Supported catalysts, methods for their preparation and use

Abstract

The application relates to the technical field of catalysts, in particular to a supported catalyst and a preparation method and application thereof. The supported catalyst comprises a carrier and an active component supported on the carrier; wherein the carrier is silicon-modified alumina with a B acid density of less than or equal to 2 micromoles per gram; the dispersity of the active component is greater than or equal to 20 percent; wherein the content of the carrier is 90-99.9 percent by weight and the content of the active component is 0.1-10 percent by weight based on the total weight of the supported catalyst. The supported catalyst provided by the application has high catalytic activity and selectivity; meanwhile, the method provided by the application simplifies the process flow and is convenient for industrial production.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a supported catalyst, its preparation method, and its application. Background Technology

[0002] Supported metal catalysts are a widely used class of catalysts in industry. Their high activity, high selectivity, and long service life have led to significant development in recent years. However, the realization of industrial catalytic hydrogenation, catalytic oxidation, and catalytic reforming processes not only requires catalysts with excellent metal and support components, but also places high demands on the catalyst's shape and the active sites and surface properties it possesses after shaping.

[0003] CN201911299506.6 discloses a method for modifying an alumina support using a silicon-containing solution. This method can improve the pore size distribution of the support, adjust the acidity of the catalyst, and enhance the interaction between the active component of the catalyst and the support. This method is applicable to the preparation of catalysts for hydrodemetallization, hydrodesulfurization, and hydroconversion.

[0004] CN201610767038.0 discloses a silicon-modified Fischer-Tropsch synthesis catalyst and its application. The catalyst synthesized using this silicon modification method exhibits superior catalytic activity, stability, and wear resistance in the Fischer-Tropsch reaction.

[0005] CN201610915896.5 discloses a silicon-zinc modified catalyst support, its preparation method, and its application. This method involves contacting one or more modified silicone oils and water-soluble zinc compounds with an alumina support to control the surface acidity and acid strength of the support, thereby making it a support with higher activity for hydrogenation catalysts.

[0006] In the production of fine chemicals, some reactants (amides, esters, acyl chlorides, etc.) have specific requirements for the acidity of the catalyst surface. However, current research and development of industrial-grade catalysts pays little attention to the control of the microscopic properties of the catalyst surface. This results in slow progress in the research and development of fine chemicals and limits the application of many catalysts with rich acid-base properties on their surfaces. To address the production and research of these fine chemicals, it is necessary to construct molded catalysts with special surface properties by combining the structural properties of the reactants and products. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned defects and provide a supported catalyst, its preparation method, and its application. This supported catalyst uses silica-modified alumina with low Brønsted acid density as a support, combined with active components of specific dispersion and content, to achieve high catalytic activity and selectivity. Furthermore, using this supported catalyst to catalyze the synthesis of lysine-type antibacterial monomers, the aminoalkylation reaction of aromatic amines, and the preparation of amide derivatives can effectively improve the yield of the target products.

[0008] To achieve the above objectives, a first aspect of the present invention provides a supported catalyst, the supported catalyst comprising: a support and an active component supported on the support;

[0009] Wherein, the carrier is silicon-modified alumina with a Brønsted acid density ≤ 2 μmol / g; the dispersion of the active component is ≥ 20%;

[0010] Wherein, based on the total weight of the supported catalyst, the content of the support is 90-99.9 wt%, and the content of the active component is 0.1-10 wt%.

[0011] Preferably, the active component is selected from at least one of Pt, Pd, Rh, Ir, Ru and Ni.

[0012] Preferably, the silicon-modified alumina comprises silicon and alumina, wherein the silicon-to-alumina ratio of the silicon-modified alumina is <1, the silicon is connected to the surface of the alumina by Si-O-Al chemical bonds, and adjacent silicon atoms on the surface of the alumina are connected by Si-O-Si chemical bonds.

[0013] Preferably, based on the total weight of the silicon-modified alumina, the alumina content is 50-90 wt%; with SiO2 as the main component. x The silicon content is calculated to be 10-50 wt%, wherein 1 ≤ x ≤ 2.

[0014] A second aspect of the present invention provides a method for preparing a supported catalyst, the method comprising the following steps:

[0015] (1) The aluminum source, the acidic compound and water are mixed in a first mixture to obtain a first mixture;

[0016] (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain molded alumina;

[0017] (3) Dissolve the shaped alumina in water, first add an alkaline compound to adjust the pH to 7-12, then add a silicon source for a second mixing to obtain a second mixture;

[0018] (4) The second mixture is subjected to solid-liquid separation, and the obtained silicon-modified alumina precursor is subjected to second drying and second calcination in sequence, and the obtained silicon-modified alumina is used as a carrier.

[0019] (5) A soluble metal salt is loaded onto the surface of the support, and the resulting catalyst precursor is subjected to a third drying and a third calcination to obtain a supported catalyst.

[0020] The third aspect of this invention provides a supported catalyst provided in the first aspect, or a supported catalyst prepared by the method provided in the second aspect, for use in the catalytic synthesis of lysine-type antibacterial monomers, the aminoalkylation reaction of aromatic amines, and the preparation of derivatives of amide compounds.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The supported catalyst provided by the present invention includes a support and an active component. By limiting the Brønsted acid density of the support, especially by controlling the silicon-to-aluminum ratio of the silicon-modified alumina to be less than 1, and by connecting silicon to the surface of the alumina through Si-O-Al chemical bonds and connecting adjacent silicon on the surface of the alumina through Si-O-Si chemical bonds, the complex acidic sites on the surface of the alumina are controlled, resulting in silicon-modified alumina with extremely low Brønsted acid density as the support. Combined with active components of specific dispersion and specific content, the supported catalyst has high catalytic activity and selectivity. In particular, by controlling the content of active components in the catalyst and the content of components in the support, it is more beneficial to improve the activity of the supported catalyst. At the same time, the method provided by the present invention simplifies the process flow and facilitates industrial production.

[0023] (2) The supported catalyst provided by the present invention has high conversion rate and selectivity when used in the catalytic synthesis of lysine-type antibacterial monomers, the aminoalkylation reaction of aromatic amines, and the preparation of derivatives of amide compounds. In particular, it can inhibit side reactions such as alcoholysis and ring opening of amide bonds in the catalytic synthesis of lysine-type antibacterial monomers, which is more conducive to improving the yield of target products. Attached Figure Description

[0024] Figure 1 This is a TEM characterization image of the catalyst Pd / AS-1 prepared in Example 1;

[0025] Figure 2 These are the pyridine infrared characterization spectra of the supports in the catalysts prepared in Example 1 and Comparative Examples 1-2, with a wavenumber of 1540 cm⁻¹. -1 The absorption peak at that location indicates the Brønsted acid site on the support surface;

[0026] Figure 3 (a) is the transmission infrared spectrum of the support in the catalyst prepared in Example 1; Figure 3(b) Transmission infrared spectrum of the support in the catalyst prepared in Comparative Example 1, wherein the wavenumber is 1066 cm⁻¹. -1 and 1160cm -1 The signal peaks at these locations are the vibrational absorption peaks of the Si-O-Si and Si-O-Al bonds, respectively. Detailed Implementation

[0027] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] In this invention, unless otherwise specified, "first," "second," and "third" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish that these are not the same material or step. For example, in "first mix," "second mix," and "third mix," "first," "second," and "third" are used only to indicate that these are not the same mix.

[0029] A first aspect of the present invention provides a supported catalyst, the supported catalyst comprising: a support and an active component supported on the support;

[0030] Wherein, the carrier is silicon-modified alumina with a Brønsted acid density ≤ 2 μmol / g; the dispersion of the active component is ≥ 20%;

[0031] Wherein, based on the total weight of the supported catalyst, the content of the support is 90-99.9 wt%, and the content of the active component is 0.1-10 wt%.

[0032] The inventors of this invention discovered that the surface of alumina contains complex acidic sites, and the different types and intensities of these acidic sites significantly limit the application of alumina in the fine chemical industry. Therefore, by loading silicon onto the surface of alumina and ensuring that the silicon is connected to the alumina surface via Si-O-Al chemical bonds, the acidic sites on the alumina surface can be effectively masked, thereby controlling the Brønsted acid (B acid) density on the alumina surface, resulting in a B acid density of ≤2 μmol / g for silicon-modified alumina. Simultaneously, using silicon-modified alumina with low B acid density as a support, combined with active components of specific dispersion and content, can effectively improve the catalytic activity of the supported catalyst, yielding a high-yield target product.

[0033] In this invention, unless otherwise specified, the density of Brønsted acid refers to... Acid density.

[0034] In this invention, the Brønsted acid density parameter is calculated based on the amount of pyridine desorbed by heating; Brønsted acid density = amount of silicon-modified alumina acid used to test the infrared spectrum of pyridine (in μmol) / mass of silicon-modified alumina (in g).

[0035] In some embodiments of the present invention, preferably, based on the total weight of the supported catalyst, the content of the support is 95-99.5 wt%, and the content of the active component is 0.5-5 wt%. Using these preferred conditions is more conducive to improving the catalytic activity and selectivity of the supported catalyst.

[0036] In some embodiments of the present invention, preferably, the active component is selected from at least one of Pt, Pd, Rh, Ir, Ru, and Ni, and more preferably Pt and / or Pd. Using these preferred conditions is more conducive to improving the conversion rate of the raw materials and the selectivity of the target product, thereby increasing the yield of the target product.

[0037] In some embodiments of the present invention, preferably, the dispersion of the active component is 20-80%. Using these preferred conditions is more conducive to improving the dispersion of the active component.

[0038] In some embodiments of the present invention, preferably, the Brønsted acid density of the silicon-modified alumina is 0-2 μmol / g, for example, 0 μmol / g, 0.1 μmol / g, 0.2 μmol / g, 0.3 μmol / g, 0.5 μmol / g, 0.8 μmol / g, 1 μmol / g, 1.4 μmol / g, 1.5 μmol / g, 2 μmol / g, and any value within the range of any two values, preferably 0-1.4 μmol / g, more preferably 0-0.5 μmol / g.

[0039] In some embodiments of the present invention, preferably, the specific surface area of ​​the silicon-modified alumina is 100-220 m² / g. 2 / g; average pore size is 10-30nm; wear index is 1-20%; crushing strength is 50-150N / cm.

[0040] In some embodiments of the present invention, more preferably, the specific surface area of ​​the carrier is 120-200 m². 2 / g; average pore size is 15-25nm; abrasion index is 1-15%; crushing strength is 70-130N / cm.

[0041] In this invention, unless otherwise specified, the specific surface area parameter is measured using a fully automatic isothermal adsorption instrument; the average pore size parameter is calculated using a fully automatic isothermal adsorption instrument in conjunction with the BJH model; the wear index parameter is measured using a wear index analyzer; and the crushing strength parameter is measured using a particle strength tester.

[0042] In some embodiments of the present invention, preferably, the silicon-modified alumina comprises silicon and alumina, wherein the silicon-to-alumina ratio of the silicon-modified alumina is <1, the silicon is connected to the surface of the alumina by Si-O-Al chemical bonds, and adjacent silicon atoms on the surface of the alumina are connected by Si-O-Si chemical bonds.

[0043] In this invention, unless otherwise specified, the silicon bonded to the surface of the alumina via Si-O-Al chemical bonds refers to the shared O portion between Si and Al in the alumina, thereby forming SiO2. x Silicon, in its present form, is anchored to the surface of the alumina.

[0044] In some embodiments of the present invention, preferably, the content of the alumina is 50-90 wt% based on the total weight of the silicon-modified alumina; with SiO x The silicon content is 10-50 wt%, wherein 1 ≤ x ≤ 2; more preferably, based on the total weight of the silicon-modified alumina, the alumina content is 70-80 wt%; with SiO x The silicon content is calculated to be 20-30 wt%, wherein 1 ≤ x ≤ 2. Using preferred conditions is more conducive to reducing the Brønsted acid density of the modified alumina.

[0045] In this invention, unless otherwise specified, the silicon-modified alumina contains no impurities other than silicon and alumina, that is, the sum of the contents of silicon and alumina in the silicon-modified alumina is 100 wt%.

[0046] In some embodiments of the present invention, preferably, the shape of the silicon-modified alumina is selected from spherical or strip-shaped, wherein the spherical shape includes, but is not limited to, microspheres or small spheres.

[0047] In some embodiments of the present invention, preferably, the alumina is selected from γ-alumina. Using preferred conditions is more conducive to improving the activity of the modified alumina.

[0048] A second aspect of the present invention provides a method for preparing a supported catalyst, the method comprising the following steps:

[0049] (1) The aluminum source, the acidic compound and water are mixed in a first mixture to obtain a first mixture;

[0050] (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain molded alumina;

[0051] (3) Dissolve the shaped alumina in water, first add an alkaline compound to adjust the pH to 7-12, then add a silicon source for a second mixing to obtain a second mixture;

[0052] (4) The second mixture is subjected to solid-liquid separation, and the obtained silicon-modified alumina precursor is subjected to second drying and second calcination in sequence, and the obtained silicon-modified alumina is used as a carrier.

[0053] (5) A soluble metal salt is loaded onto the surface of the support, and the resulting catalyst precursor is subjected to a third drying and a third calcination to obtain a supported catalyst.

[0054] In some embodiments of the present invention, preferably, in step (1), the content of aluminum source in the first mixture is 0.01-10 wt%, preferably 0.05-5 wt%; the content of acidic compound is 0.01-3 wt%, preferably 0.05-1 wt%. In the present invention, the ratio of the amount of aluminum source, acidic compound and water fed / used can satisfy the above-mentioned limitations.

[0055] In this invention, a wide range of aluminum sources can be selected. Preferably, the aluminum source is a soluble aluminum salt, including but not limited to γ-alumina, hydroxyalumina, boehmite, aluminum chloride, aluminum nitrate, etc. When the aluminum source is selected from γ-alumina, steps (1)-(2) are to acidify the surface of the powdered alumina to form a hydrated hydroxyl state, which facilitates the subsequent addition of alkaline compounds and silicon sources for silicon modification.

[0056] In this invention, a wide range of types of acidic compounds can be selected. Preferably, the acidic compound is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. In this invention, the acidic compound exists in the form of an aqueous solution, and preferably the concentration of the acidic compound in the solution is 1-50 wt%.

[0057] In this invention, the first mixing method has a wide range of options, as long as the aluminum source, acidic compound, and water are mixed. Preferably, the conditions for the first mixing include: a temperature of 15-40°C, preferably 20-30°C; a rotation speed of 100-1000 rpm, preferably 300-1000 rpm; and a time of 0.1-5 h, preferably 0.1-2 h.

[0058] In this invention, there is a wide range of options for the molding method. Preferably, in step (2), the molding method includes, but is not limited to, oil-ammonia droplet molding, spray drying molding, and extrusion molding.

[0059] In this invention, the first drying is intended to remove water from the first mixture. Preferably, in step (2), the conditions for the first drying include: a temperature of 80-120°C and a time of 90-110°C; the time is 1-20 hours, preferably 1-12 hours.

[0060] In this invention, the first drying method has a wide range of options, as long as the conditions for the first drying meet the above-mentioned limitations. Preferably, the first drying method includes, but is not limited to, spray drying, forced-air drying, vacuum drying, etc.

[0061] In some embodiments of the present invention, preferably, in step (2), the conditions for the first calcination include: a temperature of 700-1200℃, preferably 800-1000℃; and a time of 1-10h, preferably 1-5h. In the present invention, the first calcination is carried out in a muffle furnace or a tube furnace, and the calcination atmosphere is a non-reducing gas, preferably at least one of air, nitrogen, and argon.

[0062] In this invention, in step (3), the shaped alumina is first dissolved in water, an alkaline compound is added to adjust the pH, and then a silicon source is added for a second mixing, in order to obtain polyhydroxy silicic acid and / or hydroxy hydrated silicon.

[0063] In some embodiments of the present invention, the pH is preferably adjusted to 8-12, for example, 8, 9, 10, 10.5, 11, 11.5, 12, and any value within the range of any two values, preferably 10.5-11.5.

[0064] In some embodiments of the present invention, preferably, the shaped alumina is calculated as Al2O3 and the alumina is calculated as SiO2. x The weight ratio of the silicon source is 5-9:1-5, preferably 7-8:2-3; wherein 1≤x≤2.

[0065] In this invention, a wide range of silicon sources can be selected. Preferably, the silicon source is a soluble silicon salt, preferably selected from organosilicon salts and / or inorganic silicon salts, including but not limited to at least one of tetramethylsilane, tetramethylsilane, silica aerogel, and silicon tetrachloride.

[0066] In this invention, unless otherwise specified, solubility means being easily soluble in water, or being easily soluble in water with the help of additives.

[0067] In some embodiments of the present invention, preferably, the alkaline compound is selected from at least one of ammonium carbonate, ammonium bicarbonate and ammonia water.

[0068] In some embodiments of the present invention, preferably, the conditions for the second mixing include: a temperature of 20-70°C, preferably 25-60°C; a rotation speed of 100-1000 rpm, preferably 300-1000 rpm; and a time of 1-20 h, preferably 6-12 h.

[0069] In this invention, the solid-liquid separation method has a wide range of options, as long as the second mixture is subjected to solid-liquid separation to obtain the modified alumina precursor; the solid-liquid separation method includes, but is not limited to, filtration, sedimentation, etc.

[0070] In this invention, the second drying is intended to remove residual moisture from the silicon-modified alumina precursor. Preferably, in step (4), the conditions for the second drying include: a temperature of 80-120°C and a time of 90-110°C; the time is 1-20 hours, preferably 1-12 hours.

[0071] In this invention, the second drying method has a wide range of options, as long as the conditions for the second drying meet the above-mentioned limitations. Preferably, the second drying method includes, but is not limited to, spray drying, forced-air drying, vacuum drying, etc.

[0072] In some embodiments of the present invention, preferably, in step (4), the conditions for the second calcination include: a temperature of 400-1000℃, preferably 500-900℃; and a time of 1-10h, preferably 1-5h. In the present invention, the second calcination is carried out in a muffle furnace or a tube furnace, and the calcination atmosphere is a non-reducing gas, preferably at least one of air, nitrogen, and argon.

[0073] In some embodiments of the present invention, preferably, in step (5), the loading of the soluble metal salt, based on the metal element, is 0.1-10 wt%, more preferably 0.5-5 wt%.

[0074] In this invention, the loading method has a wide range of options, as long as the loading amount of the soluble metal salt meets the above-mentioned limitations. Preferably, the loading method is selected from impregnation and deposition / precipitation methods.

[0075] In this invention, when the loading method is impregnation, an impregnation solution containing the soluble metal salt needs to be prepared. Depending on the amount of impregnation solution used, the impregnation method is selected from excess impregnation and saturated impregnation. Depending on the method of impregnation, the impregnation method is selected from immersion impregnation and spray impregnation. By adjusting and controlling the concentration and amount of the impregnation solution or the amount of carrier, a catalyst with a specific loading can be obtained, which is easily understood by those skilled in the art.

[0076] In some embodiments of the present invention, when the loading method is impregnation, the solvent in the impregnation solution containing the soluble metal salt includes, but is not limited to, water, ammonia, and hydrochloric acid. The present invention does not limit the concentration of the soluble metal salt in the impregnation solution containing the soluble metal salt.

[0077] In some embodiments of the present invention, when the loading method is a deposition precipitation method, the solvent in the impregnation solution containing the soluble metal salt includes, but is not limited to, water. The present invention does not limit the concentration of the soluble metal salt in the impregnation solution containing the soluble metal salt.

[0078] In some embodiments of the present invention, preferably, in step (5), the soluble metal salt is selected from hydrochloride, sulfate, nitrate, and acetate containing at least one of Pt, Pd, Rh, Ir, Ru, and Ni, and is more preferably selected from nitrate, sulfate, and nitrate containing Pt and / or Pd. In the present invention, the soluble metal salt includes, but is not limited to, Ni(NO3)2, PdCl2, H2PtCl6, Pd(NO3)2, RuCl3, and iridium acetate.

[0079] In some embodiments of the present invention, preferably, the conditions for the third drying include: a temperature of 80-120°C and a time of 90-110°C; the time is 1-20 hours, preferably 1-12 hours.

[0080] In this invention, the third drying method has a wide range of options, as long as the conditions for the third drying meet the above-mentioned limitations. Preferably, the third drying method includes, but is not limited to, spray drying, forced-air drying, vacuum drying, etc.

[0081] In some embodiments of the present invention, preferably, the conditions for the third calcination include: a temperature of 400-800°C and a time of 450-750°C; the time is 1-10 hours, preferably 1-5 hours. In the present invention, the third calcination is carried out in a muffle furnace or a tube furnace, and the calcination atmosphere is a non-reducing gas, preferably at least one of air, nitrogen, and argon.

[0082] The third aspect of this invention provides a supported catalyst provided in the first aspect, or a supported catalyst prepared by the method provided in the second aspect, for use in the catalytic synthesis of lysine-type antibacterial monomers, the aminoalkylation reaction of aromatic amines, and the preparation of derivatives of amide compounds.

[0083] In some embodiments of the present invention, preferably, the supported catalyst is used to catalyze the synthesis of lysine-type antibacterial monomers, which can effectively improve the conversion rate of raw materials and the selectivity of products, thereby improving the yield of the target product.

[0084] According to a particularly preferred embodiment of the present invention, the supported catalyst comprises: a support and an active component supported on the support; the support is silicon-modified alumina, wherein the Brønsted acid density of the silicon-modified alumina is 0-0.5 μmol / g; and the dispersion of the active component is 20-80%.

[0085] The silicon-modified alumina comprises silicon and alumina, wherein the silicon-alumina ratio of the silicon-modified alumina is <1, the silicon is connected to the surface of the alumina by Si-O-Al chemical bonds, and adjacent silicon atoms on the surface of the alumina are connected by Si-O-Si chemical bonds.

[0086] Wherein, based on the total weight of the supported catalyst, the content of the support is 95-99.5 wt%, and the content of the active component is 0.5-5 wt%.

[0087] The supported catalyst is prepared by the following method:

[0088] (1) The aluminum source, the acidic compound and water are mixed in a first mixture to obtain a first mixture;

[0089] (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain molded alumina;

[0090] (3) Dissolve the shaped alumina in water, first add an alkaline compound to adjust the pH to 7-12, then add a silicon source for a second mixing to obtain a second mixture;

[0091] (4) The second mixture is subjected to solid-liquid separation, and the obtained silicon-modified alumina precursor is subjected to second drying and second calcination in sequence, and the obtained silicon-modified alumina is used as a carrier.

[0092] (5) A soluble metal salt is loaded onto the surface of the support, and the resulting catalyst precursor is subjected to a third drying and a third calcination to obtain a supported catalyst.

[0093] The present invention will be described in detail below through embodiments.

[0094] The Brønsted acid density parameter is calculated based on the amount of pyridine desorbed upon heating; that is, Brønsted acid density = amount of pyridine in silicon-modified alumina used to test the infrared spectrum of pyridine (in μmol) / mass of silicon-modified alumina (in g).

[0095] The specific surface area parameter was measured using a fully automatic isothermal adsorption instrument; the average pore size parameter was calculated using a fully automatic isothermal adsorption instrument in conjunction with the BJH model; the wear index parameter was measured using a wear index analyzer; and the crushing strength parameter was measured using a particle strength tester.

[0096] The physical properties of the catalysts prepared in Examples 1-13 and Comparative Examples 1-6 are listed in Table 1.

[0097] Example 1

[0098] (1) 80g of aluminum source (boehmite), 5g of acidic compound (30wt% dilute nitric acid) and 800mL of water were mixed in a 1500mL stirred tank for the first time (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0099] (2) The first mixture was spray-dried (at 100°C for 5 hours) and then calcined in a muffle furnace at 800°C for 3 hours under static air to obtain micro-spherical alumina.

[0100] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 10, then add 60 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 25℃, rotation speed 600 rpm, time 12 h) to obtain the second mixture;

[0101] (4) The above second mixture was subjected to solid-liquid separation. The obtained silicon-modified alumina precursor was dried in a vacuum drying oven at 100°C for 5 hours and then calcined in a muffle furnace at 600°C under static air for 3 hours to obtain microspherical silicon-modified alumina as carrier AS-1.

[0102] (5) Prepare a Pd(NH3)4Cl2 solution with 30wt% ammonia water, and impregnate it onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 10wt% Pd. After drying in a vacuum drying oven at 100℃ for 5h, calcine it in a muffle furnace at 500℃ for 3h under static air to obtain microspherical catalyst Pd / AS-1.

[0103] The TEM image of catalyst Pd / AS-1 is shown below. Figure 1 As shown; by Figure 1 It can be seen that the active component Pd in ​​catalyst Pd / AS-1 is uniformly loaded on the surface of the support;

[0104] The infrared characterization spectrum of pyridine for carrier AS-1 is as follows: Figure 2 As shown, by Figure 2 It can be seen that the carrier AS-1 has extremely low Brønsted acid sites;

[0105] The transmission infrared spectrum of carrier AS-1 is as follows: Figure 3 As shown in (a); by Figure 3 (a) It can be seen that the wave number is 1066 cm⁻¹ -1 and 1160cm -1 The signal peaks at these locations are vibrational absorption peaks of Si-O-Si and Si-O-Al bonds, respectively, indicating that silicon in silicon-modified alumina is bonded to alumina through chemical bonds, and that adjacent silicon on the surface of alumina is bonded to SiO2. x Clusters of (1≤x≤2) exist.

[0106] Example 2

[0107] (1) 50g of aluminum source (boehmite), 10g of acidic compound (5wt% dilute nitric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 20℃, speed 500rpm, time 1h) to obtain the first mixture;

[0108] (2) The first mixture above was spray-dried and shaped (temperature 100℃, time 5h), and then calcined in a muffle furnace at static air 1000℃ for 1h to obtain micro-spherical shaped alumina.

[0109] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonium bicarbonate) to adjust the pH to 9, then add 50 g of silicon source (silica aerogel) for a second mixing (temperature 25℃, rotation speed 500 rpm, time 8 h) to obtain the second mixture;

[0110] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a vacuum drying oven at 100°C for 5 hours and then calcined in a tube furnace at 800°C for 2 hours in a nitrogen atmosphere to obtain microspherical silicon-modified alumina as carrier AS-2.

[0111] (5) Prepare a Ni(NO3)2 solution with deionized water and impregnate it onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 6wt% Ni. After drying in a vacuum drying oven at 100℃ for 5h, it is calcined in a muffle furnace at 500℃ for 3h under static air to obtain microspherical catalyst Ni / AS-2.

[0112] Example 3

[0113] (1) 20g of aluminum source (aluminum hydroxide), 1g of acidic compound (30wt% dilute hydrochloric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 30℃, speed 500rpm, time 1h) to obtain the first mixture;

[0114] (2) The first mixture above is extruded, dried by forced air (temperature 100℃, time 5h), and then calcined in a muffle furnace at static air 800℃ for 3h to obtain strip-shaped alumina.

[0115] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 10, then add 56 g of silicon source (silicon tetrachloride) for a second mixing (temperature 50℃, speed 500 rpm, time 10 h) to obtain the second mixture;

[0116] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a tube furnace at 600°C for 6 hours in a nitrogen atmosphere to obtain strip-shaped silicon-modified alumina as carrier AS-3.

[0117] (5) Prepare H2PtCl6 solution with deionized water and impregnate it onto the surface of the above support by saturation impregnation method to obtain a catalyst precursor with a loading of 2wt%Pt. After drying in a vacuum drying oven at 100℃ for 5h, calcine in a tube furnace at 500℃ for 3h under H2 / N2 atmosphere to obtain strip-shaped catalyst Pt / AS-3.

[0118] Example 4

[0119] (1) 50g of aluminum source (boehmite), 2g of acidic compound (50wt% dilute phosphoric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 800rpm, time 1h) to obtain the first mixture;

[0120] (2) The first mixture above is formed by drop ball molding, dried by forced air (temperature is 100℃, time is 5h), and then calcined in a muffle furnace at static air of 1000℃ for 2h to obtain small spherical alumina.

[0121] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 10, then add 48 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 35℃, rotation speed 500 rpm, time 6 h) to obtain the second mixture;

[0122] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a tube furnace at 800°C for 3 hours in a nitrogen atmosphere to obtain small spherical silicon-modified alumina as carrier AS-4.

[0123] (5) Prepare a Pd(NH3)4(NO3)2 solution with 30wt% ammonia water, and impregnate it onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 2wt% Pd. After drying in a vacuum drying oven at 100℃ for 5h, calcine it in a tube furnace at 500℃ for 3h under H2 / N2 atmosphere to obtain small spherical catalyst Pd / AS-4.

[0124] Example 5

[0125] (1) 80g of aluminum source (γ-alumina), 4g of acidic compound (25wt% dilute sulfuric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0126] (2) The first mixture above is extruded, dried by forced air (temperature 100℃, time 5h), and then calcined in a muffle furnace at static air 800℃ for 3h to obtain strip-shaped alumina.

[0127] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 8, then add 60 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 25℃, rotation speed 600 rpm, time 5 h) to obtain the second mixture;

[0128] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a tube furnace at 600°C for 3 hours in a nitrogen atmosphere to obtain strip-shaped silicon-modified alumina as carrier AS-5.

[0129] (5) Prepare a PdCl2 solution with 36wt% hydrochloric acid and impregnate it onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 10wt% Pd. After drying in a vacuum drying oven at 100℃ for 5h, calcine in a tube furnace at 500℃ for 3h under H2 / N2 atmosphere to obtain strip-shaped catalyst Pd / AS-5.

[0130] Example 6

[0131] (1) 60g of aluminum source (aluminum hydroxide), 5g of acidic compound (10wt% dilute phosphoric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 500rpm, time 1h) to obtain the first mixture;

[0132] (2) The first mixture was spray-dried and shaped (at a temperature of 100°C for 5 hours), and then calcined in a muffle furnace at a static air temperature of 900°C for 3 hours to obtain micro-spherical shaped alumina.

[0133] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 9, then add 28 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 25℃, rotation speed 500 rpm, time 9 h) to obtain the second mixture;

[0134] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a tube furnace at 800°C for 6 hours in a nitrogen atmosphere to obtain microspherical silicon-modified alumina as carrier AS-6.

[0135] (5) Prepare RuCl3 solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain a catalyst precursor with a loading of 0.5wt%Ru. After drying in a vacuum drying oven at 100℃ for 5h, it is calcined in a muffle furnace at static air at 500℃ for 3h to obtain microspherical catalyst Ru / AS-6.

[0136] Example 7

[0137] (1) 80g of aluminum source (γ-alumina), 50g of acidic compound (20wt% dilute nitric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 800rpm, time 1h) to obtain the first mixture;

[0138] (2) The first mixture above was spray-dried and shaped (temperature 100℃, time 5h), and then calcined in a muffle furnace at static air 1000℃ for 1h to obtain micro-spherical shaped alumina.

[0139] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonium bicarbonate) to adjust the pH to 7.5, then add 70 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 40℃, rotation speed 800 rpm, time 8 h) to obtain the second mixture;

[0140] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a tube furnace at 800°C for 6 hours in a nitrogen atmosphere to obtain microspherical silicon-modified alumina as carrier AS-7.

[0141] (5) Prepare an iridium acetate solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain a catalyst precursor with a loading of 0.2wt%Ir. After drying in a vacuum drying oven at 100℃ for 5h, it is calcined in a muffle furnace at 600℃ for 3h under static air to obtain microspherical catalyst Ir / AS-7.

[0142] Example 8

[0143] (1) 80g of aluminum source (aluminum hydroxide), 5g of acidic compound (20wt% dilute sulfuric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0144] (2) The first mixture above is formed by drop ball molding, dried by forced air (temperature is 100℃, time is 5h), and then calcined in a muffle furnace at static air of 900℃ for 2h to obtain small spherical alumina.

[0145] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 10, then add 50 g of silicon source (silica aerogel) for a second mixing (temperature 25℃, speed 600 rpm, time 12 h) to obtain the second mixture;

[0146] (4) The second mixture above is subjected to solid-liquid separation. The resulting silicon-modified alumina precursor is dried in a blower oven at 100°C for 5 hours and then calcined in air at 600°C for 4 hours in a muffle furnace to obtain small spherical silicon-modified alumina as carrier AS-8.

[0147] (5) Prepare RhCl3 solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain a catalyst precursor with a loading of 2wt%Rh. After drying in a vacuum drying oven at 100℃ for 5h, calcine in a muffle furnace at 400℃ under static air for 5h to obtain microspherical catalyst Rh / AS-8.

[0148] Example 9

[0149] (1) 50g of aluminum source (boehmite), 8g of acidic compound (15wt% dilute sulfuric acid) and 800mL of water were mixed in a 1500mL stirred tank for the first time (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0150] (2) The first mixture was spray-dried and shaped (at a temperature of 100°C for 5 hours), and then calcined in a muffle furnace at a static air temperature of 1000°C for 3 hours to obtain micro-spherical shaped alumina.

[0151] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 9, then add 76 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 60℃, rotation speed 600 rpm, time 6 h) to obtain the second mixture;

[0152] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in a muffle furnace at 800°C for 2 hours to obtain microsphere silicon-modified alumina as carrier AS-9.

[0153] (5) Prepare H2PtCl6 solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain catalyst precursor with a loading of 5wt%Pt. After drying in a blower drying oven at 100℃ for 5h, calcine in a tube furnace at 400℃ for 5h in H2 / N2 atmosphere to obtain microspherical catalyst Pt / AS-9.

[0154] Example 10

[0155] (1) 50g of aluminum source (boehmite), 8g of acidic compound (15wt% dilute sulfuric acid) and 800mL of water were mixed in a 1500mL stirred tank for the first time (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0156] (2) The first mixture was spray-dried and shaped (at a temperature of 100°C for 5 hours), and then calcined in a muffle furnace at a static air temperature of 1000°C for 3 hours to obtain micro-spherical shaped alumina.

[0157] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 9, then add 26 g of silicon source (silicon tetrachloride) for a second mixing (temperature 60℃, rotation speed 600 rpm, time 6 h) to obtain the second mixture;

[0158] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in air at 800°C for 2 hours to obtain microsphere silicon-modified alumina as carrier AS-10.

[0159] (5) Prepare H2PtCl6 solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain catalyst precursor with a loading of 5wt%Pt. After drying in a blower drying oven at 100℃ for 5h, calcine in a tube furnace at 400℃ for 5h in H2 / N2 atmosphere to obtain microspherical catalyst Pt / AS-10.

[0160] Example 11

[0161] (1) 40g of aluminum source (γ-alumina), 10g of acidic compound (10wt% dilute hydrochloric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 600rpm, time 1h) to obtain the first mixture;

[0162] (2) The first mixture above is formed by drop ball molding, dried by forced air (temperature is 100℃, time is 5h), and then calcined in a muffle furnace at static air temperature of 800℃ for 3h to obtain small spherical alumina.

[0163] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonia) to adjust the pH to 12, then add 64 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 25℃, rotation speed 600 rpm, time 8 h) to obtain the second mixture;

[0164] (4) The second mixture was subjected to solid-liquid separation. The resulting silicon-modified alumina precursor was dried in a blower oven at 100°C for 5 hours and then calcined in air at 600°C for 6 hours to obtain small spherical silicon-modified alumina as carrier AS-11.

[0165] (5) Prepare a Ni(NO3)2 solution with deionized water and impregnate it onto the surface of the above support by saturation impregnation method to obtain a catalyst precursor with a loading of 1wt% Ni. After drying in a blower drying oven at 100℃ for 5h, calcine in a muffle furnace at 400℃ for 6h under static air to obtain microspherical catalyst Ni / AS-11.

[0166] Example 12

[0167] (1) 60g of aluminum source (boehmite), 10g of acidic compound (15wt% dilute sulfuric acid) and 800mL of water were mixed in a 1500mL stirred tank (temperature 25℃, speed 500rpm, time 1h) to obtain the first mixture;

[0168] (2) The first mixture above is extruded, dried by forced air (temperature 100℃, time 5h), and then calcined in a muffle furnace at static air 900℃ for 5h to obtain strip-shaped alumina.

[0169] (3) Dissolve the above-mentioned shaped alumina in 800 mL of water, first add an alkaline compound (ammonium bicarbonate) to adjust the pH to 7.8, then add 40 g of silicon source (tetraethyl orthosilicate) for a second mixing (temperature 25℃, rotation speed 600 rpm, time 8 h) to obtain the second mixture;

[0170] (4) The second mixture above is subjected to solid-liquid separation. The resulting silicon-modified alumina precursor is dried in a blower oven at 100°C for 5 hours and then calcined in a muffle furnace at 800°C for 3 hours to obtain strip-shaped silicon-modified alumina as carrier AS-12.

[0171] (5) Prepare a Pd(NH3)4(NO3)2 solution with deionized water and impregnate it onto the surface of the above support by deposition precipitation method to obtain a catalyst precursor with a loading of 4wt% Pd. After drying in a blower drying oven at 100℃ for 5h, calcine it in a tube furnace at 500℃ for 3h in H2 / N2 atmosphere to obtain microspherical catalyst Pd / AS-12.

[0172] Example 13

[0173] The method of Example 1 is different except that in step (5), a Pt(NH3)4(NO3)2 solution is prepared with 30wt% ammonia water and impregnated onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 5wt% Pt. The other conditions are the same to obtain microspherical catalyst Pd / AS-13.

[0174] Comparative Example 1

[0175] 800 mL of deionized water, 80 g of boehmite and 10 g of 10 wt% dilute nitric acid aqueous solution were mixed in a 1500 mL stirred tank (temperature 25℃, rotation speed 800 rpm, time 5 h). The resulting mixture was subjected to solid-liquid separation. The solid obtained was spray-dried and then calcined in a muffle furnace under static air at 800℃ for 3 h to obtain microspherical alumina as carrier DS-1.

[0176] A Pd(NH3)4Cl2 solution was prepared by adding 30wt% ammonia water and impregnated onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 1wt% Pd. After drying in a vacuum drying oven at 100℃ for 5h, it was calcined in a muffle furnace at 500℃ under static air for 3h to obtain microspherical catalyst Pd / DS-1.

[0177] The infrared characterization spectrum of the pyridine support in catalyst Pd / DS-1 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the carrier DS-1 has a high number of Brønsted acid sites.

[0178] The transmission infrared spectrum of carrier DS-1 is as follows: Figure 3 As shown in (b); by Figure 3 (b) It can be seen that the wave number is 1066 cm⁻¹. -1 and 1160cm -1 The absence of signal peaks indicates that Si-O-Si and Si-O-Al bonds are absent in the carrier DS-1.

[0179] Comparative Example 2

[0180] 800 mL of deionized water, 80 g of boehmite, and 20 g of 5 wt% dilute nitric acid solution were mixed in a 1500 mL stirred tank (temperature 25℃, speed 800 rpm, time 5 h). Then, 60 g of tetraethyl orthosilicate was added, and ammonia was added to adjust the pH to 12. The mixture was stirred at 25℃ for 12 h. The resulting mixture was spray-dried and calcined in a muffle furnace under static air at 800℃ for 3 h to obtain microspherical silicon-modified alumina as carrier DS-2.

[0181] A Pd(NH3)4Cl2 solution was prepared by adding 30wt% ammonia water and impregnated onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 10wt% Pd. After drying in a vacuum drying oven at 100℃ for 5h, it was calcined in a muffle furnace at static air at 500℃ for 3h to obtain microspherical catalyst Pd / DS-2.

[0182] The infrared characterization spectrum of the pyridine support in the catalyst Pd / DS-2 is shown below. Figure 2As shown, by Figure 2 It can be seen that the carrier DS-2 has a high number of Brønsted acid sites.

[0183] Comparative Example 3

[0184] The method of Example 1 is different except that steps (1)-(2) are omitted. That is, 80g of aluminum source (pseudoboehmite) is directly dissolved in 800mL of water, and the other conditions are the same to obtain microspherical silicon-modified alumina as carrier DS-3.

[0185] Following step (5), with the other conditions remaining the same, microspherical catalyst Pd / DS-3 was obtained.

[0186] Comparative Example 4

[0187] The method of Example 1 is different except that step (2) is omitted. That is, the first mixture obtained in step (1) is directly subjected to step (3) under the same conditions to obtain microspherical silicon-modified alumina as carrier DS-4.

[0188] Following step (5), with the other conditions remaining the same, the microspherical catalyst Pd / DS-4 was obtained.

[0189] Comparative Example 5

[0190] The method of Example 1 is different except that in step (3), the above-mentioned shaped alumina, 800 mL of water, alkaline compound (ammonia) and 60 g of silicon source (tetraethyl orthosilicate) are directly mixed for the second time (temperature is 25°C, rotation speed is 600 rpm, time is 12 h), and the pH is adjusted to 10. The other conditions are the same, and microsphere silicon-modified alumina is obtained as carrier DS-5.

[0191] Following step (5), with the other conditions remaining the same, the microspherical catalyst Pd / DS-5 was obtained.

[0192] Comparative Example 6

[0193] The method of Example 1 is the same, except that in step (3), ammonia is not added to adjust the pH to 10, and the other conditions are the same, so that microspheres of silicon-modified alumina are obtained as carrier DS-6.

[0194] Following step (5), with the other conditions remaining the same, the microspherical catalyst Pd / DS-6 was obtained.

[0195] Table 1

[0196]

[0197]

[0198] Note 1 - Silicon content is expressed as SiO₂ xCalculate, where 1≤x≤2.

[0199] Continued from Table 1

[0200]

[0201]

[0202] As can be seen from the results in Table 1, compared with Comparative Examples 1-6, the supported catalyst prepared by the method provided by this invention, under the premise of satisfying specific structural requirements, namely, the silicon-to-alumina ratio of silicon-modified alumina is <1, silicon is connected to the surface of alumina through Si-O-Al chemical bonds, and adjacent silicon atoms on the surface of alumina are connected through Si-O-Si chemical bonds; it also has lower Brønsted acid density, lower wear index, better crushing strength, better specific surface area, and better average pore size; at the same time, the active component in the catalyst has a higher degree of dispersion, which is more conducive to improving the catalytic activity of the supported catalyst.

[0203] Test case

[0204] The catalytic effects of the supported catalysts prepared in Examples 1-13 and Comparative Examples 1-6 were evaluated.

[0205] Test conditions: In the presence of 50 mL methanol and 0.1 g of the above catalyst, 0.2 g of aminocaprolactam and 0.1 g of paraformaldehyde (weight average molecular weight of 2000 g / mol) were subjected to a hydrogen-induced reaction in a batch high-pressure reactor. The conditions for the hydrogen-induced reaction were: hydrogen pressure of 0.3 MPa, temperature of 80 °C, and time of 3 h. The reaction products were obtained, including dimethylaminocaprolactam, methylaminocaprolactam, and other byproducts.

[0206] The catalytic reaction results were analyzed by gas chromatography, and the test results are listed in Table 2.

[0207] Table 2

[0208]

[0209]

[0210] Note: Conversion rate of 2-aminocaprolactam, %.

[0211] As can be seen from the results in Table 2, compared with Comparative Examples 1-6, using the supported catalysts provided in Examples 1-13 for the hydrogenation reaction of aminocaprolactam can more effectively improve the selectivity of dimethylaminocaprolactam, thereby increasing the yield of dimethylaminocaprolactam.

[0212] Comparing Examples 1-13, it can be seen that when the active component in the catalyst is selected from Pd and Pt, the selectivity of dimethylaminocaprolactam can be improved more effectively for the hydrogenation reaction of aminocaprolactam, thereby increasing the yield of dimethylaminocaprolactam; when the active component in the catalyst is selected from Ni, Ru, Ir, Rh, etc., although a certain yield of dimethylaminocaprolactam can be obtained, the selectivity of dimethylaminocaprolactam is not high.

[0213] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A supported catalyst, characterized in that, The supported catalyst includes a support and an active component supported on the support; The carrier is silicon-modified alumina with a Brønsted acid density ≤ 2 μmol / g; the silicon-modified alumina comprises silicon and alumina, wherein the silicon-to-alumina ratio is < 1, the silicon is bonded to the surface of the alumina via Si-O-Al chemical bonds, and adjacent silicon atoms on the surface of the alumina are bonded via Si-O-Si chemical bonds; based on the total weight of the silicon-modified alumina, the alumina content is 50-90 wt%; and SiO2 is used as the carrier. x The silicon content is calculated to be 10-50 wt%, wherein 1 ≤ x ≤ 2; The dispersion of the active component is 20-80%; Wherein, based on the total weight of the supported catalyst, the content of the support is 90-99.9 wt%, and the content of the active component is 0.1-10 wt%. The supported catalyst is prepared by the following method: (1) The aluminum source, the acidic compound, and water are mixed in a first mixture to obtain a first mixture; (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain shaped alumina; (3) Dissolve the shaped alumina in water, first add an alkaline compound to adjust the pH to 7-12, then add a silicon source for a second mixing to obtain a second mixture; (4) The second mixture is subjected to solid-liquid separation, and the resulting silicon-modified alumina precursor is subjected to a second drying and a second calcination in sequence, and the resulting silicon-modified alumina is used as a carrier. (5) A soluble metal salt is loaded onto the surface of the support, and the resulting catalyst precursor is subjected to a third drying and a third calcination to obtain a supported catalyst.

2. The supported catalyst according to claim 1, wherein, The active component is selected from at least one of Pt, Pd, Rh, Ir, Ru, and Ni; And / or, based on the total weight of the supported catalyst, the content of the support is 95-99.5 wt%, and the content of the active component is 0.5-5 wt%.

3. The supported catalyst according to claim 2, wherein, The active component is selected from Pt and / or Pd.

4. The supported catalyst according to any one of claims 1-3, wherein, The density of the Brønsted acid in the silicon-modified alumina is 0-2 μmol / g; And / or, the specific surface area of ​​the silicon-modified alumina is 100-220 m² / g. 2 / g; average pore size is 10-30nm; wear index is 1-20%; crushing strength is 50-150N / cm.

5. The supported catalyst according to claim 4, wherein, The Brønsted acid density of the silicon-modified alumina is 0-1.4 μmol / g; The specific surface area of ​​the silicon-modified alumina is 120-200 m². 2 / g; average pore size is 15-25nm; wear index is 1-15%; crushing strength is 70-130N / cm.

6. The supported catalyst according to claim 5, wherein, The Brønsted acid density of the silicon-modified alumina is 0-0.5 μmol / g.

7. The supported catalyst according to any one of claims 1-3, 5 and 6, wherein, Based on the total weight of the silicon-modified alumina, the alumina content is 70-80 wt%; with SiO2 as the main component. x The silicon content is calculated to be 20-30 wt%, wherein 1 ≤ x ≤ 2.

8. A method for preparing a supported catalyst according to any one of claims 1-7, characterized in that, The method includes the following steps: (1) The aluminum source, the acidic compound, and water are mixed in a first mixture to obtain a first mixture; (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain shaped alumina; (3) Dissolve the shaped alumina in water, first add an alkaline compound to adjust the pH to 7-12, then add a silicon source for a second mixing to obtain a second mixture; (4) The second mixture is subjected to solid-liquid separation, and the resulting silicon-modified alumina precursor is subjected to a second drying and a second calcination in sequence, and the resulting silicon-modified alumina is used as a carrier. (5) A soluble metal salt is loaded onto the surface of the support, and the resulting catalyst precursor is subjected to a third drying and a third calcination to obtain a supported catalyst.

9. The method according to claim 8, wherein, In step (1), the content of aluminum source in the first mixture is 0.01-10 wt%; the content of acidic compound is 0.01-3 wt%. And / or, in step (2), the molding method is selected from oil-ammonia droplet molding, spray drying molding, and extrusion molding; And / or, in step (2), the conditions for the first calcination include: a temperature of 700-1200℃ and a time of 1-10h.

10. The method according to claim 9, wherein, In step (1), the content of aluminum source in the first mixture is 0.05-5 wt%; the content of acidic compound is 0.05-1 wt%. In step (2), the conditions for the first roasting include: a temperature of 800-1000℃ and a time of 1-5h.

11. The method according to claims 8-10, wherein, In step (3), the shaped alumina, calculated as Al2O3, and the SiO2... x The weight ratio of the silicon source is 5-9:1-5, where 1≤x≤2; And / or, in step (3), adjust the pH to 8-12.

12. The method according to claim 11, wherein, In step (3), the shaped alumina, calculated as Al2O3, and the SiO2... x The weight ratio of the silicon source is calculated to be 7-8:2-3, where 1≤x≤2; And / or, in step (3), adjust the pH to 10.5-11.

5.

13. The method according to any one of claims 8-10 and 12, wherein, In step (5), the loading of the soluble metal salt, calculated as a metal element, is 0.1-10 wt%; And / or, the loading method is selected from impregnation method and deposition precipitation method.

14. The method according to claim 13, wherein, In step (5), the loading of the soluble metal salt, calculated as metal element, is 0.5-5 wt%.

15. The method according to any one of claims 8-10, 12 and 14, wherein, In step (5), the soluble metal salt is selected from hydrochloride, sulfate, nitrate, and acetate containing at least one of Pt, Pd, Rh, Ir, Ru, and Ni; And / or, the conditions for the third drying include: a temperature of 80-120°C; and a time of 1-20 hours; And / or, the conditions for the third calcination include: a temperature of 400-800℃; and a time of 1-10h.

16. The method according to claim 15, wherein, The conditions for the third drying process include: a temperature of 90-110℃ and a time of 1-12 hours. The conditions for the third roasting include: a temperature of 450-750℃ and a time of 1-5 hours.

17. The use of the supported catalyst according to any one of claims 1-7 in the catalytic reaction of aminocaprolactam to dimethylaminocaprolactam, or the use of the supported catalyst prepared by the method according to any one of claims 8-16 in the catalytic reaction of aminocaprolactam to dimethylaminocaprolactam.

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