A nickel-based catalyst taking a ni:edta complex as a nickel source, and a preparation method and application thereof

Abstract

The application discloses a nickel-based catalyst taking a Ni:EDTA complex as a nickel source and a preparation method and application thereof, the nickel source of the nickel-based catalyst is the Ni:EDTA complex, the nickel-based catalyst comprises a carrier and an active component, the active component is a nickel species, the carrier is Al-MCM-41, and the nickel species accounts for 5-25 wt.% of the total mass of the nickel-based catalyst. The nickel-based catalyst prepared by taking the Ni:EDTA complex as the nickel source has a particle size of 4.79-10.19 nm, and the nickel-based catalyst has high catalytic activity and high selectivity of decalin in a catalytic hydrogenation saturation reaction of naphthalene.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and relates to a catalyst for hydrogenation saturation of naphthalene, in particular to a nickel-based catalyst taking a Ni:EDTA complex as a nickel source and a preparation method and application thereof. BACKGROUND

[0002] At present, the global fuel industry is facing many environmental challenges and must meet the requirements and regulations of limiting greenhouse gas emissions. Fossil energy contains a large amount of polycyclic aromatic hydrocarbons, which not only reduces the quality of fuel oil, but also causes environmental pollution due to incomplete combustion. There is an urgent need for efficient deep hydrogenation saturation technology to convert polycyclic aromatic hydrocarbons into naphthenes to improve the quality of oil products, prevent environmental pollution, and at the same time produce high-value-added products. However, there is a stable pi bond structure in polycyclic aromatic hydrocarbons, which is difficult to break, especially for the deep hydrogenation saturation of the last ring, which is very challenging. It is crucial to develop a deep hydrogenation saturation catalyst with high activity and stability. Since naphthalene accounts for a large proportion in the diesel boiling point range products of oil refining and petrochemical plants, it is often used as a detection molecule and is a typical polycyclic aromatic hydrocarbon (PAHs). Catalytic hydrogenation of naphthalene can obtain many high-value-added products: tetrahydronaphthalene, cis- and trans-decahydronaphthalene, which can be used as solvents, nylon production raw materials and jet fuel stabilizers, respectively. It is of great significance to develop an efficient naphthalene deep hydrogenation saturation catalyst.

[0003] At present, there are mainly two types of catalysts for catalytic hydrogenation of polycyclic aromatic hydrocarbons: noble metal catalysts and non-noble metal catalysts. Noble metal catalysts still have good catalytic performance at low temperatures. However, noble metals are expensive and scarce in resources, making it difficult to achieve industrial production. Non-noble metal catalysts (Ni, Mo, Co, etc.) are inexpensive and have good sulfur and nitrogen resistance, but non-noble metal catalysts generally have low hydrogenation degree of naphthalene, poor activity and stability, and harsh reaction conditions requiring high temperature and high pressure. Among them, supported nickel-based catalysts are widely studied and applied in many important industrial catalytic processes as substitutes for noble metal catalysts due to their attractive cost efficiency ratio and ability to activate hydrogen under mild conditions.

[0004] Patent CN109759068A invented a method for preparing a nickel-based catalyst by ultrasonic-assisted wet impregnation, dissolving nickel nitrate in deionized water to obtain an impregnation solution, adding a carrier to the impregnation solution, shaking for 5-30 min, then placing it in an ultrasonic dispersing instrument for ultrasonic dispersion at a power of 50-150 W, then standing for 24-48 hours, and then drying, calcining and reducing to obtain a nickel-based catalyst. Compared with the traditional impregnation method, the catalyst obtained by using ultrasonic assistance can significantly improve the dispersion of Ni and reduce its grain size, but the additional ultrasonic assistance method increases the complexity of catalyst preparation and increases the cost of catalyst preparation, which is difficult to be applied in industrialization.

[0005] Patent CN106694022A invented a kind of nickel-based catalyst for preparing β-phenethyl alcohol and other preparation methods, the nickel-based catalyst includes active component, auxiliary agent, pore-forming agent, modifier, carrier;Using 3~15wt based on the weight of nickel-based catalyst, preferably 5~10% of wood ash as modifier.The catalyst is used in continuous β-phenethyl alcohol preparation process is conducive to further improve the selectivity of β-phenethyl alcohol, improve yield, improve production efficiency.But the catalyst preparation raw material is complex, not only contains alkaline auxiliary agent, including wood ash modifier and pore-forming agent.

[0006] Specifically, for the nickel-based catalyst used in the catalytic hydrogenation saturation reaction of naphthalene, there are still the following problems, the catalytic activity needs to be further improved, and it is difficult to deeply hydrogenate when used in the catalytic hydrogenation saturation reaction of naphthalene, the selectivity of tetrahydro naphthalene in the product is high, and the selectivity of decahydro naphthalene is low.

[0007] Therefore, it is desirable to prepare a nickel-based catalyst with high catalytic activity by a simple preparation method, which can deeply hydrogenate when used in the catalytic hydrogenation saturation reaction of naphthalene, and has high selectivity of decahydro naphthalene. The present application aims to solve the above problems. SUMMARY

[0008] The present application aims to overcome the shortcomings of the prior art, and to solve the problems of low catalytic activity and low selectivity of decahydro naphthalene in the nickel-based catalyst used in the catalytic hydrogenation saturation reaction of naphthalene. The nickel-based catalyst of the present application uses Ni: EDTA complex as the nickel source, and the particle size of the nickel species is 4.79 nm. The nickel-based catalyst has high catalytic activity and high selectivity of decahydro naphthalene when used in the catalytic hydrogenation saturation reaction of naphthalene. In terms of preparation method, the present application first prepares Ni: EDTA complex, and then adjusts its pH value to 9 by ammonia water, and then uses it as the nickel source for stirring and impregnation with the carrier. The present application uses Al-MCM-41 as the carrier, and Ni: EDTA complex as the Ni source to prepare Ni(ED) / Al-MCM-41 catalyst with Ni loading of 15wt%. After reaction for 2h under the reaction conditions of 300℃ and 6MPa, the conversion rate of naphthalene reaches 97.56%, and the selectivity of decahydro naphthalene is 6.88%.

[0009] The point technical solution adopted by the present application is:

[0010] The first aspect of the present application provides a nickel-based catalyst using Ni: EDTA complex as the nickel source. The nickel source of the nickel-based catalyst is Ni: EDTA complex. The nickel-based catalyst includes a carrier and an active component. The active component is a nickel species. The carrier is Al-MCM-41. The nickel species accounts for 5~25wt of the total mass of the nickel-based catalyst.

[0011] Preferably, the particle size of the nickel species is 4.79nm.

[0012] The second aspect of the present application provides a preparation method of the nickel-based catalyst according to the first aspect of the present application, characterized in that the method comprises the following steps:

[0013] (1) a nickel salt and ethylenediaminetetraacetic acid (EDTA) as a chelating agent are weighed and dissolved in deionized water, the solution is stirred and the pH value is adjusted to 9 to obtain a first solution;

[0014] (2) the support and the first solution obtained in step (1) are added to a container and stirred, after the end, the obtained suspension is filtered and washed, then the obtained filter cake is dried, ground, to obtain a catalyst precursor;

[0015] (3) the catalyst precursor obtained in step (2) is calcined and reduced to obtain a nickel-based catalyst with Ni: EDTA complex as a nickel source.

[0016] Preferably, in step (1), the nickel salt is selected from nickel nitrate.

[0017] Preferably, in step (1), the molar ratio of Ni to EDTA in the first solution is 1:1, and the pH value of the solution is adjusted by ammonia water.

[0018] Preferably, in step (2), the support is selected from Al-MCM-41.

[0019] Preferably, in step (2), the stirring temperature is room temperature, the stirring time is 6-24h, the drying temperature is 60-120℃, and the drying time is 6-12h.

[0020] Preferably, in step (3), the calcination treatment conditions are: the calcination temperature is 400-600℃, the calcination time is 2-6h, and the heating rate during the calcination process is 1.5-3℃ / min; the reduction treatment conditions are: the reduction atmosphere is hydrogen, the hydrogen flow rate is 60-100mL / min; the reduction temperature is 200-600℃, the reduction time is 2-4h, and the heating rate during the reduction process is 1.5-3℃ / min.

[0021] The third aspect of the present application provides an application of the nickel-based catalyst according to the first aspect of the present application, characterized in that the nickel-based catalyst is used for the hydrogenation saturation reaction of naphthalene to improve the selectivity of decalin.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. The present application uses Ni: EDTA complex as a nickel source to prepare a nickel-based catalyst with a nickel species particle size of 4.79-10.19nm, wherein the nickel species accounts for 5-25wt.% of the total mass of the nickel-based catalyst.

[0024] 10. The nickel-based catalyst prepared by the method has a high selectivity for decalin.

[0025] 2、The present application is not expected that only with Ni: EDTA complex as Ni source, the particle size of nickel species of nickel-based catalyst and the efficiency of naphthalene deep hydrogenation saturation can be regulated. The Ni(ED) / Al-MCM-41 catalyst prepared by the present application with Al-MCM-41 as carrier and Ni: EDTA complex as Ni source and the loading amount of Ni is 15wt%, after 2h reaction under the reaction condition of 300℃ and 6MPa, the conversion rate of naphthalene reaches 97.56%, and the selectivity of decalin is 6.88%. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 TEM images of catalysts prepared by different Ni sources, wherein (a) (b) are Example 6, (c) (d) are Example 1, (e) (f) are Example 7;

[0027] Figure 2 XPS characterization of catalysts prepared by different Ni sources. DETAILED DESCRIPTION

[0028] The present application is further illustrated by the following examples, which are not intended to limit the present application. The experimental methods in the examples without specific conditions are usually carried out according to the conventional conditions and the conditions described in the manual, or the general equipment, materials, reagents, etc. used according to the conditions suggested by the manufacturers, and if no special instructions are given, they can be obtained from commercial channels.

[0029] The specific steps of the method described in the present application are as follows:

[0030] The synthesis of nickel-based catalyst prepared by Ni: EDTA complex as Ni source is taken as an example.

[0031] (1) Synthesis of catalyst precursor. 500mg of carrier is weighed into a round-bottom flask, and nickel nitrate is used as precursor and ethylenediaminetetraacetic acid (EDTA) is used as chelating agent. The complex is prepared in 10mL of water medium with the molar ratio of Ni to EDTA being 1:1. The final pH value of the above solution is adjusted to 9 with ammonia water, and it is added to the round-bottom flask and stirred with the carrier at room temperature for 12h. The suspension is then filtered and washed, and the obtained filter cake is placed in a blast oven and dried at 120℃ for 12h.

[0032] (2) Calcination and reduction. The ground and dried sample was placed in a muffle furnace at 500 °C for 4 h with a heating rate of 2.5 °C / min. The calcined sample was then ground and placed in a H2atmosphere furnace at 200 °C for 4 h with a heating rate of 2.5 °C / min and a H2flow of 100 mL / min to obtain the Ni-based catalyst with different supports using Ni:EDTA complex as the Ni source, labeled as Ni(ED) / different supports. The theoretical loading of Ni was 15 wt%.

[0033] In particular:

[0034] Example 1: Preparation of Ni-based catalyst with Al-MCM-41 as support (nickel nitrate as Ni source)

[0035] The excess impregnation method was used to prepare the Ni-based catalyst with different supports using nickel nitrate as the Ni source. The specific steps are as follows. First, 500 mg of Al-MCM-41 support was weighed into a 50 mL round-bottom flask. Then, a certain amount of nickel nitrate (371.5 mg) was weighed into 10 mL of deionized water and ultrasonically dissolved, and then added to the round-bottom flask. The support was stirred and impregnated at room temperature for 12 h. After stirring, the suspension was suction filtered and washed three times with deionized water. The obtained solid product was placed in a blast drying oven at 120 °C for 12 h. Then, the dried sample was ground and placed in a muffle furnace at 500 °C for 4 h under an air atmosphere with a heating rate of 2.5 °C / min. The calcined sample was then ground and placed in a H2atmosphere furnace at 400 °C for 4 h with a heating rate of 2.5 °C / min and a H2flow of 100 mL / min to obtain the Ni-based catalyst with Al-MCM-41 as the support, labeled as Ni(NN) / Al-MCM-41. The theoretical loading of metal Ni was 15 wt%. The TEM image is shown in FIGS. 1(a) and 1(b), and the average particle size of the nickel particles was 8.50 ± 0.43 nm. Figure 1 (c)(d) shows that the average particle size of the nickel particles was 8.50 ± 0.43 nm.

[0036] Example 2: Preparation of Ni-based catalyst with SBA-15 as support (nickel nitrate as Ni source)

[0037] The specific implementation conditions were similar to those of Example 1, but the support was changed to SBA-15, and the other preparation steps were consistent, i.e., Ni(NN) / SBA-15 was obtained.

[0038] Example 3: Preparation of Ni-based catalyst with ZSM-5 as support (nickel nitrate as Ni source)

[0039] The specific implementation conditions were similar to those of Example 1, but the support was changed to ZSM-5, and the other preparation steps were consistent, i.e., Ni(NN) / ZSM-5 was obtained.

[0040] Example 4: Preparation of nickel-based catalyst with Al2O3 as support (nickel nitrate as Ni source)

[0041] The specific implementation conditions are similar to those of Example 1, but the support is changed to Al2O3, and the other preparation steps are the same, i.e., Ni(NN) / Al2O3 is obtained.

[0042] Example 5: Preparation of nickel-based catalyst with Hβ as support (nickel nitrate as Ni source)

[0043] The specific implementation conditions are similar to those of Example 1, but the support is changed to Hβ, and the other preparation steps are the same, i.e., Ni(NN) / Hβ is obtained.

[0044] Example 6: Preparation of nickel-based catalyst with nickel acetate as Ni source

[0045] 500 mg of Al-MCM-41 was weighed into a round-bottom flask, and a certain amount of nickel acetate was ultrasonically dissolved in 10 mL of deionized water as a precursor solution. The Ni precursor solution was added to the round-bottom flask containing the support, and impregnation and stirring were performed at room temperature for 12 h. After the impregnation was completed, the suspension was suction-filtered and washed with deionized water three times, and the obtained solid product was dried at 120°C for 12 h. Then the dried sample was ground and placed in a muffle furnace for calcination at 500°C for 4 h, with a heating rate of 2.5°C / min. The calcined sample was ground and placed in a hydrogen atmosphere furnace, and reduced at 400°C for 4 h at a heating rate of 2.5°C / min, with a hydrogen flow of 100 mL / min. The catalyst prepared with nickel acetate as the Ni source was marked as Ni(AC) / Al-MCM-41. The theoretical loading of metal Ni was 15 wt%. Figure 1 The TEM images are shown in (a) and (b), and the nickel particles are not very uniformly dispersed on the support, with an average particle size of 10.19±0.52 nm.

[0046] Example 7: Preparation of nickel-based catalyst with Ni:EDTA complex as Ni source

[0047] The specific implementation conditions are similar to those of Example 6, but the Ni source is changed to a Ni:EDTA complex. Specifically, a complex was prepared in 10 mL of water medium with a molar ratio of Ni to EDTA of 1:1, using nickel nitrate as the precursor and ethylenediaminetetraacetic acid (EDTA) as the chelating agent. The final pH value of the above solution was adjusted to 9 with ammonia water, and the other preparation steps were unchanged, i.e., Ni(ED) / Al-MCM-41 was obtained. Figure 1 The TEM images are shown in (e) and (f), and the nickel particles are highly dispersed, with an average particle size of 4.79±0.53 nm.

[0048] Example 8: Nickel-based catalyst with a loading of 10 wt% (with Ni:EDTA complex as Ni source)

[0049] Example 6: Preparation of 10-Ni(ED) / Al-MCM-41 catalyst

[0050] Example 9: Nickel-based catalyst with 20 wt% loading (using Ni:EDTA complex as Ni source)

[0051] The preparation conditions are similar to those of Example 6, but the loading of Ni is 20%, and 495.5 mg of nickel nitrate and 497.9 mg of ethylenediaminetetraacetic acid (EDTA) are prepared in a 10 mL aqueous medium in a molar ratio of 1:1, and the solution pH is adjusted to 9 with ammonia water, and the other preparation steps are the same, to obtain a 20-Ni(ED) / Al-MCM-41 catalyst.

[0052] Example 10: Naphthalene hydrogenation saturation reaction using nickel-based catalysts prepared using different supports

[0053] The catalysts obtained in Examples 1, 2, 3, 4, 5 above are applied to the catalytic hydrogenation saturation reaction of naphthalene. The catalytic activity of the nickel-based catalysts prepared using different supports in the hydrogenation saturation of naphthalene is tested in a steel autoclave with a capacity of 100 ml. The reaction solvent is n-tridecane (30 mL), and the internal standard is n-hexadecane (100 μL). Naphthalene (50 mg) and the catalyst (50 mg) are added to the autoclave. The reaction mixture is stirred at a speed of 600 rpm, and after the autoclave is heated to a reaction temperature of 300°C, hydrogen is introduced to a reaction pressure of 6 MPa. After 2 h of reaction, the autoclave is cooled to room temperature, the pressure is reduced to atmospheric pressure, and the sample is taken.

[0054] The detailed reaction results of naphthalene hydrogenation over the nickel-based catalysts prepared with different supports are shown in Table 1. As can be seen from the table, the conversion of naphthalene over all the catalysts is not high, and does not exceed 50%, and the main product is tetrahydronaphthalene, and the selectivity to decahydronaphthalene is very low. Relatively speaking, the performance of the catalysts with Al-MCM-41 and SBA-15 as the supports is better, and the conversion of naphthalene over them is more than 40%, and the conversion of naphthalene over the catalysts with ZSM-5, Al2O3 and Hβ as the supports is very low, and the conversion of naphthalene is not more than 40%. Among them, the catalytic performance of Ni(NN) / Al-MCM-41 is the best, and the conversion of naphthalene is 47.54%, which may be due to the mesoporous structure of the Al-MCM-41 support, which makes the reactants and products easy to mass transfer and diffuse.

[0055] Example 11: Naphthalene hydrogenation saturation reaction over catalysts prepared with different Ni sources

[0056] The specific implementation conditions are similar to those of Example 10, but the catalysts used for the reaction are those of Examples 1, 6 and 7. The product analysis results of the naphthalene hydrogenation reaction over the catalysts are shown in Table 2. Different Ni precursors have a great influence on the performance of the nickel-based catalysts. As can be seen, the catalyst prepared with nickel acetate as the Ni source has a poor effect on naphthalene hydrogenation, and the conversion of naphthalene is only 35.56%; the conversion of naphthalene over the catalyst prepared with nickel nitrate as the Ni source is 47.54%, and the catalyst prepared with the Ni:EDTA complex as the Ni source has the best performance, and the conversion of naphthalene is 97.56%, which is obviously improved compared with the former two. This may be due to the fact that the catalyst prepared with the Ni:EDTA complex as the Ni source has smaller metal Ni particle size and higher metal dispersion, which produces more metal active sites, thereby further improving the catalytic activity. This is also unexpected by the present application, and only by using the Ni:EDTA complex as the Ni source can a nickel-based catalyst with small metal Ni particle size and high metal dispersion be obtained. The TEM images of the catalysts prepared with different Ni sources are shown in Figure 1 As can be seen from the images, the Ni particles on the Ni(AC) / Al-MCM-41 catalyst are relatively large, and the size is 10.19 nm, while the particle size of the Ni species loaded on the Ni(NN) / Al-MCM-41 catalyst is 8.50 nm. In comparison, the average size of the Ni particles on the Ni(ED) / Al-MCM-41 catalyst is only 4.79 nm, and the Ni metal particles are highly dispersed on the support. The smaller the active metal particle size, the higher the dispersion, the more active sites exposed, and the better the catalytic activity. In addition, the metal on the catalyst prepared with the Ni:EDTA complex as the Ni source interacts strongly with the support, which makes the Ni species form an electron-deficient state, which helps to enhance the adsorption of H2, thereby promoting the naphthalene hydrogenation reaction. The XPS characterization of the catalysts prepared with different Ni sources is shown in Figure 2The diffraction peaks at 857.5 eV and 875.1 eV are attributed to the metal Ni species, and the diffraction peaks at 859.1 eV and 877.9 eV are attributed to the Ni 2+ As can be seen from the figure, compared with the catalysts prepared with nickel acetate and nickel nitrate as the Ni source, the binding energy of the metal Ni species on the catalyst prepared with the Ni: EDTA complex as the Ni source obviously moves to a higher position, which indicates that there is a strong interaction between the metal Ni species and the carrier, which makes the supported Ni species highly dispersed on the carrier. At the same time, the Ni species undergoes electron transfer, which makes the Ni form an electron-deficient state, which is helpful to promote the adsorption of H2, thereby further improving the efficiency of the hydrogenation saturation of naphthalene.

[0057] Example 13: Naphthalene hydrogenation saturation reaction over nickel-based catalysts with different Ni loadings

[0058] The specific implementation conditions are similar to those of Example 10, but the catalysts used for the reaction are those of Examples 7, 8, and 9. The product analysis results of the naphthalene hydrogenation reaction over each catalyst are shown in Table 3. When the loading of Ni is 10 wt%, the conversion rate of naphthalene is very low, only 37.05%, which is due to the low loading of the active component, which results in a weak ability of the catalyst to adsorb hydrogen, so that the degree of naphthalene hydrogenation reaction is low. When the loading of Ni is increased to 15 wt%, the catalyst has excellent hydrogenation performance, the conversion rate of naphthalene is 97.56%, and the selectivity to decalin is 7.05%, which is significantly higher than the selectivity of other catalysts to decalin. This is due to the increase in the active component, which increases the ability of the catalyst to adsorb hydrogen, which is helpful for the hydrogenation saturation reaction of naphthalene. Further increasing the loading of Ni to 20 wt% does not significantly change the catalytic activity, and the conversion rate of naphthalene is 96.57%. In summary, only the loading of an appropriate amount of Ni can maximize the catalytic activity.

[0059] Table 1 Reaction data of naphthalene hydrogenation over nickel-based catalysts with different supports

[0060]

[0061] Table 2 Reaction data of naphthalene hydrogenation over catalysts with different Ni sources

[0062]

[0063] Table 3 Reaction data of naphthalene hydrogenation over catalysts with different Ni loadings

[0064]

[0065] The above has made the exemplary description to the present application, should indicate that, in not departing from the core of the present application, any simple change, modification or other field technicians can not spend the equivalent replacement of creative labor falls into the protection scope of the present application.

Claims

1. An application of a nickel-based catalyst, characterized in that, The nickel-based catalyst was used in the semi-hydrogenation reaction of naphthalene to improve the selectivity and yield of tetrahydronaphthalene to over 90%. The nickel source of the nickel-based catalyst is a Ni:EDTA complex. The nickel-based catalyst includes a support and an active component. The active component is a nickel species, and the support is Al-MCM-41. The nickel species accounts for 15-20 wt.% of the total mass of the nickel-based catalyst. The particle size of the nickel species is 4.79 nm; The preparation method of the nickel-based catalyst includes the following steps: (1) Weigh out nickel salt and ethylenediaminetetraacetic acid as chelating agents, dissolve them in deionized water, stir and adjust the pH of the solution to 9 to obtain the first solution; (2) Add the carrier and the first solution obtained in step (1) into a container and stir. After the stirring is completed, the resulting suspension is filtered and washed. Then the filter cake is dried and ground to obtain the catalyst precursor. (3) The catalyst precursor obtained in step (2) is calcined and reduced to obtain a nickel-based catalyst with Ni:EDTA complex as nickel source; In step (1), the nickel salt is selected from nickel nitrate; In step (1), the molar ratio of Ni to EDTA in the first solution is 1:1, and the pH value of the solution is adjusted with ammonia. In step (2), the carrier is selected from Al-MCM-41; In step (2), the stirring temperature is room temperature, the stirring time is 24 hours, the drying temperature is 120°C, and the drying time is 12 hours. In step (3), the calcination conditions are: calcination temperature of 500℃, calcination time of 4h, and heating rate of 2.5℃ / min during the calcination process. In step (3), the reduction conditions are as follows: the reduction atmosphere is hydrogen, the hydrogen flow rate is 100 mL / min, the reduction temperature is 400℃, the reduction time is 4 h, and the heating rate during the reduction process is 2.5℃ / min.

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