N-alkylation catalyst, preparation method therefor and use thereof

Abstract

The present invention relates to an N-alkylation catalyst, a preparation method therefor and a use thereof. The catalyst comprises a molecular sieve, an oxide binder and a modification component, the modification component being loaded on the molecular sieve and the oxide binder, the modification component comprising Cu and P, and the medium-strong acid content of the catalyst accounting for 35% or more of the total acid content. By means of controlling the order of addition of raw materials in a catalyst preparation process, and selecting Cu and P for synergistic modification, an N-alkylation catalyst having high activity, high stability, extended service life, and good recycling performance can be obtained. The catalyst is used to produce N,N-dimethylaniline, and can reduce side reactions, enable an N-alkylation reaction to operate stably for a long period, and expand a workable reaction temperature range, facilitating continuous industrial production.

Description

N-alkylation catalyst and its preparation method and application Technical Field

[0001] The present invention relates to an N-alkylation catalyst, a preparation method thereof and application thereof in the synthesis of N,N-dimethylaniline (DMA). Background Art

[0002] As an important chemical raw material or intermediate, N,N-dimethylaniline is widely used in a variety of fields, including papermaking, textile dyes, pharmaceuticals, fragrances, and explosives. For example, it can be used as a dye intermediate, solvent, stabilizer, and analytical reagent. In the pharmaceutical industry, it is used to manufacture drugs such as cephalosporin V, sulfamethoxazole, sulfamethoxazole, and flusporin. In the fragrance industry, it is used to manufacture fragrances such as vanillin. Furthermore, it can be used as a curing agent for epoxy resins, a curing accelerator for polyester resins, and a co-catalyst for the polymerization of vinyl compounds. With the development and innovation of the chemical industry, the application areas of N,N-dimethylaniline are continuously expanding, and market demand is also showing a positive growth trend.

[0003] DMA is primarily synthesized through the N-alkylation of aniline. Currently, the main methods for this reaction include the liquid-phase method, typically catalyzed by sulfuric acid, and the gas-phase method, typically catalyzed by solid acids. The sulfuric acid-catalyzed liquid-phase method is the mainstream technology for industrial DMA production. DMA is produced in a batch-type process by reacting aniline with methanol in an autoclave under high temperature and pressure. This method offers advantages such as high conversion and a mature process. However, it suffers from poor continuous production capacity, high equipment investment (due to the reaction being carried out in the presence of a liquid acid catalyst and under high pressure, corrosion- and pressure-resistant equipment and materials are required), severe environmental pollution (e.g., the production process produces a large amount of acid-soluble oil, and the product separation requires the use of large amounts of liquid caustic soda to neutralize the inorganic acid, resulting in a large amount of difficult-to-handle inorganic salts), and high subsequent processing costs. Therefore, the development of efficient, environmentally friendly, and green processes for the synthesis of DMA has become a hot topic of research.

[0004] The vapor-phase method synthesizes DMA via the vapor-phase alkylation reaction of aniline with methanol using metal oxides, metal salts, and molecular sieves as catalysts. Although this method has been studied in India and other locations, its relatively low product selectivity (approximately 90%, lower than that of liquid-phase methods) has limited its industrial application. However, the potential for continuous production and low waste generation of this method offers a new approach to the green synthesis of DMA. In recent years, technological advances and catalyst improvements have improved the selectivity and yield of this method, making it an increasingly important method for preparing DMA.

[0005] In China, a lot of research has also been done on the vapor phase synthesis of N,N-dimethylaniline. Wu Kerui et al. (Petrochemical Engineering, 1988, 17(3): 135-137) reported that the modified ZSM-5 was used as a catalyst to react aniline with methanol at atmospheric pressure, reaction temperature of 300℃, and liquid space velocity of 1.0h. -1 The selectivity of DMA was 88% under the conditions of aniline to methanol molar ratio of 1:3. Li Guotao et al. (Petrochemical Engineering, 2002, 31(2):81-83) used β molecular sieve as catalyst, and the reaction temperature was 240-250℃ and the space velocity was 0.5h -1 Under the conditions of , the feedstock conversion rate is approximately 99%, and the product selectivity is 85%. However, the reactant conversion and product selectivity in the above-mentioned literature are still relatively low, and the conversion and selectivity decrease rapidly as the reaction proceeds. Improving the selectivity and stability of the catalyst is a challenge that needs to be addressed in molecular sieve catalysts used in the synthesis of DMA via N-alkylation.

[0006] From a reaction mechanism perspective, the alkylation of methanol and aniline to N,N-dimethylaniline typically occurs at temperatures of 300°C, and water molecules are generated during the reaction. Molecular sieves are susceptible to dealumination in the presence of high temperatures and water, leading to permanent deactivation of the catalyst, significantly impacting the conversion rate, selectivity, and stability of the catalyst. Furthermore, carbon deposition on the catalyst begins with the alkylation of N,N-dimethylaniline and methanol to form the byproduct N,N,C-trimethylaniline. Further reactions occur, including hydrogen transfer, alkylation, and cyclization, resulting in the formation of non-volatile, multi-ring carbon deposits. This carbon deposit, known as hard coke, typically requires high-temperature oxidative roasting to remove. However, high-temperature oxidative roasting damages the catalyst structure, reducing its acid content and, consequently, its activity and stability.

[0007] Researchers have attempted to improve the activity and stability of catalysts through methods such as phosphorus modification. Generally speaking, existing phosphorus modification methods are mostly focused on molecular sieve modification. A small number of literature reports on phosphorus modification of catalysts after forming. However, this catalyst phosphorus modification method is relatively complex and requires phosphorus modification and re-calcination after the catalyst is calcined. Multiple calcinations not only have a significant impact on the activity of the catalyst, but also increase the complexity of the catalyst preparation process and high energy consumption. Therefore, there is a need to develop catalysts that are efficient, stable, simple to prepare, and have low energy consumption.

[0008] The vapor-phase synthesis of N,N-dimethylaniline still faces numerous challenges, including improving the catalytic performance and stability of catalysts, as well as ensuring process economics and environmental friendliness. By developing new, efficient, and stable catalysts, exploring simpler and more controllable catalyst modification methods, optimizing reaction conditions, and establishing a continuous, low-energy production process, the sustainable development of N,N-dimethylaniline production is expected to be achieved, providing strong support for the transformation and upgrading of related industries.

[0009] Summary of the Invention

[0010] The present invention aims to address the technical problems encountered in the prior art vapor-phase synthesis of N,N-dimethylaniline, including low catalytic efficiency, poor catalyst stability, high costs, and environmental pollution. To address these technical issues, the present invention provides a novel N-alkylation catalyst, its preparation method, and its application. The N-alkylation catalyst is simple to prepare and, when used in the vapor-phase synthesis of N,N-dimethylaniline, exhibits excellent stability, high reactant conversion, high selectivity for the target product, a wide applicable reaction temperature range, and ease of separation from the product, thereby facilitating the green and efficient production of N,N-dimethylaniline.

[0011] In a first aspect, the present invention provides an N-alkylation catalyst, characterized in that the catalyst comprises a molecular sieve, an oxide binder and a modifying component, the modifying component is loaded on both the molecular sieve and the oxide binder, the modifying component comprises Cu and P, the percentage of the medium-strong acid content of the catalyst to the total acid content is not less than 35%, preferably not less than 40%, more preferably not less than 42%, and the percentage of the medium-strong acid content to the total acid content is calculated as the percentage of the desorption peak area at 250°C-450°C measured by the NH3 programmed temperature desorption method to the desorption peak area of ​​the total acid content.

[0012] In some embodiments, the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 type molecular sieve, β-type molecular sieve, MCM-22 type molecular sieve and mordenite type molecular sieve, preferably at least one of Y-type molecular sieve, ZSM-5 type molecular sieve and β-type molecular sieve, more preferably β-type molecular sieve. In some embodiments, the oxide binder is aluminum oxide and / or silicon oxide. In some embodiments, the Cu:P molar ratio n(CuO):n(P2O5) in terms of oxide in the catalyst is 30:1-1:25, preferably 20:1-1:10. In some embodiments, the mass ratio of the molecular sieve to the oxide binder is 95:5-20:80, preferably 90:10-25:75. In some embodiments, the Cu in the catalyst is 0.1% to 0.1%; + / Cu 2+The ratio is 0-0.4, preferably 0.1-0.35. In some embodiments, the pyridine infrared L acid content of the catalyst accounts for more than 60% of the total pyridine infrared acid content, preferably 65-80%. In some embodiments, the modifying component further comprises a metal M component selected from at least one of Group VIII metals and Group VIB metals; preferably, the metal M component is selected from at least one of Cr, Zn, Fe and Ni, more preferably selected from at least one of Cr, Zn and Ni.

[0013] In a second aspect, the present invention provides a method for preparing the above-mentioned N-alkylation catalyst, comprising:

[0014] 1) mixing a molecular sieve and an oxide binder to obtain a mixture;

[0015] 2) The mixture obtained in step 1) is mixed with a solution containing a copper precursor and a phosphorus-containing compound, and then formed, and then calcined once to obtain a catalyst.

[0016] In some embodiments, in step 1), the oxide binder is a solid oxide binder or a sol-state oxide binder, preferably a sol-state oxide binder. In some embodiments, in step 1), the oxide binder is alumina and / or silica. In some embodiments, in step 1), the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve, and mordenite, preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve, and β-type molecular sieve, more preferably β-type molecular sieve. In some embodiments, in step 2), the copper precursor is selected from soluble copper compounds, preferably selected from at least one of cupric chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate. In some embodiments, in step 2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, a soluble phosphate, and a phosphite; preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate. In some embodiments, in step 2), the mass ratio of the copper precursor to the phosphorus-containing compound, calculated as the element, is 5:95-98:2, preferably 30:70-80:20; preferably, the mass ratio of the oxide binder to the copper precursor, calculated as the element, is 80:20-99.9:0.1, preferably 85:15-99:1. In some embodiments, in step (2), the calcination conditions include: a temperature of 450-800°C, preferably 500-700°C; and a calcination time of 1-15 hours, preferably 1-12 hours.

[0017] In some embodiments, when a sol-state oxide binder is used in step 1), the method further comprises: introducing a peptizing agent into a solution containing a copper precursor and a phosphorus-containing compound, mixing the mixture with the mixture obtained in step 1), and then forming the mixture; preferably, the peptizing agent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid; preferably, the amount of the peptizing agent is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4.

[0018] In some embodiments, the method further comprises: 3) performing an activation treatment on the catalyst obtained in step 2) to obtain an activated catalyst; preferably, the activation treatment is performed under an activation atmosphere, preferably the activation atmosphere is selected from at least one of hydrogen, CO, ammonia and hydrogen sulfide, more preferably hydrogen; preferably, the conditions of the activation treatment include: a temperature of 150-600°C, preferably 200-400°C; a time of 0.5-30h, preferably 2-24h; a flow rate of the activation atmosphere of 0.001-100mL / min / g catalyst, preferably 0.01-50mL / min / g catalyst.

[0019] In some embodiments, step (2) of the method further comprises: introducing a metal M component precursor and mixing it with the mixture obtained in step 1), a copper precursor and a phosphorus-containing compound. Preferably, the mass ratio of the metal M component precursor to the copper precursor, calculated as elements, is 1:50-1:1, preferably 1:25-1:2; preferably, the metal M component precursor is selected from a soluble compound of at least one of Group VIII metals and Group VIB metals, preferably selected from a soluble compound of at least one of Cr, Zn, Fe and Ni, more preferably selected from at least one of chromium chloride, chromium nitrate, zinc nitrate, zinc sulfate, nickel nitrate, nickel nitrate, basic nickel carbonate, nickel acetate, nickel sulfate, ferric nitrate, ferrous chloride and ferric chloride.

[0020] In a third aspect, the present invention also provides an N-alkylation catalyst obtained by the preparation method according to the second aspect.

[0021] In a fourth aspect, the present invention further provides use of the N-alkylation catalyst according to the first aspect or the N-alkylation catalyst obtained by the preparation method according to the second aspect in the N-alkylation reaction of aniline, particularly in the production of N,N-dimethylaniline by the N-alkylation reaction of aniline.

[0022] In a fifth aspect, the present invention provides a method for producing N,N-dimethylaniline, comprising reacting methanol and aniline in the presence of a catalyst to produce N,N-dimethylaniline, wherein the reaction is a gas phase reaction; wherein the catalyst is the N-alkylation catalyst according to the first aspect or the N-alkylation catalyst obtained by the preparation method according to the second aspect.

[0023] In some embodiments, the reaction conditions include: a molar ratio of methanol to aniline of 1-10:1, preferably 2-8:1; a reaction temperature of 180-350°C, preferably 220-300°C; a mass space velocity of methanol and aniline of 0.1-10h -1 , preferably 0.5-4.5h -1 .

[0024] The N-alkylation catalyst provided by the present invention is synergistically modified by introducing Cu and P. On the one hand, the acid distribution in the catalyst can be adjusted, the acidity ratio of medium and strong acids in the catalyst can be increased, the acidity ratio of strong acids can be reduced, and the adsorption of methanol with high polarity at acidic sites can be reduced, thereby reducing the occurrence of side reactions and improving the catalytic performance of the catalyst, such as the reactant conversion rate and the target product selectivity. On the other hand, the hydrothermal stability and / or recycling performance of the catalyst can be improved, the applicable reaction temperature range of the N-alkylation reaction can be broadened, and the long-term operation of the N,N-dimethylaniline production process can be achieved, which is conducive to industrial continuous production and greatly saves production costs.

[0025] The N-alkylation catalyst provided by the present invention is further + / Cu 2+ The ratio of 2:1 to 1:1 significantly improves the activity, stability, and life of the catalyst. In addition, the variable-valence metal selected as the metal M component itself has multiple valence states, which can also reduce the retention of the target product at the acidic site, further improving the life of the catalyst.

[0026] The method for preparing an N-alkylation catalyst provided by the present invention controls the order of adding raw materials during the catalyst preparation process, strictly follows the steps of first mixing the molecular sieve and the oxide binder, directly mixing them with a solution containing a copper precursor, a phosphorus-containing compound, and other components without calcination, and then forming the mixture. The mixture is then subjected to a single calcination and a preferred activation treatment to obtain the catalyst. Only one calcination is required during the catalyst preparation process, thus avoiding the multiple calcinations required for modification after catalyst formation in the prior art, reducing the acid loss caused by multiple calcinations, lowering the difficulty of the catalyst preparation process, and reducing energy consumption. Furthermore, through the activation treatment, the catalyst is provided with a specific range of Cu + / Cu 2+ The activity, stability and life of the catalyst are significantly improved.

[0027] The present invention provides a method for producing N,N-dimethylaniline. By employing a catalyst with high activity, high stability, extended life, and good recyclability, the method reduces side reactions, enables long-term stable operation of the N-alkylation reaction, and broadens the applicable reaction temperature, facilitating industrial continuous production. Furthermore, the method is environmentally friendly, with a recyclable catalyst and zero pollution and emissions during the production process.

[0028] Other features and advantages of the present application will be described in detail in the subsequent detailed description. DETAILED DESCRIPTION

[0029] The specific implementation methods of the present application are described in detail below. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0030] Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, any combination of the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be used to generate one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0031] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0032] N-alkylation catalysts

[0033] As described above, in a first aspect, the present invention provides an N-alkylation catalyst, characterized in that the catalyst comprises a molecular sieve, an oxide binder and a modifying component, the modifying component is loaded on both the molecular sieve and the oxide binder, the modifying component comprises Cu and P, and the percentage of the medium-strong acid content of the catalyst to the total acid content is not less than 35%, preferably not less than 40%, and more preferably not less than 42%.

[0034] In the present invention, the catalyst acid distribution is characterized using the NH3 temperature-programmed desorption method (NH3-TPD). The characterization method is as follows: Instrument: Quantachrome Chemstar TPx; Testing process: Weigh 0.15g (formed and ground to 20-40 mesh) of molecular sieve or catalyst sample, heat it to 550°C, dry it, and then cool it to 100°C to allow the catalyst to saturate with NH3. The temperature is then raised to 250°C, 350°C, 450°C, and 550°C to desorb NH3, and the NH3 concentration is detected using a TCD detector. The adsorption curves obtained at different temperature ranges are integrated, and the instrument automatically calculates the acid density distribution at different temperatures. The acid content obtained by integrating at 150-250°C is weak acid, at 250-450°C is medium-strong acid, and at 450-550°C is strong acid; and at 150-550°C is the total acid content.

[0035] In some embodiments, the percentage ratio of the medium-strong acid amount of the catalyst to the total acid amount can be 35%-50%, preferably 40%-50%, more preferably 42%-50%. For example, the percentage ratio of the medium-strong acid amount of the catalyst to the total acid amount can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% or even higher, or can be in the range of being composed of any two of the above values. The catalyst according to the present invention has a higher medium-strong acid amount ratio. The medium-strong acid site of the catalyst can reduce the adsorption of methanol with larger polarity at the acid site, reducing the generation of side reactions. On the other hand, the increased medium-strong acid amount ratio of the catalyst makes it possible to maintain high conversion at a reduced reaction temperature, thereby further suppressing the generation of side reactions at high temperatures, reducing carbon deposition, and extending catalyst life.

[0036] In some embodiments, the percentage ratio of the strong acid amount of the catalyst to the total acid amount can be 5%-9%, preferably 5%-8.8%. For example, the percentage ratio of the medium-strong acid amount of the catalyst to the total acid amount can be 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5% or even lower, or can be within the range of any two of the above values. The catalyst according to the present invention has a lower strong acid amount ratio. The strong acid sites of the catalyst can promote further undesirable side reactions in the target product. Therefore, the reduced catalyst strong acid amount ratio makes it possible to reduce side reactions and improve the selectivity and stability of the catalyst.

[0037] In some embodiments, the molecular sieve is selected from at least one of a Y-type molecular sieve, a ZSM-5 type molecular sieve, a β-type molecular sieve, an MCM-22 type molecular sieve, and a mordenite type molecular sieve, preferably at least one of a Y-type molecular sieve, a ZSM-5 type molecular sieve, and a β-type molecular sieve. In a particularly preferred embodiment, the molecular sieve in the catalyst according to the present invention is a β-type molecular sieve, which exhibits high reactant conversion and high target product selectivity when used to produce N,N-dimethylaniline via an N-alkylation reaction, and has an extended catalyst life.

[0038] In some embodiments, the oxide binder is aluminum oxide and / or silicon oxide. The present invention further increases the total acid content and the ratio of medium-strong acid content of the catalyst by simultaneously modifying both the molecular sieve and the oxide binder, which is particularly beneficial for achieving the purposes of the present invention (e.g., improving the stability, catalytic performance, and service life of the catalyst).

[0039] In some embodiments, the mass ratio of the molecular sieve to the oxide binder is 95:5-20:80, preferably 90:10-25:75. For example, the mass ratio of the molecular sieve to the oxide binder can be 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, or can be within a range consisting of any two of the above values.

[0040] In some embodiments, the molar content of Cu in the catalyst calculated as CuO is 0.01-10%, preferably 0.1-5%. For example, the molar content of Cu in the catalyst calculated as CuO can be 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or can be within a range consisting of any two of the above values.

[0041] In some embodiments, the molar content of P in the catalyst calculated as P2O5 is 0.01-20%, preferably 0.05-15%. For example, the catalyst may have a molar content of P, calculated as PO, of 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, or can be within a range consisting of any two of the foregoing values.

[0042] In some embodiments, the Cu:P molar ratio, calculated as oxide, of the catalyst, n(CuO):n(PO), is from 30:1 to 1:25, preferably from 20:1 to 1:10. For example, the Cu:P molar ratio, calculated as oxide, of the catalyst, n(CuO):n(PO), can be 30:1, 25:1, 20:1, 15:1, 10:1, 5:1, 2:1, 1:1, 1:2, 1:5, 1:10, 1:15, 1:20, 1:25, or a range consisting of any two of the foregoing values.

[0043] By controlling the Cu content, P content and / or Cu:P molar ratio in the catalyst, the acid distribution in the catalyst can be adjusted, and the proportion of medium and strong acids can be increased, thereby improving the activity, hydrothermal stability and / or recyclability of the catalyst.

[0044] In some preferred embodiments, the Cu in the catalyst + / Cu 2+ The ratio of Cu in the catalyst is 0-0.4, preferably 0.1-0.35. + / Cu 2+ The ratio of can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or can be within the range consisting of any two of the above values. The catalyst according to the present invention preferably has a specific Cu + / Cu 2+ The advantage of adopting such a preferred embodiment is that Cu + / Cu 2+ The ratio of Cu to aniline within a specific range can effectively reduce the adsorption capacity of aniline at acid sites, reduce the formation of carbon precursors, and improve catalyst stability. + / Cu 2+The ratio is usually greater than 1.5. + / Cu 2+ When the ratio of is not within the above range, the adsorption capacity of the acidic sites for aniline cannot be reduced, which is not conducive to improving the stability of the catalyst.

[0045] It should be noted that in the present invention, Cu + / Cu 2+ The ratio refers to the Cu + and Cu 2+ The ratio of content.

[0046] In the present invention, Cu + / Cu 2+ The ratio is determined using the chemical adsorption module of the American Micromeritics ASAP 2460 adsorption instrument. The specific test conditions are as follows:

[0047] (a) Catalyst pretreatment: 0.2 g of catalyst sample was pretreated at 330 °C in vacuum for 10 h to remove impurities on the catalyst surface;

[0048] (b) Carbon monoxide adsorption: Using carbon monoxide gas as the adsorption medium, at 25°C and a relative pressure range of p / p0 = 0.05-0.65, the sample after impurities removal in step (a) was subjected to carbon monoxide adsorption, and the total adsorption isotherm was measured. The total adsorption area was then calculated according to the BET equation, and the total adsorption area was calculated as Cu + and Cu 2+ Total content A;

[0049] (c) Carbon monoxide desorption: vacuum to 10 at 25 °C -6 Pa, under this condition, the sample was subjected to carbon monoxide desorption after adsorption in step (b), the desorption isotherm (reversible adsorption isotherm) was measured, and then the desorption area (reversible adsorption area) was calculated according to the BET equation. + The adsorbed carbon monoxide will not desorb, and the desorption area (reversible adsorption area) is calculated as Cu 2+ Content A1;

[0050] (d) Calculate the irreversible adsorption area A2 = A-A1, and calculate the irreversible adsorption area as Cu + The content A2, and then calculate the ratio of A2 / A1, so Cu + / Cu 2+ =A2 / A1.

[0051] In some embodiments, a variable valence metal selected from at least one of Group VIII metals and Group VIB metals can be suitable for use in the present invention as the metal M component. Preferably, the metal M component is selected from at least one of Cr, Zn, Fe, and Ni, and more preferably selected from at least one of Cr, Zn, and Ni. Preferably, the metal M component is present in the catalyst in an amount of 0.01-5% by mole, preferably 0.05-2% by mole, based on the total weight of the catalyst, as an oxide. For example, in some embodiments, the metal M component is present in the catalyst in an amount of 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% by mole, as an oxide, or in a range consisting of any two of the above values.

[0052] In the present invention, the Cu and metal M components in the catalyst cooperate with each other to increase the proportion of L acid and maintain Cu + / Cu 2+ The ratio is within a specific range, reduces the adsorption of the reaction raw materials with larger polarity at the acidic site, reduces the occurrence of side reactions, and improves the life of the catalyst. Preferably, the pyridine infrared α-acid amount of the catalyst accounts for more than 60% of the pyridine infrared total acid amount, more preferably 65-80%. For example, in some embodiments, the pyridine infrared α-acid amount of the catalyst can account for 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80% of the pyridine infrared total acid amount, or can be within the range of being composed of any two of the above values.

[0053] In the present invention, the pyridine infrared acid content of the catalyst is determined using a Bruker Tensor II Fourier transform infrared spectrometer. The specific test process is as follows: about 25 mg of the catalyst sample is pressed into a pellet at 20 MPa for 5 minutes. The pellet has a diameter of 1.4 cm and is placed in an in-situ cell of the infrared spectrometer and sealed. The temperature is raised to 450°C at a rate of 10°C / min and the temperature is evacuated to 10 -6 Pa for 2 h, cooled to room temperature, statically saturated with pyridine, then vacuumed, and gradually heated to 200 ° C and 350 ° C to desorb the adsorbed pyridine. The infrared spectra at the two temperatures were measured and integrated. - 1 The absorption peak at Acidic site (B acid), 1450 cm -1 The absorption peak is attributed to the Lewis acid site (L acid), wherein the acid amount of B acid and L acid is calculated by the following formula:

[0054] C B =1.88AB R 2 / W

[0055] C L =1.42A L R 2 / W

[0056] C represents the concentration of B acid or L acid (mmol / g);

[0057] A represents the integrated area of ​​the absorption peak of B acid or L acid;

[0058] R represents the radius of the sample piece (cm);

[0059] W represents the mass of the sample piece (mg).

[0060] In the present invention, the content of each component in the catalyst is calculated using X-ray fluorescence spectrometry (X-ray Fluorescence Spectrometry, referred to as XRF) and combined with the feed amount. The instrument used for X-ray fluorescence spectrometry is a ZSX-2 X-ray fluorescence spectrometer produced by Rigaku Electric Co., Ltd. of Japan. The experimental parameters are set as follows: a rhodium target is used, the excitation voltage is set to 40kV, and the excitation current is set to 40mA to ensure the stability and accuracy of the excitation source; sample processing and test conditions: the sample is processed in powder form, a tight tablet is formed by pressing, and the external pressure range is generally set to 500-1000KPa to ensure that the sample surface is flat and uniform, which is conducive to the effective penetration of X-rays and the accurate collection of fluorescence signals; data analysis process: first, the standard sample is measured, and a detailed working curve is constructed according to the measurement results. Then, the fluorescence intensity of the unknown sample is located on the working curve by interpolation, thereby calculating the content of each component in the sample.

[0061] In the present invention, when referring to the content of components, unless otherwise specified, they are all calculated as oxides, for example, Cu is calculated as CuO, P is calculated as P2O5, Cr is calculated as Cr2O3, Zn is calculated as ZnO, Fe is calculated as Fe2O3, and Ni is calculated as NiO.

[0062] In the present invention, the catalyst contains micropores and mesopores. It should be noted that the mesopores of the catalyst refer to pores with a pore diameter of 2-50 nm, and the micropores refer to pores with a pore diameter of less than 2 nm.

[0063] In some embodiments, the mesopore volume of the catalyst accounts for 30-55% of the total pore volume, more preferably 40-50%. In some embodiments, the micropore volume of the catalyst is 0.05-0.3 cm 3 / g, more preferably 0.1-0.2cm 3In some embodiments, the mesopore volume of the catalyst is 0.05-0.3 cm 3 / g, more preferably 0.05-0.25cm 3 In some embodiments, the total pore volume of the catalyst is 0.15-0.6 cm 3 / g, more preferably 0.15-0.45cm 3 / g.

[0064] In the present invention, the pore volume of the catalyst is determined by the BET method using a Micromeritics ASAP 2460 multi-station surface area and porosity analyzer. The specific test process is as follows: the catalyst sample is vacuumed to 10 at 330°C. -3 Pa, and then maintained at low temperature for 9 hours to remove water and other impurities adsorbed on the catalyst. The specific surface area and micropore area of ​​the sample were calculated using the BET (Brunauer-Emmett-Teller) method; the desorption data were calculated using the BJH (Barrett-Joyner-Halenda) method to obtain the pore structure parameters of the sample.

[0065] The N-alkylation catalyst provided by the invention is modified by introducing Cu and P to adjust the acid distribution in the catalyst, thereby improving the catalytic performance, hydrothermal stability and / or recycling performance of the catalyst; by adjusting Cu + / Cu 2+ The ratio of 2:1 to 1:2 can further significantly improve the activity, stability and life of the catalyst, thereby broadening the applicable reaction temperature range of the N-alkylation reaction and realizing the long-term operation of the N,N-dimethylaniline production process, which is conducive to industrial continuous production and greatly saves production costs.

[0066] Preparation method of N-alkylation catalyst

[0067] In a second aspect, the present invention provides a method for preparing the above-mentioned N-alkylation catalyst, comprising:

[0068] 1) mixing a molecular sieve and an oxide binder to obtain a mixture;

[0069] 2) The mixture obtained in step 1) is mixed with a solution containing a copper precursor and a phosphorus-containing compound, and then formed, and then calcined once to obtain a catalyst.

[0070] In some embodiments, in step 1), the oxide binder is a solid oxide binder or a sol-state oxide binder, preferably a sol-state oxide binder. In a particularly preferred embodiment, in step 1), the oxide binder is a sol-state oxide binder, such as alumina sol and / or silica sol. Sol-state oxide binders help improve dispersibility, achieving better mixing and more uniform distribution of the molecular sieve and the oxide binder in the catalyst, strengthening interaction, and improving catalyst stability and catalytic performance.

[0071] In the present invention, the concentration of the sol-state oxide binder is not particularly limited. Preferably, the concentration of the sol-state oxide binder can be 0.1-50 wt%, more preferably 10-30 wt%. Preferably, the pH of the sol-state oxide binder can be 1-5, for example, 1, 2, 3, 4, 5, or within a range consisting of any two of the aforementioned values. Preferably, the average particle size of the sol-state oxide binder is 0.1-300 nm.

[0072] In some embodiments, in step 1), the oxide binder is aluminum oxide and / or silicon oxide. In the present invention, there is no particular limitation on the types of precursors of aluminum oxide and silicon oxide, and any substance that can be converted into aluminum oxide and / or silicon oxide by calcination as conventionally defined in the art can be applied to the present invention. In some embodiments, in step 1), the oxide binder is aluminum oxide. Preferably, the aluminum oxide is provided by at least one of pseudo-boehmite, aluminum chloride, aluminum hydroxide and aluminum sol. In some embodiments, when a sol-state oxide binder is used in step 1), the oxide binder is aluminum sol and / or silica sol.

[0073] In some embodiments, in step 1), the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve, and mordenite, preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve, and β-type molecular sieve, more preferably β-type molecular sieve. In some embodiments, in step 1), the silicon-aluminum molar ratio n(SiO2):n(Al2O3) of the molecular sieve is 2-1000:1, preferably 2-100:1. In some embodiments, the average particle size of the molecular sieve is 0.01-50 μm, preferably 0.1-20 μm.

[0074] In some embodiments, in step 1), the mass ratio of the molecular sieve to the oxide binder is 95:5-20:80, preferably 90:10-25:75. For example, in step 1), the mass ratio of the molecular sieve to the oxide binder can be 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, or can be within a range consisting of any two of the foregoing values.

[0075] In the present invention, there is no particular limitation on the type of copper precursor, as long as it can provide copper. In some embodiments, in step 2), the copper precursor is selected from soluble copper compounds. Preferably, the copper precursor is selected from at least one of cupric chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate.

[0076] In the present invention, there is no particular limitation on the type of phosphorus-containing compound, as long as it can provide phosphorus. In some embodiments, in step 2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, a soluble phosphate, and a phosphite. Preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate. In some embodiments, the phosphorus-containing compound is provided in the form of an aqueous solution of the phosphorus-containing compound. Preferably, the concentration of the aqueous solution of the phosphorus-containing compound is 0.01-25wt%, preferably 5-25wt%.

[0077] In some embodiments, in step 2), the mass ratio of the copper precursor to the phosphorus-containing compound, calculated as the elements, is 5:95-98:2, preferably 30:70-80:20. By controlling the amounts of the copper precursor and the phosphorus-containing compound, the acid distribution in the catalyst can be adjusted, increasing the proportion of medium and strong acids, thereby improving the activity, hydrothermal stability, and / or recyclability of the catalyst.

[0078] In some embodiments, the mass ratio of the oxide binder to the copper precursor, calculated on an element basis, is 80:20-99.9:0.1, preferably 85:15-99:1.

[0079] In some embodiments, when the oxide binder is in a sol state, a peptizing agent is introduced to peptize it. Preferably, when a sol-state oxide binder is used in step 1), the method further comprises: introducing a peptizing agent into a solution containing a copper precursor and a phosphorus-containing compound, mixing the solution with the mixture obtained in step 1), and then forming the mixture.

[0080] In the present invention, there is no particular limitation on the type of peptizing agent, and any peptizing agent conventionally defined in the art is applicable to the present invention. In some embodiments, the peptizing agent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid. Preferably, the amount of the peptizing agent is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4.

[0081] In the present invention, there is no particular limitation on the molding method in step 2), and those skilled in the art can select it according to actual needs, for example, it can be ball molding, tablet molding, extrusion molding, etc. For example, in a specific embodiment, extrusion molding is performed using an extruder.

[0082] In some embodiments, in step 2), the calcination conditions include: a temperature of 450-800°C for 1-15 hours; preferably, in step 2), the calcination conditions include: a temperature of 500-700°C for 1-12 hours. The calcination atmosphere is air or steam.

[0083] In some preferred embodiments, the method further comprises: 3) performing an activation treatment on the catalyst obtained in step 2) to obtain an activated catalyst. Preferably, the activation treatment is performed under an activating atmosphere, preferably a reducing atmosphere. Preferably, the activating atmosphere is selected from at least one of hydrogen, CO, ammonia, and hydrogen sulfide, more preferably hydrogen. Advantages of employing this preferred embodiment include higher hydrogen purity, easier control of the activation depth, and greater ease of implementation in industrial applications.

[0084] Preferably, in step 3), the activation treatment conditions include: temperature of 150-600°C, preferably 200-400°C; time of 0.5-30h, preferably 2-24h; flow rate of activation atmosphere of 0.001-100mL / min / g catalyst, preferably 0.01-50mL / min / g catalyst. The advantage of adopting such a preferred embodiment is that the activation treatment removes Cu in the catalyst. + / Cu 2+ Adjusting the ratio to a specific range (eg, 0.1-0.35) is beneficial to further significantly improve the stability and life of the catalyst.

[0085] In some preferred embodiments, step 2) further comprises: introducing a metal M component precursor and mixing it with the mixture obtained in step 1), a copper precursor and a phosphorus-containing compound. Preferably, the mass ratio of the metal M component precursor to the copper precursor is 1:50-1:1, preferably 1:25-1:2, calculated as elements. Preferably, the metal M component precursor is selected from at least one soluble compound of Group VIII metals and Group VIB metals, preferably selected from at least one soluble compound of Cr, Zn, Fe and Ni, more preferably selected from at least one of chromium chloride, chromium nitrate, zinc nitrate, zinc sulfate, nickel nitrate, nickel nitrate, basic nickel carbonate, nickel acetate, nickel sulfate, ferric nitrate, ferrous chloride and ferric chloride. The advantage of adopting such a preferred embodiment is that the metal M component cooperates with other modifying components (such as Cu) to increase the proportion of L acid and maintain Cu + / Cu 2+ When the ratio is within a specific range, the adsorption of the reaction raw materials with greater polarity on the acidic sites is reduced, the occurrence of side reactions is reduced, and the life of the catalyst is increased.

[0086] In the present invention, step 2) may further include hydrothermal treatment of the formed catalyst precursor prior to calcination. Preferably, in step 2), the hydrothermal treatment conditions include a temperature of 80-400°C, preferably 120-250°C, and a duration of 0.5-72 hours, preferably 8-48 hours. This preferred embodiment has the advantage of relatively mild conditions, ensuring that the catalyst skeleton structure is not destroyed, resulting in a catalyst with an excellent pore structure.

[0087] In the present invention, the "hydrothermal treatment" refers to a hydrothermal reaction in a broad sense: a reaction of the original mixture in a closed system, such as an autoclave, in the presence of an aqueous solvent or a non-aqueous solvent at a certain temperature and under the autogenous pressure of the solution. It will be understood that in the present invention, the hydrothermal reaction solution system depends on the type of the solvent and does not necessarily contain water. Preferably, the solvent is water. The present invention does not particularly limit the source of the solvent and can be provided by an external solvent or by the solvent of each reaction raw material precursor solution.

[0088] The method for preparing an N-alkylation catalyst provided by the present invention controls the order of adding raw materials during the catalyst preparation process, strictly follows the steps of first mixing the molecular sieve and the oxide binder, directly mixing them with a solution containing a copper precursor, a phosphorus-containing compound, and other components without calcination, and then forming the mixture. The mixture is then subjected to a single calcination and a preferred activation treatment to obtain the catalyst. Only one calcination is required during the catalyst preparation process, thus avoiding the multiple calcinations required for modification after catalyst formation in the prior art, reducing the acid loss caused by multiple calcinations, lowering the difficulty of the catalyst preparation process, and reducing energy consumption. Furthermore, the Cu in the catalyst is activated by the activation treatment.+ / Cu 2+ Adjusting the ratio to within a specific range is beneficial to further significantly improve the stability and life of the catalyst.

[0089] In a third aspect, the present invention also provides an N-alkylation catalyst obtained by the preparation method according to the second aspect.

[0090] In a fourth aspect, the present invention further provides use of the N-alkylation catalyst according to the first aspect or the N-alkylation catalyst obtained by the preparation method according to the second aspect in the N-alkylation reaction of aniline, particularly in the production of N,N-dimethylaniline by the N-alkylation reaction of aniline.

[0091] Production method of N,N-dimethylaniline

[0092] In a fifth aspect, the present invention provides a method for producing N,N-dimethylaniline, comprising reacting methanol and aniline in the presence of a catalyst to produce N,N-dimethylaniline, wherein the reaction is a gas phase reaction; wherein the catalyst is the N-alkylation catalyst according to the first aspect or the N-alkylation catalyst obtained by the preparation method according to the second aspect.

[0093] It should be noted that, in the present invention, the gas phase reaction means that the reaction raw materials methanol and aniline are fed in gaseous form or the reaction conditions during the reaction process are such that methanol and aniline are in gaseous state. The present invention does not particularly limit the gasification method of the raw materials, and all conventionally defined gasification methods in the art are applicable to the present invention.

[0094] In some embodiments, the molar ratio of methanol to aniline can be 1-10:1, preferably 2-8:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any two of the above values.

[0095] By using the N-alkylation catalyst according to the present invention, the applicable reaction temperature range can be broadened, so that a high conversion rate can be maintained at a reduced reaction temperature (e.g., as low as 230° C.). In some embodiments, the reaction temperature can be 180-350° C., preferably 220-300° C., for example, 180° C., 190° C., 200° C., 210° C., 220° C., 230° C., 240° C., 250° C., 260° C., 270° C., 280° C., 290° C., 300° C., 310° C., 320° C., 330° C., 340° C., 350° C., or within a range consisting of any two of the foregoing values.

[0096] In some embodiments, the mass space velocity of methanol and aniline is 0.1-10h-1 , preferably 0.5-4.5h -1 , for example 0.1h -1 , 0.5h -1 , 1h -1 , 2h -1 , 3h -1 , 4h -1 , 5h -1 , 6h -1 , 7h -1 , 8h -1 , 9h -1 , 10h -1 , or can be within a range consisting of any two of the above values.

[0097] In some embodiments, the method is carried out in at least one of a fixed bed reactor, a fluidized bed reactor, a moving bed reactor, and a slurry bed reactor, preferably in a fixed bed reactor.

[0098] The present invention provides a method for producing N,N-dimethylaniline. By employing a catalyst with high activity, high stability, extended life, and good recyclability, the method reduces side reactions, enables long-term stable operation of the N-alkylation reaction, and broadens the applicable reaction temperature, facilitating industrial continuous production. Furthermore, the method is environmentally friendly, with a recyclable catalyst and zero pollution and emissions during the production process.

[0099] This application also provides the following implementation scheme:

[0100] Scheme 1: A method for producing N,N-dimethylaniline, characterized in that methanol and aniline, as reaction materials, react in the presence of a catalyst, and the reaction is a gas-phase reaction;

[0101] Wherein, the preparation method of the catalyst comprises:

[0102] (1) mixing the molecular sieve and the carrier to obtain a mixture;

[0103] (2) The mixture obtained in step (1) is mixed with a solution containing a copper precursor and a phosphorus-containing compound to form a catalyst, and then calcined once to obtain a catalyst, wherein the amount of medium-strong acid in the catalyst accounts for more than 35% of the total acid amount.

[0104] Option 2: The method according to Option 1, wherein the amount of medium-strong acid in the catalyst accounts for 40-50% of the total acid amount, preferably 42-45%.

[0105] Scheme 3. The method according to Scheme 1 or 2, wherein in step (1), the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve and mordenite, preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve and β-type molecular sieve, and more preferably β-type molecular sieve;

[0106] Preferably, in step (1), the carrier is aluminum oxide and / or silicon oxide;

[0107] Preferably, in step (1), the mass ratio of the molecular sieve to the carrier calculated as oxide is 95:5-20:80, more preferably 90:10-25:75.

[0108] Scheme 4: The method according to Scheme 3, wherein, in step (1), the carrier exists in a solid state and / or a sol state, and more preferably exists in a sol state;

[0109] Preferably, in step (1), the carrier is alumina.

[0110] Scheme 5. The method according to any one of Schemes 1 to 4, wherein in step (2), the copper precursor is selected from soluble copper compounds, preferably at least one selected from cupric chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate;

[0111] Preferably, in step (2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, soluble phosphates and phosphites;

[0112] Preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate.

[0113] Scheme 6. The method according to any one of Schemes 1 to 5, wherein in step (2), the mass ratio of the copper precursor to the phosphorus-containing compound, calculated as elements, is 5:95-98:2, preferably 30:70-80:20;

[0114] Preferably, the mass ratio of the carrier calculated as oxide to the copper precursor calculated as element is 80:20-99.9:0.1, more preferably 85:15-99:1.

[0115] Scheme 7. The method according to Scheme 4, wherein the method for preparing the catalyst further comprises: introducing a peptizing agent into a solution containing a copper precursor and a phosphorus-containing compound and mixing the solution with the mixture obtained in step (1) to form a mixture;

[0116] Preferably, the peptizing agent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid and acetic acid;

[0117] Preferably, the amount of the peptizing agent used is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4.

[0118] Scheme 8. The method according to any one of schemes 1 to 7, wherein in step (2), the calcination conditions include: a temperature of 450-800° C. and a time of 1-15 h;

[0119] Preferably, in step (2), the calcination conditions include: temperature of 500-700° C. and time of 2-8 h.

[0120] Scheme 9. The method according to any one of Schemes 1-8, wherein the molar ratio of methanol to aniline is 1-10:1, preferably 2-8:1.

[0121] Scheme 10: The method according to any one of Schemes 1 to 9, wherein the reaction conditions include: a reaction temperature of 220-300°C, a mass space velocity of methanol and aniline of 0.1-10h - 1 ;

[0122] Preferably, the reaction conditions include: reaction temperature of 230-290°C, mass space velocity of methanol and aniline of 0.2-8h -1 .

[0123] Scheme 11. An alkylation catalyst, wherein the catalyst comprises Cu, a co-active component and a carrier; the co-active component is selected from at least one of Group VIII metals and Group VIB metals; the carrier comprises a molecular sieve and a binder; wherein the Cu in the catalyst + / Cu 2+ The ratio is 0.1-0.4.

[0124] Scheme 12. The catalyst according to Scheme 11, wherein the Cu + / Cu 2+ The ratio is 0.2-0.35;

[0125] and / or, the total pyridine infrared L-acidity of the catalyst accounts for more than 60% of the total pyridine infrared L-acidity, preferably 65-80%;

[0126] and / or, the catalyst contains mesopores and micropores;

[0127] Preferably, the mesopore volume of the catalyst accounts for 30-55% of the total pore volume, more preferably 40-50%.

[0128] Option 13. The catalyst according to Option 11 or 12, wherein the co-active component is selected from at least one of Cr, Zn, Fe and Ni, preferably selected from at least one of Cr, Zn and Ni;

[0129] Preferably, the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve and mordenite, more preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve and β-type molecular sieve, and even more preferably β-type molecular sieve;

[0130] Preferably, the binder is aluminum oxide and / or silicon oxide.

[0131] Scheme 14. The catalyst according to any one of Schemes 11-13, wherein, based on the total weight of the catalyst, the content of Cu in the catalyst as oxide is 0.5-20%, the content of the co-active component as oxide is 0.1-10%, the content of the molecular sieve is 20-92%, and the content of the binder as oxide is 6.9-78.9%.

[0132] Preferably, based on the total weight of the catalyst, the content of Cu in the catalyst as oxide is 1-18%, the content of the co-active component as oxide is 0.2-1%, the content of the molecular sieve is 60-80%, and the content of the binder as oxide is 7-35%.

[0133] Option 15. The catalyst according to Option 14, wherein the catalyst further contains an auxiliary agent;

[0134] Preferably, the auxiliary agent is selected from at least one of phosphorus, fluorine and boron;

[0135] Preferably, based on the total weight of the catalyst, the content of the additive in the catalyst as oxide is 0.5-12%, more preferably 0.8-9%.

[0136] Scheme 16. A method for preparing an alkylation catalyst, wherein the preparation method comprises the following steps:

[0137] (1) mixing the molecular sieve with the binder and then forming the mixture to obtain a carrier precursor;

[0138] (2) mixing a support precursor, a Cu precursor, and a co-active component precursor in the presence of a solvent, and then performing a hydrothermal treatment to obtain a catalyst precursor;

[0139] (3) calcining the catalyst precursor and then performing an activation treatment;

[0140] The co-activating component is selected from at least one of Group VIII metals and Group VIB metals.

[0141] Scheme 17. The method according to Scheme 16, wherein in step (1), the silicon-aluminum molar ratio of the molecular sieve is 3-1000;

[0142] Preferably, in step (1), the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve and mordenite, more preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve and β-type molecular sieve, and even more preferably β-type molecular sieve;

[0143] And / or, in step (1), the binder is aluminum oxide and / or silicon oxide;

[0144] Preferably, in step (1), the binder is provided in a solid and / or sol state.

[0145] Scheme 18. The method according to Scheme 16 or 17, wherein in step (2), the Cu precursor is selected from soluble compounds of Cu, preferably at least one selected from cupric chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate;

[0146] Preferably, in step (2), the co-active component is selected from at least one of Cr, Zn, Fe and Ni, and more preferably selected from at least one of Cr, Zn and Ni;

[0147] Preferably, in step (2), the co-active component precursor is selected from soluble compounds of the co-active components, and is further preferably selected from at least one of chromium chloride, chromium nitrate, zinc nitrate, zinc sulfate, nickel nitrate, nickel nitrate, basic nickel carbonate, nickel acetate, nickel sulfate, ferric nitrate, ferrous chloride and ferric chloride;

[0148] Preferably, in step (2), the conditions of the hydrothermal treatment include: temperature of 80-400°C and time of 0.5-72h;

[0149] Further preferably, in step (2), the conditions of the hydrothermal treatment include: temperature of 120-250° C., and time of 8-48 h.

[0150] Scheme 19. The method according to any one of Schemes 16 to 18, wherein the molecular sieve, binder, Cu precursor, and co-active component precursor are used in such amounts that, based on the total weight of the catalyst, the content of Cu as oxide is 0.5-20%, the content of the co-active component as oxide is 0.1-10%, the content of the molecular sieve is 20-92%, and the content of the binder as oxide is 6.9-78.9%.

[0151] Preferably, the amounts of the molecular sieve, binder, Cu precursor and co-active component precursor are such that, based on the total weight of the catalyst, the content of Cu in terms of oxide is 1-18%, the content of the co-active component in terms of oxide is 0.2-1%, the content of the molecular sieve is 60-80%, and the content of the binder in terms of oxide is 7-35%.

[0152] Option 20. The method according to Option 19, wherein step (2) further comprises: introducing an auxiliary agent precursor and mixing it with the carrier precursor, the Cu precursor and the co-active component precursor, and then performing a hydrothermal treatment to obtain a catalyst precursor;

[0153] Preferably, in step (2), the auxiliary agent is selected from at least one of phosphorus, fluorine and boron;

[0154] Preferably, the amount of the auxiliary agent precursor is such that, based on the total weight of the catalyst, the content of the auxiliary agent in the catalyst as oxide is 0.5-12%, more preferably 0.8-9%.

[0155] Scheme 21. The method according to any one of Schemes 16 to 20, wherein in step (3), the calcination conditions include: a temperature of 300-800° C. and a time of 0.5-24 h;

[0156] Preferably, in step (3), the activation treatment is carried out under an activation atmosphere, preferably the activation atmosphere is selected from at least one of hydrogen, CO, ammonia and hydrogen sulfide, more preferably hydrogen;

[0157] Preferably, in step (3), the activation treatment conditions include: a temperature of 150-600° C., a time of 0.5-30 h, and a flow rate of the activation atmosphere of 5-5000 mL / min relative to 1 g of catalyst precursor;

[0158] Further preferably, in step (3), the activation treatment conditions include: temperature of 200-400°C, time of 2-24h, and flow rate of activation atmosphere of 100-1200mL / min relative to 1g of catalyst precursor.

[0159] Scheme 22. An alkylation catalyst prepared by the preparation method described in any one of claims 16 to 21.

[0160] Use of the alkylation catalyst described in any one of Scheme 23, Schemes 11-15, and 22 in the N-alkylation reaction of aniline.

[0161] Scheme 24. A method for synthesizing N,N-dimethylaniline, wherein the synthesis method comprises: conducting an alkylation reaction of the reaction raw materials aniline and methanol in the presence of a catalyst, and the catalyst is the alkylation catalyst described in any one of Schemes 11-15 and 22.

[0162] Scheme 25. The synthesis method according to Scheme 24, wherein the reaction is a gas phase reaction;

[0163] Preferably, the conditions of the alkylation reaction include: a reaction temperature of 180-350°C, a mass space velocity of aniline and methanol of 0.01-5h -1 , the molar ratio of aniline to methanol is 1:1-20;

[0164] Further preferably, the conditions of the alkylation reaction include: reaction temperature of 190-300°C, mass space velocity of aniline and methanol of 0.5-4.5h -1 , the molar ratio of aniline to methanol is 1:1.5-18.

[0165] In order to facilitate the understanding of the present invention, the present invention lists the following embodiments, but the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0166] Example

[0167] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available. Among them, molecular sieves and oxide binder materials were purchased from Sinopec Catalyst Branch.

[0168] In the following Examples and Comparative Examples, aniline conversion and the selectivity distribution of the resulting products, N,N-dimethylaniline and N-methylaniline, were determined using an Anglient-7890 gas chromatograph equipped with a high-pressure injector (HP-PONA 50 m x 0.2 mm capillary column). The catalyst's single-pass life was determined by determining that the catalyst was deactivated when the aniline conversion dropped to 98%. The reaction time the catalyst experienced was defined as the catalyst's single-pass life.

[0169] In the following examples and comparative examples, the component contents of the catalysts, such as Al2O3, SiO2, CuO, P2O5, Cr2O3, ZnO, Fe2O3, NiO, etc., are calculated using X-ray fluorescence spectrometry analysis technology combined with the feed amount (see specific implementation method).

[0170] In the following examples and comparative examples, the acid distribution of the catalysts was measured using the NH3 temperature-programmed desorption method (NH3-TPD) (see the specific embodiment).

[0171] In the following examples and comparative examples, the pyridine infrared acid content of the catalyst was measured using a Bruker Tensor II Fourier transform infrared spectrometer (see the specific embodiment).

[0172] In the following examples and comparative examples, the Cu + / Cu 2+ The ratio was measured using the chemical adsorption module of the US Micromeritics ASAP 2460 adsorption instrument (see the specific embodiment).

[0173] Example 1

[0174] 1) Mix 90 g of HY molecular sieve (silicon-aluminum molar ratio n(SiO2):n(Al2O3) is 5, average particle size is 1 μm) and 10 g of alumina powder (average particle size is 20 μm);

[0175] 2) 3 g of cuprous chloride was added to 100 ml of a 10 wt% H₃PO₄ solution, and then added to the mixture from step 1). After mixing thoroughly, the mixture was extruded and calcined at 500°C for 12 hours to obtain Catalyst Y-1. X-ray fluorescence analysis revealed the following component contents: SiO₂: 71.39%, Al₂O₃: 23.22%, CuO: 2.00%, and P₂O₅: 3.39%. The acid content of Catalyst Y-1 is shown in Table 1.

[0176] In a fixed bed reactor, methanol and aniline were reacted using catalyst Y-1. The molar ratio of methanol to aniline was 3:1, and the mass space velocity of methanol and aniline was 1h -1 The reaction temperature was 250°C. The raw materials were pumped into the reactor using a raw material pump. Aniline and methanol were vaporized in the reactor and reacted after contacting the catalyst bed. The reaction results are shown in Table 2.

[0177] Example 2

[0178] 1) 750 g of β molecular sieve (silicon-aluminum molar ratio n(SiO2):n(Al2O3) of 20, average particle size of 1.5 μm) and 1250 ml of 20 wt% aluminum sol (average particle size of 10 nm) were mixed uniformly;

[0179] 2) 5 g of Cu2SO4 was added to 100 ml of a 15 wt% KH2PO4 solution. The solution was then added to the mixture from step 1) after adjusting the pH to 2.5 with nitric acid. After mixing thoroughly, the mixture was extruded and calcined at 600°C for 1 hour to obtain Catalyst β-1. X-ray fluorescence analysis revealed the following component contents: SiO2: 78.86%, Al2O3: 20.72%, CuO: 0.31%, and P2O5: 0.38%. The acid content of Catalyst β-1 is shown in Table 1.

[0180] The reaction was carried out using catalyst β-1 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0181] Example 3

[0182] 1) 200 g of ZSM-5 molecular sieve (silicon-aluminum molar ratio n(SiO2):n(Al2O3) is 50, average particle size is 0.5 μm) and 500 ml of 20 wt% silica sol (average particle size is 20 nm) are mixed uniformly;

[0183] 2) 10 g of Cu(NO₃)₂ was added to 250 ml of a 20 wt% K₃PO₄ solution, and the mixture was added to the mixture from step 1). After mixing thoroughly, the mixture was extruded and calcined at 800°C for 2 hours to obtain catalyst ZSM-1. X-ray fluorescence analysis revealed the following component contents: SiO₂: 94.41%, Al₂O₃: 1.24%, CuO: 2.05%, and P₂O₅: 2.28%. The acid content of catalyst ZSM-1 is shown in Table 1.

[0184] The reaction was carried out using catalyst ZSM-1 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0185] Example 4

[0186] A catalyst was prepared according to the method of Example 2, except that in step 2), 50 g of CuSO was added to 200 ml of a 25 wt% KHPO solution. The solution was then added to the mixture in step 1) after adjusting the pH to 4 with nitric acid and calcined at 500°C for 8 h to obtain Catalyst β-2. The component contents determined by X-ray fluorescence were: SiO: 74.09%, AlO: 19.47%, CuO: 2.88%, and PO: 3.55%. The acid content of Catalyst β-2 is shown in Table 1.

[0187] The reaction was carried out using catalyst β-2 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0188] Example 5

[0189] A catalyst was prepared according to the method of Example 2, except that in step 2), 60 g of CuSO was added to 500 ml of a 10 wt% KHPO solution, with all other conditions remaining unchanged, to obtain catalyst β-3. The component contents determined by X-ray fluorescence were: SiO: 73.68%, AlO: 19.36%, CuO: 3.44%, and PO: 3.53%. The acid content of catalyst β-3 is shown in Table 1.

[0190] The reaction was carried out using catalyst β-3 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0191] Example 6

[0192] A catalyst was prepared according to the method of Example 2, except that in step 2), 6 g of CuSO was added to 200 ml of a 25 wt% KHPO solution. All other conditions remained unchanged, yielding Catalyst β-4. The component contents determined by X-ray fluorescence were: SiO: 76.03%, AlO: 19.98%, CuO: 0.36%, and PO: 3.64%. The acid content of Catalyst β-4 is shown in Table 1.

[0193] The reaction was carried out using catalyst β-4 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0194] Example 7

[0195] A catalyst was prepared according to the method of Example 2, except that alumina powder (average particle size of 20 μm) was used instead of aluminum sol in step 1). Other conditions remained unchanged, to obtain Catalyst β-5. The component contents determined by X-ray fluorescence were substantially the same as those in Example 2. The acid content of Catalyst β-5 is shown in Table 1.

[0196] The reaction was carried out using catalyst β-5 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0197] Comparative Example 1

[0198] A catalyst was prepared according to the method of Example 1, except that a copper salt solution (100 ml of a 3 wt% CuCl solution) without phosphoric acid was added in step 2). All other conditions remained unchanged to obtain catalyst DY-1. X-ray fluorescence analysis revealed the following component contents: SiO₂: 73.90%, Al₂O₃: 24.03%, and CuO: 2.07%. The acid content of catalyst DY-1 is shown in Table 1.

[0199] The reaction was carried out using catalyst DY-1 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0200] Comparative Example 2

[0201] A catalyst was prepared according to the method of Example 1, except that a phosphoric acid solution containing no copper salt (100 ml of a 10 wt% H₃PO₄ solution) was added in step 2). All other conditions remained unchanged to obtain catalyst DY-2. X-ray fluorescence analysis revealed the following component contents: SiO₂: 72.85%, Al₂O₃: 23.69%, and P₂O₅: 3.46%. The acid content of catalyst DY-2 is shown in Table 1.

[0202] The reaction was carried out using catalyst DY-2 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0203] Comparative Example 3

[0204] A catalyst was prepared according to the method of Example 2, except that a phosphate-free copper salt solution (100 ml of a 5 wt% Cu2SO4 solution) was added in step 2). All other conditions remained unchanged to obtain catalyst Dβ-1. X-ray fluorescence analysis revealed the following component contents: SiO2: 78.95%, Al2O3: 20.74%, and CuO: 0.31%. The acid content of catalyst Dβ-1 is shown in Table 1.

[0205] The reaction was carried out using catalyst Dβ-1 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0206] Comparative Example 4

[0207] A catalyst was prepared according to the method of Example 2, except that a copper-free phosphate solution (100 ml of a 5 wt% KH2PO4 solution) was added in step 2). All other conditions remained unchanged, yielding catalyst Dβ-2. X-ray fluorescence analysis revealed the following component contents: SiO2: 78.89%, Al2O3: 20.73%, and P2O5: 0.38%. The acid content of catalyst Dβ-2 is shown in Table 1.

[0208] The reaction was carried out using catalyst Dβ-2 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0209] Comparative Example 5

[0210] A catalyst was prepared according to the method of Example 2, except that only β molecular sieve was added in step 1) and all other conditions remained unchanged, resulting in Catalyst Dβ-3. The component contents determined by X-ray fluorescence were: SiO2: 94.46%, Al2O3: 4.72%, CuO: 0.37%, and P2O5: 0.45%. The acid content of Catalyst Dβ-3 is shown in Table 1.

[0211] The reaction was carried out using catalyst Dβ-3 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0212] Comparative Example 6

[0213] A catalyst was prepared according to the method of Example 2, except that a mixture of 5 g of Cu2SO4 and 100 ml of a 15 wt% KH2PO4 solution was first used to soak the molecular sieves, followed by a primary calcination (600°C, 1 h), followed by a secondary calcination (650°C, 4 h) after mixing with alumina sol. The component contents determined by X-ray fluorescence were essentially the same as those of Example 2. The acid content of Catalyst Dβ-4 is shown in Table 1.

[0214] The reaction was carried out using catalyst Dβ-4 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0215] Comparative Example 7

[0216] A catalyst was prepared according to the method of Example 2, except that zinc sulfate solution (100 ml of a 15 wt% ZnSO solution) was used instead of the phosphate solution in step 2). All other conditions remained unchanged, yielding Catalyst Dβ-5. X-ray fluorescence analysis revealed the following component contents: SiO2: 78.45%, Al2O3: 20.61%, CuO: 0.31%, and ZnO: 0.63%. The acid content of Catalyst Dβ-5 is shown in Table 1.

[0217] The reaction was carried out using catalyst Dβ-5 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0218] Comparative Example 8

[0219] A catalyst was prepared according to the method of Example 2, except that ferric chloride was used instead of copper sulfate in step 2). All other conditions remained unchanged, resulting in catalyst Dβ-6. X-ray fluorescence analysis revealed the following component contents: SiO₂: 78.81%, Al₂O₃: 20.71%, Fe₂O₃: 0.11%, and P₂O₅: 0.38%. The acid content of catalyst Dβ-6 is shown in Table 1.

[0220] The reaction was carried out using catalyst Dβ-6 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0221] Comparative Example 9

[0222] A catalyst was prepared according to the method of Example 2, except that nickel nitrate was used instead of copper sulfate in step 2). All other conditions remained unchanged, resulting in catalyst Dβ-7. X-ray fluorescence analysis revealed the following component contents: SiO₂: 78.75%, Al₂O₃: 20.69%, NiO: 0.19%, and P₂O₅: 0.38%. The acid content of catalyst Dβ-7 is shown in Table 1.

[0223] The reaction was carried out using catalyst Dβ-7 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0224] Comparative Example 10

[0225] A catalyst was prepared according to the method of Example 2, except that zinc sulfate was used instead of copper sulfate in step 2). All other conditions remained unchanged, resulting in catalyst Dβ-8. X-ray fluorescence analysis revealed the following component contents: SiO₂: 78.73%, Al₂O₃: 20.69%, ZnO: 0.21%, and P₂O₅: 0.38%. The acid content of catalyst Dβ-8 is shown in Table 1.

[0226] The reaction was carried out using catalyst Dβ-8 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 2.

[0227] Table 1

[0228] From the results in Table 1 above, it can be seen that the catalyst obtained by using P and Cu to modify both the molecular sieve and the oxide binder according to the present invention shows an improved total acid content and a medium-strong acid content ratio compared to the comparative example catalysts obtained by using only P or Cu for modification, using P and Cu to modify a single molecular sieve, using P and Cu to modify a single molecular sieve and then calcining it once and then combining it with an oxide binder and calcining it twice, and using Zn and Cu for modification, using P and Fe for modification, using P and Ni for modification, and using P and Zn for modification, thereby effectively reducing the strong acid content ratio of the catalyst.

[0229] Table 2

[0230] From the results in Table 2 above, it can be seen that the catalyst obtained by combining P and Cu with the modified molecular sieve and the oxide binder according to the present invention can effectively reduce the selectivity of the main by-products N-methylaniline and N,N,C-trimethylaniline, and significantly improve the life of the catalyst.

[0231] Example 8

[0232] The catalyst was prepared according to the method of Example 2, except that after calcination, the temperature was lowered to 350°C and hydrogen (hydrogen flow rate was 10 mL / min / g catalyst) was introduced for activation for 2 hours to obtain catalyst β-6. The component contents determined by X-ray fluorescence spectrometry were basically the same as those in Example 2. The Cu content of catalyst β-6 was + / Cu 2+ The ratio and pyridine infrared acid content results are shown in Table 3.

[0233] The reaction was carried out using catalyst β-6 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 4.

[0234] Example 9

[0235] The catalyst was prepared according to the method of Example 8, except that in step 2), 100 g of Cu2SO4 and 12 g of zinc sulfate were added to 100 ml of a 20 wt% KH2PO4 solution, and other conditions remained unchanged to obtain catalyst β-7. The component contents determined by X-ray fluorescence spectrometry were: SiO2: 73.98%, Al2O3: 19.44%, CuO: 5.76%, P2O5: 0.35%, and ZnO: 0.48%. The Cu content of catalyst β-7 was 1.3747 W / v. + / Cu 2+ The results of the ratio and pyridine infrared acid content are shown in Table 3.

[0236] The reaction was carried out using catalyst β-7 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 4.

[0237] Example 10

[0238] The catalyst was prepared according to the method of Example 8, except that in step 2), 10 g of Cu2SO4 and 1.5 g of nickel nitrate were added to 100 ml of a 10 wt% K3PO4 solution, and other conditions remained unchanged to obtain catalyst β-8. The component contents determined by X-ray fluorescence spectrometry were: SiO2: 78.54%, Al2O3: 20.46%, CuO: 0.61%, P2O5: 0.16%, and NiO: 0.06%. The Cu content of catalyst β-8 was 78.54%, Al2O3: 20.46%, CuO: 0.61%, P2O5: 0.16%, and NiO: 0.06%. + / Cu 2+ The ratio and pyridine infrared acid content results are shown in Table 3.

[0239] The reaction was carried out using catalyst β-8 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 4.

[0240] Example 11

[0241] The catalyst was prepared according to the method of Example 8, except that in step 2), 100 g of Cu2SO4 and 12 g of ferrous chloride were added to 100 ml of a 10 wt% KH2PO4 solution, and other conditions remained unchanged to obtain catalyst β-9. The component contents determined by X-ray fluorescence spectrometry were: SiO2: 74.10%, Al2O3: 19.47%, CuO: 5.77%, P2O5: 0.35%, and Fe2O3: 0.30%. The Cu content of catalyst β-9 was 1.37%. + / Cu 2+ The ratio and pyridine infrared acid content results are shown in Table 3.

[0242] The reaction was carried out using catalyst β-9 according to the method and reaction conditions of Example 1. The reaction results are shown in Table 4.

[0243] Table 3

[0244] Table 4

[0245] It can be seen from the results in Tables 3 and 4 above that the catalyst according to the present invention can be + / Cu 2+ The ratio further significantly improves the activity and stability of the catalyst, especially significantly improves the life of the catalyst.

[0246] Example 12

[0247] The reaction was carried out using catalyst β-1 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0248] Example 13

[0249] The reaction was carried out using catalyst β-6 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0250] Example 14

[0251] The reaction was carried out using catalyst β-7 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0252] Example 15

[0253] The reaction was carried out using catalyst β-8 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0254] Example 16

[0255] The reaction was carried out using catalyst β-9 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0256] Comparative Example 11

[0257] The reaction was carried out using catalyst Dβ-1 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0258] Comparative Example 12

[0259] The reaction was carried out using catalyst Dβ-2 according to the method and reaction conditions of Example 1, except that the reaction temperature was 230°C. The reaction results are shown in Table 5.

[0260] Table 5

[0261] As can be seen from the results of Table 5 above, the conversion rate of raw material aniline in the process of synthesizing N,N-dimethylaniline at low temperature (230°C) using the catalyst of the present invention can still reach more than 99%, the catalyst life is longer than that at high temperature (250°C), the catalyst is more stable, side reactions are suppressed at low temperature (230°C), and the selectivity of N,N-dimethylaniline is higher. The catalyst provided by the present invention can be applied to synthesizing N,N-dimethylaniline at high temperature and at low temperature, thereby broadening the applicable reaction temperature range of the N-alkylation reaction and being conducive to realizing the long-term operation of the N,N-dimethylaniline production process.

[0262] Example 17

[0263] Catalyst β-1 was used in the reaction according to the method and reaction conditions of Example 1. After the aniline conversion dropped to 98% (the first cycle), the spent catalyst was recovered by gas-solid separation and regenerated for the next cycle. This was repeated four times. The results of the recycling performance evaluation are shown in Table 6.

[0264] Table 6 Recycling performance of catalyst β-1

[0265] From the results in Table 6 above, it can be seen that the catalytic performance and service life of the catalyst according to the present invention did not decrease significantly after four cycles, and the catalyst has good recycling performance and can be repeatedly used in the continuous production of N,N-dimethylaniline, which is beneficial to saving production costs.

[0266] The above describes in detail the specific embodiments of the present invention, 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 the contents disclosed by the present invention and fall within the scope of protection of the present invention.

Claims

1. An N-alkylation catalyst, characterized in that The catalyst comprises a molecular sieve, an oxide binder and a modifying component, wherein the modifying component is loaded on both the molecular sieve and the oxide binder, the modifying component comprises Cu and P, the percentage of the medium-strong acid content of the catalyst to the total acid content is not less than 35%, preferably not less than 40%, and more preferably not less than 42%, and the percentage of the medium-strong acid content to the total acid content is measured by the percentage of the desorption peak area at 250°C-450°C measured by the NH3 programmed temperature desorption method to the desorption peak area of ​​the total acid content.

2. The catalyst according to claim 1, characterized in that The molecular sieve is at least one of Y-type molecular sieve, ZSM-5 type molecular sieve, β-type molecular sieve, MCM-22 type molecular sieve and mordenite type molecular sieve, preferably at least one of Y-type molecular sieve, ZSM-5 type molecular sieve and β-type molecular sieve, more preferably β-type molecular sieve, and / or The oxide binder is aluminum oxide and / or silicon oxide.

3. The catalyst according to any one of the preceding claims, characterized in that The molar ratio of Cu:P in the catalyst, calculated as oxide, n(CuO):n(P2O5) is 30:1-1:25, preferably 20:1-1:10; and / or The mass ratio of the molecular sieve to the oxide binder is 95:5-20:80, preferably 90:10-25:

75.

4. The catalyst according to any one of the preceding claims, characterized in that The Cu in the catalyst + / Cu 2+ The ratio is 0-0.4, preferably 0.1-0.35; and / or, The pyridine infrared L acid content of the catalyst accounts for more than 60% of the total pyridine infrared acid content, preferably 65-80%.

5. The catalyst according to any one of the preceding claims, characterized in that The modifying component further comprises a metal M component selected from at least one of Group VIII metals and Group VIB metals; preferably, the metal M component is selected from at least one of Cr, Zn, Fe and Ni, more preferably selected from at least one of Cr, Zn and Ni.

6. A method for preparing an N-alkylation catalyst, characterized in that: The method comprises: 1) mixing a molecular sieve and an oxide binder to obtain a mixture; 2) The mixture obtained in step 1) is mixed with a solution containing a copper precursor and a phosphorus-containing compound, and then molded, and then calcined once to obtain a catalyst.

7. The preparation method according to claim 6, wherein: In step 1), the oxide binder is a solid oxide binder or a sol oxide binder, preferably a sol oxide binder; preferably, the concentration of the sol oxide binder is 0.1-50wt%, more preferably 10-30wt%; preferably, the pH of the sol oxide binder is 1-5; preferably, the average particle size of the sol oxide binder is 0.1-300nm; and / or, In step 1), the oxide binder is aluminum oxide and / or silicon oxide, more preferably aluminum sol and / or silica sol; and / or, In step 1), the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 molecular sieve, β-type molecular sieve, MCM-22 molecular sieve and mordenite, preferably at least one of Y-type molecular sieve, ZSM-5 molecular sieve and β-type molecular sieve, more preferably β-type molecular sieve; preferably, the silicon-aluminum molar ratio n(SiO2):n(Al2O3) of the molecular sieve is 2-1000:1, preferably 2-100:1; preferably, the average particle size of the molecular sieve is 0.01-50μm, preferably 0.1-20μm.

8. The preparation method according to any one of claims 6 to 7, wherein: In step 2), the copper precursor is selected from soluble copper compounds, preferably at least one selected from cupric chloride, cuprous chloride, cupric nitrate, cupric sulfate and cuprous sulfate; and / or, In step 2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, soluble phosphates and phosphites; preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate and diammonium dihydrogen phosphate.

9. The preparation method according to any one of claims 6 to 8, wherein: In step 2), the mass ratio of the copper precursor to the phosphorus-containing compound is 5:95-98:2, preferably 30:70-80:20, calculated as elements; and / or The mass ratio of the oxide binder to the copper precursor is 80:20-99.9:0.1, preferably 85:15-99:

1.

10. The preparation method according to any one of claims 6 to 9, wherein: In step (2), the calcination conditions include: temperature of 450-800°C, preferably 500-700°C; time of 1-15h, preferably 1-12h.

11. The preparation method according to any one of claims 6 to 10, wherein: When a sol-state oxide binder is used in step 1), the method further comprises: introducing a peptizing agent into a solution containing a copper precursor and a phosphorus-containing compound, mixing the mixture with the mixture obtained in step 1), and then forming the mixture; preferably, the peptizing agent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid and acetic acid; preferably, the amount of the peptizing agent is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4.

12. The preparation method according to any one of claims 6 to 11, wherein: The method further comprises: 3) performing an activation treatment on the catalyst obtained in step 2) to obtain an activated catalyst; Preferably, the activation treatment is carried out under an activation atmosphere, preferably the activation atmosphere is selected from at least one of hydrogen, CO, ammonia and hydrogen sulfide, more preferably hydrogen; Preferably, the activation treatment conditions include: temperature of 150-600°C, preferably 200-400°C; time of 0.5-30h, preferably 2-24h; flow rate of activation atmosphere of 0.001-100mL / min / g catalyst, preferably 0.01-50mL / min / g catalyst.

13. The preparation method according to any one of claims 6 to 12, wherein: Step (2) further comprises: introducing a metal M component precursor and mixing it with the mixture obtained in step 1), the copper precursor and the phosphorus-containing compound, Preferably, the mass ratio of the metal M component precursor to the copper precursor is 1:50-1:1, preferably 1:25-1:2, calculated on an element basis; Preferably, the metal M component precursor is selected from a soluble compound of at least one of Group VIII metals and Group VIB metals, preferably selected from a soluble compound of at least one of Cr, Zn, Fe and Ni, and more preferably selected from at least one of chromium chloride, chromium nitrate, zinc nitrate, zinc sulfate, nickel nitrate, nickel nitrate, basic nickel carbonate, nickel acetate, nickel sulfate, ferric nitrate, ferrous chloride and ferric chloride.

14. A method for producing N,N-dimethylaniline, characterized in that: The method comprises reacting methanol and aniline to generate N,N-dimethylaniline in the presence of a catalyst, wherein the reaction is a gas phase reaction; wherein the catalyst is the catalyst according to any one of claims 1 to 5 or a catalyst prepared by the method according to any one of claims 6 to 13.

15. The method according to claim 14, wherein: The reaction conditions include: a molar ratio of methanol to aniline of 1-10:1, preferably 2-8:1; a reaction temperature of 180-350°C, preferably 220-300°C; a mass space velocity of methanol and aniline of 0.1-10h -1 , preferably 0.5-4.5h -1 .

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