Catalyst as well as preparation method and application thereof

Abstract

The invention provides a catalyst as well as a preparation method and application thereof. The catalyst comprises the following components in percentage by mass: 4-6% of vanadium carbide, 9-11% of nickel element and the balance of titanium dioxide. According to the catalyst provided by the invention, vanadium carbide is introduced as an auxiliary agent, so that the growth of nickel microcrystals and the agglomeration of nickel particles can be inhibited, and the dispersity of metal nickel can be improved, so that the catalytic activity of the catalyst can be improved, the regeneration capacity of the catalyst can be improved, and the conversion rate of methane and the hydrogen production rate can be improved when methane is cracked to generate hydrogen.

Description

Technical Field

[0001] The invention belongs to the field of material technology, and in particular relates to a catalyst and a preparation method and application thereof. Background Art

[0002] As a clean and efficient energy source, the development and application of hydrogen energy is of great significance for reducing greenhouse gas emissions and promoting energy transformation. As an important hydrogen production technology, catalytic methane cracking (CMD) has attracted much attention because it can produce high-purity hydrogen without additional purification steps and its by-product is carbon materials with commercial value.

[0003] Methane catalytic cracking technology mainly depends on the performance of the catalyst. At present, commonly used catalysts include carbon-based catalysts and metal catalysts. Carbon-based catalysts have high thermal stability and sulfur resistance, but their catalytic activity is low; metal catalysts, especially nickel-based catalysts, have become a hot topic of research due to their high activity. However, the metal particles in the metal catalysts are not stable, which affects the activity of the catalyst, and the regeneration ability of the metal catalyst is poor, which limits its recycling. Therefore, the development of a catalyst with high catalytic activity and strong regeneration ability is a technical problem that needs to be solved in this field. Summary of the invention

[0004] The main purpose of the present invention is to provide a catalyst with high catalytic activity and strong regeneration ability, thereby improving the conversion rate of methane and the hydrogen production rate.

[0005] The present invention also provides a method for preparing a catalyst, which can prepare the above catalyst with simple process and low cost.

[0006] The present invention also provides a method for generating hydrogen by cracking methane, which is obtained by catalytically cracking methane using the above catalyst, thereby improving the conversion rate of methane and the hydrogen production rate.

[0007] In a first aspect, the present invention provides a catalyst, which comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the remainder titanium dioxide.

[0008] The catalyst as described above comprises, by mass percentage, 5% vanadium carbide, 10% nickel element, and the remainder titanium dioxide.

[0009] The catalyst as described above has a specific surface area of ​​133.7-174.8 m 2 / g, the pore volume is 1.07-1.38mL / g, and the average pore diameter is 21-26nm.

[0010] The catalyst as described above is prepared by a method comprising the following process:

[0011] The titanium dioxide is impregnated with an aqueous solution comprising a nickel source and vanadium carbide, and the impregnation system is subjected to post-treatment including rotary evaporation, drying and grinding to obtain the catalyst.

[0012] In a second aspect, the present invention provides a method for preparing the catalyst as described above, comprising the following steps:

[0013] 1) mixing vanadium carbide powder and nickel salt solution to obtain a mixed solution;

[0014] 2) impregnating the mixed solution with titanium dioxide to obtain an impregnation system;

[0015] 3) The impregnation system is subjected to rotary evaporation treatment, drying treatment and grinding treatment in sequence to obtain the catalyst.

[0016] The method for preparing the catalyst as described above, wherein the temperature of the rotary evaporation treatment is 70-90°C;

[0017] And / or, the drying treatment is carried out at a temperature of 90-110° C. and for a time of 5-8 hours.

[0018] In a third aspect, the present invention provides a method for generating hydrogen by cracking methane, which is obtained by catalytic cracking of methane using the catalyst as described above or the catalyst obtained by the preparation method as described above.

[0019] The method as described above, wherein the method for generating hydrogen by cracking methane comprises the following steps:

[0020] 1) subjecting the catalyst to an activation treatment under the protection of an inert gas to obtain an activated catalyst;

[0021] 2) At a temperature of 500-600° C. and a pressure of 0.8-1.0 MPa, methane is introduced into a reactor fixed with the activated catalyst to carry out a gas-solid contact reaction to obtain the hydrogen.

[0022] In the method as described above, the activation treatment is carried out at a temperature of 550-600° C. and for a time of 2-4 hours.

[0023] The method as described above further comprises: regenerating the catalyst after the reaction using carbon dioxide.

[0024] The catalyst provided by the present invention can inhibit the growth of nickel crystallites and the agglomeration of nickel particles by introducing vanadium carbide as an auxiliary agent, thereby improving the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst and its regeneration ability, and when methane is cracked to generate hydrogen, the conversion rate of methane and the hydrogen production rate can be increased. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In a first aspect, the present invention provides a catalyst, which comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the remainder titanium dioxide.

[0027] The catalyst provided by the present invention comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the balance is titanium dioxide. Nickel element, as an active metal in the catalyst, has high catalytic activity and can effectively promote the breaking of carbon-hydrogen bonds in methane molecules to generate hydrogen and carbon; the introduction of vanadium carbide can inhibit the growth of nickel crystallites in the process of catalytic methane cracking, maintain the active surface area of ​​the catalyst, thereby improving the catalytic activity of the catalyst. In addition, the introduction of vanadium carbide can also inhibit the growth and agglomeration of nickel particles, maintain the active structure of the catalyst, thereby extending the service life of the catalyst. Therefore, when the catalyst comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the balance is titanium dioxide, the catalyst has high catalytic activity and stability, can achieve efficient methane cracking reaction at a lower temperature, improve the conversion rate of methane and the hydrogen production rate, and help reduce energy consumption and production costs, and improve economic benefits. When the mass percentage of vanadium carbide in the catalyst is not within 4-6%, and / or the mass percentage of nickel is not within 9-11%, the catalyst cannot play such a role, and thus cannot catalyze the cracking of methane to generate hydrogen or when methane is cracked to generate hydrogen, the methane conversion rate is low and the hydrogen production rate is low.

[0028] Compared with other precious metal catalysts, nickel and titanium dioxide are relatively cheap and easily available, making the catalyst cost-effective in industrial production.

[0029] The catalyst provided by the present invention can inhibit the growth of nickel crystallites and the agglomeration of nickel particles by introducing vanadium carbide as an auxiliary agent, thereby improving the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst and its regeneration ability, and when methane is cracked to generate hydrogen, the conversion rate of methane and the hydrogen production rate can be increased.

[0030] In some embodiments of the present invention, the catalyst comprises, by mass percentage, 5% vanadium carbide, 10% nickel element, and the remainder is titanium dioxide.

[0031] The catalyst of the present invention comprises, by mass percentage, 5% vanadium carbide, 10% nickel, and the remainder titanium dioxide. As a preferred solution, the catalytic activity and regeneration ability of the catalyst can be further improved. In the process of using the catalyst to catalyze the cracking of methane to generate hydrogen, the conversion rate of methane and the hydrogen production rate can be further improved. In particular, under the reaction conditions of 500°C, 10% Ni-5% VC / TiO 2 The catalyst exhibited high methane conversion and hydrogen production rates, indicating its great potential in industrial applications.

[0032] In some embodiments of the present invention, the specific surface area of ​​the catalyst is 133.7-174.8 m 2 / g, the pore volume is 1.07-1.38mL / g, and the average pore diameter is 21-26nm.

[0033] The specific surface area of ​​the samples was calculated using the BET (Brunauer-Emmett-Teller) method, and the pore structure data of the samples were analyzed using the desorption curve and the Barrett-Joyner-Halenda (BJH) method.

[0034] The specific surface area of ​​the catalyst in the present invention is 133.7-174.8m 2 / g, pore volume is 1.07-1.38mL / g, and average pore diameter is 21-26nm. In a suitable range, the contact area between the reactant and the catalyst can be suitable. The catalyst has a large number of active sites, which can significantly improve the speed and efficiency of the catalytic reaction. The appropriate pore volume of the catalyst can ensure that there is enough space for the reactant molecules to enter the pores and contact the active sites, and prevent the pores from being too large, resulting in reduced selectivity. The appropriate average pore diameter of the catalyst makes the catalyst suitable for small molecule reactions and prevents large molecules from blocking the pores, thereby improving the stability of the catalyst and thus increasing the service life of the catalyst.

[0035] The catalyst of the present invention has H 2 The hysteresis loop is a mesoporous material with a cylindrical pore structure and a specific surface area of ​​133.7-174.8m 2 / g, the pore volume is 1.07-1.38mL / g, and the average pore diameter is 21-26nm, which is in a suitable range, which helps to improve the adsorption and dispersibility of metallic nickel. Therefore, the catalyst has high reaction activity, can improve the methane conversion rate and hydrogen production rate in the methane cracking reaction, and can also increase the service life of the catalyst.

[0036] In some embodiments of the present invention, the catalyst is prepared by a method comprising the following process:

[0037] The titanium dioxide is impregnated with an aqueous solution comprising a nickel source and vanadium carbide, and the impregnation system is subjected to post-treatment including rotary evaporation, drying and grinding to obtain the catalyst.

[0038] In one embodiment, a nickel salt can be dissolved in water to form a nickel salt solution, and then a certain mass of vanadium carbide powder is slowly added to the nickel salt solution and stirred until completely dispersed to obtain an aqueous solution including a nickel source and vanadium carbide. A certain amount of nano titanium dioxide is added to the above aqueous solution, and the solution is stirred and impregnated for a certain period of time at room temperature so that the vanadium carbide and the nickel salt are evenly dispersed on the titanium dioxide carrier to obtain an impregnation system. The impregnation system is placed in a rotary evaporator to evaporate and remove the solvent, and then transferred to an oven for drying, and then ground into powder to obtain the catalyst, wherein the catalyst includes, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the remainder is titanium dioxide.

[0039] The method for preparing the catalyst of the present invention can prepare the catalyst of the first aspect of the present invention, avoiding an additional reduction step, and has a simple process and low cost.

[0040] In a second aspect, the present invention provides a method for preparing the catalyst as described above, comprising the following steps:

[0041] 1) mixing vanadium carbide powder and nickel salt solution to obtain a mixed solution;

[0042] 2) impregnating the mixed solution with titanium dioxide to obtain an impregnation system;

[0043] 3) The impregnation system is subjected to rotary evaporation treatment, drying treatment and grinding treatment in sequence to obtain the catalyst.

[0044] The present invention uses a mixed solution including vanadium carbide and nickel salt to impregnate the carrier titanium dioxide to obtain an impregnation system, and then performs post-treatment on the impregnation system to obtain the catalyst of the first aspect of the present invention.

[0045] Specifically, in step 1), a nickel salt, for example, Ni(NO 3 ) 2 6H 2 O is dissolved in a proper amount of deionized water to form a nickel salt solution, and then the vanadium carbide powder is slowly added to the nickel salt solution and stirred at room temperature for a certain time, for example, 24 hours, to obtain a mixed solution.

[0046] In step 2), a certain amount of carrier titanium dioxide is slowly added to the mixed solution obtained above, and stirring and impregnation are continued for a certain time, for example, 24 hours, so that the metal nickel and vanadium carbide are evenly dispersed and adsorbed on the carrier titanium dioxide to obtain an impregnation system.

[0047] In step 3), the impregnation system obtained above is post-treated, that is, rotary evaporation, drying and grinding are performed in sequence to obtain the catalyst of the first aspect of the present invention, that is, the catalyst comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the balance is titanium dioxide. The rotary evaporation can be performed in a rotary evaporator to evaporate and remove water; the drying can be performed in an oven to further remove water and volatile substances in the impregnation system.

[0048] The method for preparing the catalyst of the present invention can prepare the catalyst of the first aspect of the present invention, avoids the additional reduction step, improves the preparation efficiency, simplifies the production process of the catalyst, reduces the cost, and maintains the high activity and stability of the catalyst, which is of great significance for large-scale production and industrial application.

[0049] In some embodiments of the present invention, the temperature of the rotary evaporation treatment is 70-90°C;

[0050] And / or, the drying treatment is carried out at a temperature of 90-110° C. and for a time of 5-8 hours.

[0051] The temperature of the rotary evaporation treatment is limited to a suitable range in the present invention, and the solvent can be effectively removed while maintaining the stability of the active components of the catalyst. The temperature and time of the drying treatment are within a suitable range, and the drying treatment can completely remove the moisture and volatile substances in the catalyst, which helps the catalyst to form a stable crystal structure, optimizes the catalyst structure, and improves the catalytic activity and stability of the catalyst, thereby improving the conversion rate of methane and the hydrogen production rate in the methane cracking reaction.

[0052] In a third aspect, the present invention provides a method for generating hydrogen by cracking methane, which is obtained by catalytic cracking of methane using the catalyst as described above or the catalyst obtained by the preparation method as described above.

[0053] The present invention utilizes the catalyst provided in the first aspect or the catalyst prepared by the preparation method provided in the second aspect to catalytically crack methane to generate hydrogen, thereby improving the conversion rate of methane and the hydrogen production rate.

[0054] In some embodiments of the present invention, the method for generating hydrogen by cracking methane comprises the following steps:

[0055] 1) subjecting the catalyst to an activation treatment under the protection of an inert gas to obtain an activated catalyst;

[0056] 2) At a temperature of 500-600° C. and a pressure of 0.8-1.0 MPa, methane is introduced into a reactor fixed with the activated catalyst to carry out a gas-solid contact reaction to obtain the hydrogen.

[0057] In the present invention, the catalyst is firstly activated under the protection of an inert gas to obtain an activated catalyst, and then the activated catalyst is used to carry out a gas-solid contact reaction on methane to obtain hydrogen.

[0058] Specifically, in step 1), the catalyst is activated under an inert gas, such as nitrogen, to obtain an activated catalyst. It is understood that after the catalyst is prepared, it is often necessary to activate it so that the passive catalyst is converted into an activated catalyst. The purpose of activation is to form active sites required for the catalytic reaction on the catalyst, especially on the catalyst surface.

[0059] In step 2), the temperature of the reactor fixed with the activated catalyst is maintained in the range of 500-600°C and the pressure is maintained in the range of 0.8-1.0MPa, and then methane is introduced into the reactor to react with the catalyst in a gas-solid contact manner. Under the action of the catalyst, the carbon-hydrogen bonds in the methane are broken to generate hydrogen and carbon. 2 The catalyst showed excellent methane conversion rate and hydrogen production rate. At this temperature, the catalyst not only showed good stability, but also achieved high methane conversion rate and hydrogen production rate, which is of great significance for improving hydrogen production efficiency, reducing energy consumption and improving the economic benefits of the entire methane catalytic cracking process.

[0060] The present invention uses the titanium dioxide loaded with vanadium carbide and metallic nickel as a catalyst, which can catalyze the cracking of methane to generate hydrogen. The catalyst has high activity and strong regeneration ability, so the conversion rate of methane and the hydrogen production rate can be improved.

[0061] In some embodiments of the present invention, the activation treatment is performed at a temperature of 550-600° C. for a time of 2-4 hours.

[0062] The temperature and time of the activation treatment of the catalyst in the present invention are both within a suitable range, and various pollutants present on the catalyst surface, such as organic pollutants, sulfides, nitrides and phosphides, etc., can be eliminated, and these pollutants usually reduce the activity of the catalyst. Through high-temperature treatment, the adsorbed molecules on the catalyst surface and the impurities on the carrier will be separated from the catalyst surface, thereby restoring the active center on the catalyst surface, improving its catalytic activity, and also improving the anti-sintering ability of the catalyst, preventing the catalyst particles from sticking together at high temperatures, maintaining its good dispersibility and pore structure, and improving the service life of the catalyst. When the catalyst catalyzes the cracking of methane to generate hydrogen, the conversion rate of methane and the hydrogen production rate can be improved.

[0063] In some embodiments of the present invention, the process further comprises: regenerating the catalyst after the reaction using carbon dioxide.

[0064] The present invention regenerates the catalyst after the reaction with carbon dioxide, which can restore the catalytic activity of the catalyst, extend the service life of the catalyst, and reduce the frequency of replacement due to catalyst deactivation, thereby reducing production costs and saving waste of raw materials and energy, which is of great significance to improving overall economic efficiency.

[0065] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0066] Example 1

[0067] The method for generating hydrogen by cracking methane in this embodiment comprises the following steps:

[0068] 1) Take 49.58g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 5 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution;

[0069] 2) Slowly add 2g of nano-TiO 2 , continue stirring and impregnating for 24 hours to obtain an impregnation system;

[0070] 3) The impregnation system was evaporated in a rotary evaporator at 80° C. for 5 h to remove water, and then dried in an oven at 100° C. for 6 h, and the catalyst was obtained after grinding;

[0071] 4) subjecting the above catalyst to activation treatment at 550° C. for 2 h under nitrogen protection to obtain an activated catalyst;

[0072] 5) adjusting the temperature of the reactor fixed with the activated catalyst to 600° C. and the pressure to 0.9 MPa, and introducing methane to obtain hydrogen;

[0073] 6) The catalyst involved in the above reaction was recovered, and CO at a flow rate of 50 mL / min was introduced into the catalyst at a temperature of 300 °C. 2 , N with a flow rate of 40 mL / min 2 The mixture was activated for 30 min; then it was placed in a fixed bed reactor and nitrogen was introduced at room temperature and pressure for 2 h at a flow rate of 100 mL / min; then a mixture of hydrogen and nitrogen was introduced, the temperature was set at 450 ° C, the flow rate was 50 mL / min, and the reduction was carried out for 2 h to obtain a recovered catalyst.

[0074] Example 2

[0075] The method for generating hydrogen by cracking methane in Example 2 is basically the same as that in Example 1, except that in step 1), 44.62 g Ni(NO 3 )2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 5 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0076] Example 3

[0077] The method for generating hydrogen by cracking methane in Example 3 is basically the same as that in Example 1, except that in step 1), 54.54 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 5 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0078] Example 4

[0079] The method for generating hydrogen by cracking methane in Example 4 is basically the same as that in Example 1, except that in step 1), 49.58 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 3 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0080] Example 5

[0081] The method for generating hydrogen by cracking methane in Example 5 is basically the same as that in Example 1, except that in step 1), 49.58 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 4 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0082] Example 6

[0083] The method for generating hydrogen by cracking methane in Example 6 is basically the same as that in Example 1, except that in step 1), 49.58 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 6 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0084] Example 7

[0085] The method of generating hydrogen by cracking methane in Example 7 is basically the same as that in Example 1, except that the drying temperature is changed to 110° C. See Table 1 for specific parameters.

[0086] Example 8

[0087] The method of generating hydrogen by cracking methane in Example 8 is basically the same as that in Example 1, except that the drying time is changed to 8 hours. Specific parameters are shown in Table 1.

[0088] Example 9

[0089] The method of generating hydrogen by cracking methane in Example 9 is basically the same as that in Example 1, except that the temperature of the activation treatment is changed to 600° C. Specific parameters are shown in Table 1.

[0090] Example 10

[0091] The method of generating hydrogen by cracking methane in Example 10 is basically the same as that in Example 1, except that the activation treatment time is changed to 4 hours. Specific parameters are shown in Table 1.

[0092] Embodiment 11

[0093] The method for generating hydrogen by cracking methane in Example 11 is basically the same as that in Example 1, except that the reaction temperature of the catalytic cracking of methane is changed to 500° C. Specific parameters are shown in Table 1.

[0094] Example 12

[0095] The method for generating hydrogen by cracking methane in Example 12 is basically the same as that in Example 1, except that the reaction pressure of catalytic cracking of methane is changed to 0.8 MPa. Specific parameters are shown in Table 1.

[0096] Example 13

[0097] The method for generating hydrogen by cracking methane in Example 13 is basically the same as that in Example 1, except that the reaction pressure of catalytic cracking of methane is changed to 1.0 MPa. Specific parameters are shown in Table 1.

[0098] Comparative Example 1

[0099] The method for generating hydrogen by cracking methane in Comparative Example 1 is basically the same as that in Example 1, except that in step 1), 24.79 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 5 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0100] Comparative Example 2

[0101] Comparative Example 2 is basically the same as the method for generating hydrogen by cracking methane in Example 1, except that in step 1), 99.16 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 5 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0102] Comparative Example 3

[0103] Comparative Example 3 is basically the same as the method for generating hydrogen by cracking methane in Example 1, except that in step 1), 49.58 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 1 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0104] Comparative Example 4

[0105] Comparative Example 4 is basically the same as the method for generating hydrogen by cracking methane in Example 1, except that in step 1), 49.58 g Ni(NO 3 )2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution, 10 g of VC powder was slowly added to the nickel salt solution, and stirred at room temperature for 24 h to obtain a mixed solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0106] Comparative Example 5

[0107] Comparative Example 5 is basically the same as the method for generating hydrogen by cracking methane in Example 1, except that in step 1), 49.58 g Ni(NO 3 ) 2 6H 2 O was dissolved in 25 mL of deionized water to form a nickel salt solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0108] Comparative Example 6

[0109] Comparative Example 6 is basically the same as the method for generating hydrogen by cracking methane in Example 1, except that in step 1), 5 g of VC powder is dissolved in 25 mL of deionized water to form a vanadium carbide solution; in step 2), 2 g of nano-TiO 2 , and continue stirring and impregnating for 24 hours to obtain an impregnation system. Specific parameters are shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, compared with the comparative example, the catalyst provided by the present invention can inhibit the growth of nickel crystallites and the agglomeration of nickel particles by introducing vanadium carbide as an auxiliary agent, thereby improving the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, improving its regeneration ability, and improving the conversion rate of methane and the hydrogen production rate when methane is cracked to generate hydrogen.

[0114] From the comparison between Example 1 and Comparative Examples 1-6, it can be seen that when the catalyst provided by the present invention comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the balance is titanium dioxide, the catalyst has high catalytic activity and stability, can achieve efficient methane cracking reaction at a lower temperature, and improve the methane conversion rate and hydrogen production rate.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 catalyst, characterized in that The catalyst comprises, by mass percentage, 4-6% vanadium carbide, 9-11% nickel element, and the remainder is titanium dioxide.

2. The catalyst according to claim 1, characterized in that The catalyst comprises, by mass percentage, 5% vanadium carbide, 10% nickel element, and the remainder titanium dioxide.

3. The catalyst according to claim 2, characterized in that The specific surface area of ​​the catalyst is 133.7-174.8m 2 / g, the pore volume is 1.07-1.38mL / g, and the average pore diameter is 21-26nm.

4. The catalyst according to any one of claims 1 to 3, characterized in that The catalyst is prepared by a method comprising the following steps: The titanium dioxide is impregnated with an aqueous solution comprising a nickel source and vanadium carbide, and the impregnation system is subjected to post-treatment including rotary evaporation, drying and grinding to obtain the catalyst.

5. A method for preparing the catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) mixing vanadium carbide powder and nickel salt solution to obtain a mixed solution; 2) impregnating the mixed solution with titanium dioxide to obtain an impregnation system; 3) The impregnation system is subjected to rotary evaporation treatment, drying treatment and grinding treatment in sequence to obtain the catalyst.

6. The method for preparing the catalyst according to claim 5, characterized in that: The temperature of the rotary evaporation treatment is 70-90°C; And / or, the drying treatment is carried out at a temperature of 90-110° C. and for a time of 5-8 hours.

7. A method for generating hydrogen by cracking methane, characterized in that: The method is obtained by catalytically cracking methane using the catalyst described in any one of claims 1 to 4 or the catalyst obtained by the preparation method described in claim 5 or 6.

8. The method according to claim 7, characterized in that The method for generating hydrogen by cracking methane comprises the following steps: 1) subjecting the catalyst to an activation treatment under the protection of an inert gas to obtain an activated catalyst; 2) At a temperature of 500-600° C. and a pressure of 0.8-1.0 MPa, methane is introduced into a reactor fixed with the activated catalyst to carry out a gas-solid contact reaction to obtain the hydrogen.

9. The method according to claim 8, characterized in that The activation treatment is carried out at a temperature of 550-600° C. and for a time of 2-4 hours.

10. The method according to claim 9, characterized in that Also includes: The catalyst after the reaction is regenerated using carbon dioxide.

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