Photocatalyst for dry reforming of methane and method for its preparation and use

Abstract

The present application relates to a kind of photocatalyst for methane dry reforming and its preparation method and use, specifically relates to the field of methane reforming technology, the photocatalyst for methane dry reforming includes carrier with mass percentage content: active component nickel 0.01-20wt.%, auxiliary agent is 0.01-30wt.% with rare earth element, the carrier includes mesoporous silica carrier.The photocatalyst for methane dry reforming provided by the present application, active component nickel is in high dispersion state on carrier and can maintain high dispersion state in the process of methane dry reforming reaction, so that the catalyst in the process of methane dry reforming embodies high activity and high stability, so as to realize methane dry reforming at lower temperature under light-assisted catalysis, ensure the high conversion of methane and carbon dioxide at low temperature.

Description

Technical Field

[0001] This invention relates to the field of methane reforming technology, specifically to a photocatalyst for dry methane reforming, its preparation method and uses, and more particularly to a rare earth-doped nickel-based photocatalyst for dry methane reforming, its preparation method and uses. Background Technology

[0002] Currently, dry reforming of methane is a process that converts methane and carbon dioxide into syngas (CO and H2). This process achieves energy conversion and greenhouse gas emission reduction. It is a strongly endothermic process, typically requiring high temperatures to achieve high methane and carbon dioxide conversion rates. However, under high-temperature conditions, Ni-based catalysts experience the migration and coalescence of metallic nickel particles, forming large nickel particles. Sintering these large nickel particles promotes CH4 cracking, generating carbon deposits and causing catalyst deactivation. This limits the practical application of Ni-based catalysts in dry reforming of methane.

[0003] CN117839699A discloses a nickel-based catalyst for dry reforming of methane. Its core-shell structure exhibits a strong confinement effect, which can inhibit the aggregation of nanoparticles, thus improving the catalyst's stability. Simultaneously, the core-shell structure can prevent the sintering of the active metal, thereby enhancing catalytic stability and resistance to carbon deposition. However, the catalytic activity of the nickel-based core-shell structure is relatively low.

[0004] CN108906060A discloses a method for preparing a supported catalyst for methane dry reforming. The method involves preparing an aqueous solution of an active metal soluble salt, an auxiliary soluble salt, and a soluble fuel, then mixing these solutions with a support using an equal-volume impregnation method. Following drying and calcination, the target catalyst is obtained. The catalyst prepared by this method exhibits excellent catalytic activity, anti-coking, and anti-sintering properties in methane dry reforming reactions. Even after prolonged reactions at high space velocities, the catalyst activity still reaches thermodynamic equilibrium, and the H2 / CO ratio of the resulting syngas (H2 / CO) is close to the theoretical value of 1. This catalyst preparation method is simple and has good application prospects.

[0005] However, the methane dry reforming catalysts prepared by the above methods still have drawbacks such as high catalytic temperature, high energy consumption, and extremely low reaction activity at low temperatures, which limits their industrial applications. Therefore, it is necessary to develop a new methane dry reforming catalyst that can achieve high conversion rates of methane and carbon dioxide at low temperatures by reducing the temperature of the methane dry reforming catalytic reaction. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a photocatalyst for methane dry reforming, so as to solve the defects of methane dry reforming catalysts, which still have high catalytic temperature, high energy consumption and extremely low reaction activity at low temperature.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a photocatalyst for dry reforming of methane, the photocatalyst comprising, by weight percentage: a support, an active component of nickel of 0.01-20 wt.%, and an auxiliary agent of 0.01-30 wt.% based on rare earth elements, wherein the support comprises a mesoporous silica support.

[0009] The photocatalyst for methane dry reforming provided by this invention has a highly dispersed nickel active component on a support, which can maintain a highly dispersed state during the methane dry reforming reaction. This results in high activity and high stability of the catalyst during the methane dry reforming process, enabling methane dry reforming at lower temperatures under photo-assisted catalysis. This ensures that the dry reforming reaction can proceed at low temperatures. Since nickel in nickel-based catalysts tends to agglomerate at high temperatures, causing a decrease in reaction activity, photo-assisted low-temperature reaction can weaken nickel agglomeration and achieve high conversion rates of methane and carbon dioxide at low temperatures.

[0010] As a preferred embodiment of the present invention, the additives include rare earth metal oxides.

[0011] Preferably, the rare earth element in the additive includes one or a combination of at least two of La, Ce, Pr, Nd, Y, Sm, Eu, Gd, Dy or Er.

[0012] As a preferred technical solution of the present invention, the carrier is prepared by the following method: urea, hexadecyltrimethylammonium bromide and solvent are mixed, and then cyclohexane and alcohol are added to obtain a microemulsion; then a silicon source is added to the microemulsion, and a hydrothermal reaction is carried out; then a solid phase is obtained by solid-liquid separation, and the obtained solid phase is calcined to obtain a mesoporous silica carrier. At this time, the rare earth element in the additive is one or a combination of at least two of Y, Sm or Ce.

[0013] Preferably, the mass ratio of urea to hexadecyltrimethylammonium bromide is (0.55-0.65):1.

[0014] Preferably, the solid-liquid ratio of the hexadecyltrimethylammonium bromide and the solvent is 1:(25-35) g / mL.

[0015] Preferably, the solid-liquid ratio of hexadecyltrimethylammonium bromide and cyclohexane is 1:(25-35) g / mL.

[0016] Preferably, the solid-liquid ratio of the hexadecyltrimethylammonium bromide and the alcohol is 1:(1.5-1.7 g / mL).

[0017] Preferably, the molar mass ratio of the silicon source to urea (mmol / g) is 10:(0.5-0.7).

[0018] Preferably, the temperature of the hydrothermal reaction is 120-140℃.

[0019] Preferably, the hydrothermal reaction takes 4-5 hours.

[0020] Preferably, the roasting temperature is 500-600℃.

[0021] Preferably, the roasting time is 5.5-6.5 hours.

[0022] In a second aspect, the present invention provides a method for preparing a photocatalyst for dry reforming of methane as described in the first aspect, the method comprising:

[0023] The support was mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined sequentially to obtain a photocatalyst for methane dry reforming.

[0024] As a preferred embodiment of the present invention, the nickel salt includes one or a combination of at least two of nickel chloride, nickel nitrate, nickel acetate, nickel acetylacetonate, or nickel sulfate.

[0025] Preferably, the auxiliary salt includes one or a combination of at least two of the following: chloride salts, nitrate salts, acetate salts, acetylacetone salts, sulfate salts, and alcohol salts containing the corresponding rare earth elements.

[0026] As a preferred embodiment of the present invention, the mass ratio of nickel salt to auxiliary salt in the solution is 1:(0.01-10).

[0027] As a preferred technical solution of the present invention, the calcination temperature is 300-1000℃.

[0028] Preferably, the calcination is carried out under an inert atmosphere.

[0029] Preferably, the roasting time is 2-8 hours.

[0030] Thirdly, the present invention provides the use of a photocatalyst for dry reforming of methane as described in the first aspect, the use comprising:

[0031] The aforementioned photocatalyst for dry reforming of methane is used under light assistance to catalyze the reforming reaction of methane and carbon dioxide.

[0032] As a preferred embodiment of the present invention, the space velocity (GHSV) of the reforming reaction is 10,000-240,000 mL·h. -1 ·g cat -1 .

[0033] Preferably, the light used in the reforming reaction includes sunlight with an intensity of 10 to 40 solar masses.

[0034] As a preferred embodiment of the present invention, the temperature of the reforming reaction is 250-450℃.

[0035] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0036] This invention loads rare earth metals and nickel onto silicon dioxide. After calcination, the rare earth metal precursor forms rare earth metal oxides on the silicon dioxide surface, and the nickel precursor forms nickel oxide particles. Since the interaction between nickel oxide and rare earth metal oxides is stronger than that between nickel oxide and silicon dioxide, the rare earth metal oxides inhibit the growth of nickel oxide particles and the formation of carbon deposits, thereby improving their activity and stability in the dry reforming reaction of methane. Attached Figure Description

[0037] Figure 1 The XRD patterns of the catalysts obtained in Examples 1-5 of this invention are shown below.

[0038] Figure 2 Here is a SEM image of the catalyst obtained in Example 1 of this invention;

[0039] Figure 3 This is a SEM image of the catalyst obtained in Example 2 of the present invention;

[0040] Figure 4 Here is a SEM image of the catalyst obtained in Example 3 of this invention;

[0041] Figure 5 Here is a SEM image of the catalyst obtained in Example 4 of this invention;

[0042] Figure 6 This is a SEM image of the catalyst obtained in Example 5 of the present invention;

[0043] Figure 7 This is a schematic diagram of the activity of the catalyst obtained in Example 1 of the present invention;

[0044] Figure 8 This is a schematic diagram of the activity of the catalyst obtained in Example 2 of the present invention;

[0045] Figure 9 This is a schematic diagram showing the activity comparison of the catalysts obtained in Examples 2, 4 and 5 of the present invention.

[0046] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0047] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0048] This embodiment provides a photocatalyst for dry reforming of methane, which comprises, by mass percentage: a support, an active component of nickel (0.01-20 wt.%), and an auxiliary agent (0.01-30 wt.%) based on rare earth elements.

[0049] In this invention, wt.% refers to the percentage content by mass.

[0050] In this invention, the active component nickel in the photocatalyst used for methane dry reforming is 0.01-20 wt.% by mass percentage. For example, it can be 0.01 wt.%, 0.02 wt.%, 0.04 wt.%, 0.06 wt.%, 0.08 wt.%, 0.1 wt.%, 0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.%, 1 wt.%, 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, 14 wt.%, 16 wt.%, 18 wt.%, or 20 wt.%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0051] In this invention, the auxiliary agent in the photocatalyst used for dry reforming of methane, calculated by mass percentage and based on rare earth elements, is 0.01-30 wt.%, for example, it can be 0.01 wt.%, 0.02 wt.%, 0.04 wt.%, 0.06 wt.%, 0.08 wt.%, 0.1 wt.%, 0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.%, 1 wt.%, 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, 14 wt.%, 16 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, or 30 wt.%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0052] The carrier includes a mesoporous silica carrier.

[0053] The additives include rare earth metal oxides.

[0054] The rare earth elements in the additive include one or a combination of at least two of the following: La, Ce, Pr, Nd, Y, Sm, Eu, Gd, Dy, or Er.

[0055] This invention introduces rare earth metal additives. The active metal nickel forms an alloy with rare earth metals to increase the interaction between the active component nickel and the support, thereby enabling the catalyst to exhibit higher catalytic activity. At the same time, the catalyst also has better stability.

[0056] For example, the mesoporous silica carrier may be selected from commercially available carriers such as one or a combination of at least two of SBA-15, SBA-16, MCM-41, MCM-48 or S-1, or a mesoporous silica carrier prepared using existing technology.

[0057] The preparation process of the mesoporous silica support used in this invention is as follows:

[0058] Urea, hexadecyltrimethylammonium bromide and solvent were mixed, and then cyclohexane and alcohol were added to obtain a microemulsion. A silicon source was then added to the microemulsion and a hydrothermal reaction was carried out. After solid-liquid separation, a solid phase was obtained, and the obtained solid phase was calcined to obtain a mesoporous silica carrier.

[0059] The solvents used in the preparation of the mesoporous silica carrier include water and other commonly used solvents in this field.

[0060] The mass ratio of urea to cetyltrimethylammonium bromide is (0.55-0.65):1, for example, it can be 0.55:1, 0.56:1, 0.58:1, 0.6:1, 0.62:1, 0.64:1 or 0.65:1, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0061] Wherein, the solid-liquid ratio of the hexadecyltrimethylammonium bromide and the solvent is 1:(25-35) g / mL, for example, it can be 1:25, 1:26, 1:28, 1:30, 1:32, 1:34 or 1:35, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0062] The solid-liquid ratio of hexadecyltrimethylammonium bromide and cyclohexane is 1:(25-35) g / mL, for example, it can be 1:25, 1:26, 1:28, 1:30, 1:32, 1:34 or 1:35, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0063] The solid-liquid ratio of hexadecyltrimethylammonium bromide and alcohol is 1:(1.5-1.7) g / mL, for example, it can be 1:1.5, 1:1.52, 1:1.54, 1:1.56, 1:1.58, 1:1.6, 1:1.62, 1:1.64, 1:1.66, 1:1.68 or 1:1.7, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0064] The molar mass ratio of the silicon source to urea (mmol / g) is 10:(0.5-0.7), for example, it can be 10:0.5, 10:0.52, 10:0.54, 10:0.56, 10:0.58, 10:0.6, 10:0.62, 10:0.64, 10:0.66, 10:0.68 or 10:0.7, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0065] The material obtained after adding the silicon source is stirred.

[0066] The temperature of the hydrothermal reaction is 120-140℃, for example, it can be 120℃, 122℃, 124℃, 126℃, 128℃, 130℃, 132℃, 134℃, 136℃, 138℃ or 140℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0067] The hydrothermal reaction time is 4-5 hours, for example, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0068] The roasting temperature is 500-600℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0069] The roasting time is 5.5-6.5h, for example, it can be 5.5h, 5.6h, 5.8h, 6h, 6.2h, 6.4h or 6.5h, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0070] In this invention, when the support obtained by the preparation method provided by this invention is selected, and the rare earth element in the auxiliary agent is one or a combination of at least two of Y, Sm, or Ce, and the molar ratio of the active component nickel to the rare earth element is 10:(5-8), the resulting catalyst has a significant catalytic effect. Specifically, the catalyst using Y, Sm, or Ce as auxiliary agents can achieve a CO generation rate of 75.95 mmol·g in the dry reforming reaction of methane. -1 ·h -1 This is because the interaction between specific rare earth oxides, metallic nickel, and the support can effectively reduce nickel aggregation and facilitate the exposure of active sites.

[0071] Furthermore, this embodiment provides a method for preparing the aforementioned photocatalyst for methane dry reforming, the method comprising:

[0072] The support was mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined sequentially to obtain a photocatalyst for methane dry reforming.

[0073] The nickel salt includes one or a combination of at least two of nickel chloride, nickel nitrate, nickel acetate, nickel acetylacetonate, or nickel sulfate.

[0074] For example, the combination of nickel salts may be selected as a combination of nickel chloride and nickel nitrate, a combination of nickel nitrate and nickel acetate, a combination of nickel acetate and nickel acetylacetonate, a combination of nickel acetylacetonate and nickel sulfate, etc.

[0075] The auxiliary salt includes one or a combination of at least two of the following: chloride salts, nitrate salts, acetate salts, acetylacetone salts, sulfate salts, and alcohol salts containing the corresponding rare earth elements.

[0076] For example, the auxiliary salt used may be selected from yttrium chloride, yttrium nitrate, yttrium carbonate, samarium chloride, samarium nitrate, samarium acetate, cerium nitrate, cerium chloride, cerium sulfate, etc.

[0077] The mass ratio of nickel salt to auxiliary salt in the solution is 1:(0.01-10), for example, it can be 1:0.01, 1:0.02, 1:0.04, 1:0.06, 1:0.08, 1:0.1, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0078] The roasting temperature is 300-1000℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0079] The calcination is carried out under an inert atmosphere.

[0080] In this invention, the inert atmosphere includes nitrogen, helium, neon, argon, and other commonly used inert atmospheres in the art.

[0081] The roasting time is 2-8 hours, for example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0082] In this invention, the photocatalyst used for dry reforming of methane may optionally undergo in-situ hydrogen reduction at 650-750°C for 0.5-5 hours before the reforming reaction, with a space velocity (GHSV) of 10,000-240,000 mL·h. -1 ·g cat -1 .

[0083] Furthermore, the present invention provides the aforementioned use of the photocatalyst for methane dry reforming, the use including:

[0084] The aforementioned photocatalyst for dry reforming of methane was used under light assistance to catalyze the reforming reaction of methane and carbon dioxide.

[0085] In this invention, argon or similar gas is used as the equilibrium gas in the reforming reaction.

[0086] The reforming reaction temperature is 250-450℃, for example, it can be 250℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃ or 450℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0087] For example, the volume ratio of methane to carbon dioxide in the reforming reaction is 1:1.

[0088] The space velocity (GHSV) of the reforming reaction is 10,000-240,000 mL·h. -1 ·g cat -1 For example, it could be 10000 mL·h -1·g cat -1 20000mL·h -1 ·g cat -1 40000mL·h -1 ·g cat -1 80000mL·h -1 ·g cat -1 100000mL·h -1 ·g cat -1 120000mL·h -1 ·g cat -1 140000mL·h -1 ·g cat -1 160000mL·h -1 ·g cat -1 180000mL·h -1 ·g cat -1 200000mL·h -1 ·g cat -1 220000mL·h -1 ·g cat -1 Or 240000 mL·h -1 ·g cat -1 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0089] The light used in the reforming reaction includes sunlight with an intensity of 10 to 40 solar radii, such as 10, 15, 20, 25, 30, 35, or 40 solar radii, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0090] Furthermore, to illustrate the excellent conversion effect achievable by the photocatalyst prepared in this invention for dry reforming of methane, a practical example is provided as follows:

[0091] The following example was conducted in a continuous flow microreactor equipped with a gas mass flow meter, a programmed temperature control system, and an online product analysis chromatograph (the tail gas of the reaction gas is directly connected to the quantitative valve of the chromatograph for periodic real-time sampling and analysis); the online product analysis used a Panno A91 chromatograph equipped with a TCD detector to analyze methane, hydrogen, carbon monoxide, carbon dioxide, oxygen, nitrogen, and low-carbon olefins and low-carbon alkanes.

[0092] The KCC-1 carrier used in the following examples was obtained according to the preparation method provided by the present invention, and the process is as follows:

[0093] 1. Dissolve 0.6g of urea and 1g of CTAB in 30mL of water;

[0094] 2. Add 30 mL of cyclohexane and 1.6 mL of n-hexanol to the above microemulsion;

[0095] 3. Add 10 mmol of TEOS (tetraethyl silicate) and stir for 3 hours;

[0096] 4. Transfer to a reaction vessel and react at 120℃ for 4 hours;

[0097] 5. Wash and dry;

[0098] 6. Calcination at 550℃ for 6 hours in a muffle furnace yielded the KCC-1 carrier.

[0099] Example 1

[0100] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0101] The catalyst preparation process is as follows:

[0102] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, add 5 mL of deionized water to dissolve it, then add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, and then evaporate to dryness in a magnetic stirrer at 80 °C; calcine at 550 °C for 6 h in a muffle furnace under nitrogen atmosphere to obtain the final catalyst.

[0103] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0104] The restructuring process is as follows:

[0105] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h).-1 ·g cat -1 After switching to the reaction gas for 10 minutes, online analysis was started at 250℃, while simultaneously irradiating with a xenon lamp at an intensity of 20 solar flares. The temperature was then increased to 300℃ after 5 minutes, and online analysis was performed again 10 minutes after reaching 300℃. Catalytic data were tested at five temperature points: 250℃, 300℃, 350℃, 400℃, and 450℃.

[0106] For details, see the XRD pattern of the obtained catalyst. Figure 1 For SEM photos, please see [link / reference]. Figure 2 For details of the catalytic reforming reaction using the obtained catalyst, please refer to [link to relevant documentation]. Figure 7 .

[0107] Example 2

[0108] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0109] The catalyst preparation process is as follows:

[0110] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0457 g of Y(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, then add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, then evaporate to dryness in a magnetic stirrer at 80 °C; calcine at 550 °C for 6 h in a muffle furnace under a helium atmosphere to obtain the final catalyst.

[0111] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0112] The restructuring process is as follows:

[0113] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 After switching to the reaction gas for 10 minutes, online analysis was started at 250℃, while simultaneously irradiating with a xenon lamp at an intensity of 20 solar flares. The temperature was then increased to 300℃ after 5 minutes, and online analysis was performed again 10 minutes after reaching 300℃. Catalytic data were tested at five temperature points: 250℃, 300℃, 350℃, 400℃, and 450℃.

[0114] For details, see the XRD pattern of the obtained catalyst. Figure 1 For SEM photos, please see [link / reference]. Figure 3 For details of the catalytic reforming reaction using the obtained catalyst, please refer to [link to relevant documentation]. Figure 8 .

[0115] Example 3

[0116] The only difference from Example 2 is that the mass ratio of nickel salt to rare earth salt is controlled at 1.08:1, i.e., the atomic ratio of nickel to rare earth elements is 10:7. The XRD pattern of the obtained catalyst is detailed below. Figure 1 For SEM photos, please see [link / reference]. Figure 4 .

[0117] Example 4

[0118] The only difference from Example 2 is that the mass ratio of nickel salt to rare earth salt is controlled at 1:0.84, i.e., the atomic ratio of nickel to rare earth elements is 10:9. The XRD pattern of the obtained catalyst is detailed below. Figure 1 For SEM photos, please see [link / reference]. Figure 5 For details of the catalytic reforming reaction using the obtained catalyst, please refer to [link to relevant documentation]. Figure 9 .

[0119] Example 5

[0120] The only difference from Example 2 is that the mass ratio of nickel salt to rare earth salt is controlled at 1:0.69, i.e., the atomic ratio of nickel to rare earth elements is 10:11. The XRD pattern of the obtained catalyst is detailed below. Figure 1 For SEM photos, please see [link / reference]. Figure 6 For details of the catalytic reforming reaction using the obtained catalyst, please refer to [link to relevant documentation]. Figure 9 .

[0121] XRD characterization

[0122] The XRD patterns of the catalysts obtained in Examples 1-5 are as follows: Figure 1 As shown in the figure, the peak at 2θ = 22° is a characteristic diffraction peak of amorphous SiO2, while characteristic diffraction peaks of NiO appear at 2θ = 37.3°, 43.3°, and 62.9° [PDF#97-002-8834]. Compared with the Ni / KCC-1 catalyst, the intensity of the characteristic diffraction peaks of the Ni-based catalyst doped with metal additives is significantly reduced, indicating that the doping of metal additives can improve the dispersion of Ni particles on the support surface to a certain extent.

[0123] The online analysis results of the reforming reaction in Examples 1-5 above at 450°C are detailed in Table 1.

[0124] Table 1

[0125]

[0126] Example 6

[0127] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0128] The catalyst preparation process is as follows:

[0129] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0292 g of La(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, then add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, and then evaporate to dryness in a magnetic stirrer at 80 °C; calcine in a muffle furnace at 550 °C for 6 h under a helium atmosphere to obtain the final catalyst.

[0130] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0131] The restructuring process is as follows:

[0132] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0133] Example 7

[0134] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0135] The catalyst preparation process is as follows:

[0136] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0370 g of Eu(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, then evaporate to dryness in a magnetic stirrer at 80 °C; calcine in a muffle furnace at 550 °C for 6 h under a helium atmosphere to obtain the final catalyst.

[0137] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0138] The restructuring process is as follows:

[0139] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0140] Example 8

[0141] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0142] The catalyst preparation process is as follows:

[0143] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0371 g of Sm(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, then evaporate to dryness in a magnetic stirrer at 80 °C; calcine in a muffle furnace at 550 °C for 6 h under a helium atmosphere to obtain the final catalyst.

[0144] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0145] The restructuring process is as follows:

[0146] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0147] Example 9

[0148] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0149] The catalyst preparation process is as follows:

[0150] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0379 g of Pr(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, then evaporate to dryness in a magnetic stirrer at 80 °C; calcine in a muffle furnace at 550 °C for 6 h under a helium atmosphere to obtain the final catalyst.

[0151] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0152] The restructuring process is as follows:

[0153] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0154] Example 10

[0155] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0156] The catalyst preparation process is as follows:

[0157] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0380 g of Ce(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, add 200 mg of KCC-1 support, stir at room temperature (25 °C) for 2 h, then evaporate to dryness in a magnetic stirrer at 80 °C; calcine in a muffle furnace at 550 °C for 6 h under a helium atmosphere to obtain the final catalyst.

[0158] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0159] The restructuring process is as follows:

[0160] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0161] Example 11

[0162] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0163] The catalyst preparation process is as follows:

[0164] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0457 g of Y(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, then add 200 mg of TS-1 support, stir at room temperature (25 °C) for 2 h, and then evaporate to dryness by rotation in a magnetic stirrer at 80 °C; calcine at 550 °C for 6 h in an argon atmosphere in a muffle furnace to obtain the final catalyst.

[0165] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0166] The restructuring process is as follows:

[0167] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0168] Example 12

[0169] This embodiment provides a reforming process using a photocatalyst for methane dry reforming, as detailed below:

[0170] The catalyst preparation process is as follows:

[0171] Weigh 0.495 g of Ni(NO3)2·6H2O into a beaker, weigh 0.0457 g of Y(NO3)3·6H2O, add 5 mL of deionized water to dissolve them, then add 200 mg of SBA-15 support, stir at room temperature (25 °C) for 2 h, and then evaporate to dryness by rotation in a magnetic stirrer at 80 °C; calcine at 550 °C for 6 h in a muffle furnace under a helium atmosphere to obtain the final catalyst.

[0172] Take 50 mg of the granulated finished catalyst and reduce it with 100% H2 before dry reforming with methane (total flow rate of 10 mL / min, reduction temperature from room temperature to 700 °C and held at 700 °C for 1 h, heating rate of 10 °C / min).

[0173] The restructuring process is as follows:

[0174] The hydrogen in the replacement system was purged with Ar. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar = 4:4:2 in the reactant gas, gas flow rate of 10 mL / min, space velocity of 12000 mL·h). -1 ·g cat -1 Simultaneously, a xenon lamp was used for illumination at an intensity of 20 solar flares. After switching to the reaction gas for 10 minutes, online analysis was started at 450°C.

[0175] The analytical results of the reforming reaction in Examples 6-12 above at 450°C are detailed in Table 2.

[0176] Furthermore, this embodiment provides a description of the reforming reaction at 700°C and 800°C, as detailed below:

[0177] Example 13

[0178] The difference from Example 3 is that the reforming reaction is carried out at 700°C.

[0179] The analysis results are detailed in Table 2.

[0180] Example 14

[0181] The difference from Example 3 is that the reforming reaction is carried out at 800°C.

[0182] The analysis results are detailed in Table 2.

[0183] Table 2

[0184]

[0185]

[0186] Comparative Example 1

[0187] The only difference from Example 3 is that the carrier is replaced with an equal amount of mesoporous aluminum foam carrier.

[0188] Comparative Example 2

[0189] The only difference from Example 3 is that the carrier is replaced with an equal amount of γ-alumina carrier.

[0190] Comparative Example 3

[0191] The only difference from Example 3 is that no light is used during the reforming reaction.

[0192] The analytical results of the reforming reaction of the above comparative examples at 450℃ are detailed in Table 3.

[0193] Table 3

[0194]

[0195] As shown in Tables 1, 2, and 3, in the solution provided by this invention, the doping of alkaline rare earth elements weakens the agglomeration of nickel by the interaction between the rare earth oxides and the active component nickel after reduction, exposing more active sites. Using KCC-1 as a catalyst support, the special dendritic structure of KCC-1 allows metallic nickel to be distributed more uniformly on the support, further weakening nickel agglomeration and inhibiting nickel sintering. At the same time, as a photothermal catalyst, the introduction of light greatly reduces the reaction temperature of methane dry reforming. Since nickel agglomerates severely under high temperature conditions, this also reduces nickel agglomeration and sintering, promoting the occurrence of dry reforming reaction.

[0196] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0197] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0198] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0199] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. The use of a photocatalyst for dry reforming of methane, characterized in that, The uses include: A photocatalyst for dry reforming of methane is used to catalyze the reforming reaction of methane and carbon dioxide under light assistance; the light used in the reforming reaction is sunlight with an intensity of 10 to 40 solar masses; the temperature of the reforming reaction is 250 to 450°C. The photocatalyst used for dry reforming of methane in the described application comprises, by mass percentage: a support, an active component of nickel 0.01-20 wt.%, and an auxiliary agent including rare earth metal oxides, calculated as rare earth elements 0.01-30 wt.%, wherein the support is a mesoporous silica support; The preparation method of the photocatalyst includes: The support was mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined sequentially to obtain a photocatalyst for methane dry reforming.

2. The use as described in claim 1, characterized in that, The rare earth elements in the additive include one or a combination of at least two of the following: La, Ce, Pr, Nd, Y, Sm, Eu, Gd, Dy, or Er.

3. The use as described in claim 1, characterized in that, The carrier is prepared by the following method: urea, hexadecyltrimethylammonium bromide and solvent are mixed, then cyclohexane and alcohol are added to obtain a microemulsion; then a silicon source is added to the microemulsion, and a hydrothermal reaction is carried out. After solid-liquid separation, a solid phase is obtained, and the obtained solid phase is calcined to obtain a mesoporous silica carrier. At this time, the rare earth element in the additive is one or a combination of at least two of Y, Sm or Ce, and the molar ratio of the active component nickel to the rare earth element is 10:(5-8).

4. The use as described in claim 3, characterized in that, The mass ratio of urea to cetyltrimethylammonium bromide is (0.55-0.65):

1.

5. The use as described in claim 3, characterized in that, The solid-liquid ratio of the hexadecyltrimethylammonium bromide and the solvent is 1:(25-35) g / mL.

6. The use as described in claim 3, characterized in that, The solid-liquid ratio of hexadecyltrimethylammonium bromide and cyclohexane is 1:(25-35) g / mL.

7. The use as described in claim 3, characterized in that, The solid-liquid ratio of the hexadecyltrimethylammonium bromide and the alcohol is 1:(1.5-1.7 g / mL).

8. The use as described in claim 3, characterized in that, The molar mass ratio of the silicon source to urea (mmol / g) is 10:(0.5-0.7).

9. The use as described in claim 3, characterized in that, The temperature of the hydrothermal reaction is 120-140℃.

10. The use as described in claim 3, characterized in that, The hydrothermal reaction takes 4-5 hours.

11. The use as described in claim 3, characterized in that, The calcination temperature in the preparation method of the carrier is 500-600℃.

12. The use as described in claim 3, characterized in that, The calcination time in the preparation method of the carrier is 5.5-6.5 h.

13. The use as described in claim 1, characterized in that, The nickel salt includes one or a combination of at least two of nickel chloride, nickel nitrate, nickel acetate, nickel acetylacetonate, or nickel sulfate.

14. The use as described in claim 1, characterized in that, The auxiliary salt includes one or a combination of at least two of the following: chloride salts, nitrate salts, acetate salts, acetylacetone salts, sulfate salts, and alcohol salts containing the corresponding rare earth elements.

15. The use as described in claim 1, characterized in that, The mass ratio of nickel salt to auxiliary salt in the solution is 1:(0.01-10).

16. The use as described in claim 1, characterized in that, The calcination temperature in the preparation method of the photocatalyst is 300-1000℃.

17. The use as described in claim 1, characterized in that, In the preparation method of the photocatalyst, calcination is carried out under an inert atmosphere.

18. The use as described in claim 1, characterized in that, The calcination time in the preparation method of the photocatalyst is 2-8 hours.

19. The use as described in claim 1, characterized in that, The space velocity (GHSV) of the reforming reaction is 10,000-240,000. .

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