Nickel-based catalyst and preparation method and use thereof

Abstract

A method for preparing a nickel-based catalyst. The method comprising firstly taking a mixed solution comprising a nickel salt, magnesium salt and an aluminium salt along with a sodium hydroxide solu

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of catalyst preparation, and in particular, to a nickel-based catalyst and a preparation method and use thereof. BACKGROUND

[0002] Dry reforming of CO2 and CH4 could generate a synthesis gas (including CO and H2) that can be used as raw materials for Fischer-Tropsch synthesis, which is an effective way to deal with the CO2 and CH4 serving as greenhouse gases. Storage and transportation of the synthesis gas (including CO and H?), as well as conversion in a downstream synthesizer, are all operated under high-pressure conditions. Therefore, it is highly necessary to operate the dry reforming of methane under high pressures to obtain a high-pressure synthesis gas, which is necessary for further conversion of the synthesis gas into other raw materials. However, on one hand, an equilibrium conversion rate of the dry reforming of methane decreases with an increasing pressure; and on the other hand, existing nickel-based catalysts are easily deactivated due to sintering and carbon deposition. Moreover, carbon deposit generated under high-pressure conditions is more serious than that under atmospheric pressure. SUMMARY

[0003] An object of the present disclosure is to provide a nickel-based catalyst and a preparation method and use thereof. In the present disclosure, the nickel-based catalyst shows desirable stability, strong anti-sintering ability, and strong anti-carbon deposition ability, and has high activity, excellent stability, and high equilibrium conversion rate when being applied to high-pressure dry reforming of methane.

[0004] To achieve the above object, the present disclosure provides the following technical solutions:

[0005] The present disclosure provides a method for preparing a nickel-based catalyst, including the following steps:

[0006] (1) simultaneously adding a mixed solution of a nickel salt, a magnesium salt and an aluminum salt, and a sodium hydroxide solution into a sodium carbonate solution, and subjecting a resulting mixture to coprecipitation and aging in sequence to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite;

[0007] (2) subjecting the magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) to calcination to obtain a nickel-magnesium-aluminum-containing oxide; and

[0008] (3) impregnating the nickel-magnesium-aluminum-containing oxide obtained in step (2) in a cerium salt solution, and subjecting a resulting material to secondary calcination to obtain the nickel-based catalyst.

[0009] In some embodiments, in step (1), a molar ratio of the nickel salt to the magnesium salt is in arange of 0.04:1 to0.17:l.

[0010] In some embodiments, in step (1), a molar ratio of the nickel salt to the aluminum salt is in a range of 0.12:1 to 0.39:1.

[0011] In some embodiments, in step (1), a molar ratio of the nickel salt to sodium carbonate in the sodium carbonate solution is in a range of 0.001:1 to 0.015:1.

[0012] In some embodiments, in step (1), the coprecipitation is conducted at a pH value of 9 to 9.5 for 1 h to 3 h.

[0013] In some embodiments, in step (2), the calcination is conducted at a temperature of 700 °C to 900 °C for 7 h to 9 h.

[0014] In some embodiments, a molar ratio of the nickel salt in step (1) to a cerium salt in the cerium salt solution in step (3) is in a range of 0.5:1 to 3.5:1.

[0015] In some embodiments, the secondary calcination in step (3) is conducted at a temperature of 700 °C to 900 °C for 3 h to 5 h.

[0016] The present disclosure further provides a nickel-based catalyst prepared by the method described above, including a nickel-magnesium-aluminum-containing oxide and cerium dioxide supported on a surface of the nickel-magnesium-aluminum-containing oxide.

[0017] The present disclosure further provides use of the nickel-based catalyst in production of a synthesis gas by high-pressure dry reforming of methane.

[0018] The present disclosure provides a method for preparing a nickel-based catalyst, including the following steps: (1) simultaneously adding a mixed solution of a nickel salt, a magnesium salt and an aluminum salt, and a sodium hydroxide solution into a sodium carbonate solution, and subjecting a resulting mixture to coprecipitation and aging to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite; (2) subjecting the magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) to calcination to obtain a nickel-magnesium-aluminum-containing oxide; and (3) impregnating the nickel-magnesium-aluminum-containing oxide obtained in step (2) in a cerium salt solution and conducting secondary calcination to obtain the nickel-based catalyst. In the present disclosure, a mixed solution of a nickel salt, a magnesium salt, and an aluminum salt, and a sodium hydroxide solution are simultaneously added into a sodium carbonate solution, such that Ni2+ reacts with CO A and Mg2+ and Al3+ react with OH to conduct coprecipitation to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite. Then, the magnesium-aluminum-nickel-carbonate hydrotalcite is subjected to aging to be more stable. Then, the magnesium-aluminum-nickel-carbonate hydrotalcite is subjected to calcination to make nickel be evenly distributed in a mixed metal oxide, forming a NiO-MgO solid solution with a strong interaction, thereby reducing a risk of sintering on nickel particles. Then, a resulting nickel-magnesium-aluminum-containing oxide is impregnated in a cerium salt solution, such that cerium is deposited on the nickel-magnesium-aluminum-containing oxide. Then, a resulting mixture is subjected to secondary calcination to form cerium dioxide particles on a surface of the nickel-magnesium-aluminum-containing oxide. This process is conducive to removing carbon deposits generated on a catalyst surface, and the cerium dioxide could also act as a physical barrier to inhibit the sintering of the nickel particles, thereby improving the stability of the catalyst in high-pressure dry reforming of methane. The results of examples show that the nickel-based catalyst according to the present disclosure has an equilibrium conversion rate of 73.4% for catalyzing methane conversion, a deactivation degree of 11.6% after 72 h of high-pressure dry reforming of methane, and a total carbon deposit of 93.8 mge gcat'1 after 72 h of high-pressure dry reforming of methane. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a carbon deposit amount of the nickel-based catalysts prepared in Examples 1 and 2 and Comparative Example 1 of the present disclosure after 72 h of high-pressure dry reforming of methane at 1.0 MPa;

[0020] FIG. 2 shows a transmission electron microscopy (TEM) image of the nickel-based catalyst prepared in Example 1 of the present disclosure after 72 h of high-pressure dry reforming of methane at 1.0 MPa;

[0021] FIG. 3 shows a TEM image of the nickel-based catalyst prepared in Example 2 of the present disclosure after 72 h of high-pressure dry reforming of methane at 1.0 MPa; and

[0022] FIG. 4 shows a TEM image of the nickel-based catalyst prepared in Comparative Example 1 of the present disclosure after 72 h of high-pressure dry reforming of methane at 1.0 MPa. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present disclosure provides a method for preparing a nickel-based catalyst, including the following steps:

[0024] (1) simultaneously adding a mixed solution of a nickel salt, a magnesium salt, and an aluminum salt, and a sodium hydroxide solution into a sodium carbonate solution, and subjecting a resulting mixture to coprecipitation and aging in sequence to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite;

[0025] (2) subjecting the magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) to calcination to obtain a nickel-magnesium-aluminum-containing oxide; and

[0026] (3) impregnating the nickel-magnesium-aluminum-containing oxide obtained in step (2) in a cerium salt solution, and subjecting a resulting material to secondary calcination to obtain the nickel-based catalyst.

[0027] In the present disclosure, a mixed solution of a nickel salt, a magnesium salt, and an aluminum salt, and a sodium hydroxide solution are simultaneously added into a sodium carbonate solution, and a resulting mixture is subjected to coprecipitation and aging in sequence to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite.

[0028] In the present disclosure, in some embodiments, the nickel salt is nickel nitrate hexahydrate. In some embodiments, the nickel salt in the mixed solution has a concentration of (0.01-0.03) mol-L4, and preferably 0.012 mol-L4. The concentration of the nickel salt is limited within the above range, which could ensure that the coprecipitation proceeds more fully.

[0029] In the present disclosure, in some embodiments, the magnesium salt is magnesium nitrate hexahydrate. In some embodiments, the magnesium salt in the mixed solution has a concentration of (0.1-0.3) mol L4, and preferably 0.14 mol L4. The concentration of the magnesium salt is limited within the above range, which could ensure that the coprecipitation proceeds more fully.

[0030] In the present disclosure, in some embodiments, the aluminum salt is aluminum nitrate nonahydrate. In some embodiments, the aluminum salt in the mixed solution has a concentration of (0.02-0.06) molL4, and preferably 0.04 molL4. The concentration of the aluminum salt is limited within the above range, which could ensure that the coprecipitation proceeds more fully.

[0031] In the present disclosure, in some embodiments, a molar ratio of the nickel salt to the magnesium salt is in a range of 0.04:1 to 0.17:1, and preferably 0.08:1 to 0.15:1. The molar ratio of the nickel salt to the magnesium salt is limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is better obtained.

[0032] In the present disclosure, in some embodiments, a molar ratio of the nickel salt to the aluminum salt is in a range of 0.12:1 to 0.39:1, and preferably 0.2:1 to 0.3:1. The molar ratio of the nickel salt to the aluminum salt is limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is better obtained.

[0033] In the present disclosure, in some embodiments, the sodium hydroxide solution has a concentration of (1.5-2) mol L4. In some embodiments, a molar ratio of the nickel salt to sodium hydroxide in the sodium hydroxide solution is in a range of 0.001:1 to 0.006:1, and preferably 0.003:1. The dosage of the sodium hydroxide is limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is better obtained.

[0034] In the present disclosure, in some embodiments, the sodium carbonate solution has a concentration of (1.5-2) mol-L4. In some embodiments, a molar ratio of the nickel salt to sodium carbonate in the sodium carbonate solution is in a range of 0.001:1 to 0.015:1, and preferably 0.005:1 to 0.01:1. The dosage of the sodium carbonate is limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is better obtained.

[0035] In the present disclosure, in some embodiments, the mixed solution of the nickel salt, the magnesium salt, and the aluminum salt and the sodium hydroxide solution are stirred when being added into the sodium carbonate solution. In some embodiments, the stirring is conducted at a speed of 250 r / min to 350 r / min. In the present disclosure, in some embodiments, the mixed solution of the nickel salt, the magnesium salt, and the aluminum salt and the sodium hydroxide solution are added dropwise into the sodium carbonate solution. In the present disclosure, the adding dropwise is conducted at a speed of (1.0-2.5) mL-min4, and preferably 2 mL min4. The way and speed of the adding dropwise are limited within the above range, which could ensure that the coprecipitation is more fully completed.

[0036] In the present disclosure, during the coprecipitation, Ni2+ reacts with COs2', and Mg’ and Al3+ reacts with OH' to conduct the coprecipitation to obtain the magnesium-aluminum-nickel-carbonate hydrotalcite. In the present disclosure, in some embodiments, the coprecipitation is conducted under a pH value of 9 to 9.5. In the present disclosure, in some embodiments, the coprecipitation is conducted at a temperature of 50 °C to 80 °C for 1 h to 3 h. The pH value and time of the coprecipitation are limited within the above range, which could ensure that the coprecipitation can be conducted more fully.

[0037] In the present disclosure, in some embodiments, the aging is conducted at a temperature of 100 °C to 150 °C, and preferably 120 °C. In some embodiments, the aging is conducted for 1 d to 3 d. The temperature and time of the aging are limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is generated more stably.

[0038] In the present disclosure, in some embodiments, after the aging is completed, a resulting product is subjected to washing with deionized water, suction filtration, drying, and grinding in sequence to obtain the magnesium-aluminum-nickel-carbonate hydrotalcite.

[0039] In the present disclosure, in some embodiments, the washing with deionized water is conducted until an aging precipitate is neutral. There is no particular limitation on the suction filtration, and any suction filtration method known in the art may be used.

[0040] In the present disclosure, in some embodiments, the drying is conducted at a temperature of 100 °C to 150 °C, and preferably 130 °C. In some embodiments, the drying is conducted for 10 h to 50 h, and preferably 20 h to 40 h. The temperature and time of the drying are limited within the above range, which could ensure that the magnesium-aluminum-nickel-carbonate hydrotalcite is fully dried.

[0041] In the present disclosure, in some embodiments, the magnesium-aluminum-nickel-carbonate hydrotalcite has a particle size of 1 nm to 20 nm, and preferably 3 nm to 8 nm. There is no particular limitation on a grinding method, and any grinding method known in the art may be used.

[0042] In the present disclosure, after the magnesium-aluminum-nickel-carbonate hydrotalcite is obtained, the magnesium-aluminum-nickel-carbonate hydrotalcite is subjected to calcination to obtain a nickel-magnesium-aluminum-containing oxide.

[0043] In the present disclosure, in some embodiments, the calcination is conducted at a temperature of 700 °C to 900 °C, and preferably 800 °C. In some embodiments, the calcination is conducted for 7 h to 9 h. The temperature and time of the calcination are limited in the above range, which could make the nickel be uniformly distributed in a mixed metal oxide, forming a NiO-MgO solid solution with a strong interaction, thereby reducing a risk of sintering on nickel particles.

[0044] In the present disclosure, in some embodiments, after the calcination is completed, a resulting calcination product is naturally cooled to ambient temperature to obtain a nickel-mixed oxide.

[0045] In the present disclosure, after the nickel-mixed oxide is obtained, the nickel-magnesium-aluminum-containing oxide is impregnated in a cerium salt solution and a resulting material is then subjected to secondary calcination to obtain the nickel-based catalyst.

[0046] In the present disclosure, in some embodiments, a cerium salt in the cerium salt solution is cerium nitrate hexahydrate. In the present disclosure, in some embodiments, the cerium salt has a concentration of (0.05-0.35) molL’1, and preferably (0.06-0.13) molL’1. In the present disclosure, in some embodiments, a molar ratio of the nickel salt to the cerium salt in the cerium salt solution is in a range of 0.5:1 to 3.5:1, and preferably 1:1 to 2:1. The concentration and dosage of the cerium salt are limited within the above range, which could ensure better deposition of the cerium salt into the mixed metal oxide.

[0047] In the present disclosure, in some embodiments, the impregnating is conducted at a temperature of 70 °C to 90 °C. In the present disclosure, in some embodiments, the impregnating is conducted for 5 h to 10 h, and preferably 8 h. The time and temperature of the impregnating are limited within the above range, which could ensure better deposition of the cerium salt into the nickel-magnesium-aluminum-containing oxide.

[0048] In the present disclosure, in some embodiments, after the impregnating is completed, a resulting impregnated product is dried. In some embodiments, the drying is conducted at a temperature of 100 °C to 150 °C, and preferably 130 °C. In some embodiments, the drying is conducted for 10 h to 30 h, and preferably 15 h to 20 h. The temperature and time of the drying are limited within the above range, which could ensure more complete drying.

[0049] In the present disclosure, in some embodiments, the secondary calcination is conducted at a temperature of 700 °C to 900 °C, and preferably 800 °C. In some embodiments, the secondary calcination is conducted for 3 h to 5 h. The temperature and time of the secondary calcination are limited within the above range, which could better form cerium dioxide particles on the surface of the nickel-magnesium-aluminum-containing oxide, which is conducive to removing the carbon deposits generated on the catalyst surface during the reaction. Meanwhile, the cerium dioxide could also act as a physical barrier to inhibit the sintering of nickel particles, thereby improving the stability of the catalyst in high-pressure dry reforming of methane.

[0050] In the present disclosure, in some embodiments, after the secondary calcination is completed, a resulting secondary calcination product is subjected to tabletting and granulation to obtain the nickel-based catalyst.

[0051] In the present disclosure, in some embodiments, the nickel-based catalyst has a particle size of 40 mesh to 60 mesh. There is no particular limitation on the methods of tabletting and granulation, any tabletting and granulation methods well known in the art may be used.

[0052] In the present disclosure, a mixed solution of a nickel salt, a magnesium salt, and an aluminum salt, and a sodium hydroxide solution are simultaneously added into a sodium carbonate solution, such that Ni2+ reacts with CO32’ and Mg2+ and Al3+ react with OIT to conduct coprecipitation to obtain the magnesium-aluminum-nickel-carbonate hydrotalcite. Then, the magnesium-aluminum-nickel-carbonate hydrotalcite is subjected to aging to be more stable. Then, the magnesium-aluminum-nickel-carbonate hydrotalcite is subjected to calcination to make nickel be evenly distributed in a mixed metal oxide, forming a NiO-MgO solid solution with a strong interaction, thereby reducing a risk of sintering on nickel particles. Then, a resulting nickel-magnesium-aluminum-containing oxide is impregnated in a cerium salt solution, such that cerium is deposited on the nickel-magnesium-aluminum-containing oxide. Then, a resulting material is subjected to secondary calcination to form cerium dioxide particles on a surface of the nickel-magnesium-aluminum-containing oxide. This process is conducive to removing carbon deposits generated on a catalyst surface, and the cerium dioxide could also act as a physical barrier to inhibit the sintering of the nickel particles, thereby improving a stability of the catalyst in high-pressure dry reforming of methane.

[0053] The present disclosure further provides a nickel-based catalyst prepared by the method described above, including a nickel-magnesium-aluminum-containing oxide and cerium dioxide supported on a surface of the nickel-magnesium-aluminum-containing oxide.

[0054] In the present disclosure, the nickel-based catalyst shows desirable stability, strong anti-sintering ability, and strong anti-carbon deposition ability, and has high activity, excellent stability, and high equilibrium conversion rate when being applied to high-pressure dry reforming of methane.

[0055] The present disclosure further provides use of the nickel-based catalyst prepared by the method described above in production of a synthesis gas by high-pressure dry reforming of methane.

[0056] In the present disclosure, in some embodiments, the nickel-based catalyst has a dosage of 0.1 g to 1.0 g, and preferably 0.2 g to 0.5 g.

[0057] In the present disclosure, in some embodiments, the synthesis gas is produced by the high-pressure dry reforming of methane under a pressure of 1.0 MPa to 5.0 MPa, and preferably 3.0 MPa.

[0058] In the present disclosure, in some embodiments, the synthesis gas is produced by the high-pressure dry reforming of methane at a temperature of 650 °C to 950 °C, and preferably 850 °C. In some embodiments, the synthesis gas is produced by the high-pressure dry reforming of methane at a space velocity of (50,000-100,000) mL goat^ h'1.

[0059] In the present disclosure, the nickel-based catalyst has high activity, desirable stability, and excellent equilibrium conversion rate in the production of synthesis gas by high-pressure dry reforming of methane.

[0060] The technical solutions of the present disclosure will be clearly and completely described below with reference to the examples of the present disclosure. Apparently, the described embodiments are merely some rather than all of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative efforts shall fall within the scope of the present disclosure.

[0061] Example 1

[0062] A method of a nickel-based catalyst was performed as follows:

[0063] (1) A mixed solution of 0.012 molL'1 nickel nitrate hexahydrate, 0.14 molL'1 magnesium nitrate hexahydrate, and 0.04 mol L'1 aluminum nitrate nonahydrate and a 2.0 mol L'1 sodium hydroxide solution were simultaneously added dropwise into a 2 mol L'1 sodium carbonate solution at 2.0 mL min’1. A resulting mixture was subjected to coprecipitation at 60 °C under 300 r / min for 1 h. Then, a resulting material was subjected to aging in an oven at 100 °C for 1 d. Then, a resulting material was washed with deionized water until neutral, and then subjected to suction filtration to obtain magnesium-aluminum-nickel-carbonate hydrotalcite. Where a molar ratio of the nickel nitrate hexahydrate to the magnesium nitrate hexahydrate was 0.08:1, a molar ratio of the nickel nitrate hexahydrate to the aluminum nitrate nonahydrate was 0.12:1, a molar ratio of the nickel nitrate hexahydrate to the sodium hydroxide was 0.006:1, and a molar ratio of the nickel nitrate hexahydrate to the sodium carbonate was 0.006:1.

[0064] (2) The magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) was subjected to drying at 100 °C for 1 d. Then, a resulting material was ground into a powder, and the powder was subjected to calcination at 800 °C for 8 h. Then, a resulting material was cooled to ambient temperature to obtain a nickel-magnesium-aluminum-containing oxide.

[0065] (3) The nickel-magnesium-aluminum-containing oxide obtained in step (2) was impregnated in a 0.08 mol L'1 cerium nitrate hexahydrate solution at 70 °C for 7 h. Then, a resulting material was dried at 100 °C for 24 h. Then a resulting material was subjected to secondary calcination at 700 °C for 4 h. Then, a resulting material was subjected to tabletting and granulation to obtain the nickel-based catalyst with a particle size of 40 mesh to 60 mesh, recorded as NiCei / MgAl(O); where a molar ratio of the nickel nitrate hexahydrate to the cerium nitrate hexahydrate was 1:1.

[0066] Example 2

[0067] Example 2 was performed according to Example 1, except that a molar ratio of the nickel nitrate hexahydrate to the cerium nitrate hexahydrate was 1:2, so as to obtain a nickel-based catalyst, recorded as NiCe2 / MgAl(O).

[0068] Comparative Example 1

[0069] Comparative Example 1 was performed according to Example 1, except that the cerium nitrate hexahydrate was not added, so as to obtain a nickel-based catalyst, recorded as Ni / MgAl(0).

[0070] In the present disclosure, the stability of the nickel-based catalysts prepared in Example 1, Example 2 and Comparative Example 1 was determined. Specifically, the stability evaluation of the nickel-based catalyst was conducted in a homemade fixed bed reactor: the reactor was divided into an external stainless steel tube (8 mm) and an internal quartz tube (5 mm), and a mixture of 0.3 g of the nickel-based catalyst (40 mesh to 60 mesh) and 0.7 g of quartz sand was loaded in a middle of the quartz reactor. The reactor was under a pressure of 1.0 MPa, and then a sample in the reactor was heated from ambient temperature to 900 °C at l°C / min in H2 / N2 atmosphere (20 mL / min, 1:1), and in-situ reduced at 900 °C for 2 h. After the temperature dropped to 850 °C, 75 mL / min of CH4 and 75 mL / min of CO2 were added as raw gas, and a space velocity was 60,000 mL gcat^ h’1. An outlet gas was analyzed using a gas chromatograph (HaixinGC-950) with a TCD detector to calculate conversion rates of CH4 and CO2 and a deactivation degree of the catalyst. A conversion rate curve of CH4 and CO2 catalyzed by the nickel-based catalyst within 72 h and the conversion rates of CH4 and CO2 and the deactivation degree of the nickel-based catalyst are shown in Table 1.

[0071] A calculation formula of the deactivation degree is: deactivation degree=(initial conversion rate of CH4 - conversion rate of CH4 after 72 h) / initial conversion rate of CH4X100%

[0072] Table 1 Conversion rate and deactivation degree of CH4

[0073] Initial conversion rate Conversion rate of Deactivation ofCH4(%) CH4 after 72 h (%) degree (%) Example 1 65.45 57.42 12.26 Example 2 66.54 58.82 11.60 Comparative Example 1 68.63 46.65 32.02

[0074] As shown in Table 1: the nickel-based catalysts prepared in Examples 1 and 2 of the present disclosure have a catalyst deactivation rate much lower than that of the nickel-based catalyst prepared in Comparative Example 1 after high-pressure dry reforming of methane under 1.0 MPa at 850 °C for 72 h, indicating that the catalyst for high-pressure dry reforming of methane shows excellent stability.

[0075] In the present disclosure, the carbon deposit amount of the nickel-based catalysts prepared in Examples 1 and 2 and Comparative Example 1 is tested by O2-TPO-MS characterization experiment using a TP-5080 programmed adsorption instrument. 100 mg of a reacted catalyst was loaded into a quartz tube microreactor and purged with pure He gas at a constant temperature of 150 °C for 30 min. After cooling to 50°C, the pure He gas was switched to a mixed gas of 5% 02 / 95% Ar and maintained for 30 min. Then, the temperature was increased from 50 °C to 900 °C, and temperature-programmed oxidation (with a heating rate of 10 °C / min) was performed. The exhaust gas was detected by HIDEN (QIC-20) mass spectrometer to obtain the relationship curve between CO2 signal and temperature, so as to determine the type of carbon species and calculate the carbon deposit amount based on activated carbon. The carbon deposit amount and the total carbon deposit amount before and after 600 °C in the heating stage were calculated, and the results were shown in FIG. 1 and Table 2, respectively.

[0076] Table 2 Carbon deposit amounts of nickel-based catalysts prepared in Example 1, Example 2 and Comparative Example 1

[0077] Total carbon deposit amount (mgegcaf1) Carbon deposit less than 600 °C (mgegcaf1) Carbon deposit greater than 600 °C (mge-gcaf1) Example 1 198.3 151.7 46.6 Example 2 93.8 72.3 40.9 Comparative Example 1 530.5 73.5 457.0

[0078] As shown in FIG. 1 and Table 2: after 72 h of high-pressure dry reforming of methane under 1.0 MPa at 850 °C, the carbon deposit amount on the surface of the nickel-based catalysts prepared in Example 1 and Example 2 of the present disclosure is much lower than that of the nickel-based catalyst prepared in the comparative example, and there is no peak above 650 °C. Since the carbon deposit not greater than 600 °C is easier to remove and has less impact on the catalyst, indicating that the nickel-based catalyst has an excellent anti-carbon deposition ability.

[0079] In the present disclosure, the morphologies of the nickel-based catalysts prepared in Example 1 and Example 2 and the nickel-based catalyst prepared in Comparative Example 1 after high-pressure dry reforming of methane under 1.0 MPa at 850 °C for 72 h are characterized by TEM, and the results are shown in FIG. 2 to FIG. 4, respectively. From the figures, it can be seen that, only ordinary graphite carbon is observed on the surface of the nickel-based catalyst of the present disclosure and no encapsulated graphite carbon is observed, while encapsulated graphite carbon could be observed on the surface of the nickel-based catalyst prepared in Comparative Example 1. It is indicated that the nickel-based catalyst could remove most of the encapsulated graphite carbon and has higher activity when being applied to high-pressure dry reforming of methane.

[0080] In summary, the nickel-based catalyst prepared by the present disclosure shows desirable stability, strong anti-sintering ability, and strong anti-carbon deposition ability, and has high activity, excellent stability, and high equilibrium conversion rate when being applied to high-pressure dry reforming of methane.

[0081] The above descriptions are merely preferred embodiments of the present disclosure. It should be noted that those skilled in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should be deemed as falling within the scope of the present disclosure. WHAT IS CLAIMED IS: 1. A method for preparing a nickel-based catalyst, comprising the following steps: (1) simultaneously adding a mixed solution of a nickel salt, a magnesium salt and an aluminum salt, and a sodium hydroxide solution into a sodium carbonate solution, and subjecting a resulting mixture to coprecipitation and aging in sequence to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite; (2) subjecting the magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) to calcination to obtain a nickel-magnesium-aluminum-containing oxide; and (3) impregnating the nickel-magnesium-aluminum-containing oxide obtained in step (2) in a cerium salt solution, and subjecting a resulting material to secondary calcination to obtain the nickel-based catalyst. 2. The method of claim 1, wherein in step (1), a molar ratio of the nickel salt to the magnesium salt is in a range of 0.04:1 to 0.17:1. 3. The method of claim 1 or 2, wherein in step (1), a molar ratio of the nickel salt to the aluminum salt is in a range of 0.12:1 to 0.39:1. 4. The method of claim 1, wherein in step (1), a molar ratio of the nickel salt to sodium carbonate in the sodium carbonate solution is in a range of 0.001:1 to 0.015:1. 5. The method of claim 1, wherein in step (1), the coprecipitation is conducted at a pH value of 9 to 9.5 for 1 h to 3 h. 6. The method of claim 1, wherein in step (2), the calcination is conducted at a temperature of 700 °C to 900 °C for 7 h to 9 h. 7. The method of claim 1, wherein a molar ratio of the nickel salt in step (1) to a cerium salt in the cerium salt solution in step (3) is in a range of 0.5:1 to 3.5:1. 8. The method of claim 1, wherein in step (3), the secondary calcination is conducted at a temperature of 700 °C to 900 °C for 3 h to 5 h. 9. A nickel-based catalyst prepared by the method of any one of claims 1 to 8, comprising a nickel-magnesium-aluminum-containing oxide and cerium dioxide supported on a surface of the nickel-magnesium-aluminum-containing oxide. 10. Use of the nickel-based catalyst of claim 9 in production of a synthesis gas by high-pressure dry reforming of methane. 03 07 25 Amendments to the claims have been filed as follows:

Claims

1. A method for preparing a nickel-based catalyst, comprising the following steps:(1) simultaneously adding a mixed solution of a nickel salt, a magnesium salt and an aluminum salt, and a sodium hydroxide solution into a sodium carbonate solution, and subjecting a resulting mixture to coprecipitation and aging in sequence to obtain a magnesium-aluminum-nickel-carbonate hydrotalcite;(2) subjecting the magnesium-aluminum-nickel-carbonate hydrotalcite obtained in step (1) to calcination to obtain a nickel-magnesium-aluminum-containing oxide; and(3) impregnating the nickel-magnesium-aluminum-containing oxide obtained in step (2) in a cerium salt solution, and subjecting a resulting material to secondary calcination to obtain the nickel-based catalyst;wherein the coprecipitation in step (1) is conducted at a pH value of 9 to 9.5 and a temperature of 50 °C to 80 °C for 1 h to 3 h; andthe aging in step (1) is conducted at a temperature of 100 °C to 150 °C for 1 d to 3 d.

2. The method of claim 1, wherein in step (1), a molar ratio of the nickel salt to the magnesium salt is in a range of 0.04:1 to 0.17:1.

3. The method of claim 1 or 2, wherein in step (1), a molar ratio of the nickel salt to the aluminum salt is in a range of 0.12:1 to 0.39:1.

4. The method of claim 1, wherein in step (1), a molar ratio of the nickel salt to sodium carbonate in the sodium carbonate solution is in a range of 0.001:1 to 0.015:1.

5. The method of claim 1, wherein in step (2), the calcination is conducted at a temperature of 700 °C to 900 °C for 7 h to 9 h.

6. The method of claim 1, wherein a molar ratio of the nickel salt in step (1) to a cerium salt in the cerium salt solution in step (3) is in a range of 0.5:1 to 3.5:1.

7. The method of claim 1, wherein in step (3), the secondary calcination is conducted at a temperature of 700 °C to 900 °C for 3 h to 5 h.LDCM

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