A methane carbon dioxide reforming catalyst, a preparation method and application thereof

Abstract

This invention provides a methane-carbon dioxide reforming catalyst, its preparation method, and its application. The methane-carbon dioxide reforming catalyst comprises a composite support and an active component supported on the composite support. The active component comprises 1.0-18.0 wt.% of the total weight of the methane-carbon dioxide reforming catalyst. The composite support comprises acid-modified Y-type molecular sieve and MgO, and the active component comprises Ni. The methane-carbon dioxide reforming catalyst provided by this invention can achieve efficient conversion of methane to carbon dioxide, exhibiting high activity and stability in the methane-carbon dioxide reforming reaction. It provides important technical support for carbon dioxide emission reduction (promoting carbon reduction and efficiency improvement) and syngas production. Furthermore, its preparation method is simple, low-cost, and easy to mass-produce.

Description

Technical Field

[0001] This invention relates to a methane-carbon dioxide reforming catalyst, its preparation method, and its application, belonging to the field of industrial catalysis technology. Background Technology

[0002] The steel and coking industries generate large quantities of coke oven gas, which contains a significant amount of methane. Direct combustion of this gas results in high carbon emissions and low economic value. Meanwhile, achieving carbon dioxide emission reduction and resource utilization is a critical issue that major carbon emitters like the steel and coking industries urgently need to address. Methane reforming with carbon dioxide can produce syngas, which can be used as a reducing gas in metallurgical processes and as a feedstock in chemical processes, showing broad application prospects.

[0003] The reforming reaction of methane and carbon dioxide is a strongly endothermic reaction, and high temperatures are favorable for the conversion of the feed gas. Only at temperatures above 645℃ is the reaction thermodynamically feasible. However, at high temperatures, methane decomposition and carbon monoxide disproportionation easily occur, leading to carbon deposition. This carbon deposition affects the stability of the catalyst, causing it to gradually deactivate. Non-precious metal nickel-based catalysts have activity comparable to precious metal catalysts and have been widely used in methane reforming. However, elemental nickel catalysts are prone to sintering and carbon deposition during reforming, resulting in decreased catalyst activity and stability. Generally, the activity of catalysts can be improved by adding promoters to prepare composite metal catalysts. Cerium oxide can be used as a promoter for nickel-based catalysts, promoting the dispersion of elemental nickel, enhancing the interaction between the active metal and the support, and inhibiting nickel sintering. Furthermore, the strong oxygen storage capacity of cerium oxide also helps to promote the elimination of carbon deposits on the catalyst.

[0004] The following describes some prior art related to this application to enable those skilled in the art to better understand the prior art.

[0005] CN118719123A discloses a nickel-based catalyst, its preparation method, and its application. This nickel-based catalyst is a Ni / CeO2@Silicalite-2 catalyst, which uses Silicalite-2 molecular sieve as a support, with Ni as the active component and a small amount of CeO2 doped. The preparation method of this nickel-based catalyst includes the following specific steps: first, a support with a microporous structure is obtained through a hydrothermal reaction; then, the support, a structure-directing agent, nickel salt, and cerium salt are formulated into a suspension; next, the suspension is subjected to a hydrothermal reaction to obtain a precipitate; finally, the precipitate is pressed, crushed, sieved, dried, calcined, and reduced to obtain the Ni / CeO2@Silicalite-2 catalyst.

[0006] Although the Ni / CeO2@Silicalite-2 catalyst can achieve methane-carbon dioxide reforming at relatively low temperatures with an initial conversion rate of over 90% for both methane and carbon dioxide, the conversion rates decrease significantly with increasing reaction time, such as after 140 hours. Furthermore, the preparation of the catalyst support requires extensive cleaning with deionized water and anhydrous ethanol to ensure the neutrality of the solid product, resulting in high costs and complex operation steps.

[0007] CN119455965A discloses a method for preparing a methane dry reforming catalyst and its application. The preparation method includes: firstly, a 3D-Ti-Ce-O support is prepared by precipitation method; then, the prepared support is placed in a mixed salt solution of nickel salt, iron salt and niobium salt by impregnation method; finally, the impregnated solid is dried and calcined to obtain a Ni-Fe-Nb / 3D-Ti-Ce-O catalyst.

[0008] Although the Ni-Fe-Nb / 3D-Ti-Ce-O catalyst can achieve room temperature and atmospheric pressure catalytic reforming of methane and carbon dioxide under plasma discharge, the results of the embodiments show that the single-pass conversion rate of methane and carbon dioxide is limited and the stability needs to be improved. Its industrial application still needs to be investigated.

[0009] Therefore, researching, developing, and providing a methane-carbon dioxide reforming catalyst, its preparation method, and its application to achieve efficient conversion of methane into carbon dioxide, and to ensure that the catalyst exhibits high activity and stability in the reforming reaction, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0010] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a methane-carbon dioxide reforming catalyst, its preparation method, and its applications. This invention at least solves the technical problems of low activity, low conversion rate, and poor stability of existing methane-carbon dioxide reforming catalysts.

[0011] To achieve the above objectives, in one aspect, the present invention provides a methane-carbon dioxide reforming catalyst, wherein the methane-carbon dioxide reforming catalyst comprises a composite support and an active component supported on the composite support, wherein, based on 100% of the total weight of the methane-carbon dioxide reforming catalyst, the content of the active component is 1.0-18.0 wt.%, preferably 5.0-12.0 wt.%; the composite support comprises acid-modified Y-type molecular sieves and MgO, etc., and the active component comprises Ni, etc.

[0012] As a specific embodiment of the methane-carbon dioxide reforming catalyst described above in this invention, the methane-carbon dioxide reforming catalyst further includes an auxiliary agent supported on the composite support, the auxiliary agent including CeO2, etc., and the content of the auxiliary agent, calculated as metal, is 5.0-10.0 wt. based on 100% of the total weight of the methane-carbon dioxide reforming catalyst.

[0013] In the methane-carbon dioxide reforming catalyst of the present invention, the addition of the promoter Ce can form cerium oxide (CeO2) after activation, which has good oxygen storage and metal valence change effects. It can eliminate the carbon deposits generated in the methane-carbon dioxide reforming process, reduce the coating of catalytic active sites by carbon deposits, promote the dispersion of metal active sites, and improve the catalyst's anti-carbon deposit and anti-sintering performance, thus promoting the improvement of activity and stability.

[0014] In a specific embodiment of the methane-carbon dioxide reforming catalyst described above in this invention, the content of MgO is 20.0-60.0 wt., based on the total weight of the composite support as 100%.

[0015] In a specific embodiment of the methane-carbon dioxide reforming catalyst described above in this invention, the acid-modified Y-type molecular sieve includes acid-modified HY molecular sieve and / or USY molecular sieve, etc.

[0016] In a specific embodiment of the methane-carbon dioxide reforming catalyst described above in this invention, the acid solution used in the acid modification treatment includes one of hydrochloric acid, nitric acid, sulfuric acid, etc., and preferably, the acid solution is nitric acid.

[0017] In this invention, acid modification of Y-type molecular sieve can adjust the silicon-to-aluminum ratio of Y-type molecular sieve, thereby adjusting the number of acid centers in Y-type molecular sieve, and can also create pores in the Y-type molecular sieve body, adjusting the specific surface area and pore structure of the composite carrier.

[0018] In the composite support of the methane-carbon dioxide reforming catalyst described above in this invention, part of the magnesium oxide is loaded on the acid-modified Y-type molecular sieve body, and part of the magnesium oxide is free outside the acid-modified Y-type molecular sieve body; part of the active component is loaded on the surface and pores of the acid-modified Y-type molecular sieve, part of the active component is loaded on the surface of magnesium oxide, and part of the active component combines with magnesium oxide to form a spinel structure.

[0019] Furthermore, the magnesium oxide in the composite support of the methane-carbon dioxide reforming catalyst described above in this invention does not have a porous structure.

[0020] On the other hand, the present invention also provides a method for preparing the above-described methane-carbon dioxide reforming catalyst, wherein the preparation method includes: Step (1): Mix magnesium salt and acid-modified Y-type molecular sieve in water until uniform, then add ammonia solution to obtain a mixture. Heat the mixture until magnesium ions are completely precipitated, then let it stand for a period of time to obtain a suspension. Filter, wash, dry and calcine the suspension in sequence to obtain a composite carrier. Step (2): The composite carrier and the nickel salt aqueous solution are mixed and heated so that the nickel ions in the nickel salt aqueous solution are impregnated onto the composite carrier; Step (3): Add alkali solution to the suspension obtained in step (2) and heat it. Then filter, dry and calcine to obtain the catalyst precursor. Step (4): The catalyst precursor is activated in a hydrogen / nitrogen mixed atmosphere to obtain the methane carbon dioxide reforming catalyst.

[0021] In one specific embodiment of the preparation method described above in this invention, in step (1), the magnesium salt and the acid-modified Y-type molecular sieve are added together to water and mixed evenly by stirring. This invention does not impose specific requirements on the water used; it can be selected reasonably as needed. In some specific embodiments of this invention, the water used may be, for example, deionized water.

[0022] As a specific embodiment of the preparation method described above in this invention, in step (1), the magnesium salt includes one or a combination of several of magnesium nitrate hydrate, magnesium chloride hydrate, and magnesium acetate.

[0023] As a specific embodiment of the preparation method described above in this invention, in step (1), the concentration of the ammonia solution is 0.1-0.5 mol / L; And / or, the heating is performed in a water bath at 40-60°C for 4-10 hours; And / or, the aging and standing period is 10-18 hours at room temperature; And / or, step (1) further includes grinding the composite carrier to below 200 mesh and storing it in a dryer for later use.

[0024] In some specific embodiments of the present invention, the water bath in step (1) can be carried out in a water bath. Furthermore, the present invention does not specify the specific operations and process parameters for filtration, washing, drying, and calcination performed in step (1) to prepare the composite carrier; these can be reasonably selected and adjusted as needed, as long as the composite carrier can be obtained.

[0025] As a specific embodiment of the preparation method described above in this invention, in step (1), the preparation method of the acid-modified Y-type molecular sieve includes: The Y-type molecular sieve is calcined to remove the template agent. The calcined Y-type molecular sieve is then mixed with an acid solution to obtain a suspension. The suspension is heated to a target temperature and then stirred. Finally, it is filtered, washed, and dried to obtain the acid-modified Y-type molecular sieve.

[0026] As a specific embodiment of the preparation method described above in this invention, the calcination temperature is 500-600℃ when preparing the acid-modified Y-type molecular sieve; And / or, the concentration of the acid solution is 0.4-1.2 mol / L, preferably 0.8-1.0 mol / L; And / or, the heating is to 35-65°C, preferably 40-50°C, and the stirring time is 2-10 hours, preferably 6-8 hours.

[0027] As a specific embodiment of the preparation method described above in this invention, when preparing the acid-modified Y-type molecular sieve, the calcined Y-type molecular sieve is added to an acid solution and the two are mixed to obtain a suspension.

[0028] As a specific embodiment of the preparation method described above in this invention, in step (2), the composite carrier is added to the nickel salt aqueous solution and stirred and heated under water bath conditions so that the nickel ions in the nickel salt aqueous solution are impregnated onto the composite carrier.

[0029] As a specific embodiment of the preparation method described above in this invention, when the methane-carbon dioxide reforming catalyst further includes an auxiliary agent supported on the composite support, in step (1), the composite support and the mixed aqueous solution of nickel salt and cerium salt are mixed and heated to impregnate the nickel ions and cerium ions in the mixed aqueous solution of nickel salt and cerium salt onto the composite support. Preferably, the composite support is added to the mixed aqueous solution of nickel salt and cerium salt and stirred and heated under water bath conditions to impregnate the nickel ions and cerium ions in the mixed aqueous solution of nickel salt and cerium salt onto the composite support. Furthermore, the nickel salt aqueous solution and the mixed aqueous solution of nickel salt and cerium salt can be prepared using conventional methods. For example, a certain amount of nickel salt is weighed as needed and added to deionized water to obtain a nickel salt aqueous solution. A certain amount of nickel salt and cerium salt are weighed as needed and added to deionized water to obtain a mixed aqueous solution of nickel salt and cerium salt.

[0030] The cerium salt is a trivalent cerium salt. This invention does not specify the exact substances used for the nickel salt and trivalent cerium salt, and they can be reasonably selected and adjusted as needed. In some embodiments of this invention, the trivalent cerium salt may be, for example, cerium nitrate hexahydrate, and the nickel salt may be, for example, nickel nitrate hexahydrate.

[0031] As a specific embodiment of the preparation method described above in this invention, in step (2), the immersion temperature, that is, the target temperature to which it is heated, is 40-60°C, preferably 45°C, and the time is 4-8h.

[0032] In a specific embodiment of the preparation method described above in this invention, in step (3), an alkaline solution is added to the suspension obtained in step (2) and the mixture is heated and stirred to allow for slow precipitation. This slow precipitation process ensures that the metal ions are precipitated relatively uniformly and finely on the surface and pores of the Y-type molecular sieve, or on the surface of magnesium oxide (in addition, some metal ions will combine with magnesium oxide to form a spinel structure). After precipitation, the mixture is filtered, dried, and calcined, then pressed into tablets and sieved to obtain the catalyst precursor.

[0033] As a specific embodiment of the preparation method described above in this invention, in step (3), the alkaline solution includes an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide, etc. And / or, the addition is by dropping, at a rate of 0.1-1.0 mL / min, preferably 0.3-0.5 mL / min; And / or, the heating temperature is 40-60℃, and the time is 4-8h; And / or, the calcination temperature is 700-1000℃; And / or, the catalyst precursor has a mesh size of 40-60 mesh.

[0034] In some specific embodiments of the present invention, an alkaline solution may be added dropwise to the suspension obtained in step (2) using a peristaltic pump.

[0035] As a specific embodiment of the preparation method described above in this invention, in step (4), the activation temperature is 700-1000℃ and the time is 4-10h; And / or, in a hydrogen / nitrogen mixed atmosphere, the volume flow ratio of hydrogen to nitrogen is 5:1 to 1:1.

[0036] In step (4) of the preparation method described above, the efficiency of heat transfer can be controlled by adjusting the flow rate of carrier nitrogen, so as to transfer heat out while ensuring the completion of activation, thereby reducing the impact of activation on the catalyst structure.

[0037] In one specific embodiment of the preparation method described above, the preparation method further includes drying the composite carrier before step (2), that is, the composite carrier needs to be dried before impregnation, and the drying temperature is 90-120℃ for 4-6 hours. In some specific embodiments of the present invention, the drying can be carried out in an oven.

[0038] In another aspect, the present invention also provides the application of the above-described methane-carbon dioxide reforming catalyst in the catalytic reforming of methane-carbon dioxide to syngas.

[0039] Compared with the prior art, the beneficial technical effects achieved by the present invention include at least the following: This invention provides a methane-carbon dioxide reforming catalyst by supporting active metallic Ni on a composite support of acid-modified Y-type molecular sieve and MgO. This catalyst fully utilizes the acidic centers of the acid-modified Y-type molecular sieve and the basic sites of MgO during the methane-carbon dioxide reforming process, improving the catalyst's activity and stability. It effectively activates methane and adsorbs carbon dioxide, ensuring that the methane cracking rate is comparable to the carbon dioxide cracking rate. Furthermore, compared to a single support, the composite support used in this invention possesses superior pore structure and specific surface area. The composite support optimizes the pore structure and specific surface area of ​​a single support, improving the catalyst's adsorption and diffusion performance, thereby enhancing catalytic activity while maintaining catalyst stability.

[0040] The preparation method of the methane-carbon dioxide reforming catalyst provided by this invention has a simple operation process, a wide range of raw material sources, and mild preparation conditions.

[0041] In summary, the methane-carbon dioxide reforming catalyst provided by this invention can achieve efficient conversion of methane into carbon dioxide, exhibiting high activity and stability in the methane-carbon dioxide reforming reaction. It provides important technical support for carbon dioxide emission reduction (promoting carbon reduction and efficiency improvement) and syngas production. At the same time, its preparation method is simple, low-cost, and easy to mass-produce. Attached Figure Description

[0042] 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 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.

[0043] Figure 1 The methane conversion distribution diagrams are for each methane-carbon dioxide reforming catalyst provided in Examples 1-5 and Comparative Examples 1-3.

[0044] Figure 2 The carbon dioxide conversion rate distribution of each methane-carbon dioxide reforming catalyst provided in Examples 1-5 and Comparative Examples 1-3 is shown in the figure. Detailed Implementation

[0045] It should be noted that the term "comprising" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0046] The "range" disclosed in this invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this way are composable, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is also expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if the listed minimum range values ​​are 1 and 2, and the listed maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0047] In this invention, unless otherwise specified, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this invention, and "0-5" is simply a shortened representation of these numerical combinations.

[0048] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in this invention can be combined with each other to form new technical solutions.

[0049] In this invention, unless otherwise specified, all technical features and preferred features mentioned in this invention can be combined with each other to form new technical solutions.

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments described below are some, but not all, embodiments of this invention, and are only used to illustrate the invention, and should not be considered as limiting the scope of the invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0051] Example 1

[0052] This embodiment provides a methane-carbon dioxide reforming catalyst, which is prepared by a method including the following specific steps: Step (1): Calcine the HY molecular sieve in a muffle furnace at 550℃ in air for 4 hours to remove the template agent, and then allow it to cool naturally to room temperature. Prepare a 0.9 mol / L nitric acid solution, measure 200 mL of the nitric acid solution and pour it into a beaker for later use. Weigh 20 g of the calcined HY molecular sieve and add it to the 200 mL nitric acid solution. Stir at 45℃ for 6 hours. Filter the suspension after stirring and wash it until neutral. Dry the filter cake in an oven at 110℃ for 12 hours. Grind the dried molecular sieve to below 200 mesh using an agate mortar and pestle to obtain the acid-modified HY molecular sieve support (denoted as MHY).

[0053] Step (2): Weigh 64g of magnesium nitrate hexahydrate and 10g of the MHY carrier obtained in step (1) and add them together to deionized water, stirring until evenly mixed. Then add 0.2 mol / L ammonia solution and heat in a water bath at 50℃ for 8 hours until magnesium ions are completely precipitated. Finally, age and stand at room temperature for 12 hours. Filter the aged suspension, wash until neutral, dry at 90℃, and calcine at 600℃ to obtain the composite carrier, denoted as MHY-MgO, in which the mass content of MgO in the composite carrier is 50.0%. Grind the composite carrier to below 200 mesh and store it in a desiccator for later use.

[0054] Step (3): Weigh 4.31g of nickel nitrate hexahydrate and add it to deionized water to prepare a nickel salt solution; weigh 10g of the composite carrier MHY-MgO obtained in step (2) and dry it in an oven at 110℃ for 6h. Then add the composite carrier MHY-MgO to the nickel salt solution and stir and heat it in a water bath at 45℃ for 6h so that the metal ions in the nickel salt solution are impregnated onto the composite carrier MHY-MgO.

[0055] Step (4): Weigh a certain amount of sodium hydroxide to prepare a 0.2 mol / L sodium hydroxide solution. Using a peristaltic pump, add 150 mL of the sodium hydroxide solution dropwise to the suspension obtained in step (3) at a rate of 1.0 mL / min. Continue heating and stirring at 45℃ for 8 hours to allow for slow precipitation. This slow precipitation process ensures that the metal ions are precipitated relatively uniformly and finely on the surface and in the pores of the composite support MHY-MgO. After precipitation, filter, dry (90℃), and calcine (800℃), then press into tablets and sieve to 40-60 mesh to obtain the catalyst precursor.

[0056] Step (5): The catalyst precursor obtained by tableting and sieving is activated at 800℃ in a mixed gas flow of hydrogen (80 mL / min) / nitrogen (20 mL / min) for 8 hours to obtain the methane carbon dioxide reforming catalyst, denoted as Ni / MHY-MgO, with the total weight of Ni / MHY-MgO being 100% and the Ni content being 8.0 wt.%.

[0057] Example 2

[0058] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that the HY molecular sieve in step (1) is replaced with a USY molecular sieve. The methane-carbon dioxide reforming catalyst prepared in this embodiment is denoted as Ni / MUSY-MgO.

[0059] Example 3

[0060] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that 2.42 g of cerium nitrate hexahydrate is additionally added to the nickel salt solution in step (3). The methane-carbon dioxide reforming catalyst prepared in this embodiment is designated as Ni-CeO2 / MHY-MgO, with a Ni content of 7.5 wt.% and a Ce content of 6.7 wt.% based on the total weight of Ni-CeO2 / MHY-MgO as 100%.

[0061] Example 4

[0062] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that the HY molecular sieve in step (1) is replaced with a USY molecular sieve and 2.42 g of cerium nitrate hexahydrate is added to the nickel salt solution in step (3). The methane-carbon dioxide reforming catalyst prepared in this embodiment is designated as Ni-CeO2 / MUSY-MgO. Based on the total weight of Ni-CeO2 / MUSY-MgO as 100%, the Ni content is 7.5 wt.% and the Ce content is 6.7 wt.%.

[0063] Example 5

[0064] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that: the USY molecular sieve is acid-modified to obtain MUSY according to the method in step (1), and the 10g MHY support in step (2) is replaced with 5g MUSY and 5g MHY, and 2.42g of cerium nitrate hexahydrate is added to the nickel salt solution in step (3). The methane-carbon dioxide reforming catalyst prepared in this embodiment is denoted as Ni-CeO2 / MHY-MUSY-MgO. Based on the total weight of Ni-CeO2 / MHY-MUSY-MgO as 100%, the Ni content is 7.5wt.% and the Ce content is 6.7wt.%.

[0065] Example 6

[0066] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that the amount of magnesium nitrate hexahydrate used in step (2) is different, and the mass content of MgO in the composite support obtained in Example 6 is 15.0%.

[0067] Example 7

[0068] This embodiment provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that the amount of magnesium nitrate hexahydrate used in step (2) is different, and the mass content of MgO in the composite support obtained in Example 6 is 65.0%.

[0069] Comparative Example 1

[0070] This comparative example provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that: In steps (2) and (3), 10g of MHY was used to replace the composite support MHY-MgO, and MHY was used as the catalyst support alone. The methane-carbon dioxide reforming catalyst prepared in this comparative example is denoted as Ni / MHY.

[0071] Comparative Example 2

[0072] This comparative example provides a methane-carbon dioxide reforming catalyst, which differs from Example 1 only in that: In step (1), the HY molecular sieve was replaced with a USY molecular sieve. Steps (2) and (3) were omitted, and 10g of MUSY was used to replace the composite support MHY-MgO. MUSY was used as the catalyst support alone. The methane-carbon dioxide reforming catalyst prepared in this comparative example is denoted as Ni / MUSY.

[0073] Comparative Example 3

[0074] This comparative example provides a methane-carbon dioxide reforming catalyst, which is prepared by a method including the following specific steps: Step (1): Weigh 64g of magnesium nitrate hexahydrate and add it to deionized water, stirring until well mixed. Then add 0.2 mol / L ammonia solution and heat in a water bath at 50℃ for 8 hours until magnesium ions are completely precipitated. Finally, let it stand at room temperature for 12 hours, filter and wash the aged suspension until neutral, dry at 90℃ and calcine at 600℃ to obtain MgO support. Grind the MgO support to below 200 mesh and store it in a desiccator for later use.

[0075] Step (2): Weigh 4.31g of nickel nitrate hexahydrate and add it to deionized water to prepare a nickel salt solution; weigh 10g of the MgO support obtained in step (1) and dry it in an oven at 110℃ for 6h. Then add the MgO support to the nickel salt solution and stir and heat it in a water bath at 45℃ for 6h so that the metal ions in the nickel salt solution are impregnated onto the MgO support.

[0076] Step (3): Weigh a certain amount of sodium hydroxide to prepare a 0.2 mol / L sodium hydroxide solution. Using a peristaltic pump, add 150 mL of the sodium hydroxide solution dropwise to the suspension obtained in step (2) at a rate of 1.0 mL / min. Continue heating and stirring at 45℃ for 8 hours to allow for slow precipitation. This slow precipitation process ensures that the metal ions are precipitated relatively uniformly and finely on the MgO support. After precipitation, filter, dry (90℃), and calcine (800℃), then press into tablets and sieve to 40-60 mesh to obtain the catalyst precursor.

[0077] Step (5): The catalyst precursor obtained by tableting and sieving is activated at 800℃ in a mixed gas flow of hydrogen (80 mL / min) / nitrogen (20 mL / min) for 8 hours to obtain the methane carbon dioxide reforming catalyst, denoted as Ni / MgO. The Ni content is 8.0 wt., with the total weight of Ni / MgO being 100%.

[0078] Evaluation of Example 1

[0079] This evaluation example assesses the performance of the methane-carbon dioxide reforming catalysts provided in Examples 1-7 and Comparative Examples 1-3, specifically including: Weigh 0.5 g of each methane-carbon dioxide reforming catalyst and load them into a fixed-bed quartz reactor. Incubate at 800 °C and a space velocity of 24000 mL·g⁻¹. cat -1 ·h -1 The reaction was carried out under a methane-carbon dioxide atmosphere with a volume ratio of 1:1 for 5 hours to investigate the conversion rates of methane and carbon dioxide by various methane-carbon dioxide reforming catalysts. The conversion rates of methane by each catalyst are shown in the figure below. Figure 1As shown, the conversion rates of carbon dioxide to various methane-carbon dioxide reforming catalysts are as follows: Figure 2 As shown.

[0080] from Figure 1 and Figure 2 As can be seen, the methane-carbon dioxide reforming catalysts provided in Examples 1-7 of this invention all exhibit high conversion rates for both methane and carbon dioxide. Furthermore, since the methane-carbon dioxide reforming catalysts provided in Examples 3-5 all contain the promoter CeO2, the conversion rates of methane and carbon dioxide for these three catalysts are higher than those provided in Examples 1, 2, 6, and 7. Additionally, because the MgO content in the composite support of the methane-carbon dioxide reforming catalysts provided in Examples 6 and 7 is not within the range of 20.0-60.0 wt.%, the conversion rates of methane and carbon dioxide for these two catalysts are lower than those provided in Example 1 of this invention.

[0081] from Figure 1 and Figure 2 It can also be seen that the methane-carbon dioxide reforming catalyst provided in Example 1 of the present invention has a higher conversion rate of methane and carbon dioxide than the catalysts provided in Comparative Examples 1-3.

[0082] In addition, from Figure 1 and Figure 2 It can also be seen that during the 5-hour reaction, the conversion rates of methane and carbon dioxide provided by the methane-carbon dioxide reforming catalysts in Examples 1-7 of the present invention did not decrease significantly, while the conversion rates of methane and carbon dioxide provided by Comparative Examples 1-3 decreased significantly. This indicates that the methane-carbon dioxide reforming catalysts provided by the examples of the present invention have excellent stability.

[0083] In summary, the embodiments of this invention provide a methane-carbon dioxide reforming catalyst by supporting active metal Ni on a composite support of acid-modified Y-type molecular sieve and MgO. This catalyst fully utilizes the acidic centers of the acid-modified Y-type molecular sieve and the basic sites of MgO during the methane-carbon dioxide reforming process, improving the catalyst's activity and stability. It effectively activates methane and adsorbs carbon dioxide, ensuring that the methane cracking rate is comparable to the carbon dioxide cracking rate. Furthermore, compared to a single support, the composite support used in this invention has a superior pore structure and specific surface area. The composite support optimizes the pore structure and specific surface area of ​​a single support, improving the catalyst's adsorption and diffusion performance, thereby enhancing catalytic activity while maintaining catalyst stability.

[0084] In the methane-carbon dioxide reforming catalyst provided in this invention, the addition of the promoter Ce can form cerium oxide (CeO2) after activation, which has good oxygen storage and metal valence change effects. It can eliminate the carbon deposits generated during the methane-carbon dioxide reforming process, reduce the coating of catalytic active sites by carbon deposits, promote the dispersion of metal active sites, and improve the catalyst's anti-carbon deposit and anti-sintering performance, thus promoting the improvement of activity and stability.

[0085] The preparation method of the methane-carbon dioxide reforming catalyst provided in this invention has a simple operation process, a wide range of raw material sources, and mild preparation conditions.

[0086] In summary, the methane-carbon dioxide reforming catalyst provided in this embodiment of the invention can achieve efficient conversion of methane into carbon dioxide, exhibiting high activity and stability in the methane-carbon dioxide reforming reaction. It provides important technical support for carbon dioxide emission reduction (promoting carbon reduction and efficiency improvement) and syngas production. At the same time, its preparation method is simple, low-cost, and easy to mass-produce.

[0087] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A methane-carbon dioxide reforming catalyst, characterized in that, The methane-carbon dioxide reforming catalyst comprises a composite support and an active component supported on the composite support, wherein the content of the active component is 1.0-18.0 wt.% based on the total weight of the methane-carbon dioxide reforming catalyst as 100%; the composite support comprises acid-modified Y-type molecular sieve and MgO, and the active component comprises Ni.

2. The methane-carbon dioxide reforming catalyst according to claim 1, characterized in that, The methane-carbon dioxide reforming catalyst further includes an auxiliary agent supported on the composite support, the auxiliary agent comprising CeO2, and the content of the auxiliary agent, calculated as metal, is 5.0-10.0 wt.% based on 100% of the total weight of the methane-carbon dioxide reforming catalyst.

3. The methane-carbon dioxide reforming catalyst according to claim 1 or 2, characterized in that, The MgO content is 20.0-60.0 wt., based on the total weight of the composite carrier as 100%.

4. The methane-carbon dioxide reforming catalyst according to claim 1 or 2, characterized in that, Acid-modified Y-type molecular sieves include acid-modified HY molecular sieves and / or USY molecular sieves.

5. The methane-carbon dioxide reforming catalyst according to claim 1 or 2, characterized in that, The acid solution used in the acid modification treatment includes one of hydrochloric acid, nitric acid, and sulfuric acid.

6. The method for preparing the methane-carbon dioxide reforming catalyst according to any one of claims 1-5, characterized in that, The preparation method includes: Step (1): Mix magnesium salt and acid-modified Y-type molecular sieve in water until uniform, then add ammonia solution to obtain a mixture. Heat the mixture until magnesium ions are completely precipitated, then let it stand for a period of time to obtain a suspension. Filter, wash, dry and calcine the suspension in sequence to obtain a composite carrier. Step (2): The composite carrier and the nickel salt aqueous solution are mixed and heated so that the nickel ions in the nickel salt aqueous solution are impregnated onto the composite carrier; Step (3): Add alkali solution to the suspension obtained in step (2) and heat it. Then filter, dry and calcine to obtain the catalyst precursor. Step (4): The catalyst precursor is activated in a hydrogen / nitrogen mixed atmosphere to obtain the methane carbon dioxide reforming catalyst.

7. The preparation method according to claim 6, characterized in that, In step (1), the concentration of the ammonia solution is 0.1-0.5 mol / L; And / or, the heating is performed in a water bath at 40-60°C for 4-10 hours; And / or, the aging and standing period is 10-18 hours at room temperature; And / or, step (1) further includes grinding the composite carrier to below 200 mesh and storing it in a dryer for later use.

8. The preparation method according to claim 6 or 7, characterized in that, In step (1), the method for preparing the acid-modified Y-type molecular sieve includes: The Y-type molecular sieve is calcined to remove the template agent. The calcined Y-type molecular sieve is then mixed with an acid solution to obtain a suspension. The suspension is heated to a target temperature and then stirred. Finally, it is filtered, washed, and dried to obtain the acid-modified Y-type molecular sieve.

9. The preparation method according to claim 8, characterized in that, The roasting temperature is 500-600℃; And / or, the concentration of the acid solution is 0.4-1.2 mol / L; And / or, the heating is to 35-65°C, and the stirring time is 2-10 hours.

10. The preparation method according to claim 6, characterized in that, In step (1), the composite carrier and the mixed aqueous solution of nickel salt and cerium salt are mixed and then heated so that the nickel ions and cerium ions in the mixed aqueous solution of nickel salt and cerium salt are impregnated onto the composite carrier.

11. The preparation method according to claim 6 or 10, characterized in that, In step (2), the immersion temperature is 40-60℃ and the time is 4-8h.

12. The preparation method according to claim 6 or 7, characterized in that, In step (3), the alkaline solution includes an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide; And / or, the addition is by dropping, at a rate of 0.1-1.0 mL / min; And / or, the heating temperature is 40-60℃, and the time is 4-8h; And / or, the calcination temperature is 700-1000℃; And / or, the catalyst precursor has a mesh size of 40-60 mesh.

13. The preparation method according to claim 6 or 7, characterized in that, In step (4), the activation temperature is 700-1000℃ and the time is 4-10h; And / or, in a hydrogen / nitrogen mixed atmosphere, the volume flow ratio of hydrogen to nitrogen is 5:1 to 1:

1.

14. The preparation method according to claim 6 or 7, characterized in that, The preparation method further includes drying the composite carrier before step (2), wherein the drying temperature is 90-120℃ and the drying time is 4-6h.

15. The use of the methane-carbon dioxide reforming catalyst according to any one of claims 1-5 in the catalytic reforming of methane-carbon dioxide to syngas.

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