Methanation catalysts, methods of making and using the same, and methanation reaction methods

Abstract

The present application relates to the field of methanation catalyst, disclose a kind of methanation catalyst and its preparation method and application, methanation reaction method, the catalyst includes carrier, active metal component, first modified auxiliary agent and second modified auxiliary agent;Wherein, the carrier is SiO2;The active metal component is nickel;The first modified auxiliary agent is group ⅢB and / or group ⅣB metal;The second modified auxiliary agent is rare earth metal;The average particle size of the active metal component is 8-20nm;Wherein, with the total amount of carrier as benchmark, the sodium content in the carrier is not higher than 0.1wt%, and the sulfur content is not higher than 100ppm.The methanation catalyst provided by the present application has the characteristics of low sodium and low sulfur, greatly improves the catalytic activity of the catalyst in the ultra-low temperature methanation reaction, can realize the efficient purification of crude hydrogen at ultra-low temperature, reduce the concentration of CO to below 10ppm, and the hydrogen quality can meet the requirements of downstream hydrogenation catalyst.

Description

Technical Field

[0001] This invention relates to the field of methanation catalysts, specifically to a methanation catalyst, its preparation method and application, and a methanation reaction method. Background Technology

[0002] Hydrogen as fuel comes from diverse sources. In industrial plants that produce ethylene from naphtha and light hydrocarbons through cracking, the hydrogen-rich gas separated from the hydrogen / methane separator inevitably contains CO and CO2. This portion of hydrogen is the feedstock for downstream hydrogenation processes. If the CO is not removed, it will cause poisoning and deactivation of the hydrogenation catalyst. For example, in ammonia synthesis plants, the feedstock gas after CO conversion and CO2 removal still contains small amounts of CO and CO2. When this feedstock enters the subsequent ammonia synthesis reactor, the total CO and CO2 content must be below 10 ppm. Furthermore, the development and utilization of hydrogen energy, represented by fuel cell technology, is considered one of the most promising clean energy sources of the 21st century. In particular, proton exchange membrane fuel cells, due to their advantages such as low pollution, high efficiency, fast start-up, high power density, and low operating temperature, are considered one of the most competitive power sources to replace gasoline internal combustion engine power, and have become a research hotspot for major research institutions. In proton exchange membrane fuel cells, the Pt electrode's tolerance to CO is less than 10 ppm. Currently, in hydrogen production methods that can be applied on a large scale, such as methane steam reforming and methanol steam reforming, some CO and CO2 will inevitably remain, which will lead to Pt adsorption poisoning and decreased activity.

[0003] To address the above issues, most current H2 purification systems utilize methanation, which removes CO and CO2 from the gas by reacting CO, CO2, and a small amount of hydrogen to generate inert CH4. The hydrogen-rich gas, after recovering its cooling capacity, reaches a temperature of approximately 35°C. After being heated by the tail gas from the methanation reactor, the feed gas needs to be heated using high-pressure steam to reach the temperature required for further methanation. Currently, industrial systems typically use medium-temperature methanation catalysts with a reaction temperature of 280-350°C, while low-temperature methanation catalysts operate at 150-200°C (referred to as ultra-low temperature methanation). Compared to medium-temperature methanation catalysts, using ultra-low temperature methanation catalysts significantly reduces the amount of high-pressure steam used, provides a greater safety margin, and lowers equipment requirements. However, this also places higher demands on catalyst performance; conventional methanation catalysts cannot effectively remove CO from the gas during ultra-low temperature methanation reactions.

[0004] Therefore, the development of methanation catalysts for use under ultra-low temperature conditions is of great significance and has broad prospects. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high reduction temperature and low catalytic activity of catalysts in low-temperature methanation, which make it difficult for crude hydrogen purification products to meet the hydrogen quality requirements of downstream hydrogenation catalysts. This invention provides a methanation catalyst, its preparation method and application, and a methanation reaction method. This methanation catalyst has high catalytic activity and can achieve efficient purification of crude hydrogen under ultra-low temperature conditions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a methanation catalyst, the catalyst comprising a support, an active metal component, a first modifying agent, and a second modifying agent; wherein the support is SiO2; the active metal component is nickel; the first modifying agent is a Group IIIB and / or Group IVB metal; the second modifying agent is a rare earth metal; and the average particle size of the active metal component is 8-20 nm.

[0007] Based on the total amount of carrier, the sodium content in the carrier is no higher than 0.1 wt%, and the sulfur content is no higher than 100 ppm.

[0008] A second aspect of this invention provides a method for preparing a methanation catalyst, comprising the following steps:

[0009] (1) The SiO2 support precursor was subjected to hydrothermal treatment and calcined to obtain the support;

[0010] Based on the total amount of carrier, the sodium content in the carrier is no more than 0.1 wt%, and the sulfur content is no more than 100 ppm;

[0011] (2) The carrier is modified by using a first modifying agent to obtain a modified carrier; wherein the first modifying agent is a group IIIB and / or group IVB metal;

[0012] (3) In the presence of a surfactant, the impregnation solution is contacted with the modified support, and then dried and calcined to obtain the methanation catalyst;

[0013] The impregnation solution contains a soluble compound of an active metal component and a soluble compound of a second modifying agent.

[0014] The active metal component is nickel, and the second modifying agent is a rare earth metal.

[0015] A third aspect of the present invention provides a methanation catalyst prepared by the above-described preparation method.

[0016] The fourth aspect of this invention provides the application of the above-mentioned methanation catalyst in the methanation reaction for crude hydrogen purification.

[0017] The fifth aspect of the present invention provides a methanation reaction method, wherein, under methanation reaction conditions, a feed gas is contacted with a catalyst, wherein the catalyst is the methanation catalyst described in the first and third aspects.

[0018] The methanation catalyst provided by this invention and the methanation catalyst prepared by the method provided by this invention are characterized by low sodium and low sulfur content, which greatly improves the catalytic activity of the catalyst in ultra-low temperature methanation reactions. It can achieve efficient purification of crude hydrogen at ultra-low temperatures, reducing the CO concentration to below 10 ppm, and the hydrogen quality meets the requirements of downstream hydrogenation catalysts. Due to the special modification treatment of the support surface, the interaction strength between the active metal component and the support is significantly weaker than that of catalysts prepared with ordinary Al2O3 supports. In addition, the introduction of surfactants during catalyst preparation reduces the average particle size of the active metal under the synergistic effect of surfactants and promoters. Therefore, this catalyst is particularly easy to reduce and activate, and can be fully reduced and activated at reduction temperatures below 300℃ to obtain high catalytic activity, greatly simplifying the start-up process and thus significantly shortening the start-up time. Attached Figure Description

[0019] Figure 1 These are the XRD patterns of the catalysts obtained in Example 1 and Comparative Example 1;

[0020] Figure 2 These are the H2-TPR spectra of the catalysts obtained in Example 1 and Comparative Example 4. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The first aspect of this invention provides a methanation catalyst, the catalyst comprising a support, an active metal component, a first modifying agent, and a second modifying agent; wherein the support is SiO2; the active metal component is nickel; the first modifying agent is a Group IIIB and / or IVB metal; the second modifying agent is a rare earth metal; and the average particle size of the active metal component is 8-20 nm.

[0023] Based on the total amount of carrier, the sodium content in the carrier is no higher than 0.1 wt%, and the sulfur content is no higher than 100 ppm.

[0024] Compared with existing methanation catalysts, the methanation catalyst provided by this invention features low sodium and low sulfur content. The inventors have creatively discovered that the sodium and sulfur content in the catalyst support has a significant impact on the catalytic activity of the catalyst. By controlling the extremely low sodium and sulfur content in the support, the catalytic activity of the catalyst in ultra-low temperature methanation reactions is greatly improved, enabling efficient purification of crude hydrogen at ultra-low temperatures, and ensuring that the hydrogen quality meets the requirements of downstream hydrogenation catalysts. Furthermore, this catalyst is particularly easy to reduce and activate, achieving sufficient reduction and activation at reduction temperatures below 300°C to obtain high catalytic activity, greatly simplifying the start-up process and thus significantly shortening the start-up time.

[0025] In this invention, preferably, based on the total amount of the support, the sodium content in the support is no higher than 0.05 wt%, and the sulfur content is no higher than 50 ppm. Under these preferred conditions, the catalytic activity of the catalyst can be further improved.

[0026] In this invention, the sodium and sulfur contents are determined by ICP method.

[0027] In this invention, preferably, the support is SiO2 spherical particles. The inventors discovered in their research that, under the above-mentioned preferred conditions, the interaction strength between the active metal component and the support is significantly weaker than that of catalysts prepared with ordinary Al2O3 supports, thus making the catalyst easier to reduce and activate.

[0028] According to the present invention, compared with catalysts prepared by prior art, the active metal component of the catalyst provided by the present invention can achieve a higher degree of reduction at a lower reduction temperature, and the average grain size of the active metal component is small. Preferably, after the catalyst is reduced at 300°C for 3 hours, the degree of reduction of the active metal component is 75-97%, more preferably 80-95%. In contrast, in the prior art, under the same reduction conditions, the degree of reduction of nickel is generally below 50%.

[0029] The specific reduction conditions described in this invention include: weighing 1g of catalyst, loading it into a fixed-bed reactor, and activating it by reduction at 300°C for 3 hours under normal pressure and a pure hydrogen atmosphere.

[0030] In this invention, the degree of reduction of the active metal component refers to the molar percentage of the active metal component in its elemental state relative to the total amount of active metal components. The degree of reduction of the active metal component can be characterized using a temperature-programmed reduction method.

[0031] In this invention, the average particle size of the active metal component can be obtained by XRD and calculated according to the Scherrer formula. In existing industrial catalysts, the average particle size of nickel in nickel-based methanation catalysts is 20-35 nm. In this invention, preferably, the average particle size of the active metal component is 10-18 nm.

[0032] In this invention, preferably, the particle size of the carrier is 1-6 mm, and more preferably 3-5 mm.

[0033] In this invention, preferably, the specific surface area of ​​the carrier is 250-480 m². 2 / g, further preferably 300-450m 2 / g.

[0034] In this invention, preferably, the catalyst has a specific surface area of ​​150-380 m². 2 / g, further preferably 180-350m 2 / g, more preferably 220-350m 2 / g. Under the above-mentioned preferred conditions, it is beneficial to further improve the catalytic activity of the catalyst.

[0035] According to the present invention, the first modifying agent is used for carrier modification. Preferably, the first modifying agent is selected from at least one of Sc, Zr, Hf, Ti, and Y, and more preferably at least one of Y, Ti, and Zr. Using the above-mentioned preferred first modifying agent is beneficial for promoting the dispersion of active metals and improving the activity of the catalyst.

[0036] In this invention, preferably, the second modifying agent is selected from at least one of La, Ce, Pr and Sm, and more preferably La and / or Ce; the combined effect of the active metal component and the second modifying agent is beneficial to improving the thermal stability of the catalyst.

[0037] In this invention, preferably, based on the total amount of the catalyst, the content of the support is 35-89.8 wt%, more preferably 48-76 wt%; the content of the active metal component, calculated as oxides, is 10-45 wt%, more preferably 20-40 wt%; the content of the first modifying agent is 0.1-10 wt%, more preferably 2-6 wt%; and the content of the second modifying agent is 0.1-10 wt%, more preferably 2-6 wt%. It should be noted that since the active metal component may actually exist in oxide form or in elemental form, and the above-mentioned active metal component is calculated based on oxide content, the content of the active metal component is larger than the actual content. It is understood that when the catalyst contains only the above-mentioned active metal component, the first modifying agent, the second modifying agent, and the support, the total amount of the active metal component, the first modifying agent, the second modifying agent, and the support must necessarily satisfy 100%.

[0038] In this invention, the contents of the active metal component, the first modifying agent, and the second modifying agent are determined by ICP method.

[0039] Preferably, the mass ratio of the second modifying agent to the active metal component, calculated as oxide, is 0.05-0.25:1, more preferably 0.07-0.2:1. Under these preferred conditions, the synergistic effect of the active metal component and the second modifying agent is further improved, which helps to enhance the thermal stability of the catalyst while maximizing its activity.

[0040] A second aspect of this invention provides a method for preparing a methanation catalyst, comprising the following steps:

[0041] (1) The SiO2 support precursor was subjected to hydrothermal treatment and calcined to obtain the support;

[0042] Based on the carrier mass, the sodium content in the carrier is no higher than 0.1 wt%, and the sulfur content is no higher than 100 ppm.

[0043] (2) The carrier is modified by using a first modifying agent to obtain a modified carrier; wherein the first modifying agent is a group IIIB and / or group IVB metal;

[0044] (3) In the presence of a surfactant, the impregnation solution is contacted with the modified support, and then dried and calcined to obtain the methanation catalyst;

[0045] The impregnation solution contains a soluble compound of an active metal component and a soluble compound of a second modifying agent.

[0046] The active metal component is nickel, and the second modifying agent is a rare earth metal.

[0047] According to the present invention, the precursor is first desulfurized and desodiumed through hydrothermal treatment, followed by support modification, and finally loading of active metal components. By controlling the extremely low sodium and sulfur content in the support, the catalytic activity of the catalyst in the ultra-low temperature methanation reaction is greatly improved, enabling efficient purification of crude hydrogen at ultra-low temperatures. Simultaneously, the combination of the above steps helps improve the dispersibility of the active metal and reduces the interaction between the active metal and the support, thereby improving the activity and stability of the catalyst.

[0048] In this invention, the SiO2 support precursor can be a commercially available or conventionally prepared SiO2 support. It is understood that the SiO2 support precursor is a conventional support with a high sodium and sulfur content. Generally, conventional SiO2 supports contain 0.5-1% sodium and 0.2-0.4% sulfur. The shape of the SiO2 support precursor can be selected according to the needs of different types of reactors used in actual production. When the catalyst is applied to a fixed-bed reactor, the SiO2 support precursor is preferably SiO2 spherical particles.

[0049] In this invention, preferably, the preparation method further includes sieving the SiO2 carrier precursor before hydrothermal treatment to remove surface dust.

[0050] In this invention, preferably, the hydrothermal treatment includes: mixing the SiO2 support precursor with water, and then performing hydrothermal treatment. Preferably, the volume ratio of water to the SiO2 support precursor is 1-3:1, more preferably 1.5-2.5:1.

[0051] According to the present invention, the above-mentioned hydrothermal treatment can be carried out in a conventional hydrothermal device, preferably, the filling amount of the hydrothermal device does not exceed one-third of the volume of the hydrothermal device.

[0052] In this invention, preferably, the hydrothermal treatment conditions are: a reaction temperature of 60-120℃, more preferably 70-90℃; and a time of 1-10 hours, more preferably 2-5 hours. Preferably, the hydrothermal treatment is carried out in a sealed state. Using the above-mentioned preferred embodiments facilitates the rapid dissolution of sodium from the carrier.

[0053] Preferably, the method further includes, after hydrothermal treatment, naturally cooling the product to room temperature, and then washing and drying to obtain the carrier. The washing and drying can be conventional operations in the art. Preferably, the washing solution is deionized water; the drying temperature is preferably 100-150℃, and the drying time is preferably 1-3 hours.

[0054] In this invention, preferably, in step (1), the calcination conditions are: a calcination temperature of 400-800℃, more preferably 450-600℃, for example, typical but not limiting temperatures such as 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, and 600℃. Preferably, the calcination time is 1-5 hours, more preferably 1.5-3.5 hours. Under the above preferred conditions, it is beneficial to improve the desulfurization effect. If the calcination temperature is too low, the desulfurization effect is poor; if the calcination temperature is too high, it may lead to a decrease in the specific surface area and water absorption rate of the support, affecting the activity of the catalyst.

[0055] According to the present invention, preferably, based on the total amount of the support, the sodium content in the support is not higher than 0.05 wt%, and the sulfur content is not higher than 50 ppm. Under these preferred conditions, the catalytic activity of the catalyst can be further improved.

[0056] In this invention, the specific operation of the modification treatment can be carried out in a manner well known to those skilled in the art. Preferably, in step (2), the modification treatment includes: impregnating or spraying the carrier with a solution of a soluble compound containing a first modifying agent, and then drying and calcining to obtain a modified carrier. Preferably, the solution of a soluble compound containing a first modifying agent is sprayed onto the carrier. Using the above preferred embodiment is beneficial to improving the uniformity of impregnation.

[0057] In this invention, there is no particular limitation on the concentration of the solution containing the soluble compound of the first modifying agent, which can be adjusted according to actual needs.

[0058] In this invention, the drying and calcination in step (2) can be conventional operations in the art.

[0059] Preferably, the drying temperature can be 80-150℃, more preferably 100-130℃, and the drying time is 1-10h, more preferably 2-6h.

[0060] Preferably, the roasting temperature in step (2) can be 400-700℃, more preferably 450-600℃, and the roasting time is 1-5h, more preferably 2-4h.

[0061] Preferably, the first modifying agent is selected from at least one of Sc, Zr, Hf, Ti, and Y, more preferably at least one of Y, Ti, and Zr, and most preferably Zr. Using the above-mentioned preferred first modifying agent is beneficial for promoting the dispersion of active metals and improving the activity of the catalyst.

[0062] According to the present invention, in step (3), there are no particular limitations on the conditions under which the impregnation solution contacts the modified carrier. For example, the conditions under which the impregnation solution contacts the modified carrier include: a temperature of 10-50°C, preferably 15-30°C; and a time of 0.5-10 hours, preferably 2-5 hours.

[0063] The present invention does not particularly limit the contact method between the impregnation solution and the modified carrier. For example, the impregnation solution containing the surfactant, a soluble compound containing an active metal component, and a soluble compound containing a second modifying agent can be mixed first, and then impregnated or sprayed onto the modified carrier. The specific operating conditions for impregnation or spraying can be adjusted according to actual needs, and can be the same as or different from the operation in step (2) above, which will not be repeated here.

[0064] In this invention, the type of surfactant can be a conventional choice in the art. Preferably, the surfactant is selected from at least one of anionic surfactants, amphoteric surfactants, and nonionic surfactants; more preferably, it is at least one of stearic acid, oleic acid, lauric acid, lecithin, dodecylaminopropionic acid, alkyl dimethyl betaine, fatty acid glycerides, polyols, Tween 60, and P123; more preferably, it is at least one of P123, oleic acid, and Tween 60.

[0065] In this invention, the amount of surfactant used is not particularly limited. However, in order to form a catalyst with higher activity and better stability, preferably, the molar ratio of the surfactant to the total amount of the soluble compound of the active metal component (calculated as metal element) and the soluble compound of the second modifying agent is 6 × 10⁻⁶. -6 -3×10 -5 :1, preferably 1×10 -5 -2×10 -5 :1.

[0066] In this invention, preferably, the second modifying agent is selected from at least one of La, Ce, Pr and Sm, and more preferably La and / or Ce.

[0067] Preferably, in the impregnation solution, the total concentration of the soluble compounds of the active metal component and the soluble compounds of the second modifying agent, calculated by metal element, is 0.6-1 kg / L.

[0068] Preferably, the amounts of the soluble compound of the active metal component and the soluble compound of the second modifying agent are such that, in the prepared catalyst, the mass ratio of the second modifying agent to the active metal component, based on oxides, is 0.05-0.25:1, more preferably 0.07-0.2:1. Using the preferred embodiment of the present invention is beneficial for improving the thermal stability of the catalyst while ensuring maximum catalyst activity.

[0069] In this invention, there is no particular limitation on the selection of the soluble compound of the active metal component. For example, the soluble compound of the active metal component is selected from nickel nitrate and / or nickel acetate; nickel nitrate is more preferably selected.

[0070] According to the present invention, the types of soluble compounds of the first and second modifying agents are well known to those skilled in the art and can be conventional choices in the art. For example, the soluble compounds of the first and second modifying agents are each independently selected from at least one of their respective nitrates, chlorides, and acetates; more preferably, nitrates.

[0071] In this invention, the soluble compounds of the active metal component and the soluble compounds of the second modifying agent may contain water of crystallization, which is well known to those skilled in the art and will not be described in detail here.

[0072] This invention offers a wide range of options for the amounts of the support, active metal component, first modifying agent, and soluble compound of the second modifying agent. Preferably, the amounts of the support, active metal component, first modifying agent, and second modifying agent are such that, based on the total amount of catalyst, the content of the support is 35-89.8 wt%, preferably 48-76 wt%; the content of the active metal component (calculated as oxide) is 10-45 wt%, preferably 20-40 wt%; the content of the first modifying agent is 0.1-10 wt%, preferably 2-6 wt%; and the content of the second modifying agent is 0.1-10 wt%, preferably 2-6 wt%.

[0073] In this invention, the product after contact between the impregnation liquid and the carrier is dried and calcined, wherein the drying and calcining conditions are well known to those skilled in the art. Preferably, the drying temperature is 80-140℃, more preferably 100-120℃, and the drying time is 1-10h, more preferably 2-6h.

[0074] Preferably, the roasting temperature can be 300-600℃, more preferably 350-500℃, and the time can be 1-10h, more preferably 2-6h.

[0075] The third aspect of the present invention also provides a methanation catalyst prepared by the above preparation method.

[0076] The fourth aspect of the present invention also provides the application of the above-mentioned methanation catalyst in the methanation reaction for crude hydrogen purification.

[0077] According to the present invention, the methanation catalyst is applicable to a wide range of reaction temperatures, and is particularly preferred for use in ultra-low temperature crude hydrogen purification methanation reactions.

[0078] The fifth aspect of the present invention also provides a methanation reaction method, wherein, under methanation reaction conditions, a feed gas is contacted with a catalyst, wherein the catalyst is the methanation catalyst described above.

[0079] According to the present invention, preferably, the raw material gas is crude hydrogen gas containing CO, and more preferably, the volume concentration of H2 in the crude hydrogen gas is 99-99.8%, and the volume concentration of CO is 2000-10000 ppm, preferably 3000-8000 ppm.

[0080] When the catalyst provided by the present invention is used in a methanation reaction, the contact can be carried out in a fixed-bed reactor or a fluidized-bed reactor, preferably in a fixed-bed reactor.

[0081] Preferably, the conditions for the methanation reaction include: a reaction temperature of 150-350℃, more preferably 150-250℃; a reaction pressure of 0-6 MPa, more preferably 2-4 MPa; and a feed gas volume hourly space velocity of 1000-12000 h⁻¹. -1 Preferably 6000-10000h -1 .

[0082] When the catalyst provided by the present invention is used in a dry reforming reaction of methane, the method further includes reducing and activating the catalyst in the presence of hydrogen before the methanation reaction.

[0083] Preferably, the reduction activation conditions include: a reduction temperature of 200-600℃, more preferably 260-350℃, and a reduction time of 0.5-10 h, more preferably 1-5 h; the reduction can be carried out in pure hydrogen or in a mixture of hydrogen and an inert gas, such as a mixture of hydrogen and nitrogen and / or argon, with a hydrogen pressure of 0-2 MPa, more preferably 0-1 MPa, more preferably 0-0.5 MPa, and a hydrogen volume hourly space velocity of 300-3000 h⁻¹. -1 Preferably 500-2000h -1 .

[0084] The present invention will be described in detail below through embodiments.

[0085] In the following examples, the SiO2 spheres used are commercially available products with a diameter of 3-5 mm, a sodium ion content of 0.8 wt%, a sulfur content of 0.2 wt%, and a specific surface area of ​​332 m². 2 / g, water absorption rate is 0.89%.

[0086] The Al2O3 spheres used are commercially available, with a diameter of 3-5 mm, a sodium ion content of 0.3 wt%, a sulfur content of 0.04 wt%, and a specific surface area of ​​269 m².2 / g, water absorption rate is 0.68%.

[0087] The composition of exhaust gas was calculated by online sampling and analysis using gas chromatography.

[0088] The contents of Na, S, active metal components, the first modifying agent, and the second modifying agent were determined by ICP method.

[0089] The average particle size of the active metal component can be obtained by XRD and calculated according to the Scherrer formula.

[0090] Example 1

[0091] (1) Preparation of catalyst

[0092] Weigh 1.0m 3 SiO2 balls were poured into a hydrothermal reactor, and 2m... 3 Deionized water was heated to 80°C and subjected to a sealed hydrothermal treatment for 3 hours. The mixture was then opened and allowed to cool naturally to room temperature. It was then washed three times with deionized water and dried at 120°C for 2 hours. The dried support was calcined at 550°C for 2.5 hours to obtain a low-sodium, low-sulfur SiO2 support with a sodium content of 0.03 wt% and a sulfur content of 45 ppm.

[0093] The surface of the SiO2 spherical support was then modified, with ZrO2 as the first modifying agent. First, 100 kg of the SiO2 support was weighed, and based on the final total catalyst mass, the amount of ZrO2 added was 4 wt%. 22.8 kg of Zr(NO3)4·5H2O was weighed and dissolved in deionized water, and the volume was adjusted to 85 L. After complete dissolution, the solution was sprayed onto the support, mixed by rotation for 30 minutes, and then dried in a mesh belt dryer at 120°C for 3 hours, followed by calcination at 500°C for 3 hours to obtain the desired modified support.

[0094] A catalyst was prepared using the modified support described above. 65 kg of the modified support was weighed, and 116.8 kg of Ni(NO3)2·6H2O and 13.3 kg of La(NO3)3·9H2O were weighed according to the final catalyst content of 30 wt% NiO and 5 wt% La2O3, respectively, and dissolved in deionized water. Separately, 35 g of P123 was weighed and added to the above solution, and the volume was adjusted to 45.5 L. This solution was then sprayed onto the modified support. The molar ratio of the surfactant to the total molar amount of Ni and La was approximately 1.4 × 10⁻⁶. -5 1. After rotary mixing for 30 minutes, the mixture is dried in a mesh belt dryer at 120°C for 3 hours, and then calcined at 400°C for 2 hours to obtain the desired ultra-low temperature methanation catalyst. Figure 1The XRD pattern of the catalyst shows that the average particle size of Ni particles in the obtained catalyst is relatively small, with the average particle size of metallic Ni particles being only 11.4 nm. The composition and specific surface area data of the catalyst are shown in Table 1.

[0095] The H2-TPR spectrum of the catalyst obtained in Example 1 is shown in Figure 1. Figure 2 As can be seen from the figure, the reduction temperature of the catalyst is significantly reduced. There are two reduction peaks on the reduction spectrum. The first reduction peak is located at 320℃ and the second reduction peak is located at 470℃. Moreover, the peak area of ​​the second reduction peak is relatively small, indicating that the catalyst can be easily reduced and activated.

[0096] (2) Activity evaluation

[0097] 1 g of the catalyst obtained in Example 1 was weighed and packed into a fixed-bed reactor. Activation was performed by reduction at 300°C for 3 hours under normal pressure in a pure hydrogen atmosphere, with a hydrogen volume hourly space velocity of 1000 h⁻¹. -1 The reduction degree of metallic Ni was 89%, and the average particle size of metallic Ni was 11.4 nm.

[0098] After reduction, the temperature was lowered to 150°C in a hydrogen atmosphere, and the feed gases (H2 volume concentration of 99.5% and CO volume concentration of 5000 ppm) were switched to continue the reaction at a space velocity of 10000 h⁻¹. -1 The reaction pressure was 2 MPa. Online gas chromatography analysis of the tail gas composition revealed no detectable CO concentration.

[0099] Example 2

[0100] (1) Preparation of catalyst

[0101] Following the method of Example 1, except that the first modifying agent was Y2O3, a methanation catalyst was obtained. The composition and specific surface area data of the catalyst are shown in Table 1.

[0102] (2) Activity evaluation

[0103] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 85% for metallic Ni and an average particle size of 14.8 nm for metallic Ni.

[0104] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas showed a CO concentration of 2 ppm.

[0105] Example 3

[0106] (1) Preparation of catalyst

[0107] Following the method of Example 1, except that the ZrO2 loading was 2 wt% based on the final total catalyst mass, a methanation catalyst was obtained. The composition and specific surface area data of the catalyst are shown in Table 1.

[0108] (2) Activity evaluation

[0109] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 92% for metallic Ni and an average particle size of 10.6 nm for metallic Ni.

[0110] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The composition of the tail gas was analyzed by online gas chromatography, and CO concentration was not detected in the tail gas.

[0111] Example 4

[0112] (1) Preparation of catalyst

[0113] Weigh 1.0m 3 SiO2 balls were poured into a hydrothermal reactor, and 2m... 3 Deionized water was heated to 90°C and subjected to a sealed hydrothermal treatment for 2 hours. The mixture was then opened and allowed to cool naturally to room temperature. It was then washed three times with deionized water and dried at 120°C for 2 hours. The dried support was calcined at 600°C for 2 hours to obtain a low-sodium, low-sulfur SiO2 support with a sodium content of 0.02 wt% and a sulfur content of 32 ppm.

[0114] The support was modified and the active metal was loaded in the same manner as in Example 1 to obtain the desired methanation catalyst. The composition and specific surface area data of the catalyst are shown in Table 1.

[0115] (2) Activity evaluation

[0116] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 82% for metallic Ni and an average particle size of 15.6 nm for metallic Ni.

[0117] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The CO concentration in the tail gas was 5 ppm as determined by online gas chromatography.

[0118] Example 5

[0119] (1) Preparation of catalyst

[0120] The support modification and catalyst preparation were carried out using the same method as in Example 1, except that CeO2 was used as the second modifying agent to obtain the methanation catalyst. The composition and specific surface area data of the catalyst are shown in Table 1.

[0121] (2) Activity evaluation

[0122] Reduction activation was performed under the same conditions as in Example 1, and the reduction degree of metallic Ni was 87.9%, with an average particle size of 11.8 nm.

[0123] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The CO concentration in the tail gas was 1 ppm as determined by online gas chromatography.

[0124] Example 6

[0125] (1) Preparation of catalyst

[0126] The support modification and catalyst preparation were carried out using the same method as in Example 1, except that oleic acid was used to replace P123, with the same ratio of surfactant molar to total molar Ni and La, to obtain the methanation catalyst. The composition and specific surface area data of the catalyst are shown in Table 1.

[0127] (2) Activity evaluation

[0128] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 84% for metallic Ni and an average particle size of 14.6 nm for metallic Ni.

[0129] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The CO concentration in the tail gas was 6 ppm as determined by online gas chromatography.

[0130] Example 7

[0131] (1) Preparation of catalyst

[0132] The support modification and catalyst preparation were carried out using the same method as in Example 1, except that the content of the active metal NiO was 40 wt%, resulting in a methanation catalyst. The composition and specific surface area data of the catalyst are shown in Table 1.

[0133] (2) Activity evaluation

[0134] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 86% for metallic Ni and an average particle size of 16 nm for metallic Ni.

[0135] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The CO concentration in the tail gas was analyzed by online gas chromatography and no CO was detected.

[0136] Example 8

[0137] The catalyst was prepared using the same method as in Example 1, except that the calcination temperature of the sample after hydrothermal treatment was 500°C. The resulting SiO2 support contained 0.04% sodium and 53 ppm sulfur, and then a methanation catalyst was prepared using the same method as in Example 1. The composition and specific surface area data of the catalyst are shown in Table 1.

[0138] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 89% for metallic Ni and an average particle size of 10.3 nm for metallic Ni.

[0139] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. The CO concentration in the tail gas was 2 ppm as determined by online gas chromatography.

[0140] Comparative Example 1

[0141] (1) Preparation of catalyst

[0142] The catalyst was prepared using the same method as in Example 1, except that no surfactant was added during the impregnation of the active metal. The resulting catalyst was designated DB-1. The composition and specific surface area data of the catalyst are shown in Table 1.

[0143] (2) Activity evaluation

[0144] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 81.6% for metallic Ni and an average particle size of 27.3 nm for metallic Ni.

[0145] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas CO concentration showed a value of 265 ppm. Figure 1 The XRD pattern of the catalyst shows that this is mainly because the active metal has a larger grain size when no surfactant is added, resulting in poor catalyst activity.

[0146] Comparative Example 2

[0147] (1) Preparation of catalyst

[0148] The method described in Example 1 was followed, except that the commercially available SiO2 spheres were not subjected to hydrothermal treatment, but were directly calcined at 550°C for 2.5 hours. The resulting SiO2 support contained 0.8 wt% sodium and 39 ppm sulfur. A catalyst was then prepared using the same method as in Example 1, and the resulting catalyst was designated DB-2. The composition and specific surface area data of the catalyst are shown in Table 1.

[0149] (2) Activity evaluation

[0150] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 81.4% for metallic Ni and an average particle size of 19.5 nm for metallic Ni.

[0151] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas showed a CO concentration of 361 ppm. This indicates that the high sodium content in the support has a significant impact on catalyst activity.

[0152] Comparative Example 3

[0153] (1) Preparation of catalyst

[0154] Following the method of Example 1, except that commercially available SiO2 balls were hydrothermally treated and then calcined at 300°C for 2 hours, resulting in a SiO2 support with a sodium content of 0.04 wt% and a sulfur content of 363 ppm. A catalyst was then prepared using the same method as in Example 1, and the resulting catalyst was designated DB-3. The composition and specific surface area data of the catalyst are shown in Table 1.

[0155] (2) Activity evaluation

[0156] Reduction activation was performed under the same conditions as in Example 1, and the reduction degree of metallic Ni was 88.9%, with an average particle size of 12.5 nm.

[0157] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas CO concentration showed a value of 247 ppm. This indicates that excessive residual sulfur content in the support significantly affects catalyst activity.

[0158] Comparative Example 4

[0159] (1) Preparation of catalyst

[0160] Using commercially available Al2O3 spheres as a carrier, the first auxiliary component, the active metal component, and the second auxiliary component were directly loaded according to the method of Example 1. The resulting catalyst is designated DB-4, and its H2-TPR spectrum is shown in [Figure / Image]. Figure 2 The composition and specific surface area data of the catalyst are shown in Table 1.

[0161] (2) Activity evaluation

[0162] Reduction activation was performed under the same conditions as in Example 1, and the H2-TPR spectrum of the resulting catalyst is shown in [Figure / Diagram]. Figure 2 In the study, the reduction degree of metallic Ni was 39.4%, and the average particle size of metallic Ni was 16.3 nm.

[0163] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis showed that the CO concentration in the tail gas was 1320 ppm. This is mainly because the interaction between NiO and the Al2O3 support is strong, making reduction and activation difficult, and the active metal cannot function effectively.

[0164] Comparative Example 5

[0165] (1) Preparation of catalyst

[0166] Following the method in Example 1, except that the obtained low-sodium, low-sulfur SiO2 support was directly impregnated with an active metal and a second modifying agent, and the resulting catalyst was designated DB-5. The composition and specific surface area data of the catalyst are shown in Table 1.

[0167] (2) Activity evaluation

[0168] Reduction activation was performed under the same conditions as in Example 1, with a reduction degree of 76.3% for metallic Ni and an average particle size of 26.6 nm for metallic Ni.

[0169] The catalyst was activated and methanation was carried out under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas showed a CO concentration of 75 ppm. This indicates that surface modification of the support can significantly improve the catalyst activity.

[0170] Table 1

[0171]

[0172]

[0173] As can be seen from the above examples and comparative examples, the methanation catalyst obtained by the preparation method of the present invention has the characteristics of low sodium and low sulfur, which greatly improves the catalytic activity of the catalyst in the ultra-low temperature methanation reaction. It can achieve efficient purification of crude hydrogen at ultra-low temperatures, reducing the CO concentration to below 10 ppm, and the hydrogen quality can meet the requirements of downstream hydrogenation catalysts. According to Example 1 and Comparative Examples 2-3, it can be seen that when the sodium and sulfur content in the catalyst is too high, the catalytic activity of the catalyst is limited, and CO in the crude hydrogen gas cannot be fully removed, making it difficult to meet the requirements of downstream hydrogenation catalysts. According to Example 1 and Comparative Example 4, and... Figure 2It can be seen that, due to the special modification treatment of the support surface, the interaction strength between the active metal component and the support is significantly weaker than that of the catalyst prepared with ordinary Al2O3 support. Therefore, it can be fully reduced and activated at a reduction temperature below 300℃, resulting in higher catalytic activity. Examples 1, 4, and 5 show that appropriate hydrothermal treatment and calcination of the SiO2 support precursor can significantly reduce the Na and S content in the support and improve catalyst activity. However, when the calcination temperature is too high, the specific surface area and water absorption rate of the support decrease, leading to a reduction in catalyst activity.

[0174] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A methanation catalyst, characterized in that, The catalyst comprises a support, an active metal component, a first modifying agent, and a second modifying agent; wherein the support is SiO2 spherical particles; the active metal component is nickel; the first modifying agent is selected from at least one of Sc, Zr, Hf, Ti, and Y; the second modifying agent is a rare earth metal; and the average particle size of the active metal component is 8-20 nm. Based on the total amount of carrier, the sodium content in the carrier is not higher than 0.05 wt%, and the sulfur content is not higher than 50 ppm; After the catalyst was reduced at 300°C for 3 hours, the reduction degree of the active metal component was 80-95%. Based on the total amount of the catalyst, the content of the support is 48-76 wt%, the content of the active metal component (calculated as oxide) is 20-40 wt%, the content of the first modifying agent is 2-6 wt%, and the content of the second modifying agent is 2-6 wt%. The method for preparing the methanation catalyst includes the following steps: (1) The SiO2 support precursor is subjected to hydrothermal treatment and calcined to obtain the support; the support is SiO2 spherical particles; (2) The carrier is modified using a first modifying agent to obtain a modified carrier; (3) In the presence of a surfactant, the impregnation solution is contacted with the modified support, and then dried and calcined to obtain the methanation catalyst; The impregnation solution contains a soluble compound of an active metal component and a soluble compound of a second modifying agent. The conditions for the hydrothermal treatment are: reaction temperature of 60-120℃; time of 1-10h; In step (1), the calcination conditions are: calcination temperature of 400-800℃ and calcination time of 1-5h.

2. The catalyst according to claim 1, wherein, The average particle size of the active metal component is 10-18 nm.

3. The catalyst according to claim 1, wherein, The particle size of the carrier is 1-6 mm.

4. The catalyst according to claim 3, wherein, The particle size of the carrier is 3-5 mm.

5. The catalyst according to claim 1, wherein, The specific surface area of ​​the carrier is 250-480 m². 2 / g.

6. The catalyst according to claim 5, wherein, The specific surface area of ​​the carrier is 300-450 m². 2 / g.

7. The catalyst according to claim 1, wherein, The catalyst has a specific surface area of ​​150-380 m². 2 / g.

8. The catalyst according to claim 2, wherein, The catalyst has a specific surface area of ​​180-350 m². 2 / g.

9. The catalyst according to claim 1 or 2, wherein, The first modifying agent is selected from at least one of Y, Ti and Zr.

10. The catalyst according to claim 1, wherein, The second modifying agent is selected from at least one of La, Ce, Pr and Sm.

11. The catalyst according to claim 10, wherein, The second modifying agent is La and / or Ce.

12. The catalyst according to claim 1, wherein, Based on oxides, the mass ratio of the second modifying agent to the active metal component is 0.05-0.25:

1.

13. The catalyst according to claim 12, wherein, Based on oxides, the mass ratio of the second modifying agent to the active metal component is 0.07-0.2:

1.

14. A method for preparing a methanation catalyst, characterized in that, Includes the following steps: (1) The SiO2 support precursor is subjected to hydrothermal treatment and calcined to obtain the support; the support is SiO2 spherical particles; the hydrothermal treatment conditions are: reaction temperature of 60-120℃; time of 1-10h; the calcination conditions are: calcination temperature of 400-800℃; calcination time of 1-5h. Based on the total amount of carrier, the sodium content in the carrier is no more than 0.05 wt%, and the sulfur content is no more than 50 ppm; (2) The carrier is modified by using a first modifying agent to obtain a modified carrier; wherein the first modifying agent is selected from at least one of Sc, Zr, Hf, Ti and Y; (3) In the presence of a surfactant, the impregnation solution is contacted with the modified support, and then dried and calcined to obtain the methanation catalyst; The impregnation solution contains a soluble compound of an active metal component and a soluble compound of a second modifying agent. The active metal component is nickel, and the second modifying agent is a rare earth metal. The amounts of the support, the soluble compound of the active metal component, the soluble compound of the first modifying agent, and the soluble compound of the second modifying agent are such that, based on the total amount of catalyst, the content of the support is 48-76 wt%; the content of the active metal component (calculated as oxide) is 20-40 wt%; the content of the first modifying agent is 2-6 wt%; and the content of the second modifying agent is 2-6 wt%.

15. The preparation method according to claim 14, wherein, The hydrothermal treatment includes: mixing the SiO2 support precursor with water, and then performing hydrothermal treatment.

16. The preparation method according to claim 15, wherein, The volume ratio of water to the SiO2 support precursor is 1-3:

1.

17. The preparation method according to claim 16, wherein, The volume ratio of water to the SiO2 support precursor is 1.5-2.5:

1.

18. The preparation method according to claim 14, wherein, The conditions for the hydrothermal treatment are: reaction temperature of 70-90℃; time of 2-5h.

19. The preparation method according to claim 14, wherein, In step (1), the calcination conditions are: calcination temperature of 450-600℃ and calcination time of 1.5-3.5h.

20. The preparation method according to claim 14, wherein, In step (2), the modification process includes: impregnating or spraying the carrier with a solution of a soluble compound containing a first modifying agent, and then drying and calcining to obtain the modified carrier.

21. The preparation method according to claim 20, wherein, The calcination conditions include: a calcination temperature of 400-700℃ and a calcination time of 1-5 hours.

22. The preparation method according to claim 14, wherein, The first modifying agent is at least one of Y, Ti and Zr.

23. The preparation method according to claim 14, wherein, The surfactant is selected from at least one of anionic surfactants, amphoteric surfactants, and nonionic surfactants.

24. The preparation method according to claim 23, wherein, The surfactant is at least one of stearic acid, oleic acid, lauric acid, lecithin, dodecylaminopropionic acid, alkyl dimethyl betaine, fatty acid glycerides, polyols, Tween 60, and P123.

25. The preparation method according to claim 24, wherein, The surfactant is at least one of P123, oleic acid, and Tween 60.

26. The preparation method according to claim 14, wherein, The molar ratio of the surfactant to the total amount of the soluble compound of the active metal component (calculated as a metal element) and the soluble compound of the second modifying agent is 6 × 10⁻⁶. -6 -3×10 -5 :

1.

27. The preparation method according to claim 26, wherein, The molar ratio of the surfactant to the total amount of the soluble compound of the active metal component (calculated as a metal element) and the soluble compound of the second modifying agent is 1 × 10⁻⁶. -5 -2×10 -5 :

1.

28. The preparation method according to claim 14, wherein, The second modifying agent is selected from at least one of La, Ce, Pr and Sm.

29. The preparation method according to claim 28, wherein, The second modifying agent is La and / or Ce.

30. The preparation method according to claim 14, wherein, In the impregnation solution, the total concentration of soluble compounds of the active metal component and soluble compounds of the second modifying agent, calculated by metal element, is 0.6-1 kg / L.

31. The preparation method according to claim 14, wherein, The amounts of the soluble compound of the second modifying agent and the soluble compound of the active metal component are such that, in the prepared catalyst, the mass ratio of the second modifying agent to the active metal component, based on oxides, is 0.05-0.25:

1.

32. The preparation method according to claim 14, wherein, The amounts of the soluble compound of the second modifying agent and the soluble compound of the active metal component are such that, in the prepared catalyst, the mass ratio of the second modifying agent to the active metal component, based on oxides, is 0.07-0.2:

1.

33. The preparation method according to claim 14, wherein, The soluble compounds of the active metal component are selected from nickel nitrate and / or nickel acetate.

34. The preparation method according to claim 33, wherein, The soluble compound of the active metal component is nickel nitrate.

35. The preparation method according to claim 14, wherein, The soluble compounds of the first and second modifying agents are each independently selected from at least one of their respective nitrates, chlorides, and acetates.

36. The preparation method according to claim 35, wherein, The soluble compounds of the first and second modifying agents are each independently selected from their respective nitrates.

37. The preparation method according to claim 14, wherein, In step (3), the drying temperature is 80-140℃ and the time is 1-10h.

38. The preparation method according to claim 14, wherein, In step (3), the roasting temperature is 300-600℃ and the time is 1-10h.

39. The methanation catalyst prepared by the preparation method according to any one of claims 14-38.

40. The use of the methanation catalyst according to any one of claims 1-13 and 39 in the methanation reaction for crude hydrogen purification.

41. The application according to claim 40, wherein, The crude hydrogen purification methanation reaction is an ultra-low temperature crude hydrogen purification methanation reaction.

42. A methanation reaction method, the method comprising: Under methanation reaction conditions, the feed gas is contacted with a catalyst, wherein the catalyst is the methanation catalyst according to any one of claims 1-13 and 39.

43. The method according to claim 42, wherein, The raw material gas is crude hydrogen gas containing CO.

44. The method according to claim 43, wherein, The volume concentration of H2 in the crude hydrogen gas is 99-99.8%, and the volume concentration of CO is 2000-10000 ppm.

45. The method according to claim 44, wherein, The volume concentration of CO in the crude hydrogen gas is 3000-8000 ppm.

46. ​​The method according to claim 42, wherein, The contact takes place in a fixed-bed reactor.

47. The method according to claim 42, wherein, The methanation reaction conditions include: a reaction temperature of 130-350℃, a reaction pressure of 0-6 MPa, and a feed gas volume hourly space velocity of 1000-12000 h⁻¹. -1 .

48. The method according to claim 47, wherein, The methanation reaction conditions include: a reaction temperature of 150-250℃, a reaction pressure of 2-4 MPa, and a feed gas volume hourly space velocity of 6000-10000 h⁻¹. -1 .

49. The method according to claim 42, wherein, The method further includes reducing and activating the catalyst in the presence of hydrogen before the methanation reaction.

50. The method according to claim 49, wherein, The reduction activation conditions include: a reduction temperature of 200-600℃, a reduction time of 0.5-10 h, a hydrogen pressure of 0-2 MPa, and a hydrogen volume hourly space velocity of 300-3000 h⁻¹. -1 .

51. The method according to claim 50, wherein, The reduction activation conditions include: a reduction temperature of 260-350℃, a reduction time of 1-5 h, a hydrogen pressure of 0-1 MPa, and a hydrogen volume hourly space velocity of 500-2000 h⁻¹. -1 .

52. The method according to claim 51, wherein, The hydrogen pressure is 0-0.5 MPa.

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