CN107376919B - Promoting CO2Catalyst for activation and dissociation and preparation method and application thereof - Google Patents

Abstract

The invention discloses a method for promoting CO₂An activating dissociation catalyst and a preparation method and application thereof. The catalyst is characterized in that an active component metal Ni and an auxiliary agent MgO are loaded on an oxide carrier, the mass ratio of the oxide carrier to the metal Ni to the auxiliary agent MgO is 1: 0.01-0.15: 0.0001-0.02, and the oxide carrier is one of silicon dioxide, aluminum oxide, titanium dioxide, lanthanum oxide and zirconium oxide. The invention prepares the precursors with different Ni particle sizes by a step-by-step impregnation method, then loads MgO on the Ni particles with different sizes, adjusts the electron supply capacity of MgO by regulating the Ni particle size, improves the electron density of Ni, and promotes CO₂Activated dissociation of (3). The preparation method has the advantages of simple process, convenient operation, easily controlled synthesis conditions and easy industrialization, and the obtained catalyst has high catalytic activity and anti-carbon deposition performance.

Description

A catalyst for promoting the activation and dissociation of CO2 and its preparation method and application

technical field

The invention relates to a catalyst for promoting the activation and dissociation of _CO2 , a preparation method and application thereof, and belongs to the technical field of catalyst preparation.

Background technique

Methane carbon dioxide reforming can simultaneously convert two greenhouse gases, CO ₂ and CH ₄ into syngas (H ₂ , CO), which has potential commercial value and is of great significance for carbon dioxide emission reduction and mitigation of the greenhouse effect. However, due to the lack of catalysts with good catalytic activity and stability, its industrial application is limited. Existing studies have shown that noble metal catalysts have good catalytic performance and stability, but they are not suitable for industrial production due to their high price. Among non-metallic catalysts, Ni-based catalysts have high catalytic activity and low price, so they have attracted much attention, but the surface of Ni-based catalysts is prone to carbon deposition. Therefore, how to design and prepare Ni-based catalysts with high catalytic activity and high stability is the key to the industrialization of methane and carbon dioxide reforming.

Through theoretical analysis of the activation process of CO ₂ and CH ₄ two small molecules, the reaction mechanism of methane and carbon dioxide reforming and the process of carbon deposition, it can be seen that the carbon deposition on the surface of Ni-based catalyst is due to the carbon deposition in the reaction process. The imbalance in the generation rates of species and O species results in the activation of surface O species from the activated dissociation of _CO and the C species from the activated dissociation of CH _. To solve the problem of carbon deposition, it is necessary to balance the generation rates of C species and O species on a macro level, and on a micro level, it is necessary to balance the activation ability of the catalyst for CH ₄ with the activation and dissociation ability of CO _2. Among them, the promotion of the activity of CO ₂ Chemical dissociation is the key to improve the anti-coking performance of catalysts. The activation and dissociation of _CO2 is dominated by electron transfer, and promoting the activation and dissociation of _CO2 requires increasing the electron density of Ni. MgO has a certain electron donating ability. When added as an auxiliary agent in Ni-based catalysts, it can increase the electron density of Ni and promote the activation and dissociation of _CO2 , thereby improving the anti-carbon performance of Ni-based catalysts.

SUMMARY OF THE INVENTION

The present invention aims to provide a catalyst for promoting the activation and dissociation of CO ₂ . Using Ni as an active component and MgO as an auxiliary agent, precursors of different Ni particle sizes are prepared by a step-by-step impregnation method, and then Ni particles of different sizes are prepared in different sizes of Ni particles. It is expected that the electron-donating ability of MgO can be adjusted by adjusting the size of Ni particles, so as to achieve the purpose of promoting the activation balance of CO ₂ and CH ₄ by the catalyst, and solve the problem of carbon deposition of Ni-based catalysts from the perspective of molecular activation. The present invention also provides the preparation method and application of the catalyst for promoting the activation and dissociation of CO ₂ .

The invention provides a catalyst for promoting the activation and dissociation of CO ₂ . The catalyst is to support active component metal Ni and auxiliary agent MgO on an oxide carrier, and the mass ratio of the oxide carrier to metal Ni and auxiliary agent MgO is 1: 0.01~0.15:0.0001~0.02; the oxide carrier is one of silicon dioxide, aluminum oxide, titanium dioxide, lanthanum oxide, and zirconium oxide.

In the above catalyst, the mass ratio of the oxide carrier to the metal Ni and the auxiliary agent MgO is 1:0.03-0.05:0.005-0.008.

The present invention provides the above-mentioned preparation method of the catalyst for promoting _CO activation and dissociation, comprising the following steps:

Step 1: Weigh the precursor salt of nickel and dissolve it in deionized water to form mixed solution A, and the concentration of nickel ions in solution A is 0.5~3mol/L;

Step 2: Immerse the oxide carrier in solution A, and the mass ratio of the oxide carrier to the nickel ion is 1:0.01~0.15; ultrasonicate for 0.5~2h at room temperature, and vacuum dry the obtained viscous material at 50~150°C 12~36h, calcination in air at 500~800℃ for 2~6h to obtain the catalyst precursor.

Step 3: Weigh the precursor salt of magnesium and dissolve it in deionized water to form mixed solution B, and the concentration of magnesium ions in solution B is 0.01 to 0.5 mol/L;

Step 4: Immerse the catalyst precursor obtained in step 2 in solution B, and the mass ratio of oxide carrier and auxiliary MgO is 1:0.0001~0.02; ultrasonically at room temperature for 0.5~2h, the obtained viscous substance is subjected to Vacuum drying at 50~150°C for 12~36h, calcination in air at 600~900°C for 2~10h, to obtain a catalyst that promotes the activation and dissociation of _CO2 .

In the above-mentioned method step 1, the precursor salt of the nickel is one of nickel nitrate, nickel acetate, nickel sulfate, nickel chloride, and ethylenediamine nickel (prepared by nickel nitrate and ethylenediamine in a molar ratio of 1:3). kind. Further, the precursor salt of nickel is preferably ethylenediamine nickel.

In step 3 of the above method, the magnesium precursor salt is one of magnesium nitrate, magnesium acetate, magnesium sulfate, and magnesium chloride.

A preferred preparation method is provided, comprising the following steps:

Step 1: Weigh the precursor salt of nickel and dissolve it in deionized water to form mixed solution A, and the concentration of nickel ions in solution A is 0.8~1.5mol/L;

Step 2: Immerse the oxide carrier in the solution A, the mass ratio of the oxide carrier to the nickel ion is 1:0.03~0.05; ultrasonicate for 0.5~2h at room temperature, and vacuum dry the obtained viscous material at 80~100°C 15~24h, calcination in air at 600~700℃ for 3~5h to obtain catalyst precursor;

Step 3: Weigh the precursor salt of magnesium and dissolve it in deionized water to make mixed solution B, and the concentration of magnesium ions in solution B is 0.1~0.2mol/L;

Step 4: Immerse the catalyst precursor obtained in step 2 in solution B, and the mass ratio of oxide carrier and auxiliary MgO is 1:0.005~0.008; ultrasonically at room temperature for 0.5~2h, the obtained viscous substance is subjected to Vacuum drying at 80~100°C for 15~24h, and calcination in air at 800~900°C for 4~6h to obtain a catalyst that promotes the activation and dissociation of _CO2 .

The present invention provides the application of the above catalyst for promoting CO ₂ activation dissociation in the methane carbon dioxide reforming reaction.

In the described application, the catalyst needs to be reduced with 10% H ₂ /Ar mixed gas for 30 min before use. The suitable reaction conditions are that the volume ratio of the raw material gas methane and carbon dioxide is 1:1, the reaction temperature is 750 ° C, and the normal pressure is used. , the raw material space velocity is 36000h ^-1 . The catalyst is used in the methane carbon dioxide reforming reaction, and the reaction activity is close to the equilibrium conversion rate, the life is long, and the H ₂ /CO ratio of the product is close to 1.

The catalyst is reduced before use for the purpose of: the prepared catalyst active component Ni exists in the form of NiO, which needs to be reduced to a metallic state before use.

For the impregnation method, when different types of metal salt solutions of the same active component are used, due to the different reaction mechanisms between the complexes in the metal salts and the ligands generated during the impregnation of the oxide support, the resulting The distribution of active components in the prepared catalysts varies. Using different organic/inorganic Ni salt solutions as immersion solution, Ni salt anions can form complexes or hydrogen bonds with hydroxyl groups on the surface of oxide supports. The binding form and stability of the anions of different Ni salts to the surface of the oxide support are different, which affects the dispersion state and reduction degree of Ni, resulting in differences in catalyst size and catalytic performance.

Beneficial effects of the present invention:

The invention provides a catalyst for promoting the activation and dissociation of CO ₂ , which solves the problem that the generation rates of C species and O species do not match in the reaction process. The preparation method provided by the invention has the advantages of simple process, convenient operation, easy control of synthesis conditions and easy industrialization, and the prepared catalyst has high catalytic activity and anti-coking performance.

Description of drawings

FIG. 1 is the XRD pattern of the catalyst for promoting the activation and dissociation of CO ₂ prepared in Example 1 of the present invention and the catalyst for promoting the activation and dissociation of CO ₂ prepared in Comparative Examples 1 and 2 after reduction.

FIG. 2 is the H ₂ -TPR diagram of the CO ₂ activation dissociation catalyst prepared in Example 1 of the present invention and the CO ₂ activation dissociation catalyst prepared in Comparative Examples 1 and 2. FIG.

3 is the Ni 2p XPS spectrum of the catalyst for promoting CO ₂ activation and dissociation prepared in Example 1 of the present invention and the catalyst for promoting CO ₂ activation and dissociation prepared in Comparative Examples 1 and 2.

Detailed ways

The present invention is further illustrated by the following examples, but is not limited to the following examples.

Example 1:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 1.56g of ethylenediamine nickel and dissolve it in 6mL of deionized water to make mixed solution A;

(2) Immerse 10 g of silica in solution A, sonicate for 0.5 h at room temperature, vacuum dry the obtained viscous material at 90 °C for 24 h, and calcine it in air at 600 °C for 3 h to obtain a catalyst precursor.

(3) Weigh 0.4g of magnesium nitrate and dissolve it in 8mL of deionized water to prepare mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, ultrasonicated for 0.5 h at room temperature, the obtained viscous material was vacuum-dried at 90 °C for 24 h, and calcined at 800 °C in air for 4 h to obtain a promoted CO ₂ The dissociated catalyst was activated, and the Ni crystallite size in the catalyst was 8.83 nm.

Example 2:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 3g of nickel acetate and dissolve it in 12mL of deionized water to make mixed solution A;

(2) Immerse 10 g of aluminum oxide in solution A, sonicate for 1 h at room temperature, vacuum dry the obtained viscous material at 100 °C for 24 h, and calcine it in air at 800 °C for 2 h to obtain a catalyst precursor.

(3) Weigh 0.08g of magnesium nitrate and dissolve it in 10mL of deionized water to make mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, sonicated for 1 h at room temperature, the obtained viscous material was vacuum-dried at 100 °C for 24 h, and calcined at 800 °C in air for 4 h to obtain the promotion of CO ₂ activity. The dissociated catalyst, the Ni crystallite size in this catalyst is 12.38 nm.

Example 3:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 1.56g of nickel nitrate and dissolve it in 6mL of deionized water to make mixed solution A;

(2) Immerse 10 g of silica in solution A, sonicate for 1.5 h at room temperature, vacuum dry the obtained viscous material at 60 °C for 36 h, and calcine it in air at 600 °C for 4 h to obtain a catalyst precursor.

(3) Weigh 0.05g of magnesium nitrate and dissolve it in 6mL of deionized water to make mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, ultrasonicated for 1.5 h at room temperature, the obtained viscous material was vacuum-dried at 60 °C for 36 h, and calcined at 900 °C in air for 2 h to obtain a promoted CO ₂ The dissociated catalyst was activated and the Ni crystallite size was 15.49 nm.

Example 4:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 1.56g of ethylenediamine nickel and dissolve it in 6mL of deionized water to make mixed solution A;

(2) Immerse 10 g of aluminum oxide in solution A, sonicate for 0.5 h at room temperature, vacuum dry the obtained viscous material at 120 °C for 15 h, and calcine it in air at 500 °C for 6 h to obtain a catalyst precursor.

(3) Weigh 0.9g of magnesium sulfate and dissolve it in 15mL of deionized water to make mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, ultrasonicated for 0.5 h at room temperature, the obtained viscous material was vacuum-dried at 120 °C for 15 h, and calcined at 700 °C in air for 10 h to obtain the promoted CO ₂ The dissociated catalyst was activated and the Ni crystallite size was 8.83 nm. Example 5:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 1.0g of nickel sulfate and dissolve it in 6mL of deionized water to make mixed solution A;

(2) Immerse 10 g of titanium dioxide in solution A, sonicate for 2 h at room temperature, vacuum dry the obtained viscous material at 80 °C for 30 h, and calcine it in air at 800 °C for 2 h to obtain a catalyst precursor.

(3) Weigh 0.1 g of magnesium chloride and dissolve it in 4.5 mL of deionized water to make mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, ultrasonicated for 2 h at room temperature, the obtained viscous material was vacuum-dried at 80 °C for 30 h, and calcined at 600 °C in air for 10 h to obtain the promotion of CO ₂ activity. The dissociated catalyst has a Ni crystallite size of 16.82 nm.

Example 6:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 5g of ethylenediamine nickel and dissolve it in 10mL of deionized water to make mixed solution A;

(2) Immerse 10 g of zirconium dioxide in solution A, sonicate for 0.5 h at room temperature, vacuum dry the obtained viscous material at 140 °C for 12 h, and calcine it in air at 600 °C for 5 h to obtain a catalyst precursor.

(3) Weigh 0.25g of magnesium nitrate and dissolve it in 5mL of deionized water to make mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, sonicated for 0.5 h at room temperature, the obtained viscous material was vacuum-dried at 140 °C for 12 h, and calcined at 800 °C in air for 8 h to obtain promoted CO ₂ The dissociated catalyst was activated, and the Ni crystallite size in the catalyst was 14.87 nm.

Example 7:

Adopting the method of the present invention to prepare a catalyst for promoting the activation and dissociation of CO ₂ comprises the following steps:

(1) Weigh 4g of nickel chloride and dissolve it in 6mL of deionized water to make mixed solution A;

(2) Immerse 10 g of lanthanum oxide in solution A, sonicate for 1.5 h at room temperature, vacuum dry the obtained viscous material at 90 °C for 20 h, and calcine it in air at 700 °C for 5 h to obtain a catalyst precursor.

(3) Weigh 0.6g of magnesium acetate and dissolve it in 8mL of deionized water to prepare mixed solution B;

(4) The catalyst precursor obtained in step 2 was immersed in solution B, ultrasonicated for 1.5 h at room temperature, the obtained viscous material was vacuum-dried at 90 °C for 20 h, and calcined at 900 °C in air for 3 h to obtain the promotion of CO ₂ The dissociated catalyst was activated and the Ni crystallite size was 21.88 nm.

Comparative Example 1:

A catalyst for promoting the activation and dissociation of CO ₂ is prepared by a co-impregnation method, including the following steps:

(1) Weigh 1.56g of ethylenediamine nickel and 0.4g of magnesium nitrate and dissolve them in 14mL of deionized water to make mixed solution A;

(2) Add 10 g of silica to solution A, and stir to dryness at room temperature;

(3) The material obtained in step 2 was dried in a drying oven at 120 °C overnight, and calcined at 800 °C for 4 h to obtain a catalyst that promotes the activation and dissociation of CO ₂ . The Ni crystallite size in the catalyst is 10.47 nm. .

Comparative Example 2

A catalyst for promoting the activation and dissociation of CO ₂ is prepared by a co-precipitation method, including the following steps:

(1) Dissolve 1.56g of ethylenediamine nickel, 0.4g of magnesium nitrate and 37mL of ethyl orthosilicate in a solution of 14mL of deionized water and 20mL of ethanol to prepare mixed solution A;

(2) Dissolve 10 g of sodium hydroxide in 150 mL of deionized water to obtain solution B;

(3) Dissolve 5.512 g of sodium carbonate in 200 mL of deionized water to obtain solution C;

(4) Pour solution A and solution B into two constant pressure dropping funnels respectively, pour solution C into the three-necked flask, drop solution A into the three-necked flask at 60°C, and use solution B to adjust the solution during the process. pH, to maintain pH around 10;

(5) Aging the precipitate obtained in step 4 at 60°C for 18h, and then washing with suction filtration until the filtrate is neutral;

(6) The material obtained in step 5 was dried in a drying oven at 120 °C overnight, and calcined at 800 °C for 4 h to obtain a catalyst that promotes the activation and dissociation of CO ₂ . The Ni crystallite size in the catalyst is 15.91 nm. .

Data detection results:

FIG. 1 shows the XRD patterns of the catalyst for promoting the activation and dissociation of CO ₂ prepared in Example 1 of the present invention and the catalyst for promoting the activation and dissociation of CO ₂ prepared in Comparative Examples 1 and 2 after reduction. According to the standard spectra of Ni and MgO, the diffraction peaks at 2θ=44.5°, 51.8° and 76.3° correspond to Ni(111), Ni(200), Ni(220), and are located at 2θ=42.9°, 62.3° and 74.6°, respectively. The diffraction peaks of ° correspond to the characteristic diffraction peaks of MgO (200), MgO (220) and MgO (311), respectively. Characteristic peaks of Ni(111) and Ni(200) were observed in all reduced catalyst XRD patterns. The bulge around 2θ=22° is attributed to amorphous SiO ₂ . Since the loading of MgO is only 0.4 wt.%, no characteristic peaks of MgO are observed, and no characteristic peaks of NiO-MgO solid solution are observed at 2θ=75° and 79°.

Table 1 is a comparison of the metal surface area, particle size and dispersibility of the catalyst for promoting CO ₂ activation and dissociation prepared in Example 1 of the present invention, and the catalyst for promoting CO ₂ activation and dissociation prepared in Comparative Example 1 and Comparative Example 2.

Table 1 Comparison of metal properties of catalysts

It can be seen from Table 1 that the catalysts obtained by different preparation methods have different metal dispersions and different Ni particle sizes (Table 1). The catalyst prepared in Example 1 has the highest metal dispersion and the smallest Ni particle size (8.83 nm). This is because in different preparation methods, the force of ethylenediamine nickel to form hydrogen bonds with hydroxyl groups on the surface of _SiO2 is different, which eventually leads to the difference in Ni particle size and dispersion.

FIG. 2 shows the TPR diagrams of the catalyst for promoting the activation and dissociation of CO ₂ prepared in Example 1 of the present invention, and the catalyst for promoting the activation and dissociation of CO ₂ prepared in Comparative Examples 1 and 2. It can be seen from the figure that the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention all show the reduction peaks of NiO in the surface layer of NiO-MgO solid solution and the subsurface layer, which proves that in the catalysts with different Ni particle sizes, all forms of NiO-MgO solid solution. NiO-MgO solid solution structure.

FIG. 3 shows the Ni 2p XPS diagram of the catalyst for promoting CO ₂ activation and dissociation prepared in Example 1 of the present invention and the catalyst for promoting CO ₂ activation and dissociation prepared in Comparative Examples 1 and 2. According to literature reports, the XPS peak of Ni ⁰ is at ^852.6 eV, and the XPS peak of Ni ²⁺ is at 855.5 eV, and the lower the XPS binding energy, the higher the electron density of the corresponding transition metal, that is, the lower the valence state. The XPS binding energies of Ni ⁰ catalysts in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are 851.99 eV, 852.10 eV and 852.48 eV, respectively. Obviously, the XPS peaks of each catalyst Ni ⁰ are shifted to the direction of low binding energy by 0.12– 0.61 eV, indicating that there is electron transfer between MgO and Ni. Combined with the data in Table 1, it can be found that the electron donating ability of MgO in the catalyst increases with the decrease of Ni particle size, and the electron density of Ni ⁰ gradually increases. The Ni particle size has a direct impact on the electron donating ability of MgO. The smaller the Ni particle size, the stronger the electron donating ability of MgO.

Example 8: Activity Evaluation Experiment

The catalyst for promoting CO ₂ activation dissociation prepared in Example 1 was used in the methane carbon dioxide reforming reaction, and the catalytic effect was compared with the catalytic activity of the catalyst prepared in Comparative Example 1 and Comparative Example 2.

The specific experiment is as follows: 0.2g catalyst is loaded into a fixed bed reactor, the reaction temperature is 750°C, 0.1MPa, the flow rate of CH ₄ and CO ₂ is 60mL/min, and the space velocity is 36000h ^-1 . Before the reaction, the catalyst was reduced with 60 mL/min (10% H ₂ /Ar) gas mixture for 30 min. Collected through a gas sampling bag and analyzed off-line in gas chromatography. The chromatographic conditions were: argon as carrier gas, vaporizer temperature of 120°C, column furnace temperature of 70°C, thermal conductivity temperature of 70°C, and current of 50 mA. At the same time, the ratio of reactants in the inlet gas and the ratio of different products in the outlet gas, and the flow rate of the reactor inlet gas and the reactor outlet gas were measured, and finally the conversion rate of the reactants and the selectivity of the products were calculated.

Example 9: Life Evaluation Experiment

According to the steps of Example 8, the time of the methane carbon dioxide reforming reaction was extended, and the life evaluation experiment was carried out.

Table 2 is a comparison of the activity and life evaluation results of the catalyst for promoting CO ₂ activation and dissociation prepared in Example 1 of the present invention, and the catalyst for promoting CO ₂ activation and dissociation prepared in Comparative Examples 1 and 2. It can be seen that the catalyst activity and stability prepared by the embodiment of the present invention ₁ are all good, and the conversion rate of CH in 8h is kept at 83.6%, and the conversion rate of _CO is kept at 89.9%, which is close to the thermodynamic equilibrium of 750 ° C. The conversion rate (CH ₄ is 84%, CO ₂ is 91%), after the reaction for 8h, the catalyst carbon deposition amount is 0.12wt%; while the activity and stability of the catalysts in Comparative Examples 1 and 2 are significantly lower than those in the embodiment of the present invention 1 catalyst. After 8 h of reaction, the carbon deposits of the bimetallic catalysts prepared in Comparative Example 1 and Comparative Example 2 were 1.7 wt% and 2.8 wt%, respectively. Combined with the previous structural analysis of the catalyst, it can be seen that with the reduction of the Ni particle size, the electron donating ability of MgO increases, and the electron density of Ni increases, which enhances the activation and dissociation ability of the catalyst for CO ₂ . All these factors contribute to the high catalytic activity and stability of the catalyst of Example 1 of the present invention.

In order to investigate the life of the catalyst for promoting CO ₂ activation and dissociation prepared by the present invention, the conversion rates of CH ₄ and CO ₂ after the reaction of 8h, 50h and 200h were compared. The prepared catalyst for promoting _{CO 2} activation and dissociation still maintains a high conversion rate of CH ₄ and CO ₂ . The amount of carbon deposits on the dissociation catalyst for 8h (Table 2). It can be seen that the catalyst for promoting CO ₂ activation and dissociation prepared by the method of the present invention not only has high catalytic activity, but also has good anti-carbon deposition performance and long catalyst life.

Table 2 Reaction performance of the catalyst for promoting _CO activation and dissociation prepared by the present invention

Claims (6)

1. Promoting CO₂The catalyst for activation and dissociation is prepared by loading active component metal Ni and auxiliary agent MgO on an oxide carrier, wherein the mass ratio of the oxide carrier to the metal Ni to the auxiliary agent MgO is 1: 0.03-0.05: 0.005-0.008; its special featureCharacterized by being prepared by the following steps:

step one, weighing nickel precursor salt, dissolving the nickel precursor salt in deionized water to prepare a mixed solution A, wherein the concentration of nickel ions in the solution A is 0.8-1.5 mol/L;

secondly, dipping an oxide carrier into the solution A, wherein the mass ratio of the oxide carrier to nickel ions is 1: 0.03-0.05; performing ultrasonic treatment at room temperature for 0.5-2 h, performing vacuum drying on the obtained dope at 80-100 ℃ for 15-24 h, and roasting in air at 600-700 ℃ for 3-5 h to obtain a catalyst precursor;

thirdly, weighing magnesium precursor salt, and dissolving the magnesium precursor salt in deionized water to prepare a mixed solution B, wherein the concentration of magnesium ions in the solution B is 0.1-0.2 mol/L;

step four, dipping the catalyst precursor obtained in the step two into the solution B, wherein the mass ratio of the oxide carrier to the auxiliary agent MgO is 1: 0.005-0.008; performing ultrasonic treatment at room temperature for 0.5-2 h, performing vacuum drying on the obtained sticky substance at 80-100 ℃ for 15-24 h, and roasting at 800-900 ℃ in air for 4-6 h to obtain CO promotion₂Activating the dissociated catalyst;

the oxide carrier is one of silicon dioxide, aluminum oxide, titanium dioxide, lanthanum oxide and zirconium oxide;

the catalyst needs 10% H before use₂Reducing the/Ar mixed gas for 30-90 min, wherein the reforming reaction conditions are that the volume ratio of raw material gas methane to carbon dioxide is 1:1, the reaction temperature is 750-900 ℃, the normal pressure is realized, and the space velocity of the raw material is 36000h^-1。

2. The CO-promoting catalyst of claim 1₂The preparation method of the activated dissociation catalyst is characterized by comprising the following steps:

step one, weighing nickel precursor salt, dissolving the nickel precursor salt in deionized water to prepare a mixed solution A, wherein the concentration of nickel ions in the solution A is 0.8-1.5 mol/L;

secondly, dipping an oxide carrier into the solution A, wherein the mass ratio of the oxide carrier to nickel ions is 1: 0.03-0.05; performing ultrasonic treatment at room temperature for 0.5-2 h, performing vacuum drying on the obtained dope at 80-100 ℃ for 15-24 h, and roasting in air at 600-700 ℃ for 3-5 h to obtain a catalyst precursor;

thirdly, weighing magnesium precursor salt, and dissolving the magnesium precursor salt in deionized water to prepare a mixed solution B, wherein the concentration of magnesium ions in the solution B is 0.1-0.2 mol/L;

step four, dipping the catalyst precursor obtained in the step two into the solution B, wherein the mass ratio of the oxide carrier to the auxiliary agent MgO is 1: 0.005-0.008; performing ultrasonic treatment at room temperature for 0.5-2 h, performing vacuum drying on the obtained sticky substance at 80-100 ℃ for 15-24 h, and roasting at 800-900 ℃ in air for 4-6 h to obtain CO promotion₂Activating the dissociated catalyst.

3. CO promotion according to claim 2₂The preparation method of the activation dissociation catalyst is characterized by comprising the following steps: in the first step, the precursor salt of nickel is one of nickel nitrate, nickel acetate, nickel sulfate, nickel chloride and nickel ethylenediamine.

4. CO promotion according to claim 3₂The preparation method of the activation dissociation catalyst is characterized by comprising the following steps: in the first step, the precursor salt of nickel is nickel ethylenediamine; the nickel ethylenediamine is prepared from nickel nitrate and ethylenediamine according to the molar ratio of 1: 3.

5. CO promotion according to claim 2₂The preparation method of the activation dissociation catalyst is characterized by comprising the following steps: in the third step, the magnesium precursor salt is one of magnesium nitrate, magnesium acetate, magnesium sulfate and magnesium chloride.

6. The CO-promoting catalyst of claim 1₂The use of an activated dissociation catalyst in methane carbon dioxide reforming reactions.

Images