Photocatalyst for methane dry reforming and preparation method and application thereof

Abstract

The invention relates to a photocatalyst for methane dry reforming and a preparation method and application thereof, in particular to the technical field of methane reforming, the photocatalyst for methane dry reforming comprises a carrier, 0.01-20 wt.% of active component nickel and 0.01-30 wt.% of auxiliaries in terms of rare earth elements, and the carrier comprises a mesoporous silica carrier. According to the photocatalyst for methane dry reforming provided by the invention, the active component nickel is in a high-dispersion state on the carrier and can maintain the high-dispersion state in a methane dry reforming reaction process, so that the catalyst shows high activity and high stability in the methane dry reforming process; therefore, methane dry reforming at low temperature is realized under photo-assisted catalysis, and high conversion rate of methane and carbon dioxide at low temperature is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of methane reforming, and in particular to a photocatalyst for methane dry reforming, a preparation method and uses thereof, and in particular to a rare earth-doped nickel-based photocatalyst for methane dry reforming, a preparation method and uses thereof. Background Art

[0002] At present, methane dry reforming is a process that converts methane and carbon dioxide into synthesis gas (CO and H2). This process can achieve energy conversion and greenhouse gas emission reduction. It is a strong endothermic process and usually needs to be carried out at high temperatures to obtain high methane and carbon dioxide conversion rates. However, under high temperature conditions, Ni-based catalysts experience the migration and merging of metallic nickel particles to form large particles of nickel. The sintered nickel particles promote the cracking of CH4 to form carbon deposits, causing the catalyst to deactivate, which in turn limits the practical application of Ni-based catalysts in the process of methane dry reforming.

[0003] CN117839699A discloses a nickel-based catalyst for dry reforming of methane, wherein the core-shell has a good confinement effect and can inhibit the agglomeration of nanoparticles to a certain extent, thereby making the catalyst have better stability. At the same time, the core-shell structure can also prevent the sintering of active metals, thereby improving 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 dry reforming of methane, wherein an active metal soluble salt, an auxiliary soluble salt, and a soluble fuel are configured into an aqueous solution, and then mixed with a carrier by an equal volume impregnation method, and then dried and calcined to obtain a target catalyst. The catalyst obtained by the method is applied to the dry reforming reaction of methane and exhibits excellent catalytic activity, anti-carbon deposition and anti-sintering properties. After a long period of reaction at a high space velocity, the catalyst activity can still reach a thermodynamic equilibrium value, and the H2 / CO ratio of the obtained synthesis gas (H2 / CO) is close to the theoretical value of 1. The catalyst preparation method is simple and has a good application prospect.

[0005] However, the methane dry reforming catalyst prepared by the above method still has the defects of high catalytic temperature, high energy consumption, and extremely low reaction activity at low temperatures, which limits its industrial application. Therefore, it is necessary to develop a new methane dry reforming catalyst that can achieve a high conversion rate of methane and carbon dioxide at low temperatures by lowering 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 to solve the defects of methane dry reforming catalysts, such as high catalytic temperature, high energy consumption and extremely low reaction activity at low temperatures.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a photocatalyst for dry reforming of methane, which comprises, by mass percentage, a carrier, an active component of nickel 0.01-20wt.%, an auxiliary agent in terms of rare earth elements 0.01-30wt.%, and the carrier comprises a mesoporous silica carrier.

[0009] The photocatalyst for methane dry reforming provided by the present invention has an active component, nickel, in a highly dispersed state on a carrier and can maintain a highly dispersed state during the methane dry reforming reaction, so that the catalyst exhibits high activity and high stability during the methane dry reforming process, thereby realizing methane dry reforming at a relatively low temperature under light-assisted catalysis, and ensuring that the dry reforming reaction can proceed at a low temperature. Since nickel of a nickel-based catalyst is prone to agglomeration at high temperatures, resulting in reduced reaction activity, light-assisted low-temperature reaction can weaken the agglomeration of nickel, thereby achieving a high conversion rate of methane and carbon dioxide at low temperatures.

[0010] As a preferred technical solution of the present invention, the auxiliary agent includes 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 a solvent are mixed, and then cyclohexane and alcohol are added to obtain a microemulsion; then a silicon source is added to the microemulsion to perform a hydrothermal reaction, and 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 auxiliary agent is one of Y, Sm or Ce or a combination of at least two of them. The rare earth element in the auxiliary agent is one of Y, Sm or Ce or a combination of at least two of them.

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

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

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

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

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

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

[0019] Preferably, the hydrothermal reaction time is 4-5 h.

[0020] Preferably, the calcination temperature is 500-600°C.

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

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

[0023] The carrier is mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined in sequence to obtain a photocatalyst for methane dry reforming.

[0024] As a preferred technical solution 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 chloride salts, nitrate salts, acetate salts, acetylacetonate salts, sulfate salts, and alcohol salts containing the corresponding rare earth elements.

[0026] As a preferred technical solution of the present invention, the mass ratio of the nickel salt to the 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°C.

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

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

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

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

[0032] As a preferred technical solution of the present invention, the space velocity GHSV of the reforming reaction is 10000-240000 mL·h -1 ·g cat -1 .

[0033] Preferably, the light used in the reforming reaction comprises sunlight having a light intensity of 10 suns to 40 suns.

[0034] As a preferred technical solution of the present invention, the temperature of the reforming reaction is 250-450°C.

[0035] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0036] The present invention loads rare earth metals and nickel onto silicon dioxide together. After calcination, the rare earth metal precursor forms rare earth metal oxide on the surface of silicon dioxide, and the nickel precursor forms nickel oxide particles. Since the interaction between nickel oxide and rare earth metal oxide is stronger than that between nickel oxide and silicon dioxide, the rare earth metal oxide inhibits the growth of nickel oxide particles and the formation of carbon deposits, thereby improving its activity and stability in the methane dry reforming reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The XRD spectra of the catalysts obtained in Examples 1-5 of the present invention;

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

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

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

[0041] Figure 5 This is a SEM image of the catalyst obtained in Example 4 of the present 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] Fig. 9 Schematic diagram showing the activity comparison of the catalysts obtained in Examples 2, 4 and 5 of the present invention.

[0046] The present invention is further described in detail below. However, the following examples are only 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 shall be subject to the claims. DETAILED DESCRIPTION

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

[0048] The present embodiment provides a photocatalyst for dry reforming of methane, which comprises, by mass percentage, a carrier, 0.01-20 wt.% of nickel as an active component, and 0.01-30 wt.% of an auxiliary agent as a rare earth element.

[0049] In the present invention, wt.% refers to mass percentage.

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

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

[0052] Wherein, the carrier comprises a mesoporous silica carrier.

[0053] Wherein, the auxiliary agent includes rare earth metal oxide.

[0054] 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.

[0055] The present invention introduces a rare earth metal additive, and the active metal nickel forms an alloy with the rare earth metal to increase the interaction between the active component nickel and the carrier, so that the catalyst exhibits higher catalytic activity, and the catalyst also has better stability.

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

[0057] In the present invention, the preparation process of the mesoporous silica carrier used is as follows:

[0058] Urea, hexadecyltrimethylammonium bromide and a solvent are mixed, and then cyclohexane and alcohol are added to obtain a microemulsion; a silicon source is then added to the microemulsion to carry out a hydrothermal reaction, and then a solid phase is obtained by solid-liquid separation, and the obtained solid phase is calcined to obtain a mesoporous silica carrier.

[0059] The solvent used in the preparation process of the mesoporous silica carrier includes water and other commonly used solvents in the art.

[0060] Wherein, the mass ratio of urea to hexadecyltrimethylammonium 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, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0061] Wherein, the solid-to-liquid ratio of the hexadecyltrimethylammonium bromide to the solvent is 1:(25-35) in 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, and other values ​​not listed within the range also meet the requirements.

[0062] Wherein, the solid-liquid ratio of the hexadecyltrimethylammonium bromide and cyclohexane is 1:(25-35) in 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, and other unlisted values ​​within the range also meet the requirements.

[0063] Wherein, the solid-to-liquid ratio of the hexadecyltrimethylammonium bromide and the alcohol is g / mL 1:(1.5-1.7), 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, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0064] Among them, 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, and other unlisted values ​​within the range also meet the requirements.

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

[0066] Wherein, the temperature of the hydrothermal reaction is 120-140°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C or 140°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0067] The hydrothermal reaction time is 4-5 h, for example, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h or 5 h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0068] The calcination temperature is 500-600°C, for example, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0069] The calcination time is 5.5-6.5 h, for example, 5.5 h, 5.6 h, 5.8 h, 6 h, 6.2 h, 6.4 h or 6.5 h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0070] In the present invention, when the carrier obtained by the preparation method provided by the present invention is used, the rare earth element in the auxiliary agent is selected to be 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 obtained catalyst has a significant catalytic effect, wherein the catalyst with Y, Sm or Ce as the auxiliary agent in the methane dry reforming reaction can produce CO at a rate of up to 75.95 mmol·g -1 ·h -1 The above is because the interaction between specific rare earth oxides, metallic nickel and the support can effectively weaken the agglomeration of nickel and is beneficial to the exposure of active sites.

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

[0072] The carrier is mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined in sequence 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] Illustratively, 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, and the like.

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

[0076] Illustratively, the auxiliary salt used can be selected from yttrium chloride, yttrium nitrate, yttrium carbonate, samarium chloride, samarium nitrate, samarium acetate, cerium nitrate, cerium chloride, cerium sulfate, and the like.

[0077] Wherein, 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, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0078] Wherein, the calcination temperature is 300-1000°C, for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0079] Wherein, the calcination is carried out under an inert atmosphere.

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

[0081] The calcination time is 2-8 hours, for example, 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, and other values ​​not listed within the range also meet the requirements.

[0082] In the present invention, the photocatalyst used for methane dry reforming can be optionally kept at 650-750°C for 0.5-5h for hydrogen in-situ reduction before the reforming reaction, and the space velocity GHSV is 10000-240000mL·h -1 ·g cat -1 .

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

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

[0085] In the present invention, argon or the like is used as a balance gas in the reforming reaction.

[0086] Wherein, the temperature of the reforming reaction is 250-450°C, for example, it can be 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C or 450°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

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

[0088] The GHSV of the reforming reaction is 10000-240000 mL·h -1 ·g cat -1 , for example, it can 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 240000mL·h -1 ·g cat -1 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0089] Among them, the light used in the reforming reaction includes sunlight with a light intensity of 10 suns to 40 suns, for example, it can be 10 suns, 15 suns, 20 suns, 25 suns, 30 suns, 35 suns or 40 suns, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0090] Furthermore, in order to illustrate the good conversion effect that can be achieved when the photocatalyst prepared by the present invention for methane dry reforming is reformed, an actual example is used for illustration, as follows:

[0091] The following examples are carried out in a continuous flow micro-reactor equipped with a gas mass flow meter, a program 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 uses a Pano A91 equipped with a TCD detector to analyze methane, hydrogen, carbon monoxide, carbon dioxide, oxygen, nitrogen, and low-carbon olefins, low-carbon alkanes, etc.;

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

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

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

[0095] 3. Add 10mmoL TEOS (tetraethyl silicate) and stir for 3h;

[0096] 4. Transfer to the reactor and react at 120°C for 4 hours;

[0097] 5. Wash and dry;

[0098] 6. Calcinate in a muffle furnace at 550°C for 6 h to obtain the KCC-1 carrier.

[0099] Example 1

[0100] This embodiment provides a reforming process using a photocatalyst for dry reforming of methane, which is as follows:

[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 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace and calcine at 550°C for 6 h under a nitrogen atmosphere to obtain the final catalyst.

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

[0104] The reorganization process is as follows:

[0105] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h-1 ·g cat -1 ), switched to reaction gas and started online analysis at 250°C 10 minutes later, using xenon lamp for illumination at a light intensity of 20 suns, then heated to 300°C 5 minutes later, and similarly, online analysis was performed 10 minutes after the temperature was raised to 300°C, and the catalytic data of the catalyst were tested at 5 temperature points: 250°C, 300°C, 350°C, 400°C, and 450°C.

[0106] The XRD spectra of the obtained catalyst are shown in Figure 1 , SEM photos are shown in Figure 2 The results of catalytic reforming reaction on the obtained catalyst are shown in Figure 7 .

[0107] Example 2

[0108] This embodiment provides a reforming process using a photocatalyst for dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0112] The reorganization process is as follows:

[0113] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), switched to reaction gas and started online analysis at 250°C 10 minutes later, using xenon lamp for illumination at a light intensity of 20 suns, then heated to 300°C 5 minutes later, and similarly, online analysis was performed 10 minutes after the temperature was raised to 300°C. The catalytic data of the catalyst were tested at 5 temperature points, namely 250°C, 300°C, 350°C, 400°C and 450°C.

[0114] The XRD spectra of the obtained catalyst are shown in Figure 1 , SEM photos are shown in Figure 3 The results of catalytic reforming reaction on the obtained catalyst are shown in 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 to be 1.08:1, that is, the atomic ratio of nickel to rare earth element is 10:7. Figure 1 , SEM photos are shown in 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 to be 1:0.84, that is, the atomic ratio of nickel to rare earth element is 10:9. Figure 1 , SEM photos are shown in Figure 5 The results of catalytic reforming reaction on the obtained catalyst are shown in Fig. 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 to be 1:0.69, that is, the atomic ratio of nickel to rare earth element is 10:11. The XRD spectrum of the obtained catalyst is shown in Figure 1 , SEM photos are shown in Figure 6 The results of catalytic reforming reaction on the obtained catalyst are shown in Fig. 9 .

[0121] XRD characterization

[0122] The XRD spectra of the catalysts obtained in Examples 1-5 are as follows: Figure 1 As shown in the figure, the peak at 2θ = 22° is the characteristic diffraction peak of amorphous SiO2, and the 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 carrier surface to a certain extent.

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

[0124] Table 1

[0125]

[0126] Example 6

[0127] This embodiment provides a reforming process using a photocatalyst for dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0131] The reorganization process is as follows:

[0132] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), and at the same time, a xenon lamp was used for illumination with a light intensity of 20 suns. 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 dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then rotate and evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0138] The reorganization process is as follows:

[0139] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), and at the same time, a xenon lamp was used for illumination with a light intensity of 20 suns. 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 dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0145] The reorganization process is as follows:

[0146] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), and at the same time, a xenon lamp was used for illumination with a light intensity of 20 suns. 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 dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0152] The reorganization process is as follows:

[0153] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), and at the same time, a xenon lamp was used for illumination with a light intensity of 20 suns. 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 dry reforming of methane, which is as follows:

[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 it, add 200 mg of KCC-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0159] The reorganization process is as follows:

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

[0161] Embodiment 11

[0162] This embodiment provides a reforming process using a photocatalyst for dry reforming of methane, which is as follows:

[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 it, add 200 mg of TS-1 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under argon atmosphere and calcine at 550°C for 6 h to obtain the final catalyst.

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

[0166] The reorganization process is as follows:

[0167] Ar was used to purge the hydrogen in the replacement system. After the replacement was completed, pure argon was switched to the reaction gas (CH4:CO2:Ar in the reaction raw gas = 4:4:2, the gas flow rate was 10 mL / min, and the space velocity was 12000 mL·h -1 ·g cat -1 ), and at the same time, a xenon lamp was used for illumination with a light intensity of 20 suns. 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 dry reforming of methane, which is as follows:

[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 it, add 200 mg of SBA-15 carrier, stir at room temperature 25°C for 2 h, and then evaporate to dryness in a constant temperature heated magnetic stirrer at 80°C; place it in a muffle furnace under helium atmosphere at 550°C for 6 h to obtain the final catalyst.

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

[0173] The reorganization process is as follows:

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

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

[0176] Further, this example provides an explanation of the reforming reaction at 700°C and 800°C, as follows:

[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 shown in Table 2.

[0180] Embodiment 14

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

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

[0183] Table 2

[0184]

[0185]

[0186] Comparative Example 1

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

[0188] Comparative Example 2

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

[0190] Comparative Example 3

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

[0192] The analysis results of the reforming reaction of the above comparative example at 450°C are shown in Table 3.

[0193] Table 3

[0194]

[0195] It can be seen from Table 1, Table 2 and Table 3 that in the scheme provided by the present invention, by doping with alkaline rare earth elements, the interaction between the rare earth oxide and the active component nickel after reduction weakens the agglomeration of nickel and exposes more active sites; KCC-1 is used as a carrier of the catalyst. Due to the special dendritic structure of KCC-1, the metallic nickel can be more evenly distributed on the carrier, further weakening the agglomeration of nickel and inhibiting the sintering of nickel; at the same time, the catalyst is used as a photothermal catalyst, and the introduction of light greatly reduces the reaction temperature of methane dry reforming. Since nickel is severely agglomerated under high temperature conditions, it can also reduce the agglomeration and sintering of nickel, thereby promoting the occurrence of dry reforming reaction.

[0196] It is stated that the present invention illustrates the detailed structural features of the present invention 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 improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, 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 are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to 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 further describe various possible combinations.

[0199] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A photocatalyst for methane dry reforming, characterized in that: The photocatalyst for methane dry reforming comprises, by weight percentage, a carrier, 0.01-20 wt.% of nickel as an active component, and 0.01-30 wt.% of an auxiliary agent as a rare earth element. The carrier is a mesoporous silica carrier.

2. The photocatalyst for methane dry reforming according to claim 1, characterized in that: The auxiliary agent includes rare earth metal oxide; 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.

3. The photocatalyst for methane dry reforming according to claim 1, characterized in that: The carrier is prepared by the following method: urea, hexadecyltrimethylammonium bromide and a solvent are mixed, and then cyclohexane and alcohol are added to obtain a microemulsion; then a silicon source is added to the microemulsion to perform a hydrothermal reaction, and then a solid phase is obtained by solid-liquid separation, and the obtained solid phase is calcined to obtain a mesoporous silica carrier, wherein 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); Preferably, the mass ratio of urea to hexadecyltrimethylammonium bromide is (0.55-0.65):1; Preferably, the solid-to-liquid ratio of the hexadecyltrimethylammonium bromide to the solvent is 1:(25-35) g / mL; Preferably, the solid-to-liquid ratio of hexadecyltrimethylammonium bromide to cyclohexane is 1:(25-35) in g / mL; Preferably, the solid-to-liquid ratio of the hexadecyltrimethylammonium bromide to the alcohol is 1:(1.5-1.7) in g / mL; Preferably, the molar mass ratio of the silicon source to urea is 10:(0.5-0.7) mmol / g; Preferably, the temperature of the hydrothermal reaction is 120-140°C; Preferably, the hydrothermal reaction time is 4-5h; Preferably, the calcination temperature is 500-600°C; Preferably, the calcination time is 5.5-6.5 hours.

4. A method for preparing a photocatalyst for methane dry reforming according to any one of claims 1 to 3, characterized in that: The preparation method comprises: The carrier is mixed with a solution containing nickel salt and auxiliary salt, and then evaporated and calcined in sequence to obtain a photocatalyst for methane dry reforming.

5. The preparation method according to claim 4, characterized in that: The nickel salt comprises one or a combination of at least two of nickel chloride, nickel nitrate, nickel acetate, nickel acetylacetonate or nickel sulfate; Preferably, the auxiliary salt includes one or a combination of at least two of chloride salts, nitrate salts, acetate salts, acetylacetonate salts, sulfate salts, and alcohol salts containing the corresponding rare earth elements.

6. The preparation method according to claim 4, characterized in that: The mass ratio of the nickel salt to the auxiliary salt in the solution is 1:(0.01-10).

7. The preparation method according to claim 4, characterized in that: The calcination temperature is 300-1000°C; Preferably, the calcination is carried out under an inert atmosphere; Preferably, the calcination time is 2-8 hours.

8. Use of a photocatalyst for methane dry reforming as claimed in any one of claims 1 to 3, characterized in that: The uses include: The photocatalyst for methane dry reforming is used to catalyze the reforming reaction of methane and carbon dioxide under the assistance of light.

9. The use according to claim 8, characterized in that The space velocity GHSV of the reforming reaction is 10000-240000 mL·h -1 ·g cat -1 ; Preferably, the light used in the reforming reaction comprises sunlight having a light intensity of 10 suns to 40 suns.

10. The use according to claim 8, characterized in that The temperature of the reforming reaction is 250-450°C.

Images