Ammonification catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts and discloses an ammonification catalyst as well as a preparation method and application thereof. The ammoniation catalyst provided by the invention has specific acidic central strength, acid content and pore structure, has higher catalytic performance on a reaction for preparing aromatic amine by phenol ammoniation, and can be used for synthesizing aromatic amine at a lower reaction temperature and a higher feed liquid phase airspeed at a higher conversion rate and selectivity.

Description

Technical Field

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

[0002] Aromatic amines are a class of widely used organic intermediates and products in industry. Products made from aromatic amines are widely used in synthetic materials, dyes, pesticides, rubber additives, medicine, and other fields.

[0003] The main production methods for aromatic amines include the nitroaromatic iron powder reduction method, the nitroaromatic catalytic hydrogenation method, the phenol amination method, and the halogenated aromatic amination method. Among these, the catalytic hydrogenation method and the phenol amination method are currently the main methods used in the industrial production of aromatic amines.

[0004] There are two main technical routes for the preparation of aromatic amines by phenol amination: solid acid catalysis and noble metal catalysis. Noble metal catalysis uses palladium-supported alumina catalysts, which are costly and have not yet been industrialized. Researchers have conducted extensive research on catalysts for solid acid catalysis in order to achieve industrial application. For example, US3272865A discloses a silica-alumina catalyst for the preparation of aromatic amines by phenol amination; however, the reaction conditions of this catalyst are harsh, with an aniline yield of 89% at 425℃ and 200 psig, and the catalyst deactivates after 40 hours. Japanese Patent Application Publication No. 1-164906 has achieved the industrial application of phenol amination technology, using a γ-Al₂O₃ catalyst with an ink bottle-like pore structure, achieving a phenol conversion and yield of up to 98%, but the operating temperature is still 380-400℃ and the space velocity is only 0.045 h⁻¹. -1 US5214210A discloses a high specific surface area ammoniation catalyst made from bayerite and pseudoboehmite, which can be used for the ammoniation reaction of monohydric phenols. The operating temperature is 365-390℃. Although the operating temperature is slightly lower than that of previous technologies, the ammonia / phenol ratio is 20:1 at 365℃, and the space velocity is only 0.04h⁻¹ under the condition of 98% phenol conversion. -1 .

[0005] It is evident that existing phenol amination catalysts still suffer from drawbacks such as high reaction temperature, low reaction space velocity, and large ammonia / phenol ratio, resulting in high energy consumption, large recycling volume, and reduced economic benefits. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of high energy consumption and insufficient production efficiency in the preparation of aromatic amines due to high reaction temperatures, low reaction space velocities, and large ammonia / phenol ratios in existing technologies. This invention provides an ammoniation catalyst, its preparation method, and its applications. The ammoniation catalyst provided by this invention can synthesize aromatic amines with high conversion rates and selectivity at relatively low reaction temperatures and high feed liquid hourly space velocities.

[0007] To achieve the above objectives, a first aspect of the present invention provides an ammoniation catalyst for catalyzing the synthesis of aromatic amines from phenols, the ammoniation catalyst comprising a main component and optional secondary components, wherein the main component is activated alumina;

[0008] When the ammoniation catalyst was measured by the NH3-TPD method, the maximum desorption peak was located at 230-250℃, the desorption acid content of the weak acid center was 90-140 μmol / g in the temperature range of 150-250℃, and the desorption acid content of the medium-strong acid center was 180-300 μmol / g in the temperature range of 250-550℃.

[0009] A second aspect of the present invention provides a method for preparing an ammoniation catalyst for catalyzing the synthesis of aromatic amines from phenols. The method includes modifying the catalyst with an acidic solution so that, when the ammoniation catalyst is measured by the NH3-TPD method, the maximum desorption peak is located at 230-250℃, the amount of desorbed weak acid centers is 90-140 μmol / g in the temperature range of 150-250℃, and the amount of desorbed medium-strong acid centers is 180-300 μmol / g in the temperature range of 250-550℃.

[0010] A third aspect of the present invention provides an ammoniation catalyst prepared according to the method described in the second aspect.

[0011] The fourth aspect of the present invention provides a method for preparing aromatic amines by amination of phenol, the method comprising contacting phenol with an amination agent in the presence of the amination catalyst described in the first or third aspect, and reacting under amination reaction conditions.

[0012] The fifth aspect of the present invention provides the use of the ammoniation catalyst described in the first or third aspect in reducing the temperature of the phenol ammoniation reaction and / or in increasing the liquid phase volume hour space velocity of the phenol ammoniation reaction.

[0013] Through the above technical solution, the present invention can achieve at least the following beneficial effects:

[0014] (1) The ammoniation catalyst provided by the present invention has a specific amount of acid and acid strength on its surface, thereby improving its catalytic activity and the selectivity of the target product.

[0015] (2) The ammoniation catalyst provided by the present invention can efficiently synthesize aromatic amines at a high liquid-phase feed space velocity under low reaction temperature and ammonia / phenol ratio conditions, which improves the safety and production efficiency of the reaction, reduces energy consumption, and is suitable for large-scale production and application.

[0016] (3) The preparation method of the ammoniation catalyst provided by the present invention is simple, the raw materials are readily available, and the obtained catalyst is a shaped catalyst that can be directly used in industrial production and has broad application prospects. Detailed Implementation

[0017] 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.

[0018] In this invention, the numbering of reagents, operations, etc. (e.g., "first" and "second" in "first drying" and "second drying") is only used to facilitate the differentiation of similar operations in different steps, and has no limiting effect on specific operation methods, conditions, or operation order.

[0019] The inventors of this invention discovered that the alumina catalyst used in the amination of phenols to prepare aromatic amines possesses a certain number of Bronsted acid sites (B acid sites) on its surface. The quantity and strength of these sites significantly influence the catalyst's ability to activate phenolic hydroxyl groups. Furthermore, the catalyst's composition, preparation, and treatment methods can all affect its surface and pore properties, resulting in different adsorption and diffusion properties of the reactants, thus manifesting macroscopic changes in catalytic activity. Extensive research by the inventors revealed that when the alumina catalyst used in the amination of phenols possesses specific surface properties, acid strength, and acid site content, it can achieve better catalytic performance under reaction conditions of lower reaction temperatures (e.g., room temperature) and higher feed liquid hourly space velocities.

[0020] Based on the above findings, the first aspect of the present invention provides an ammoniation catalyst for catalyzing the synthesis of aromatic amines from phenols, the ammoniation catalyst comprising a main component and optional secondary components, wherein the main component is activated alumina;

[0021] When the ammoniation catalyst was measured by the NH3-TPD method, the maximum desorption peak was located at 230-250℃, the desorption acid content of the weak acid center was 90-140 μmol / g in the temperature range of 150-250℃, and the desorption acid content of the medium-strong acid center was 180-300 μmol / g in the temperature range of 250-550℃.

[0022] In the catalyst provided by this invention, the "optional" component refers to a component that is not a necessary component in the catalyst. When the component is not present, the desired effect of this invention can be achieved as long as the catalyst meets the above requirements. When the above "optional" component is present in the catalyst, its performance can be further improved.

[0023] The catalyst provided by this invention uses Al2O3 as the main component. When its surface properties, acid strength and acid site content meet the above requirements, it can be regarded as the catalyst of this invention.

[0024] The NH3-TPD method, or "ammonia-programmed temperature desorption test," is commonly used to detect and analyze the acidity of catalyst surfaces. The NH3-TPD method can be performed using commercially available automated temperature-programmed desorption instruments; specific parameter settings can be found in the instrument manufacturer's instruction manual. The maximum desorption peak temperature determined by the NH3-TPD method represents the desorption temperature corresponding to the most abundant acidic sites on the catalyst surface, indicating the strength of the catalyst surface acidity; a higher desorption peak temperature indicates a stronger acidity. The amount of weak acid centers desorbed in the 150-250℃ temperature range represents the amount of weak acid on the catalyst surface that plays a catalytic role, mostly Brønsted (B) acids. The amount of moderately strong acid centers desorbed in the 250-550℃ temperature range is generally considered to represent the amount of moderately strong acid on the catalyst surface, including some stronger Brønsted (B) and Lewis (L) acids, which may promote the binding of reactants to the catalyst. "The amount of weak acid desorbed within the temperature range of 150-250℃ is 90-140 μmol / g" means that when the catalyst is tested by the NH3-TPD method, the amount of ammonia desorbed within the temperature range of 150-250℃ is 90-140 μmol / g; "The amount of medium-strong acid desorbed within the temperature range of 250-550℃ is 180-300 μmol / g" means that when the catalyst is tested by the NH3-TPD method, the amount of ammonia desorbed within the temperature range of 250-550℃ is 180-300 μmol / g.

[0025] For example, in the catalyst provided by the present invention, the amount of desorption weak acid center acid in the temperature range of 150-250℃ can be 90μmol / g, 95μmol / g, 100μmol / g, 105μmol / g, 110μmol / g, 115μmol / g, 120μmol / g, 125μmol / g, 130μmol / g, 135μmol / g, 140μmol / g, or it can be any range consisting of any two of the above values, or any intermediate value in the range.

[0026] For example, in the catalyst provided by the present invention, the amount of medium-strong acid core desorbed in the temperature range of 250-550℃ can be 180μmol / g, 190μmol / g, 200μmol / g, 210μmol / g, 220μmol / g, 230μmol / g, 240μmol / g, 250μmol / g, 260μmol / g, 270μmol / g, 280μmol / g, 290μmol / g, 300μmol / g, or it can be any range consisting of any two of the above values, or any intermediate value in the range.

[0027] According to a preferred embodiment of the present invention, the content of active alumina is not less than 90 wt.%, preferably not less than 95 wt.%, based on the total weight of the catalyst.

[0028] For example, based on the total weight of the catalyst, the content of active alumina in the catalyst can be 90 wt.%, 91 wt.%, 92 wt.%, 93 wt.%, 94 wt.%, 95 wt.%, 95.5 wt.%, 96 wt.%, 96.5 wt.%, 97 wt.%, 97.5 wt.%, 98 wt.%, 98.5 wt.%, 99 wt.%, 99.5 wt.%, 99.6 wt.%, 99.7 wt.%, 99.8 wt.%, 99.9 wt.%, or 100 wt.%, or a range consisting of any two of the above values, or any intermediate value within that range.

[0029] According to some preferred embodiments of the present invention, the optional subcomponent is selected from at least one of silicon oxide, titanium oxide, or zirconium oxide. Doping alumina with oxides of elements such as silicon, titanium, or zirconium can alter the number and intensity of bronsted acid sites in the catalyst, thereby further improving the catalyst activity.

[0030] Preferably, based on the total weight of the catalyst, the content of the sub-component can be 0-5 wt.%, more preferably 0.2-5 wt.%.

[0031] For example, based on the total weight of the catalyst, the content of the subcomponent can be 0, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2 wt.%, 2.2 wt.%, 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, 3 wt.%, 3.2 wt.%, 3.4 wt.%, 3.6 wt.%, 3.8 wt.%, 4 wt.%, 4.2 wt.%, 4.4 wt.%, 4.6 wt.%, 4.8 wt.%, 5 wt.%, or a range consisting of any two of the above values, or any intermediate value within that range.

[0032] The catalyst provided by this invention uses activated alumina as the main component. However, during the production of alumina or its raw materials, small amounts of alkali metals or their oxides may be introduced. During the preparation of the catalyst of this invention, these alkali metals or their oxides introduced from the activated alumina are not removed but are carried into the catalyst along with the main component. The inventors have discovered that the presence of alkali metal oxides in the catalyst provided by this invention can alter the strength and quantity of acidic sites on the catalyst, thereby affecting the catalyst activity. Therefore, the content of alkali metal oxides in the catalyst provided by this invention should be controlled within a certain level to obtain a catalyst with the expected reactivity.

[0033] According to a preferred embodiment of the present invention, the content of alkali metal oxides, based on the weight of the main component (i.e., alumina in the catalyst), does not exceed 1 wt.%, preferably 0-0.5 wt.%.

[0034] For example, based on the weight of the main component, the content of alkali metal oxides can be 0, 0.01 wt.%, 0.05 wt.%, 0.1 wt.%, 0.15 wt.%, 0.2 wt.%, 0.25 wt.%, 0.3 wt.%, 0.35 wt.%, 0.4 wt.%, 0.45 wt.%, 0.5 wt.%, or a range consisting of any two of the above values, or any intermediate value within that range.

[0035] The inventors of this invention have discovered that when the catalyst of this invention has pores of a specific size and type, the selectivity of the reaction for preparing aromatic amines using the catalyst can be effectively improved.

[0036] According to a preferred embodiment of the present invention, the catalyst has a pore type of cylindrical and / or ink bottle-shaped mesoporous structure. The pore type of the catalyst can generally be determined based on the morphology of the hysteresis loop in its adsorption-desorption isotherm diagram (refer to the H2 type curve among the six hysteresis loop types specified by IUPAC).

[0037] Preferably, the catalyst has mesopores of 2-50 nm in size.

[0038] According to a preferred embodiment of the present invention, the catalyst has a BET specific surface area of ​​150-300 m². 2 / g.

[0039] For example, the BET specific surface area of ​​the catalyst can be 150 m². 2 / g、160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g、200m 2 / g、210m 2 / g、220m 2 / g、230m 2 / g、240m 2 / g、250m 2 / g、260m 2 / g、270m 2 / g、280m 2 / g、290m 2 / g、300m 2 / g, or it can be any range of the two values ​​mentioned above, or any intermediate value within that range.

[0040] According to a preferred embodiment of the present invention, the average pore size of the catalyst by BJH desorption is 5-10 nm.

[0041] For example, the average pore size of the catalyst in the BJH desorption method can be 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, 9nm, 9.5nm, or 10nm, or it can be any range of any two of the above values, or any intermediate value in that range.

[0042] According to a preferred embodiment of the present invention, the pore size corresponding to 90% of the total pore volume, accumulated from the smallest pore, is 15-30 nm. Accumulating from the smallest pore means calculating the pore volume in ascending order of pore size, starting from a pore size of 2 nm, until the accumulated pore volume reaches 90% of the total pore volume of pores from 2-50 nm. The pore size corresponding to this point is the pore size corresponding to 90% of the total pore volume.

[0043] For example, starting from the smallest aperture, the aperture corresponding to a total aperture volume of 90% can be 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm, or 30nm, or it can be any range of any two of the above values, or any intermediate value within that range.

[0044] The inventors of this invention ingeniously discovered in their research that by modifying an ammoniation catalyst with alumina as the main component using an acidic solution, the content, strength, and amount of acidic sites on the catalyst surface can be effectively adjusted to give it the aforementioned characteristics, thereby obtaining a catalyst that meets the requirements of this invention.

[0045] Based on this, a second aspect of the present invention provides a method for preparing an ammoniation catalyst for catalyzing the synthesis of aromatic amines from phenols. The method includes modifying the catalyst with an acidic solution so that, when the ammoniation catalyst is measured by the NH3-TPD method, the maximum desorption peak is located at 230-250℃, the amount of desorbed weak acid centers is 90-140 μmol / g in the temperature range of 150-250℃, and the amount of desorbed medium-strong acid centers is 180-300 μmol / g in the temperature range of 250-550℃.

[0046] In industrial production, catalysts typically require molding to ensure they can be packed into industrial reactors and possess sufficient strength. The inventors of this invention have discovered that directly modifying a semi-finished molded catalyst as described above yields a molded catalyst that meets the aforementioned requirements. This approach is simpler and more suitable for large-scale applications. Furthermore, it avoids the problems of long research and development processes and high costs associated with the development of molded catalysts after laboratory catalyst development, which are often caused by differences between laboratory and industrial catalyst performance.

[0047] According to a preferred embodiment of the present invention, the method includes a step of modifying a molded catalyst semi-finished product with an acidic solution. "Molded catalyst semi-finished product" refers to a molded catalyst that has undergone molding but has not been modified. The process of modifying the molded catalyst semi-finished product with an acidic solution involves bringing the acidic solution into contact with the molded catalyst semi-finished product, causing its surface properties, the number of acidic sites, and acid strength to reach the aforementioned levels. Any modification method capable of achieving the above objectives is applicable to the present invention.

[0048] According to some preferred embodiments of the present invention, the step of modifying the molded catalyst semi-finished product includes: impregnating the molded catalyst semi-finished product with an acidic solution, and then sequentially subjecting the impregnated molded catalyst semi-finished product to a first drying and a first calcination.

[0049] Preferably, the impregnation conditions include: a temperature not exceeding 50°C and a time not exceeding 60 minutes.

[0050] More preferably, the impregnation conditions include: a temperature of 10-50°C (for example, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or any range of any two of the above values, or any intermediate value within that range), and a time of 10-60 min (for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any range of any two of the above values, or any intermediate value within that range).

[0051] The method provided by this invention can be used for the above-mentioned modification by impregnation with an equal volume of solution or by impregnation with an excess of solution. When using impregnation with an equal volume of solution, the amount of acidic solution can be adjusted according to the water absorption rate of the semi-finished catalyst. Preferably, the number of impregnations is one or more, and the specific number of impregnations can be adjusted according to the modification effect and the properties of the semi-finished catalyst itself.

[0052] According to a preferred embodiment of the present invention, the acidic solution comprises an aqueous solution of an acid modifier. The acid modifier may be any compound that is acidic in itself or whose aqueous solution is acidic, preferably selected from at least one of C1-C8 organic acids, inorganic acids, and inorganic acid salts.

[0053] Preferably, the acid modifier is selected from at least one of acetic acid, benzoic acid, sulfuric acid, boric acid, ammonium fluoride, ammonium chloride, and ammonium persulfate.

[0054] More preferably, the content of the acid modifier in the acidic solution can be 5-15 wt.%.

[0055] According to some preferred embodiments of the present invention, the first drying conditions are such that the moisture content in the impregnated shaped catalyst semi-finished product does not exceed 40 wt.%.

[0056] Preferably, the conditions for the first drying process include: a temperature of 70-150°C and a time of 2-8 hours.

[0057] According to some preferred embodiments of the present invention, the conditions for the first calcination include: a temperature not exceeding 500°C, preferably 250-480°C; a time of 2-8 hours; and preferably a heating rate of 80-150°C / hour for the first calcination.

[0058] For example, the temperature of the first roasting can be 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, or 480℃, or it can be a range consisting of any two of the above values, or any intermediate value in that range.

[0059] For example, the first roasting time can be 2h, 3h, 4h, 5h, 6h, 7h, or 8h, or it can be any range of two of the above values, or any intermediate value within that range.

[0060] For example, the heating rate of the first roasting can be 80℃ / h, 90℃ / h, 100℃ / h, 110℃ / h, 120℃ / h, 130℃ / h, 140℃ / h, 150℃ / h, or it can be a range consisting of any two of the above values, or any intermediate value in that range.

[0061] According to a preferred embodiment of the present invention, the method further includes the step of preparing a shaped catalyst semi-finished product.

[0062] Any preparation method used in the art for preparing shaped catalysts is applicable to this invention. According to some preferred embodiments of the invention, the step of preparing the shaped catalyst semi-finished product includes: kneading and shaping the shaped catalyst semi-finished product raw material sequentially in the presence of a solvent to obtain a shaped preform, and then subjecting the shaped preform to a second drying and a second calcination. "Shaped preform" refers to a blocky object with a desired shape formed from the kneaded shaped catalyst semi-finished product raw material by a certain method (e.g., extrusion, using a mold, etc.) before drying and calcination.

[0063] In this invention, there are no particular limitations on the specific shape of the shaped catalyst. Any shape used in the preparation of shaped catalysts in the art can be applied to this invention, as long as the shape, size, strength, etc., of the final shaped catalyst semi-finished product can meet the loading, unloading, and reaction requirements of the fixed-bed reactor. For example, it can be a regular shape such as spherical, near-spherical, strip-shaped, disc-shaped, or cubic, or an irregular shape such as clover-shaped, butterfly-shaped, or honeycomb-shaped. When a strip shape is used, its cross-section can be circular, rectangular, clover-shaped, etc., its length can be 2-5 mm, and the width at the widest point of the cross-section can be 2-5 mm; when a spherical or near-spherical shape is used, its diameter can be 2-5 mm. Preferably, the radial crushing strength of the shaped catalyst semi-finished product can be 50-150 N / piece.

[0064] Preferably, the raw materials for the shaped catalyst semi-finished product include an aluminum source, optional sub-component precursors, and optional auxiliary precursors.

[0065] Preferably, the aluminum source is selected from aluminum hydroxide (e.g., aluminum hydroxide gel, aluminum hydroxide gel, etc.) and / or boehmite. The aluminum source may contain small amounts of alkali metals and / or alkali metal oxides (usually Na and its oxides). To avoid adversely affecting the performance of the catalyst, the content of alkali metals and / or alkali metal oxides in the aluminum source is preferably such that, based on the weight of alumina, the content of alkali metal oxides in the prepared catalyst does not exceed 1 wt.%, preferably 0-0.5 wt.%.

[0066] Preferably, the optional subcomponent precursor is selected from at least one of amorphous silica-alumina, mordenite, metatitanic acid, zirconium oxynitrate, and zirconium oxysulfate.

[0067] Preferably, the amount of the semi-finished catalyst raw material used is such that, based on the total weight of the catalyst, the content of active alumina and secondary components in the obtained ammoniation catalyst meets the aforementioned requirements. Specific content details are not elaborated here.

[0068] To facilitate the preparation of the molded catalyst semi-finished product, the above method may further include additives commonly used in the preparation of molded catalysts in the art. For example, the molded catalyst semi-finished product raw material may also include a binder and / or an extrusion aid.

[0069] Preferably, the peptizing solvent can be at least one of citric acid, acetic acid, and nitric acid. The peptizing solvent can be provided in the form of an aqueous solution of the above compounds.

[0070] Preferably, the extrusion aid can be guar gum powder. The extrusion aid can be provided in the form of a guar gum powder suspension. Preferably, the guar gum powder content in the suspension is 3-10% by volume.

[0071] The present invention does not limit the specific amount of the above-mentioned auxiliary materials (such as adhesives, extrusion aids, etc.), and those skilled in the art can adjust them according to the molding condition of the semi-finished catalyst.

[0072] According to some preferred embodiments of the present invention, the second drying conditions are such that the moisture content in the molded preform does not exceed 5 wt.%. When the moisture content in the molded preform meets the above requirements, the crystal form of the active alumina in the obtained catalyst is more suitable, thereby making the activity of the phenol amination reaction better and possessing a certain mechanical strength, which is beneficial for its application in a reactor.

[0073] Preferably, the conditions for the second drying include: a temperature not exceeding 180°C, preferably 70-150°C; and a time of 2-8 hours.

[0074] Preferably, the conditions for the second calcination include: a temperature of not less than 500°C, preferably 500-1200°C; a time of 2-8 hours; and preferably a heating rate of 80-150°C / hour for the second calcination.

[0075] A third aspect of the present invention provides an ammoniation catalyst prepared according to the method described in the second aspect. The characteristics of this catalyst are as previously described and will not be repeated here.

[0076] The fourth aspect of the present invention provides a method for preparing aromatic amines by amination of phenol, the method comprising contacting phenol with an amination agent in the presence of the amination catalyst described in the first or third aspect, and reacting under amination reaction conditions.

[0077] According to a preferred embodiment of the present invention, the phenol is selected from at least one of monohydric phenols and polyhydric phenols (e.g., dihydric phenols, trihydric phenols, heterocyclic phenols, etc.), preferably at least one of phenol, cresol, and xylenol, and more preferably phenol. A monohydric phenol refers to a compound with one hydroxyl group directly connected to an aromatic ring; a polyhydric phenol refers to a compound with two or more hydroxyl groups directly connected to an aromatic ring; a heterocyclic phenol refers to a compound with one or more hydroxyl groups directly connected to an aromatic ring composed of a carbon atom and one or more atoms other than carbon.

[0078] In the method provided by this invention, phenol can be provided as a pure product (i.e., a pure phenolic compound or a mixture of several phenolic compounds) or in solution form. When provided in solution form, the solvent of the phenol solution is preferably a benzene compound, such as at least one of benzene, toluene, and xylene.

[0079] Preferably, the phenol content in the phenol solution is 30-70 wt.%.

[0080] According to a preferred embodiment of the present invention, the amination agent is selected from at least one of ammonia, primary amines (e.g., primary amines with 1-4 carbon atoms) and secondary amines (e.g., secondary amines with 1-4 carbon atoms), preferably ammonia.

[0081] Preferably, the amination agent is provided in liquid form. For example, it can be at least one of liquid ammonia, liquid primary amine, and liquid secondary amine.

[0082] Preferably, the amount of phenol and amination agent is such that the molar ratio of amination agent to phenol is 5-30:1, more preferably 10-20:1.

[0083] The ammoniation catalyst of the present invention can achieve its optimal catalytic performance under suitable process conditions. The phenol ammoniation reaction can be continuous or batch. Continuous operation refers to the preheating and mixing of components such as phenol, ammonifying agent, and inert carrier gas, followed by the reaction in a gas-phase fixed-bed reactor packed with the catalyst. Batch operation refers to the introduction of phenol, ammonifying agent, and catalyst into a reaction vessel, followed by thorough mixing and heating before the reaction. Preferably, the phenol ammoniation reaction is carried out continuously in a gas-phase fixed-bed reactor.

[0084] According to a preferred embodiment of the present invention, the ammoniation reaction conditions include: a temperature of 300-400°C; a pressure of 0.5-5 MPa; and a feed liquid hourly space velocity of 0.01-0.2 m / s. 3 / (m 3 ·h). m 3 / (m 3 •h) is the volume hourly space velocity (VHSV) of the liquid phase in the reaction feed, representing the velocity of a unit volume (m³) of liquid passing through the reactor per unit time (h). 3 The amount of liquid-phase feed of the catalyst (m) 3 ).

[0085] For example, the temperature of the ammoniation reaction can be 300℃, 305℃, 310℃, 315℃, 320℃, 325℃, 330℃, 335℃, 340℃, 345℃, 350℃, 355℃, 360℃, 365℃, 370℃, 375℃, 380℃, 385℃, 390℃, 395℃, or 400℃, or it can be a range consisting of any two of the above values, or any intermediate value within that range.

[0086] For example, the pressure of the ammoniation reaction can be 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, or 5 MPa, or it can be a range consisting of any two of the above values, or any intermediate value in that range.

[0087] For example, the feed liquid hourly space velocity for the ammoniation reaction can be 0.01 m. 3 / (m 3 ·h), 0.02m 3 / (m 3 ·h), 0.03m 3 / (m 3 ·h), 0.04m 3 / (m 3 ·h), 0.05m 3 / (m 3 ·h), 0.06m 3 / (m 3 ·h), 0.07m 3 / (m 3 ·h), 0.08m 3 / (m 3 ·h), 0.09m 3 / (m 3 ·h), 0.1m 3 / (m 3 ·h) 0.11m 3 / (m 3 ·h), 0.12m 3 / (m 3 ·h), 0.13m 3 / (m 3 ·h), 0.14m 3 / (m 3 ·h), 0.15m 3 / (m 3 ·h), 0.16m 3 / (m 3 ·h), 0.17m 3 / (m 3 ·h), 0.18m 3 / (m 3 ·h), 0.19m 3 / (m 3 ·h), 0.2m 3 / (m 3 ·h), or it can be any range of the two values ​​mentioned above, or any intermediate value in that range.

[0088] Preferably, the ammoniation reaction conditions include: temperature 360-380℃; pressure 1-3 MPa; and feed liquid hourly space velocity of 0.04-0.1 m / s. 3 / (m 3 ·h).

[0089] The fifth aspect of the present invention provides the use of the ammoniation catalyst described in the first or third aspect in reducing the temperature of the phenol ammoniation reaction and / or in increasing the liquid phase volume hour space velocity of the phenol ammoniation reaction.

[0090] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0091] Unless otherwise specified, all reagents and materials used in the following examples are commercially available products purchased from legitimate chemical reagent / material suppliers, and all reagents are of analytical grade.

[0092] Unless otherwise specified, the operating temperature in the following embodiments is room temperature (25±5℃).

[0093] Example 1

[0094] (1) Take 291.0g of alumina and 9.2g of amorphous silica-alumina and add them to guar gum powder and mix evenly. Then add 5 vol% nitric acid aqueous solution and knead in a kneader for 15 min. After kneading, extrude it into clover strips and cut it into particles about 4±1mm in length. Then dry it at 120℃ for 6 h (the water content after drying is 4.3%). After heating to 700℃ at a heating rate of 140℃ / h, calcine it at 700℃ for 8 hours to prepare catalyst molding semi-finished product 1.

[0095] (2) Dissolve 7.5g of ammonium fluoride in deionized water to make a 75mL solution. Take 100g of the above catalyst semi-finished product 2 and soak it evenly in the solution using the equal volume impregnation method. After absorption for 30 minutes, dry it at 120℃ for 4h (the water content after drying is 4%). Raise the temperature to 360℃ at a heating rate of 180℃ / h, and then calcine it at 360℃ for 4h to obtain the ammoniation catalyst ANL-1.

[0096] Example 2

[0097] (1) Take 290.3g of alumina and 8.9g of metatitanic acid, add them to guar gum powder and mix evenly. Then add 5 vol% nitric acid aqueous solution and knead in a kneader for 15 min. After kneading, extrude it into clover strips and cut it into particles about 4±1mm long. Dry it at 120℃ for 6 h (the water content after drying is 4%). Raise the temperature to 700℃ at a heating rate of 140℃ / h and calcine it at 700℃ for 8 hours to make catalyst molding semi-finished product 2.

[0098] (2) Dissolve 7.2g of glacial acetic acid in deionized water to make 72mL of solution. Take 100g of the above catalyst semi-finished product 1 and soak it evenly in the solution using the equal volume impregnation method. After absorbing at room temperature for 30 minutes, dry at 120℃ for 4h (the water content after drying is 3.9%). Raise the temperature to 360℃ at a heating rate of 180℃ / h, and then calcine at 360℃ for 4h to obtain the ammoniation catalyst ANL-2.

[0099] Example 3

[0100] (1) Take 290.6g of alumina and 9.0g of zirconium oxynitrate and add it to guar gum powder and mix evenly. Then add 5 vol% nitric acid aqueous solution and knead in a kneader for 15 min. After kneading, extrude it into clover strips and cut it into particles about 4±1mm in length. Then dry it at 120℃ for 6h (the water content after drying is 4.1%). After heating to 700℃ at a heating rate of 140℃ / h, calcine it at 700℃ for 8 hours to make catalyst molding semi-finished product 3.

[0101] (2) Dissolve 6.75g of sulfuric acid in deionized water to obtain a solution of 67.5mL. Take 100g of catalyst semi-finished product 3 and soak it evenly in the solution using the equal volume impregnation method. After absorption for 30 minutes, dry it at 120℃ for 4h (the water content after drying is 4%). Raise the temperature to 360℃ at a heating rate of 140℃ / h, and then calcine it at 360℃ for 4h to obtain the ammoniation catalyst ANL-3.

[0102] Example 4

[0103] The ammoniation catalyst was prepared according to the method in Example 1, except that:

[0104] (1) The calcination temperature in step (1) was adjusted to 500℃, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-1.

[0105] (2) The calcination temperature in step (1) was adjusted to 480℃, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-2.

[0106] (3) The drying temperature in step (1) was adjusted to 200℃, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-3;

[0107] (4) The heating rate in step (1) was adjusted to 180℃ / h, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-4.

[0108] (5) The calcination temperature in step (2) was adjusted to 520℃, and the other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-5.

[0109] (6) The drying temperature in step (2) was adjusted to 180°C, and the other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-6.

[0110] (7) The concentration of ammonium fluoride solution used in step (2) was increased to 20 wt%, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-7;

[0111] (8) The concentration of ammonium fluoride solution used in step (2) was reduced to 3 wt%, and other operations were the same as in Example 1, to obtain the ammoniation catalyst ANL-4-8.

[0112] (9) Replace the metatitanic acid in step (1) with an equal amount of alumina, and perform the other operations the same as in Example 1 to obtain the ammoniation catalyst ANL-4-9.

[0113] (10) Replace the metatitanic acid in step (1) with an equal amount of alumina, adjust the concentration of ammonium fluoride solution in step (2) to 5 wt%, and perform the other operations as in Example 1 to obtain the ammoniation catalyst ANL-4-10.

[0114] (11) Replace the metatitanic acid in step (1) with an equal amount of alumina, adjust the concentration of the acetic acid solution in step (2) to 3wt%, and perform the other operations as in Example 1 to obtain the ammoniation catalyst ANL-4-11.

[0115] (12) In step (1), sodium chloride was added before kneading to increase the sodium oxide content in the catalyst (based on the weight of alumina) to 1.13 wt.%. Other operations were the same as in Example 1, and the ammoniation catalyst ANL-4-12 was obtained.

[0116] Comparative Example 1

[0117] Take 100g of the catalyst semi-finished product 1 prepared in Example 1 and use it directly as an ammoniation catalyst, denoted as ammoniation catalyst ANL-0.

[0118] Test Example 1

[0119] This test example illustrates the characterization results of the composition, surface properties, and acidity of the ammoniation catalysts prepared in the above examples and comparative examples.

[0120] The elemental composition of the catalyst was determined by XRF and then converted into the content of the corresponding oxides in the catalyst.

[0121] The specific surface area and pore volume of the catalyst were determined using the BET method.

[0122] The acidic characteristics of the catalyst surface were detected using the NH3-TPD method.

[0123] For detailed test results, please refer to Table 1.

[0124] Table 1

[0125]

[0126]

[0127] Note: In Table 1, the contents of the main component and secondary component are weight percentages based on the total weight of the catalyst; the contents of alkali metal oxides are weight percentages based on the weight of the main component; pore size refers to the pore size corresponding to 90% of the total pore volume accumulated from the micropores; cumulative acid content refers to the total amount of NH3 desorbed by the NH3-TPD method; weak acid center acid content refers to the amount of NH3 desorbed at 150-250℃, and medium-strong acid center acid content refers to the amount of NH3 desorbed at 250-550℃.

[0128] Upon testing, the morphology of the hysteresis loops in the catalyst adsorption-desorption isotherms in Table 1 all conformed to the H2 type curve among the six types of hysteresis loops specified by IUPAC, indicating that they all have cylindrical and / or ink bottle-shaped mesopores.

[0129] Test Example 2

[0130] 150 mL of the ammoniation catalysts prepared in the examples and comparative examples were respectively loaded into a fixed-bed catalyst evaluation device. Ammonia was metered and preheated before being introduced into the reactor using a metering pump, and the system pressure was increased to 1.5 MPa. Then, a mixed solution of 50 wt% phenol and 50 wt% xylene was metered into the reactor. The three reacted through the catalyst bed under the following conditions: reaction temperature 370 °C; ammonia:phenol molar ratio of 16:1; and aniline liquid hourly space velocity of 0.05 h⁻¹. -1 After the reaction stabilized, samples were taken for analysis. The conversion rate and selectivity were calculated using the following method. The results are shown in Table 2.

[0131]

[0132] Table 2

[0133] Catalyst number Phenol conversion rate (%) Aniline selectivity (%) Diphenylamine selectivity (%) ANL-1 97.98 99.00 0.69 ANL-2 69.11 99.21 0.24 ANL-3 89.44 99.21 0.21 ANL-4-1 95.40 98.96 0.66 ANL-4-2 92.66 98.85 0.66 ANL-4-3 93.51 98.94 0.58 ANL-4-4 91.47 98.98 0.59 ANL-4-5 91.22 98.69 0.81 ANL-4-6 94.58 98.81 0.67 ANL-4-7 95.81 98.90 0.65 ANL-4-8 96.66 98.80 0.70 ANL-4-9 97.39 98.93 0.72 ANL-4-10 97.45 98.93 0.72 ANL-4-11 93.51 99.07 0.52 ANL-4-12 92.08 98.74 0.82 ANL-0 54.80 99.01 0.20

[0134] As can be seen from the evaluation data of each catalyst in Table 2, the modified amination catalysts prepared in Examples 1-3 of this invention exhibit excellent phenol conversion and aniline selectivity. Compared with the comparative examples, all catalysts in the examples show a significant improvement in the catalytic effect of the reaction of phenol to aromatic amine.

[0135] Test Example 3

[0136] 150 mL of the ammoniation catalyst ANL-2 prepared in Example 2 was measured and loaded into a fixed-bed evaluation device. The effects of different reaction conditions on the performance of the ammonolysis catalyst were investigated by varying only the reaction conditions, such as temperature, pressure, the molar ratio of ammonia to phenol, and the liquid hourly space velocity of phenol. The reaction products were detected and calculated using the method described in Test Example 2. The specific conditions and results are shown in Table 3.

[0137] Table 3

[0138]

[0139] As can be seen from the evaluation data in Table 3, within the range of process conditions, the ammoniation catalyst prepared in this invention has excellent catalytic effect on the reaction of phenol to aromatic amine.

[0140] Test Example 4

[0141] 150 mL of the amination catalyst ANL-2 prepared in Example 2 was measured and loaded into a fixed-bed reactor. Ammonia, after preheating, was metered into the reactor using a metering pump, and the system pressure was increased to 1.5 MPa. Then, a mixed solution of 50 wt% phenol and 50 wt% xylene was metered into the reactor. The three reacted through the catalyst bed under the following conditions: reaction temperature 370 °C; ammonia:phenol molar ratio 16:1; and aniline liquid hourly space velocity (LHSV) 0.05 h⁻¹. -1 The stability of the ammoniation catalyst was investigated through this continuous evaluation test, and the specific results are shown in Table 4.

[0142] Table 4

[0143]

[0146] As can be seen from the data in Table 4, the ammoniation catalyst prepared in this invention did not show significant attenuation in activity and selectivity within the evaluation time range, and has good stability.

[0147] As can be seen from the above experimental examples, the ammoniation catalyst prepared by the present invention can catalyze the reaction of phenol to aromatic amine at a relatively low temperature and ammonia / phenol ratio with a relatively high space velocity.

[0148] 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. An amination catalyst for catalyzing the synthesis of aromatic amines from phenols, characterized in that, The ammoniation catalyst comprises a main component and optional secondary components, wherein the main component is activated alumina; When the ammoniation catalyst was measured by the NH3-TPD method, the maximum desorption peak was located at 230-250℃, the desorption acid content of the weak acid center was 90-140 μmol / g in the temperature range of 150-250℃, and the desorption acid content of the medium-strong acid center was 180-300 μmol / g in the temperature range of 250-550℃.

2. The ammoniation catalyst according to claim 1, wherein, Based on the total weight of the catalyst, the content of active alumina shall not be less than 90 wt.%, preferably not less than 95 wt.%; Preferably, the optional sub-component is selected from at least one of silicon oxide, titanium oxide, or zirconium oxide; More preferably, the content of the sub-component is 0-5 wt.%, preferably 0.2-5 wt.%, based on the total weight of the catalyst.

3. The ammoniation catalyst according to claim 1 or 2, wherein, The catalyst has a BET specific surface area of ​​150-300 m². 2 / g; And / or, the average pore size of the catalyst by BJH desorption is 5-10 nm; And / or, starting from the smallest aperture, the pore size corresponding to a total pore volume of 90% is 15-30 nm.

4. A method for preparing an ammoniation catalyst for catalyzing the synthesis of aromatic amines from phenols, characterized in that, The method includes modifying the catalyst with an acidic solution so that, when the aminated catalyst is measured by the NH3-TPD method, the maximum desorption peak is located at 230-250℃, the amount of desorbed weak acid centers is 90-140 μmol / g in the temperature range of 150-250℃, and the amount of desorbed medium-strong acid centers is 180-300 μmol / g in the temperature range of 250-550℃.

5. The method according to claim 4, wherein, The method includes the step of modifying the semi-finished catalyst product with an acidic solution; Preferably, the step of modifying the molded catalyst semi-finished product includes: impregnating the molded catalyst semi-finished product with an acidic solution, and then sequentially subjecting the impregnated molded catalyst semi-finished product to a first drying and a first calcination. More preferably, the impregnation conditions include: a temperature not exceeding 50°C and a time not exceeding 60 minutes; Preferably, the acidic solution comprises an aqueous solution of an acid modifier, wherein the acid modifier is preferably selected from at least one of C1-C8 organic acids, inorganic acids, and inorganic acid salts; More preferably, the acid modifier is selected from at least one of acetic acid, benzoic acid, sulfuric acid, boric acid, ammonium fluoride, ammonium chloride, and ammonium persulfate; More preferably, the content of the acid modifier in the acidic solution is 0.1-20 wt.%, preferably 5-15 wt.%. More preferably, the first drying conditions are such that the moisture content in the impregnated molded catalyst semi-finished product does not exceed 40 wt.%, and the preferred first drying conditions include: temperature 70-150°C, time 2-8 h; More preferably, the conditions for the first calcination include: a temperature not exceeding 500°C, preferably 250-480°C; a time of 2-8 hours; and preferably a heating rate of 80-150°C / hour for the first calcination.

6. The method according to claim 4 or 5, wherein, The method further includes the step of preparing a shaped catalyst semi-finished product; Preferably, the step of preparing the shaped catalyst semi-finished product includes: kneading and shaping the shaped catalyst semi-finished product raw material in the presence of a solvent to obtain a shaped preform, and then subjecting the shaped preform to a second drying and a second calcination in sequence. Preferably, the shaped catalyst semi-finished product raw material includes an aluminum source, optional secondary component precursors and optional auxiliary agent precursors. More preferably, the solvent is selected from aqueous solutions of inorganic acids, preferably aqueous solutions of at least one of nitric acid, sulfuric acid and HCl; More preferably, the aluminum source is selected from aluminum hydroxide and / or boehmite; More preferably, the optional subcomponent precursor is selected from at least one of amorphous silica-alumina, mordenite, metatitanic acid, zirconium oxynitrate, and zirconium oxysulfate. More preferably, the amount of the semi-finished raw material for the shaped catalyst is such that, based on the total weight of the catalyst, the content of active alumina in the obtained ammoniation catalyst is not less than 90 wt.%; the content of secondary components is 0-5 wt.%; and the content of alkali metal oxides is 0-1 wt.%. More preferably, the raw material for the molding catalyst semi-finished product further includes a peptizing solvent and / or an extrusion aid; More preferably, the second drying conditions ensure that the moisture content in the molded preform does not exceed 5 wt.%, and the preferred second drying conditions include: a temperature not exceeding 180°C, preferably 70-150°C; and a time of 2-8 hours. More preferably, the conditions for the second calcination include: a temperature of not less than 500°C, preferably 500-1200°C; a time of 2-8 hours; and preferably a heating rate of 80-150°C / hour for the second calcination.

7. The ammoniation catalyst prepared by the method according to any one of claims 4-6.

8. A method for preparing aromatic amines by phenol amination, characterized in that, The method comprises contacting a phenol with an amination agent in the presence of an amination catalyst as described in any one of claims 1-4 and 7, and reacting the phenol under amination reaction conditions.

9. The method according to claim 8, wherein, The phenol is selected from at least one of monohydric phenols and polyhydric phenols, preferably at least one of phenol, cresol and hydroquinone, and more preferably phenol; And / or, the amination agent is selected from at least one of ammonia, primary amines and secondary amines, preferably ammonia; Preferably, the amount of phenol and amination agent is such that the molar ratio of amination agent to phenol is 5-30:1, more preferably 10-20:1; And / or, the ammoniation reaction conditions include: a temperature of 300-400℃, preferably 360-380℃; a pressure of 0.5-5MPa, preferably 1-3MPa; and a feed liquid hourly space velocity of 0.01-0.2 m / s. 3 / (m 3 •h), preferably 0.04-0.1m 3 / (m 3 ·h).

10. The use of the ammoniation catalyst according to any one of claims 1-4 and 7 in reducing the temperature of the phenol ammoniation reaction and / or in increasing the liquid phase space velocity of the phenol ammoniation reaction.

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