Preparation method and application of methane dry reforming catalyst with strong stability and strong anti-carbon deposition

Abstract

This invention discloses a method for preparing a highly stable and strongly anti-carbon-deposition methane dry reforming catalyst and its application, belonging to the field of energy chemical engineering and environmental catalysis technology. The catalyst uses Ni as the active component, Ca as a promoter, and silicate as a support, with the following total mass ratio: Ni (10wt%), Ca promoter (10wt%), and silicate support (80wt%). The raw materials selected are nickel nitrate hexahydrate, calcium nitrate tetrahydrate, and tetraethyl orthosilicate as the nickel source, calcium source, and silicon source, respectively, with CTAB as the template agent. Nickel and calcium nitrates are dissolved in deionized water to prepare a metal salt solution; CTAB and NaOH are dissolved in water and stirred in a 60°C water bath until clarified; the metal salt solution is added dropwise, stirred at 60°C for 30 min, and then tetraethyl orthosilicate is added, stirred at room temperature for 1 h; the mixture is transferred to a hydrothermal reactor and hydrothermally heated at 110°C for 48 h. After cooling, the precipitate is washed by centrifugation and dried to obtain a powder, which is then calcined, cooled, pressed into tablets, and sieved to 20-40 mesh to obtain the Ni-CaSiO3 catalyst. The preparation process of this invention is simple and controllable, with low production cost. The resulting catalyst has excellent reaction stability and anti-carbon deposition ability, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition. Specifically, it is a catalyst used to convert two major greenhouse gases, CO2 and CH4, into syngas (CO and H2) in a 1:1 ratio through a reforming reaction, belonging to the fields of energy and chemical engineering and environmental catalysis. Background Technology

[0002] Methane dry reforming technology is not only a key technology for addressing current environmental pressures, but also a major support for my country's green and low-carbon development strategy. The core value of this process lies in the flexibility of its products: by controlling the reaction, the ratio of hydrogen to carbon monoxide in the resulting syngas can be adjusted within a certain range, thus meeting the demand for clean fuels and serving as a key platform feedstock to achieve the recycling of carbon resources.

[0003] Compared to traditional steam reforming and partial oxidation syngas production processes, dry methane reforming offers several significant advantages. Its core advantage in greenhouse gas utilization lies in its ability to directly and synergistically convert CO2 and CH4, the two main greenhouse gases, into syngas with an H2 / CO ratio close to 1:1. This process achieves "waste-to-waste treatment," avoiding the raw material or emission shortcomings of other technologies (such as steam reforming, which is accompanied by high carbon emissions, and CO2 hydrogenation, which relies on expensive green hydrogen). Its products are ideal feedstocks for high-value chemical production such as Fischer-Tropsch synthesis and methanol production, combining significant carbon reduction benefits with technological feasibility, making it a key pathway to building a circular carbon economy.

[0004] Methane dry reforming (DRM) requires relatively high reaction temperatures. Nickel is a commonly used transition metal catalyst. Among methane dry reforming catalysts, Ni-based catalysts face two major deactivation problems in the DRM reaction: agglomeration and sintering of active Ni particles, and surface carbon deposition caused by deep cracking and disproportionation reactions. Zhang et al. (Dryreforming of methane over Ni / SiO2 catalysts: Role of support structure properties, Fuel, 2023(340): 127490) impregnated nickel with inverted conical mesoporous silica spheres (MSS), ordered mesoporous silica (MCM-41), and commercial silica (SiO). The results showed that the carbon deposition of the three catalysts was severe, leading to a significant reduction in activity. Jing et al. (Reforming of CH4 with CO2 and O2 to produce syngasover CaO modified Ni / SiO2 catalysts in a fluidized bed reactor. React KinetCatal L, 2004(83):291) reported that CaO-modified Ni / SiO2 catalysts exhibited more stable performance. This is because Ca promotes the dispersion of Ni on the catalyst surface and enhances the interaction between the metal and the support, preventing the agglomeration of Ni particles at high temperatures. This fully demonstrates that Ca is highly beneficial for Ni-based catalysts.

[0005] This patent provides a green preparation method and application of a highly stable, strongly anti-carbon-deposition silicate catalyst. The design concept of this patent is to prepare a green silicate catalyst with high stability, strong anti-carbon-deposition properties, and strong metal-support interaction through a simple preparation method and low-cost raw materials. According to literature reports, the impregnation method is relatively convenient for preparing Ni-based catalysts. Therefore, previous studies used the impregnation method to prepare Ni / SiO2 catalysts, but this method suffered from poor dispersion of the active metal and insufficient active sites, resulting in low catalytic activity and easy carbon deposition and deactivation during the reaction. Literature reports show that the promoter Ca can increase the dispersion of the active metal, and the alkaline earth metal Ca can reduce the Lewis acidity of the catalyst, improving its stability and activity. Therefore, this patent attempts to introduce Ca as a promoter during the impregnation process to increase the dispersion of the active metal Ni and the metal-support interaction. Experimental results show that the addition of Ca promoter improves the catalyst's anti-carbon-deposition performance and stability to some extent, but its effect on improving catalytic activity is limited. Therefore, we further optimized the synthesis strategy by using a hydrothermal method to anchor the active metal Ni and the auxiliary metal Ca within a silica framework to form a unique silicate structure. This significantly enhanced the interaction between the metal and the support, effectively inhibiting the migration and sintering of the active components, and simultaneously improving the catalyst's resistance to carbon deposition. Experimental results show that the prepared Ni-CaSiO3 catalyst exhibits excellent stability and resistance to carbon deposition in catalytic reactions, demonstrating promising application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing and applying a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition. This method has the advantages of simple preparation process, easy operation, and low cost. Firstly, using inexpensive tetraethyl orthosilicate, with Ni as the active component and Ca as the auxiliary agent, and tetraethyl orthosilicate as the framework raw material, a silicate catalyst Ni-CaSiO3 is prepared by a hydrothermal method. By doping with the auxiliary agent Ca, the particle size of Ni particles and the interaction force between the metal and the support are controlled, thereby improving the catalyst's stability and resistance to carbon deposition. In the hydrothermal method, all components are mixed simultaneously in the same high-temperature reactor, resulting in a highly uniform distribution of the active component and a strong interaction between the active component and the support. The dispersed active component's adsorption capacity for CH4 and CO2 further enhances the catalyst's stability and resistance to carbon deposition. The first problem solved by this invention is the development of a highly active catalyst with independent intellectual property rights; the second problem solved is the control of Ni particle size and the interaction force between the metal and the support to achieve strong stability and resistance to carbon deposition at 700 °C.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing and applying a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition includes the following steps:

[0009] (1) Weigh the active components according to the stoichiometric ratio (with the total mass of the support and active component Ni being 100%, the mass percentage of active component Ni in the catalyst being 10%, the mass percentage of the promoter being 10%, and the total mass of the support being 80%). Among these, nickel nitrate hexahydrate (Ni(NO3)2·6H2O) is the source of the active component Ni, and tetraethyl orthosilicate (C8H2O) is the source of the active component Ni. 20 Ni(NO3)2·6H2O was used as the Si source and calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) was used as the Ca source. Ni(NO3)2·6H2O and Ca(NO3)2·4H2O were added to deionized water and stirred until completely dissolved to obtain a transparent solution.

[0010] (2) Weigh a certain amount of CTAB and add it to deionized water, then add a certain amount of NaOH solid, and place it on a 60 ℃ constant temperature water bath and stir until the solution is clear;

[0011] (3) Add the metal salt solution in (1) dropwise to the clear solution in (2) using a dropper, and stir the mixture in a 60 ℃ constant temperature water bath for 30 min.

[0012] (4) Weigh the C8H obtained in step (1) 20 O4Si was added to the green slurry obtained in step (3); the beaker was sealed with plastic wrap and then transferred to room temperature and stirred for 1 h.

[0013] (5) The green suspension obtained in step (4) is transferred into a high-pressure reactor lined with polytetrafluoroethylene and placed in a constant temperature drying oven at 110°C for 48 h.

[0014] (6) After cooling (5) to room temperature, take it out, pour the suspension into a centrifuge tube, wash it repeatedly with deionized water three times to obtain a green precipitate;

[0015] (7) Place the powder obtained in step (6) in a constant temperature drying oven and dry overnight to obtain green powder;

[0016] (8) Place the powder obtained in step (7) in a muffle furnace, calcine it, cool it naturally to room temperature, press it into tablets, and grind it into a catalyst with a mesh size of 20-40 to obtain a catalyst for the dry reforming of methane to produce syngas.

[0017] According to the above scheme, the catalyst mass is 100%, and the active component Ni mass percentage content is 10%.

[0018] According to the above scheme, the temperature of the closed thermostatic magnetic stirrer is 60 ℃ for 30 min.

[0019] According to the above scheme, the hydrothermal method conditions are 110 ℃ and 48 h;

[0020] According to the above scheme, the drying temperature is 110 ℃;

[0021] According to the above scheme, the drying time is 11-13 hours;

[0022] According to the above scheme, the activation method is calcination.

[0023] According to the above scheme, the calcination temperature is 700 ℃;

[0024] According to the above scheme, the roasting time is 4 hours.

[0025] The present invention also provides the application of the methane dry reforming syngas catalyst prepared by any of the above technical solutions in carbon dioxide conversion.

[0026] Compared with the prior art, the beneficial technical effects of the technical solution of this invention application are as follows:

[0027] 1. The hydrothermal method of the present invention prepares Ca-doped Ni-based silicate catalyst Ni-CaSiO3 for CH4 / CO2 reforming reaction. The stability of the catalyst is significantly improved compared with that of Ni-based catalysts prepared by impregnation. At 700 °C, the initial conversion rates of methane and carbon dioxide reach 79% and 80%, respectively. The carbon deposition after 20 h of reaction is only 0.12%.

[0028] 2. A Ni-CaSiO3 catalyst was prepared by a hydrothermal method. This preparation method is simple, easy to operate, and low in cost. It exhibits strong stability and resistance to carbon deposition in methane dry reforming reactions and is suitable for industrial production.

[0029] Figure 1 The graphs show the catalytic performance test results of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6.

[0030] Figure 2 The XRD patterns are those of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6.

[0031] Figure 3 The H2-TPR spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6 are shown.

[0032] Figure 4 XPS spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6.

[0033] Figure 5The TG spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6 are shown. Detailed Implementation

[0034] The present invention will be further illustrated by some implementation examples below, but these examples do not limit the scope of the invention.

[0035] Example 1

[0036] The steps for preparing the catalyst for dry reforming of methane are as follows:

[0037] 0.991 g of Ni(NO3)2·6H2O (the mass fraction of the active component Ni is 10 wt%) was weighed and added to 30 mL of deionized water and stirred until completely dissolved. Then, 20 mL of tetraethyl orthosilicate was added dropwise, and the mixture was stirred at room temperature for 1 h. After that, the beaker was placed in an 80 ℃ constant temperature magnetic water bath and stirred to dry until the liquid was completely evaporated. Then, it was transferred to a 110 ℃ oven and dried overnight to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 700 ℃ for 4 h. The calcined powder was then pressed into tablets and crushed to 20-40 mesh using a tablet press at a pressure of 20 MPa to obtain the Ni-SiO2 catalyst. The catalyst composition of Example 1 is shown in Table 1.

[0038] Catalyst evaluation

[0039] The stability of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube and controlled by a temperature programmable controller. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every 0.5 h. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 1 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0040] Example 2

[0041] Ni-CaO catalyst was prepared using the sol-gel method. 0.991 g of Ni(NO3)2·6H2O (with an active component Ni mass fraction of 10 wt%) and 5.781 g of Ca(NO3)2·6H2O were weighed and dissolved in 30 mL of deionized water. An appropriate amount of citric acid was added, and the mixture was then placed in an 80 ℃ constant-temperature magnetic water bath and stirred to form a wet gel. The gel was then dried in a 110 ℃ oven until bubbling occurred, and subsequently ground into a fine powder to obtain the precursor. The obtained precursor was calcined in a muffle furnace at 700 ℃ for 4 h. The calcined powder was then pressed into tablets at a pressure of 20 MPa to a mesh size of 20-40 to obtain the Ni-CaO catalyst. The catalyst composition of Example 2 is shown in Table 1.

[0042] Catalyst evaluation

[0043] Following the evaluation method of Implementation Case 1, the specific procedures are as follows: The catalytic performance of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube, and a programmed temperature control was used to control the reaction temperature. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every half hour. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 1 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0044] Example 3

[0045] 100 mL of deionized water and 100 mL of anhydrous ethanol were mixed thoroughly, and 25 mL of tetraethyl orthosilicate and ammonia were added dropwise. After stirring thoroughly, the mixture was allowed to stand for a period of time to obtain a layered SiO2 precipitate. The precipitate was filtered, washed, dried, and calcined at 550 °C to prepare a SiO2 support. A Ni / CaO-SiO2 catalyst was prepared using a stepwise impregnation method. 0.642 g of calcium nitrate tetrahydrate was dissolved in 30 mL of deionized water, and 1.6 g of the prepared SiO2 support was added. The mixture was impregnated at room temperature for 45 min, transferred to an 80 °C constant temperature water bath for drying, dried overnight at 110 °C, and calcined at 700 °C for 4 h to obtain the CaO-SiO2 support. A certain amount of nickel nitrate hexahydrate (active component Ni mass fraction of 10 wt%) was weighed and dissolved in 30 mL of deionized water. Then, 1.8 g of CaO-SiO2 support was weighed, stirred and mixed, and impregnated at room temperature for 45 min. The mixture was then transferred to an 80 ℃ constant temperature water bath for drying, and dried overnight at 110 ℃. Finally, it was calcined in a muffle furnace at 700 ℃ for 4 h. The calcined powder was then pressed into tablets and crushed to 20-40 mesh using a tablet press under a pressure of 20 MPa to obtain the Ni / CaO-SiO2 catalyst. The catalyst composition of Example 3 is shown in Table 1.

[0046] Catalyst evaluation

[0047] Following the evaluation method of Implementation Case 1, the specific procedures are as follows: The catalytic performance of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube, and the reaction temperature was controlled using a programmed temperature controller. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every half hour. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 2 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0048] Example 4

[0049] 100 mL of deionized water and 100 mL of anhydrous ethanol were mixed evenly, and 25 mL of tetraethyl orthosilicate and ammonia were added dropwise. After thorough stirring, the mixture was allowed to stand for a period of time to obtain a layered SiO2 precipitate. The precipitate was filtered, washed, dried, and calcined at 550 °C to prepare a SiO2 support. A Ni-CaO / SiO2 catalyst was prepared using a co-impregnation method. 0.991 g of nickel nitrate hexahydrate (active component Ni mass fraction of 10 wt%) and 0.642 g of calcium nitrate tetrahydrate were weighed and dissolved in 30 mL of deionized water. Then, 1.6 g of SiO2 support was weighed, stirred, and impregnated at room temperature for 45 min. The mixture was then transferred to an 80 °C constant temperature water bath for drying, dried overnight at 110 °C, and calcined in a muffle furnace at 700 °C for 4 h. The calcined powder was then pressed into tablets at 20 MPa and crushed to 20-40 mesh to obtain the Ni-CaO / SiO2 catalyst. The catalyst composition of Example 4 is shown in Table 1.

[0050] Catalyst evaluation

[0051] Following the evaluation method of Implementation Case 1, the specific procedures are as follows: The catalytic performance of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube, and the reaction temperature was controlled using a programmed temperature controller. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every half hour. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 2 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0052] Example 5

[0053] The CaSiO3 support was prepared by hydrothermal method. A certain amount of CTAB was weighed and added to 30 ml of deionized water, followed by 0.27 g of NaOH solid. The mixture was dissolved by stirring in a 60 ℃ constant temperature water bath. Then, a pre-prepared calcium nitrate tetrahydrate aqueous solution was added dropwise, and the mixture was stirred for 30 min. 5.76 mL of tetraethyl orthosilicate solution was added, and the mixture was stirred thoroughly at room temperature for 1 h. The mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and hydrothermally reacted at 110 ℃ for 48 h. After cooling to room temperature, the mixture was centrifuged, washed three times with deionized water, dried overnight at 110 ℃, and then calcined in a muffle furnace at 700 ℃ for 4 h. The Ni / CaSiO3 catalyst was prepared by impregnation. 0.991 g of nickel nitrate hexahydrate (with a Ni mass fraction of 10 wt%) was dissolved in 30 mL of deionized water. Then, 1.8 g of CaSiO3 support was weighed, stirred, and impregnated at room temperature for 45 min. The mixture was then transferred to an 80 ℃ constant temperature water bath for drying, followed by overnight drying at 110 ℃. Finally, the powder was calcined in a muffle furnace at 700 ℃ for 4 h. The calcined powder was then pressed into tablets to a density of 20-40 mesh using a tablet press at 20 MPa, yielding the Ni / CaSiO3 catalyst. The catalyst composition of Example 5 is shown in Table 1.

[0054] Catalyst evaluation

[0055] Following the evaluation method of Implementation Case 1, the specific procedures are as follows: The catalytic performance of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube, and the reaction temperature was controlled using a programmed temperature controller. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every 0.5 h. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 2 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0056] Example 6

[0057] Ni-CaSiO3 catalyst was prepared by hydrothermal method. A certain amount of CTAB was weighed and added to 30 mL of deionized water, followed by 0.27 g of NaOH solid. The mixture was dissolved by stirring in a 60 ℃ constant temperature water bath. A pre-prepared mixed aqueous solution of nickel nitrate hexahydrate and calcium nitrate tetrahydrate was then added dropwise, followed by 5.76 mL of tetraethyl orthosilicate solution. The mixture was stirred thoroughly for 1 h, then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE). The reaction was carried out hydrothermally at 110 ℃ for 48 h. After cooling to room temperature, the mixture was centrifuged, washed three times with deionized water, dried overnight in a 110 ℃ oven, and calcined in a muffle furnace at 700 ℃ for 4 h. The calcined powder was then pressed into tablets to 20-40 mesh using a tablet press at a pressure of 20 MPa, thus obtaining the Ni-CaSiO3 catalyst. The catalyst composition of Example 6 is shown in Table 1.

[0058] Catalyst evaluation

[0059] Following the evaluation method of Implementation Case 1, the specific procedures are as follows: The catalytic performance of the catalyst was evaluated in a self-made continuous flow fixed-bed reactor. The reaction tube was a quartz tube with an inner diameter of 6 mm and a length of 33 cm. The reaction temperature was measured by a thermocouple placed in the middle of the reaction tube, and the reaction temperature was controlled using a programmed temperature controller. The gas flow rate was controlled by a mass flow meter, and the space velocity was 36000 mL∙h. -1 • The reactant gases were 24.2 mL / min CH4 and 26.4 mL / min CO2. The catalyst dosage was 0.1 g, the reaction temperature was 700 ℃, and samples were taken every half hour. The gas composition of the reactants and products was analyzed using a profile gas chromatograph (SC-8000B) to calculate the conversion rates of CH4 and CO2. The conversion curves of the catalyst to CH4 and CO2 at different time points are shown in the figure. Figure 1 As shown in Table 1, the initial conversion rates of CH4 and CO2 are shown in Table 1.

[0060] Table 1 Catalyst composition, CH4 and CO2 conversion rates, and CO yield of specific embodiments: 1 <![CDATA[Ni-SiO2]]> 10 - 90 roasting One-pot method 62.48 62.77 63.07 2 Ni-CaO 10 90 - roasting Sol-gel method 59.95 67.23 61.54 3 <![CDATA[Ni / CaO-SiO2]]> 10 10 80 roasting Impregnation method 69.31 71.77 72.89 4 <![CDATA[Ni-CaO / SiO2]]> 10 10 80 roasting Impregnation method 70.10 62.50 56.54 5 <![CDATA[Ni / CaSiO3]]> 10 10 80 roasting Impregnation method 65.33 71.69 70.98 6 <![CDATA[Ni-CaSiO3]]> 10 10 80 roasting hydrothermal method 79.18 80.41 77.53

[0061] Table 2. CH4 deactivation rate and carbon deposition after catalyst reaction in Examples 1, 2, 3, 4, 5, and 6: 1 <![CDATA[Ni-SiO2]]> 20 h 25.72 35.21 2 Ni-CaO 20 h 14.93 5.96 3 <![CDATA[Ni / CaO-SiO2]]> 20 h 8.9 0.63 4 <![CDATA[Ni-CaO / SiO2]]> 20 h 48.96 0.51 5 <![CDATA[Ni / CaSiO3]]> 20 h 4.29 0.44 6 <![CDATA[Ni-CaSiO3]]> 20 h 7.2 0.12

[0062] XRD characterization

[0063] The XRD patterns of Examples 1, 2, 3, 4, 5, and 6 are as follows: Figure 2As shown, characteristic NiO diffraction peaks appear at 2θ = 37.2°, 43.3°, 62.9°, 75.4°, and 79.4° [PDF#75-0917]. Compared with conventional Ni-SiO2 catalysts, the intensity of characteristic diffraction peaks of Ni-based catalysts doped with Ca is significantly reduced, indicating that Ca doping can improve the dispersion of Ni particles within the catalyst to a certain extent, thereby enhancing the catalyst activity. It is also noteworthy that the Ni-CaSiO3 catalyst prepared by the hydrothermal method exhibits the lowest diffraction peaks, indicating that its Ni particle size is the smallest. This catalyst demonstrates the best reforming activity, and the well-dispersed Ni is less prone to agglomeration.

[0064] The H2-TPR spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6 are shown below. Figure 3 As shown, compared to the undoped base catalyst, the reduction peak of the catalyst doped with Ca in the silicate framework is observed at a higher temperature, indicating a stronger interaction between the active metal and the support. This suggests that the addition of Ca promotes the bonding between the active metal and the support, which significantly reduces the migration and aggregation of the active metal at high temperatures, thereby greatly improving the stability of the catalyst.

[0065] XPS spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6 are shown below. Figure 4 As shown, Example 6 exhibits a stronger binding energy than Examples 1, 2, 3, 4, and 5, indicating a stronger interaction between the active metal and the support in the catalyst. This is consistent with the results of H2-TPR, where hydrothermal anchoring of the metal enables the catalyst to acquire stronger metal-support interactions, thereby improving the catalyst's resistance to sintering and enhancing its stability.

[0066] The TG spectra of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6 are as follows: Figure 5 As shown, compared with the undoped base catalyst, the amount of carbon deposited in the catalyst after Ca doping into the silicate framework is significantly reduced, indicating that the introduction of Ca can improve the catalyst's resistance to carbon deposition. Among them, the catalyst prepared by the hydrothermal method has the least amount of carbon deposited after the reaction, indicating that this catalyst has the strongest resistance to carbon deposition.

Claims

1. A method for preparing and applying a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition, characterized in that, The method includes the following steps: (1) Weigh the active components according to the stoichiometric ratio (with the total mass of the support and active component Ni being 100%, the mass percentage of active component Ni in the catalyst being 10%, the mass percentage of the promoter being 10%, and the mass percentage of the support being 80%). Among these, nickel nitrate hexahydrate (Ni(NO3)2·6H2O) is the source of the active component Ni, and tetraethyl orthosilicate (C8H2O) is the source of the active component Ni. 20 Ni(NO3)2·6H2O was used as the Si source and calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) was used as the Ca source. Ni(NO3)2·6H2O and Ca(NO3)2·4H2O were added to deionized water and stirred until completely dissolved to obtain a transparent solution. (2) Weigh a certain amount of CTAB and add it to deionized water, then add a certain amount of NaOH solid, and place it on a 60 ℃ constant temperature water bath and stir until the solution is clear; (3) Add the metal salt solution in (1) dropwise to the clear solution in (2) using a dropper, and stir the mixture in a 60 ℃ constant temperature water bath for 30 min. (4) Weigh the C8H obtained in step (1) 20 O4Si was added to the green slurry obtained in step (3); the beaker was sealed with plastic wrap and then transferred to room temperature and stirred for 1 h. (5) The green suspension obtained in step (4) was transferred into a high-pressure reactor lined with polytetrafluoroethylene and placed in a constant temperature drying oven at 110 °C for 48 h. (6) After cooling (5) to room temperature, take it out, pour the suspension into a centrifuge tube, wash it repeatedly with deionized water three times to obtain a green precipitate; (7) Place the green precipitate obtained in step (6) in a constant temperature drying oven and dry it overnight to obtain green powder; (8) Place the powder obtained in step (7) in a muffle furnace, calcine it, cool it naturally to room temperature, press it into tablets, and grind it into a catalyst with a mesh size of 20-40 to obtain the methane dry reforming catalyst.

2. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition according to claim 1, characterized in that, The total mass of the support and active component Ni is 100%, the mass percentage of active component Ni in the catalyst is 10%, the mass percentage of the additive is 10%, and the total mass of the support is 80%.

3. A method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition according to any one of claims 1-2, characterized in that, The carrier uses C8H 20 O4Si is used as raw material.

4. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition as described in any one of claims 1-3, characterized in that, With the catalyst mass being 100% and the active component Ni mass percentage being 10%, the catalyst mass is 10%.

5. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition as described in any one of claims 1-4, characterized in that, With the carrier mass as 100%, the mass percentage of the auxiliary agent Ca is 10%.

6. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition as described in any one of claims 1-5, characterized in that, It was prepared by hydrothermal method.

7. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition as described in any one of claims 1-6, characterized in that, The stirring temperature is 60 ℃; the drying temperature is 110 ℃; and the drying time is 11-13 h.

8. The method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition according to claims 1-7, characterized in that, The activation method is calcination.

9. A method for preparing a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition according to any one of claims 1-8, characterized in that, The roasting temperature is 700 ℃; the roasting time is 4 h.

10. The application of a methane dry reforming catalyst with strong stability and strong resistance to carbon deposition as described in any one of claims 1-9 in carbon dioxide conversion.

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