CN108636412A - Methane and carbon dioxide reforms the preparation method of multinuclear shell hollow type catalyst nickel-nisiloy hydrochlorate - Google Patents

Abstract

The invention discloses a method for preparing nickel-nickel silicate, a multi-core-shell hollow catalyst for reforming methane and carbon dioxide. The method includes the steps of: (1) mixing ethanol, water, and a silicon source under the condition of 0 ^o C to 70 ^o C Stir evenly, adjust the pH to 7-10, react for 8-13 hours, centrifuge, wash, and finally dry at 50 ^o C ~ 400 ^o C to obtain silica nanoparticles with a particle size of 100nm ~ 1µm; (2) in aqueous solution Add silica nanoparticles to make the concentration of 1g/L～10g/L, add lye, adjust the pH to 8～13, add nickel precursor with a concentration of 1g/L～10g/L, at a temperature of 50 ^o C ~ 220 ^o C, react for 5 ^~ 72 ^hours , and then process the nickel silicate hollow sphere; Inject hydrogen for reduction to prepare a multi-core-shell hollow catalyst nickel-nickel silicate. The multi-core-shell hollow catalyst nickel-nickel silicate prepared by the invention has a relatively high nickel loading capacity, and simultaneously has high anti-sintering and anti-carbon deposition properties.

Description

Preparation of nickel-nickel silicate as multi-core-shell hollow catalyst for methane and carbon dioxide reforming preparation method

technical field

The invention relates to a method for preparing nickel-nickel silicate, a multi-core-shell hollow catalyst for reforming methane and carbon dioxide, and belongs to the technical field of chemical production.

Background technique

Nickel-based catalysts have been extensively studied at home and abroad because of their low cost and high catalytic activity for reforming. When it is applied to the reforming reaction of _CH4 and _CO2 , the carbon deposition phenomenon of nickel-based catalysts is relatively serious, mainly because the sintering of nickel metal will promote the occurrence of carbon deposition side reactions, especially when the loading of nickel is relatively high, The sintering phenomenon is more obvious and the carbon deposition is more serious. The inventors of the present invention have developed core-shell structure catalysts, which can inhibit the sintering of active metals. However, they generally have the problem of low mass transfer efficiency.

At the same time, metallosilicates are widely used as catalysts because of their low price, high temperature stability, and high specific surface area. However, these metallosilicates are only used as catalyst precursors at present, and these metallosilicate precursors are completely decomposed after high-temperature reduction, losing their advantages of high specific surface area. Additionally, the loading of these catalysts is less than 20 wt%.

Namely: There is a need for a _CH4 and _CO2 catalyst with high resistance to sintering and carbon deposition at higher loadings.

Contents of the invention

The technical problem to be solved in the present invention is to provide a method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate, so that _CH4 and _CO2 reforming catalysts have high resistance to sintering under relatively high loads And anti-carbon performance, can overcome the deficiencies of the prior art.

The technical solution of the present invention is: a method for preparing nickel-nickel silicate as a multi-core-shell hollow catalyst for reforming methane and carbon dioxide. The method includes the following steps: (1) under the condition of 0 ^o C ~ 70 ^o C, Mix and stir ethanol, water and silicon source evenly, then add lye to adjust the pH to 7-10, react for 8-13 hours, separate and wash with a centrifuge, and finally dry at 50 ^o C ~ 400 ^o C to obtain carbon dioxide Silicon nanoparticles; (2) Add silica nanoparticles to the aqueous solution to make the concentration 1g/L-10g/L, add lye, adjust the pH to 8-13, and add the concentration to 1g/L-10g/L Nickel precursors, reacted at a temperature of 50 ^o C to 220 ^o C for 5 to 72 hours, cooled, centrifuged, washed, and dried to obtain nickel silicate hollow spheres; (3) Nickel silicate The salt hollow spheres are reduced by passing hydrogen gas under the condition of reduction temperature of 300 ^o C ~ 800 ^o C, and the multi-core-shell hollow catalyst nickel-nickel silicate is prepared.

In the above step (1), the silicon source is one or a combination of ethyl orthosilicate, sodium silicate water glass, and methyl orthosilicate.

In the above step (2), the nickel precursor is one or a combination of nickel nitrate, nickel acetate, nickel acetylacetonate, nickel oxalate, and nickel oleate.

In the above steps (1) and (2), the lye is one or a combination of sodium hydroxide, urea, and ammonia water.

In the above steps (1) and (2), the washing solvent used for washing is one or a combination of water, ethanol, methanol, acetone, and cyclohexane.

In the aforementioned step (3), the specific surface area of the prepared nickel-nickel silicate is 200m ² ·g ^-1 ~ 400m ² ·g ^-1 , the loading is 30wt% ~ 40wt%, and the particle size of nickel is 2nm ~10nm.

Compared with the prior art, the preparation method of nickel-nickel silicate, a multi-core-shell hollow catalyst for methane and carbon dioxide reforming in the present invention, includes the following steps: (1) under the condition of 0 ^o C ~ 70 ^o C, ethanol , water and silicon source are mixed and stirred evenly, then add lye to adjust the pH to 7-10, react for 8-13 hours, separate and wash with a centrifuge, and finally dry at 50 ^o C ~ 400 ^o C to obtain silica nano (2) Add silica nanoparticles to the aqueous solution to make the concentration 1g/L-10g/L, add lye, adjust the pH to 8-13, and add nickel with a concentration of 1g/L-10g/L The precursor is reacted at a temperature of 50 ^o C to 220 ^o C for 5 to 72 hours, cooled, centrifuged, washed, and dried to obtain nickel silicate hollow spheres; (3) hollow nickel silicate Under the condition of reduction temperature of 300 ^o C ~ 800 ^o C, the sphere is reduced by feeding hydrogen gas to prepare a multi-core-shell hollow catalyst nickel-nickel silicate. After many tests, the multi-core-shell hollow catalyst nickel-nickel silicate prepared by this method has the following characteristics: at a reaction temperature of 700 ^o C, it has high anti-carbon deposition performance, and the carbon deposition content is less than 5%; As high as 30wt% to 40wt%, it has obvious advantages over conventional catalysts with a load of less than 20wt%; high dispersion (particle size 2nm to 10nm), high specific surface area (200m ² ·g ^-1 ~ 400m ² ·g ^-1 ), with high mass transfer efficiency. Nickel nanoparticles are dispersed in nickel silicate hollow spheres to form a core-shell hollow structure with a particle size of 500nm to 1µm. Compared with existing _CH4 and _CO2 dry reforming nickel-based catalysts, the synthesis method of the present application is rapid, the synthetic raw materials are easy to get, and can realize large-scale synthesis, and the synthesized catalyst has high specific surface area, high loading capacity, and high dispersion. High mass transfer efficiency, good anti-carbon performance.

Description of drawings

Fig. 1 is a schematic diagram of the preparation method of nickel-nickel silicate as a multi-core-shell hollow catalyst.

Figure 2 is a transmission electron microscope image of a nickel silicate hollow sphere.

Figure 3 is a high-resolution transmission electron microscope image of a nickel silicate hollow sphere.

Fig. 4 is a transmission electron microscope image of a multi-core-shell hollow catalyst nickel-nickel silicate.

Fig. 5 is a high-resolution transmission electron microscope image of the multi-core-shell hollow catalyst nickel-nickel silicate.

Fig. 6 is the X-ray diffraction pattern of nickel silicate hollow sphere and multi-core shell hollow catalyst nickel-nickel silicate.

Figure 7 is a diagram of the reforming activity of nickel-nickel silicate CH ₄ and CO ₂ reforming with multiple core-shell hollow catalysts.

Fig. 8 is the thermogravimetric and thermal difference analysis diagram of nickel-nickel silicate CH ₄ and CO ₂ reforming reaction of multi-core-shell hollow catalyst.

Detailed ways

A method for preparing nickel-nickel silicate as a multi-core-shell hollow catalyst for reforming methane and carbon dioxide, the method includes the following steps: (1) under the condition of 0 ^o C ~ 70 ^o C, ethanol, water and silicon source Mix and stir evenly, then add lye to adjust the pH to 7-10, react for 8-13 hours, separate and wash with a centrifuge, and finally dry at 50 ^o C ~ 400 ^o C to obtain the carbon dioxide with a particle size of 100nm ~ 1μm Silicon nanoparticles; (2) Add silica nanoparticles to the aqueous solution to make the concentration 1g/L-10g/L, add lye, adjust the pH to 8-13, and add the concentration to 1g/L-10g/L Nickel precursors, reacted at a temperature of 50 ^o C to 220 ^o C for 5 to 72 hours, cooled, centrifuged, washed, and dried to obtain nickel silicate hollow spheres; (3) Nickel silicate The salt hollow spheres are reduced by passing hydrogen gas under the condition of reduction temperature of 300 ^o C ~ 800 ^o C, and the multi-core-shell hollow catalyst nickel-nickel silicate is prepared.

Example 1

(1) 200mL of ethanol, 100mL of water and 40mL of methyl orthosilicate were mixed and stirred evenly at 0 ^o C, and the pH was adjusted to 10 by adding urea. After stirring for 2 hours, it was separated with a centrifuge, and then washed with a mixture of methanol and water. Finally, 600nm silica nanoparticles were obtained and dried at 150 ^o C for 24h.

(2) Take 2g of silicon dioxide and 0.3g of nickel nitrate with a particle size of 500nm, add ammonia water, and adjust the pH to 8. The mixed solution was put into an autoclave, heated to 50 ^o C, reacted for 24 hours, and cooled to room temperature. Centrifuge, wash with methanol, ethanol, and water, and place in a 100-degree drying oven. Obtain nickel silicate hollow spheres (as shown in Figures 2, 3, and 6). The specific area is 250m ² ·g ^-1 , and the nickel loading is 30wt%.

(3) Put the nickel silicate hollow spheres into a muffle furnace for calcination at 300 ^o C for 4 hours, then pass through pure hydrogen, and reduce them at 300 ^o C for 0.5 hours to finally obtain the multi-core-shell hollow catalyst nickel-nickel silicate (As shown in Figure 4, 5, 6). It can be seen from Figures 4, 5, and 6 that the acicular nickel silicate phase still exists after high-temperature calcination and reduction. It can be seen that in the catalyst obtained by this synthesis method, the nickel silicate is not completely decomposed, and the particle size of the highly dispersed nickel is about 5nm. Under normal pressure, pass CH ₄ , CO ₂ and He in a 1:1:1 manner (space velocity 36L·g ^-1 cat·h ^-1 ), pass through the multi-core-shell hollow catalyst nickel-nickel silicate to immobilize Bed reactor (700 ^o C), after 70 h of reaction, the conversion of methane and carbon dioxide remained stable at 77.5% and 86.6% (Fig. 7). Thermogravimetric differential thermal analysis shows that the weight loss is less than 5%, indicating that the catalyst has a high ability to resist carbon deposition (Figure 8).

Example 2

(1) 200mL of ethanol, 100mL of water and 10mL of sodium silicate were mixed and stirred evenly at room temperature, and then ammonia water was added to adjust the pH to 10. After stirring for 2 hours, it was separated with a centrifuge, and then washed with a mixture of ethanol and water. Finally, 200nm silica nanoparticles were obtained and dried at 150°C for 24h.

(2) Take silicon dioxide with a particle size of 750nm, 0.3g of nickel acetate, add ammonia water, and adjust the pH to 12. Put the mixed solution into an autoclave, heat to 120°C, react for 24 hours, and then cool to room temperature. Centrifuge, wash with methanol, ethanol, and water, and place in a 100 ^o C drying oven. A nickel silicate hollow sphere was obtained with a specific area of 230m ² ·g ^-1 and a nickel loading of 40wt%.

(3) Put the nickel silicate hollow spheres into a muffle furnace for calcination at 550 ^o C for 4 hours, then pass through pure hydrogen, and reduce at 550 ^o C for 0.5 hours, and finally obtain the multi-core shell hollow catalyst nickel-nickel silicate . After high temperature calcination and reduction, the acicular nickel silicate phase still exists. It can be seen that in the catalyst obtained by this synthesis method, the nickel silicate is not completely decomposed, and the particle size of the highly dispersed nickel is about 7nm.

Example 3

(1) 200mL of ethanol, 100mL of water and 10mL of sodium silicate were mixed and stirred evenly at 70 ^o C, and the pH was adjusted to 10 by adding ammonia water. After stirring for 12 hours, it was separated with a centrifuge, and then washed with ethanol and water. Finally, 1 µm silica nanoparticles were obtained and dried at 150°C for 24 hours.

(2) Take 2g of silicon dioxide with a particle size of 1µm, 0.3g of nickel acetylacetonate, add sodium hydroxide, and adjust the pH to 13. Put the mixed solution into a high-pressure reactor, heat it to 220 ^o C, react for 24 hours, cool to room temperature, centrifuge, wash with methanol, ethanol, and water, put it into a 100-degree drying oven, and after drying, you can get A nickel silicate hollow sphere with a specific area of 328m ² ·g ^-1 and a nickel loading of 35wt%.

(3) Put the nickel silicate hollow spheres into the muffle furnace for calcination at 800 ^o C for 4 hours, then pass through 5% hydrogen, and reduce them at 800 ^o C for 0.5 hours, and finally obtain the multi-core shell hollow catalyst nickel-nickel silicon salt. After high temperature calcination and reduction, the acicular nickel silicate phase still exists. It can be seen that the catalyst obtained by this synthesis method, the nickel silicate is not completely decomposed. The particle size of highly dispersed nickel is about 6nm.

Example 4

(1) 200mL of ethanol, 100mL of water and 40mL of methyl orthosilicate were mixed and stirred evenly at room temperature, and urea was added to adjust the pH to 10. After stirring for 2 hours, it was separated with a centrifuge, and then washed with a mixture of methanol and water. Finally, 600nm silica nanoparticles were obtained and dried at 150 ^o C for 24h.

(2) Take 2g of silicon dioxide and 0.3g of nickel nitrate, add ammonia water, and adjust the pH to 12. Put the mixed solution into an autoclave, heat to 120°C, react for 24 hours, and then cool to room temperature. Centrifuge, wash with methanol, ethanol, and water, and put it into a 100-degree drying oven. Obtain nickel silicate hollow spheres (as shown in Figures 2, 3, and 6). The specific area is 250m ² ·g ^-1 , and the nickel loading is 30wt%.

(3) Put the nickel silicate hollow spheres into a muffle furnace and calcinate at 700 degrees for 4 hours. Then pass through pure hydrogen and reduce at 700 degrees for 0.5h. Finally, a multi-core-shell hollow catalyst nickel-nickel silicate is obtained (as shown in Figures 4, 5, and 6). It can be seen from Figures 4, 5, and 6 that the acicular nickel silicate phase still exists after high-temperature calcination and reduction. It can be seen that in the catalyst obtained by this synthesis method, the nickel silicate is not completely decomposed, and the particle size of the highly dispersed nickel is about 5nm. Under normal pressure, pass CH ₄ , CO ₂ and He in a 1:1:1 manner (space velocity 36L·g ^-1 cat·h ^-1 ), pass through the multi-core-shell hollow catalyst nickel-nickel silicate to immobilize Bed reactor (700 ^o C), react for 70h. The conversions of methane and carbon dioxide remained stable at 77.5% and 86.6% (Fig. 7). Thermogravimetric differential thermal analysis shows that the weight loss is less than 5%, indicating that the catalyst has a high ability to resist carbon deposition (Figure 8).

Example 5

(1) Mix 200mL ethanol, 100mL water and 10mL sodium silicate at 0 ^o C and stir evenly. Aqueous ammonia was added to adjust the pH to 10. After stirring for 2 hours, it was separated with a centrifuge, and then washed with a mixture of ethanol and water. Finally, 200nm silica nanoparticles were obtained and dried at 150°C for 24h.

(2) Take 2g of silicon dioxide, 0.3g of nickel acetate, add ammonia water, and adjust the pH to 12. Put the mixed solution into an autoclave, heat to 120°C, react for 24 hours, and then cool to room temperature. Centrifuge, wash with methanol, ethanol, and water, and put in a 100 ^o C drying oven. A nickel silicate hollow sphere was obtained with a specific area of 230m ² ·g ^-1 and a nickel loading of 40wt%.

(3) Put the nickel silicate hollow spheres into a muffle furnace for calcination at 700°C for 4h, then pass pure hydrogen into it, and reduce at 700°C for 0.5h to finally obtain the multi-core-shell hollow catalyst nickel-nickel silicate. After high temperature calcination and reduction, the acicular nickel silicate phase still exists. It can be seen that in the catalyst obtained by this synthesis method, the nickel silicate is not completely decomposed, and the particle size of the highly dispersed nickel is about 7nm.

Example 6

(1) 200mL of ethanol, 100mL of water and 10mL of sodium silicate were mixed and stirred evenly at room temperature, and ammonia water was added to adjust the pH to 10. After stirring for 12 hours, the mixture was separated by a centrifuge, and then washed with ethanol and water. Finally, 1 µm silica nanoparticles were obtained and dried at 150°C for 24 hours.

(2) Take 2g of silicon dioxide, 0.3g of nickel acetylacetonate, add sodium hydroxide, and adjust the pH to 12. Put the mixed solution into an autoclave, heat to 120°C, react for 24 hours, and then cool to room temperature. Centrifuge, wash with methanol, ethanol, and water, and put it into a 100-degree drying oven. A nickel silicate hollow sphere is obtained. The specific area is 328m ² ·g ^-1 , and the nickel loading is 35wt%.

(3) Put the nickel silicate hollow spheres into a muffle furnace and calcinate at 700 degrees for 4 hours. Then, 5% hydrogen gas was introduced, and the reduction was carried out at 700 degrees for 0.5h, and the multi-core-shell hollow catalyst nickel-nickel silicate was finally obtained. Although the acicular nickel silicate phase still exists after high-temperature calcination and reduction, it can be seen that the nickel silicate is not completely decomposed in the catalyst obtained by the synthesis method. The particle size of highly dispersed nickel is about 6nm.

Claims (7)

1. the preparation method of methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate, is characterized in that, the method comprises the following steps: (1) Mix and stir ethanol, water and silicon source at 0 ^o C ~ 70 ^o C, then add lye to adjust the pH to 7 ~ 10, react for 8 ~ 13 hours, separate and wash with a centrifuge, Finally, dry at 50 ^o C ~ 400 ^o C to obtain silica nanoparticles; (2) Add silica nanoparticles to the aqueous solution to make the concentration 1g/L-10g/L, add lye, adjust the pH to 8-13, and add nickel precursor with a concentration of 1g/L-10g/L , react at a temperature of 50 ^o C to 220 ^o C for 5 to 72 hours, then cool, centrifuge, wash, and dry to obtain nickel silicate hollow spheres; (3) Under the condition of reduction temperature of 300 ^o C ~ 800 ^o C, the nickel silicate hollow spheres are passed through hydrogen for reduction, and the multi-core-shell hollow catalyst nickel-nickel silicate is prepared. 2. The method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate according to claim 1, characterized in that: in step (1), the silicon source is ethyl orthosilicate, One or a combination of sodium silicate water glass, orthomethyl silicate. 3. The method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate according to claim 1, characterized in that: in the step (1), the prepared silica nanoparticles The diameter is 100nm ~ 1µm. 4. The method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate according to claim 1, characterized in that: in step (2), the nickel precursor is nickel nitrate, nickel acetate , nickel acetylacetonate, nickel oxalate, nickel oleate or a combination of several. 5. The method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate according to claim 1, characterized in that: in the steps (1) and (2), the lye is hydroxide One or a combination of sodium, urea, and ammonia water. 6. The method for preparing methane and carbon dioxide reforming multi-core-shell hollow catalyst nickel-nickel silicate according to claim 1, characterized in that: in the steps (1) and (2), the washing solvent used for washing is One or a combination of water, ethanol, methanol, acetone, cyclohexane. 7. The method for preparing nickel-nickel silicate as a multi-core-shell hollow catalyst for reforming methane and carbon dioxide according to claim 1, characterized in that: in step (3), the ratio of the prepared nickel-nickel silicate The surface area is between 200m ² ·g ^-1 and 400m ² ·g ^-1 , the loading is between 30wt% and 40wt%, and the particle size of nickel is between 2nm and 10nm.