Preparation method of supported Ni-based alloy catalyst
By loading tungsten and nickel compounds onto an alumina support to form a Ni-W alloy catalyst, the problem of poor selectivity of Ni-based catalysts was solved by utilizing the SMSI effect, achieving efficient and stable butadiene hydrogenation and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-11-18
- Publication Date
- 2026-05-19
AI Technical Summary
Existing Ni-based catalysts exhibit poor selectivity in the selective hydrogenation of butadiene, and are prone to over-hydrogenation to butane, limiting their industrial application. Furthermore, existing catalyst preparation methods are complex or costly, making it difficult to meet industrial demands.
Tungsten and nickel compounds were loaded onto an alumina support using an impregnation method, and then subjected to air calcination and hydrogen reduction to form a Ni-W alloy catalyst. The strong metal-support interaction (SMSI) between tungsten oxide and nickel was used to form a core-shell structure, which improved the selectivity and stability of the catalyst.
The catalyst's selectivity and stability were improved, production costs were reduced, efficient hydrogenation conversion of butadiene and high butene yield were achieved, and the catalyst's service life was extended.
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Figure CN122057529A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a supported Ni-based alloy catalyst. Background Technology
[0002] Catalytic cracking refining and steam cracking to produce ethylene are important sources of C4 fractions. C4 fractions typically contain trace amounts of butadiene (1000-2000 ppm), which must be removed to below 50 ppm before downstream reaction processes (such as butene-involved alkylation and polymerization). Otherwise, even trace amounts of butadiene can form oligomers and polymers, poisoning the catalyst and reducing product quality. For example, in the alkylation reaction of isobutane and butene in C4 fractions to produce gasoline, trace amounts of butadiene in the alkylation feedstock not only react with acids to form corresponding esters, increasing acid consumption, but also polymerize under acidic catalysts to form polymers or viscous heavy oils, raising the dry point and lowering the octane number of the alkylate, directly affecting the yield and quality of the alkylate. To address these issues, industrial processes typically pretreat the C4 feedstock before it enters the reaction unit. Selective hydrotreating is a relatively economical and efficient method for removing butadiene. Selective butadiene removal via C4 fraction hydrogenation is typically carried out in a catalyst-packed fixed-bed reactor, requiring hydrogen as a reducing atmosphere. The key to selective butadiene hydrogenation lies in controlling the partial hydrogenation of reactants to either 1-butene or 2-butene, while simultaneously preventing the hydrogenation of the butene fraction in the C4 fraction to butane, or inducing oligomerization reactions that lead to carbon deposition and rapid deactivation on the catalyst surface. In short, side reactions can result in substandard C4 fraction product quality or reduced butene yield.
[0003] Since the 1950s, researchers have been dedicated to finding highly efficient catalysts for the selective hydrogenation of 1,3-butadiene. Initially, metal sulfides were used for the selective hydrogenation of dienes in hydrocarbons. Subsequently, Wells et al. began a broad screening of transition metal catalysts for the selective hydrogenation of 1,3-butadiene, such as noble metal catalysts like Rh, Pd, Ir, and Pt. Currently, industrially, noble metal Pd-based catalysts are mainly used for catalytic hydrogenation to remove residual 1,3-butadiene from C4 fractions. Although Pd catalysts exhibit high activity, under certain reaction conditions, the selectivity of single-metal Pd catalysts is poor, leading to the easy complete hydrogenation of 1,3-butadiene to butane. Furthermore, the high cost and limited resources of Pd restrict its widespread application. Therefore, the design and development of non-noble metal catalysts has been a research hotspot. Transition metal Ni, due to its low cost and good hydrogenation activity, has been widely used in the selective hydrogenation of unsaturated hydrocarbons. However, Ni-based catalysts exhibit poor selectivity in the hydrogenation reaction of butadiene and are prone to over-hydrogenation to butane, which limits their further industrial application. Therefore, improving the performance of Ni-based catalysts has become a key issue.
[0004] Chinese invention patent CN202311165432.3 discloses a supported catalyst, its preparation method, and its application in the selective hydrogenation of alkynes via electrocatalysis. The catalyst prepared in this invention combines palladium (Pd) with a cerium dioxide (CeO2) support. Due to the strong metal-support interaction (SMSI) effect, the Pd nanoparticles supported on CeO2 exhibit significant catalytic activity in the semi-hydrogenation reaction of alkynes. However, the active metal used in the catalyst preparation in this patent is expensive, which is detrimental to controlling production costs in industrial applications. Furthermore, the stability of the catalyst prepared by this method is not significantly improved, and this catalyst has not been applied to the hydrogenation of butadiene.
[0005] Chinese patent CN201910404239.8 discloses a method for hydrogenating butadiene from C4 components with added regulators. This method employs a two-stage selective hydrogenation process, using palladium as the active catalyst and cobalt, ruthenium, and silver as selective additives. The support is a mixture of alumina, cerium oxide-zirconia, and attapulgite. By controlling the concentration and amount of the regulator H2S, the active components on the catalyst surface are partially deactivated, achieving the desired butadiene hydrogenation to 1-butene with a removal depth of 0.97 ppm, while avoiding excessive side reactions and achieving a 1-butene yield of 100.29%. However, the catalyst in this patent has a multi-component support, making uniform mixing difficult. Furthermore, the two-stage selective hydrogenation process is complex. Additionally, the introduction of H2S as a regulator during catalyst pretreatment can easily lead to catalyst deactivation if not handled properly.
[0006] Chinese invention patent CN202410031002.0 discloses a method for constructing a supported metal catalyst with strong metal-support interaction induced by molten salt, belonging to the field of heterogeneous catalyst preparation technology. The method of this invention includes the following steps: the supported metal catalyst is fully covered with metal salt powder, heated to above the melting point of the metal salt under an inert atmosphere to melt the metal salt powder, and held at this temperature for 0.1–2 hours; after cooling to room temperature, it is washed, centrifuged, and dried sequentially to obtain the supported metal catalyst with strong metal-support interaction induced by molten salt. This invention achieves wide-temperature-range construction of SMSI in oxide-supported metal-based catalyst systems in a low-cost, simple, and efficient manner, and can also expand the application scenarios of SMSI in non-reducing supported catalyst systems. However, the catalyst preparation process of this patent is relatively complex, which is not conducive to practical industrial operation, and this catalyst has not been applied to butadiene hydrogenation.
[0007] Chinese invention patent 202010893526.2 discloses a nickel-based non-precious metal selective hydrogenation catalyst for the selective hydrogenation of 1,3-butadiene from C4 feedstock. The catalyst's active nickel source can be a nickel salt or basic nickel carbonate extracted from spent nickel-metal hydride batteries. A modified attapulgite-montmorillonite composite support is used. The catalyst exhibits good activity and selectivity due to the large specific surface area formed by different channel structures within the crystals of the composite support, the step-like pores formed by the micropores of the aggregates, and the synergistic acid-base catalytic effect. Furthermore, the use of inexpensive raw materials significantly reduces catalyst costs. However, the preparation process of the nickel salt in this patent is relatively complex, has high requirements for raw materials, and excessive loading of the active component can easily lead to agglomeration and increased costs.
[0008] In summary, developing a novel selective hydrogenation catalyst and its preparation method remains one of the urgent problems to be solved in this field. Summary of the Invention
[0009] The purpose of this invention is to provide a method for preparing a supported Ni-based alloy catalyst, which has high activity, good selectivity and stability, and the preparation method is simple and low cost.
[0010] To achieve the above objectives, the present invention provides a method for preparing a supported Ni-based alloy catalyst, comprising the following steps:
[0011] S1, a tungsten compound is dissolved in water and loaded onto an Al2O3 support by impregnation. After aging, drying and calcination in air, an intermediate is obtained.
[0012] S2, a nickel compound is dissolved in water, loaded onto the intermediate by impregnation, aged, dried, calcined in air, and then reduced in a H2 atmosphere to obtain the catalyst.
[0013] The preparation method of the supported Ni-based alloy catalyst of the present invention uses a molar ratio of nickel to tungsten of (0.5-20):1.
[0014] In the preparation method of the supported Ni-based alloy catalyst of the present invention, the mass ratio of nickel compound to alumina is 1:(1.5-4).
[0015] The method for preparing the supported Ni-based alloy catalyst of the present invention involves calcining the Al2O3 support before impregnation, wherein the calcination conditions are calcination at 800-1100℃ for 4-8 hours.
[0016] The preparation method of the supported Ni-based alloy catalyst described in this invention uses an Al2O3 support with a specific surface area of 100-300 m² after calcination. 2 ·g -1 The aperture is 7nm-15nm.
[0017] The preparation method of the supported Ni-based alloy catalyst of the present invention includes a calcination condition of 200-400℃ for 4-8 hours in step S1.
[0018] In the preparation method of the supported Ni-based alloy catalyst of the present invention, the calcination conditions in step S2 are calcination at 300-500℃ for 4-12 hours.
[0019] In the preparation method of the supported Ni-based alloy catalyst of the present invention, the reduction conditions in step S2 are reduction at 300-500℃ for 4-15h.
[0020] The method for preparing the supported Ni-based alloy catalyst of the present invention involves dissolving tungsten and nickel compounds in water under ultrasonic conditions.
[0021] The preparation method of the supported Ni-based alloy catalyst of the present invention includes ultrasonic conditions of 800-1200W power for 0.5-1.5h.
[0022] Beneficial effects of this invention:
[0023] This invention involves first impregnating and air-calcining relatively difficult-to-reduce tungsten metal to form a WO3 support film, followed by impregnation and calcination. Then, H2 is used to reduce relatively easily reduced nickel metal. During H2 reduction, Ni rapidly transforms into metallic particles. During the slow partial reduction of WO3, the SMSI effect between Ni and WO3 causes WO3 to gradually approach and encapsulate Ni particles, thus covering the active sites of Ni participating in side reactions. The core-shell structure formed by this encapsulation significantly improves the catalyst's performance. Hydrogen adsorption and dissociation occur on the Ni surface, and the generated active hydrogen species diffuse to nearby WO3 through a hydrogen spillover effect. Therefore, some WO3 is reduced to W, forming a NiW alloy with Ni. The partially reduced WO3... x The SMSI effect coats Ni particles, thus geometrically modifying their surface. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the formation process of SMSI of Ni and WO3 on Al2O3 support;
[0025] Figure 2 The image shows the HAADF of the Ni-W / Al2O3 catalyst prepared in Example 5.
[0026] Figure 3 The particle size distribution of the Ni-W / Al2O3 catalyst prepared in Example 5;
[0027] Figure 4 HAADF image of the Ni-W / Al2O3 catalyst prepared in Example 1.
[0028] Figure 5 The particle size distribution of the Ni-W / Al2O3 catalyst prepared in Example 1;
[0029] Figure 6 EDS line scan of the Ni-W / Al2O3 catalyst prepared in Example 5;
[0030] Figure 7 EDS line scan of the Ni-W / Al2O3 catalyst prepared in Example 1;
[0031] Figure 8 The lattice fringes of the Ni-W / Al2O3 catalyst prepared in Example 5;
[0032] Figure 9 Selected area electron diffraction of the Ni-W / Al2O3 catalyst prepared in Example 5;
[0033] Figure 10 Performance graphs of the catalysts prepared in Examples 1, 2, 3, 4, 5, and 6;
[0034] Figure 11 Performance graphs of catalysts prepared in Comparative Examples 2, 3, 4, 5, and 6;
[0035] Figure 12 The Ni-W / Al2O3 prepared in Example 5 exhibits long-term stability of 160 hours. Detailed Implementation
[0036] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.
[0037] Table 1
[0038]
[0039] Example 1
[0040] Vector screening:
[0041] Clover-shaped alumina carrier calcined at 800℃ for 6 hours was used, with an average pore size of 7.05 nm and a specific surface area of 268 m². 2 / g. Weigh out 40g of the carrier.
[0042] Catalyst preparation:
[0043] (1) Weigh out 16.75g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 29.1 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 40 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0044] (2) Weigh 17.84g Ni(NO3)2·6H2O, add it to 26.7ml deionized water, disperse it under ultrasonication at 980W for 1 hour, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0045] Catalyst reduction:
[0046] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 300°C for 4 hours using 99.999% pure H2.
[0047] Example 2
[0048] Vector screening:
[0049] Clover-shaped alumina carrier calcined at 900℃ for 8 hours was used, with an average pore size of 8.53 nm and a specific surface area of 204 m². 2 / g. Weigh out 15g of the carrier.
[0050] Catalyst preparation:
[0051] (1) Weigh 2.09g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 10.18 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0052] (2) Weigh 6.69g Ni(NO3)2·6H2O, add it to 9.6ml of deionized water, disperse it under ultrasonication at 980W for 1 hour, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0053] Catalyst reduction:
[0054] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 350°C for 8 hours using 99.999% pure H2.
[0055] Example 3
[0056] Vector screening:
[0057] Clover-shaped alumina carrier calcined at 900℃ for 8 hours was used, with an average pore size of 8.53 nm and a specific surface area of 204 m². 2 / g. Weigh out 15g of the carrier.
[0058] Catalyst preparation:
[0059] (1) Weigh 1.05g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 10.18 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0060] (2) Weigh 6.69g Ni(NO3)2·6H2O, add it to 9.6ml of deionized water, disperse it under ultrasonication at 980W for 1.5 hours, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0061] Catalyst reduction:
[0062] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 500°C for 15 hours using 99.999% pure H2.
[0063] Example 4
[0064] Vector screening:
[0065] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 15g of the carrier.
[0066] Catalyst preparation:
[0067] (1) Weigh 0.79g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 10.18 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0068] (2) Weigh 6.69g Ni(NO3)2·6H2O, add it to 9.66ml of deionized water, disperse it under ultrasonication at 980W for 1.5 hours, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0069] Catalyst reduction:
[0070] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 400°C for 8 hours using 99.999% pure H2.
[0071] Example 5
[0072] Vector screening:
[0073] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 30g of the carrier.
[0074] Catalyst preparation:
[0075] (1) Weigh 1.26g of (NH4)6H2W 12 O 40xH₂O was dissolved in 20.36 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0076] (2) Weigh 13.38g Ni(NO3)2·6H2O, add it to 18.28ml of deionized water, disperse it under ultrasonication at 980W for 1.5 hours, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0077] Catalyst reduction:
[0078] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 450°C for 10 hours using 99.999% pure H2.
[0079] Example 6
[0080] Vector screening:
[0081] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 15g of the carrier.
[0082] Catalyst preparation:
[0083] (1) Weigh 0.31g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 10.18 mL of deionized water, dispersed under ultrasonication at 980 W for 1 hour, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the intermediate catalyst.
[0084] (2) Weigh 6.69g Ni(NO3)2·6H2O, add it to 9.14ml of deionized water, disperse it under ultrasonication at 980W for 1.5 hours, and then load it onto the intermediate catalyst. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain the catalyst.
[0085] Catalyst reduction:
[0086] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 400°C for 4 hours using 99.999% pure H2.
[0087] Comparative Example 1
[0088] Vector screening:
[0089] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 15g of the carrier.
[0090] Catalyst preparation:
[0091] Weigh out 0.84g of (NH4)6H2W 12 O 40 xH₂O was dissolved in 10.18 mL of deionized water, dispersed under ultrasonication at 980 W for 0.5 hours, and then loaded onto a 15 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the catalyst.
[0092] Catalyst reduction:
[0093] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 500°C for 15 hours using 99.999% pure H2.
[0094] Comparative Example 2
[0095] Vector screening:
[0096] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 35g of the carrier.
[0097] Catalyst preparation:
[0098] Weigh 8.67g Ni(NO3)2·6H2O, add it to 23.75ml deionized water, disperse it under ultrasonication at 980W for 0.5 hours, and then load it onto a 35g support that has been calcined at high temperature. After aging for 4 hours, dry it at 120℃ for 4 hours, and then calcine it at 350℃ for 4 hours in air to obtain catalyst A.
[0099] Catalyst reduction:
[0100] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 350°C for 10 hours using 99.999% pure H2.
[0101] Comparative Example 3
[0102] Vector screening:
[0103] The alumina carrier was calcined at 1050℃, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 35g of the carrier.
[0104] Catalyst preparation:
[0105] Weigh 15.6g Ni(NO3)2·6H2O, add it to 23.75ml deionized water, and after ultrasonic dispersion for 1 hour, load it onto a 35g support that has been calcined at high temperature. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain catalyst A.
[0106] Catalyst reduction:
[0107] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 400°C for 15 hours using 99.999% pure H2.
[0108] Comparative Example 4
[0109] Vector screening:
[0110] The alumina carrier was calcined at 1050℃, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 35g of the carrier.
[0111] Catalyst preparation:
[0112] Weigh 22.54g Ni(NO3)2·6H2O, add it to 23.75ml deionized water, and after ultrasonic dispersion for 1 hour, load it onto a 35g support that has been calcined at high temperature. After aging for 4 hours, dry it at 120℃ for 4 hours, and calcine it at 350℃ for 4 hours in air atmosphere to obtain catalyst A.
[0113] Catalyst reduction:
[0114] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 450°C for 10 hours using 99.999% pure H2.
[0115] Comparative Example 5
[0116] Vector screening:
[0117] Clover-shaped alumina carrier calcined at 1050℃ for 4 hours was used, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 40g of the carrier.
[0118] Catalyst preparation:
[0119] Weigh out 17.84g of Ni(NO3)2·6H2O and 0.27g of (NH4)6H2W. 12 O 40·xH2O was impregnated in 27.14 mL of deionized water and dispersed under ultrasonication at 980 W for 1 hour. Then, it was loaded onto a 40 g support that had been calcined at high temperature. After aging for 4 hours, it was dried at 120 °C for 4 hours and calcined at 350 °C for 4 hours in air to obtain the catalyst.
[0120] Catalyst reduction:
[0121] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 450°C for 10 hours using 99.999% pure H2.
[0122] Comparative Example 6
[0123] Vector screening:
[0124] The alumina carrier was calcined at 1050℃, with an average pore size of 12.91 nm and a specific surface area of 132 m². 2 / g. Weigh out 70g of the carrier.
[0125] Catalyst preparation:
[0126] (1) Weigh 31.21 g of Ni(NO3)2·6H2O, dissolve it in 50.7 mL of deionized water, and ultrasonically disperse it for 1.5 hours. Then, load it onto a 15 g support that has been calcined at high temperature. After aging for 4 hours, dry it at 120 °C for 4 hours and calcine it at 350 °C for 4 hours to obtain intermediate catalyst A.
[0127] (2) Weigh 2.65g of (NH4)6H2W 12 O 40 xH2O was added to 44.3 ml of deionized water and ultrasonically dispersed for 1 hour before being loaded onto intermediate catalyst A. After aging for 4 hours, it was dried at 120°C for 4 hours and calcined at 350°C for 4 hours in air to obtain catalyst B.
[0128] Catalyst reduction:
[0129] Before the reaction begins, the sample is placed on a fixed-bed reactor and reduced at 450°C for 10 hours using 99.999% pure H2.
[0130] Figure 1 This is a schematic diagram of the formation process of SMSI between Ni-W alloy and WO3 on an Al2O3 support.
[0131] Figure 2 HAADF image of Ni-W / γ-Al2O3 in Example 5, Figure 3 The particle size distribution of Ni-W / γ-Al2O3 in Example 5 is shown. Figure 4 The image shown is the HAADF image of Ni-W / γ-Al2O3 in Example 1. Figure 5 The particle size distribution of Ni-W / γ-Al2O3 in Example 1 was characterized using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to observe the size and dispersion state of the Ni particles. Figures 2-3 As can be observed, the Ni-W / Al2O3 catalyst prepared in Example 5 has relatively small Ni particles, concentrated between 6-12 nm, with an average particle size of 10.19 nm, and is relatively uniformly dispersed on the Al2O3 support. The Ni-W / Al2O3 catalyst prepared in Example 1 has relatively large Ni particles, concentrated between 10-20 nm, with an average particle size of 15.97 nm.
[0132] Figure 6 , Figure 7 Linear scan energy dispersive spectroscopy (ESD) spectra of the Ni-W / Al2O3 catalysts in Example 5 and Example 1 are shown. The images reveal that in Example 5, the Ni-W / Al2O3 catalyst exhibits stronger W and O signals at the particle periphery and weaker Ni signals, while the Ni signal becomes stronger at the particle center. This indicates that the WO3 formed around the particles under the SMSI effect coats the Ni particles. Due to the addition of a suitable amount of W, bare NiW alloy remains exposed at the particle center. In Example 1, the excessive WO3 almost completely coats the NiW alloy. Strong W and O signals are observed at most locations on the particle periphery and in the center. The excessively strong SMSI effect generated when WO3 modifies the Ni active component leads to excessive WO3 coating of Ni particles, thus covering the active sites and reducing the hydrogenation activity of the Ni-W / Al2O3 catalyst.
[0133] like Figure 8 , Figure 9 The lattice fringes of the Ni-W / Al2O3 catalyst in Example 5 were measured by selected electron diffraction, and the lattice fringes spacing of the Ni-W / Al2O3 catalyst was 0.209 nm. According to literature reports, the lattice fringes of W(110) are 0.222 nm and the lattice fringes of Ni(111) are 0.203 nm. The lattice fringes spacing of Ni-W is within the range of the lattice fringes of W(110) and Ni(111), indicating that the formation of NiW alloy is related to the lattice fringes spacing. Figure 9 As shown by selected area electron diffraction, the addition of a small amount of W to the Ni-W / Al2O3 catalyst did not change the crystal form of Ni, indicating that W was uniformly dispersed in the Ni lattice at this time.
[0134] Catalyst performance evaluation results are as follows Figure 10 , Figure 11As shown. S1, S2, S3, S4, S5, and S6 are catalysts prepared in Examples 1, 2, 3, 4, 5, and 6, respectively; Z1, Z2, Z3, Z4, and Z5 are catalysts prepared in Comparative Examples 2, 3, 4, 5, and 6, respectively. Comparative Example 1 does not exhibit catalytic activity. It can be observed that under the investigated reaction conditions, the butene yield exhibits a "volcano-shaped" curve trend. The catalyst performance test results indicate that when the NiW metal molar ratio is 10:1, after preparation via stepwise impregnation, a catalyst is formed between Ni and WO3 as shown in the figure. Figure 1 The SMSI effect shown indicates that WO3 coats Ni, geometrically modifying the surface of the NiW particles. However, WO3 does not completely coat the NiW alloy; the active sites on the Ni particle surface that selectively hydrogenate butadiene still participate in the reaction, increasing the selectivity of the NiW catalyst and leading to a higher butene yield. When excessive W is added, an overly strong SMSI effect may occur, causing WO3 to excessively coat the Ni particles, thus covering most of the Ni's active sites and degrading catalyst performance.
[0135] like Figure 12 In Example 5, the Ni-W / Al2O3 catalyst underwent a 160-hour long-term stability evaluation test. During the evaluation period, the catalyst exhibited good stability, with a butadiene conversion of 100%, a butene yield consistently around 95%, and an average butane increment of 2.22%. Due to the SMSI effect, WO3 partially coated the surface of the NiW alloy, forming a layer resembling... Figure 1 The core-shell structure shown improves catalyst stability. Furthermore, studies have shown that the addition of a second metal dilutes the surface aggregation of Ni metal atoms, inhibiting carbon deposition and significantly extending catalyst lifetime.
[0136] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing a supported Ni-based alloy catalyst, characterized in that, Includes the following steps: S1, a tungsten compound is dissolved in water and loaded onto an Al2O3 support by impregnation. After aging, drying and calcination in air, an intermediate is obtained. S2, a nickel compound is dissolved in water, loaded onto the intermediate by impregnation, aged, dried, calcined in air, and then reduced in a H2 atmosphere to obtain the catalyst.
2. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The molar ratio of nickel to tungsten is (0.5-20):
1.
3. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The mass ratio of nickel compound to aluminum oxide is 1:(1.5-4).
4. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The Al2O3 support is calcined before impregnation, and the calcination conditions are calcination at 800-1100℃ for 4-8 hours.
5. The method for preparing the supported Ni-based alloy catalyst according to claim 4, characterized in that, The specific surface area of the calcined Al2O3 support is 100-300 m². 2 ·g -1 The aperture is 7nm-15nm.
6. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The calcination conditions in step S1 are 200-400℃ for 4-8 hours.
7. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The calcination conditions in step S2 are 300-500℃ for 4-12 hours.
8. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, The reduction conditions in step S2 are reduction at 300-500℃ for 4-15 hours.
9. The method for preparing the supported Ni-based alloy catalyst according to claim 1, characterized in that, Tungsten and nickel compounds dissolve in water under ultrasonic conditions.
10. The method for preparing the supported Ni-based alloy catalyst according to claim 9, characterized in that, The ultrasonic conditions are 800-1200W power and 0.5-1.5h.