CN115121255B - Preparation method of nickel-based catalyst, nickel-based catalyst and application of nickel-based catalyst - Google Patents

Abstract

The invention provides a preparation method of a nickel-based catalyst, the nickel-based catalyst and application thereof. The preparation method of the nickel-based catalyst comprises the following steps: 1) Ball milling is carried out on the mixture of silicon dioxide and Ni (NO ₃)₂·6H₂ O to obtain ball milling products; 2) Calcining the ball-milling product to obtain a catalyst precursor; 3) And (3) carrying out reduction treatment on the catalyst precursor to obtain the nickel-based catalyst. In the nickel-based catalyst prepared by the preparation method of the nickel-based catalyst, the density of the silicon dioxide carrier is high, and the dispersion degree of the nickel simple substance on the surface of the silicon dioxide carrier is high, so that the nickel-based catalyst has relatively excellent carbon deposition resistance and sintering resistance.

Description

A method for preparing a nickel-based catalyst, a nickel-based catalyst and its application

Technical Field

The invention relates to the technical field of environmental protection, and in particular to a preparation method of a nickel-based catalyst, a nickel-based catalyst and applications thereof.

Background technique

With the continuous increase of social demand, the global energy crisis and environmental crises such as the greenhouse effect are becoming increasingly serious. Therefore, it is urgent to find suitable renewable energy. At present, the use of biomass as a renewable energy source (biomass energy) is conducive to alleviating the global energy crisis and environmental crisis. Biomass gasification technology is one of the most promising methods for the utilization of biomass energy. Biomass gasification technology is a process in which solid fuels are converted into a combustible gas mixture through thermochemical reactions at high temperatures of 800-1000°C. This process mainly uses air, oxygen or water vapor as a gasifying agent. The thermochemical conversion of carbon-containing substances in biomass will produce non-condensable gases (such as carbon monoxide, carbon dioxide, a mixture of methane and hydrogen), volatile organic compounds (VOCs), tar, water vapor, _H2S , solid residues, high-carbon solid waste (coke), trace amounts of HCN, _NH3 and HCl. Among them, the formation of tar reduces the energy efficiency of the biomass gasification process, and tar will condense and concentrate under low temperature conditions, which can easily lead to blockage and pollution of downstream equipment. Therefore, the treatment of tar becomes a key issue that needs to be solved urgently in the biomass gasification process.

Tar is mainly composed of aromatic compounds, such as toluene, indene and naphthalene. At present, catalytic reforming is usually used to treat tar, that is, a catalyst is used to convert tar into useful gases ( _H2 , CO and _CH4 ) so that the tar can be removed. The use of catalysts in the catalytic reforming method can effectively reduce the reaction temperature, but in the catalytic reforming process, poisoning, sintering or carbon deposition of the catalyst can easily lead to rapid deactivation of the catalyst, thereby reducing the catalytic reforming efficiency of the tar or even ending the reforming process of the tar.

Therefore, it is necessary to develop catalysts that are resistant to carbon deposition and sintering.

Summary of the invention

The present invention provides a method for preparing a nickel-based catalyst. In the nickel-based catalyst obtained by the preparation method, a silica carrier has a high density, a nickel element has a high dispersion on the surface of the silica carrier, and has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance.

The present invention provides a nickel-based catalyst, which is prepared by the above-mentioned preparation method and thus has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance.

The present invention provides a method for treating tar, comprising using the above-mentioned nickel-based catalyst for catalytic treatment. The catalytic treatment has high efficiency and can convert more tar.

The present invention also provides a method for preparing a nickel-based catalyst, which comprises the following steps:

1) ball-milling a mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O to obtain a ball-milled product;

2) calcining the ball-milled product to obtain a calcined product;

3) washing the calcined product with an aqueous nitric acid solution to obtain a catalyst precursor;

4) performing a reduction treatment on the catalyst precursor to obtain the nickel-based catalyst.

The preparation method as described above, wherein the mass percentage of the metallic nickel is 0.3-0.6% based on the total mass of the ball-milled product; and/or,

The calcination treatment is carried out at a temperature of 1500-1800° C., at an air flow rate of 150-300 mL/min, and for a time of 5-7 h.

The preparation method as described above, wherein the reduction treatment is carried out using a mixed gas of hydrogen and argon;

Based on the total mass of the mixed gas, the volume percentage of the hydrogen is 3-5%.

The preparation method as described above, wherein the temperature of the reduction treatment is 500-650° C. and the time is 4-7 hours.

The present invention also provides a nickel-based catalyst, which is prepared by the preparation method as described above.

The present invention also provides a method for treating tar, which comprises using the nickel-based catalyst as described above to carry out catalytic treatment of the tar.

In the above-mentioned method for treating tar, the mesh size of the nickel-based catalyst is 40-60 meshes.

The tar treatment method as described above, wherein during the catalytic treatment process, it also includes introducing dielectric barrier discharge (DBD) plasma.

The tar treatment method as described above, wherein the discharge gap of the plasma is 2-3.5 mm; and/or,

The catalytic treatment time is 10-40 minutes.

The present invention provides a method for preparing a nickel-based catalyst. In the nickel-based catalyst obtained by the preparation method, a silica carrier has a high density and a nickel element has a high dispersion on the surface of the silica carrier. Therefore, the nickel-based catalyst has relatively excellent anti-carbon deposition and anti-poisoning capabilities, as well as anti-sintering performance, and is suitable for wide promotion and application.

The present invention provides a nickel-based catalyst, in which a silica carrier has a high density and a nickel element has a high dispersion on the surface of the silica carrier. Therefore, the nickel-based catalyst has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance, and is suitable for wide promotion and application.

The present invention provides a method for treating tar, comprising using the above-mentioned nickel-based catalyst for catalytic treatment. The catalytic treatment has high efficiency and can convert more tar.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present invention or related technologies. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a SEM image of a nickel-based catalyst A in the present invention;

FIG2 is a HAADF diagram of the nickel-based catalyst A of the present invention;

FIG. 3 is a SEM image of the nickel-based catalyst a in the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The first aspect of the present invention provides a method for preparing the above-mentioned nickel-based catalyst, which comprises the following steps:

1) ball-milling a mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O to obtain a ball-milled product;

2) calcining the ball-milled product to obtain a catalyst precursor;

3) The catalyst precursor is subjected to reduction treatment to obtain a nickel-based catalyst.

It can be understood that the preparation method of the nickel-based catalyst of the present invention specifically includes: 1) ball milling a mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O to make silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O more uniformly dispersed, to obtain a ball milling product in which silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O are uniformly dispersed;

2) calcining the ball-milled product in which silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O are uniformly dispersed in step 1) to convert Ni(NO ₃ ) ₂ ·6H ₂ O into nickel oxide and increase the density of silicon dioxide. After calcination, nickel oxide is loaded on the surface of the silicon dioxide carrier to form a catalyst precursor;

3) Performing a reduction treatment on a catalyst precursor containing nickel oxide to reduce the nickel oxide to nickel element. After the reduction treatment, the nickel element is loaded on the surface of the silica carrier to obtain the nickel-based catalyst of the present invention.

In the present invention, step 1) further comprises mixing silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O to obtain a mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O, and placing the mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O in a ball mill for ball milling to obtain a ball milled product. The present invention does not particularly limit silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O, and silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O commonly used in the art can be selected, for example, silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O can be obtained through commercial purchase. In some embodiments, the mass ratio of silicon dioxide to Ni(NO ₃ ) ₂ ·6H ₂ O is (8-10): (0.1-0.3), the rotation speed of the ball milling treatment is 400-550r/min, and the ball milling treatment time is 15h.

Step 2) also includes placing the ball-milled product in an alumina crucible and calcining it in an air atmosphere to obtain a catalyst precursor.

In some embodiments, step 2) further includes post-treatment, which includes washing the calcined product with a nitric acid aqueous solution to dissolve Ni(NO ₃ ) ₂ ·6H ₂ O that has not been completely converted into nickel oxide, and then placing the washed product in an oven at 80° for drying to obtain a washed product. In some embodiments, the concentration of the nitric acid aqueous solution is 0.4-0.7 mol/L, the washing temperature is room temperature, and stirring is also included during the washing process.

Furthermore, the post-treatment also includes grinding and sieving the cleaned product in sequence according to actual needs to obtain a catalyst precursor with a specific mesh size. In some embodiments, when the mesh size of the catalyst precursor is 40-60 mesh, it can be used for catalytic treatment of tar, and the catalytic treatment is efficient, and more tar can be converted and removed.

It will be appreciated that the mesh size of the catalyst precursor is comparable to the mesh size of the catalyst.

The method for preparing a nickel-based catalyst including the above steps can prepare a nickel-based catalyst with high silicon dioxide density and high nickel elemental dispersion. The nickel-based catalyst has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance, and is suitable for wide promotion and application.

In some embodiments of the present invention, the mass percentage of metallic nickel is 0.3-0.6% based on the total mass of the ball-milled product. When the mass percentage of metallic nickel in the ball-milled product meets the above range, it is more conducive to the dispersion of nickel on the surface of the silica carrier, improves the dispersibility of nickel, and further improves the catalytic activity of the nickel-based catalyst.

In the present invention, the parameters of the calcination treatment can be further selected to make the density of the silica carrier more excellent and to further improve the dispersibility of the nickel element on the surface of the silica carrier. In some embodiments of the present invention, the calcination treatment temperature is 1500-1800°C, the air flow rate is 150-300mL/min, and the time is 5-7h.

In some embodiments of the present invention, a mixture of hydrogen and argon is used for reduction treatment;

Based on the total mass of the mixed gas, the volume percentage of hydrogen is 3-5%.

It is understood that the hydrogen in the mixed gas is mainly used for reducing nickel oxide. In the present invention, the mixed gas is used for reduction treatment, which can better reduce nickel oxide to nickel element, and the raw material of the mixed gas is easy to obtain, which is conducive to saving production costs.

Furthermore, the temperature and time of the reduction treatment can be specifically selected in order to further reduce the nickel oxide to nickel element, increase the content of nickel element in the nickel-based catalyst, and further improve the catalytic efficiency of the nickel-based catalyst. In some embodiments of the present invention, the temperature of the reduction treatment is 500-650°C and the time is 4-7h.

The second aspect of the present invention provides a nickel-based catalyst, which is prepared by the above-mentioned preparation method.

The nickel-based catalyst of the present invention is prepared using the above-mentioned preparation method. Therefore, in the nickel-based catalyst, the density of the silica carrier is high, the dispersion of the nickel element on the surface of the silica carrier is high, and the nickel-based catalyst has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance, and is suitable for wide promotion and application.

The third aspect of the present invention provides a method for treating tar, which comprises catalytically treating tar using the above-mentioned nickel-based catalyst; or comprises catalytically treating tar using a nickel-based catalyst prepared by the above-mentioned method for preparing the nickel-based catalyst.

In the present invention, the above-mentioned nickel-based catalyst or the nickel-based catalyst prepared by the above-mentioned nickel-based catalyst preparation method is used to catalytically treat tar. Since the catalyst used has relatively excellent anti-poisoning ability, anti-carbon deposition and anti-sintering performance, the catalyst is not easy to be poisoned, carbonized or sintered during the catalytic treatment process, and the catalyst is not easy to be deactivated, which is conducive to improving the catalytic treatment efficiency of tar and converting more tar. Therefore, the tar treatment method of the present invention has a wide range of application prospects in the field of biomass gasification technology, and is conducive to alleviating environmental crises such as energy crisis and greenhouse effect.

In some embodiments of the present invention, during the treatment of tar, the mesh size of the nickel-based catalyst is 40-60 mesh, which can be more conducive to improving the catalytic treatment efficiency of tar and improving the removal rate of tar.

In some embodiments of the present invention, during the catalytic treatment, a dielectric barrier discharge (DBD) plasma is further introduced.

In the present invention, during the catalytic treatment process, dielectric barrier discharge (DBD) plasma is also introduced to couple the plasma with the nickel-based catalyst for catalytic treatment, which can further improve the efficiency of the catalytic treatment and remove more tar.

Furthermore, the discharge gap of the plasma can be limited, and the time of the catalytic treatment can be limited, in order to further improve the efficiency of the catalytic treatment and the removal rate of tar. In some embodiments of the present invention, the discharge gap of the plasma is 2-3.5 mm; and/or,

The catalytic treatment time is 10-40 minutes.

In some embodiments, the temperature of the catalytic treatment can be 200-450°C, and the mass volume ratio of the nickel-based catalyst to toluene is (0.5-1.3g):(0.5-0.7ml), the carrier gas flow rate during the catalytic treatment is 100mL/min, and the volume ratio of toluene to water is (1-3):(0.5-1.3).

The technical solution of the present invention will be further described below in conjunction with specific embodiments.

Example 1

The preparation method of the nickel-based catalyst A of this embodiment comprises:

1) 15 g SiO ₂ and 0.3735 g Ni(NO ₃ ) ₂ ·6H ₂ O were placed in a ball mill and continuously ball-milled for 15 h at a rotation speed of 450 r/min to obtain a ball-milled product;

Based on the total mass of the ball-milled product, the mass percentage of metallic nickel is 0.5wt%;

2) calcining the ball-milled product obtained in step 1) under air atmosphere;

The calcination time was 6 h, the calcination temperature was 1600 ° C, and the air flow rate was 200 mL/min;

3) washing the product obtained in step 2) with a 0.5 mol/L HNO ₃ aqueous solution to achieve a cleaning treatment of the product obtained in step 2), and drying the washed product in an oven at 80° C. for 12 h to obtain a dry product;

4) grinding and sieving the dried product obtained in 3) to obtain a powder of 40-60 mesh, i.e., a catalyst precursor;

5) using a mixture of hydrogen and argon to reduce the catalyst precursor obtained in step 4) to obtain a nickel-based catalyst A;

The temperature of the reduction treatment is 650° C., the volume percentage of hydrogen is 5% based on the total mass of the mixed gas, the flow rate of the mixed gas is 100 mL/min, and the reduction treatment time is 6 h.

The nickel-based catalyst A was subjected to SEM and HAADF tests, respectively. Figure 1 is a SEM image of the nickel-based catalyst A in the present invention, and Figure 2 is a HAADF image of the nickel-based catalyst A in the present invention. As shown in Figures 1 and 2, the surface density of the nickel-based catalyst A is high, and the dispersion of the nickel element is high.

The tar processing method of this embodiment includes:

The nickel-based catalyst A, simulated tar, dielectric barrier discharge (DBD) plasma and nitrogen are mixed to catalytically treat the simulated tar;

The catalytic treatment temperature was 300°C, the time was 30 min, the mass of the nickel-based catalyst A was 1 g, the nitrogen gas flow was 100 mL/min, the simulated tar included toluene and water, the volume of toluene was 0.63 mL, and the volume of water was 1.5 mL, and the plasma discharge gap was 2 mm.

Example 2

The preparation method of the nickel-based catalyst A of this embodiment comprises:

1) 15 g SiO ₂ and 0.3735 g Ni(NO ₃ ) ₂ ·6H ₂ O were placed in a ball mill and continuously ball-milled for 15 h at a rotation speed of 450 r/min to obtain a ball-milled product;

Based on the total mass of the ball-milled product, the mass percentage of metallic nickel is 0.5wt%;

2) calcining the ball-milled product obtained in step 1) under air atmosphere;

The calcination time was 6 h, the calcination temperature was 1600 ° C, and the air flow rate was 200 mL/min;

3) washing the product obtained in step 2) with a 0.5 mol/L HNO ₃ aqueous solution to achieve a cleaning treatment of the product obtained in step 2), and drying the washed product in an oven at 80° C. for 12 h to obtain a dry product;

4) grinding and sieving the dried product obtained in 3) to obtain a powder of 40-60 mesh, i.e., a catalyst precursor;

5) using a mixture of hydrogen and argon to reduce the catalyst precursor obtained in step 4) to obtain a nickel-based catalyst A;

The temperature of the reduction treatment is 650° C., the volume percentage of hydrogen is 5% based on the total mass of the mixed gas, the flow rate of the mixed gas is 100 mL/min, and the reduction treatment time is 6 h.

The nickel-based catalyst A was subjected to SEM and HAADF tests, respectively. Figure 1 is a SEM image of the nickel-based catalyst A in the present invention, and Figure 2 is a HAADF image of the nickel-based catalyst A in the present invention. As shown in Figures 1 and 2, the surface density of the nickel-based catalyst A is high, and the dispersion of the nickel element is high.

The tar processing method of this embodiment includes:

The nickel-based catalyst A, simulated tar, dielectric barrier discharge (DBD) plasma and nitrogen are mixed to catalytically treat the simulated tar;

The catalytic treatment temperature was 300°C, the time was 40 min, the mass of the nickel-based catalyst A was 1 g, the nitrogen gas flow was 100 mL/min, the simulated tar included toluene and water, the volume of toluene was 0.63 mL, and the volume of water was 1.5 mL, and the plasma discharge gap was 2 mm.

Comparative Example 1

The nickel-based catalyst a of this comparative example is prepared by a traditional impregnation method. In the nickel-based catalyst a (Ni/SiO ₂ ), the mass percentage of metal nickel is 2 wt %. The nickel-based catalyst a can be purchased commercially.

The nickel-based catalyst a was subjected to SEM testing, and Figure 3 is a SEM image of the nickel-based catalyst a in the present invention. As can be seen from Figure 3, the surface density of the nickel-based catalyst a is low, and the nickel element is agglomerated.

The tar treatment method of this comparative example is basically the same as that of Example 1, except that the nickel-based catalyst a is used to replace the nickel-based catalyst A in Example 1.

Comparative Example 2

The tar treatment method of this comparative example is basically the same as that of Example 1, except that the nickel-based catalyst A is not used.

Comparative Example 3

The tar treatment method of this comparative example is substantially the same as that of comparative example 1, except that plasma is not used.

Performance Testing

Liquid products were tested by automatic sampling using GC-MS (HRGC-LRMS, QP2020, Shimadzu, Japan), and the calculation formula was as follows:

The conversion rate of tar simulant is calculated by the following formula:

Where [T] _in is the number of moles of tar in the injected sample; [T] _out is the number of moles of tar in the liquid product.

Table 1

Toluene conversion rate/% Example 1 84.9 Example 2 84.5 Comparative Example 1 74 Comparative Example 2 63 Comparative Example 3 33.91

It can be seen from Table 1 that when the nickel-based catalyst in the embodiment of the present invention is used to treat tar, the conversion rate of tar is high.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. A method for preparing a nickel-based catalyst, characterized in that it comprises the following steps: 1) ball-milling a mixture of silicon dioxide and Ni(NO ₃ ) ₂ ·6H ₂ O at a rotation speed of 400-550 r/min to obtain a ball-milled product; wherein the mass percentage of metallic nickel is 0.3-0.6% based on the total mass of the ball-milled product; 2) calcining the ball-milled product at a temperature of 1500-1800° C., an air flow rate of 150-300 mL/min, and a time of 5-7 h to obtain a catalyst precursor; 3) using a mixture of hydrogen and argon to perform reduction treatment on the catalyst precursor for 4-7 hours to obtain the nickel-based catalyst; wherein the volume percentage of the hydrogen is 3-5% based on the total mass of the mixture. 2. The preparation method according to claim 1, characterized in that the temperature of the reduction treatment is 500-650°C. 3. A nickel-based catalyst, characterized in that it is prepared according to the preparation method according to claim 1 or 2. 4. A method for treating tar, characterized in that it comprises catalytic treatment of the tar using the nickel-based catalyst according to claim 3. 5. The method for treating tar according to claim 4, characterized in that the mesh number of the nickel-based catalyst is 40-60 mesh. 6. The tar treatment method according to claim 4 or 5, characterized in that during the catalytic treatment process, it also includes introducing dielectric barrier discharge plasma. 7. The tar treatment method according to claim 6, characterized in that the discharge gap of the plasma is 2-3.5 mm; and/or, The catalytic treatment time is 10-40 minutes.