CN110270339A - A kind of hollow barium zirconate CO methanation catalyst of original position nickel doping - Google Patents

Abstract

The invention relates to the field of energy catalysis, in particular to an in-situ nickel-doped hollow barium zirconate CO methanation catalyst. The catalyst uses barium zirconate as a carrier and nickel oxide as an active component, and the active component nickel oxide is doped in the lattice of barium zirconate in situ by a hydrothermal synthesis method. The mass percentage of each component of the catalyst is: nickel oxide is 10-30%, and the balance is barium zirconate carrier. The catalyst obtained by the invention has the advantages of simple catalyst preparation, high mechanical strength, high catalytic activity, good thermal stability, strong anti-carbon deposition and anti-sintering performance and low cost, and can be well applied to CO methanation reaction.

Description

An in-situ nickel-doped hollow barium zirconate CO methanation catalyst

technical field

The invention relates to the field of energy catalysis, in particular to an in-situ nickel-doped hollow barium zirconate CO methanation catalyst.

Background technique

my country is a country rich in coal, poor in oil and less in gas. Coal occupies a major position in my country's primary energy consumption structure. However, about 80% of the coal consumed is directly converted through combustion, the utilization rate of heat energy is low, and a large amount of pollutants are emitted at the same time. Therefore, it is of great significance to develop efficient, low-carbon and clean coal resource utilization technologies. The gas obtained from the pyrolysis and gasification of coal or biomass mainly contains H ₂ and CO. The main components of coke oven gas in the coking industry are also H ₂ and CO. These CO-containing mixed gases can pass through processes such as transformation and purification. The methanation reaction produces CH ₄ . This can not only promote the efficient and clean comprehensive utilization of coal but also improve the heat density of gas, and at the same time provide a feasible way to fill the gap of natural gas demand in my country. The methanation process mainly involves the following reactions:

CO + 3H ₂ → CH ₄ + H ₂ O Δ _r H _m = –206 kJ/mol

The reaction is a strong exothermic reaction, and the instantaneous flying temperature in the catalyst bed will cause the methanation catalyst to sinter and lose its activity. In addition, since the methanation reaction itself is easy to deactivate the catalyst due to carbon deposition, the anti-carbon deposition performance and high temperature resistance of the catalyst will directly affect the life of the catalyst. Therefore, developing a methanation catalyst that has high catalytic activity and can work stably for a long time at high temperature is one of the key factors in the synthesis gas methanation process.

The CO methanation catalysts reported earlier are mostly used to remove a small amount of CO impurities in H ₂ -rich systems. The commonly used catalysts are Ni and Ru transition metals supported on oxides, and the oxide supports used are Al ₂ O ₃ , SiO _2. TiO ₂ , ZrO ₂ , MgO, etc. These catalysts can basically achieve ideal effects in the methanation reaction of synthesizing NH ₃ and removing low-concentration CO in the fuel cell industry. The reaction is very exothermic, which will cause serious carbon deposition and sintering. Therefore, it is of great significance to develop new catalysts suitable for high-concentration CO methanation.

Perovskite oxides have been widely studied in catalytic oxidation, environmental catalysis, catalytic hydrogenation, hydrocracking, photocatalysis, solid fuel cells, and chemical sensors. The molecular formula of the perovskite composite oxide is ABO ₃ , usually A is an alkaline earth metal element or a La series element, and B is mainly a transition metal. It is generally believed that the A-site ion has no catalytic activity, only affects the thermal stability of the perovskite catalyst, and usually plays a role in stabilizing the structure; the B-site transition metal is often the active component of the catalyst, and the partial substitution of the B-site can change the catalyst. catalytic activity. However, perovskite materials have relatively few applications in CO methanation, so they have very broad application prospects.

SUMMARY OF THE INVENTION

The invention adopts barium zirconate with high mechanical strength, good thermal stability and large specific surface area as a carrier, and adopts a simple hydrothermal method to dope the active component nickel into the barium zirconate skeleton, so as to prepare a kind of barium zirconate with high reaction activity, Anti-sintering, anti-carbon deposition carbon monoxide methanation catalyst. It not only improves the activity and stability of the catalyst, but also broadens the application of perovskite-type materials in the field of catalysis.

Based on this, one of the objectives of the present invention is to provide an in-situ nickel-doped hollow barium zirconate CO methanation catalyst.

In order to achieve the above object, the present invention adopts the following technical solutions:

An in-situ nickel-doped hollow barium zirconate CO methanation catalyst comprises an active component and a carrier, wherein the active component is nickel oxide; the carrier is barium zirconate.

Preferably, based on the content of nickel oxide, the total mass of the catalyst is 100%, and the percentage of each component in the total weight of the catalyst is: the active component nickel oxide is 10-30%, and the balance is barium zirconate carrier.

The in-situ nickel-doped hollow barium zirconate CO methanation catalyst of the present invention adopts barium zirconate with excellent mechanical strength and good thermal stability as a carrier, which can improve the tolerance of the catalyst during high temperature reaction ; The hydrothermal method adopted makes the active component nickel oxide doped in the lattice of barium zirconate in situ, which enhances the force between nickel oxide and carrier barium zirconate; because barium zirconate belongs to the perovskite type There are a lot of oxygen vacancies in the material, so the anti-carbon deposition performance of the catalyst is also enhanced.

Another object of the present invention is to provide a method for preparing the above catalyst.

The in-situ nickel-doped hollow barium zirconate CO methanation catalyst of the present invention is carried out as follows:

Add the calculated amount of soluble zirconium salt and barium nitrate to a certain amount of deionized water, stir for 20-40 min to make it evenly mixed, then add the calculated amount of soluble nickel salt, and then stir for 20-40 min to make it evenly mixed. Then, the mixed solution was added to a certain amount of potassium hydroxide solution with a certain concentration, vigorously stirred for 30-60 min, and then loaded into a 100 mL hydrothermal reactor with a polytetrafluoroethylene lining. The reaction kettle was placed in a 200 ^o C oven for 24 hours and taken out, cooled to room temperature naturally, and the product was washed with deionized water, glacial acetic acid and absolute ethanol for several times to remove excess alkali and carbonate impurities, and centrifuged. After drying, it was dried in an oven at 60-80 ^o C, and after being fully dried, it was calcined in a muffle furnace at 400-600 ^o C for 2-6 h, and the obtained catalyst was marked as NiO/BaZrO ₃ .

Preferably, the soluble zirconium salt is any one of zirconium oxychloride, zirconium oxynitrate and zirconium nitrate.

Preferably, the soluble nickel salt is any one of nickel acetate, nickel sulfate, nickel nitrate or nickel chloride.

Preferably, the loading of the soluble nickel salt is 10-30%.

Preferably, the concentration of the potassium hydroxide solution is 10～20 mol/L.

Preferably, the amount of the potassium hydroxide solution is 50-70 mL.

Compared with the prior art, the present invention has the following beneficial effects:

The invention adopts the hydrothermal method to prepare the catalyst of in-situ nickel-doped barium zirconate, and the prepared catalyst has the characteristics of high mechanical strength, high catalytic activity, good thermal stability, anti-carbon deposition, strong anti-sintering performance, etc. It exhibits excellent catalytic performance in the chemical reaction.

Description of drawings

Fig. 1 is the XRD spectrum of the different samples of embodiment 1, 2, 3, 4;

FIG. 2 is an SEM image of the 10Ni/BaZrO ₃ sample in Example 2 at a magnification of 60,000 times.

Detailed ways

The technical solutions of the present invention will be further described below through examples, but the present invention is not limited to the following examples.

Example 1

Preparation _of the carrier BaZrO3:

0.538 g ZrOCl ₂ ·8H ₂ O and 0.480 g Ba(NO ₃ ) ₂ were added to 10 mL of deionized water, and stirred for 20 min to make the mixture uniform. Then, the mixed solution was added to 50 mL (10 mol/L) KOH solution, stirred vigorously for 40 min, and then charged into a 100 mL hydrothermal reactor with a polytetrafluoroethylene lining. The reaction kettle was placed in a 200 ^o C oven for 24 hours and taken out, cooled to room temperature naturally, and the product was washed with deionized water, glacial acetic acid and absolute ethanol for several times to remove excess alkali and carbonate impurities, and centrifuged. After drying, it was dried in an oven at 60 ^o C, and after being fully dried, it was calcined in a muffle furnace at 400 ^o C for 2 h to obtain BaZrO ₃ .

Example 2

Preparation of 10NiO/BaZrO ₃ :

Add 0.344 g ZrO(NO ₃ ) ₂ and 0.480 g Ba(NO ₃ ) ₂ to 12 mL of deionized water, stir for 25 min to make it evenly mixed, then add 0.041 g NiCl ₂ ·6H ₂ O, and then stir for 25 min to make the solution uniform. It is mixed evenly. Then, the mixed solution was added to 55 mL (12 mol/L) KOH solution, stirred vigorously for 30 min, and then charged into a 100 mL hydrothermal reactor with a polytetrafluoroethylene lining. The reaction kettle was placed in a 200 ^o C oven for 24 hours and taken out, cooled to room temperature naturally, and the product was washed with deionized water, glacial acetic acid and absolute ethanol for several times to remove excess alkali and carbonate impurities, and centrifuged. After drying, it was dried in an oven at 65 ^o C, and calcined in a muffle furnace at 450 ^o C for 3 h after being fully dried, and the obtained catalyst was marked as 10NiO/BaZrO ₃ .

Example 3

Preparation of 20NiO/BaZrO ₃ :

Add 0.455 g Zr(NO ₃ ) ₄ ·5H ₂ O and 0.480 g Ba(NO ₃ ) ₂ to 13 mL of deionized water, stir for 30 min to make it evenly mixed, then add 0.088 g NiSO ₄ ·6H ₂ O, and then Stir for 30 min to mix well. Then the mixed solution was added to 65 mL (15 mol/L) KOH solution, stirred vigorously for 50 min, and then charged into a 100 mL hydrothermal reactor with a Teflon lining. The reaction kettle was placed in a 200 ^o C oven for 24 hours and taken out, cooled to room temperature naturally, and the product was washed with deionized water, glacial acetic acid and absolute ethanol for several times to remove excess alkali and carbonate impurities, and centrifuged. After drying, it was dried in an oven at 75 ^o C, and calcined in a muffle furnace at 500 ℃ for 5 h after being fully dried, and the obtained catalyst was marked as 20NiO/BaZrO ₃ .

Example 4

Preparation of 30NiO/BaZrO ₃ :

Add 0.377 g ZrOCl ₂ ·8H ₂ O and 0.480 g Ba(NO ₃ ) ₂ to 15 mL of deionized water, stir for 40 min to make it evenly mixed, then add 0.146 g Ni(NO ₃ ) ₂ ·6H ₂ O, then Stir for 40 min to mix well. The mixed solution was then added to 70 mL (20 mol/L) KOH solution, stirred vigorously for 60 min, and then charged into a 100 mL hydrothermal reactor with a polytetrafluoroethylene lining. The reaction kettle was placed in a 200 ^o C oven for 24 hours and taken out, cooled to room temperature naturally, and the product was washed with deionized water, glacial acetic acid and absolute ethanol for several times to remove excess alkali and carbonate impurities, and centrifuged. After drying, it was dried in an oven at 80 ^o C, and calcined in a muffle furnace at 600 ^o C for 6 h after being fully dried, and the obtained catalyst was marked as 30NiO/BaZrO ₃ .

The above samples were tested by XRD on the X'Pert PRO MPD X-ray diffractometer of Panalytical Company in the Netherlands.

Figure 1 shows the XRD patterns of the barium zirconate supports and 10NiO/BaZrO ₃ , 20NiO/BaZrO ₃ and 30NiO/BaZrO ₃ catalysts prepared in Examples 1, 2, 3, and 4. Among the three samples, the characteristic diffraction peaks of barium zirconate did not change, indicating that barium zirconate remained stable during catalyst preparation and reduction. The diffraction peaks of NiO in the 10NiO/BaZrO ₃ sample are significantly smaller than those of other loading samples, indicating that the NiO grain size of 10NiO/BaZrO ₃ is smaller and the dispersion degree is higher.

Figure 2 is the SEM image of the 10NiO/BaZrO ₃ sample in Example 2. It can be seen that the morphology of the catalyst is hollow spherical.

Catalyst performance evaluation

Catalytic performance tests were carried out on Examples 2, 3 and 4. The catalytic stability of the prepared catalysts in the CO methanation reaction was tested. Put 500 mg of 20-40 mesh catalyst into a quartz reaction tube, pass it (flow rate: 30 mL/min) into a temperature-programmed reduction, and heat up at a rate of 2 °C/min. The reaction raw material gas was composed of H ₂ : CO: N ₂ volume flow rate ratio of 3:1:1, the reaction pressure was normal pressure, the mass space velocity was 60000 mL·h ^-1 ·g ^-1 , and the reaction temperature was 450 ℃.

Table 1 is the CO conversion rate and CH ₄ yield in the methanation reaction of the catalysts in Examples 2, 3 and 4

serial number CO conversion rate (%) CH₄ Yield (%) Example 2 90 85 Example 3 86 83 Example 4 82 81

It can be seen from Table 1 that the 10NiO/BaZrO ₃ methanation catalyst prepared in Example 2 has the best activity, with a CO conversion rate of 90% and a CH ₄ yield of 85%.

As mentioned above, the in-situ nickel-doped hollow barium zirconate CO methanation catalyst proposed by the present invention has high activity and has good application prospects in industrial applications.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention. Such changes and improvements fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (5)

1. a kind of hollow barium zirconate CO methanation catalyst of original position nickel doping, active component and carrier including catalyst.

2. a kind of hollow barium zirconate CO methanation catalyst of nickel doping in situ according to claim 1, which is characterized in that The catalyst activity component is nickel oxide；The catalyst carrier is barium zirconate；Wherein, catalyst activity component nickel oxide Weight percentage is respectively 10 ~ 30%, remaining to be divided into barium zirconate carrier.

3. a kind of hollow barium zirconate CO methanation catalyst of original position nickel doping, which is characterized in that carry out as follows:

Soluble zirconates and barium nitrate are added in deionized water, it is solvable that 20 ~ 40 min of stirring add it after mixing Property nickel salt, be followed by stirring for 20 ~ 40 min make its be uniformly mixed, then by mixed liquor be added to concentration be 10 ~ 20 mol/L hydrogen In potassium oxide solution, 100 mL are fitted into in the hydrothermal reaction kettle of polytetrafluoroethyllining lining after being vigorously stirred 30 ~ 60 min, are incited somebody to action Reaction kettle is placed in 200^oTaken out after reacting 24 h in C baking oven, cooled to room temperature, by product deionized water, glacial acetic acid and Dehydrated alcohol is washed to remove excessive alkali and carbonate impurities, after centrifuge separation, in 60 ~ 80^oIt is dry in C baking oven, it is sufficiently dry After dry 400 ~ 600 in Muffle furnace^oC calcines 2 ~ 6 h, and obtained catalyst is labeled as NiO/BaZrO₃。

4. a kind of hollow barium zirconate CO methanation catalyst of nickel doping in situ according to claim 3, which is characterized in that In the preparation method, soluble zirconates is zirconium oxychloride, zirconyl nitrate, zirconium nitrate.

5. a kind of hollow barium zirconate CO methanation catalyst of nickel doping in situ according to claim 3, which is characterized in that In the preparation method, soluble nickel salt is nickel acetate, nickel sulfate, nickel nitrate or nickel chloride.