CN113134356A

CN113134356A - Aluminum-based MOFs-derived Ni-based catalyst, preparation method and application in CO methanation reaction

Info

Publication number: CN113134356A
Application number: CN202110449816.2A
Authority: CN
Inventors: 王红; 张二桐; 王晓燕; 包亚莉; 吴俊霞; 纪利春
Original assignee: Inner Mongolia University of Technology
Current assignee: Inner Mongolia University of Technology
Priority date: 2021-04-25
Filing date: 2021-04-25
Publication date: 2021-07-20
Anticipated expiration: 2041-04-25
Also published as: CN113134356B

Abstract

The invention relates to an aluminum-based MOFs-derived Ni-based catalyst, a preparation method and its use in CO methanation reaction. The precursor of the catalyst is composed of a carrier and a nickel component, wherein the carrier is NiAl ₂ O ₄ with a porosity of 45-55% and a microporous and mesoporous structure derived from MOF-Al. The total content of Ni is 5wt% to 20wt%. The catalyst can realize the progressive reduction of NiO through controllable reduction, and is used in the methanation reaction of syngas. The catalyst of the present invention can be used in a wide reaction temperature range, and can meet the requirements of activity and thermal stability at low temperature and high temperature at the same time. The catalyst of the present invention also improves the utilization rate of the active metal Ni during the use of the catalyst, and the active metal particles of the catalyst of the present invention are not easy to aggregate, and it is not easy to cause the catalyst to be deactivated by sintering.

Description

Aluminum-based MOFs-derived Ni-based catalyst, preparation method and application in CO methanation reaction

Technical Field

The invention relates to an aluminum-based MOFs-derived Ni-based catalyst, a preparation method thereof and application thereof in CO methanation reaction.

Background

In the technical fields of heterogeneous catalysis technology and composite materials, synthesis gas methanation is a key technology of coal-based natural gas, at present, a coal-based natural gas methanation catalyst (technology) is mainly provided by foreign companies such as David in the United kingdom, Topyol in Denmark and the like, but the catalyst for obtaining industrial application still has the problems of low-temperature activity, easy carbon deposition, easy sintering of high-temperature active components and the like which need to be solved. Only the normal pressure partial methanation technology for producing the urban gas and trace CO/CO in China₂The methanation catalyst for purifying the gas has no catalyst for industrial application in the methanation section of the process for preparing the natural gas from the coal.

The CO methanation reaction is a strong exothermic and volume-reduced reaction, and the temperature of a reaction system rises to 73 ℃ every time 1% of CO is converted, which requires that the CO methanation catalyst has a wide reaction temperature range, a low activation temperature and good high thermal stability.

The CO methanation catalyst is usually Al₂O₃Is used as a carrier, NiO is used as an active component. And catalytically active is NiO reduced Ni⁰At different reduction temperatures, the reduced Ni⁰Comprises alpha type (reduction of NiO with weak action of carrier at a reduction temperature of less than 400 ℃), beta type (reduction of NiO with strong action of carrier at a reduction temperature of 400-700 ℃) and gamma type Ni⁰(NiAl₂O₄At a temperature of more than 700 ℃), wherein the alpha-form Ni⁰Is a key component for keeping the activation temperature low, beta type Ni⁰Is a key component for maintaining the activity of the medium temperature, namely gamma-type Ni⁰Is a key component for maintaining high thermal stability. The reduction state of the active component is closely related to the catalyst structure, and at present, most catalysts are reduced only in a certain narrow temperature range. For example, patent CN106582655A discloses the preparation of a high-dispersion easy-to-reduce supported nickel-aluminum catalyst, which requires reduction at 550 ℃ for 2 h.Patent CN111068643A discloses a CO&CO₂And (3) preparing a co-methanation catalyst, wherein the catalyst is reduced for 2 hours at the temperature of 350-450 ℃. The patent CN104549291A discloses a preparation method of a nickel-aluminum catalyst, wherein the reduction temperature is 700-750 ℃, and the reduction time is 1-2 h. No matter the reduction temperature of the catalysts is high or low, the reduced active metal can not meet the requirements of activity and thermal stability at low temperature and high temperature.

The traditional nickel-aluminum catalyst formed by high-temperature roasting has high reduction difficulty, the reduction temperature is too concentrated, and most of the nickel-aluminum catalyst is concentrated in a high-temperature area, so that the utilization rate of active metal Ni is reduced, the active metal particles of the catalyst are easily gathered, and the catalyst is sintered and inactivated.

At present, no report that a Ni-based catalyst derived from aluminum-based MOFs (Metal organic Frameworks) can be controllably reduced to realize progressive reduction of NiO and is used for methanation reaction of synthesis gas is found in the existing report.

Disclosure of Invention

Problems to be solved by the invention

The invention aims to solve the technical problems that the CO methanation catalyst in the prior art can only be reduced at a certain temperature, and the reduced active metal can not meet the requirements of activity and thermal stability at low temperature and high temperature no matter the reduction temperature of the catalyst is high or low.

The invention also aims to solve the technical problems that the traditional nickel-aluminum catalyst formed by high-temperature roasting has higher reduction difficulty, the reduction temperature is too concentrated, the utilization rate of active metal Ni is reduced in a high-temperature area, and the agglomeration of active metal particles of the catalyst is easily caused to cause the sintering inactivation of the catalyst.

Means for solving the problems

In order to solve the technical problems in the prior art, the invention provides the following technical scheme:

1. an aluminum-based MOFs-derived Ni-based catalyst characterized by: the precursor of the catalyst consists of a carrier and nickel componentsWherein the carrier is NiAl which is derived from MOF-Al and has a micropore and mesoporous structure with the porosity of 45-55 percent₂O₄The total content of Ni in the precursor is 5 wt% -20 wt%.

2. The aluminum-based MOFs-derived Ni-based catalyst according to item 1, wherein after the precursor is reduced at a temperature of 400-650 ℃ in a hydrogen atmosphere, the nickel component is alpha-type Ni as an active component⁰And beta form Ni⁰Are present.

3. The aluminum-based MOFs-derived Ni-based catalyst according to item 2, wherein the NiAl is present in a reaction atmosphere at a reaction temperature of 700-900 ℃ in a synthesis gas CO hydrogenation reaction₂O₄The nickel in the nickel is reduced into an active component gamma-type Ni⁰。

4. The Al-based MOFs-derived Ni-based catalyst according to item 2, wherein said Ni is in the alpha form⁰Is 5-10%, beta type Ni⁰The content of (a) is 25-35% based on the total mass of Ni in the catalyst.

5. The aluminum-based MOFs-derived Ni-based catalyst according to item 3, wherein gamma-type Ni is added at the reaction temperature of 700-900 DEG C⁰The content of (a) is 50-60% based on the total mass of Ni in the catalyst.

6. A method for preparing the aluminum-based MOFs-derived Ni-based catalyst according to any one of items 1 to 5, comprising the steps of:

step 1: preparing a metal organic framework (MOF-Al) carrier by using soluble aluminum salt, dicarboxylic acid and water;

step 2: soaking the metal organic framework carrier MOF-Al in a mixed solution of soluble nickel salt and alcohol, and then roasting to prepare a catalyst precursor NiO/NiAl₂O₄；

And step 3: NiO/NiAl as the catalyst precursor₂O₄Reducing in hydrogen atmosphere to obtain the aluminum-based MOFs-derived Ni-based catalyst.

7. The method for preparing the aluminum-based MOFs-derived Ni-based catalyst according to item 6, wherein the molar ratio of the soluble aluminum salt to the dicarboxylic acid is 1:10 to 10:1, preferably 3:1 to 1: 3; more preferably 2: 1.

8. The preparation method of the aluminum-based MOFs-derived Ni-based catalyst according to the item 6 or 7, characterized in that the reaction temperature in the step (1) is 200-300 ℃, and the reaction time is 60-100 h.

9. The preparation method of the aluminum-based MOFs-derived Ni-based catalyst according to any one of the claims 6 to 8, characterized in that the roasting temperature in the step (2) is 850-950 ℃, preferably 875-900 ℃, and the roasting time is 1-4 hours, preferably 2-3 hours.

10. The method for preparing the Al-based MOFs-derived Ni-based catalyst according to any one of the claims 6 to 9, wherein the temperature of the reduction in the step (3) is 500 ℃ to 700 ℃, preferably 600 ℃; the reduction time is 1-3 h, preferably 1.5-2 h.

11. Use of an aluminium-based MOFs-derived Ni-based catalyst according to item 1 in the methanation of synthesis gas CO.

ADVANTAGEOUS EFFECTS OF INVENTION

Compared with the prior art, the invention has the following beneficial effects.

The invention provides an aluminum-based MOFs-derived Ni-based catalyst, which can realize the progressive reduction of NiO through controllable reduction and is used for the methanation reaction of synthesis gas. The catalyst of the invention can be used in a wide range of reaction temperature and can simultaneously meet the requirements of activity and thermal stability at low temperature and high temperature. The catalyst of the invention also improves the utilization rate of active metal Ni during the use period of the catalyst, and the active metal particles of the catalyst are not easy to aggregate, thereby being not easy to cause sintering deactivation of the catalyst.

Drawings

FIG. 1 is an X-ray diffraction pattern of a sample of catalyst Ni/Al-1 before and after methanation of syngas.

FIG. 2 shows NiO/NiAl catalyst precursors according to the invention₂O₄H of (A) to (B)₂-a TPR map.

FIG. 3 is a TEM image of the catalyst of the present invention.

FIG. 4 is a graph showing activity test of the catalyst of the present invention.

FIG. 5 is a graph showing stability tests of the catalyst of the present invention.

Detailed Description

The invention carries out detailed research aiming at the problems that the prior Ni-based catalyst has low-temperature activity, and active components are easy to sinter at high temperature, and the like. Researches show that the Ni-based catalyst in the prior art is alpha-type Ni due to the strong exothermic reaction of CO methanation when applied to a catalyst for CO methanation reaction⁰And beta form Ni⁰The catalyst is easy to aggregate and deactivate in the reaction process to lose catalytic activity, but the catalyst can only be applied in a single narrow reaction temperature range, cannot have activity in a wide reaction temperature range, and the use efficiency of the catalyst is reduced due to the aggregation of active components. For example, in the methanation reaction of CO, alpha-type Ni is added at the reaction temperature of less than 400 DEG C⁰Is used as main active component, and when the reaction temperature is 400-700 deg.C, the beta-type Ni⁰Is a main active component, and in the actual reaction process, bed heat cannot be removed in time due to strong heat release of the methanation reaction of CO, and the actual bed temperature is higher than the reaction temperature by more than 200 ℃ along with the extension of the reaction time, which leads to alpha-type Ni⁰And beta form Ni⁰Aggregation deactivation occurs, but Ni is not reduced due to the absence of new active component⁰And supplementing, so that the catalytic activity is remarkably reduced. The aluminum-based MOFs-derived Ni-based catalyst carrier prepared by the invention contains NiAl₂O₄A component which reduces gamma-type Ni in a reaction atmosphere⁰This is the main active component at high reaction temperature and is the main reason why the catalyst can ensure high temperature activity and stability. The temperature of a CO methanation reaction bed layer is usually within the range of 200-900 ℃, which requires that a catalyst has high and low temperature activity and high thermal stability at the same time, and a Ni-based catalyst which can maintain high and low temperature activity and realize high thermal stability on one catalyst is not found at present, which is also a main problem in actual industrial production.

MOFs are short for Metal organic Frameworks (Metal organic Frameworks). The material is a crystalline porous material with a periodic network structure formed by connecting an inorganic metal center (metal ion or metal cluster) and a bridged organic ligand through self-assembly.

Through the intensive research of the invention, the aluminum-based MOFs-derived Ni-based catalyst has higher catalytic activity at 200-900 ℃ when applied to the CO methanation reaction, and the catalytic mechanism is presumed as follows:

the prepared aluminum-based MOFs-derived Ni-based catalyst has rich mesoporous and microporous structures, and Ni in the precursor of the prepared aluminum-based MOFs-derived Ni-based catalyst is converted into NiO and NiAl through dynamic phase transformation among nickel and aluminum in the roasting process in the preparation process₂O₄The two structural forms coexist, the molar ratio of the two structural forms is controlled within a certain range, the aluminum-based MOFs-derived Ni-based catalyst is prepared after the reduction at the temperature of 600 ℃, and the catalyst active component of the obtained aluminum-based MOFs-derived Ni-based catalyst is beta-type Ni⁰Mainly accounting for 20-40 percent, and a small amount of alpha-type Ni⁰About 5-10% of the total amount of NiAl₂O₄And the phase accounts for about 30-70%.

In the process of CO methanation reaction, when reduction is carried out under the condition that the reduction condition is 500-650 ℃, the active component alpha-type Ni in the aluminum-based MOFs-derived Ni-based catalyst⁰Is 5-10%, beta type Ni⁰The content of the Ni-based catalyst is 20-40%, so that the aluminum-based MOFs-derived Ni-based catalyst has good catalytic activity in low and medium temperature (less than 700 ℃) environments.

Furthermore, as the temperature of the CO methanation reaction bed layer is further increased, the mesoporous and microporous structures of the aluminum-based MOFs-derived Ni-based catalyst are further collapsed, and NiAl₂O₄Phase is exposed on the surface and reduced to generate gamma-type Ni in the reaction process⁰For example, NiAl is added to the catalyst in the reaction atmosphere when the reaction temperature is raised to more than 700 ℃ to 900 DEG C₂O₄Reduction of nickel in the form to gamma-form Ni⁰Gamma type Ni⁰The content of the Ni-based catalyst can reach 30-70%, so that the aluminum-based MOFs-derived Ni-based catalyst has good catalytic activity at the high temperature of 700-900 ℃.

In addition, the catalyst precursor NiO/NiAl₂O₄The dynamic phase transformation of each component can be generated in the roasting process.

According to the aluminum-based MOFs-derived Ni-based catalyst, along with the change of temperature, all components can generate dynamic phase transition, and the progressive reduction of NiO is realized, so that the aluminum-based MOFs-derived Ni-based catalyst realizes two-step progressive reduction of the catalyst in a reducing atmosphere and a reaction atmosphere, and ensures that the catalyst has enough active sites continuously in a wide reaction temperature range (200-900 ℃), and the catalyst simultaneously keeps good low-temperature activity and high thermal stability.

According to the aluminum-based MOFs-derived Ni-based catalyst, a precursor of the aluminum-based MOFs-derived Ni-based catalyst, called a catalyst precursor for short, is composed of a carrier and a nickel component, wherein the carrier is MOF-Al-derived NiAl with a micropore and mesoporous structure with porosity of 40-55%₂O₄The total content of Ni in the precursor is 5 wt% -20 wt%.

The porosity is preferably 40-55%; more preferably 50%; particularly preferably 55%.

The total content of Ni in the precursor is preferably 8-15%; more preferably 10% to 12%.

In the preparation process of the aluminum-based MOFs-derived Ni-based catalyst, the reduction temperature is 500-650 ℃, preferably 550-650 ℃, more preferably 550-625 ℃, particularly preferably 600 ℃, and the reduction time is 1-3 hours, preferably 1.5-2.5 hours, more preferably 2 hours.

Said aluminum-based MOFs-derived Ni-based catalyst, alpha-Ni⁰The content of (a) is 5-10%, preferably 6-9%; more preferably 7-9%; particularly preferably 8%, based on the total mass of Ni in the catalyst.

Beta type Ni⁰The content of (a) is 20-40%, preferably 25-35%; more preferably 27-30%; particularly preferably 30%, based on the total mass of Ni in the catalyst.

The aluminum-based MOFs-derived Ni-based catalyst is prepared by adding NiAl into the catalyst in the atmosphere of CO methanation reaction at the temperature of more than 700-900 DEG C₂O₄Reduction of nickel in the form to gamma-form Ni⁰Gamma type Ni⁰The content of (a) is 30-60%, preferably 45-55%; more preferably 45-50%; particularly preferably 45%, based on the total mass of Ni in the catalyst.

The aluminum-based MOFs-derived Ni-based catalyst is prepared by the following method, and the preparation method comprises the following steps:

step 2: soaking the metal organic framework carrier MOF-Al in a mixed solution of soluble nickel salt and alcohol, and then roasting to prepare a catalyst precursor NiO/NiAl₂O₄，

Examples of the soluble aluminum salt include: aluminum nitrate nonahydrate, aluminum trichloride, aluminum sulfate, and the like, but are not limited thereto.

Examples of the dicarboxylic acids include: aliphatic hydrocarbon dicarboxylic acids, malonic acid, succinic acid, azelaic acid (AZA), sebacic acid, and the like; aromatic hydrocarbon dicarboxylic acids, isophthalic acid (IPA), terephthalic acid (IPA), and the like, but are not limited thereto.

Examples of the alcohol include: methanol, ethanol, propanol, isopropanol, and the like, but is not limited thereto.

The molar ratio of the soluble aluminum salt to the dicarboxylic acid is 1: 10-10: 1, preferably 1: 3-3: 1; more preferably 2: 1.

The soluble nickel salt comprises: nickel sulfate, nickel chloride, nickel bromide, nickel iodide, sodium nitrate, nickel acetate, and the like, but is not limited thereto.

The reaction temperature in the step (1) is 200-300 ℃, preferably 230-280 ℃, and more preferably 220 ℃.

The reaction time is 40-100 h, preferably 60-80 h, and further preferably 50-60 h.

The NiO/MOF-Al impregnated in the step 2 can undergo dynamic phase transition in the roasting process to form NiO/NiAl₂O₄。

In the step (2), the roasting temperature is 850-950 ℃, preferably 900 ℃, and the roasting time is 1-4 hours, preferably 3 hours.

The reduction temperature in the step (3) is 500-650 ℃, preferably 600 ℃, and the reduction time is 1-3 hours, preferably 2 hours.

Examples

The aluminum-based MOFs-derived Ni-based catalysts provided by the present invention will be illustrated below by way of examples, but the scope of protection of the present invention is not limited by the following examples.

Example 1

Preparation of aluminum-based MOFs

First, 15g of aluminum nitrate nonahydrate (Al (NO) was weighed₃)₃·9H₂O) and 4g of organic ligand (terephthalic acid) were dispersed in deionized water. The above solution was transferred to a 100mL stainless steel reactor lined with teflon, sealed and placed in an oven at 200 ℃ for 72 h. After the reaction, the temperature is slowly reduced to room temperature, the sample is transferred to a beaker, repeatedly washed by distilled water and filtered, and then is put into an oven at 80 ℃ for overnight drying. And after drying, washing with DMF at room temperature, stirring for 8h, performing suction filtration with absolute ethyl alcohol, and drying in an oven at 120 ℃ for 12h to obtain the product MIL-53 (Al).

Preparation of aluminum-based MOFs-derived Ni-based catalysts

10mL of ethanol was added to a 100mL beaker, and 0.24g of nickel nitrate was weighed and stirred with a glass rod until completely dissolved (dark green). Then, 2g of MIL-53(Al) was weighed out and added to the above solution, stirred for 2 hours and allowed to stand at room temperature overnight. The resulting sample was dried in an oven at 120 ℃ for 12 h. Heating to 900 ℃ at the heating rate of 2 ℃/min in the air atmosphere, and roasting for 3h to obtain the catalyst precursor NiO/NiAl₂O₄The porosity is 45%, the Ni load is 10 wt%, and finally the catalyst is reduced in hydrogen atmosphere at 600 ℃ to finally prepare the aluminum-based MOFs-derived Ni-based catalyst, namely the catalyst Ni/Al-1.

Example 2

A catalyst precursor NiO/NiAl was prepared in the same manner as in example 1, except that 0.36g of nickel nitrate was weighed out₂O₄The porosity is 48%, the Ni load is 15 wt%, and finally the catalyst is reduced in hydrogen atmosphere at 600 ℃ to finally prepare the aluminum-based MOFs-derived Ni-based catalyst, namely the catalyst Ni/Al-2.

Example 3

A catalyst precursor NiO/NiAl was prepared in the same manner as in example 1, except that the temperature was raised to 900 ℃ at a temperature rise rate of 3 ℃/min under an air atmosphere, and the catalyst precursor was calcined for 3 hours₂O₄The porosity is 53 percent, the load of Ni is 10 weight percent, and finally the reduction is carried out in the hydrogen atmosphere at the temperature of 600 ℃, and finally the aluminum-based MOFs derived Ni-based catalyst, namely the catalyst Ni/Al-3, is prepared.

Example 4

An aluminum-based MOFs-derived Ni-based catalyst, referred to as catalyst Ni/Al-4 for short, was prepared in the same manner as in example 1, except that the reduction was carried out in a hydrogen atmosphere at 650 ℃.

Testing of catalyst Performance

Activity and stability testing of the catalyst: 0.2g of the catalyst Ni/Al-1 prepared by the above method was mixed with quartz wool and charged into a fixed bed reaction tube. And introducing mixed gas (H2: CO: Ar is 54:18:28), and testing the activity of the catalyst from the temperature range of 250-800 ℃. After the catalyst activity was determined, a catalyst stability performance test was then performed at 450 ℃.

The results of the performance test are as follows.

X-ray diffraction analysis

As shown in FIG. 1, X-ray diffraction analysis was performed on a sample of Ni/Al-1 catalyst before and after methanation of the synthesis gas. A in fig. 1 is an XRD pattern before activity test; b is the XRD pattern after activity test.

As can be seen from (a) in fig. 1, before the activity test of the catalyst, diffraction peaks of Ni appear at 2 θ ═ 44.5 and 51.9 °, corresponding to (111) and (200) crystal planes of Ni (PDF #04-0850), respectively, and the rest is NiAl₂O₄The diffraction peak of (1). FIG. 1 (b) is an XRD pattern after evaluation of catalyst activity, in which NiAl₂O₄The diffraction peak of (A) is shifted to a low angle to generate Al₂O₃And Ni, which indicates NiAl during the reaction₂O₄Ni in the alloy is reduced, and dynamic phase transition occurs.

2. Temperature programmed reduction analysis

FIG. 2 shows the catalyst precursor NiO/NiAl of the present invention₂O₄H of (A) to (B)₂-a TPR map. As can be seen from FIG. 2, the catalyst has three reduction peaks, wherein the reduction peaks superimposed at low temperature and medium temperature are respectively the reduction of NiO into alpha-type Ni which has weak effect on the carrier⁰And beta type Ni strongly acting with the carrier⁰While the reduction peak at 800 ℃ belongs to NiAl₂O₄Reduction to gamma-type Ni⁰Reduced peak of (2). Because the catalyst has three types of reduction peaks, Ni can be continuously reduced in the using process of the catalyst, a progressive reduction mode is presented, so that the active site of active metal Ni is better utilized, and the catalyst is ensured to keep catalytic activity and stability in a wide temperature window.

3. Transmission electron microscopy analysis

Fig. 3 is a TEM image of the catalyst of the present invention, wherein b in fig. 3 is an enlarged view of a. It can be seen from fig. 3 that the catalyst has a relatively obvious and abundant pore structure, and the active metal is uniformly dispersed.

4. Activity assay

FIG. 4 shows the results of the activity test of the catalyst of the present invention. In FIG. 4, the catalyst is treated at a temperature of 250 to 800 ℃ under 0.1MPa at a space velocity of 15000 ml/g^-1·h^-1CO methanation activity test performed under conditions. As can be seen from the figure, the catalytic activity of the catalyst Ni/Al is increased along with the increase of the temperature within the range of 300-450 ℃. The CO conversion rate of the catalyst reaches 98.5 percent at 400 ℃, and CH₄The selectivity reaches 73 percent.

5. Stability test

FIG. 5 is a stability performance test of the catalyst of the present invention. From FIG. 5 it can be seen that the catalyst reacted for 90h at 450 ℃ with CO conversion and CH₄The selectivity remains substantially unchanged. The catalyst prepared by the invention has better thermal stability.

The experimental results show that:

(1) the catalyst Ni/MOF-Al can generate dynamic phase transformation after high-temperature roasting, and after reduction, the catalyst promotes the active nickel to react with the carrier weakly⁰And strongly acting beta-type Ni⁰And can reduce gamma-type Ni under high-temperature reaction conditions⁰NiAl of spinel structure₂O₄The three forms of the catalyst exist, so that the continuous reduction of the active components at low temperature, medium temperature and high temperature is realized, a progressive reduction mode is presented, the catalyst is effectively ensured to have enough active sites within the reaction temperature range of 200-900 ℃, and the activity of the catalyst is ensured.

(2) The catalyst Ni/MOF-Al of the invention generates dynamic phase transition in the process of CO methanation strong exothermic reaction, and realizes NiAl with spinel structure which is difficult to reduce at medium-high reaction temperature₂O₄The nickel in the catalyst is reduced, and the high thermal stability of the catalyst is ensured.

(3) The catalyst Ni/MOF-Al can reduce active nickel from NiO which is easy to reduce and can also reduce NiAl with a spinel structure which is difficult to reduce in the prior art in the process of methanation of CO₂O₄Active nickel is reduced.

The catalyst Ni/MOF-Al shows better low-temperature activity in a CO methanation activity test, and the catalyst has no activity reduction in a stability test within 90h, which indicates that the catalyst has better high thermal stability, so that the catalyst of the invention keeps better catalytic activity in a wide temperature range.

Claims

1. An aluminum-based MOFs-derived Ni-based catalyst, characterized in that: the precursor of the catalyst is composed of a carrier and a nickel component, wherein the carrier is a MOF-Al-derived micropore with a porosity of 45 to 55% and NiAl ₂ O ₄ with a mesoporous structure, the total content of Ni in the precursor is 5wt% to 20wt%.

2 . The Ni-based catalyst derived from aluminum-based MOFs according to claim 1 , wherein after reducing the precursor in a hydrogen atmosphere at a temperature of 400-650° C., the nickel component is used as an active component. 3 . α-type Ni ⁰ and β-type Ni ⁰ exist.

3 . The Ni-based catalyst derived from aluminum-based MOFs according to claim 2 , wherein in the CO hydrogenation reaction of synthesis gas, the reaction temperature is 700-900° C. in the reaction atmosphere of the NiAl ₂ O ₄ in the reaction atmosphere. 4 . Nickel is reduced to the active component γ-type Ni ⁰ .

4. The aluminum-based MOFs-derived Ni-based catalyst according to claim 2, wherein the content of the α-type Ni ⁰ is 5-10%, and the content of the β-type Ni ⁰ is 25-35%. The total mass of Ni in the catalyst is the benchmark.

5 . The Ni-based catalyst derived from aluminum-based MOFs according to claim 3 , wherein at a reaction temperature of 700-900° C., the content of γ-type Ni ⁰ is 50-60%, based on the total mass of Ni in the catalyst. 6 .

6. A preparation method of an aluminum-based MOFs-derived Ni-based catalyst according to any one of claims 1 to 5, the preparation method comprising the following steps:

Step 1: Preparation of metal organic framework support MOF-Al using soluble aluminum salt, dicarboxylic acid and water;

Step 2: immersing the metal-organic framework carrier MOF-Al in a mixed solution of soluble nickel salt and alcohol, and then calcining to prepare catalyst precursor NiO/NiAl ₂ O ₄ ;

Step 3: reducing the catalyst precursor NiO/NiAl ₂ O ₄ in a hydrogen atmosphere to obtain the aluminum-based MOFs-derived Ni-based catalyst.

7. The preparation method of aluminum-based MOFs-derived Ni-based catalyst according to claim 6 or 7, wherein the molar ratio of the soluble aluminum salt to the dicarboxylic acid is 1:10-10:1, Preferably 3:1 to 1:3; more preferably 2:1.

8 . The method for preparing an aluminum-based MOFs-derived Ni-based catalyst according to claim 6 or 7 , wherein the step (1) has a reaction temperature of 200° C. to 300° C. and a reaction time of 60 to 100 h. 9 .

9. The preparation method of aluminum-based MOFs-derived Ni-based catalyst according to claim 6 or 7, wherein the roasting temperature in the step (2) is 850 ℃～950 ℃, preferably 875 ℃～900 ℃ ℃, the calcination time is 1-4h, preferably 2-3h.

10. A use of the aluminum-based MOFs-derived Ni-based catalyst according to claim 1 in the CO methanation of syngas.