阅读说明：本技术 一种用于二氧化碳甲烷化反应催化剂的制备方法 (Preparation method of catalyst for methanation reaction of carbon dioxide ) 是由 陈力群 李小强 于 2021-06-29 设计创作，主要内容包括：本发明涉及一种镍、钌负载沸石分子筛用于二氧化碳甲烷化反应催化剂的制备方法。本发明是利用分子筛为载体,在表面均匀负载镍,钌纳米颗粒,该催化剂用于Sabatier反应。本发明也是一种有效控制镍、钌均匀分散在分子筛表面及内部孔道的方法,由该发制备的催化剂可以用于Sabatier反应。所述的方法为旋转蒸发浸渍法。该方法以沸石分子筛为载体,通过旋转浸渍法将镍,钌前驱体负载在处理过的分子筛表面,实现金属均匀分散和强相互作用,再通过负压旋蒸干燥、高温煅烧、持续升温还原,最后得到高抗烧结、抗积碳性能的催化材料。本发明具有制备工艺简单、成本较低、对环境无污染、催化效率高等优点。(The invention relates to a preparation method of a catalyst for methanation reaction of carbon dioxide by using a nickel and ruthenium loaded zeolite molecular sieve. The invention uses molecular sieve as carrier, and nickel and ruthenium nanometer particles are loaded on the surface of the carrier, and the catalyst is used for Sabatier reaction. The invention also discloses a method for effectively controlling nickel and ruthenium to be uniformly dispersed on the surface and the inner pore channels of the molecular sieve, and the catalyst prepared by the method can be used for the Sabatier reaction. The method is a rotary evaporation dipping method. The method takes a zeolite molecular sieve as a carrier, nickel and ruthenium precursors are loaded on the surface of the treated molecular sieve by a rotary impregnation method to realize uniform dispersion and strong interaction of metals, and then the catalytic material with high sintering resistance and carbon deposition resistance is obtained by negative pressure rotary evaporation drying, high temperature calcination and continuous heating reduction. The invention has the advantages of simple preparation process, lower cost, no environmental pollution, high catalytic efficiency and the like.)

1. A preparation method of a catalyst for methanation reaction of carbon dioxide is characterized by comprising the following steps:

a. drying the molecular sieve in an oven for later use;

b. dissolving precursor salts of nickel and ruthenium in deionized water to prepare a precursor solution with the mass percentage of 1-20%;

c. adding the molecular sieve obtained in the step a into the precursor salt solution obtained in the step b, and performing ultrasonic dispersion to obtain a mixed suspension, wherein the liquid-solid mass ratio is 25-50: 1;

d. c, transferring the suspension obtained in the step c into a rotary steaming bottle, and performing rotary steaming at room temperature;

e. d, rotationally evaporating the suspension treated in the step d to remove deionized water, and drying to obtain a mixture;

f. continuously heating and calcining the mixture obtained in the step e in the air atmosphere;

g. drying the product obtained in step f in Ar, then in 5% H₂And (Ar) carrying out reduction reaction of the metal oxide in the atmosphere to finish the preparation of the catalyst.

2. The preparation method of the catalyst for methanation of carbon dioxide according to claim 1, wherein the molecular sieve is one of type A, type X or type Y.

3. The method according to claim 1, wherein the nickel precursor salt is one of nickel nitrate hexahydrate, nickel acetate tetrahydrate and nickel citrate, and the ruthenium precursor salt is one of a ruthenium (III) nitrosyl nitrate solution and a ruthenium (III) nitrosyl chloride hydrate.

4. The preparation method of the catalyst for methanation reaction of carbon dioxide as claimed in claim 1, wherein the particle size of the molecular sieve is 100-200 nm; the drying conditions were 100 ℃ for 12 h.

5. The preparation method of the catalyst for methanation reaction of carbon dioxide according to claim 1, wherein the ultrasonic dispersion time in the step b is 30-60 min; in the step c, the rotary evaporation speed is 5-10 rpm, and the rotary evaporation time is 6-12 h.

6. The preparation method of the catalyst for the methanation reaction of carbon dioxide according to claim 1, wherein in the step e, the rotary evaporation environment is 50 ℃, and the water ring vacuum pump is used for evacuating; the drying temperature is 100 ℃, and the drying time is 12 h.

7. The preparation method of the catalyst for methanation reaction of carbon dioxide according to claim 1, wherein the specific temperature rise and calcination conditions in step f are as follows:

heating to 250-300 ℃, maintaining the final temperature for 40-60 min, wherein the heating rate is 4.5 ℃/min; and then heating to 500-600 ℃, calcining for 3-5 h, wherein the air flow rate is 50ml/min, the heating rate is 2 ℃/min, and cooling to room temperature for 4-6 h.

8. The preparation method of the catalyst for methanation of carbon dioxide according to claim 1, wherein in the step g, the drying condition in Ar gas is 250 ℃, 1 h; the conditions of the metal oxide reduction reaction are as follows: at 5% H₂Continuously heating to 500-800 ℃ at the speed of 5 ℃/min in the (Ar) atmosphere, and reacting for 3-6 h.

Technical Field

The invention relates to the field of catalysts, in particular to a preparation method of a catalyst for methanation reaction of carbon dioxide.

Background

To limit the climate of global warming, reducing carbon dioxide emissions has become a formidable challenge in all countries. Over the past many years, CO has been utilized₂There is a great deal of interest in producing renewable energy carriers. CO2₂Can be converted into a variety of synthetic fuels, including methane, methanol, and dimethyl ether. Future large-scale production of fuels and chemicals, feedstock CO₂And H₂Is of crucial importance. Large amount of CO₂Available in industrial facilities such as coal fired power plants, this technology is currently referred to as CCU (carbon capture utilization). Direct CO separation from air₂The technology has also advanced greatly, and H₂Can be obtained continuously by electrolyzing water. By Sabatier reaction, H₂And CO₂Methane can be synthesized, and the reaction equation is as follows:

ΔH⁰r(298K)＝-165kJ/mol

this reaction is currently only used for air regeneration in the sealed capsule of the national aeronautics and astronautics administration (NASA) manned spacecraft.

This reaction is accompanied by side reactions, which generate toxic CO.

CO₂+H₂→CO+H₂O；ΔH⁰r(298K)＝41kJ/mol

In order to solve these problems, many studies have been reported, among which silica, α -alumina, titania, magnesia, zirconia and the like are used as a carrier, and nickel, iron, zirconium, cobalt, lanthanum and the like are used as an active metal. The noble metal catalyst has excellent catalytic performance and carbon deposition resistance, but has high price and limited resources, is greatly limited in industrial application, has low price and easy obtainment of nickel, and has catalytic activity equivalent to that of noble metal, so the nickel-based catalyst has very deep industrial application potential. In the Sabatier reaction, nickel favors the reverse water gas shift Reaction (RWGS), ruthenium shows higher activity for the CO hydrogenation reaction, and nickel ruthenium synergizes to promote the carbon dioxide methanation reaction, however, fewer reports are made on this bimetallic catalyst. The molecular sieve is used as a carrier, so that the report on the catalyst used for the Sabatier reaction is less, the molecular sieve can provide a porous environment as the carrier, the reaction is rapidly carried out, carbon deposition is not easy to occur, water produced by the reaction can be selectively absorbed, and the reaction conversion rate is improved. Therefore, it is still a difficult task to find a low-cost, anti-carbon deposition, high conversion and selectivity carbon dioxide methanation catalyst.

Disclosure of Invention

The invention aims to provide a preparation method of a catalyst for methanation reaction of carbon dioxide, which aims to solve the problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

1. a preparation method of a catalyst for methanation reaction of carbon dioxide comprises the following steps:

a. drying the molecular sieve in an oven for later use;

b. dissolving precursor salts of nickel and ruthenium in deionized water to prepare a precursor solution with the mass percentage of 1-20%;

c. adding the molecular sieve obtained in the step a into the precursor salt solution obtained in the step b, and performing ultrasonic dispersion to obtain a mixed suspension, wherein the liquid-solid mass ratio is 25-50: 1;

d. c, transferring the suspension obtained in the step c into a rotary steaming bottle, and performing rotary steaming at room temperature;

e. d, rotationally evaporating the suspension treated in the step d to remove deionized water, and drying to obtain a mixture;

f. continuously heating and calcining the mixture obtained in the step e in the air atmosphere;

g. drying the product obtained in step f in Ar, then in 5% H₂And (Ar) carrying out reduction reaction of the metal oxide in the atmosphere to finish the preparation of the catalyst.

Further, the molecular sieve is one of A type, X type or Y type.

Further, the nickel precursor salt is one of nickel nitrate hexahydrate, nickel acetate tetrahydrate and nickel citrate, and the ruthenium precursor salt is one of ruthenium (III) nitrosyl nitrate solution or ruthenium (III) nitrosyl chloride hydrate.

Further, the particle size of the molecular sieve is 100-200 nm; the drying conditions were 100 ℃ for 12 h.

Further, the ultrasonic dispersion time in the step b is 30-60 min; in the step c, the rotary evaporation speed is 5-10 rpm, and the rotary evaporation time is 6-12 h.

Further, in the step e, the rotary evaporation environment is 50 ℃, and the water ring vacuum pump is used for pumping out; the drying temperature is 100 ℃, and the drying time is 12 h.

Further, the specific temperature rise and calcination conditions in the step f are as follows:

heating to 250-300 ℃, maintaining the final temperature for 40-60 min, wherein the heating rate is 4.5 ℃/min; and then heating to 500-600 ℃, calcining for 3-5 h, wherein the air flow rate is 50ml/min, the heating rate is 2 ℃/min, and cooling to room temperature for 4-6 h.

Further, in the step g, the drying condition in Ar gas is 250 ℃ for 1 h; the conditions of the metal oxide reduction reaction are as follows: at 5% H₂Continuously heating to 500-800 ℃ at the speed of 5 ℃/min in the (Ar) atmosphere, and reacting for 3-6 h.

Compared with the prior art, the invention has the following technical effects:

the invention uses molecular sieve as carrier, and nickel and ruthenium nanometer particles are loaded on the surface of the carrier, and the catalyst is used for Sabatier reaction. The invention also discloses a method for effectively controlling nickel and ruthenium to be uniformly dispersed on the surface and the inner pore channels of the molecular sieve, and the catalyst prepared by the method can be used for the Sabatier reaction. The method is a rotary evaporation dipping method. The method takes a zeolite molecular sieve as a carrier, nickel and ruthenium precursors are loaded on the surface of the treated molecular sieve by a rotary impregnation method to realize uniform dispersion and strong interaction of metals, and then the catalytic material with high sintering resistance and carbon deposition resistance is obtained by negative pressure rotary evaporation drying, high temperature calcination and continuous heating reduction. The invention has the advantages of simple preparation process, lower cost, no environmental pollution, high catalytic efficiency and the like.

The preparation method has the advantages of low cost, high operability and environmental friendliness. The catalyst can be used for solving the problem of high-temperature sintering agglomeration of active components in the methanation reaction of CO2, and ensures high conversion rate of CO2 and high selectivity to CH 4.

Drawings

FIG. 1 shows the application of the X-type molecular sieve loaded with nickel and ruthenium in CO obtained in example 1 of the present invention₂CO in methanation reactions₂Conversion and p-CH₄Selectivity as a function of reaction time scatter plot.

Detailed Description

The following detailed description of the embodiments of the invention refers to the accompanying drawings.

Example 1

10g of 13X molecular sieve was weighed into a crucible and dried overnight at 100 ℃. 2.477g of nickel nitrate hexahydrate and 0.314g of ruthenium trinitronitrosyl were weighed out and dissolved in 250ml of deionized water. Slowly adding the dried 13X molecular sieve into the aqueous solution containing the nickel and the ruthenium in the ultrasonic process, and continuing to perform ultrasonic dispersion for 30 min. The supernatant was transferred to a rotary evaporator and rotary evaporated at 10rpm for 8h at room temperature. And starting a water circulation vacuum pump, heating the water bath kettle to 50 ℃, performing rotary evaporation for 2 hours, and evaporating the deionized water in the suspension to dryness. The rotary-dried powder was moved to an oven for drying at 100 ℃ for 12 h. Calcining the dried powder, in an air atmosphere, raising the temperature to 300 ℃ at the air flow rate of 50ml/min and the heating rate of 4.5 ℃/min, maintaining for 40min, then adjusting the heating rate to 500 ℃ at the heating rate of 2 ℃/min, maintaining for 5h, and naturally cooling to room temperature. And (3) continuously heating and reducing the calcined powder by hydrogen, firstly drying the calcined powder in Ar at 250 ℃ for 1H, then continuously heating the calcined powder to 500 ℃ at the speed of 5 ℃/min in the atmosphere of 5% H2(Ar) to perform a reduction reaction for 5H, and cooling the calcined powder to room temperature in the atmosphere of Ar to finish the preparation of the catalyst.

The catalysts described above were tested for catalytic activity: weighing 0.9g of upper catalyst powder, placing in a fixed bed quartz tube reactor, and introducing CO₂、H₂And N₂Mixed gas, H2 flow rate 40ml/min, CO₂Flow rate 10ml/min, N₂The flow rate was 150 ml/min. The activity test temperature is 400 ℃ and CO₂The conversion rate is as high as 80, is close to the reaction equilibrium conversion rate, and is used for treating CH₄The selectivity reaches 98.5%, and the reaction lasts for 4 hours, and the conversion rate and the selectivity are not changed.

Example 2

10g of 13X molecular sieve was weighed into a crucible and dried overnight at 100 ℃. 2.477g of nickel nitrate hexahydrate and 0.314g of ruthenium trinitronitrosyl were weighed out and dissolved in 250ml of deionized water. Slowly adding the dried 13X molecular sieve into the aqueous solution containing the nickel and the ruthenium in the ultrasonic process, and continuing to perform ultrasonic dispersion for 40 min. The supernatant was transferred to a rotary evaporator and rotary evaporated at 5rpm for 8h at room temperature. And starting a water circulation vacuum pump, heating the water bath kettle to 50 ℃, performing rotary evaporation for 2 hours, and evaporating the deionized water in the suspension to dryness. The rotary-dried powder was moved to an oven for drying at 100 ℃ for 12 h. Calcining the dried powder, in an air atmosphere, raising the temperature to 300 ℃ at the air flow rate of 50ml/min and the heating rate of 4.5 ℃/min, maintaining for 40min, then adjusting the heating rate to 500 ℃ at the heating rate of 2 ℃/min, maintaining for 5h, and naturally cooling to room temperature. And (3) continuously heating and reducing the calcined powder by hydrogen, firstly drying the calcined powder in Ar at 250 ℃ for 1H, then continuously heating the calcined powder to 500 ℃ at the speed of 5 ℃/min in the atmosphere of 5% H2(Ar) to perform a reduction reaction for 5H, and cooling the calcined powder to room temperature in the atmosphere of Ar to finish the preparation of the 13X molecular sieve catalyst with 5% of nickel load and 1% of ruthenium load.

The catalysts described above were tested for catalytic activity: weighing 0.9g of upper catalyst powder, placing in a fixed bed quartz tube reactor, and introducing CO₂、H₂And N₂Mixed gas, H2 flow rate 40ml/min, CO₂Flow rate 10ml/min, N₂The flow rate was 150 ml/min. The activity test temperature is 400 ℃ and CO₂The conversion rate is as high as 80, is close to the reaction equilibrium conversion rate, and is used for treating CH₄The selectivity reaches 98.5%, and the reaction lasts for 4 hours, and the conversion rate and the selectivity are not changed.

Example 3

10g of type A molecular sieve was weighed into a crucible and dried overnight at 100 ℃. 4.240g of nickel acetate tetrahydrate and 0.157g of ruthenium trinitronitrosyl were weighed out and dissolved in 300ml of deionized water. Slowly adding the dried A-type molecular sieve into the aqueous solution containing the nickel and the ruthenium in the ultrasonic treatment, and continuing to perform ultrasonic dispersion for 50 min. The supernatant was transferred to a rotary evaporator and rotary evaporated at 5rpm for 10h at room temperature. And starting a water circulation vacuum pump, heating the water bath kettle to 50 ℃, performing rotary evaporation for 3 hours, and evaporating the deionized water in the suspension to dryness. The rotary-dried powder was moved to an oven for drying at 100 ℃ for 12 h. Calcining the dried powder, in an air atmosphere, raising the temperature at a speed of 50ml/min and at a speed of 4.5 ℃/min to 250 ℃ for 60min, then adjusting the temperature at a speed of 2 ℃/min to 600 ℃ for 3h, and naturally cooling to room temperature. And (3) continuously heating and reducing the calcined powder by hydrogen, firstly drying the calcined powder in Ar at 250 ℃ for 1H, then continuously heating the calcined powder to 750 ℃ at the speed of 5 ℃/min in the atmosphere of 5% H2(Ar) to perform a reduction reaction for 3H, and cooling the calcined powder to room temperature in the atmosphere of Ar to finish the preparation of the A-type molecular sieve catalyst with the nickel load of 10% and the ruthenium load of 0.5%.

The catalysts described above were tested for catalytic activity: weighing 0.9g of upper catalyst powder, placing in a fixed bed quartz tube reactor, and introducing CO₂、H₂And N₂Mixed gas, H2 flow rate 40ml/min, CO₂Flow rate 10ml/min, N₂The flow rate was 150 ml/min. The activity test temperature is 360 ℃, and CO is₂The conversion rate is as high as 80, is close to the reaction equilibrium conversion rate, and is used for treating CH₄The selectivity reaches 95 percent.

Example 4

Molecular sieve type 10gY was weighed into a crucible and dried overnight at 100 ℃. 2.519g of hydrated nickel citrate and 0.157g of ruthenium trinitronitrosyl were weighed out and dissolved in 200ml of deionized water. Slowly adding the dried Y-type molecular sieve into the aqueous solution containing the nickel and the ruthenium in the ultrasonic process, and continuing to perform ultrasonic dispersion for 50 min. The supernatant was transferred to a rotary evaporator and rotary evaporated at 10rpm for 6h at room temperature. And starting a water circulation vacuum pump, heating the water bath kettle to 50 ℃, performing rotary evaporation for 2 hours, and evaporating the deionized water in the suspension to dryness. The rotary-dried powder was moved to an oven for drying at 100 ℃ for 12 h. Calcining the dried powder, in an air atmosphere, raising the temperature at a speed of 50ml/min and at a speed of 4.5 ℃/min to 300 ℃ for 50min, then adjusting the temperature at a speed of 2 ℃/min to 500 ℃ for 4h, and naturally cooling to room temperature. And (3) continuously heating and reducing the calcined powder by hydrogen, firstly drying the calcined powder in Ar at 250 ℃ for 1H, then continuously heating the calcined powder to 600 ℃ at the speed of 5 ℃/min in the atmosphere of 5% H2(Ar) to perform a reduction reaction for 4H, and cooling the calcined powder to room temperature in the atmosphere of Ar to finish the preparation of the Y-type molecular sieve catalyst with 8% of nickel load and 0.5% of ruthenium load.

The catalysts described above were tested for catalytic activity: weighing 0.9g of upper catalyst powder, placing in a fixed bed quartz tube reactor, and introducing CO₂、H₂And N₂Mixed gas, H2 flow rate 40ml/min, CO₂Flow rate 10ml/min, N₂Flow rate of flow150 ml/min. The activity test temperature is 360 ℃, and CO is₂The conversion rate is as high as 80, is close to the reaction equilibrium conversion rate, and is used for treating CH₄The selectivity reaches 97 percent.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, substitutions, modifications and variations may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.