Magnesium-aluminum composite oxide carrier and preparation method thereof, and methane dry reforming catalyst and preparation method and application thereof

Abstract

The invention provides a magnesium-aluminum composite oxide carrier and a preparation method thereof as well as a methane dry reforming catalyst and a preparation method and application thereof. The preparation method of the magnesium-aluminum composite oxide carrier comprises the following steps: dissolving magnesium salt in deionized water to form a magnesium salt solution; dissolving an aluminum source in an acid solution to form aluminum sol; mixing the magnesium salt solution and the aluminum sol, adjusting the pH value to 3-4 by using an acid solution, and continuously stirring to obtain a turbid liquid; in the turbid liquid, the molar ratio of aluminum to magnesium is (1: 1)-(3: 1); and drying and roasting the turbid liquid to obtain the magnesium-aluminum composite oxide carrier. The preparation method of the magnesium-aluminum composite oxide carrier is simple in process, environment-friendly and convenient for large-scale production, meanwhile, the obtained carrier has a relatively high specific surface area, and the dispersion degree of active metal nickel can be improved by preparing the supported nickel-based methane dry reforming catalyst by taking the magnesium-aluminum composite oxide as the carrier, so that the grain size of the active metal nickel is reduced, and the catalytic activity of the catalyst is improved. The high-temperature sintering resistance of the catalyst is improved; the activity stability is enhanced.

Description

Technical Field

[0001] This invention relates to a magnesium-aluminum composite oxide support and its preparation method, and a methane dry reforming catalyst and its preparation method and application, belonging to the field of methane dry reforming reaction technology. Background Technology

[0002] Methane is a major component of gases such as natural gas, biogas, coalbed methane, coke oven gas, and shale gas, and is an important energy source as well as a primary raw material for the production of chemical products. However, methane is also a major greenhouse gas, with a stronger greenhouse effect than carbon dioxide. CO2 mainly comes from the use of fossil fuels, such as electricity generation, industrial energy consumption, industrial waste gas emissions, and transportation waste gas emissions, and is a major greenhouse gas. Therefore, reforming these two greenhouse gases into syngas for the production of high-value chemicals has always been a research hotspot. Currently, carbon dioxide emission reduction and recycling technologies have received widespread attention. Methane dry reforming technology can convert methane and CO2 into syngas under the action of a catalyst. On the one hand, it can reduce carbon dioxide emissions from enterprises; on the other hand, it can effectively recover and reuse emitted carbon dioxide. The syngas generated by dry reforming can be further used to produce chemical products such as methanol, acetic acid, and dimethyl ether, or to produce oil products through the Fischer-Tropsch synthesis process. However, this technology has not yet been industrialized, mainly due to the development of dry reforming catalysts.

[0003] In methane dry reforming, nickel-based catalysts have been extensively studied due to their strong methane reactivity, which can fully activate methane. However, this also promotes the dissociation of methane into carbon black or carbon nanotubes, causing carbon deposition on the nickel surface and leading to catalyst deactivation. Furthermore, the high-temperature conditions of methane dry reforming can easily cause sintering and deactivation of the nickel active component. Therefore, developing highly stable methane dry reforming catalysts remains a key research area in this field.

[0004] In catalyst design, the selection and optimization of the support have a significant impact on the stability of nickel-based catalysts. By regulating the structure and properties of the support, the interaction between the active metal and the support, as well as the reducing properties of the metal, can be effectively controlled, thereby preparing nickel-based catalysts with excellent anti-sintering and anti-coking properties at high temperatures. Among them, magnesium-aluminum composite oxide materials have good thermal stability, good hydrothermal resistance, and high mechanical strength, making them an excellent catalyst support, especially suitable for methane dry reforming reaction environments.

[0005] There are many methods for preparing magnesium-aluminum composite oxide materials. Generally, mechanical or chemical methods are first used to mix magnesium and aluminum, and then a spinel structure is generated through a high-temperature solid-state reaction. Specific preparation methods include: high-temperature solid-state reaction, ball milling, urea combustion, co-precipitation, sol-gel method, and hydrothermal synthesis. Among them, the high-temperature solid-state reaction method is similar to the ball milling method. Both methods first use mechanical action to mix magnesium and aluminum sources and then calcine them at high temperature to obtain spinel. However, it is difficult to obtain a single magnesium-aluminum spinel phase in these two methods. They are basically mixed with alumina or magnesium oxide crystal phases. Only by increasing the calcine temperature to above 1300℃ can a single spinel crystal phase be obtained. The urea combustion method also generates spinel crystal phase through instantaneous high-temperature reaction. The instantaneous reaction temperature is as high as 1600℃, which requires high production equipment and the specific surface area and pore size of the obtained spinel products are relatively small. The co-precipitation method, sol-gel method, hydrothermal synthesis method and other production processes are long, have many variable factors, produce a lot of waste liquid, and involve the large-scale use of some organic solvents or surfactants, which is not conducive to the low-cost large-scale production of products. Specifically, regarding the co-precipitation method, CN117000223A discloses a magnesium-aluminum composite oxide support and its preparation method, as well as a methane dry reforming catalyst and its application. The preparation process requires calcining the filter cake obtained by the co-precipitation method at temperatures as high as 1250-1450℃. This high calcination temperature results in the prepared magnesium-aluminum composite oxide support having a specific surface area of ​​only 15-60 m². 2 / g, with a relatively small specific surface area, is not conducive to the dispersion of active components and is prone to sintering of active components at high temperatures.

[0006] In summary, there is a need for a new method for preparing magnesium-aluminum composite oxide materials. The preparation process involves low operating temperature, simple technology, environmental friendliness, and is conducive to large-scale production. Using the prepared magnesium-aluminum composite oxide material as a carrier, a methane dry reforming catalyst with high catalytic activity can be prepared. Summary of the Invention

[0007] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a magnesium-aluminum composite oxide support and its preparation method, as well as a methane dry reforming catalyst and its preparation method and application. The magnesium-aluminum composite oxide support provided by the present invention has a high specific surface area, which is beneficial for the dispersion of active components. Using this magnesium-aluminum composite oxide as a support, a highly active methane dry reforming catalyst can be prepared.

[0008] To achieve the above objectives, on the one hand, the present invention provides a method for preparing a magnesium-aluminum composite oxide carrier, wherein the preparation method includes:

[0009] Step (1): Dissolve the magnesium salt in deionized water to form a magnesium salt solution;

[0010] Step (2): Dissolve the aluminum source in an acid solution to form an aluminum sol;

[0011] Step (3): Mix the magnesium salt solution and aluminum sol and adjust the pH to 3-4 with an acid solution. After continuous stirring, a suspension is obtained. In the suspension, the molar ratio of aluminum to magnesium is 1:1-3:1.

[0012] Step (4): The suspension is dried and calcined to obtain a magnesium-aluminum composite oxide carrier.

[0013] As a specific embodiment of the preparation method described above in this invention, the magnesium salt includes any one or a combination of several of magnesium nitrates, sulfates, chlorides, etc.

[0014] As a specific embodiment of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention, the aluminum source includes any one or a combination of two of boehmite and aluminum hydroxide.

[0015] In one specific embodiment of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention, the acid solution includes any one of nitric acid, sulfuric acid, hydrochloric acid, etc., and the concentration of the acid solution is 0.5-6 mol / L.

[0016] The acid solutions used in steps (2) and (3) of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention can be the same or different, but are preferably the same. Furthermore, the anions in the magnesium salt used in step (1) of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention can be the same or different from the anions in the acid solutions used in steps (2) and / or (3), but are preferably the same. In some preferred embodiments of this invention, the anions in the magnesium salt used in step (1), the anions in the acid solution used in step (2), and the anions in the acid solution used in step (3) are all the same.

[0017] The present invention does not specify the continuous stirring time in step (3) of the preparation method of the magnesium-aluminum composite oxide carrier described above. The continuous stirring time can be reasonably adjusted as needed, as long as the purpose of obtaining a suspension can be achieved. For example, in some embodiments of the present invention, the continuous stirring time is 2 hours.

[0018] In a specific embodiment of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention, the drying temperature is 100-120℃ and the time is 2-10h.

[0019] As a specific embodiment of the preparation method of the magnesium-aluminum composite oxide carrier described above in this invention, the calcination conditions include: air atmosphere, calcination temperature of 700-1100℃ and calcination time of 1-5h.

[0020] On the other hand, the present invention also provides a magnesium-aluminum composite oxide carrier, which is prepared by the above-described method for preparing magnesium-aluminum composite oxide carriers.

[0021] In one specific embodiment of the magnesium-aluminum composite oxide carrier described above in this invention, the specific surface area of ​​the magnesium-aluminum composite oxide carrier is 100-250 m². 2 / g, preferably 150-250m 2 / g, more preferably 200-250m 2 / g, pore volume 0.3-0.8cm 3 / g, with an average pore size of 8-20nm.

[0022] In another aspect, the present invention also provides a methane dry reforming catalyst, comprising a support and an active component supported on the support, wherein the support is the magnesium-aluminum composite oxide support described above, and the active component is nickel;

[0023] The total weight of the methane dry reforming catalyst is 100%, the nickel content is 3-20%, and the balance is the support.

[0024] As a specific embodiment of the methane dry reforming catalyst described above in this invention, the methane dry reforming catalyst further comprises an additive supported on the support, wherein the additive comprises one or a combination of several metals such as sodium, potassium, calcium, strontium, cerium, cobalt, iron, and zirconium.

[0025] The content of the additive, calculated by metal element, is 0.5-20%, wherein the content of the additive is calculated based on the total weight of the methane dry reforming catalyst as 100%.

[0026] Furthermore, the present invention also provides a method for preparing the above-described methane dry reforming catalyst, wherein the preparation method includes:

[0027] The active component metal salt was prepared into an impregnation solution using deionized water. The magnesium-aluminum composite oxide support described above was impregnated with the impregnation solution, then dried and calcined to obtain the methane dry reforming catalyst.

[0028] As a specific embodiment of the preparation method of the methane dry reforming catalyst described above in this invention, when the methane dry reforming catalyst further comprises an auxiliary agent supported on the support, the preparation method further includes: preparing an impregnation solution by mixing the metal salt of the active component and the metal salt of the auxiliary agent with deionized water; impregnating the magnesium-aluminum composite oxide support described above with the impregnation solution, followed by drying and calcination to obtain the methane dry reforming catalyst. This invention does not impose specific requirements on the specific substances of the metal salt of the active component and the metal salt of the auxiliary agent, and they can be reasonably selected as needed. For example, in some embodiments of this invention, the metal salt of the active component can be Ni(NO3)2·6H2O, etc.

[0029] In one specific embodiment of the method for preparing the methane dry reforming catalyst described above in this invention, the drying temperature is 100-120℃ and the drying time is 2-10h.

[0030] And / or the calcination conditions include: air atmosphere, calcination temperature of 400-600℃, and calcination time of 1-5h.

[0031] Finally, the present invention also provides the application of the above-described methane dry reforming catalyst in the catalytic dry reforming reaction of methane to produce syngas, wherein the application includes:

[0032] Methane and CO2 are reacted in a fixed-bed reactor in the presence of the methane dry reforming catalyst to produce syngas. The reaction conditions include: a molar ratio of carbon dioxide to methane of 1-1.2:1, preferably 1-1.1:1; a temperature of 600-950℃, preferably 650-800℃; a pressure of 0-3MPa, preferably 0-1MPa; and a feed gas space velocity of 2000-120000mL / g / h, preferably 60000-120000mL / g / h.

[0033] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0034] The preparation method of the magnesium-aluminum composite oxide support provided by this invention is simple, environmentally friendly, and easy for large-scale production. Compared with the dry mixing method, the liquid-phase preparation method adopted in this invention, which involves preparing magnesium salt solution and aluminum sol separately, mixing them, and then adjusting the pH, drying, and calcining to obtain the magnesium-aluminum composite oxide support, can make the raw materials more uniformly mixed and the resulting support grain size smaller. Therefore, the prepared magnesium-aluminum composite oxide support has a higher specific surface area. Using this magnesium-aluminum composite oxide as a support to prepare a supported nickel-based methane dry reforming catalyst can improve the dispersion of active nickel metal, thereby reducing the grain size of active nickel metal, improving the catalyst's resistance to high-temperature sintering, and enhancing its activity stability. Attached Figure Description

[0035] 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.

[0036] Figure 1 The image shows the XRD pattern of the magnesium-aluminum composite oxide support prepared in Example 1 of this invention.

[0037] Figure 2 The graphs show the performance of the methane dry reforming catalysts provided in Example 1 and Comparative Example 1 of this invention in catalyzing the methane dry reforming reaction. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] In this invention, unless otherwise specified, the term "two kinds" as used in this specification means "at least two kinds".

[0044] In this invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0045] 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.

[0046] Example 1

[0047] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0048] (1) Preparation of magnesium-aluminum composite oxide carrier

[0049] 282 g of Mg(NO3)2·6H2O was weighed and dissolved in 250 mL of deionized water to prepare a magnesium nitrate solution; 86 g of aluminum hydroxide was weighed and dissolved in 2 mol / L nitric acid solution to form an aluminum sol; the magnesium nitrate solution and aluminum sol were mixed and the pH was adjusted to 3 with nitric acid solution, and stirred continuously for 2 h to obtain a suspension; the obtained suspension was dried at 120 °C for 2 h and calcined at 700 °C in air for 4 h to obtain a magnesium-aluminum composite oxide carrier, denoted as MA1, whose specific surface area was measured to be 205 m² by nitrogen adsorption method. 2 / g, pore volume 0.54cm 3 / g, with an average pore size of 14nm. The XRD pattern of this magnesium-aluminum composite oxide support (MA1) is shown below. Figure 1 As shown, a comparison with the standard spectrum reveals that the magnesium-aluminum composite oxide carrier (MA1) has a magnesium-aluminum spinel structure.

[0050] (2) Preparation of methane dry reforming catalyst

[0051] Weigh 9.91g of Ni(NO3)2·6H2O and dissolve it in deionized water to obtain an impregnation solution. Impregnate 20g of the magnesium-aluminum composite oxide support obtained in step (1) in this impregnation solution. After standing for 2 hours, place it in an oven and dry it at 120℃ for 2 hours. Then place the dried sample in a muffle furnace and calcine it at 450℃ for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni / MA1. The content of metallic Ni in Ni / MA1 is 8.9wt%.

[0052] Example 2

[0053] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0054] (1) Preparation of magnesium-aluminum composite oxide carrier

[0055] 180 g of Mg(NO3)2·6H2O was weighed and dissolved in 250 mL of deionized water to prepare a magnesium nitrate solution; 109 g of aluminum hydroxide was weighed and dissolved in 2 mol / L nitric acid solution to form an aluminum sol; the magnesium nitrate solution and aluminum sol were mixed and the pH was adjusted to 3.5 with nitric acid solution, and stirred continuously for 2 h to obtain a suspension; the obtained suspension was dried at 110 °C for 2 h and calcined at 800 °C in air for 4 h to obtain a magnesium-aluminum composite oxide support, denoted as MA2, whose specific surface area was measured to be 223 m² by nitrogen adsorption method. 2 / g, pore volume 0.65cm 3 / g, with an average pore size of 11nm.

[0056] (2) Preparation of methane dry reforming catalyst

[0057] Weigh 9.91g of Ni(NO3)2·6H2O and dissolve it in deionized water to obtain an impregnation solution. Impregnate 20g of the magnesium-aluminum composite oxide support obtained in step (1) in this impregnation solution. After standing for 2 hours, place it in an oven and dry it at 120℃ for 2 hours. Then place the dried sample in a muffle furnace and calcine it at 450℃ for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni / MA2. The content of metallic Ni in Ni / MA2 is 8.9wt%.

[0058] Example 3

[0059] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0060] (1) Preparation of magnesium-aluminum composite oxide carrier

[0061] 128g of Mg(NO3)2·6H2O was weighed and dissolved in 250mL of deionized water to prepare a magnesium nitrate solution; 117g of aluminum hydroxide was weighed and dissolved in 2mol / L nitric acid solution to form an aluminum sol; the magnesium nitrate solution and aluminum sol were mixed and the pH was adjusted to 4 with nitric acid solution, and stirred continuously for 2h to obtain a suspension; the obtained suspension was dried at 100℃ for 2h and calcined at 900℃ in air atmosphere for 4h to obtain a magnesium-aluminum composite oxide carrier, denoted as MA3, whose specific surface area was measured to be 245m² by nitrogen adsorption method. 2 / g, pore volume is 0.78cm 3 / g, with an average pore size of 9nm.

[0062] (2) Preparation of methane dry reforming catalyst

[0063] Weigh 9.91g of Ni(NO3)2·6H2O and dissolve it in deionized water to obtain an impregnation solution. Impregnate 20g of the magnesium-aluminum composite oxide support obtained in step (1) in this impregnation solution. After standing for 2 hours, place it in an oven and dry it at 120℃ for 2 hours. Then place the dried sample in a muffle furnace and calcine it at 450℃ for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni / MA3. The content of metallic Ni in Ni / MA3 is 8.9wt%.

[0064] Example 4

[0065] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0066] 9.91 g of Ni(NO3)2·6H2O and 4.94 g of Co(NO3)2·6H2O were weighed and dissolved in deionized water to obtain an impregnation solution. 20 g of the MA2 support obtained in Example 2 was impregnated in this impregnation solution. After standing for 2 hours, it was placed in an oven and dried at 120°C for 2 hours. The dried sample was then placed in a muffle furnace and calcined at 450°C for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni-Co / MA2. The content of metallic Ni in Ni-Co / MA2 was 8.4 wt%, and the content of metallic Co was 5.3 wt%.

[0067] Example 5

[0068] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0069] 9.91 g of Ni(NO3)2·6H2O and 3.10 g of Ce(NO3)3·6H2O were weighed and dissolved in deionized water to obtain an impregnation solution. 20 g of the MA2 support obtained in Example 2 was impregnated in this impregnation solution. After standing for 2 hours, it was placed in an oven and dried at 120°C for 2 hours. The dried sample was then placed in a muffle furnace and calcined at 450°C for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni-Ce / MA2. The content of metallic Ni in Ni-Ce / MA2 was 8.4 wt%, and the content of metallic Ce was 5.3 wt%.

[0070] Example 6

[0071] This embodiment provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0072] 9.91 g of Ni(NO3)2·6H2O and 7.23 g of Fe(NO3)3·9H2O were weighed and dissolved in deionized water to obtain an impregnation solution. 20 g of the MA2 support obtained in Example 2 was impregnated in this impregnation solution. After standing for 2 hours, it was placed in an oven and dried at 120°C for 2 hours. The dried sample was then placed in a muffle furnace and calcined at 450°C for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni-Fe / MA2. The content of metallic Ni in Ni-Fe / MA2 was 8.4 wt%, and the content of metallic Fe was 5.3 wt%.

[0073] Comparative Example 1

[0074] This comparative example provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0075] (1) Preparation of magnesium-aluminum composite oxide carrier by the mixing method

[0076] 44g of MgO and 43g of aluminum hydroxide powder were weighed and mixed evenly in a kneader to obtain the first mixture. 320mL of 1.2mol / L dilute nitric acid was prepared and mixed with 33g of boehmite to obtain the second mixture. The first and second mixtures were kneaded for another 20 minutes in a kneader, discharged, and dried at 120℃ for 1 hour in a blower dryer. After calcination at 900℃ for 2 hours, a magnesium-aluminum composite oxide carrier, denoted as DMA1, was obtained. Its specific surface area was measured to be 85m² by nitrogen adsorption. 2 / g, pore volume 0.35cm 3 / g, with an average pore size of 18nm.

[0077] (2) Preparation of methane dry reforming catalyst

[0078] Weigh 9.91g of Ni(NO3)2·6H2O and dissolve it in deionized water to obtain an impregnation solution. Impregnate 20g of the magnesium-aluminum composite oxide support obtained in step (1) in this impregnation solution. After standing for 2 hours, place it in an oven and dry it at 120℃ for 2 hours. Then place the dried sample in a muffle furnace and calcine it at 450℃ for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni / DMA1. The content of metallic Ni in Ni / DMA1 is 8.9wt%.

[0079] Comparative Example 2

[0080] This comparative example provides a methane dry reforming catalyst, which is prepared by a method including the following specific steps:

[0081] (1) Preparation of magnesium-aluminum composite oxide carrier

[0082] 282g of Mg(NO3)2·6H2O and 43g of aluminum hydroxide were weighed and mixed evenly in a kneader to obtain a first mixture. 320mL of 1.2mol / L dilute nitric acid was prepared and mixed with 43g of aluminum hydroxide to obtain a second mixture. The first and second mixtures were kneaded for another 20 minutes in a kneader, discharged, dried at 120℃ for 1 hour in a blower dryer, and then calcined at 900℃ for 2 hours to obtain a magnesium-aluminum composite oxide carrier, denoted as DMA2. Its specific surface area was determined to be 88m² by nitrogen adsorption. 2 / g, pore volume is 0.34cm 3 / g, with an average pore size of 16nm.

[0083] (2) Preparation of methane dry reforming catalyst

[0084] Weigh 9.91g of Ni(NO3)2·6H2O and dissolve it in deionized water to obtain an impregnation solution. Impregnate 20g of the magnesium-aluminum composite oxide support obtained in step (1) in this impregnation solution. After standing for 2 hours, place it in an oven and dry it at 120℃ for 2 hours. Then place the dried sample in a muffle furnace and calcine it at 450℃ for 2 hours to obtain a methane dry reforming catalyst, denoted as Ni / DMA2. The content of metallic Ni in Ni / DMA2 is 8.9wt%.

[0085] The performance parameters of the magnesium-aluminum composite oxide carriers used in Examples 1-6 and Comparative Examples 1-2 of this invention are shown in Table 1 below.

[0086] Table 1

[0087]

[0088]

[0089] Application Example 1

[0090] This application example uses the methane dry reforming catalysts provided in Examples 1-6 and Comparative Examples 1-2 of the present invention to catalyze the dry reforming reaction of methane to produce syngas, specifically including:

[0091] 0.2 g of the methane dry reforming catalysts provided in Examples 1-6 and Comparative Examples 1-2 of this invention were weighed out, diluted to 10 mL with 40-60 mesh quartz sand, and then loaded into a quartz tube reactor. Reduction was carried out at 700 °C for 3 hours under an atmosphere of 5 v% hydrogen and 95 v% nitrogen at a pressure of 0.1 MPa. After reduction, the temperature was raised to 800 °C under a nitrogen atmosphere, and then the reaction was carried out using feed gas. The feed gas ratio was CH4 / CO2 molar ratio = 1 / 1, the reaction space velocity was 100000 ml / g / h, and the reaction pressure was 0.1 MPa. After the reaction, the tail gas composition was analyzed by online gas chromatography. The experimental data are shown in Table 2 below. The performance curves of the methane dry reforming catalysts provided in Examples 1 and Comparative Example 1 for catalyzing the methane dry reforming reaction are shown in the figure below. Figure 2 As shown.

[0092] Table 2

[0093] Methane conversion rate / % Carbon dioxide conversion rate / % <![CDATA[H2 / CO molar ratio <!-- 7 -->]]> Ni / MA1 84.4 91.7 0.98 Ni / MA2 83.9 91.3 0.98 Ni / MA3 86.8 92.6 0.99 Ni-Co / MA2 88.6 94.3 0.98 Ni-Ce / MA2 87.4 93.8 0.98 Ni-Fe / MA2 87.7 93.6 0.98 Ni / DMA1 71.9 77.2 0.92 Ni / DMA2 70.6 75.9 0.93

[0094] From Tables 1-2 and above Figure 2 It can be seen that the magnesium-aluminum composite oxide supports prepared by the existing kneading method in Comparative Examples 1 and 2 have a small specific surface area. The methane dry reforming catalysts prepared using these magnesium-aluminum composite oxide supports have low catalytic activity and poor catalyst stability when catalyzing the dry reforming reaction of methane to produce syngas. In contrast, the magnesium-aluminum composite oxide supports prepared in Examples 1-6 of this invention all have a high specific surface area. The methane dry reforming catalysts prepared using these supports have high catalytic activity and stability.

[0095] 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 method for preparing a magnesium-aluminum composite oxide carrier, characterized in that, The preparation method includes: Step (1): Dissolve the magnesium salt in deionized water to form a magnesium salt solution; Step (2): Dissolve the aluminum source in an acid solution to form an aluminum sol; Step (3): Mix the magnesium salt solution and aluminum sol and adjust the pH to 3-4 with an acid solution. After continuous stirring, a suspension is obtained. In the suspension, the molar ratio of aluminum to magnesium is 1:1-3:

1. Step (4): The suspension is dried and calcined to obtain a magnesium-aluminum composite oxide carrier.

2. The preparation method according to claim 1, characterized in that, The magnesium salt includes any one or a combination of magnesium nitrates, sulfates, and chlorides.

3. The preparation method according to claim 1 or 2, characterized in that, The aluminum source includes any one or a combination of two of boehmite and aluminum hydroxide.

4. The preparation method according to claim 1 or 2, characterized in that, The acid solution includes any one of nitric acid, sulfuric acid, and hydrochloric acid, and the concentration of the acid solution is 0.5-6 mol / L.

5. The preparation method according to claim 1 or 2, characterized in that, The drying temperature is 100-120℃, and the time is 2-10h.

6. The preparation method according to claim 1 or 2, characterized in that, The calcination conditions include: air atmosphere, calcination temperature of 700-1100℃, and calcination time of 1-5 hours.

7. A magnesium-aluminum composite oxide carrier, which is prepared by the method of preparing the magnesium-aluminum composite oxide carrier according to any one of claims 1-6.

8. The magnesium-aluminum composite oxide carrier according to claim 7, characterized in that, The specific surface area of ​​the magnesium-aluminum composite oxide carrier is 100-250 m². 2 / g, preferably 150-250m 2 / g, more preferably 200-250m 2 / g, pore volume 0.3-0.8cm 3 / g, with an average pore size of 8-20nm.

9. A methane dry reforming catalyst, comprising a support and an active component supported on the support, characterized in that, The carrier is the magnesium-aluminum composite oxide carrier according to claim 7 or 8, and the active component is nickel; The total weight of the methane dry reforming catalyst is 100%, the nickel content is 3-20%, and the balance is the support.

10. The methane dry reforming catalyst according to claim 9, characterized in that, The methane dry reforming catalyst further comprises an additive supported on the support, the additive including one or a combination of sodium, potassium, calcium, strontium, cerium, cobalt, iron, and zirconium; The content of the additive, calculated by metal element, is 0.5-20%, wherein the content of the additive is calculated based on the total weight of the methane dry reforming catalyst as 100%.

11. The method for preparing the methane dry reforming catalyst according to claim 9 or 10, characterized in that, The preparation method includes: The active component's metal salt is prepared into an impregnation solution using deionized water. The magnesium-aluminum composite oxide support described in claim 7 or 8 is then impregnated with the impregnation solution, dried, and calcined to obtain the methane dry reforming catalyst.

12. The preparation method according to claim 11, characterized in that, The drying temperature is 100-120℃, and the drying time is 2-10 hours; And / or the calcination conditions include: air atmosphere, calcination temperature of 400-600℃, and calcination time of 1-5h.

13. The application of the methane dry reforming catalyst according to claim 9 or 10 in the catalytic dry reforming reaction of methane to produce syngas, characterized in that, The applications include: Methane and CO2 are reacted in a fixed-bed reactor in the presence of the methane dry reforming catalyst to produce syngas. The reaction conditions include: a molar ratio of carbon dioxide to methane of 1-1.2:1, a temperature of 600-950℃, a pressure of 0-3MPa, and a feed gas space velocity of 2000-120000mL / g / h.

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