Metal-modified supported nickel-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal-modified supported nickel-based catalyst as well as a preparation method and application thereof. According to the invention, copper or cobalt is introduced into the supported nickel-based catalyst for modification, and the obtained metal modified supported nickel-based catalyst can efficiently catalyze hydrogenation to synthesize hexamethylenediamine under relatively mild conditions, and shows high selectivity and high stability.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a metal-modified supported nickel-based catalyst and a preparation method and application thereof. Background Art

[0002] Hexamethylenediamine is used in many fields as a raw material for preparing polyamide. Hexamethylenediamine can also be used as a crosslinking agent and curing agent for the production of materials such as urea-formaldehyde resin and epoxy resin. It is an important organic chemical raw material. The global market demand for hexamethylenediamine is huge, and companies in various countries have added production sites in various regions to expand production capacity. In industry, hexamethylenediamine is prepared by hydrogenation of adiponitrile, which is divided into two processes: high-pressure method and low-pressure method. Among them, the high-pressure method uses active metal copper or iron as a catalyst, and reacts at a pressure greater than 30MPa. The product selectivity is high, but the operating conditions are strict, the production safety requirements are high, and the equipment investment is large. The low-pressure method uses cobalt or nickel metal skeleton catalysts, the reaction pressure is usually below 3MPa, the operating conditions are mild, but the catalyst is easy to break, and the by-product selectivity is high. In industry, ammonia or strong alkali is added to the reaction system to suppress the generation of by-products, but it will increase the difficulty of subsequent product separation.

[0003] In the industrial production of hexamethylenediamine, catalysts play a vital role. The preparation of catalysts with high activity and high selectivity is an urgent problem to be solved in the production process of hexamethylenediamine. Supported catalysts have the advantages of high reactivity, good dispersibility, and high stability. They are the main target of current research. There are many reports on supported catalysts for adiponitrile hydrogenation, but the related catalysts still have obvious shortcomings. For example, the catalyst uses precious metal materials, which has high production costs; the use of intermittent reaction devices cannot achieve continuous production; in order to achieve higher selectivity, the reaction conditions are harsh, etc. Therefore, it is necessary to provide a catalyst with high selectivity and high stability, which can efficiently catalyze hydrogenation to synthesize hexamethylenediamine under relatively mild conditions. Summary of the invention

[0004] The present application provides a metal-modified supported nickel-based catalyst and a preparation method and application thereof, which can efficiently catalyze hydrogenation to synthesize hexamethylenediamine under relatively mild conditions and exhibit high selectivity and high stability.

[0005] In a first aspect, the present invention provides a method for preparing a metal-modified supported nickel-based catalyst, comprising the following steps:

[0006] (1) drying the aluminum oxide to remove water in the pores of the aluminum oxide to obtain a carrier;

[0007] (2) dissolving a metal salt in deionized water to obtain a metal salt solution, wherein the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and cobalt nitrate, or the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and copper nitrate;

[0008] (3) After mixing the carrier obtained in step (1) and the metal salt solution obtained in step (2), ultrasonic treatment and drying are performed, and the dried mixture is calcined to obtain the metal-modified supported nickel-based catalyst.

[0009] In some embodiments, the preparation method of aluminum oxide in step (1) includes: using a co-precipitation method, dissolving aluminum nitrate and sodium carbonate in deionized water, and adding them dropwise into a reaction container for precipitation, with the end point pH being between 6.0 and 9.0, and then filtering, washing, drying, calcining, and grinding to obtain the aluminum oxide.

[0010] In some embodiments, the ultrasonic frequency in step (3) is 20-100 kHz, and the ultrasonic treatment time is 1-5 h; the drying temperature is 90-150° C., and the drying time is 6-24 h; the roasting temperature is 500-800° C., and the roasting temperature is 2-6 h.

[0011] In the second aspect, an embodiment of the present application provides a metal-modified supported nickel-based catalyst prepared by any of the above-mentioned methods for preparing a metal-modified supported nickel-based catalyst, wherein the metal-modified supported nickel-based catalyst comprises a supported nickel-based catalyst and a modified metal, wherein the supported nickel-based catalyst comprises an alumina carrier, and nickel, iron and sodium supported on the alumina carrier, wherein the nickel, iron and sodium exist in the form of metal oxides, the modified metal is one of copper or cobalt, and the modified metal is supported on the alumina carrier.

[0012] In some embodiments, the mass of the modified metal accounts for 2.0%-5.0% of the total mass of the catalyst, based on mass percentage.

[0013] In a third aspect, an embodiment of the present application provides an application of a metal-modified supported nickel-based catalyst in the hydrogenation of adiponitrile to prepare hexamethylenediamine, comprising the following steps: using a mixed solution of adiponitrile and ethanol as a reaction raw material, wherein the mass fraction of adiponitrile in the reaction raw material is 5-40%, adding the metal-modified supported nickel-based catalyst into the constant temperature section of a fixed bed reactor, filling quartz sand and quartz wool at the upper and lower parts of the metal-modified supported nickel-based catalyst, and conveying the reaction raw material into the fixed bed reactor for reaction to obtain hexamethylenediamine.

[0014] In some embodiments, the mass space velocity of the reaction raw materials is 1h -1 -3h -1 .

[0015] In some embodiments, the reaction pressure in the fixed bed reactor is 2 MPa-3 MPa.

[0016] In some embodiments, the reaction temperature in the fixed bed reactor is between 90°C and 115°C.

[0017] In some embodiments, the molar ratio of hydrogen to nitrile during the reaction is 10-20.

[0018] It can be seen from the above technical scheme that the present specification provides a metal-modified supported nickel-based catalyst, which can efficiently catalyze hydrogenation to synthesize hexamethylenediamine under relatively mild conditions and exhibits high selectivity and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 The adsorption and desorption curves of commercial activated alumina and homemade alumina provided by the present application are shown;

[0021] Figure 2 The pore size distribution diagram of commercial activated alumina and homemade alumina provided by the present application is shown;

[0022] Figure 3 The X-ray diffraction patterns of the catalysts of some embodiments and comparative examples provided in this application are shown;

[0023] Figure 4A The X-ray photoelectron spectrum of the catalyst corresponding to Example 1 of the present application is shown;

[0024] Figure 4B The X-ray photoelectron spectrum of the catalyst corresponding to Example 4 of the present application is shown;

[0025] Figure 4C The X-ray photoelectron spectrum of the catalyst corresponding to Comparative Example 1 of the present application is shown;

[0026] Figure 4D The X-ray photoelectron spectrum of the catalyst corresponding to Comparative Example 2 of the present application is shown;

[0027] Figure 4E The X-ray photoelectron spectrum of the catalyst corresponding to Comparative Example 3 of the present application is shown;

[0028] Figure 4FThe X-ray photoelectron spectrum of the catalyst corresponding to Comparative Example 4 of the present application is shown. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of this specification, the specification will be described more fully below with reference to the relevant drawings. The preferred embodiments of this specification are given in the drawings. However, this specification can be implemented in many different forms without departing from the core spirit of this specification and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of this specification more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this specification belongs. The terms used herein in this specification are only for the purpose of describing specific embodiments and are not intended to limit this specification. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] In a first aspect, the present invention provides a method for preparing a metal-modified supported nickel-based catalyst, comprising the following steps:

[0032] (1) drying the aluminum oxide to remove water in the pores of the aluminum oxide to obtain a carrier;

[0033] (2) dissolving a metal salt in deionized water to obtain a metal salt solution, wherein the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and cobalt nitrate, or the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and copper nitrate;

[0034] (3) The carrier obtained in step (1) and the metal salt solution obtained in step (2) are mixed, ultrasonicated and dried, and the dried mixture is calcined to obtain a metal-modified supported nickel-based catalyst.

[0035] The catalyst preparation method provided in the embodiment of the present application adopts an impregnation method to synthesize a metal-modified supported nickel-based catalyst, wherein Al2O3 is used as a carrier, and Ni, Na, Fe and other active metals (Cu or Co) are introduced. The catalyst preparation process is simple to operate, and the prepared catalyst has high mechanical strength and good stability. Since Cu or Co is introduced into the catalyst system for modification, the prepared catalyst can exhibit good catalyst performance and stability.

[0036] In some embodiments, the preparation method of aluminum oxide in step (1) includes: using a coprecipitation method, dissolving aluminum nitrate and sodium carbonate in deionized water, adding them dropwise to a reaction vessel for precipitation, and filtering, washing, drying, calcining, and grinding to obtain the aluminum oxide. In the embodiments of the present application, aluminum oxide can be directly used as a commercial activated alumina carrier, or a coprecipitation method can be used to prepare a homemade alumina carrier. The inventors have found through a large number of experiments that the catalyst prepared by using a homemade alumina carrier using the coprecipitation method can load more active metals, thereby improving the catalyst performance.

[0037] In some embodiments, the ultrasonic frequency in step (3) is 20-100 kHz, and the ultrasonic treatment time is 1-5 h; the drying temperature is 90-150° C., and the drying time is 6-24 h; the calcination temperature is 500-800° C., and the calcination temperature is 2-6 h.

[0038] In the second aspect, the embodiments of the present application provide a metal-modified supported nickel-based catalyst prepared by any of the above-mentioned methods for preparing a metal-modified supported nickel-based catalyst. The metal-modified supported nickel-based catalyst provided in the embodiments of the present application includes a supported nickel-based catalyst and a modified metal, wherein the supported nickel-based catalyst includes an alumina carrier, and nickel, iron and sodium supported on the alumina carrier, the nickel, iron and sodium exist in the form of metal oxides, the modified metal is one of copper or cobalt, and the modified metal is supported on the alumina carrier.

[0039] In some embodiments, the mass of the modified metal accounts for 2.0%-5.0% of the total mass of the catalyst in terms of mass percentage. The inventors have found through a large number of experiments that the amount of modified metal added to the catalyst has a great influence on the performance of the catalyst. When the amount of modified metal added to the catalyst is within the mass percentage range of 2.0%-5.0%, excellent catalytic performance can be exhibited.

[0040] In a third aspect, an embodiment of the present application provides an application of a metal-modified supported nickel-based catalyst in the hydrogenation of adiponitrile to prepare hexamethylenediamine, comprising the following steps: using a mixed solution of adiponitrile and ethanol as a reaction raw material, wherein the mass fraction of adiponitrile in the reaction raw material is 5-40%, adding a metal-modified supported nickel-based catalyst to the constant temperature section of a fixed bed reactor, filling quartz sand and quartz wool at the upper and lower parts of the metal-modified supported nickel-based catalyst, and conveying the reaction raw material into the fixed bed reactor for reaction to obtain hexamethylenediamine.

[0041] In some embodiments, the mass space velocity of the reaction raw materials is 1h -1 -3h -1 .

[0042] The inventors have found through a large number of experiments that when a metal-modified supported nickel-based catalyst is used in a fixed bed reactor to hydrogenate adiponitrile to prepare hexamethylenediamine, the selectivity of hexamethylenediamine varies under different reaction conditions. Among them, the mass space velocity of the reaction raw materials has a great influence on the selectivity of hexamethylenediamine. During the reaction, the mass space velocity of the reaction raw materials is controlled at 1h -1 -3h -1 (e.g. 1h -1 , 1.5h -1 , 2h -1 , 2.5h -1 , 3h -1 or any value between any two of the above mass space velocities), the selectivity of hexamethylenediamine can reach a higher level.

[0043] In some embodiments, the reaction pressure in the fixed bed reactor is 2 MPa-3 MPa.

[0044] The inventor has found through a large number of experiments that when a metal-modified supported nickel-based catalyst is used in a fixed-bed reactor to hydrogenate adiponitrile to prepare hexamethylenediamine, the reaction pressure in the fixed-bed reactor also has a greater influence on the selectivity of hexamethylenediamine. During the reaction, the reaction pressure in the fixed-bed reactor can be controlled within the range of 2MPa-3MPa to improve the selectivity of hexamethylenediamine. For example, the reaction pressure in the fixed-bed reactor can be 2.0MPa, 2.1MPa, 2.2MPa, 2.3MPa, 2.4MPa, 2.5MPa, 2.6MPa, 2.7MPa, 2.8MPa, 2.9MPa, 3MPa, or any value between any two of the above reaction pressure values.

[0045] In some embodiments, the reaction temperature in the fixed bed reactor is between 90°C and 115°C.

[0046] The inventors have found through a large number of experiments that when a reaction of preparing hexamethylenediamine by hydrogenating adiponitrile using a metal-modified supported nickel-based catalyst in a fixed bed reactor is carried out, the reaction temperature in the fixed bed reactor also has a great influence on the selectivity of hexamethylenediamine. When the reaction temperature in the fixed bed reactor is between 90°C and 115°C, a higher selectivity of hexamethylenediamine can be achieved. For example, the reaction temperature in the fixed bed reactor can be controlled at 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or any value between any two of the above temperature values.

[0047] In some embodiments, the molar ratio of hydrogen to nitrile during the reaction is 10-20.

[0048] The inventors have found through a large number of experiments that when a reaction of preparing hexamethylenediamine by hydrogenating adiponitrile using a metal-modified supported nickel-based catalyst in a fixed bed reactor is carried out, the hydrogen-nitrile molar ratio in the reaction process also has a great influence on the selectivity of hexamethylenediamine. When the hydrogen-nitrile molar ratio is 10-20, for example, it can be 10, 12, 14, 16, 18, 20, or any ratio between any two of the above molar ratios, a higher selectivity for hexamethylenediamine can be achieved.

[0049] The following are specific preparation examples related to the above content of the present disclosure. It should be clear that the following examples are only for illustrating the metal-modified supported nickel-based catalyst disclosed above and its preparation method and application, and the specific implementation methods and parameters used therein are only one or several methods in accordance with the numerous processes and methods described above. Those skilled in the art can use other parameters according to the content introduced in this specification to prepare metal-modified supported nickel-based catalysts according to the above method without deviating from the core spirit disclosed in the application.

[0050] Example 1

[0051] The present embodiment provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 0.5672 g Cu(NO3)2·3H2O, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.45 g of a commercial activated alumina carrier after drying (purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with a brand name of A800251), and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and grinding and screening to obtain a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh, denoted as Ni 0.2 Fe 0.05 Na2O 0.15 Cu 0.025 / Al2O3-1.

[0052] like Figure 1 , Figure 2 As shown, the commercial activated alumina exhibits a type IV isotherm, with obvious desorption hysteresis and pore size distribution within the mesoporous range, wherein the hysteresis loop type of the commercial activated alumina is H2. Table 1 shows the structural parameters of the commercial activated alumina of Example 1 and the homemade alumina of Example 2. The commercial activated alumina carriers used in the examples and comparative examples of the present application were purchased from the same manufacturer and had the same brand.

[0053] Table 1. Structural parameters of different alumina supports

[0054]

[0055] like Figure 3 As shown, the metal-modified supported nickel-based catalyst provided in this embodiment contains NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures. Cu is not shown in the XRD diagram due to its low content.

[0056] Example 2

[0057] The present embodiment provides an alumina carrier, and its preparation method includes: using a co-precipitation method, dissolving appropriate amounts of Al(NO3)3·9H2O and Na2CO3 in deionized water, and adding them dropwise into a beaker for precipitation, with the end point pH being between 6.0 and 9.0, and then filtering, washing, drying, calcining, and grinding to obtain an alumina carrier for impregnation. Before use, the alumina carrier is placed in an oven to dry overnight to remove moisture in the alumina pores.

[0058] The present embodiment also provides a metal-modified supported nickel-based catalyst, and its preparation method comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 0.5672 g Cu(NO3)2·3H2O, and stirring and mixing them to obtain a metal salt solution; taking 3.45 g of a homemade alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating it for 3 hours, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 hours, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is recorded as Ni 0.2 Fe 0.05 Na2O 0.15 Cu 0.025 / Al2O3-2.

[0059] like Figure 1 , Figure 2 As shown in the figure, the self-made alumina by co-precipitation method showed type IV isotherm, with obvious desorption hysteresis and pore size distribution within the mesoporous range. Among them, the hysteresis loop type of the self-made alumina was H3, indicating that the self-made alumina was a layered aggregate with more macropores in the pore structure, which could fully load the active metal during the impregnation process and improve the catalyst performance.

[0060] Example 3

[0061] The present embodiment provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 1.1344 g Cu(NO3)2·6H2O, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.3 g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is recorded as Ni 0.2 Fe 0.05 Na2O 0.15 Cu 0.05 / Al2O3.

[0062] Example 4

[0063] The present embodiment provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 0.74 g Co(NO3)2·6H2O, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.45 g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is denoted as Ni 0.2 Fe 0.05 Na2O 0.15 Co 0.025 / Al2O3.

[0064] like Figure 3 As shown, the catalyst contains NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures. Co is not shown in the XRD diagram due to its low content.

[0065] Comparative Example 1

[0066] The present comparative example provides a supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25°C, taking an appropriate amount of deionized water to dissolve 5.9186g Ni(NO3)2·6H2O, 2.1643g Fe(NO3)3·9H2O and 2.4677g NaNO3, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.6g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating it for 3h, and then drying the mixture in an oven at 110°C overnight, and then calcining it in a muffle furnace at 500°C for 6h, and obtaining a supported nickel-based catalyst with Al2O3 as a carrier with a particle size of 40-60 mesh after grinding and screening, wherein the supported nickel-based catalyst is a supported Ni-based catalyst modified by Na and Fe, and is denoted as Ni 0.2 Fe 0.05 Na2O 0.15 / Al2O3.

[0067] like Figure 3 As shown, the catalyst contains both NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures.

[0068] Comparative Example 2

[0069] The present comparative example provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 1.0823 g NH4ReO4, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.45 g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is recorded as Ni 0.2 Fe 0.05 Na2O 0.15 Re 0.025 / Al2O3.

[0070] like Figure 3 As shown, the catalyst contains NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures. Re is not shown in the XRD diagram due to its low content.

[0071] Comparative Example 3

[0072] The present comparative example provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 0.96 g Mg(NO3)2·6H2O, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.45 g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is recorded as Ni 0.2 Fe 0.05 Na2O 0.15 MgO 0.025 / Al2O3.

[0073] like Figure 3 As shown, the catalyst contains NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures. Mg is not shown in the XRD diagram due to its low content.

[0074] Comparative Example 4

[0075] The present comparative example provides a metal-modified supported nickel-based catalyst, and the preparation method thereof comprises the following steps: at 25° C., taking an appropriate amount of deionized water to dissolve 5.9186 g Ni(NO3)2·6H2O, 2.1643 g Fe(NO3)3·9H2O, 2.4677 g NaNO3 and 0.6854 g Zn(NO3)2·6H2O, and stirring and mixing them thoroughly to obtain a metal salt solution; taking 3.45 g of a commercial activated alumina carrier after drying, and mixing it evenly with the metal salt solution and placing it in a quartz crucible; ultrasonically treating the mixture for 3 h, and then drying the mixture in an oven at 110° C. overnight, and then calcining it in a muffle furnace at 500° C. for 6 h, and obtaining a metal-modified supported nickel-based catalyst with a particle size of 40-60 mesh after grinding and screening, which is recorded as Ni 0.2 Fe 0.05 Na2O 0.15 Zn 0.025 / Al2O3.

[0076] like Figure 3 As shown, the catalyst contains NiAl2O4 and NiFe2O4 spinel structures as well as independent Na2O and Al2O3 crystal structures. Zn is not shown in the XRD diagram due to its low content.

[0077] The catalysts of some embodiments and comparative examples were subjected to X-ray photoelectron spectroscopy analysis. Figure 4A-4F The X-ray photoelectron spectra of the catalysts of some embodiments and comparative examples are shown. Table 2 shows the valence distribution and proportion relationship of the Ni element in the catalysts of some embodiments and comparative examples.

[0078] Table 2. Valence distribution and ratio of Ni element in the catalysts of some examples and comparative examples

[0079]

[0080] Combination Figure 4A-4F , and Table 2 shows that the active species Ni 0 The content of Ni directly reflects the catalyst performance. The addition of Cu and Co modified catalysts 0 The higher the content, the better the catalyst performance. Adding Re and Zn modified catalyst Ni 0 The content decreased slightly, while the addition of Mg-modified catalyst Ni 0 The content decreased significantly.

[0081] Test Example 1

[0082] In this test example, the catalysts of Examples 1-4 and Comparative Examples 1-4 are used to catalyze the hydrogenation of adiponitrile to prepare hexamethylenediamine, comprising the following steps: adding the catalyst into a fixed bed reactor, filling quartz wool and quartz sand at the upper and lower ends of the catalyst so that the catalyst is located in a constant temperature zone, the reaction raw material is an ethanol solution with a mass fraction of 10% adiponitrile, the raw material liquid is transported into the reactor by a horizontal flow pump, and the raw material mass space velocity is 2h -1 , hydrogen nitrile molar ratio 15, reaction pressure maintained at 3MPa, reaction temperature 110°C, sampling once every 2h, and quantitative analysis by chromatography. The experimental results are shown in Table 3 below.

[0083] Table 3. Catalytic reaction results of Examples 1-4 and Comparative Examples 1-4

[0084]

[0085] According to the above experimental results, the catalysts modified by Cu and Co have higher catalytic performance and higher stability, the catalyst modified by Zn has improved stability, the catalyst modified by Mg has no significant change, and the performance of the catalyst modified by Re has decreased. The peak height corresponding to the active component of the catalyst modified by Re in the XRD graph is significantly lower than that of other catalysts. The higher the peak height, the higher the crystallinity of the corresponding component. Therefore, the decrease in the activity of the catalyst modified by Re may be related to the decrease in the crystallinity of the active metal on the catalyst.

[0086] Since the active species Ni 0 The content of Ni can directly reflect the catalyst performance. The addition of Cu and Co modified catalysts0 The higher the content, the better the catalyst performance. The catalyst Ni modified by adding Zn 0 The content decreased slightly, and the performance did not change significantly, while the addition of Mg-modified catalyst Ni 0 The content decreased significantly, the catalyst performance also decreased, and the intermediate product aminocapronitrile appeared, indicating that the hydrogenation performance of the catalyst decreased.

[0087] Compared with commercial alumina, the catalyst prepared using homemade alumina as a carrier has significantly improved catalyst performance and stability for catalyzing the hydrogenation of adiponitrile to produce hexamethylenediamine.

[0088] The Cu content in the catalyst of Example 3 is relatively high, and the corresponding catalytic performance and stability are significantly reduced, indicating that the Cu content in the catalyst needs to be controlled within an appropriate range to exhibit good catalytic performance.

[0089] Test Example 2

[0090] This test example adopts the metal-modified supported nickel-based catalyst prepared in Example 1, and applies it to catalyze the hydrogenation of adiponitrile to prepare hexamethylenediamine, comprising the following steps: adding a catalyst into a fixed bed reactor, filling quartz wool and quartz sand at both the upper and lower ends of the catalyst so that the catalyst position falls in the constant temperature zone, the reaction raw material is an ethanol solution of adiponitrile with a mass fraction of 10%, and the raw material liquid is transported into the reactor by a horizontal flow pump for reaction. This test example continues to investigate the influence of different experimental conditions (such as the mass space velocity of the reaction raw material, reaction pressure, reaction temperature, hydrogen nitrile molar ratio) on the catalytic reaction results during the catalytic reaction. Table 4 shows different reaction control conditions, and Table 5 shows the corresponding experimental results under each condition.

[0091] Table 4. Details of experimental conditions

[0092] serial number Raw material mass space velocity Reaction pressure Reaction temperature Hydronitrile molar ratio 1# <![CDATA[2h -1 ]]> 3MPa 110℃ 15 2# <![CDATA[4h -1 ]]> 3MPa 110℃ 15 3# <![CDATA[2h -1 ]]> 4MPa 110℃ 15 4# <![CDATA[2h -1 ]]> 3MPa 120℃ 15 5# <![CDATA[2h -1 ]]> 3MPa 110℃ 25

[0093] Table 5. Catalytic reaction results corresponding to various reaction conditions

[0094]

[0095]

[0096] It can be seen from Table 4 and Table 5 that for the same metal-modified supported nickel-based catalyst, when it is used in the process of catalyzing the hydrogenation of adiponitrile to prepare hexamethylenediamine, different reaction conditions will affect the catalytic results. The optimal conditions confirmed by experimental comparison are as follows: reaction pressure 3MPa, reaction temperature 110℃, raw material mass space velocity 3h -1 , hydrogen nitrile molar ratio is 15.

[0097] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above-described embodiments only express several embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A method for preparing a metal-modified supported nickel-based catalyst, characterized in that: The following steps are involved: (1) drying the aluminum oxide to remove water in the pores of the aluminum oxide to obtain a carrier; (2) dissolving a metal salt in deionized water to obtain a metal salt solution, wherein the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and cobalt nitrate, or the metal salt comprises nickel nitrate, iron nitrate, sodium nitrate and copper nitrate; (3) After mixing the carrier obtained in step (1) and the metal salt solution obtained in step (2), ultrasonic treatment and drying are performed, and the dried mixture is calcined to obtain the metal-modified supported nickel-based catalyst.

2. The method for preparing a metal-modified supported nickel-based catalyst according to claim 1, wherein: The preparation method of aluminum oxide in step (1) comprises: using a co-precipitation method, dissolving aluminum nitrate and sodium carbonate in deionized water, and adding them dropwise into a reaction container for precipitation, wherein the end point pH is between 6.0 and 9.0, and then filtering, washing, drying, calcining, and grinding to obtain the aluminum oxide.

3. The method for preparing a metal-modified supported nickel-based catalyst according to claim 1, wherein: The ultrasonic frequency in step (3) is 20-100kHz, and the ultrasonic treatment time is 1-5h; the drying temperature is 90-150°C, and the drying time is 6-24h; the roasting temperature is 500-800°C, and the roasting temperature is 2-6h.

4. The metal-modified supported nickel-based catalyst prepared by the method for preparing the metal-modified supported nickel-based catalyst according to any one of claims 1 to 3, characterized in that: The invention comprises a supported nickel-based catalyst and a modified metal. The supported nickel-based catalyst comprises an aluminum oxide carrier, and nickel, iron and sodium supported on the aluminum oxide carrier. The nickel, iron and sodium exist in the form of metal oxides. The modified metal is one of copper or cobalt, and the modified metal is supported on the aluminum oxide carrier.

5. The metal-modified supported nickel-based catalyst according to claim 4, characterized in that Calculated by mass percentage, the mass of the modified metal accounts for 2.0%-5.0% of the total mass of the catalyst.

6. Use of the metal-modified supported nickel-based catalyst as claimed in claim 4 or 5 in the hydrogenation of adiponitrile to prepare hexamethylenediamine, characterized in that: The method comprises the following steps: using a mixed solution of adiponitrile and ethanol as a reaction raw material, wherein the mass fraction of adiponitrile in the reaction raw material is 5-40%, adding the metal-modified supported nickel-based catalyst into a constant temperature section of a fixed bed reactor, filling quartz sand and quartz wool at the upper and lower parts of the metal-modified supported nickel-based catalyst, and conveying the reaction raw material into the fixed bed reactor for reaction to obtain hexamethylenediamine.

7. Use of the metal-modified supported nickel-based catalyst according to claim 6 in the hydrogenation of adiponitrile to prepare hexamethylenediamine, characterized in that: The mass space velocity of the reaction raw materials is 1h -1 -3h -1 .

8. Use of the metal-modified supported nickel-based catalyst according to claim 6 in the hydrogenation of adiponitrile to prepare hexamethylenediamine, characterized in that: The reaction pressure in the fixed bed reactor is 2MPa-3MPa.

9. Use of the metal-modified supported nickel-based catalyst according to claim 6 in the hydrogenation of adiponitrile to prepare hexamethylenediamine, characterized in that: The reaction temperature in the fixed bed reactor is between 90°C and 115°C.

10. Use of the metal-modified supported nickel-based catalyst according to claim 6 in the hydrogenation of adiponitrile to prepare hexamethylenediamine, characterized in that: The molar ratio of hydrogen to nitrile during the reaction is 10-20.

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