Process for the preparation of dimethylaminocaprolactam and its use, cleaning / disinfecting material

Abstract

The present application relates to the technical field of organic synthesis, in particular to a preparation method of dimethylaminocaprolactam and application thereof, and a cleaning / sterilization material containing a polymer of the dimethylaminocaprolactam. The method comprises: contacting and reacting aminocaprolactam and / or a derivative thereof with formaldehyde and / or a derivative thereof in the presence of an optional catalyst and a solvent to obtain dimethylaminocaprolactam. The dimethylaminocaprolactam prepared by the method can be used to prepare a cleaning / sterilization material as a lysine type antibacterial monomer.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a method for preparing dimethylaminocaprolactam and its application, and a cleaning / sterilizing material containing the dimethylaminocaprolactam polymer. Background Technology

[0002] In recent years, polymer materials with self-cleaning / antibacterial functions have become an important development trend in scientific research and industrialization due to their intrinsic antibacterial properties and good mechanical properties. The synthesis of antibacterial monomers is a key step in the research and development and promotion of such self-cleaning / antibacterial polymer materials. Among them, derivatives of the lysine-type antibacterial monomer aminocaprolactam are considered to have significant research value and development potential.

[0003] CN111116472A discloses a method for preparing an aminocaprolactam derivative, which includes: an organic synthesis method using a haloalkane as an α-amino derivatizing agent and a heterogeneous catalytic method using formaldehyde as an α-amino derivatizing agent under hydrogen conditions, wherein the catalyst used in the heterogeneous catalytic method is Pd / C, and the loading of Pd is 10wt%.

[0004] CN104387323A discloses a method for preparing an aminocaprolactam derivative with a halotoluene derivative as an α-amino substituent; CN103694174A discloses a method for preparing an aminocaprolactam derivative with a benzaldehyde derivative as an α-amino substituent, using NaBH4 or NaBH3CN as the hydrogenation reagent in the system.

[0005] While the above methods have promoted the development of lysine-based antibacterial monomer synthesis routes to some extent, they have the following problems: (1) Halogenated compounds are highly toxic and have poor chemical stability. When used as α-amino derivatization reagents, their efficiency is low, and they cause serious environmental pollution; (2) When aldehydes are used as alkylating reagents, the reaction system needs to be hydrogen-bearing. Boronides, as hydrogenating reagents, have problems such as high cost, low safety, and environmental pollution. Currently, the commercially available Pd / C catalysts have excessively high Pd loading and high catalyst costs, which are not conducive to the industrial implementation of the reaction routes. Therefore, developing efficient and low-cost catalysts is of great significance for promoting the development of lysine-based antibacterial monomer catalytic synthesis systems. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low catalyst efficiency, harsh reaction conditions, low safety, environmental pollution, and high catalyst cost in existing processes for preparing lysine-type antibacterial monomers (i.e., caprolactam and its derivatives). This invention provides a method for preparing dimethylaminocaprolactam and its application, as well as a cleaning / sterilizing material containing the dimethylaminocaprolactam polymer. This method effectively improves the raw material conversion rate and the selectivity of the target product. Furthermore, the dimethylaminocaprolactam obtained by this method can be used as a polymer monomer for preparing cleaning / sterilizing materials.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing dimethylaminocaprolactam, the method comprising: contacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of an optional catalyst and solvent and reacting them to obtain dimethylaminocaprolactam.

[0008] Preferably, the weight ratio of aminocaprolactam and / or its derivatives to formaldehyde and / or its derivatives is 1:0.2-2.

[0009] Preferably, the catalyst comprises a support and an active component supported on the support; based on the total weight of the catalyst, the content of the support is 90-99.9 wt%; and the content of the active component is 0.1-10 wt%.

[0010] Preferably, the carrier is selected from at least one of activated carbon, oxides, and modified oxides.

[0011] Preferably, the modified oxide is selected from silicon-modified alumina with a Brønsted acid density ≤ 2 μmol / g.

[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] Preferably, the reaction conditions include: a temperature of 30-150℃; a time of 0.5-16h; and a hydrogen pressure of 0.1-10MPa.

[0015] The second aspect of this invention provides the application of dimethylaminocaprolactam prepared by the method provided in the first aspect as a polymer monomer in the preparation of cleaning / sterilizing materials.

[0016] A third aspect of the present invention provides a cleaning / sterilizing material containing dimethylaminocaprolactam prepared by the preparation method provided in the first aspect.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The method for preparing dimethylaminocaprolactam provided by the present invention uses aminocaprolactam and / or its derivatives and formaldehyde and / or its derivatives as raw materials, and combines them with optional catalysts and solvents, which can effectively improve reaction efficiency and product selectivity; in particular, by adjusting the support and active components in the catalyst, limiting the Brønsted acid density of a specific support and the dispersion of a specific active component, as well as the weight ratio of each material and the reaction conditions, the catalytic efficiency is further improved; at the same time, the method simplifies the process flow, is easy to operate, environmentally friendly, and is convenient for industrial production.

[0019] (2) The dimethylaminocaprolactam prepared by the preparation method provided by the present invention can be used as a lysine-type antibacterial monomer to prepare cleaning / sterilizing materials. Attached Figure Description

[0020] Figure 1 This is a TEM characterization image of the catalyst Pd / AS-1 prepared in Preparation Example 1.

[0021] Figure 2 The infrared characterization spectra of the pyridine support in the catalysts prepared in Preparation Examples 1 and 9-10 are shown, with a wavenumber of 1540 cm⁻¹. -1 The absorption peak at that location indicates the Brønsted acid site on the support surface.

[0022] Figure 3 (a) is the transmission infrared spectrum of the support AS-1 prepared in Example 1; Figure 3 (b) Transmission infrared spectrum of the carrier Ac-9 prepared in Example 9, 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

[0023] 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.

[0024] 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.

[0025] The first aspect of the present invention provides a method for preparing dimethylaminocaprolactam, the method comprising: contacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of an optional catalyst and solvent and reacting them to obtain dimethylaminocaprolactam.

[0026] 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, 1:0.8, 1:1, 1:1.5, 1:2, and any value within the range of any two values, preferably 1:0.4-0.6. Using these preferred conditions, by controlling the molar ratio of aminocaprolactam and / or its derivatives to formaldehyde and / or its derivatives to be close to 1:2, it is more advantageous to obtain a high yield of the amino-disubstituted product.

[0027] In this invention, unless otherwise specified, the aminocaprolactam and / or its derivatives are selected from aminocaprolactam and / or aminocaprolactam derivatives; similarly, the formaldehyde and / or its derivatives are selected from formaldehyde and / or formaldehyde derivatives.

[0028] In some embodiments of the present invention, preferably, the aminocaprolactam and / or its derivatives are selected from aminocaprolactam and / or aminocaprolactam salts, and more preferably from at least one of DL-α-amino-ε-caprolactam, DL-α-amino-ε-caprolactam hydrochloride, DL-α-amino-ε-caprolactam sulfate and DL-α-amino-ε-caprolactam nitrate.

[0029] In some embodiments of the present invention, preferably, the formaldehyde and / or its derivatives are selected from formaldehyde and / or formaldehyde polymers; wherein the formaldehyde exists in the form of an aqueous solution, and the concentration of formaldehyde in the aqueous formaldehyde solution is 0.5-50 wt%; the formaldehyde polymer is selected from trioxymethylene and / or paraoxymethylene; wherein the weight-average molecular weight of the paraoxymethylene is 1000-3000 g / mol.

[0030] In some embodiments of the present invention, preferably, the weight ratio of the aminocaprolactam and / or its derivatives to the catalyst is 1:0-10, for example, 1:0, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:8, 1:10, and any value within any range of two such values, preferably 1:0.1-5, more preferably 1:0.5-2. Using these preferred conditions is more conducive to improving reactant conversion and target product selectivity.

[0031] In this invention, the catalyst is a conventional catalyst in the art. Preferably, the catalyst comprises a support and an active component supported on the support; based on the total weight of the catalyst, the content of the support is 90-99.9 wt%, preferably 95-99.5 wt%; and the content of the active component is 0.1-10 wt%, preferably 0.5-5 wt%.

[0032] In some embodiments of the present invention, preferably, the support is selected from at least one of activated carbon, oxides and modified oxides; more preferably, the oxides include, but are not limited to, ZnO, TiO2, ZrO2 and CeO2.

[0033] 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.

[0034] In some embodiments of the present invention, preferably, the dispersion of the active component is ≥20%, more preferably 20-80%.

[0035] In some embodiments of the present invention, preferably, the modified oxide is selected from silicon-modified alumina with a Brønsted acid density ≤ 2 μmol / g; more preferably, 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.

[0036] 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 confining the silicon to the alumina surface through Si-O-Al chemical bonds, and further confining adjacent silicon atoms to the alumina surface through Si-O-Si chemical bonds, the acidic sites on the alumina surface can be effectively masked while ensuring that the silicon-modified alumina possesses low wear index, high crushing strength, high specific surface area, and low average pore size. This allows for the control of the Brønsted acid (B acid) density on the silicon-modified alumina surface, resulting in a B acid density ≤2 μmol / g.

[0037] In this invention, unless otherwise specified, the silicon in the silicon-modified alumina is connected to the surface of the alumina via Si-O-Al chemical bonds, meaning that Si and Al in the alumina share the O portion, thereby achieving SiO2. x Silicon, in its present form, is anchored to the surface of the alumina.

[0038] In this invention, unless otherwise specified, the density of Brønsted acid refers to... Acid density.

[0039] In this invention, the Brønsted acid density parameter is calculated based on the amount of pyridine desorbed by heating; 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).

[0040] 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.

[0041] In some embodiments of the present invention, preferably, the specific surface area of ​​the silicon-modified alumina is 100-220 m² / g. 2 / g, preferably 120-200m 2 / g; average pore size is 10-30nm, preferably 15-25nm; wear index is 1-20%, preferably 1-15%; crushing strength is 50-150N / cm, preferably 70-130N / cm.

[0042] 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.

[0043] In some embodiments of the present invention, based on the total weight of the silicon-modified alumina, the alumina content is 50-90 wt%, preferably 70-80 wt%; with SiO x The silicon content is calculated to be 10-50 wt%, preferably 20-30 wt%, wherein 1 ≤ x ≤ 2. Using these preferred conditions is more conducive to reducing the Brønsted acid density of the modified alumina.

[0044] 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%.

[0045] 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.

[0046] 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.

[0047] In this invention, the preparation method of the silicon-modified alumina has a wide range of options, as long as the silicon-modified alumina meets the above-mentioned parameter limitations. Preferably, the silicon-modified alumina is prepared by the following method:

[0048] (1) The aluminum source, the acidic compound and water are mixed in a first mixture to obtain a first mixture;

[0049] (2) The first mixture is subjected to molding, first drying and first calcination in sequence to obtain molded alumina;

[0050] (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;

[0051] (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 to obtain the silicon-modified alumina.

[0052] 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.

[0053] 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.

[0054] 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%.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] In some embodiments of the present invention, preferably, the pH condition is 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.

[0062] 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.

[0063] 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.

[0064] In this invention, unless otherwise specified, solubility means being easily soluble in water, or being easily soluble in water with the help of additives.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] In this invention, the preparation method of the catalyst has a wide range of options, as long as the catalyst meets the above-mentioned limitations. Preferably, the catalyst preparation includes: loading a soluble metal salt onto the surface of the support, and subjecting the obtained catalyst precursor to a third drying and a third calcination to obtain the catalyst.

[0072] In some embodiments of the present invention, preferably, the loading of the soluble metal salt, based on the metal element, is 0.1-10 wt%, more preferably 0.5-5 wt%.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] In some embodiments of the present invention, preferably, the soluble metal salt is selected from hydrochlorides, sulfates, nitrates, and acetates containing at least one of Pt, Pd, Rh, Ir, Ru, and Ni, and more preferably from nitrates, sulfates, and nitrates 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] In some embodiments of the present invention, preferably, the weight ratio of the aminocaprolactam and / or its derivatives to the solvent is 1:20-200, for example, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1:200, and any value within the range of any two values, preferably 1:40-100.

[0082] In some embodiments of the present invention, preferably, the solvent is selected from organic compounds, and more preferably from at least one of organic alcohols, heteroatom-containing cycloalkanes, and aromatic hydrocarbons.

[0083] In one 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.

[0084] In one specific embodiment of the present invention, preferably, the heteroatom-containing cycloalkanes include, but are not limited to, 1,4-dioxane and tetrahydrofuran.

[0085] In one specific embodiment of the present invention, preferably, the aromatic hydrocarbon includes, but is not limited to, benzene and toluene.

[0086] In some embodiments of the present invention, preferably, the reaction conditions include: a temperature of 30-150°C, more preferably 80-120°C; a time of 0.5-16 h, more preferably 1-3 h; and a hydrogen pressure of 0.1-10 MPa, more preferably 0.5-5 MPa. Unless otherwise specified, all pressures in this invention refer to gauge pressure.

[0087] The second aspect of this invention provides the application of methylaminocaprolactam prepared by the preparation method provided in the first aspect as a polymer monomer in the preparation of cleaning / sterilizing materials.

[0088] The methylaminocaprolactam prepared by the method provided in this invention is a lysine-type antibacterial monomer and can be used to prepare cleaning / sterilizing materials.

[0089] A third aspect of the present invention provides a cleaning / sterilizing material containing dimethylaminocaprolactam prepared by the preparation method provided in the first aspect.

[0090] According to a particularly preferred embodiment of the present invention, a method for preparing dimethylaminocaprolactam involves contacting and reacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of a catalyst and methanol to obtain dimethylaminocaprolactam.

[0091] The catalyst comprises a support and an active component supported on the support, wherein the support is silicon-modified alumina, and the active component has a content of 0.5-5 wt% and a dispersion of 20-80%.

[0092] The silicon-modified alumina has a Brønsted acid density of 0-0.5 μmol / g, and comprises silicon and alumina. The silicon-aluminum ratio of the silicon-modified alumina is <1, and 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.

[0093] Wherein, 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.

[0094] The present invention will be described in detail below through embodiments.

[0095] The physical properties of the catalysts prepared in Examples 1-19 are listed in Table 1.

[0096] Preparation Example 1

[0097] (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;

[0098] (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.

[0099] (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;

[0100] (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.

[0101] (5) A Pd(NH3)4Cl2 solution prepared with 30wt% ammonia water was 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 500℃ for 3h under static air to obtain microspherical catalyst Pd / AS-1.

[0102] 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;

[0103] The infrared characterization spectrum of pyridine support AS-1 in catalyst Pd / AS-1 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the carrier AS-1 has extremely low Brønsted acid sites;

[0104] The transmission infrared spectrum of carrier AS-1 is as follows: Figure 3 As shown in (a); by Figure 3 From (a), we can see that the wavenumber is 1066 cm⁻¹. -1 and 1160cm -1The signal peaks at these locations are vibrational absorption peaks of Si-O-Si and Si-O-Al bonds, respectively, indicating that silicon in the support AS-1 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.

[0105] Preparation Example 2

[0106] (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;

[0107] (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.

[0108] (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;

[0109] (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.

[0110] (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.

[0111] Preparation Example 3

[0112] (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;

[0113] (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.

[0114] (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;

[0115] (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.

[0116] (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.

[0117] Preparation Example 4

[0118] (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;

[0119] (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.

[0120] (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;

[0121] (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.

[0122] (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.

[0123] Preparation Example 5

[0124] (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;

[0125] (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.

[0126] (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;

[0127] (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.

[0128] (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.

[0129] Preparation Example 6

[0130] (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;

[0131] (2) The first mixture was spray-dried (at 100°C for 5 hours) and then calcined in a muffle furnace at 900°C for 3 hours under static air to obtain micro-spherical alumina.

[0132] (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;

[0133] (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.

[0134] (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.

[0135] Preparation Example 7

[0136] (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;

[0137] (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.

[0138] (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;

[0139] (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.

[0140] (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.

[0141] Preparation Example 8

[0142] (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;

[0143] (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.

[0144] (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;

[0145] (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.

[0146] (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.

[0147] Preparation Example 9

[0148] 800 mL of deionized water, 80 g of boehmite, and 10 g of 10 wt% dilute nitric acid 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 the support Ac-9. A Pd(NH3)4Cl2 solution was prepared with 30 wt% ammonia water and impregnated onto the surface of the above support using an excess impregnation method to obtain a catalyst precursor with a loading of 1 wt% Pd. After drying in a vacuum drying oven at 100℃ for 5 h, it was calcined in a muffle furnace under static air at 500℃ for 3 h to obtain the microspherical catalyst Pd / Ac-9.

[0149] The pyridine infrared characterization spectrum of Ac-9 support in catalyst Pd / Ac-9 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the carrier Ac-9 has a high number of Brønsted acid sites.

[0150] The transmission infrared spectrum of the carrier Ac-9 is as follows: Figure 3 As shown in (b); by Figure 3 From (b), we can see that the wavenumber 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 Ac-9 carrier.

[0151] Preparation Example 10

[0152] 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 modified alumina as a carrier Ac-10.

[0153] 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 500℃ under static air for 3h to obtain microspherical catalyst Pd / Ac-10.

[0154] The pyridine infrared characterization spectrum of the Ac-10 support in the Pd / Ac-10 catalyst is shown below. Figure 2 As shown, by Figure 2 It can be seen that the carrier Ac-10 has a high number of Brønsted acid sites.

[0155] Preparation Example 11

[0156] The method is the same as in Example 1, except that the active component is different, that is, in step (5),

[0157] A Pd(NH3)4Cl2 solution was prepared by adding 5 wt% ammonia water and impregnated onto the surface of the above support by excess impregnation method to obtain a catalyst precursor with a loading of 1 wt% Pd. After drying in a vacuum drying oven at 100℃ for 5 h, it was calcined in a muffle furnace under static air at 500℃ for 3 h to obtain microspherical catalyst Pd / AS-1.

[0158] Preparation Example 12

[0159] The method is the same as in Example 1, except that the active component is different, that is, in step (5),

[0160] A 10wt% RuCl3 solution was prepared by deionizing water and impregnated onto the surface of the above support by saturation impregnation to obtain a catalyst precursor with a loading of 1wt% Ru. After drying in a vacuum drying oven at 100℃ for 5h, it was calcined in a muffle furnace under static air at 500℃ for 3h to obtain the microspherical catalyst Ru / AS-1.

[0161] Preparation Example 13

[0162] The method is the same as in Example 1, except that the active component is different, that is, in step (5),

[0163] A 25wt% Ni(NO3)2 solution was prepared by deionized water and impregnated onto the surface of the above support by deposition precipitation method to obtain a catalyst precursor with a loading of 1wt% Ni. 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 Ni / AS-1.

[0164] Preparation Example 14

[0165] The method is the same as in Example 1, except that the active component is different, that is, in step (5),

[0166] A 20wt% RhCl3 solution was prepared by deionized water and impregnated onto the surface of the above support using an excess impregnation method to obtain a catalyst precursor with a loading of 1wt% Rh. After drying in a vacuum drying oven at 100℃ for 5h, it was calcined in a muffle furnace under static air at 500℃ for 3h to obtain the microspherical catalyst Rh / AS-1.

[0167] Preparation Example 15

[0168] A 30wt% Pd(NH3)4(NO3)2 solution was prepared by deionized water and impregnated onto the ZnO surface using an excess impregnation method to obtain a catalyst precursor with a loading of 1wt% Pd. After drying in a forced-air drying oven at 100℃ for 5h, the precursor was calcined in a tube furnace at 400℃ for 3h under H2 / N2 atmosphere to obtain the Pd / ZnO catalyst.

[0169] Preparation Example 16

[0170] A Pd(NH3)4Cl2 solution prepared with 20wt% ammonia was impregnated onto the surface of CeO2 using an excess impregnation method to obtain a catalyst precursor with a loading of 0.1wt% Pd. After drying in a forced-air drying oven at 100℃ for 5h, it was calcined in a tube furnace at 500℃ for 3h under N2 atmosphere to obtain the catalyst Pd / CeO2.

[0171] Preparation Example 17

[0172] A PdCl2 solution prepared with 37wt% hydrochloric acid was impregnated onto the surface of TiO2 using an excess impregnation method to obtain a catalyst precursor with a loading of 2wt% Pd. After drying in a forced-air drying oven at 100℃ for 5h, it was calcined in a muffle furnace under static air at 400℃ for 3h to obtain the catalyst Pd / TiO2.

[0173] Preparation Example 18

[0174] A 30wt% Pd(NH3)4(NO3)2 solution prepared with deionized water was impregnated onto the surface of ZrO2 using an excess impregnation method to obtain a catalyst precursor with a loading of 1wt% Pd. After drying in a forced-air drying oven at 100℃ for 5h, it was calcined in a muffle furnace under static air at 500℃ for 3h to obtain the catalyst Pd / ZrO2.

[0175] Preparation Example 19

[0176] A 3PdCl2 solution prepared with 37wt% hydrochloric acid was impregnated onto the surface of activated carbon using an excess impregnation method to obtain a catalyst precursor with a loading of 1wt% Pd. After drying in a forced-air drying oven at 100℃ for 5h, it was calcined in a tube furnace at 500℃ for 3h under N2 atmosphere to obtain the catalyst Pd / C.

[0177] Table 1

[0178]

[0179]

[0180] Note: *- indicates silicon content expressed in SiO₂. x Calculate, where 1≤x≤2.

[0181] Continued from Table 1

[0182]

[0183] As can be seen from the results in Table 1, compared with Preparation Examples 9-10 and 15-19, the catalysts prepared in Preparation Examples 1-8 and 11-14 all had silicon-modified alumina as the support. Furthermore, the silicon-modified alumina met specific structural requirements, namely, the silicon-to-alumina ratio of the silicon-modified alumina was <1, and the silicon in the silicon-modified alumina was connected to the surface of the alumina by Si-O-Al chemical bonds, with adjacent silicon atoms on the surface of the alumina connected by Si-O-Si chemical bonds. It also had lower Brønsted acid density, lower wear index, better crushing strength, better specific surface area, and better average pore size.

[0184] Example 1

[0185] In the presence of 50 mL methanol and 0.1 g catalyst Pd / AS-1, 0.2 g aminocaprolactam and 0.1 g paraformaldehyde (weight average molecular weight of 2000 g / mol) were reacted in a batch high-pressure reactor. The reaction conditions included a temperature of 80 °C, a hydrogen pressure of 1 MPa, and a reaction time of 1 h. The reaction products included dimethylaminocaprolactam, methylaminocaprolactam, and other byproducts.

[0186] The reaction conditions and process parameters are listed in Table 2; the catalytic reaction results were analyzed by gas chromatography and the test results are listed in Table 3.

[0187] Specifically, the detection of reaction products involves filtering and separating the reaction solution and 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 (0.32mm×30m)).

[0188]

[0189] Wherein, the mass of converted aminocaprolactam = mass of aminocaprolactam – remaining mass of aminocaprolactam.

[0190]

[0191] Yield of dimethylaminocaprolactam = conversion of aminocaprolactam × selectivity of dimethylaminocaprolactam × 100%.

[0192] Example 2-12

[0193] According to Example 1, the difference lies in the type of catalyst and the process parameters, namely,

[0194] The catalyst in Example 1 was replaced with the catalysts in Preparation Examples 9-19, and the process parameters in Example 1 were replaced with the process parameters in Table 2. The test results are listed in Table 3.

[0195] Table 2

[0196]

[0197] Table 3

[0198]

[0199]

[0200] Note: 1- refers to the conversion rate of aminocaprolactam, %; 2- refers to the yield of dimethylaminocaprolactam, %.

[0201] As shown in Table 2-3, the preparation method of dimethylaminocaprolactam provided by this invention has a high raw material conversion rate and product selectivity. In particular, by adjusting the type of support and the content of active components in the catalyst, as well as the ratio of reactants, it is more conducive to improving the catalytic effect of the catalyst and obtaining a high yield of dimethylaminocaprolactam.

[0202] Comparing the data from Examples 4-7, it can be seen that selecting Pd as the active component in the catalyst is more beneficial for improving the selectivity and yield of dimethylaminocaprolactam.

[0203] Comparing Examples 4 and 8-12, it can be seen that when the catalyst support is silicon-modified alumina with a Brønsted acid density ≤2 μmol / g, it is more conducive to improving the conversion rate of aminocaprolactam, as well as the selectivity and yield of dimethylaminocaprolactam.

[0204] Examples 13-20

[0205] According to Example 1, the difference lies in the process parameters, namely,

[0206] The process parameters of Example 1 were replaced with the process parameters in Table 4, and the test results are listed in Table 5.

[0207] Table 4

[0208]

[0209] Table 5

[0210]

[0211] Note: 1- refers to the conversion rate of aminocaprolactam, %; 2- refers to the yield of dimethylaminocaprolactam, %.

[0212] As can be seen from the data in Table 4-5, compared with Examples 13-16 which used non-methanol solvents, Example 1 used methanol as a solvent, which effectively improved the conversion rate of aminocaprolactam and the selectivity of dimethylaminocaprolactam, thereby improving the yield of dimethylaminocaprolactam.

[0213] As shown in Tables 4-5, compared with Examples 17-20, Example 1, by controlling the reaction conditions within the preferred range (i.e., reaction temperature of 80-120℃, time of 1-3h, and hydrogen pressure of 0.5-5MPa), effectively improved the conversion rate of aminocaprolactam and the selectivity of dimethylaminocaprolactam, thereby increasing the yield of dimethylaminocaprolactam.

[0214] 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 method for preparing dimethylaminocaprolactam, characterized in that, The method includes: contacting and reacting aminocaprolactam and / or its derivatives with formaldehyde and / or its derivatives in the presence of a catalyst and a solvent to obtain dimethylaminocaprolactam; The catalyst comprises a support and an active component supported on the support; based on the total weight of the catalyst, the content of the support is 90-99.5 wt%; and the content of the active component is 0.5-10 wt%. The active component is selected from at least one of Pd, Ru, and Ni; The carrier is selected from modified oxides; the modified oxide is selected from silicon-modified alumina with a Brønsted acid density of 0-0.2 μmol / g and a specific surface area of ​​100-220 m². 2 / g, average pore size is 10-30nm, wear index is 1-20%, crushing strength is 50-150N / cm; 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. 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; The silicon-modified alumina 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 obtained silicon-modified alumina precursor is subjected to a second drying and a second calcination to obtain the silicon-modified alumina; The aminocaprolactam and / or its derivatives are selected from at least one of DL-α-amino-ε-caprolactam, DL-α-amino-ε-caprolactam hydrochloride, DL-α-amino-ε-caprolactam sulfate and DL-α-amino-ε-caprolactam nitrate. The formaldehyde and / or its derivatives are selected from formaldehyde and / or formaldehyde polymers; the formaldehyde polymers are selected from trioxymethylene and / or paraoxymethylene. The solvent is selected from organic alcohols; the organic alcohol is selected from methanol; The reaction conditions include: temperature of 80-150℃; time of 0.8-16h; and hydrogen pressure of 0.5-10MPa.

2. The preparation method according to claim 1, wherein, The weight ratio of aminocaprolactam and / or its derivatives to formaldehyde and / or its derivatives is 1:0.4-0.

6.

3. The preparation method according to claim 1, wherein, The weight ratio of the aminocaprolactam and / or its derivatives to the catalyst is 1:0.5-2.

4. The preparation method according to claim 1, wherein, Based on the total weight of the catalyst, the content of the support is 95-99.5 wt%; the content of the active component is 0.5-5 wt%.

5. The preparation method according to claim 1, wherein, The dispersion of the active component is ≥20%.

6. The preparation method according to claim 5, wherein, The dispersion of the active component is 20-80%.

7. The preparation method according to claim 1, wherein, 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.

8. The preparation method according to claim 1, wherein, The weight ratio of the aminocaprolactam and / or its derivatives to the solvent is 1:20-200.

9. The preparation method according to claim 8, wherein, The weight ratio of the aminocaprolactam and / or its derivatives to the solvent is 1:40-100.

10. The preparation method according to claim 1, wherein, The reaction conditions include: a temperature of 80-120℃; a time of 1-3 hours; and a hydrogen pressure of 0.5-5 MPa.

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