A coupling reaction catalyst, its preparation method and use

Abstract

The present application relates to the technical field of catalyst preparation, and particularly relates to a coupling reaction catalyst, a preparation method and application thereof. The coupling reaction catalyst comprises a carrier, an active agent and an active assistant loaded on the carrier; the carrier is an Al2O3-Fe3O4 self-assembled carrier; the active agent is nickel oxide, and the active assistant comprises A agent, B agent and C agent; the A agent is a transition metal oxide, the B agent is a rare earth metal oxide, and the C agent is an alkali metal oxide; in the catalyst, the rare earth element loading is 2-3 wt.%, the alkali metal element loading is 1-2 wt.%, the transition metal element loading is 2-3 wt.%, and the nickel element loading is 30-35 wt.%. The coupling reaction catalyst has high single-pass conversion rate and selectivity, good catalytic stability, low cost, low risk coefficient, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, in particular to a coupling reaction catalyst and a preparation method and application thereof. BACKGROUND

[0002] 2,2'-dipyridyl is a raw material for synthesizing paraquat, which is a contact desiccant or herbicide with certain systemicity developed by Syngenta in 1958, and the mechanism of action is to destroy plant cells by generating superoxide. The drug has a quick effect and a wide weed spectrum, and is a non-selective contact-type herbicide.

[0003] At present, one method for catalytically synthesizing 2,2'-dipyridyl is to use anhydrous Raney nickel (Raney Ni) as a catalyst and pyridine as a raw material to prepare 2,2'-dipyridyl by one-step coupling. However, this technology has the disadvantages of low single-pass conversion rate, easy oxidation, and easy explosion;

[0004] Another method is to use pyridine as a raw material to generate 2,2'-dipyridyl under the action of a noble metal catalyst such as Rh, Ru / C or Pt / C. This method has the advantages of high atom economy and green environmental protection, but the disadvantages are that a noble metal catalyst is used, the catalyst is expensive, and the single-pass conversion rate of pyridine is low and the catalyst is easy to deactivate. SUMMARY

[0005] (1) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a coupling reaction catalyst and a preparation method and application thereof, which solves the technical problems of low single-pass conversion rate, poor selectivity, poor stability, and high price of the existing catalyst.

[0007] (2) Technical solutions

[0008] In order to achieve the above-mentioned purposes, the main technical solutions adopted by the present application include:

[0009] In a first aspect, the present application provides a coupling reaction catalyst, which is composed of a carrier, and an active agent and an active adjuvant loaded on the carrier;

[0010] The carrier is an Al2O3-Fe3O4 self-assembled carrier;

[0011] The active agent is a nickel oxide, and the active adjuvant includes an A agent, a B agent, and a C agent, the A agent is a transition metal oxide, the B agent is a rare earth metal oxide, and the C agent is an alkali metal oxide;

[0012] The rare earth element loading in the catalyst is 2-3 wt.%, the alkali metal element loading is 1-2 wt.%, the transition metal element loading is 2-3 wt.%, and the nickel element loading is 30-35 wt.%.

[0013] Optionally, the transition metal element is selected from at least one of chromium, copper, zinc, cobalt, zirconium and manganese.

[0014] Optionally, the alkali metal element is selected from at least one of potassium and sodium.

[0015] Optionally, the rare earth metal element is selected from at least one of cerium, praseodymium, neodymium, promethium and lanthanum.

[0016] The modification of the Al2O3-Fe3O4 self-assembled carrier under alkaline conditions overcomes the disadvantage that the acidic carrier is not conducive to the direct coupling reaction of pyridine to form 2,2'-bipyridine. Meanwhile, the appropriate amount of alkaline addition can improve the carbon deposition resistance of the nickel-based catalyst, reduce the sintering and agglomeration of the catalyst during secondary calcination, and is conducive to the uniform distribution of the metal loading, thereby improving the catalytic activity. Under the condition of insufficient alkalinity, the alkaline condition cannot be provided. Under the condition of excessive alkalinity, the catalyst agglomeration is increased, and the catalytic activity is reduced.

[0017] The modification of the Al2O3-Fe3O4 self-assembled carrier by the rare earth metal can make the electronic distribution of the nickel element in the carrier more uniform, thereby increasing the activity and stability of the catalyst.

[0018] In a second aspect, the present application provides a preparation method of a coupling reaction catalyst, which comprises the following steps:

[0019] S1, preparation of an Al2O3-Fe3O4 self-assembled carrier;

[0020] S11, preparation of an aluminum sulfate and urea mixed solution, reaction at 90℃ for 5h; after cooling to room temperature, centrifugal separation with deionized water and anhydrous ethanol twice, and drying at 85℃ in a vacuum drying box for 10h to obtain an aluminum oxide precursor;

[0021] S12, measuring 2 portions of DMF, adding 4 portions of trimesic acid, stirring for 15 minutes, and then adding 20 portions of the aluminum oxide precursor;

[0022] After stirring for 10 minutes, 10 portions of H2O, 5 portions of ferric chloride, 2 portions of ferrous chloride and 2 portions of concentrated ammonia water are added in sequence; and stirring and reaction for 30-60 minutes;

[0023] S13, centrifugal separation of the product of S12 with DMF and anhydrous methanol three times, drying at 500℃ for 3 hours under inert atmosphere protection to obtain an Al2O3-Fe3O4 self-assembled carrier;

[0024] S2, surfactants, and active ingredients are loaded onto a carrier;

[0025] S21. Take 20-30 parts of nickel nitrate, add 20-25 parts of deionized water, 4-6 parts of transition metal soluble salt, 2-4 parts of rare earth metal soluble salt and 0.5-1.5 parts of alkali metal soluble salt, and stir to dissolve;

[0026] S22. Take the solution after dissolving S21, add 7 parts of Al2O3-Fe3O4 self-assembled support to it, evaporate, and after the solution is completely evaporated, place it in an oven at 80℃ to dry overnight to obtain the catalyst precursor.

[0027] S3. Secondary calcination to prepare the final product;

[0028] The above-mentioned catalyst precursor was placed in a muffle furnace and calcined at 800-900℃ under an inert atmosphere to obtain the final catalyst; wherein the rare earth element loading was 2-3 wt.%, the alkali metal element loading was 1-2 wt.%, the transition metal element loading was 2-3 wt.%, and the nickel element loading was 30-35 wt.%.

[0029] When the nickel loading is low, the catalyst activity is not high; when the nickel loading is close to 35%, the pyridine conversion reaches its maximum and tends to stabilize, achieving the best surface monodispersity performance. When the loading exceeds the threshold, as the loading increases, accumulation and agglomeration occur, which is detrimental to the catalytic performance.

[0030] The introduction of transition metals into the catalyst can improve the catalytic activity and selectivity of nickel. However, when the proportion of transition metals is large, the transition metals and nickel metal compete for the channel of the support, and the catalytic performance decreases.

[0031] Optionally, the aluminum sulfate and urea mixed solution prepared in S11, Al 3+ The concentrations of urea and urea were 0.1 mol·L⁻¹. -1 and 0.8 mol·L -1 .

[0032] Optionally, the evaporation conditions are: rotary evaporation speed of 70-80 r / s and temperature of 60-65℃.

[0033] Excessive temperature and rotation speed in rotary evaporation will lead to uneven loading of activators and active additives, reducing the bonding strength with the support, and thus reducing the catalytic activity and stability of the catalyst. Conversely, excessively low temperature or rotation speed in rotary evaporation will not achieve the desired solvent evaporation effect.

[0034] Optionally, the specific surface area of ​​the Al2O3-Fe3O4 self-assembled carrier is 170 m². 2 / g, with a pore size of 30nm.

[0035] The pore size provides a place for the subsequent active agent, active assistant metal element, and increases the adsorption performance; the larger the specific surface area of the carrier, the richer the pore structure, the more active sites suitable for the reaction, and the more conducive to the catalysis.

[0036] Compared with the Al2O3 carrier without Fe3O4 self-assembly, the Al2O3-Fe3O4 self-assembly carrier has more active sites, and the performance of the Al2O3-Fe3O4 self-assembly carrier is significantly improved. Due to the synergistic effect of Fe and Al, the pores of the Al2O3-Fe3O4 self-assembly carrier are larger, the specific surface area of the carrier is expanded, the catalytic stability is higher, the service life of the catalyst is enhanced, and the selectivity of the catalyst is improved. At the same time, the maximum loading capacity of nickel in the Al2O3-Fe3O4 self-assembly carrier can reach 35%, which is higher than the maximum loading capacity of nickel in the Al2O3 carrier without Fe3O4 self-assembly. Under the same preparation conditions, the maximum loading capacity of nickel in the Al2O3 carrier without Fe3O4 self-assembly is 25%.

[0037] Optionally, the calcination temperature in S3 is 800℃, and the calcination time is 10 hours.

[0038] The calcination conditions in S3 break the block structure of the catalyst, reduce the size of the catalyst, provide more active sites, increase the close combination between metals, reduce the side reactions and carbon deposition of the catalyst, prolong the service life of the catalyst, and improve the selectivity of the catalyst.

[0039] In a third aspect, the application provides an application of the coupling reaction catalyst, which is applied to catalyze the preparation of 2,2'-bipyridine through pyridine coupling.

[0040] (III) Beneficial effects

[0041] The application has the beneficial effects that the coupling reaction catalyst is obtained by taking inexpensive alumina as a carrier precursor and taking inexpensive nickel nitrate, a rare earth metal soluble salt, an alkali metal soluble salt, and a transition metal soluble salt as raw materials, and the production cost is effectively controlled.

[0042] The Al2O3-Fe3O4 self-assembly carrier expands the specific surface area of the carrier, and the single-pass conversion rate and the selectivity are improved in the process of preparing 2,2'-bipyridine through pyridine coupling.

[0043] The active agent, the active assistant, and the carrier form an orderly whole, the Al2O3-Fe3O4 self-assembly carrier can provide a regular and sufficient pore environment and more active sites, the regular pore structure helps to avoid the agglomeration of the loaded metal particles, the metal particles are more uniformly dispersed, and the specific surface area of the carrier is increased. The Al2O3-Fe3O4 self-assembly carrier improves the catalyst activity through the interaction with the active agent and the assistant, and improves the catalytic efficiency.

[0044] The transition metal element and the nickel element are embedded into the Al2O3-Fe3O4 self-assembled channel carrier, the solidification strength is enhanced, and the metal dispersion is expanded. The transition metal is doped in the nickel-based catalyst, which can not only improve the dispersion of the nickel element, but also disperse the electron distribution of the nickel atom, effectively protect and stabilize the nickel element particles, avoid the sintering of the nickel particles in the use process, improve the stability of the catalyst, and effectively delay the deactivation of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is the 2,2'-bipyridine nuclear magnetic resonance hydrogen spectrum;

[0046] Figure 2 is the 2,2'-bipyridine nuclear magnetic resonance carbon spectrum. DETAILED DESCRIPTION

[0047] In order to better explain the present application, the following specific embodiments are described in detail. In the following examples, the parts refer to the mass parts if not specifically stated.

[0048] Example 1

[0049] The present embodiment provides a preparation method of a coupling reaction catalyst, and the steps are as follows:

[0050] In the preparation process, the reagents are calculated by weight parts,

[0051] S1, preparation of Al2O3-Fe3O4 self-assembled carrier;

[0052] S11, prepare an aluminum sulfate and urea mixed solution, and react at 90°C for 5h; after cooling to room temperature, centrifugal separation with deionized water and anhydrous ethanol twice, and drying at 85°C in a vacuum drying box for 10h to obtain an aluminum oxide precursor;

[0053] S12, measure 2 parts of DMF, add 4 parts of trimesic acid, stir for 15 minutes, and then add 20 parts of the aluminum oxide precursor;

[0054] After stirring for 10 minutes, 10 parts of H2O and 5 parts of ferric chloride, 2 parts of ferrous chloride and 2 parts of concentrated ammonia are added in sequence; and the reaction is stirred for 30-60 minutes;

[0055] S13, centrifugal separation of the product of S12 with DMF and anhydrous methanol three times, drying at 500°C for 3 hours under inert atmosphere protection to obtain an Al2O3-Fe3O4 self-assembled carrier;

[0056] S2, loading of the active agent and the active co-agent on the carrier;

[0057] S21, take 20 parts of nickel nitrate, add 20 parts of deionized water, 4 parts of transition metal soluble salt, 2 parts of rare earth metal soluble salt and 0.5 parts of alkali metal soluble salt, stir and dissolve;

[0058] Among them, the transition metal soluble salt is selected as zirconium nitrate, the alkali metal soluble salt is selected as potassium nitrate, and the rare earth metal soluble salt is selected as cerium nitrate;

[0059] S22, take the solution after dissolving in S21, add 7 parts of Al2O3-Fe3O4 self-assembly carrier to it, evaporate, and place it in an 80℃ oven to dry overnight after the solution is completely evaporated, to obtain a catalyst precursor;

[0060] S3, secondary calcination to prepare the final product;

[0061] Place the above catalyst precursor in a muffle furnace under the protection of an inert atmosphere, and calcine at 800-900℃ to obtain the final catalyst;

[0062] Among them, the rare earth element loading is 2-3wt.%, the alkali metal element loading is 1-2wt.%, the transition metal element loading is 2-3wt.%, and the nickel element loading is 30-35wt.%.

[0063] Example 2

[0064] The present embodiment provides a preparation method of a coupling reaction catalyst, and the steps are as follows:

[0065] During the preparation process, each reagent is calculated by weight parts,

[0066] S1, Al2O3-Fe3O4 self-assembly carrier preparation;

[0067] S11, prepare an aluminum sulfate and urea mixed solution, and react at 90℃ for 5h; After cooling to room temperature, centrifugal separation with deionized water and anhydrous ethanol twice, and drying at 85℃ in a vacuum drying box for 10h, to obtain an alumina precursor;

[0068] S12, take 2 parts of DMF, add 4 parts of trimesic acid, stir for 15 minutes, and then add 20 parts of alumina precursor;

[0069] After stirring for 10 minutes, add 10 parts of H2O, 5 parts of iron chloride, 2 parts of ferrous chloride and 2 parts of concentrated ammonia water in sequence; Stir and react for 30-60 minutes;

[0070] S13, centrifugal separation of the product of S12 with DMF and anhydrous methanol three times, and dry at 500℃ under the protection of an inert atmosphere for 3 hours, to obtain an Al2O3-Fe3O4 self-assembly carrier;

[0071] S2, active agent and active assistant are loaded on the carrier;

[0072] S21, take 30 parts of nickel nitrate, add 20 parts of deionized water, 6 parts of transition metal soluble salt, 4 parts of rare earth metal soluble salt and 1.5 parts of alkali metal soluble salt, stir and dissolve;

[0073] Among them, the transition metal soluble salt is selected as zirconium nitrate, the alkali metal soluble salt is selected as potassium nitrate, and the rare earth metal soluble salt is selected as cerium nitrate;

[0074] S22, take the solution after dissolving in S21, add 7 parts of Al2O3-Fe3O4 self-assembled carrier to it, evaporate, and place it in an oven at 80°C overnight after the solution is completely evaporated, to obtain a catalyst precursor;

[0075] S3, secondary calcination to prepare the final product;

[0076] Place the above catalyst precursor in a muffle furnace under the protection of inert atmosphere, and calcine at 800-900°C to obtain the final catalyst;

[0077] Among them, the loading of rare earth elements is 2-3wt.%, the loading of alkali metal elements is 1-2wt.%, the loading of transition metal elements is 2-3wt.%, and the loading of nickel elements is 30-35wt.%.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 2 is that the alumina precursor prepared in S11 is not subjected to the S12 operation, but is directly placed in a drying box and dried at 500°C for 3 hours to obtain an Al2O3 carrier that has not been reacted with trimesic acid and DMF. The specific surface area of the carrier is 250 m 2 / g, and the pore size is concentrated at 20 nm. The rest of the conditions remain the same as in Example 2.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 2 is that no iron chloride, ferrous chloride, and concentrated ammonia are added in S12, and the same amount of alumina precursor is used instead of iron chloride, ferrous chloride, and concentrated ammonia to obtain an Al2O3 carrier that is not assembled with Fe3O4. The rest of the conditions remain the same as in Example 2.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 2 is that no equal amount of transition metal soluble salt is added in S21. The rest of the conditions remain the same as in Example 2.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 2 is that no equal amount of rare earth metal soluble salt is added in S21. The rest of the conditions remain the same as in Example 2.

[0086] Comparative Example 5

[0087] The difference between this comparative example and Example 2 is that no equivalent amount of alkali metal soluble salt is added in S21, and the rest of the conditions remain the same as Example 2.

[0088] Comparative Example 6

[0089] The difference between this comparative example and Example 2 is that the rotary evaporation conditions are set to a rotation speed of 90 r / s and a temperature of 70°C, and the rest of the conditions remain the same as Example 2.

[0090] Comparative Example 7

[0091] The difference between this comparative example and Example 2 is that no secondary calcination is performed, and the rest of the conditions remain the same as Example 2.

[0092] 4 g of the catalyst prepared in Examples 1-2 and Comparative Examples 1-7 is weighed, and then the catalyst bed in the reaction tube of the fixed bed reactor is activated at a temperature of 380°C and a hydrogen flow rate of 100 mL / min for 3 h, and then heated to 450°C. The raw material liquid is continuously injected into the fixed bed reactor at a rate of 1 ml / min using a metering pump, and nitrogen is used as the dilution gas at a flow rate of 30 ml / min, and the reaction temperature is maintained at 220-230°C, and the pressure is 1.5 MPa. Pyridine is coupled to prepare 2,2'-bipyridine under the above conditions.

[0093] Table 1. Catalyst performance test of Examples 1-2 and Comparative Examples 1-7

[0094]

[0095] From the data in Table 1, it can be seen that the catalyst prepared in Comparative Example 7 without secondary calcination has reduced selectivity, and the single-pass conversion rate is reduced after 32 h, and the stability is poor. In Comparative Example 6, the rotary evaporation temperature is too high and the rotation speed is too fast, resulting in a significant decrease in catalyst activity. In Comparative Example 5, no alkali metal element is added, resulting in insufficient catalyst activity and low single-pass conversion rate. In Comparative Example 4, no rare earth metal element is added, resulting in reduced catalyst activity, reduced single-pass conversion rate after 32 h, and poor stability. In Comparative Example 3, no transition metal element is added, resulting in reduced activity and selectivity of the prepared catalyst.

[0096] In Comparative Example 2, the initial conversion rate is not significantly reduced, but the selectivity of 2,2'-bipyridine is significantly reduced. At the same time, the 24 h single-pass conversion rate in Comparative Example 2 is 2.3%, while the 24 h single-pass conversion rate in Example 2 is 4.2%, which shows that the Al2O3-Fe3O4 self-loading carrier significantly increases the service life and selectivity of the catalyst.

[0097] The initial conversion rate in the comparative example 1 has obvious change compared with the example 2, and the single pass conversion rate is reduced more seriously after 32 hours, the single pass conversion rate data is 1.0% after 12 hours, the conversion rate is basically the same as 32 hours, and the catalyst is basically deactivated. The single pass conversion rate data of the example 2 is 9.2% after 12 hours, which shows that the magnetic iron self-assembled composite material loaded by alumina, i.e. Al2O3-Fe3O4 self-assembled carrier, significantly increases the service life of the catalyst.

[0098] The product prepared in the example 2 is confirmed as 2,2'-dipyridyl by nuclear magnetic resonance hydrogen spectrum and nuclear magnetic resonance carbon spectrum, Figure 1 is 2,2'-dipyridyl nuclear magnetic resonance hydrogen spectrum, Figure 2 is 2,2'-dipyridyl nuclear magnetic resonance carbon spectrum.

[0099] The coupling reaction catalyst provided by the application has high single pass conversion rate and selectivity, good catalytic stability, low cost, low risk coefficient, and is suitable for industrial production.

[0100] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and 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 application.

Claims

1. A method for producing a catalyst for a coupling reaction, characterized by, The catalyst is composed of a carrier, and an active agent and an active assistant supported on the carrier; The carrier is an Al2O3-Fe3O4 self-assembled carrier; The active agent is nickel oxide, and the active assistant includes A agent, B agent and C agent, the A agent is a transition metal oxide, the B agent is a rare earth metal oxide, and the C agent is an alkali metal oxide; In the catalyst, the loading of the rare earth element is 2-3 wt.%, the loading of the alkali metal element is 1-2 wt.%, the loading of the transition metal element is 2-3 wt.%, and the loading of the nickel element is 30-35 wt.%; The transition metal element is selected from at least one of chromium, copper, zinc, cobalt, zirconium and manganese; The alkali metal element is selected from at least one of potassium and sodium; The rare earth metal element is selected from at least one of cerium, praseodymium, neodymium, promethium and lanthanum; The preparation method includes the following steps: S1, preparation of an Al2O3-Fe3O4 self-assembled carrier; S11, preparation of an aluminum sulfate and urea mixed solution, reaction at 90°C for 5 hours; after cooling to room temperature, centrifugal separation with deionized water and anhydrous ethanol twice, and drying at 85°C in a vacuum drying box for 10 hours to obtain an aluminum oxide precursor; S12, measuring 2 parts of N,N-dimethylformamide DMF, adding 4 parts of trimesic acid, stirring for 15 minutes, and then adding 20 parts of the aluminum oxide precursor; After stirring for 10 minutes, 10 parts of H2O, 5 parts of iron chloride, 2 parts of ferrous chloride and 2 parts of concentrated ammonia water are sequentially added; stirring and reaction for 30-60 minutes; S13, centrifugal separation of the product of S12 with N,N-dimethylformamide DMF and anhydrous methanol three times, drying at 500°C for 3 hours under inert atmosphere protection to obtain an Al2O3-Fe3O4 self-assembled carrier; S2, loading of the active agent and the active assistant on the carrier; S21, taking 20-30 parts of nickel nitrate, adding 20-25 parts of deionized water, 4-6 parts of a soluble salt of a transition metal, 2-4 parts of a soluble salt of a rare earth metal and 0.5-1.5 parts of a soluble salt of an alkali metal, and stirring and dissolving; S22, taking the solution after dissolving in S21, adding 7 parts of the Al2O3-Fe3O4 self-assembled carrier to the solution, evaporating, and placing in a drying oven at 80°C overnight after the solution is completely evaporated to dryness to obtain a catalyst precursor; the evaporation condition is: rotary evaporation speed 70-80 r / s, and temperature 60-65°C; S3, preparation of a final product by secondary calcination; Placing the above catalyst precursor in a muffle furnace and calcining at 800-900°C under inert atmosphere protection to obtain a final catalyst.

2. The method for preparing a coupling reaction catalyst according to claim 1, characterized by, The S11 aluminum sulfate and urea mixed solution, Al 3+ and the concentration of urea is 0.1 mol·L -1 -1 -1 and 0.8 mol·L -1 -1 .

3. The method for preparing a coupling reaction catalyst according to claim 1, characterized in that, The specific surface area of the Al2O3-Fe3O4 self-assembled support is 170 m 2 / g, with a pore size of 30 nm.

4. The method for preparing a coupling reaction catalyst according to claim 1, characterized in that, The calcination temperature in S3 is 800°C, and the calcination time is 10 hours.

5. The use of the coupling reaction catalyst prepared according to the preparation method of the coupling reaction catalyst according to claim 1, characterized in that, Catalytic pyridine coupling to prepare 2,2'-bipyridine.

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