Preparation method of high-temperature-resistant CO2 methanation catalyst and application thereof

Abstract

The invention discloses a preparation method and application of a high-temperature resistant CO2 methanation catalyst. The method comprises the following steps: uniformly grinding coal powder, potassium salt, nickel salt, magnesium salt and aluminum salt to obtain a uniform mixture; calcining the mixture at 600-900°C in a flowing inert atmosphere for 2-8 hours; after the calcination, cooling the mixture to room temperature while continuing to flow in the inert atmosphere, transferring the mixture to a water bath for reflux treatment to obtain a solid powder sample, filtering and washing the solid powder sample until the pH value of the supernatant is neutral, washing with ethanol, filtering and drying to obtain a catalyst precursor; kneading, granulating and steam curing the catalyst precursor to obtain a high-temperature resistant methanation catalyst. The high-temperature resistant carbon dioxide methanation catalyst precursor is prepared in an inert atmosphere by a melting method in one step. The conditions are easy to control, and subsequent high-temperature calcination and reduction treatment are not required, thereby eliminating the need for the catalyst to undergo a high-temperature reduction process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a high-temperature-resistant CO2 methanation catalyst preparation method and application thereof. BACKGROUND

[0002] Natural gas is a kind of efficient, safe and clean fossil energy, and its proportion in global energy consumption is increasing year by year. With the enhancement of people's environmental protection consciousness and the improvement of life quality, the demand for natural gas is also increasing year by year. However, the energy structure of China is "rich in coal, short of oil and less gas", and the development of coal-to-natural gas using relatively abundant coal resources can not only make up for the situation of insufficient natural gas resources in China and narrow the supply-demand gap of natural gas in China, but also has important strategic significance for realizing diversification of oil and gas resources, energy security, energy saving and emission reduction and the like.

[0003] Methanation reaction is the core technology of coal-to-natural gas, and the methanation reaction is a strong exothermic reaction. In the usual gas components, 74℃ of adiabatic temperature rise can be generated by 1% of CO methanation, and 60℃ of adiabatic temperature rise can be generated by 1% of CO2 methanation. The large amount of heat released by the methanation reaction can cause the reactor bed to instantaneously overheat, resulting in high-temperature sintering of the catalyst and deactivation. Meanwhile, under high-temperature conditions, carbon deposition reaction of methane on the surface of the nickel-based catalyst is easy to occur, resulting in reduction of the activity of the catalyst. Therefore, high-temperature sintering and carbon deposition of the catalyst are the keys to affecting the service life of the methanation catalyst. Although the local high temperature of the reactor bed can be improved by changing the process conditions or using a tube reactor and the like, a large amount of investment cost needs to be increased, and the technology is not mature, so development of a methanation catalyst with excellent anti-sintering and anti-carbon deposition performance is the key to solving the deactivation of the catalyst.

[0004] The methanation catalysts prepared in Chinese patents CN102029162 and CN102259004A are both prepared by a homogeneous precipitation method. The prepared methanation catalysts have uniform dispersion of each component, good activity at high temperature, but the NiO and Al2O3 in the catalyst are combined closely, the catalyst reduction temperature is high, and the catalysts have poor thermal stability and anti-carbon deposition performance, which are not conducive to industrial production. The methanation catalyst prepared in Chinese patent CN102836718A is prepared by first preparing a high-temperature-resistant and anti-sintering hexaaluminate carrier, and then preparing the methanation catalyst by impregnation of the active component NiO. Since the active component NiO is loaded on the hexaaluminate carrier, the prepared methanation catalyst has good thermal stability, but the specific surface area of the hexaaluminate carrier is low, and the preparation process is complex, which is not conducive to industrial production. SUMMARY

[0005] In order to solve the problems in the prior art, the application provides a preparation method of a high-temperature-resistant CO2 methanation catalyst and application of the catalyst.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows: a preparation method of a high-temperature-resistant CO2 methanation catalyst, comprising the following steps:

[0007] Grinding the coal powder, potassium salt, nickel salt, magnesium salt and aluminum salt uniformly to obtain a uniform mixture;

[0008] Baking the mixture in a flowing inert atmosphere at 600-900 DEG C for 2-8 hours;

[0009] After the baking is completed, the mixture is continuously cooled to room temperature in the flowing inert atmosphere, is transferred to a water bath condition for reflux treatment, a solid powder sample is obtained, the solid powder sample is washed by suction filtration until the pH value of the supernatant is neutral, then the catalyst precursor is obtained by washing with ethanol, suction filtration and drying;

[0010] The catalyst precursor is kneaded, granulated and shaped, and is maintained by water vapor to obtain the high-temperature-resistant methanation catalyst.

[0011] Further, the grinding the coal powder, potassium salt, nickel salt, magnesium salt and aluminum salt uniformly comprises: mixing (20-90) parts of the coal powder, (50-200) parts of the potassium salt, (15-35) parts of the nickel salt, (25-50) parts of the magnesium salt and (250-450) parts of the aluminum salt according to the mass fraction, and grinding to more than 200 mesh by using a grinding machine.

[0012] Further, the nickel salt is one or more mixtures of nickel nitrate, nickel acetate and nickel carbonate.

[0013] Further, the potassium salt is one or more mixtures of potassium hydroxide, potassium bicarbonate and potassium carbonate.

[0014] Further, the magnesium salt is one or more mixtures of magnesium nitrate, magnesium acetate and magnesium sulfate.

[0015] Further, the aluminum salt is one or a mixture of two of Al(NO3)3·9H2O and Al(CH3COO)2OH.

[0016] Further, during the baking, the inert atmosphere is argon, helium or carbon dioxide atmosphere, the space velocity of the baking is 500-3000 h -1 , the pressure is 0.1-0.15 MPa; and the baking is performed in a corundum tube furnace.

[0017] Further, in 80-100 DEG C water bath reflux 2-4h, with deionized water to extract washing until the supernatant pH value is neutral, then washed with anhydrous ethanol repeatedly, finally placed in the oven 80-110 DEG C drying 8-18h.

[0018] Based on the preparation method, the high-temperature-resistant methanation catalyst is applied to the methanation catalysis of coal-to-synthetic natural gas.

[0019] Compared with the prior art, the application has at least the following beneficial effects:

[0020] The application provides a high-temperature-resistant carbon dioxide methanation catalyst and a preparation method thereof, and the high-temperature-resistant carbon dioxide methanation catalyst precursor is prepared by a one-step method in an inert atmosphere by using a melting method, the process is simple, and the conditions are easy to control; the catalyst does not need subsequent high-temperature calcination and reduction treatment, the active center mononickel and active nickel oxide are generated in one step in the preparation process, the process of high-temperature reduction required by the catalyst is omitted, the average use temperature of the catalyst is lower than the calcination temperature, the catalyst has better high-temperature resistance in the later use process, meanwhile, the catalyst generates a uniformly dispersed porous carbon structure in the preparation process, the rich micropore and mesopore structures of the porous carbon are fully utilized, the active component nickel metal reaches atomic level distribution, which is helpful to improve the dispersity of the active component and greatly improve the utilization rate of the active component; the prepared catalyst has good high-temperature stability, strong anti-carbon deposition and anti-sintering performance, and the catalyst is suitable for the coal-to-synthetic natural gas process technology under different working conditions, and is especially suitable for the synthetic gas-to-natural gas process rich in CO2. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is an SEM (x6000) of the high-temperature-resistant CO2 methanation catalyst product of the application.

[0022] Figure 2 It is an SEM (x1000) of the high-temperature-resistant CO2 methanation catalyst product of the application.

[0023] Figure 3 It is an XRD spectrum of the high-temperature-resistant CO2 methanation catalyst product of the application. DETAILED DESCRIPTION

[0024] The technical solutions of the application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0025] Example 1:

[0026] Take 20g of coal powder, 50g of potassium hydroxide, 15g of nickel nitrate, 200g of aluminum nitrate, 25g of magnesium nitrate mixed together, use the grinder to grind to more than 200 mesh, get the uniform mixture of sticky state; The above mixture is transferred to a corundum tube furnace, calcined at 600℃ for 8 hours in argon atmosphere; After calcination, continue to cool to room temperature under inert atmosphere, then treat in 100℃ water bath reflux for 4h, wash with deionized water until the supernatant pH value is neutral, finally repeat washing with anhydrous ethanol for 3 times, put in the oven at 110℃ for 8h drying, get the high temperature resistant methanation catalyst.

[0027] Example 2:

[0028] Take 20g of coal powder, 50g of potassium hydroxide, 15g of nickel nitrate, 200g of aluminum nitrate, 25g of magnesium nitrate mixed together, use the grinder to grind to more than 200 mesh, get the uniform mixture of sticky state; The above mixture is transferred to a corundum tube furnace, calcined at 600℃ for 8 hours in argon atmosphere; After calcination, continue to cool to room temperature under inert atmosphere, then treat in 100℃ water bath reflux for 4h, wash with deionized water until the supernatant pH value is neutral, finally repeat washing with anhydrous ethanol for 3 times, put in the oven at 110℃ for 8h drying, get the high temperature resistant methanation catalyst.

[0029] Example 3:

[0030] Take 20g of coal powder, 50g of potassium hydroxide, 15g of nickel nitrate, 200g of aluminum nitrate, 25g of magnesium nitrate mixed together, use the grinder to grind to more than 200 mesh, get the uniform mixture of sticky state; The above mixture is transferred to a corundum tube furnace, calcined at 600℃ for 8 hours in argon atmosphere; After calcination, continue to cool to room temperature under inert atmosphere, then treat in 100℃ water bath reflux for 4h, wash with deionized water until the supernatant pH value is neutral, finally repeat washing with anhydrous ethanol for 3 times, put in the oven at 110℃ for 8h drying, get the high temperature resistant methanation catalyst.

[0031] Example 4:

[0032] Take 20g of coal powder, 50g of potassium hydroxide, 15g of nickel nitrate, 200g of aluminum nitrate, 25g of magnesium nitrate mixed together, use the grinder to grind to more than 200 mesh, get the uniform mixture of sticky state; The above mixture is transferred to a corundum tube furnace, calcined at 600℃ for 8 hours in argon atmosphere; After calcination, continue to cool to room temperature under inert atmosphere, then treat in 100℃ water bath reflux for 4h, wash with deionized water until the supernatant pH value is neutral, finally repeat washing with anhydrous ethanol for 3 times, put in the oven at 110℃ for 8h drying, get the high temperature resistant methanation catalyst.

[0033] Example 5:

[0034] Take 45g of coal powder, 50g of potassium bicarbonate, 30g of nickel nitrate, 270g of aluminum acetate, 25g of magnesium nitrate and magnesium acetate mixed together, ground by a grinder to more than 200 mesh, to get a viscous uniform mixture; the mixture is transferred to a corundum tube furnace, calcined at 800°C for 3 hours in a helium atmosphere; after calcination, continue to cool to room temperature under inert atmosphere, then reflux in a 70°C water bath for 4h, washed with deionized water until the supernatant pH value is neutral, finally washed with anhydrous ethanol for 3 times, placed in an oven at 110°C for 8h drying, to get the application of high temperature resistant methanation catalyst.

[0035] Example 6:

[0036] Take 90g of coal powder, 200g of potassium bicarbonate, 25g of nickel nitrate and nickel acetate, 450g of aluminum acetate, 50g of magnesium nitrate mixed together, ground by a grinder to more than 200 mesh, to get a viscous uniform mixture; the mixture is transferred to a corundum tube furnace, calcined at 700°C for 4 hours in an argon atmosphere; after calcination, continue to cool to room temperature under inert atmosphere, then reflux in a 100°C water bath for 2h, washed with deionized water until the supernatant pH value is neutral, finally washed with anhydrous ethanol for 3 times, placed in an oven at 80°C for 10h drying, to get the application of high temperature resistant methanation catalyst.

[0037] Example 7:

[0038] Take 65g of coal powder, 103g of potassium carbonate, 28g of nickel nitrate, 400g of aluminum acetate, 25g of magnesium nitrate mixed together, ground by a grinder to more than 200 mesh, to get a viscous uniform mixture; the mixture is transferred to a corundum tube furnace, calcined at 900°C for 5 hours in a helium atmosphere; after calcination, continue to cool to room temperature under inert atmosphere, then reflux in a 90°C water bath for 4h, washed with deionized water until the supernatant pH value is neutral, finally washed with anhydrous ethanol for 3 times, placed in an oven at 90°C for 18h drying, to get the application of high temperature resistant methanation catalyst.

[0039] Example 8:

[0040] 85g of coal powder, 160g of potassium carbonate, 35g of nickel nitrate, 300g of aluminum nitrate and aluminum acetate, and 30g of magnesium sulfate are mixed together, ground to more than 200 mesh by using a grinder to obtain a viscous uniform mixture; the mixture is transferred to a corundum tube furnace, calcined at 900°C for 2 hours in a carbon dioxide atmosphere; after calcination, the temperature is continuously lowered to room temperature under an inert atmosphere, then refluxed at 100°C for 2h in a water bath, washed by using deionized water until the pH value of the supernatant is neutral, finally washed repeatedly 3 times by using anhydrous ethanol, and dried in an oven at 110°C for 12h to obtain a high-temperature-resistant CO2 methanation catalyst.

[0041] Figure 1 SEM (x6000) of the high-temperature-resistant CO2 methanation catalyst product prepared in Example 5 of the present application, Figure 2 SEM (x1000) of the high-temperature-resistant CO2 methanation catalyst product of the present application is shown, and from the SEM spectrum, it can be seen that the catalyst forms a uniformly distributed porous carbon structure, and nano-sized particles are uniformly distributed on the surface of the porous carbon structure. Combined with the XRD spectrum of the high-temperature-resistant CO2 methanation catalyst product, the particles dispersed on the surface of the porous carbon structure are the methanation active species nickel oxide, the active center elemental nickel, and the nickel-magnesium spinel serving as a catalyst structure support.

[0042] The products prepared in Examples 1-8 are tested, including the following steps:

[0043] The finished catalyst in the above examples is loaded into an adiabatic fixed-bed reaction evaluation device, the space velocity is 10000h-1 -1 , the pressure is 3MPa, and the raw material gas is H2 / CO2=4 in different proportions, and the activity data under different temperature conditions are listed in Table 1:

[0044] Table 1: Catalytic activity data

[0045]

[0046]

[0047] The activity data of each example is listed in Table 1. As can be seen from Table 1, the catalytic activity data of the CO2 methanation catalyst prepared by the present application is that the temperature is 300-500°C, and the CO2 conversion rate and CH4 selectivity are significantly improved, and within the temperature range, the higher the temperature, the higher the conversion rate and selectivity. That is, the CO2 methanation catalyst prepared by the present application meets the application conditions in the synthesis of natural gas. It also shows that the methanation catalyst introduces a porous carbon material with a large specific surface area, and the carrier is modified by introducing alkali metals and alkaline earth metals to prepare a composite multi-level pore carrier, which improves the utilization rate of the active component and improves the activity and high-temperature resistance of the catalyst.

Claims

1. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: The following steps are involved: 20 g of coal powder, 50 g of potassium hydroxide, 15 g of nickel nitrate, 200 g of aluminum nitrate, and 25 g of magnesium nitrate were weighed, mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 600° C. in an argon atmosphere for 8 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in a 100° C. water bath for 4 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 110° C. for 8 hours to obtain a high-temperature resistant methanation catalyst.

2. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 55 g of coal powder, 75 g of potassium carbonate, 20 g of nickel nitrate, 300 g of aluminum nitrate, and 30 g of magnesium nitrate were weighed, mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 900° C. in an argon atmosphere for 4 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, then refluxed in a 100° C. water bath for 2 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 90° C. for 12 hours to obtain a high-temperature resistant methanation catalyst.

3. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 70 g of coal powder, 87 g of potassium carbonate and potassium bicarbonate, 33 g of nickel acetate, 340 g of aluminum nitrate, and 35 g of magnesium acetate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 750° C. in a carbon dioxide atmosphere for 6 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in an 80° C. water bath for 3 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol for 3 times, and dried in an oven at 90° C. for 12 hours to obtain a high-temperature resistant methanation catalyst.

4. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 34 g of coal powder, 120 g of potassium carbonate, 26 g of nickel acetate, 280 g of aluminum nitrate, and 40 g of magnesium acetate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 700° C. in a carbon dioxide atmosphere for 4 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in an 80° C. water bath for 4 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 90° C. for 15 hours to obtain a high-temperature resistant methanation catalyst.

5. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 45 g of coal powder, 50 g of potassium bicarbonate, 30 g of nickel nitrate, 270 g of aluminum acetate, and 25 g of magnesium nitrate and magnesium acetate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 800° C. in a helium atmosphere for 3 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in a 70° C. water bath for 4 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol for 3 times, and dried in an oven at 110° C. for 8 hours to obtain a high-temperature resistant methanation catalyst.

6. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 90 g of coal powder, 200 g of potassium bicarbonate, 25 g of nickel nitrate and nickel acetate, 450 g of aluminum acetate, and 50 g of magnesium nitrate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the mixture was transferred to a corundum tube furnace and calcined at 700° C. in an argon atmosphere for 4 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, then refluxed in a 100° C. water bath for 2 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 80° C. for 10 hours to obtain a high-temperature resistant methanation catalyst.

7. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 65 g of coal powder, 103 g of potassium carbonate, 28 g of nickel nitrate, 400 g of aluminum acetate, and 25 g of magnesium nitrate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the above mixture was transferred to a corundum tube furnace and calcined at 900° C. in a helium atmosphere for 5 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in a 90° C. water bath for 4 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 90° C. for 18 hours to obtain a high-temperature resistant methanation catalyst.

8. A method for preparing a high-temperature resistant CO2 methanation catalyst, characterized in that: 85 g of coal powder, 160 g of potassium carbonate, 35 g of nickel nitrate, 300 g of aluminum nitrate and aluminum acetate, and 30 g of magnesium sulfate were weighed and mixed together, and ground into a size larger than 200 mesh using a grinder to obtain a viscous uniform mixture; the above mixture was transferred to a corundum tube furnace and calcined at 900° C. in a carbon dioxide atmosphere for 2 hours; after the calcination, the mixture was further cooled to room temperature in an inert atmosphere, and then refluxed in a 100° C. water bath for 2 hours, filtered and washed with deionized water until the pH value of the supernatant was neutral, and finally washed repeatedly with anhydrous ethanol three times, and dried in an oven at 110° C. for 12 hours to obtain a high-temperature resistant methanation catalyst.

9. Use of the high-temperature resistant CO2 methanation catalyst obtained by the preparation method according to any one of claims 1 to 8, characterized in that: Used in methanation catalysis of coal to synthetic natural gas.

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