Silicon-aluminum-based metal catalyst, preparation method and application thereof, and method for preparing dimethylaminocaprolactam

Abstract

The invention relates to the technical field of catalysts, in particular to a silicon-aluminum-based metal catalyst as well as a preparation method and application thereof, and a method for preparing dimethylaminocaprolactam. The modified aluminum oxide provided by the invention effectively reduces the density of B acid on the premise of ensuring certain density of L acid, and also has low wear index, high crushing strength, high specific surface area and low average pore size; meanwhile, the silicon-aluminum-based metal catalyst containing the modified aluminum oxide has relatively high catalytic activity, and has relatively high raw material conversion rate and target product selectivity when being particularly used for preparing dimethylaminocaprolactam.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a silicon-aluminum-based metal catalyst and its application, and a method for preparing dimethylaminocaprolactam. Background Art

[0002] Catalyst supports are essential building blocks for the synthesis of supported catalysts. Their structure and physicochemical properties significantly influence the properties and applications of supported catalysts. Alumina is an important and common industrial catalyst support, and its properties, such as reactivity, hydrothermal stability, and wear resistance, are key indicators for evaluating catalyst supports. Surface modification of alumina can enhance certain properties, which is of great significance for expanding its application range.

[0003] CN101448565A discloses an alumina with high hydrothermal stability. The hydrothermal stability of the transition alumina used as an adsorbent and catalyst support is improved by treating the transition alumina with a soluble silicon inorganic compound.

[0004] CN107774248A discloses a silicon-modified Fischer-Tropsch synthesis catalyst and its application. The alumina catalyst carrier synthesized by the silicon modification method has excellent stability and wear resistance in the Fischer-Tropsch reaction.

[0005] CN106582597A discloses a silicon-modified alumina and its preparation method and application. By adjusting the pH value of the mixed system of aluminum sol and silica sol, it is possible to flexibly switch between focusing on improving pore volume and focusing on improving B acid content. The material surface B / L is 40-95%, and the pore volume is 0.8-1.2cm 3 / g.

[0006] CN113562751A discloses a modified pseudo-boehmite and a preparation method thereof. During the preparation of the modified pseudo-boehmite, by adding a phosphorus-containing compound, a non-metallic auxiliary compound, and a grain growth regulator, and by staged control of the pH value during the preparation process, the modified pseudo-boehmite has a specific surface hydroxyl distribution after calcination, thereby imparting to the catalyst excellent heavy oil hydrogenation activity and high stability.

[0007] None of the above existing technologies involve how to regulate the complex acid sites on the surface of alumina; usually, the different types and strengths of acid sites greatly limit the application of alumina in the field of fine chemicals. Summary of the Invention

[0008] The present invention aims to overcome the problems of existing modified alumina, such as the complex acid sites, the inability to combine wear resistance, high stability, and controllable acidity, as well as the low activity and short lifespan in the fine chemical industry. The present invention provides a silicon-aluminum-based metal catalyst, its preparation method, and its application, as well as a method for preparing dimethylaminocaprolactam. The modified alumina effectively reduces the B acid density while maintaining a certain L acid density. It also exhibits a low wear index, high crushing strength, high specific surface area, and low average pore size, resulting in a silicon-aluminum-based metal catalyst containing the modified alumina having high catalytic activity.

[0009] To achieve the above objectives, the present invention provides, in a first aspect, a silicon-aluminum-based metal catalyst, comprising: a carrier and an active component supported on the carrier, wherein the carrier is selected from a modified alumina having a B acid density of 0-2 μmol / g and an L acid density of ≥30 μmol / g, wherein the silicon-aluminum ratio of the modified alumina is less than 1, and silicon in the modified alumina is connected to the surface of the alumina via Si-O-Al chemical bonds, and adjacent silicon on the surface of the alumina is connected via Si-O-Si chemical bonds;

[0010] The modified alumina is prepared by the following method: (1) an aluminum source, an acidic compound, a regulator and water are first mixed to obtain a first mixture; (2) the first mixture is sequentially molded, first dried and first calcined to obtain a molded alumina; (3-i) a first silicon source, a cluster regulator and a first solvent are second mixed so that the silicon source and the cluster regulator are in a metastable state in the first solvent, and the obtained metastable mixture is used to wash the molded alumina to obtain a modified alumina precursor; or, (3-ii) the molded alumina is dissolved in water, an alkaline compound is added to adjust the pH to 8-12, and then a mixture containing a second silicon source, a dispersant and a second solvent is added for ultrasonic mixing to obtain a second mixture for solid-liquid separation to obtain a modified alumina precursor; (4) the modified alumina precursor is sequentially second dried and second calcined to obtain the modified alumina.

[0011] A second aspect of the present invention provides a method for preparing a silicon-aluminum-based metal catalyst, characterized in that the preparation method comprises the following steps:

[0012] (1) performing a first mixing of an aluminum source, an acidic compound, a regulating agent, and water to obtain a first mixture;

[0013] (2) subjecting the first mixture to molding, first drying, and first calcination in sequence to obtain molded alumina;

[0014] (3-i) performing a second mixing of a first silicon source, a cluster modifier, and a first solvent, so that the silicon source and the cluster modifier are in a metastable state in the first solvent, and eluting the formed alumina with the obtained metastable mixture to obtain a modified alumina precursor; or

[0015] (3-ii) dissolving the formed alumina in water, adding an alkaline compound to adjust the pH to 8-12, and then adding a mixture containing a second silicon source, a dispersant, and a second solvent, performing ultrasonic mixing to obtain a second mixture, performing solid-liquid separation, and obtaining a modified alumina precursor;

[0016] (4) subjecting the modified alumina precursor to a second drying and a second calcination in sequence, and using the obtained modified alumina as a carrier;

[0017] (5) A soluble metal salt is loaded on the surface of the carrier, and the obtained catalyst precursor is sequentially subjected to a third drying and a third calcination to obtain a silicon-aluminum-based metal catalyst.

[0018] The third aspect of the present invention provides a silicon-aluminum-based metal catalyst provided in the first aspect, or the use of the silicon-aluminum-based metal catalyst prepared by the preparation method provided in the second aspect in catalyzing the synthesis of lysine-type antibacterial monomers, aminoalkylation reactions of aromatic amines, and preparation of derivatives of amide compounds.

[0019] A fourth aspect of the present invention provides a method for preparing dimethylaminocaprolactam, comprising: contacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of a catalyst and a solvent and performing a hydrogenation reaction to obtain dimethylaminocaprolactam;

[0020] Wherein, the catalyst is selected from the silicon-aluminum-based metal catalyst provided in the first aspect, or the silicon-aluminum-based metal catalyst prepared by the preparation method provided in the second aspect.

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

[0022] (1) The modified alumina provided by the present invention regulates the complex acid sites on the surface of the alumina by limiting the silicon in the modified alumina to be connected to the surface of the alumina through Si-O-Al chemical bonds, and the adjacent silicon on the surface of the alumina is connected through Si-O-Si chemical bonds, and combined with a silicon-aluminum ratio of less than 1, thereby effectively reducing the Br acid density of the modified alumina while ensuring that the modified alumina has a low wear index, high crushing strength, high specific surface area and high average pore size. In particular, by regulating the content of silicon, aluminum oxide and impurities in the modified alumina, it is more conducive to regulating the Br acid density of the modified alumina while ensuring a certain L acid density, thereby improving the catalytic activity of the silicon-aluminum-based metal catalyst containing the modified alumina;

[0023] (2) The preparation method of the modified alumina provided by the present invention simplifies the process flow and is convenient for industrial production; in particular, by regulating the amount of the first silicon source input and the size of the cluster particles in the second mixing, or the amount of the second silicon source input and the size of the cluster particles in the ultrasonic mixing, the dispersion of silicon on the surface of the modified alumina is controlled, thereby achieving the regulation of the B acid density and the L acid density of the modified alumina;

[0024] (3) The modified alumina provided by the present invention has a low acid concentration and can be widely used in fine chemicals, especially in catalyst supports, gas-liquid adsorption or solid-phase fillers;

[0025] (4) The modified alumina provided by the present invention is used as a catalyst carrier, and the obtained silicon-aluminum-based metal catalyst has high catalytic activity, especially for catalyzing the synthesis of lysine-type antibacterial monomers, aminoalkylation reactions of aromatic amines, and preparation of derivatives of amide compounds, with high raw material conversion rate and target product selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) is the transmission infrared spectrum of the modified alumina S1 obtained in Example 1, Figure 1 (b) Transmission infrared spectrum of modified alumina DS1 obtained in Comparative Example 1, wherein the wave number is 1066 cm -1 and 1160cm -1 The signal peaks at are the vibration absorption peaks of Si-O-Si and Si-O-Al bonds respectively;

[0027] Figure 2 The pyridine infrared characterization spectra of the modified alumina S1 obtained in Example 1 and the modified alumina DS1-DS2 obtained in Comparative Examples 1-2 are shown, wherein the wave number is 1540 cm -1 The absorption peak at 1450 cm-1 indicates the B acid site on the surface of modified alumina. -1 The absorption peak at indicates the L acid site on the surface of modified alumina;

[0028] Figure 3 1 and 2 are XRD patterns of modified alumina S1 prepared in Example 1 and modified alumina DS2 prepared in Comparative Example 2. DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values 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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0030] In the present invention, unless otherwise specified, the terms "first," "second," and "third" do not indicate a sequential order or limit the materials or steps involved. They are used only to distinguish between different materials or steps. For example, in "first calcination," "second calcination," and "third calcination," the terms "first," "second," and "third" are used only to indicate that these are different calcinations.

[0031] A first aspect of the present invention provides a silicon-aluminum-based metal catalyst, comprising: a carrier and an active component supported on the carrier, wherein the carrier is selected from a modified alumina having a B acid density of 0-2 μmol / g and an L acid density of ≥30 μmol / g, wherein the silicon-aluminum ratio of the modified alumina is less than 1, and silicon in the modified alumina is connected to the surface of the alumina via Si-O-Al chemical bonds, and adjacent silicon on the surface of the alumina is connected via Si-O-Si chemical bonds;

[0032] The modified alumina is prepared by the following method: (1) an aluminum source, an acidic compound, a regulator and water are first mixed to obtain a first mixture; (2) the first mixture is sequentially molded, first dried and first calcined to obtain a molded alumina; (3-i) a first silicon source, a cluster regulator and a first solvent are second mixed so that the silicon source and the cluster regulator are in a metastable state in the first solvent, and the obtained metastable mixture is used to wash the molded alumina to obtain a modified alumina precursor; or, (3-ii) the molded alumina is dissolved in water, an alkaline compound is added to adjust the pH to 8-12, and then a mixture containing a second silicon source, a dispersant and a second solvent is added for ultrasonic mixing to obtain a second mixture for solid-liquid separation to obtain a modified alumina precursor; (4) the modified alumina precursor is sequentially second dried and second calcined to obtain the modified alumina.

[0033] The inventors of the present invention have discovered that the surface of alumina has complex acidic sites, and the different types and strengths of acidic sites have greatly limited the application of alumina in the field of fine chemicals. Therefore, silicon is loaded on the surface of alumina, and the silicon is limited to be connected to the surface of alumina through Si-O-Al chemical bonds, and adjacent silicon on the surface of the alumina is limited to be connected through Si-O-Si chemical bonds. Under the premise of ensuring that the modified alumina has a low wear index, high crushing strength, high specific surface area and low average pore size, the acidic sites on the surface of alumina can be effectively masked, and the Br acid density on the surface of the modified alumina can be regulated to achieve a Br acid density of 0-2 μmol / g and a L acid density of ≥30 μmol / g.

[0034] In the present invention, unless otherwise specified, the silicon in the modified alumina is connected to the surface of the alumina through a Si-O-Al chemical bond, which means that Si and Al in the alumina share some O, thereby making SiO x The silicon in the form of silicon is anchored on the surface of the aluminum oxide.

[0035] In the present invention, unless otherwise specified, the B acid density refers to Acid density, L acid density refers to Lewis acid density.

[0036] In the present invention, the B acid density and L acid density parameters are calculated based on the amount of pyridine desorbed by temperature increase; B acid density = the B acid amount of modified alumina tested by pyridine infrared spectrum (in μmol) / the mass of modified alumina (in g); L acid density = the L acid amount of modified alumina tested by pyridine infrared spectrum (in μmol) / the mass of modified alumina (in g).

[0037] In some embodiments of the present invention, preferably, the B acid density of the 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 in the range consisting of any two values, preferably 0-1.4 μmol / g, more preferably 0-0.5 μmol / g.

[0038] In some embodiments of the present invention, the L acid density of the modified alumina is ≥30 μmol / g, preferably 30-500 μmol / g, for example, 30 μmol / g, 50 μmol / g, 80 μmol / g, 100 μmol / g, 120 μmol / g, 150 μmol / g, 180 μmol / g, 200 μmol / g, 250 μmol / g, 280 μmol / g, 300 μmol / g, 320 μmol / g, 350 μmol / g, 400 μmol / g, 450 μmol / g, 500 μmol / g, and any value in the range consisting of any two values, preferably 100-300 μmol / g, more preferably 120-250 μmol / g.

[0039] In some embodiments of the present invention, preferably, the specific surface area of the modified alumina is 180-320 m 2 / g, preferably 200-300m 2 / g, more preferably 220-280m 2 / g; average pore size is 30-150nm, preferably 50-120nm, more preferably 70-120nm; wear index is 0.1-20%, preferably 0.1-10%, more preferably 0.1-6%; crushing strength is 50-300N / cm, preferably 100-300N / cm, more preferably 150-280N / cm.

[0040] In the present invention, unless otherwise specified, the specific surface area parameters are measured using a fully automatic isothermal adsorption instrument; the average pore size parameters are obtained by using a fully automatic isothermal adsorption instrument in combination with the BJH model; the wear index parameters are measured using a wear index analyzer; and the crushing strength parameters are measured using a particle strength tester.

[0041] In some embodiments of the present invention, preferably, based on the total weight of the modified alumina, SiO x The silicon content is 10-50wt%, preferably 20-30wt%, wherein 1≤x≤2; the aluminum oxide content is 50-90wt%, preferably 70-80wt%. The preferred conditions are more conducive to reducing the B acid density of the modified aluminum oxide and ensuring a certain L acid density.

[0042] In some embodiments of the present invention, it is further preferred that the impurity content, calculated as an element, based on the total weight of the modified alumina is 0-1000 ppm, preferably 0-100 ppm, and the impurities are selected from alkali metals and / or alkaline earth metals. In the present invention, unless otherwise specified, the alkali metals and / or alkaline earth metals are selected from metal elements in Group IA and / or Group IIA.

[0043] In the present invention, the use of a silicon-aluminum-based metal catalyst having an impurity content within the above-defined range is more conducive to improving the selectivity of the target product.

[0044] In the present invention, unless otherwise specified, the modified alumina consists of alumina, silicon and impurities, that is, the total content of alumina, silicon and impurities in the modified alumina is 100 wt%.

[0045] In the present invention, when the modified alumina preparation method adopts step (3-i), the impurities in the modified alumina are mainly derived from the aluminum source that does not participate in the modification; when the modified alumina preparation method adopts step (3-ii), the impurities in the modified alumina are mainly derived from the dispersant and the aluminum source that does not participate in the modification. Therefore, the impurity content in the modified alumina prepared by step (3-ii) is generally higher than the impurity content in the modified alumina prepared by step (3-i).

[0046] In some embodiments of the present invention, preferably, the aluminum oxide in the modified aluminum oxide is γ-alumina, or a mixed crystal phase of γ-alumina and θ-alumina. Adopting the preferred conditions is more conducive to improving the activity of the modified aluminum oxide.

[0047] In some embodiments of the present invention, preferably, the shape of the modified alumina is selected from spheres and strips, wherein the spheres include but are not limited to microspheres and small balls.

[0048] 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, preferably Pt and / or Pd.

[0049] In some embodiments of the present invention, preferably, the dispersion degree of the active ingredient is ≥20%, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and any value in the range of any two values, preferably 20-80%.

[0050] In some embodiments of the present invention, preferably, based on the total weight of the silicon-aluminum-based metal catalyst, the content of the active component is 0.1-10 wt%, preferably 0.5-5 wt%; the content of the carrier is 90-99.9 wt%, preferably 95-99.5 wt%.

[0051] A second aspect of the present invention provides a method for preparing a silicon-aluminum-based metal catalyst, the preparation method comprising the following steps:

[0052] (1) performing a first mixing of an aluminum source, an acidic compound, a regulating agent, and water to obtain a first mixture;

[0053] (2) subjecting the first mixture to molding, first drying, and first calcination in sequence to obtain molded alumina;

[0054] (3-i) performing a second mixing of a first silicon source, a cluster modifier, and a first solvent, so that the silicon source and the cluster modifier are in a metastable state in the first solvent, and eluting the formed alumina with the obtained metastable mixture to obtain a modified alumina precursor; or

[0055] (3-ii) dissolving the formed alumina in water, adding an alkaline compound to adjust the pH to 8-12, and then adding a mixture containing a second silicon source, a dispersant, and a second solvent, performing ultrasonic mixing to obtain a second mixture, performing solid-liquid separation, and obtaining a modified alumina precursor;

[0056] (4) subjecting the modified alumina precursor to a second drying and a second calcination in sequence, and using the obtained modified alumina as a carrier;

[0057] (5) A soluble metal salt is loaded on the surface of the carrier, and the obtained catalyst precursor is sequentially subjected to a third drying and a third calcination to obtain a silicon-aluminum-based metal catalyst.

[0058] In some embodiments of the present invention, preferably, in step (1), the first mixture comprises an aluminum source in an amount of 0.01-10 wt%, preferably 0.05-5 wt%, an acidic compound in an amount of 0.01-3 wt%, preferably 0.05-1 wt%, and a control agent in an amount of 0.01-2 wt%, preferably 0.05-1 wt%. In the present invention, the amount / dosage ratio of the aluminum source, the acidic compound, and the control agent may satisfy the above-mentioned requirements.

[0059] In the present invention, the first mixture consists of an aluminum source, an acidic compound, a regulator and water, that is, the sum of the contents of the aluminum source, the acidic compound, the regulator and water in the first mixture is 100 wt %.

[0060] In the present invention, there is a wide range of choices for the type of aluminum source. Preferably, the aluminum source is a soluble aluminum salt, including but not limited to aluminum oxyhydroxide, pseudo-boehmite, aluminum chloride, aluminum nitrate, dry rubber powder, etc.

[0061] In the present invention, the type of the regulator has a wide range of choices. Preferably, the regulator is a carbon quantum dot, and the diameter of the carbon quantum dot is 1-1.5nm, and the carboxyl density is 2-500μmol / m 2 , preferably 20-200 μmol / m 2 .

[0062] In the present invention, a nanostructured ... 2 , preferably 20-200 μmol / m 2 The carbon quantum dots are used as regulating agents, with the purpose of bonding the carbon quantum dots containing carboxyl groups with aluminum hydroxyl groups during the slurrying process of the aluminum source; at the same time, in step (2), when the aluminum source is first calcined, the carbon quantum dots burn and release CO2 in an orderly manner, forming an ideal and orderly pore structure, and ensuring that the subsequent finished catalyst has a low wear index and high crushing strength.

[0063] In the present invention, the type of the acidic compound has a wide range of selection. Preferably, the acidic compound is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid. In the present invention, the acidic compound is present in the form of an aqueous solution, and preferably the concentration of the acidic compound in the acidic compound solution is 1-50wt%.

[0064] In the present invention, the first mixing method has a wide range of options, as long as the aluminum source, acidic compound, control agent, and water are mixed. Preferably, the first mixing conditions 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 hours, preferably 0.1-2 hours.

[0065] In the present invention, there is a wide range of choices for the molding method. Preferably, in step (2), the molding method includes but is not limited to oil-ammonia drop molding, spray drying molding, and extrusion molding.

[0066] In the present invention, the first drying is to remove water from the first mixture. Preferably, in step (2), the first drying conditions include: a temperature of 80-120°C, a time of 90-110°C, and a time of 1-20 hours, preferably 1-12 hours.

[0067] In the present invention, the first drying method has a wide range of options, as long as the first drying conditions meet the above-mentioned limitations. Preferably, the first drying method includes but is not limited to spray drying, blast drying, vacuum drying, etc.

[0068] In some embodiments of the present invention, preferably, in step (2), the conditions for the first calcination include: a temperature of 700-1500°C, preferably 800-1200°C; and a time of 1-10 hours, preferably 1-5 hours. In the present invention, the first calcination is performed 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.

[0069] In the present invention, in step (3-i), the second mixing is intended to uniformly mix the first silicon source, the cluster control agent and the first solvent. Preferably, the conditions of the second mixing include: a temperature of -10 to 5°C, preferably -8 to 2°C; a speed of 800-2000rpm, preferably 1000-1500rpm; a time of 0.5-5h, preferably 1-4h. In the present invention, a specific second mixing condition is adopted to achieve a metastable state of the dispersed phase (i.e., silicon source and cluster control agent) in the second mixture by high-speed stirring, so that the cluster particles formed by the first silicon source and the cluster control agent in the second mixture have a specific particle size, i.e., the particle size of the cluster particles is 1-50nm, preferably 5-3nm.

[0070] In some embodiments of the present invention, preferably, in the metastable mixture, the particle size of the cluster particles is 1-50 nm, preferably 5-30 nm. In the present invention, the particle size parameters of the cluster particles are measured using a dynamic light scattering particle size analyzer.

[0071] In some embodiments of the present invention, preferably, the mass ratio of the first silicon source, the cluster modifier and the first solvent is 0.1-20:0.1-5:75-99.8, preferably 0.5-15:0.3-2:85-92.

[0072] In the present invention, the first silicon source has a wide range of choices. Preferably, the first silicon source is a soluble silicon salt, preferably selected from organic silicon salts, including but not limited to at least one of ethyl orthosilicate, tetramethylsilane, triethoxysilane, and trimethylsilanol.

[0073] In the present invention, the cluster modulator is defined as a terpene alcohol and / or terpene aldehyde (ketone) compound having a moderate solubility in the first solvent. Preferably, the cluster modulator is selected from at least one of terpene alcohol compounds, terpene aldehyde compounds, and terpene ketone compounds, and is preferably selected from at least one of citronellol, geraniol, nerol, citral, citronellal, and tagetone.

[0074] In the present invention, the first solvent is selected from a compound that modulates the polarity of the first silicon source and the cluster modulator. Preferably, the first solvent is selected from at least one of water, methanol, N,N-dimethylformamide, and N,N-dimethylsulfoxide. In the present invention, the significant difference in polarity between the first solvent and the first silicon source allows the cluster modulator to form microclusters of the first silicon source, facilitating the subsequent formation of Si cluster species with Si-O-Si linkages on the alumina surface.

[0075] In some embodiments of the present invention, preferably, the shaped alumina calculated as Al2O3 and the shaped alumina calculated as SiO x The mass ratio of the metastable mixture is 5-9:1-5, preferably 7-8:2-3; wherein 1≤x≤2.

[0076] In some embodiments of the present invention, the elution conditions include: a flow rate of 0.1-10 mL / min, preferably 0.3-3 mL / min; and an instrument pump pressure of 0.1-2.5 MPa, preferably 0.3-1.2 MPa.

[0077] In the present invention, the elution process includes: eluting the formed alumina with the metastable mixture at a flow rate of 0.1-10 mL / min and a pressure of 0.1-2.5 MPa, collecting the eluted modified alumina precursor on the sieve plate, and collecting the rinsed eluent under the sieve plate.

[0078] In the present invention, in step (3-ii), the shaped alumina is first dissolved in water, an alkaline compound is added to adjust the pH, and then a mixture containing a silicon source is added and ultrasonically mixed to obtain polyhydroxy silicic acid and / or hydroxy hydrated silicon.

[0079] 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 in a range consisting of any two values, preferably 10.5-11.5.

[0080] 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.

[0081] In some embodiments of the present invention, preferably, the mass ratio of the second silicon source, the dispersant and the second solvent is 0.1-20:0.1-5:75-99.8, preferably 0.5-15:0.2-3:80-95.

[0082] In the present invention, the second silicon source has a wide range of options. Preferably, the second silicon source is a soluble silicon salt, preferably selected from organic silicon salts and / or inorganic silicon salts, including but not limited to at least one of ethyl orthosilicate, tetramethylsilicon, silica aerogel, and silicon tetrachloride.

[0083] In the present invention, the dispersant is defined as a C4-C 10 The fatty acid salt compound is preferably at least one of sodium caproate, potassium caprylate, and lithium caprate.

[0084] In the present invention, the second solvent is selected from a compound that modulates the polarity of the second silicon source and the dispersant. Preferably, the second solvent is at least one of water, methanol, N,N-dimethylformamide, and N,N-dimethylsulfoxide. In the present invention, the polarity of the second solvent and the second silicon source differ significantly. This significant difference in polarity allows the second silicon source to form small clusters under the action of the dispersant, subsequently facilitating the formation of Si cluster species with Si-O-Si linkages on the alumina surface.

[0085] In some embodiments of the present invention, preferably, in the mixed material, the particle size of the cluster particles is 1-50 nm, preferably 5-30 nm.

[0086] In some embodiments of the present invention, preferably, the shaped alumina calculated as Al2O3 and the shaped alumina calculated as SiO x The mass ratio of the mixed materials is 5-9:1:5, preferably 7-8:2-3; wherein 1≤x≤2.

[0087] In some embodiments of the present invention, preferably, in step (3-ii), the conditions for ultrasonic mixing include: temperature of 20-70°C, preferably 25-60°C; ultrasonic power of 20-200W, preferably 50-100W; time of 1-30min, preferably 10-20min.

[0088] In the present 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 a modified alumina precursor; the solid-liquid separation method includes but is not limited to filtration, sedimentation, etc.

[0089] In the present invention, preferably, in step (4), the second drying conditions include: temperature of 80-120° C., time of 90-110° C., and time of 1-20 h, preferably 1-12 h.

[0090] In the present invention, the second drying method has a wide range of options. Preferably, the second drying method is selected from microwave drying, and the microwave drying conditions include: power of 800-2000W, preferably 1000-1500W; time of 2-60min, preferably 5-30min;

[0091] In some embodiments of the present invention, preferably, the second calcination is performed at a temperature of 400-1000°C, preferably 500-900°C, and for a time of 1-10 hours, preferably 1-5 hours. In the present invention, the second calcination is performed in a muffle furnace or a tube furnace in a non-reducing atmosphere, preferably at least one of air, nitrogen, and argon.

[0092] In some embodiments of the present invention, the loading amount of the soluble metal salt, calculated as the metal element, is preferably 0.1-10 wt%, for example, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 5 wt%, 10 wt%, and any value in a range consisting of any two values, preferably 0.5-5 wt%. In the present invention, the loading amount is based on the total weight of the silicon-aluminum-based metal catalyst.

[0093] In some embodiments of the present invention, preferably, the soluble metal salt is selected from hydrochlorides, sulfates, nitrates, acetates containing at least one of Pt, Pd, Rh, Ir, Ru and Ni; including but not limited to Ni(NO3)2, PdCl2, H2PtCl6, Pd(NO3)2, RuCl3, iridium acetate.

[0094] In the present 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 the group consisting of impregnation and sedimentation.

[0095] In the present invention, when the loading method is impregnation, an impregnation solution containing the soluble metal salt is prepared. Depending on the amount of impregnation solution used, the impregnation method is selected from excess impregnation and saturation impregnation. Depending on the impregnation method, the impregnation method is selected from immersion impregnation and spray impregnation. A catalyst with a specific loading level can be obtained by adjusting and controlling the concentration and amount of the impregnation solution or the amount of the carrier, as will be readily understood by those skilled in the art.

[0096] 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.

[0097] 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.

[0098] In some embodiments of the present invention, preferably, the conditions for the third drying include: temperature of 80-120° C., time of 90-110° C., and time of 1-20 h, preferably 1-12 h.

[0099] In the present invention, the third drying method has a wide range of options, as long as the third drying conditions meet the above-mentioned limitations. Preferably, the third drying method includes but is not limited to spray drying, blast drying, vacuum drying, etc.

[0100] In some embodiments of the present invention, preferably, the conditions for the third calcination include: a temperature of 400-800°C, a time of 450-750°C, and a time of 1-10 hours, preferably 1-5 hours. In the present invention, the third calcination is performed in a muffle furnace or a tube furnace, and the calcination atmosphere includes but is not limited to air, nitrogen, H2 / N2 atmosphere, etc.

[0101] The third aspect of the present invention provides a silicon-aluminum-based metal catalyst provided in the first aspect, or a silicon-aluminum-based metal catalyst prepared by the preparation method provided in the second aspect, and its use in catalyzing the synthesis of lysine-type antibacterial monomers, aminoalkylation reactions of aromatic amines, and preparation of derivatives of amide compounds.

[0102] According to the present invention, when the silicon-aluminum-based metal catalyst provided by the present invention is used in the above-mentioned application, the conversion rate of the raw materials and the selectivity of the target product can be effectively improved, thereby improving the yield of the target product.

[0103] A fourth aspect of the present invention provides a method for preparing dimethylaminocaprolactam, comprising: contacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of a catalyst and a solvent and performing a hydrogenation reaction to obtain dimethylaminocaprolactam;

[0104] Wherein, the catalyst is selected from the silicon-aluminum-based metal catalyst provided in the first aspect, or the silicon-aluminum-based metal catalyst prepared by the preparation method provided in the second aspect.

[0105] In some embodiments of the present invention, preferably, the conditions for the hydrogenation reaction include: a temperature of 30-150°C, preferably 80-120°C; a time of 0.5-16 hours, preferably 1-3 hours; and a hydrogen pressure of 0.1-10 MPa, preferably 0.5-5 MPa. In the present invention, unless otherwise specified, pressure refers to gauge pressure.

[0106] In some embodiments of the present invention, preferably, the weight ratio of aminocaprolactam and / or its derivatives to formaldehyde and / or its derivatives is 1:0.2-2, for example, 1:0.2, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:1, 1:1.2, 1:2, and any value in the range consisting of any two values, preferably 1:0.4-0.6.

[0107] In some embodiments of the present invention, preferably, the aminocaprolactam and / or its derivatives are selected from aminocaprolactam and / or aminocaprolactam salts, preferably at least one selected from DL-α-amino-ε-caprolactam, DL-α-amino-ε-caprolactam hydrochloride, DL-α-amino-ε-caprolactam sulfate and DL-α-amino-ε-caprolactam nitrate.

[0108] In some embodiments of the present invention, preferably, the formaldehyde and / or its derivatives are selected from formaldehyde and / or formaldehyde polymers; the formaldehyde polymers are selected from trioxymethylene and / or paraformaldehyde.

[0109] In some embodiments of the present invention, preferably, the weight ratio of the aminocaprolactam and / or its derivatives to the catalyst is 1:0.01-10, for example, 1:0.01, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:5, 1:10, and any value in the range of any two values, preferably 1:0.1-5, more preferably 1:0.5-2.

[0110] In some embodiments of the present invention, preferably, the ratio of the aminocaprolactam and / or its derivatives in g to the solvent in mL is 1:20-200, for example, 1:20, 1:40, 1:50, 1:80, 1:100, 1:150, 1:200, and any value in the range consisting of any two values, preferably 1:40-100.

[0111] In some embodiments of the present invention, preferably, the solvent is selected from organic compounds, preferably at least one selected from organic alcohols, heteroatom-containing cycloalkanes and aromatic hydrocarbons.

[0112] In a specific embodiment of the present invention, preferably, the organic alcohol is selected from C1-C5 organic alcohols, including but not limited to methanol, 1-pentanol, and 1-hexanol; the heteroatom-containing cycloalkanes include but are not limited to 1,4-dioxane and tetrahydrofuran; and the aromatic hydrocarbons include but are not limited to benzene and toluene.

[0113] According to a particularly preferred embodiment of the present invention, a silica-alumina-based metal catalyst for preparing dimethylaminocaprolactam comprises a carrier and an active component supported on the carrier, wherein the carrier is selected from modified alumina having a B acid density of 0-0.5 μmol / g and an L acid density of 150-250 μmol / g, the modified alumina having a silicon-aluminum ratio of less than 1, silicon in the modified alumina being bonded to the surface of the alumina via Si-O-Al chemical bonds, and adjacent silicon on the surface of the alumina being bonded via Si-O-Si chemical bonds; wherein the active component is selected from Pt and / or Pd; and the dispersion of the active component is 20-80%.

[0114] Wherein, the specific surface area of the modified alumina is 220-280m 2 / g; average pore size of 70-120nm; wear index of 0.1-6%; crushing strength of 150-280N / cm;

[0115] Wherein, the modified alumina is prepared by the following method:

[0116] (1) an aluminum source, an acidic compound, a regulating agent and water are first mixed to obtain a first mixture; (2) the first mixture is sequentially molded, first dried and first calcined to obtain a molded alumina; (3-i) a first silicon source, a cluster regulating agent and a first solvent are second mixed so that the silicon source and the cluster regulating agent are in a metastable state in the first solvent, and the obtained metastable mixture is used to wash the molded alumina to obtain a modified alumina precursor; or, (3-ii) the molded alumina is dissolved in water, an alkaline compound is added to adjust the pH to 8-12, and then a mixture containing a second silicon source, a dispersant and a second solvent is added and ultrasonically mixed to obtain a second mixture, which is then solid-liquid separated to obtain a modified alumina precursor; (4) the modified alumina precursor is sequentially second dried and second calcined to obtain a modified alumina;

[0117] Wherein, based on the total weight of the modified alumina, SiO x The silicon content is 20-30wt%, wherein 1≤x≤2; the aluminum oxide content is 70-80wt%; the impurity content is 0-100ppm in terms of elements, and the impurities are selected from alkali metals and / or alkaline earth metals.

[0118] The present invention will be described in detail below through examples.

[0119] The parameters of Br(OH)2O3 and L(OH)2O3 are calculated based on the amount of pyridine desorbed by temperature increase; that is, Br(OH)2O3 density = the amount of Br(OH)2O3 of the modified alumina measured by pyridine infrared spectrum (in μmol) / the mass of the modified alumina (in g); L(OH)2O3 density = the amount of Br(OH)2O3 of the modified alumina measured by pyridine infrared spectrum (in μmol) / the mass of the modified alumina (in g);

[0120] The specific surface area parameters were measured using a fully automatic isothermal adsorption instrument;

[0121] Silicon and aluminum contents were measured using X-ray fluorescence;

[0122] The average pore size parameters were obtained using a fully automatic isothermal adsorption instrument and the BJH model.

[0123] Wear index parameters were measured using a wear index analyzer;

[0124] Crushing strength parameters were measured using a particle strength tester;

[0125] The particle size parameters of the cluster particles were determined using a dynamic light scattering particle size analyzer.

[0126] The physical properties of the modified aluminas (S1-S16 and DS1-DS8) prepared in Examples 1-16 and Comparative Examples 1-8 are listed in Table 1.

[0127] Example 1

[0128] (1) 80 g of aluminum source (pseudo-boehmite), 5 g of acidic compound aqueous solution (30 wt% dilute nitric acid solution), 2 g of carbon quantum dots (with a diameter of 1.2 nm and a carboxyl group density of 113 μmol / m 2 ) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 25° C., rotation speed of 600 rpm, time of 1 h) to obtain a first mixture;

[0129] (2) spray drying the first mixture (temperature: 100° C., time: 5 h), and then calcining in a muffle furnace at 800° C. for 3 h to obtain microspherical alumina;

[0130] (3) 120 g of silicon source (ethyl orthosilicate), 15 g of cluster regulator (geraniol) and 500 g of deionized water were mixed for a second time (temperature of 1 ° C., rotation speed of 1200 rpm, time of 2 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted into the above-mentioned formed alumina at a pressure of 3 mL / min and 1.5 MPa, and the sieve plate collected the second mixture after elution, and the elution liquid was collected below the sieve plate;

[0131] (4) The modified alumina precursor was dried with a microwave at a power of 500 W for 20 min; and then calcined in a muffle furnace at 600° C. for 3 h in static air to obtain microspherical modified alumina S1 as a carrier;

[0132] (5) A chloropalladium acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated onto the surface of the support using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1 wt%. The catalyst precursor was dried at 100°C for 5 h in a forced air drying oven and then calcined at 500°C for 3 h in a muffle furnace to obtain a microspherical catalyst Pd / S-1.

[0133] Among them, the transmission infrared spectrum of the modified alumina S1 is as follows Figure 1 As shown in (a), Figure 1 (a) It can be seen that the wave number is 1066cm -1 and 1160cm -1 The signal peaks at the positions are the vibration absorption peaks of Si-O-Si and Si-O-Al bonds, respectively, indicating that the silicon in the modified alumina S1 is bonded to the alumina through Si-O-Al chemical bonds, and the adjacent silicon on the surface of the alumina is bonded to the SiO x (1≤x≤2) clusters exist.

[0134] Among them, the pyridine infrared characterization spectrum of the modified alumina S1 is as follows Figure 2 As shown by Figure 2It can be seen that the modified alumina S1 has extremely low B acid sites, that is, the B acid density is 0 μmol / g; and also has certain L acid sites, that is, the L acid density is 137 μmol / g.

[0135] Among them, the XRD pattern of the modified alumina S1 is as follows: Figure 3 As shown by Figure 3 It can be seen that the aluminum oxide in the modified aluminum oxide S1 is γ-alumina.

[0136] Example 2

[0137] (1) 80 g of aluminum source (aluminum oxyhydroxide), 10 g of acidic compound aqueous solution (10 wt% dilute nitric acid solution), 2 g of carbon quantum dots (diameter 1.4 nm, carboxyl group density 176 μmol / m 2 ) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 20° C., rotation speed of 400 rpm, time of 1 h) to obtain a first mixture;

[0138] (2) spray drying the first mixture (temperature: 100° C., time: 5 h), and then calcining in a muffle furnace at 800° C. for 3 h to obtain microspherical alumina;

[0139] (3) 160 g of silicon source (ethyl orthosilicate), 10 g of cluster modifier (citronellol) and 300 g of methanol were mixed for a second time (temperature of -5 ° C, rotation speed of 1600 rpm, time of 3 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted with the above-mentioned formed alumina at a pressure of 0.8 mL / min and 2 MPa, and the sieve plate collected the second mixture after elution, and the elution liquid was collected below the sieve plate;

[0140] (4) drying the modified alumina precursor using a microwave at a power of 700 W for 30 min; and calcining the modified alumina precursor using a muffle furnace at 600° C. in static air for 3 h to obtain microspherical modified alumina S2 as a carrier;

[0141] (5) A chloropalladium acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated onto the surface of the support using an excess impregnation method to obtain a catalyst precursor with a Pd loading of 0.5 wt%. The catalyst precursor was dried at 100°C for 5 h in a forced air drying oven and then calcined at 600°C for 2 h in a muffle furnace to obtain a microspherical catalyst Pd / S-2.

[0142] Example 3

[0143] (1) 100 g of aluminum source (pseudo-boehmite), 4 g of acidic compound aqueous solution (20 wt% dilute nitric acid solution), 8 g of carbon quantum dots (with a diameter of 1.0 nm and a carboxyl group density of 287 μmol / m 2) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 30° C., rotation speed of 400 rpm, time of 1 h) to obtain a first mixture;

[0144] (2) extruding the first mixture and vacuum drying it (at 100° C. for 5 h), and then calcining it in a muffle furnace at 1000° C. for 2 h to obtain strip-shaped alumina;

[0145] (3) 80 g of silicon source (ethyl orthosilicate), 20 g of cluster regulator (nerol) and 200 g of N,N-dimethylformamide were mixed for a second time (temperature of -3 ° C, rotation speed of 1500 rpm, time of 2 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted into the above-mentioned formed alumina at a pressure of 2.2 mL / min and 1.8 MPa, and the sieve plate collected the second mixture after elution, and the elution liquid was collected below the sieve plate;

[0146] (4) The modified alumina precursor was dried using a microwave at a power of 900 W for 5 min; and calcined in a muffle furnace at 600° C. for 3 h in static air to obtain strip-shaped modified alumina S3 as a carrier;

[0147] (5) A palladium ammonia solution was prepared using dilute ammonia water, and Pd was impregnated onto the surface of the above-mentioned carrier using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1 wt%. After drying in a forced air drying oven at 120°C for 5 h, it was calcined in a muffle furnace at 500°C for 3 h to obtain a strip catalyst Pd / S-3.

[0148] Example 4

[0149] (1) 50 g of aluminum source (pseudo-boehmite), 10 g of acidic compound aqueous solution (20 wt% dilute nitric acid solution), 5 g of carbon quantum dots (diameter 1.4 nm, carboxyl density 166 μmol / m 2 ) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 30° C., rotation speed of 400 rpm, time of 1 h) to obtain a first mixture;

[0150] (2) forming the first mixture into balls with oil-ammonia droplets and drying them with blast air (at 100° C. for 5 h), and then calcining them in a muffle furnace at 1000° C. for 2 h in static air to obtain small spherical alumina;

[0151] (3) 60 g of silicon source (triethoxysilane), 2 g of cluster regulator (citral) and 100 g of N, N-dimethyl sulfoxide were mixed for a second time (temperature of -3 ° C, rotation speed of 1700 rpm, time of 3 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted with the above-mentioned formed alumina at a pressure of 2.5 mL / min and 1.5 MPa, and the sieve plate collected the second mixture after elution, and the elution liquid was collected below the sieve plate;

[0152] (4) drying the modified alumina precursor using a microwave at a power of 900 W for 5 min; and calcining the modified alumina S4 using a muffle furnace at 800° C. in static air for 3 h to obtain small spherical modified alumina S4 as a carrier;

[0153] (5) A chloropalladium acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated onto the surface of the support using a deposition precipitation method to obtain a catalyst precursor with a Pd loading of 5 wt%. The catalyst precursor was dried at 120°C for 5 h in a forced air drying oven and then calcined in a muffle furnace at 400°C for 6 h to obtain a spherical catalyst Pd / S-4.

[0154] Example 5

[0155] (1) 80 g of aluminum source (γ-alumina), 5 g of acidic compound aqueous solution (30 wt% dilute hydrochloric acid solution), 6 g of carbon quantum dots (with a diameter of 1.4 nm and a carboxyl group density of 166 μmol / m 2 ) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 30° C., rotation speed of 800 rpm, time of 1 h) to obtain a first mixture;

[0156] (2) spray drying the first mixture (temperature: 100° C., time: 5 h), and then calcining in a muffle furnace at 800° C. for 3 h to obtain microspherical alumina;

[0157] (3) 70 g of silicon source (trimethylsilanol) was mixed with 6 g of cluster modulator (citronellal) and 100 g of N, N-dimethyl sulfoxide for a second time (temperature of 5 ° C., rotation speed of 1900 rpm, time of 2 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted with the above-mentioned formed alumina at a pressure of 0.3 mL / min2 MPa, and the sieve plate collected the second mixture after elution, and the eluent after elution was collected below the sieve plate;

[0158] (4) drying the modified alumina precursor using a microwave at a power of 1200 W for 20 min; and calcining the modified alumina precursor using a muffle furnace at 800° C. in static air for 3 h to obtain microspherical modified alumina S5 as a carrier.

[0159] (5) A chloropalladium acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated onto the surface of the support using a deposition precipitation method to obtain a catalyst precursor with a Pd loading of 0.8 wt%. The catalyst precursor was dried at 120°C for 5 h in a forced air drying oven and then calcined at 600°C for 2 h in a muffle furnace to obtain a microspherical catalyst Pd / S-5.

[0160] Example 6

[0161] (1) 80 g of aluminum source (pseudo-boehmite), 20 g of acidic compound aqueous solution (10 wt% dilute sulfuric acid solution), 8 g of carbon quantum dots (diameter 1.2 nm, carboxyl group density 113 μmol / m 2 ) and 800 mL of water were first mixed in a 1500 mL stirred tank (temperature of 30° C., rotation speed of 800 rpm, time of 1 h) to obtain a first mixture;

[0162] (2) extruding the first mixture and drying it with blast air (at 100° C. for 5 h), and then calcining it in a muffle furnace at 800° C. for 3 h to obtain strip-shaped alumina;

[0163] (3) 30 g of silicon source (ethyl orthosilicate), 2 g of cluster regulator (tagnatone) and 80 g of methanol were mixed for a second time (temperature of -5 ° C, rotation speed of 2000 rpm, time of 3 h) to obtain a metastable mixture; and the above-mentioned metastable mixture was eluted with the above-mentioned formed alumina at a pressure of 1.2 mL / min and 1 MPa, and the sieve plate collected the second mixture after elution, and the elution liquid was collected below the sieve plate;

[0164] (4) The modified alumina precursor was dried with a microwave at a power of 1400 W for 10 min; and then calcined in a muffle furnace at 900° C. for 5 h in static air to obtain strip-shaped modified alumina S6 as a carrier;

[0165] (5) A chloropalladium acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated onto the surface of the support using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1.2 wt%. The catalyst precursor was dried at 100°C for 10 h in a forced air drying oven and then calcined in a muffle furnace at 400°C for 5 h to obtain a microspherical catalyst Pd / S-6.

[0166] Example 7

[0167] The method of Example 1 is as follows, except that

[0168] In step (5), a chloroplatinic acid solution is prepared with deionized water, and Pt is impregnated into the surface of the above-mentioned carrier by an isochoric impregnation method to obtain a catalyst precursor with a Pt loading of 1 wt%. After drying at 120°C in a forced air drying oven for 5 h, the catalyst is calcined in a muffle furnace at 500°C for 3 h to obtain a microspherical catalyst Pt / S-1.

[0169] Example 8

[0170] The method of Example 1 is as follows, except that

[0171] In step (5), a ruthenium chloride solution is prepared using deionized water, and Ru is impregnated into the surface of the above-mentioned carrier by an excess impregnation method to obtain a catalyst precursor with a loading of 6 wt% Ru. After drying in a forced air drying oven at 100°C for 10 hours, the catalyst is calcined in a muffle furnace at 500°C for 3 hours to obtain a microspherical catalyst Ru / S-1.

[0172] Example 9

[0173] The method of Example 1 is as follows, except that

[0174] In step (5), a rhodium chloride solution is prepared with deionized water, and Rh is impregnated into the surface of the above-mentioned carrier by an isochoric impregnation method to obtain a catalyst precursor with a loading amount of 5wt% Rh. The catalyst precursor is dried at 100°C for 8h in a blast drying oven and then calcined at 500°C in a muffle furnace for 3h to obtain a microspherical catalyst Rh / S-1.

[0175] Example 10

[0176] The method of Example 1 is as follows, except that

[0177] In step (5), an iridium acetate solution is prepared using deionized water, and Ir is impregnated into the surface of the above-mentioned carrier by an excess impregnation method to obtain a catalyst precursor with a loading of 2 wt% Ir. After drying in a forced air drying oven at 100°C for 8 h, it is calcined in a muffle furnace at 500°C for 3 h to obtain a microspherical catalyst Ir / S-1.

[0178] Example 11

[0179] According to the method of Example 1, the difference is that

[0180] In step (3), the shaped alumina is dissolved in 800 mL of water, an alkaline compound (ammonia water) is first added to adjust the pH to 10, 60 g of a silicon source (ethyl orthosilicate), 15 g of a dispersant (sodium hexanoate) and 500 g of deionized water are mixed uniformly, and the resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 25° C., power of 100 W, time of 20 min), and the obtained second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0181] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 600° C. for 3 h in static air to obtain modified alumina S11;

[0182] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-11.

[0183] Example 12

[0184] According to the method of Example 2, the difference is that

[0185] In step (3), the shaped alumina is dissolved in 800 mL of water, an alkaline compound (ammonia water) is first added to adjust the pH to 12, 60 g of a silicon source (ethyl orthosilicate), 10 g of a dispersant (potassium decanoate) and 300 g of methanol are mixed uniformly, and the resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 25° C., power of 80 W, time of 12 min), and the obtained second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0186] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 600° C. for 3 h in static air to obtain modified alumina S11;

[0187] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-12.

[0188] Example 13

[0189] The method of Example 3 is followed, except that

[0190] In step (3), the shaped alumina is dissolved in 800 mL of water, an alkaline compound (ammonia water) is added to adjust the pH to 12, 10 g of a silicon source (ethyl orthosilicate), 20 g of a dispersant (sodium heptanoate) and 200 g of N,N-dimethylformamide are mixed uniformly, and the resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 40° C., power of 50 W, time of 20 min), and the obtained second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0191] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 600° C. for 3 h in static air to obtain modified alumina S13;

[0192] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-13.

[0193] Example 14

[0194] The method of Example 4 is as follows, except that

[0195] In step (3), the above-mentioned shaped alumina is dissolved in 800 mL of water, and an alkaline compound (ammonia water) is first added to adjust the pH to 10, 10 g of a silicon source (silicon tetrachloride), 20 g of a dispersant (potassium decanoate) and 100 g of N,N-dimethyl sulfoxide are mixed uniformly, and the resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 25 ° C, power of 80 W, time of 15 min), and the obtained second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0196] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 800° C. for 3 h in static air to obtain modified alumina S14;

[0197] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-14.

[0198] Example 15

[0199] The method of Example 5 is followed, except that

[0200] In step (3), the shaped alumina is dissolved in 800 mL of water, an alkaline compound (ammonia water) is added to adjust the pH to 12, 50 g of a silicon source (silica aerogel), 6 g of a dispersant (sodium octanoate) and 100 g of N,N-dimethyl sulfoxide are mixed uniformly, and the resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 25 ° C, power of 100 W, time of 10 min), and the obtained second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0201] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 800° C. for 3 h in static air to obtain modified alumina S15;

[0202] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-15.

[0203] Example 16

[0204] The method of Example 6 is followed, except that

[0205] In step (3), the shaped alumina is dissolved in 800 mL of water, and an alkaline compound (ammonia water) is first added to adjust the pH to 12. 30 g of a silicon source (ethyl orthosilicate), 2 g of a dispersant (lithium nonanoate) and 80 g of methanol are mixed evenly. The resulting mixture is then ultrasonically mixed with the shaped alumina / ammonia solution (temperature of 60° C., power of 90 W, time of 15 min). The resulting second mixture is subjected to solid-liquid separation to obtain a modified alumina precursor;

[0206] In step (4), the modified alumina precursor is dried in a vacuum drying oven at 100° C. for 5 h, and then calcined in a muffle furnace at 900° C. for 5 h in static air to obtain modified alumina S16;

[0207] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / S-16.

[0208] Comparative Example 1

[0209] 800 mL of deionized water, 80 g of pseudo-boehmite, 2 g of carbon quantum dots (with a diameter of 1.2 nm and a carboxyl group density of 113 μmol / m 2 ) and 10 g of a 10 wt% dilute nitric acid aqueous solution were mixed in a 1500 mL stirred tank (temperature 25° C., rotation speed 800 rpm, time 5 h), the resulting mixture was subjected to solid-liquid separation, the resulting solid was spray-dried, and then calcined in a muffle furnace at 800° C. in static air for 3 h to obtain microspherical modified alumina DS1 as a carrier;

[0210] A chloropalladic acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated into the surface of the above-mentioned carrier using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1 wt%. After drying at 100°C in a forced air drying oven for 5 h, it was calcined in a muffle furnace at 500°C for 3 h to obtain a microspherical catalyst Pd / DS-1.

[0211] The transmission infrared spectrum of the modified alumina DS1 is shown in 1(b); Figure 1 (b) It can be seen that the wave number is 1066cm -1 and 1160cm -1 There are no signal peaks at all, indicating that the silicon in the modified alumina DS1 is not chemically bonded to the alumina, and the adjacent silicon on the surface of the alumina is not chemically bonded either;

[0212] Among them, the pyridine infrared characterization spectrum of the modified alumina DS1 is as follows Figure 2 As shown in Figure 2, it can be seen that the modified alumina DS1 has a relatively high B acid site, that is, the B acid density is 1.5 μmol / g; it also has a certain L acid site, that is, the L acid density is 75 μmol / g.

[0213] Comparative Example 2

[0214] 800 mL of deionized water, 80 g of aluminum source (pseudo-boehmite), 2 g of carbon quantum dots and 20 g of 5 wt% dilute nitric acid aqueous solution were mixed in a 1500 mL stirred tank (temperature 25 ° C, rotation speed 800 rpm, time 5 h), and then a mixture of 120 g of ethyl orthosilicate, 15 g of cluster regulator (geraniol) and 500 g of deionized water was added. The resulting mixture was spray-dried and calcined in a muffle furnace at 800 ° C for 3 h in static air to obtain microspherical modified alumina DS2 as a carrier.

[0215] A chloropalladic acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated into the surface of the above-mentioned carrier using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1 wt%. After drying at 100°C in a forced air drying oven for 5 h, it was calcined in a muffle furnace at 500°C for 3 h to obtain a microspherical catalyst Pd / DS-2.

[0216] Among them, the pyridine infrared characterization spectrum of the modified alumina DS2 is as follows Figure 2 As shown by Figure 2 It can be seen that the modified alumina DS2 has a relatively high B acid site, that is, the B acid density is 7.4 μmol / g; it also has a certain L acid site, that is, the L acid density is 86 μmol / g.

[0217] Among them, the XRD pattern of the modified alumina DS2 is as follows: Figure 3 As shown by Figure 3 It can be seen that the alumina in the modified alumina DS2 is γ-alumina.

[0218] Comparative Example 3

[0219] The method of Example 1 is as follows, except that

[0220] In step (1), 2 g of carbon quantum dots were not added;

[0221] In steps (2)-(4), the other conditions are the same to obtain microspherical modified alumina DS3;

[0222] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / DS-3.

[0223] Comparative Example 4

[0224] The method of Example 1 is as follows, except that

[0225] In step (3), 15 g of cluster modulator (geraniol) was not added;

[0226] In step (4), the other conditions are the same to obtain microspherical modified alumina DS4;

[0227] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / DS-4.

[0228] Comparative Example 5

[0229] 800 mL of deionized water, 80 g of pseudo-boehmite and 20 g of a 5 wt% dilute nitric acid aqueous solution were mixed in a 1500 mL stirred tank (temperature 25 ° C, rotation speed 800 rpm, time 5 h), and then ammonia water was added to adjust the pH to 12. 60 g of ethyl orthosilicate and 15 g of dispersant sodium hexanoate were mixed evenly in 500 g of deionized water, and then mixed with the formed alumina / ammonia solution and stirred at 25 ° C for 12 h. The resulting mixture was spray dried and calcined at 800 ° C in static air in a muffle furnace for 3 h to obtain microspherical modified alumina DS5 as a carrier.

[0230] A chloropalladic acid solution was prepared using dilute hydrochloric acid, and Pd was impregnated into the surface of the above-mentioned carrier using an isochoric impregnation method to obtain a catalyst precursor with a Pd loading of 1 wt%. After drying at 100°C for 5 h in a forced air drying oven, the catalyst was calcined in a muffle furnace at 500°C for 3 h to obtain a microspherical catalyst Pd / DS-5.

[0231] Comparative Example 6

[0232] The method of Example 11 is followed, except that

[0233] In step (3), adjusting the pH to 7;

[0234] In step (4), the other conditions are the same to obtain microspherical modified alumina DS6;

[0235] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / DS-6.

[0236] Comparative Example 7

[0237] The method of Example 11 is followed, except that

[0238] In step (3), 15 g of dispersant (sodium caproate) was not added;

[0239] In step (4), the other conditions are the same to obtain microspherical modified alumina DS7;

[0240] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / DS-7.

[0241] Comparative Example 8

[0242] The method of Example 11 is followed, except that

[0243] In step (3), the filtration and washing conditions are controlled during the solid-liquid separation process so that a small amount of the dispersant sodium hexanoate remains on the surface of the modified alumina, and the sodium ion content of the modified alumina obtained after step (4) is greater than 1000 ppm, thereby obtaining modified alumina DS8;

[0244] In step (5), the remaining conditions are the same to obtain a microspherical catalyst Pd / DS-8.

[0245] Table 1

[0246]

[0247] Note: In the examples and comparative examples, the sum of silicon content, aluminum oxide content and impurity content based on the total weight of modified aluminum oxide is 100 wt%; 1-based on the total weight of modified aluminum oxide, SiO x 1-Si content calculated as 1≤x≤2; 2-Impurity content calculated as elements based on the total weight of the modified alumina, the impurities being selected from alkali metals and / or alkaline earth metals, wt%.

[0248] Table 1

[0249]

[0250] Note: 3- In step (3), the particle size of the cluster particles in the metastable mixture, nm; or, the particle size of the cluster particles in the mixed material, nm.

[0251] It can be seen from the results in Table 1 that compared with Comparative Examples 1-8, the modified alumina prepared in Examples 1-16 has low B acid density, high L acid density, low wear index, high crushing strength, high specific surface area and high average pore size, that is, the modified alumina provided by the present invention has low B acid density, high L acid density, wear resistance, high stability and excellent pore structure.

[0252] Test Example 1

[0253] The catalytic effects of the catalysts prepared in Examples 1-16 and Comparative Examples 1-8 were evaluated using a batch autoclave. The specific operation included: in the presence of 50 mL of methanol and 0.1 g of the catalyst, 0.2 g of aminocaprolactam and 0.1 g of polyformaldehyde were subjected to a hydrogenation reaction, wherein the hydrogenation reaction conditions included: a hydrogen pressure of 0.3 MPa, a temperature of 80° C., and a reaction time of 3 h to obtain a reaction product, wherein the reaction product included dimethylaminocaprolactam, methylaminocaprolactam, and other by-products.

[0254] The catalytic reaction results were analyzed by gas chromatography, and the test results are listed in Table 2.

[0255] Specifically, the reaction product was detected by filtering the reaction solution and the catalyst, adding a certain amount of n-decane as an internal standard, mixing the internal standard with the reaction filtrate, and performing gas phase analysis and quantification (Angilent GC 7890B; separation column: PONA column (0.32 mm × 30 m);

[0256]

[0257] The mass of converted aminocaprolactam = the mass of aminocaprolactam - the residual mass of aminocaprolactam.

[0258]

[0259] Table 2

[0260]

[0261] Note: Conversion rate of 4-aminocaprolactam, %; yield of 5-dimethylaminocaprolactam, %.

[0262] The results in Table 2 show that the modified alumina provided by the present invention is used as a carrier to load the active component, especially the active component Pd, to obtain a catalyst for the hydrogenation reaction of aminocaprolactam and paraformaldehyde, with high raw material conversion and product selectivity, that is, the obtained dimethylaminocaprolactam has a high yield.

[0263] At the same time, compared with Examples 11-16, Example 1-6 uses the modified alumina prepared in step (3-i) as a carrier to load the active component, and the prepared silicon-aluminum-based metal catalyst is used for the hydrogenation reaction of aminocaprolactam and polyformaldehyde, which has higher product selectivity.

[0264] Test Example 2

[0265] According to the method of test example 1, the difference is that

[0266] The catalysts prepared in Examples 1-10 and Comparative Examples 1-2 were subjected to hydrogenation reaction according to the reaction conditions and process parameters in Table 3. The obtained reaction products were analyzed by gas chromatography for catalytic reaction results. The test results are listed in Table 4.

[0267] Table 3

[0268]

[0269] Table 4

[0270]

[0271]

[0272] Note: Conversion rate of 6-aminocaprolactam, %; yield of 7-dimethylaminocaprolactam, %.

[0273] It can be seen from the data in Table 3-4 that, compared with Comparative Examples 1-2, the silicon-aluminum-based metal catalyst provided by the present invention has higher reaction efficiency under specific hydrogen reaction conditions, and improves the selectivity of the target product, thereby improving the yield of the target product.

[0274] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A silicon-aluminum-based metal catalyst, characterized in that The silicon-aluminum-based metal catalyst comprises: a carrier and an active component supported on the carrier, wherein the carrier is selected from modified alumina having a B acid density of 0-2 μmol / g and an L acid density of ≥30 μmol / g, wherein the silicon-aluminum ratio of the modified alumina is less than 1, and silicon in the modified alumina is connected to the surface of the alumina via Si-O-Al chemical bonds, and adjacent silicon on the surface of the alumina is connected via Si-O-Si chemical bonds; The modified alumina is prepared by the following method: (1) an aluminum source, an acidic compound, a regulator and water are first mixed to obtain a first mixture; (2) the first mixture is sequentially molded, first dried and first calcined to obtain a molded alumina; (3-i) a first silicon source, a cluster regulator and a first solvent are second mixed so that the silicon source and the cluster regulator are in a metastable state in the first solvent, and the obtained metastable mixture is used to wash the molded alumina to obtain a modified alumina precursor; or, (3-ii) the molded alumina is dissolved in water, an alkaline compound is added to adjust the pH to 8-12, and then a mixture containing a second silicon source, a dispersant and a second solvent is added for ultrasonic mixing to obtain a second mixture for solid-liquid separation to obtain a modified alumina precursor; (4) the modified alumina precursor is sequentially second dried and second calcined to obtain the modified alumina.

2. The silicon-aluminum-based metal catalyst according to claim 1, wherein The alumina in the modified alumina is γ-alumina, or a mixed crystal phase of γ-alumina and θ-alumina; Preferably, based on the total weight of the modified alumina, SiO x The silicon content is 10-50wt%, preferably 20-30wt%, wherein 1≤x≤2; the aluminum oxide content is 50-90wt%, preferably 70-80wt%; Further preferably, the impurity content in terms of elements is 0-1000 ppm, preferably 0-100 ppm, based on the total weight of the modified alumina, and the impurities are selected from alkali metals and / or alkaline earth metals.

3. The silicon-aluminum-based metal catalyst according to claim 1 or 2, wherein The B acid density of the modified alumina is 0-1.4 μmol / g, more preferably 0-0.5 μmol / g; the L acid density of the modified alumina is 30-500 μmol / g, preferably 100-300 μmol / g, more preferably 120-250 μmol / g; Preferably, the specific surface area of the modified alumina is 180-320m 2 / g, preferably 200-300m 2 / g, more preferably 220-280m 2 / g; average pore size is 30-150nm, preferably 50-120nm, more preferably 70-120nm; wear index is 0.1-20%, preferably 0.1-10%, more preferably 0.1-6%; crushing strength is 50-300N / cm, preferably 100-300N / cm, more preferably 150-280N / cm.

4. The silicon-aluminum-based metal catalyst according to any one of claims 1 to 3, wherein The active component is selected from at least one of Pt, Pd, Rh, Ir, Ru and Ni, preferably Pt and / or Pd; Preferably, the dispersion of the active ingredient is ≥20%, preferably 20-80%; Preferably, based on the total weight of the silicon-aluminum-based metal catalyst, the content of the active component is 0.1-10 wt%, preferably 0.5-5 wt%; the content of the carrier is 90-99.9 wt%, preferably 95-99.5 wt%.

5. A method for preparing a silicon-aluminum-based metal catalyst, characterized in that: The preparation method comprises the following steps: (1) performing a first mixing of an aluminum source, an acidic compound, a regulating agent, and water to obtain a first mixture; (2) subjecting the first mixture to molding, first drying, and first calcination in sequence to obtain molded alumina; (3-i) performing a second mixing of a first silicon source, a cluster modifier, and a first solvent, so that the silicon source and the cluster modifier are in a metastable state in the first solvent, and eluting the formed alumina with the obtained metastable mixture to obtain a modified alumina precursor; or (3-ii) dissolving the formed alumina in water, adding an alkaline compound to adjust the pH to 8-12, and then adding a mixture containing a second silicon source, a dispersant, and a second solvent, performing ultrasonic mixing to obtain a second mixture, performing solid-liquid separation, and obtaining a modified alumina precursor; (4) subjecting the modified alumina precursor to a second drying and a second calcination in sequence, and using the obtained modified alumina as a carrier; (5) A soluble metal salt is loaded on the surface of the carrier, and the obtained catalyst precursor is subjected to a third drying and a third calcination in sequence to obtain a silicon-aluminum-based metal catalyst.

6. The preparation method according to claim 5, wherein In step (1), in the first mixture, the content of the aluminum source is 0.01-10 wt%, preferably 0.05-5 wt%; the content of the acidic compound is 0.01-3 wt%, preferably 0.05-1 wt%; and the content of the regulating agent is 0.01-2 wt%, preferably 0.05-1 wt%; Preferably, the regulator is a carbon quantum dot, and the diameter of the carbon quantum dot is 1-1.5 nm, and the carboxyl density is 2-500 μmol / m 2 , preferably 20-200 μmol / m 2 ; Preferably, the first mixing conditions include: temperature of 15-40°C, preferably 20-30°C; rotation speed of 100-1000 rpm, preferably 300-1000 rpm; time of 0.1-5h, preferably 0.1-2h; Preferably, in step (2), the molding method is selected from oil-ammonia droplet molding, spray drying molding, and extrusion molding; Preferably, the conditions for the first calcination include: a temperature of 700-1500° C., preferably 800-1200° C.; and a time of 1-10 h, preferably 1-5 h.

7. The preparation method according to claim 5 or 6, wherein In step (3-i), The second mixing conditions include: temperature of -10 to 5°C, preferably -8 to 2°C; speed of 800-2000 rpm, preferably 1000-1500 rpm; time of 0.5-5h, preferably 1-4h; Preferably, in the metastable mixture, the particle size of the cluster particles is 1-50 nm, preferably 5-30 nm; Preferably, the mass ratio of the first silicon source, the cluster modifier and the first solvent is 0.1-20:0.1-5:75-99.8, preferably 0.5-15:0.3-2:85-92; Preferably, the first silicon source is a soluble silicon salt, preferably selected from organic silicon salts; Preferably, the cluster regulator is selected from at least one of terpene alcohol compounds, terpene aldehyde compounds and terpene ketone compounds, preferably selected from at least one of citronellol, geraniol, nerol, citral, citronellal and tagetone; Preferably, the first solvent is selected from at least one of water, methanol, N,N-dimethylformamide and N,N-dimethyl sulfoxide; Preferably, the shaped alumina calculated as Al2O3 and the shaped alumina calculated as SiO x The mass ratio of the metastable mixture is 5-9:1-5, preferably 7-8:2-3; wherein 1≤x≤2; Preferably, the elution conditions include: a flow rate of 0.1-10 mL / min, preferably 0.3-3 mL / min; an instrument pump pressure of 0.1-2.5 MPa, preferably 0.3-1.2 MPa; In step (3-ii), Preferably, the pH is adjusted to 10.5-11.5; Preferably, the mass ratio of the second silicon source, the dispersant and the second solvent is 0.1-20:0.1-5:75-99.8, preferably 0.5-15:0.2-3:80-95; Preferably, the second silicon source is a soluble silicon salt, preferably selected from inorganic silicon salts and / or organic silicon salts; Preferably, the dispersant is selected from C4-C 10 The fatty acid salt compound is preferably selected from at least one of sodium hexanoate, potassium octanoate and lithium decanoate; Preferably, the second solvent is selected from at least one of water, methanol, N,N-dimethylformamide and N,N-dimethyl sulfoxide; Preferably, in the mixed material, the particle size of the cluster particles is 1-50 nm, preferably 5-30 nm; Preferably, the shaped alumina calculated as Al2O3 and the shaped alumina calculated as SiO x The mass ratio of the mixed materials is 5-9:1-5, preferably 7-8:2-3; wherein 1≤x≤2; Preferably, the ultrasonic mixing conditions include: temperature of 20-70° C., preferably 25-60° C.; ultrasonic power of 20-200 W, preferably 50-100 W; and time of 1-30 min, preferably 10-20 min.

8. The preparation method according to any one of claims 5 to 7, wherein In step (4), the second drying conditions include: temperature of 80-120°C, time of 90-110°C; time of 1-20h, preferably 1-12h; Preferably, the second drying method is selected from microwave drying, and the microwave drying conditions include: power of 800-2000W, preferably 1000-1500W; time of 2-60min, preferably 5-30min; Preferably, the conditions for the second calcination include: a temperature of 400-1000° C., preferably 500-900° C.; a time of 1-10 h, preferably 1-5 h; Preferably, in step (5), the loading amount of the soluble metal salt calculated as the metal element is 0.1-10 wt%, preferably 0.5-5 wt%; Preferably, the soluble metal salt is selected from hydrochloride, sulfate, nitrate, acetate containing at least one of Pt, Pd, Rh, Ir, Ru and Ni; Preferably, the conditions for the third calcination include: a temperature of 400-800° C., preferably 450-750° C.; and a time of 1-10 h, preferably 1-5 h.

9. Use of the silicon-aluminum-based metal catalyst according to any one of claims 1 to 4, or the silicon-aluminum-based metal catalyst prepared by the preparation method according to any one of claims 5 to 8, in catalyzing the synthesis of lysine-type antibacterial monomers, aminoalkylation reactions of aromatic amines, and preparation of derivatives of amide compounds.

10. A method for preparing dimethylaminocaprolactam, characterized in that: The method comprises: in the presence of a catalyst and a solvent, contacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives and performing a hydrogenation reaction to obtain dimethylaminocaprolactam; Wherein, the catalyst is selected from the silicon-aluminum-based metal catalyst described in any one of claims 1-4, or the silicon-aluminum-based metal catalyst prepared by the preparation method described in any one of claims 5-8.

11. The method according to claim 10, wherein: The conditions of the hydrogenation reaction include: temperature of 30-150°C, preferably 80-120°C; time of 0.5-16h, preferably 1-3h; hydrogen pressure of 0.1-10MPa, preferably 0.5-5MPa; Preferably, the mass ratio of aminocaprolactam and / or its derivatives to formaldehyde and / or its derivatives is 1:0.2-2, preferably 1:0.4-0.6; Preferably, the aminocaprolactam and / or its derivatives are selected from aminocaprolactam and / or aminocaprolactam salts, preferably at least one selected from DL-α-amino-ε-caprolactam, DL-α-amino-ε-caprolactam hydrochloride, DL-α-amino-ε-caprolactam sulfate and DL-α-amino-ε-caprolactam nitrate; Preferably, the formaldehyde and / or its derivatives are selected from formaldehyde and / or formaldehyde polymers, and the formaldehyde polymers are selected from trioxymethylene and / or paraformaldehyde; Preferably, the weight ratio of aminocaprolactam and / or its derivatives to the catalyst is 1:0.01-10, preferably 1:0.1-5, more preferably 1:0.5-2; Preferably, the ratio of the aminocaprolactam and / or its derivatives in g to the solvent in mL is 1:20-200, preferably 1:40-100; Preferably, the solvent is selected from organic compounds, preferably at least one selected from organic alcohols, heteroatom-containing cycloalkanes and aromatic hydrocarbons; More preferably, the organic alcohol is selected from C1-C6 organic alcohols, preferably at least one selected from methanol, 1-pentanol and 1-hexanol; the heteroatom-containing cycloalkane is selected from 1,4-dioxane and / or tetrahydrofuran; and the aromatic hydrocarbon is selected from benzene and / or toluene.

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