, which will become a key technological breakthrough for achieving efficient conversion of ethanol into higher alcohols. Summary of the Invention

[0005] This invention provides a method for preparing an aerogel carbon nanotube composite catalyst, which can produce an aerogel carbon nanotube composite catalyst with excellent stability.

[0006] This invention provides an aerogel-carbon nanotube composite catalyst, which exhibits excellent stability.

[0007] This invention provides a method for preparing higher alcohols, which can improve the conversion rate of raw materials and the selectivity of higher alcohols.

[0008] The first aspect of the present invention provides a method for preparing an aerogel-carbon nanotube composite catalyst, comprising:

[0009] A silica aerogel loaded with metal oxides was placed in a reactor, and methane was introduced into the reactor. The temperature was raised to 710°C and methane was introduced again to carry out a carbonization reaction, thereby obtaining an aerogel-carbon nanotube composite catalyst.

[0010] The specific surface area of ​​the silica aerogel is 600~750m². 2 / g.

[0011] The preparation method of the aerogel carbon nanotube composite catalyst as described above further includes introducing nitrogen gas into the reactor before introducing methane into the reactor.

[0012] In the preparation method of the aerogel carbon nanotube composite catalyst as described above, the mass percentage of the metal oxide in the silica aerogel loaded with metal oxide is 2-5%.

[0013] The preparation method of the aerogel carbon nanotube composite catalyst as described above, wherein the mass of the silica aerogel loaded with metal oxide is 2.0 g;

[0014] After introducing methane into the reactor, the temperature is maintained at 710°C for 1-3 hours, and then nitrogen is introduced into the reactor to obtain the aerogel carbon nanotube composite catalyst.

[0015] The preparation method of the aerogel carbon nanotube composite catalyst as described above, wherein the silica aerogel loaded with metal oxide is obtained by sequentially subjecting raw materials including silica aerogel and metal source to ultrasonic impregnation, drying and calcination.

[0016] In the preparation method of the aerogel carbon nanotube composite catalyst described above, the metal source is nickel acetylacetone.

[0017] In the preparation method of the aerogel carbon nanotube composite catalyst as described above, the ultrasonic impregnation treatment is performed with a power of 500W for 2 hours.

[0018] A second aspect of the present invention provides an aerogel carbon nanotube composite catalyst, wherein the catalyst is prepared using the preparation method described above.

[0019] A third aspect of the present invention provides a method for preparing a higher alcohol, wherein the above-mentioned aerogel carbon nanotube composite catalyst is used to catalyze anhydrous ethanol to obtain the higher alcohol.

[0020] The higher alcohol has ≥3 carbon atoms.

[0021] In the method for preparing higher alcohols as described above, the catalytic reaction is carried out at a temperature of 175-190°C for a time of 10-15 hours; and / or,

[0022] The mass of the aerogel carbon nanotube composite catalyst is 1 to 3% of the mass of the anhydrous ethanol.

[0023] This invention involves placing silica aerogel loaded with metal oxides in a reactor and introducing methane, then carrying out a carbonization reaction at 710°C. The silica aerogel has a specific surface area of ​​600-750 m². 2 / g, can form an aerogel carbon nanotube composite catalyst on a high specific surface area aerogel framework, which improves the stability of the catalyst, and the metal elements can be uniformly dispersed in the silica aerogel, so that the catalyst has excellent catalytic activity; when the above aerogel carbon nanotube composite catalyst is used to catalyze the conversion of ethanol to higher alcohols, the conversion rate of ethanol and the selectivity of higher alcohols can be improved. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] In existing technologies, the catalytic conversion of ethanol to higher alcohols is inefficient and lacks selectivity, mainly due to the tendency of existing catalysts' metal active centers to aggregate and exhibit low dispersion during catalysis, resulting in low catalytic efficiency per unit catalyst. The inventors discovered that by designing a composite catalyst based on silica aerogel-supported metal oxides and in-situ grown carbon nanotubes, the stability of the catalyst can be improved, thus solving the technical challenge of efficiently converting ethanol to higher alcohols.

[0026] The first aspect of the present invention provides a method for preparing an aerogel-carbon nanotube composite catalyst, comprising:

[0027] A silica aerogel loaded with metal oxides was placed in a reactor, and methane was introduced into the reactor. The temperature was raised to 710°C and methane was introduced again to carry out a carbonization reaction, thus obtaining an aerogel-carbon nanotube composite catalyst.

[0028] The specific surface area of ​​silica aerogel is 600~750m². 2 / g.

[0029] Specifically, methane has reducing properties. In the reactor, metal oxides are reduced to metal nanoparticles. Some of the metal nanoparticles can act as catalysts for decomposing methane. Under the combined action of metal nanoparticles and high temperature (710℃), methane is decomposed into carbon nanotubes, which are deposited on the surface of silica aerogel to obtain an aerogel-carbon nanotube composite catalyst.

[0030] In the preparation method of the aerogel-carbon nanotube composite catalyst of the present invention, the specific surface area of ​​the silica aerogel is 600~750 m². 2When the carbonization reaction temperature is 710℃, carbon nanotubes can be uniformly deposited on the surface of silica aerogel, resulting in carbon nanotubes with uniform diameter and few surface defects. Simultaneously, metal nanoparticles can be uniformly dispersed within the silica aerogel. For example, the specific surface area of ​​the silica aerogel can be 600 m². 2 / g、650 m 2 / g、700 m 2 / g、750 m 2 A range consisting of any one of / g or any two of them.

[0031] When the aerogel-carbon nanotube composite catalyst of the present invention is used for the catalytic reaction of ethanol to higher alcohols, the metal nanoparticles can serve as the active component, activating ethanol as an intermediate in the catalytic reaction. Since the metal nanoparticles are uniformly dispersed in the silica aerogel, the catalyst has high catalytic activity and can prevent the metal nanoparticles from sintering and agglomerating. At the same time, the excellent stability of carbon nanotubes and silica aerogel can give the catalyst high structural stability. The catalyst still has excellent catalytic activity during repeated use, thus extending the service life of the catalyst.

[0032] Furthermore, the synergistic effect of carbon nanotubes and metal nanoparticles enhances the catalytic efficiency of metal nanoparticles through the electronic effect of carbon nanotubes, while suppressing the ethanol dehydration side reaction, thereby improving the conversion rate of ethanol and the selectivity of higher alcohols, and realizing the efficient conversion of ethanol to higher alcohols.

[0033] In existing technologies, the catalytic conversion of ethanol to higher alcohols at low temperatures (<200°C) is inefficient and has poor selectivity. This is mainly due to the insufficient activity of traditional metal catalysts at low temperatures, requiring high temperatures (>200°C) to achieve higher ethanol conversion rates. However, high temperatures easily trigger ethanol dehydration side reactions, leading to an increase in byproducts such as ethylene. In some embodiments, when using the aerogel-carbon nanotube composite catalyst of the present invention to catalyze the conversion of ethanol to higher alcohols, efficient conversion of ethanol can be achieved at low temperatures (<200°C), improving the conversion rate of ethanol and the selectivity of higher alcohols with low energy consumption.

[0034] The present invention does not impose any particular limitation on the preparation method of silica aerogel, and can use any method commonly used in the art for preparing silica aerogel.

[0035] In some embodiments of the present invention, nitrogen gas is introduced into the reactor before methane is introduced into the reactor.

[0036] When methane is directly introduced into a tubular reactor, due to the presence of oxygen, some of the methane is converted into carbon oxides, such as CO and CO2, instead of carbon nanotubes. Only after the oxygen has completely reacted can the methane be converted into carbon nanotubes. This results in resource waste, and the prepared aerogel-carbon nanotube composite catalyst contains impurities, which is detrimental to subsequent catalytic reactions.

[0037] Nitrogen is an inert protective gas. When nitrogen is introduced into the reactor, it can replace the residual air, oxygen and moisture in the reactor, thereby preventing methane from coming into contact with oxygen during the heating and initial stage of the reaction and causing side reactions. This not only saves the amount of methane used, but also allows the carbonization reaction to take place under low-interference and high-safety atmospheric conditions, maintaining the stability of the silica aerogel framework, and enabling the carbon atoms generated by methane cracking to be directionally deposited and construct a composite conductive network, thus obtaining an aerogel carbon nanotube composite catalyst with uniform structure and stable interfacial bonding.

[0038] Introducing nitrogen into the reactor followed by methane can rapidly reduce metal oxides to elemental metals, thereby catalyzing methane cracking, promoting the growth of carbon nanotubes on the surface of the silica aerogel framework, and simultaneously inhibiting insufficient methane cracking due to insufficient temperature and side reactions caused by excessively high temperature.

[0039] In some embodiments of the present invention, when the mass percentage of metal oxide in the silica aerogel loaded with metal oxide is 2-5%, a sufficient number of metal active sites can be constructed while maintaining the high specific surface area and open pore structure of the silica aerogel. On the one hand, this can improve the efficiency of methane cracking and carbon nanotube deposition in the subsequent carbonization reaction, and on the other hand, it can prevent the metal elements from sintering. This makes it easier to form an aerogel-carbon nanotube composite catalyst with uniform metal element distribution in the carbonization reaction, thereby improving the stability and reusability of the aerogel-carbon nanotube composite catalyst.

[0040] Furthermore, the metal elements within the aforementioned mass percentage range ensure that the aerogel-carbon nanotube composite catalyst possesses sufficient metal active centers, resulting in superior catalytic activity. For example, the mass percentage of the metal oxide can be any one of 2%, 3%, 4%, or 5%, or a combination of any two thereof.

[0041] In some embodiments of the present invention, the mass of the silica aerogel loaded with metal oxide is 2.0 g. After methane is introduced into the reactor, it is kept at 710°C for 1-3 hours, and then nitrogen is introduced into the reactor to obtain the aerogel-carbon nanotube composite catalyst. By controlling the holding time, the amount of methane introduced can be controlled, thereby controlling the production of carbon nanotubes. When the holding time is 1-3 hours, the silica aerogel and methane can be better matched, ensuring continuous generation of carbon nanotubes while maintaining the unobstructed pores of the silica aerogel. Subsequently, nitrogen is introduced into the reactor to replace residual methane and a small amount of byproducts generated by the carbonization reaction with the inert atmosphere of nitrogen, and to protect and cool the high-temperature reaction system, thereby terminating the carbonization reaction and stabilizing the structure of the obtained aerogel-carbon nanotube composite catalyst. Through the above process, a uniformly dispersed carbon nanotube network can be constructed in the silica aerogel framework, giving the aerogel-carbon nanotube composite catalyst both excellent mass transfer capacity and structural stability.

[0042] For example, after methane is introduced into the reactor, the holding time can be selected from any one of 1h, 1.5h, 2h, 2.5h, 3h, or any combination thereof.

[0043] In some embodiments of the present invention, silica aerogel loaded with metal oxide is obtained by sequentially subjecting raw materials including silica aerogel and metal source to ultrasonic impregnation, drying, and calcination.

[0044] Specifically, silica aerogel is a carrier material with a three-dimensional porous framework structure. In ultrasonic impregnation, metal ions from the metal source are loaded onto the surface and / or pores of the silica aerogel. The ultrasonic cavitation effect enhances the wetting and diffusion capacity of the internal pores of the silica aerogel to the metal source, allowing the metal ions to enter the silica aerogel framework more uniformly. The drying process removes volatile components after ultrasonic impregnation and stabilizes the distribution of metal elements in the silica aerogel. In the calcination process, the metal ions undergo an oxidation reaction, forming metal oxides that exist on the surface and / or in the pores of the silica aerogel.

[0045] Since silica aerogel has a high specific surface area and abundant pore structure, the above-mentioned combination of ultrasonic impregnation, drying and calcination can enhance the bonding stability between metal elements and silica aerogel, thus providing a structural basis for the construction of aerogel carbon nanotube composite catalysts in subsequent carbonization reactions.

[0046] In some embodiments, prior to drying, the silica aerogel impregnated with the metal source is washed with deionized water and then filtered.

[0047] This invention does not limit the temperature and time of the calcination process, as long as it ensures that the metal ions can be fully oxidized into metal oxides.

[0048] This invention does not impose a particular limitation on the metal source, and it can be any compound containing a metal element commonly used in the art. Exemplarily, the metal source can be at least one of nickel nitrate, nickel acetate, and nickel acetylacetonate. Further, in some embodiments of this invention, the metal source is nickel acetylacetonate.

[0049] Nickel acetylacetone has good organic coordination stability and solubility, which can keep nickel ions in a uniform and stable state in the impregnation solution, thereby reducing the probability of local precipitation and aggregation of nickel ions in silica aerogel, which is beneficial to improving the uniformity of metal oxide distribution on the carrier surface.

[0050] In some embodiments of the present invention, during ultrasonic impregnation treatment, when the power is 500W and the time is 2h, metal ions can be more uniformly loaded on the surface and / or channels of silica aerogel, thereby forming metal oxides with excellent dispersion during subsequent calcination treatment, which is beneficial to improving the catalytic activity of aerogel carbon nanotube composite catalyst.

[0051] A second aspect of the present invention provides an aerogel-carbon nanotube composite catalyst, prepared using the above-described preparation method. This aerogel-carbon nanotube composite catalyst exhibits excellent catalytic activity and stability. When used in the catalytic reaction of ethanol to higher alcohols, it can extend the catalyst's lifespan while improving the ethanol conversion rate and the selectivity of higher alcohols.

[0052] A third aspect of the present invention provides a method for preparing higher alcohols, wherein the above-mentioned aerogel carbon nanotube composite catalyst is used to catalyze the reaction of anhydrous ethanol to obtain higher alcohols.

[0053] Higher alcohols have ≥3 carbon atoms.

[0054] Specifically, under the action of a catalyst, ethanol first removes hydrogen from its hydroxyl group to form acetaldehyde. Two molecules of acetaldehyde undergo addition and dehydration to obtain an unsaturated aldehyde with a high carbon number. At the same time, the hydrogen removed from ethanol reacts with the unsaturated aldehyde to form a higher alcohol.

[0055] In this invention, the silica aerogel in the aerogel-carbon nanotube composite catalyst possesses a high specific surface area and porous structure, providing a uniform loading environment for the metal element. In the catalytic reaction, the metal element acts as the active center, catalyzing the dehydrogenation of ethanol. The carbon nanotubes enhance the activity of the metal element through electronic effects, simultaneously improving the stability of the aerogel-carbon nanotube composite catalyst and suppressing side reactions such as ethanol dehydration. The silica aerogel ensures the uniform dispersion of the metal element within the catalyst, reducing the probability of catalyst deactivation. The synergistic effect of silica aerogel, metal element, and carbon nanotubes endows the catalyst with both high catalytic activity and long-term operational stability, thereby improving the conversion rate of ethanol and the yield of higher alcohols.

[0056] Furthermore, the preparation method of the present invention does not require frequent catalyst replacement, thus exhibiting excellent economic efficiency.

[0057] In some embodiments of the present invention, when the temperature is 175-190°C and the time is 10-15 hours during the catalytic reaction, ethanol can be efficiently converted under energy-saving conditions. Furthermore, the above-mentioned temperature can reduce the probability of side reactions occurring during the catalytic reaction and improve the selectivity of higher alcohols. Exemplarily, in the catalytic reaction, the temperature can be any one of 175°C, 180°C, 185°C, and 190°C, or any combination thereof; the time can be any one of 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, and 15 hours, or any combination thereof.

[0058] In some embodiments of the present invention, the mass of the aerogel-carbon nanotube composite catalyst is 1-3% of the mass of anhydrous ethanol, which enables the ethanol to be fully activated while saving costs and improving the conversion rate of ethanol. Exemplarily, the mass of the aerogel-carbon nanotube composite catalyst can be any of 1%, 1.5%, 2%, 2.5%, 3% of the mass of anhydrous ethanol, or any combination thereof.

[0059] In some embodiments, the method for preparing higher alcohols of the present invention can achieve an ethanol conversion rate of 47.2% and a higher alcohol selectivity of greater than 99%.

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0061] Example 1

[0062] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment includes the following steps:

[0063] (1) Preparation of silica aerogel

[0064] 3 mL of tetramethyl orthosilicate, 1 mL of 3-aminopropyltrimethoxysilane, and 5 mL of methanol were mixed and stirred at 30 °C for 15 min. Then, 3 mL of methanol was added dropwise, and stirring continued until turbidity was observed. After cooling, a gel was formed. The gel was aged for 5 h, and then an equal volume of methanol was added for two solvent exchanges. Then, an equal volume of tetraethyl orthosilicate was added for two more solvent exchanges, each lasting 12 h, to obtain the aerogel precursor. The aerogel precursor was dried sequentially at 40 °C for 3 h, 50 °C for 3 h, and 70 °C for 24 h, followed by heat treatment to obtain silica aerogel. The specific surface area of ​​the silica aerogel was 689.3 m². 2 / g.

[0065] (2) Preparation of aerogel-carbon nanotube composite catalyst

[0066] 0.275g of nickel acetylacetonate was weighed and added to deionized water. After stirring and dissolving, an impregnation solution was obtained. 2g of the above-mentioned silica aerogel was added to the impregnation solution, and ultrasonic impregnation was performed for 2 hours at an ultrasonic power of 500W. After filtration and washing, the solution was dried and then calcined at 530℃ for 3 hours to obtain silica aerogel loaded with nickel oxide. The mass percentage of nickel oxide was 4%.

[0067] The silica aerogel loaded with nickel oxide was placed on a quartz distribution plate of a tubular reaction tube. The tubular reaction tube was then placed in a heating furnace. Nitrogen gas was introduced into the tubular reaction tube to fully replace the air. Methane was then introduced, and the furnace was heated to 710°C. After the temperature stabilized, methane was continued to be introduced. The temperature was maintained for 2 hours, and then nitrogen gas was introduced. The furnace temperature was then lowered to 25°C to obtain the aerogel carbon nanotube composite catalyst.

[0068] Example 2

[0069] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0070] In the nickel-loaded silica aerogel, the mass percentage of nickel oxide is 2%.

[0071] Example 3

[0072] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0073] In the nickel-loaded silica aerogel, the mass percentage of nickel oxide is 3%.

[0074] Example 4

[0075] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0076] In the nickel-loaded silica aerogel, the mass percentage of nickel oxide is 5%.

[0077] Example 5

[0078] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0079] (1) Preparation of silica aerogel

[0080] The aerogel precursor was dried sequentially at 40℃ for 3 h, 50℃ for 3 h, and 70℃ for 12 h, followed by heat treatment to obtain silica aerogel; the specific surface area of ​​the silica aerogel was 736 m². 2 / g.

[0081] Example 6

[0082] The preparation method of the aerogel-carbon nanotube composite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0083] (2) Preparation of aerogel-carbon nanotube composite catalyst

[0084] The furnace is heated to 710°C. After the temperature stabilizes, methane is introduced and the furnace is kept at this temperature for 1 hour before nitrogen is introduced.

[0085] Comparative Example 1

[0086] The catalyst in this comparative example is silica aerogel without supported metal oxides. The preparation methods for the silica aerogel and the higher alcohols are the same as in Example 1.

[0087] Comparative Example 2

[0088] This comparative example uses commercially available multi-walled carbon nanotubes (30~100nm in diameter) as a catalyst.

[0089] Comparative Example 3

[0090] The catalyst in this comparative example is silica aerogel supported on a metal oxide, wherein the metal oxide is nickel oxide, and the mass percentage of nickel oxide is 4%. The remaining steps are the same as in Example 1.

[0091] Comparative Example 4

[0092] This comparative example uses commercially available multi-walled carbon nanotubes (30~100nm in diameter) as a carrier, and then uses the same loading method as in Example 1 to load nickel oxide with a mass percentage of 4% in the multi-walled carbon nanotubes.

[0093] Comparative Example 5

[0094] This comparative example directly uses nickel oxide as a catalyst.

[0095] Test case

[0096] The catalysts used in the above examples and comparative examples were used to carry out the catalytic reaction of ethanol to higher alcohols. The specific steps are as follows:

[0097] Add 2g of anhydrous ethanol to the reaction vessel, add the catalyst, seal the reaction vessel, and then fully replace the air with nitrogen. Next, heat the reaction vessel to carry out the catalytic reaction. After the reaction is completed, cool to obtain the reaction product including higher alcohols.

[0098] The catalytic reaction conditions are shown in Table 1. The amount of catalyst added is the mass percentage of anhydrous ethanol, expressed in wt%.

[0099] Performance testing

[0100] After the catalytic reaction is complete, the reaction product is removed from the reactor, the catalyst is filtered, and the test solution is obtained. A quantitative amount of the test solution is taken, methanol is added as solvent, and the mixture is stirred evenly. The test solution is analyzed by gas chromatography, and the chromatographic data are quantified using the internal standard method. Then, the conversion rate of ethanol and the selectivity of higher alcohols are calculated using the following formulas.

[0101] Ethanol conversion rate = (concentration of ethanol in raw material - concentration of ethanol in product) / concentration of ethanol in raw material × 100%.

[0102] Selectivity of higher alcohols = concentration of higher alcohols / (concentration of ethanol in feedstock - concentration of ethanol in product) × 100%.

[0103] The results of the performance tests are shown in Table 1.

[0104] Table 1

[0105]

[0106] As shown in Table 1, the ethanol conversion rate and the selectivity of higher alcohols in Examples 1-6 are greater than those in Comparative Examples 1-5. This is because the examples used aerogel-carbon nanotube composite catalysts, which allow metal elements to be uniformly loaded on the surface and / or pores of silica aerogel, giving the catalyst excellent catalytic activity. Furthermore, carbon nanotubes can enhance the electron conduction capacity of the catalyst, improving the efficiency of the catalytic reaction. At the same time, the aerogel-carbon nanotube composite catalyst also has excellent stability, maintaining excellent catalytic activity even under long-term catalytic action, resulting in a high ethanol conversion rate in the catalytic reaction.

[0107] Furthermore, all of the above catalytic reactions were carried out at temperatures below 200°C. The aerogel carbon nanotube composite catalyst can still maintain excellent catalytic activity at low temperatures. Low temperatures can reduce the probability of side reactions, thereby improving the selectivity of higher alcohols.

[0108] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for preparing an aerogel-carbon nanotube composite catalyst, characterized in that, include: A silica aerogel loaded with metal oxides was placed in a reactor, and methane was introduced into the reactor. The temperature was raised to 710°C and methane was introduced again to carry out a carbonization reaction, thereby obtaining an aerogel-carbon nanotube composite catalyst. The specific surface area of ​​the silica aerogel is 600~750m². 2 / g.

2. The preparation method of the aerogel-carbon nanotube composite catalyst according to claim 1, characterized in that, Before introducing methane into the reactor, nitrogen gas is also introduced into the reactor.

3. The method for preparing the aerogel-carbon nanotube composite catalyst according to claim 1 or 2, characterized in that, In the silica aerogel loaded with metal oxides, the mass percentage of metal oxides is 2-5%.

4. The method for preparing the aerogel-carbon nanotube composite catalyst according to any one of claims 1-3, characterized in that, The mass of the silica aerogel loaded with metal oxide is 2.0 g; After introducing methane into the reactor, the temperature is maintained at 710°C for 1-3 hours, and then nitrogen is introduced into the reactor to obtain the aerogel carbon nanotube composite catalyst.

5. The method for preparing the aerogel-carbon nanotube composite catalyst according to any one of claims 1-4, characterized in that, The silica aerogel loaded with metal oxides is obtained by sequentially subjecting raw materials, including silica aerogel and a metal source, to ultrasonic impregnation, drying, and calcination.

6. The method for preparing the aerogel-carbon nanotube composite catalyst according to claim 5, characterized in that, The metal source is nickel acetylacetone.

7. The method for preparing the aerogel-carbon nanotube composite catalyst according to claim 5 or 6, characterized in that, In the ultrasonic impregnation treatment, the power is 500W and the time is 2h.

8. An aerogel-carbon nanotube composite catalyst, characterized in that, It was prepared using the preparation method described in any one of claims 1-7.

9. A method for preparing higher alcohols, characterized in that, The higher alcohol was obtained by catalytic reaction of anhydrous ethanol using the aerogel carbon nanotube composite catalyst according to claim 8. The higher alcohol has ≥3 carbon atoms.

10. The method for preparing higher alcohols according to claim 9, characterized in that, In the catalytic reaction, the temperature is 175~190℃ and the time is 10~15h; and / or, The mass of the aerogel carbon nanotube composite catalyst is 1 to 3% of the mass of the anhydrous ethanol.

Images