A solid acid-base catalyst for preparing salicylonitrile, its preparation method and application

Abstract

The application discloses a solid acid-base catalyst for preparing salicylonitrile, a preparation method of the solid acid-base catalyst and a method for preparing salicylonitrile by using the catalyst. The solid acid-base catalyst comprises a basic component, an acidic component and an additive; the basic component is at least one selected from active MgO, CaO and La2O3, the acidic component is at least one selected from SiO2, Al2O3 or a molecular sieve, and the additive is at least one selected from ZnO and a C component. According to the preparation method of the application, the specific solid acid-base catalyst is adopted to directly prepare salicylonitrile from phenol and urea. The salicylonitrile prepared by the method can effectively reduce the production cost, improve the production safety, reduce the three-waste discharge amount in the preparation of salicylonitrile by using the existing process, and improve the product quality. The method is a sustainable and green synthesis route.

Description

Technical fields:

[0001] This application belongs to the field of pharmaceutical and chemical intermediates and related chemical technologies. Specifically, it relates to a solid acid-base catalyst for preparing salicylates, a method for preparing the same, and a method for preparing salicylates using the catalyst. Background technology:

[0002] 2-Cyanophenol (also known as o-hydroxybenzonitrile, 2-cyanophenol) Salicylic acid nitrile is a grayish-white powdery solid with a melting point of 92℃-95℃ and a boiling point of 149℃ / 14mmHg. It has a bitter and highly irritating odor. Salicylic acid nitrile is an important intermediate for the antihypertensive drug brenilol, the fungicide pyraclostrobin, and can also be used as a liquid crystal material and fragrance.

[0003] The preparation methods of salicylnitrile mainly include the salicylaldehyde oxime dehydration method (US5637750, CN201010106946) using salicylaldehyde and hydroxylamine hydrochloride as raw materials, and the direct dehydration method using salicylamide as raw material. The salicylaldehyde oxime dehydration method is cumbersome to operate, has high raw material costs, low salicylnitrile yield, and generates a large amount of industrial waste. The salicylamide dehydration method typically uses dehydrating agents such as phosphorus oxychloride, phosphorus pentasulfide, thionyl chloride (CN111848443A), phosgene (CN105152972A, CN106083648A), and triphosgene (CN102516122 A). The use of phosphorus oxychloride, phosphorus pentasulfide, and thionyl chloride generates large amounts of phosphorus- and sulfur-containing wastewater during production, which is highly detrimental to industrial production in today's increasingly stringent environmental protection requirements. Using phosgene as a dehydrating agent offers advantages such as high selectivity, few byproducts, and high yield. However, phosgene is highly toxic and generally exists in gaseous form at room temperature, posing a threat to human life should a leak occur. In comparison, triphosgene exists in solid form at room temperature, making it safer to use. However, triphosgene is more expensive, still possesses certain corrosiveness and toxicity, and requires strict control over production equipment and operations. Furthermore, the reaction may generate phosgene, necessitating careful treatment of phosgene tail gas and wastewater. In recent years, researchers have explored heterogeneous solid catalysts to promote the dehydration reaction of salicylamide, such as vanadium oxide (CN108863849), phospholipid silica gel (US6248917), and SO4. 2- / Zr(SO4) 2 Using montmorillonite (CN109433230A) as a catalyst significantly reduces waste, but the high-temperature reaction consumes a lot of energy, resulting in a higher overall production cost.

[0004] Considering the high price of salicylamide, researchers have attempted to prepare salicylate using salicylic acid as a raw material. Li Wenqing et al. (Guangdong Chemical Industry, 2011, 38(5):87-88; CN102174002A) reacted salicylic acid with ammonia to generate ammonium salicylate, which was then reacted with urea, aminosulfonic acid and alkaline catalyst in a one-pot high-temperature process to generate salicylate, with a yield of over 86%. However, this method has a long process flow, is relatively cumbersome, consumes a large amount of urea and aminosulfonic acid, and the catalyst cannot be reused, which limits its industrial application. Based on this, Zhao Jingrui et al. (CN106431981A) directly used salicylic acid, urea and aminosulfonic acid as basic raw materials, and methyl benzoate as solvent. Under the action of a mixture of magnesium oxide and cyanuric chloride catalyst, salicylic acid was converted into salicylate in one step. The product purity can reach about 95%, and the yield can reach 80%, which reduces the amount of urea and aminosulfonic acid used and simplifies the process flow. However, the large amount of solvent methyl benzoate used and the subsequent vacuum distillation recovery result in low production efficiency.

[0005] In addition, there are also reports on the preparation of salicylnitrile from methyl salicylate. CN102304061 A reported a method of reacting methyl salicylate and ammonia in toluene as a solvent to produce salicylamide, then heating to recover toluene and the reaction byproduct methanol, and cooling the remaining material to 20-25℃, crystallizing and centrifuging to obtain salicylamide raw material. Chen Guanhu et al. (Modern Chemical Industry, 2020, 40(3):143-147) catalyzed the direct reaction of methyl salicylate and ammonia in a fixed-bed reactor with AlPO4 solid acid catalyst to produce salicylnitrile, at a temperature of 480℃ and a methyl salicylate space velocity of 0.3h. -1 When the molar ratio of ammonia to methyl salicylate is 14:1, the conversion rate of salicylic acid is 98.8%, the selectivity of salicylate is 87.1%, and the total yield is about 86.1%. Chen Erzhong et al. (Pesticides, 2018, 57(12):870-872, CN 104549378 A) used a self-made solid catalyst SYR-05 to synthesize salicylate in one step by catalytic nitrification of methyl salicylate through a gas-solid phase fixed bed process. The yield can reach more than 90%, and the catalyst can be continuously operated for more than 200 hours.

[0006] Fixed-bed synthesis simplifies the process and facilitates continuous production, but it places high demands on the catalyst, generates significant exothermic reactions, and slow heat transfer can lead to catalyst sintering. Compared to fixed-bed synthesis, fluidized-bed synthesis offers better mass and heat transfer, effectively preventing runaway reactions caused by excessive exothermic reactions during the ammonia nitridation of salicylic acid / methyl salicylate, thus protecting the catalyst. Wang Jingli et al. (CN110698362A) activated the catalyst by loading it into a two-stage fluidized bed and heating it. Liquid hydrated methyl salicylate and ammonia were then simultaneously injected into the gasification chamber for vaporization. The mixed gas underwent catalytic reaction in the fluidized bed and liquefied before entering a receiving tank to obtain salicylonitrile liquid. Part of the tail gas was recycled back to the fluidized bed, while the remainder was absorbed by sulfuric acid and then treated as tail gas. The conversion rate reached 98%, and the selectivity reached 96%. However, the price of the raw material methyl salicylate remains high, and special attention must be paid to safety during the transportation, storage, and use of ammonia.

[0007] The tightening of safety policies in chemical production and the increasing demands for environmental protection have posed significant challenges to the synthesis of salicylnitrile. Traditional salicylnitrile synthesis processes are cumbersome and generate substantial amounts of waste, making them unsuitable for modern applications. One-step and continuous processes have become important directions for the development of salicylnitrile synthesis. To address the problems with existing technologies, it remains necessary to develop new, more economical, and environmentally friendly process routes for the preparation of salicylnitrile. Summary of the Invention:

[0008] To address the shortcomings of the existing technology, the purpose of this application is to provide a solid acid-base catalyst for preparing salicylanilide, a method for preparing the same, and a method for preparing salicylanilide using the solid acid-base catalyst. The method for preparing salicylanilide involves reacting phenol and urea in one step using the solid acid-base catalyst according to the present invention to generate salicylanilide. The resulting product is then filtered or centrifuged, washed with water, pulped, and crystallized or recrystallized to obtain salicylanilide with high purity. This method effectively reduces production costs, improves production safety, reduces the amount of waste generated during the preparation of salicylanilide using existing processes, and improves product quality.

[0009] According to one aspect of the present invention, an object of the present invention is to provide a solid acid-base catalyst for the preparation of salicylates, the solid acid-base catalyst comprising a basic component, an acidic component, and an auxiliary agent; wherein the basic component is at least one selected from active MgO, CaO, and La2O3, the acidic component is at least one selected from SiO2, Al2O3, or molecular sieves, and the auxiliary agent is at least one selected from ZnO and C components. Based on 100 parts by weight of the solid acid-base catalyst, the basic component is 40 to 80 parts by weight, the acidic component is 10 to 40 parts by weight, and the auxiliary agent is 5 to 20 parts by weight.

[0010] Preferably, the molecular sieve is at least one selected from Hβ, ZSM-5, SAPO-34, HY and their acid-modified molecular sieves, and preferably ZSM-5.

[0011] Preferably, the C component is at least one selected from activated carbon, carbon black, and carbon components obtained by pyrolysis of organic carbon compounds, and is preferably activated carbon.

[0012] Preferably, based on 100 parts by weight of the solid acid-base catalyst, the alkaline component is 40-70 parts by weight, the acidic component is 20-40 parts by weight, and the auxiliary agent is 5-15 parts by weight.

[0013] More preferably, based on 100 parts by weight of the solid acid-base catalyst, the alkaline component is 40 to 60 parts by weight, the acidic component is 20 to 40 parts by weight, and the auxiliary agent is 5 to 10 parts by weight.

[0014] The acid-modified molecular sieve is obtained by modifying the molecular sieve in an aqueous solution of an organic or inorganic acid. The organic acid is one of citric acid, tartaric acid, or acetic acid, and the inorganic acid is one of hydrochloric acid, nitric acid, or phosphoric acid. The concentration of the aqueous solution of the organic or inorganic acid is 0.05-0.5 mol / L.

[0015] This invention also provides a method for preparing acid-modified molecular sieves, the method comprising the following steps:

[0016] 1) Add a molecular sieve selected from Hβ, ZSM-5, SAPO-34 or HY to an aqueous solution of organic or inorganic acid;

[0017] 2) Stir at room temperature for 5-48 hours, then filter and wash until neutral. Place in a drying oven at 120℃ for 12 hours.

[0018] The ratio of molecular sieve to aqueous solution of organic or inorganic acid is 1g:8mL~15mL.

[0019] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing the solid acid-base catalyst for preparing salicylates, the method comprising the following steps: mixing 40-70 parts by weight (based on oxides) of one or a mixture of Mg salt, Ca salt, La salt, 20-40 parts by weight (based on oxides) of aluminum sol or silica sol or molecular sieve powder, 5-15 parts by weight of Zn salt (based on oxides) or C powder, an appropriate amount of water and a binder to form a slurry, stirring it evenly in a stirrer, spraying it into solid microspheres through a spray dryer, drying the microspheres at 100°C, and then calcining them in an inert gas atmosphere at 500°C-700°C to obtain the solid acid-base catalyst.

[0020] The adhesive is guar gum and / or PEG.

[0021] Alternatively, the solid acid-base catalyst of the present invention can also be prepared by the following other methods: dispersing at least one of the basic components, such as oxide powders of MgO, CaO, and La2O3, at least one of the acid components, such as SiO2, Al2O3, or molecular sieve powder, and at least one of the auxiliary components, such as ZnO and C powder, in water; heating and stirring at 25°C to 100°C for 5 to 12 hours; then evaporating the water to obtain a mixture; molding the mixture; drying it at 100°C; and then calcining it in an inert gas atmosphere at 500°C to 700°C to obtain the solid acid-base catalyst.

[0022] Furthermore, the molding process involves adding water and a binder to the dried mixture, grinding and mixing, and then extruding the mixture into strips, wherein the binder is guar gum and / or PEG.

[0023] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing salicylnitrile, the method being shown in reaction formula 1 below, comprising the following steps:

[0024]

[0025] Phenol and urea, in solid, molten, or solution form, are fed into a continuous reactor with fluidized bed gas. The reactor is filled with the solid acid-base catalyst described according to the present invention, allowing phenol and urea to react in a one-step manner to prepare salicylnitrile. The reaction conditions are: temperature 200°C–400°C, pressure atmospheric pressure, molar ratio of phenol to urea 1:1 to 20:1, and reaction space velocity 0.01 h⁻¹. -1 ~100h -1 .

[0026] Preferably, the continuous reactor is a fixed-bed reactor or a fluidized-bed reactor, more preferably a fluidized-bed reactor.

[0027] Preferably, the raw materials phenol and urea are in solid form and are quantitatively fed into the fluidized bed reactor by a solid feeder; or the phenol and urea are heated to a molten state or dissolved in an inert solvent to form a solution, and then introduced into the reactor with the fluidizing gas. The inert solvent is selected from acetonitrile, tetrahydrofuran, dichloromethane, dichloroethane, etc., preferably acetonitrile.

[0028] Preferably, the reaction temperature is 250℃~350℃, the molar ratio of phenol to urea is 5:1 to 15:1, and the preferred reaction space velocity is 0.1h. -1 ~1h -1 .

[0029] Preferably, the fluidizing gas is selected from one or a mixture of two or more of nitrogen, hydrogen and helium, and more preferably nitrogen.

[0030] Beneficial effects

[0031] The preparation method of this invention employs a specific solid acid-base catalyst to directly prepare salicylnitrile from phenol and urea. This method effectively reduces production costs, improves production safety, reduces the amount of waste generated during the preparation of salicylnitrile using existing processes, and improves product quality. It represents a sustainable and green synthetic route. Detailed Implementation

[0032] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0033] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0034] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0035] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0036] The solid acid-base catalyst for preparing salicylamide according to the present invention comprises a basic component, an acidic component, and an auxiliary agent; wherein, the basic component mainly catalyzes the synthesis of salicylamide from urea and phenol, and the basic component is at least one selected from active MgO, CaO, and La2O3. The acidic component mainly promotes the dehydration reaction of salicylamide, and the acidic component is at least one selected from SiO2, Al2O3, or molecular sieves. The auxiliary agent increases the specific surface area, adjusts the acidity and alkalinity, and increases the stability of the catalyst, and the auxiliary agent is at least one selected from ZnO and C components. Based on 100 parts by weight of the solid acid-base catalyst, the basic component is 40-80 parts by weight, the acidic component is 10-40 parts by weight, and the auxiliary agent is 5-20 parts by weight.

[0037] In the solid acid-base catalyst according to the present invention, if the basic component is too small, it is not conducive to the amidation reaction of urea and phenol, resulting in a low urea conversion rate; if the acidic component is too small, it is not conducive to the dehydration reaction of the intermediate product salicylamide, resulting in a low selectivity of salicylnitrile; if the promoter is too small, it will affect the stability of the catalyst. Therefore, controlling the contents of the basic component, acidic component and promoter within the above-mentioned ranges results in optimal catalyst performance.

[0038] The preparation method of the solid acid-base catalyst for preparing salicylnitrile according to the present invention can be carried out by a variety of methods. As long as the final catalyst composition is consistent, these methods are all within the protection scope of the present invention.

[0039] For example, the preparation method includes the following steps: mixing 40-70 parts by weight (based on oxides) of one or a mixture of Mg, Ca, and La salts, 20-40 parts by weight (based on oxides) of aluminum sol, silica sol, or fine molecular sieve powder, 5-15 parts by weight of Zn salt (based on oxides) or C powder, an appropriate amount of water, and a binder to form a slurry; stirring the slurry evenly in a stirrer; spray-forming the slurry using a spray dryer to obtain solid microspheres; drying the microspheres at 100°C; and then calcining them in an inert gas atmosphere at 500°C-700°C to obtain a solid acid-base catalyst. Spray forming can be used to prepare wear-resistant microspheres with different particle size distributions by adjusting the spray drying process conditions (nozzle diameter, granulation temperature, pressure, slurry feed rate, concentration) and the type and amount of binder. The catalyst obtained by spray molding has parameters such as bulk density and particle size distribution that meet the requirements for optimal fluidization effect in a fluidized bed, namely: bulk density 0.4 g / mL~0.6 g / mL, particle size 75 μm~150 μm, and attrition index <3%.

[0040] The binder enhances the catalyst's abrasion resistance; the binder is guar gum and / or PEG. The amounts of water and binder are not particularly limited, as long as they promote spray molding and are consumed through volatilization during subsequent calcination.

[0041] Alternatively, the solid acid-base catalyst of the present invention can be prepared by the following method: dispersing at least one of the basic component oxide powders such as MgO, CaO and La2O3, at least one of the acid component SiO2, Al2O3 or molecular sieve powder, and at least one of the auxiliary agent ZnO and C powder components in water, heating and stirring at 25°C to 100°C for 5 to 12 hours, then evaporating the water to obtain a mixture, molding it, drying it at 100°C, and calcining it in an inert gas atmosphere at 500°C to 700°C to obtain the solid acid-base catalyst.

[0042] Furthermore, the molding process involves adding water and a binder to the dried mixture, grinding and mixing, and then extruding the mixture into strips. The binder is guar gum and / or PEG. The amount of water and binder is not particularly limited, as long as it facilitates extrusion molding and is consumed through volatilization during subsequent calcination.

[0043] Furthermore, the preparation method of salicylnitrile according to the present invention is shown in reaction formula 1 below, comprising the following steps:

[0044]

[0045] Phenol and urea, in solid, molten, or solution form, are fed into a continuous reactor with fluidized bed gas. The reactor is filled with the solid acid-base catalyst described according to the present invention, allowing phenol and urea to react in a one-step process to prepare salicylnitrile. The reaction conditions are: temperature 200°C–400°C, preferably 250°C–350°C; pressure atmospheric pressure; molar ratio of phenol to urea 1:1 to 20:1, preferably 5:1 to 15:1; and reaction space velocity 0.01 h⁻¹. -1 ~100h -1 Preferably 0.1h -1 ~1h -1 However, excessively low reaction temperature or excessively high space velocity is detrimental to urea conversion. Conversely, excessively high temperature or excessively low space velocity can easily lead to further decarboxylation and cyano self-polymerization of salicylates, thereby reducing the catalyst's selectivity for the target product, salicylates. Therefore, the reaction is optimal when the reaction temperature and space velocity are controlled within the aforementioned ranges.

[0046] The method for preparing salicylate according to the present invention employs a specific solid acid-base catalyst, enabling continuous processing. The main product after the reaction is salicylate, and the main byproducts are salicylamide and salicylic acid. Salicylate can be removed by reducing the space velocity.

[0047] In addition, the product can be washed and pulped to remove phenol and salicylic acid, and recrystallized with solvent to remove salicylamide, thus obtaining a salicylic nitrile product with high purity.

[0048] The preparation method of salicylnitrile according to this application is a continuous process with high reactant selectivity and product conversion rate. It is also simple, efficient, easy to operate, can be run continuously, is green and environmentally friendly, and produces less industrial waste. It is a sustainable, economical, and green synthetic route.

[0049] Example

[0050] In the following embodiments, the following detection instruments were used for analysis:

[0051] Quantitative testing: SHIMADZU HPLC-2010Plus liquid chromatograph;

[0052] Product identification: SHIMADZU-QP-2010-Ultra liquid chromatography-mass spectrometry;

[0053] Preparation Example 1

[0054] Solid acid-base catalysts were prepared using the following method: 318.0 g Mg(NO3)2·6H2O and 35.0 g Zn(NO3)2·6H2O were dissolved in 500 mL deionized water and stirred until dissolved. Then, 150 g silica sol (SiO2 concentration 20%), 20 g guar gum powder, and 40 g polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was added to a spray dryer using a peristaltic pump for spray molding. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 100 μm and a specific surface area of ​​254 m². 2 / g, abrasion index 1.5%.

[0055] Preparation Example 2

[0056] Solid acid-base catalysts were prepared using the following method: 210.5 g Ca(NO3)2·4H2O and 36.5 g Zn(NO3)2·6H2O were dissolved in 400 mL deionized water and stirred until dissolved. Then, 30 g of phosphoric acid-treated ZSM5 (Si / Al = 80) powder, 50 g aluminum sol (Al2O3 concentration 20%), 25 g guar gum powder, and 50 g polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was spray-dried using a peristaltic pump. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 120 μm and a specific surface area of ​​235 m². 2 / g, abrasion index 1.2%.

[0057] The phosphoric acid treatment of ZSM5 was performed as follows: ZSM5 molecular sieve particles were immersed in phosphoric acid solution at a ratio of 1g:10mL, with a phosphoric acid concentration of 0.3mol / L, for 10 hours. Then, the particles were centrifuged and washed with water until neutral. After filtration, they were placed in a drying oven at 120℃ and dried for 12 hours.

[0058] Preparation Example 3

[0059] 106.3 g of La(NO3)3·6H2O and 18.3 g of Zn(NO3)2·6H2O were dissolved in 250 mL of deionized water and stirred until dissolved. Then, 125 g of silica sol (SiO2 concentration 20%), 25 g of guar gum powder, and 20 g of polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was added to a spray dryer using a peristaltic pump for spray molding. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 125 μm and a specific surface area of ​​268 m². 2 / g, abrasion index 2.0%.

[0060] Preparation Example 4

[0061] 150.0 g of Mg(NO3)2·6H2O and 35.0 g of Zn(NO3)2·6H2O were dissolved in 250 mL of deionized water and stirred until dissolved. Then, 300 g of silica sol (SiO2 concentration 20%), 15 g of guar gum powder, and 25 g of polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was added to a spray dryer using a peristaltic pump for spray molding. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 145 μm and a specific surface area of ​​301 m². 2 / g, abrasion index 1.8%.

[0062] Preparation Example 5

[0063] Solid acid-base catalysts were prepared using the following method: 500 g of Mg(NO3)2·6H2O and 35.0 g of Zn(NO3)2·6H2O were dissolved in 800 mL of deionized water and stirred until dissolved. Then, 50 g of silica sol (SiO2 concentration 20%), 50 g of guar gum powder, and 80 g of polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was added to a spray dryer using a peristaltic pump for spray molding. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 80 μm and a specific surface area of ​​215 m². 2 / g, abrasion index 2.8%.

[0064] Preparation Example 6

[0065] Solid acid-base catalysts were prepared using the following method: 318.0 g of Mg(NO3)·6H2O was dissolved in 500 mL of deionized water and stirred until dissolved. Then, 150 g of silica sol (SiO2 concentration 20%), 30 g of guar gum powder, and 50 g of polyethylene glycol 200 were added. After stirring at room temperature for 5 hours, the resulting homogeneous sol solution was added to a spray dryer using a peristaltic pump for spray molding. The resulting microspheres were dried at 100 °C and then calcined at 550 °C in a nitrogen atmosphere to obtain a solid acid-base catalyst with an average particle size of 95 μm and a specific surface area of ​​238 m². 2 / g, abrasion index 1.8%.

[0066] Preparation Example 7

[0067] Solid acid-base catalysts were prepared using the following method: 55.0 g MgO, 30.0 g HZSM-5, 3.5 g ZnO, and 2.0 g carbon black were added to a 1 L flask, and 500 mL of deionized water was added for dispersion. The mixture was heated and stirred at 70 °C for 5 hours, then the water was evaporated. 30 g water, 10 g guar gum, and 10 g PEG were added, and the mixture was extruded into strips. The strips were then dried at 100 °C and calcined at 550 °C under a nitrogen atmosphere to obtain a grayish-black solid acid-base catalyst with a diameter of 3 mm. The strips were granulated to 3 mm, with a bulk density of 0.80 g / mL and a specific surface area of ​​222 m². 2 / g.

[0068] Preparation Example 8

[0069] Solid acid-base catalysts were prepared using the following method: 30.0 g HZSM-5, 3.5 g ZnO, and 2.0 g carbon black were added to a 1 L flask, and 300 mL of deionized water was added for dispersion. The mixture was heated and stirred at 70 °C for 5 hours, then the water was evaporated. 15 g water, 5 g guar gum, and 5 g PEG were added, and the mixture was extruded into strips. The strips were then dried at 100 °C and calcined at 550 °C under a nitrogen atmosphere to obtain a grayish-black solid acid-base catalyst with a diameter of 3 mm. The strips were granulated to 3 mm, with a bulk density of 0.80 g / mL and a specific surface area of ​​243 m². 2 / g.

[0070] Preparation Example 9

[0071] Solid acid-base catalysts were prepared using the following method: 55.0 g MgO, 3.5 g ZnO, and 2.0 g carbon black were added to a 1 L flask, and 300 mL of deionized water was added for dispersion. The mixture was heated and stirred at 70 °C for 5 hours, then the water was evaporated. 20 g water, 8 g guar gum, and 8 g PEG were added, and the mixture was extruded into strips. The strips were then dried at 100 °C and calcined at 550 °C under a nitrogen atmosphere to obtain a grayish-black solid acid-base catalyst with a diameter of 3 mm. The strips were granulated to 3 mm, with a bulk density of 0.80 g / mL and a specific surface area of ​​210 m². 2 / g, bulk density 0.80g / mL.

[0072] Example 1

[0073] Salicylic acid nitrile was prepared using the following method:

[0074] Phenol and urea (molar ratio 5:1) are fed into a fluidized bed reactor containing the solid acid-base catalysts prepared by spray drying in Examples 1 to 6 using a high-precision solid feeder. The reaction tubes of the fluidized bed reactor are straight tubes made of quartz or stainless steel, and the space velocity is 0.2 h⁻¹. -1The reaction was carried out at a controlled temperature of 300℃. After the conditions stabilized, the material flowing out of the fluidized bed reactor was collected to obtain products such as salicylnitrile. The products were washed with water, pulped, and recrystallized with an organic solvent to obtain pure salicylnitrile. The evaluation results are shown in Table 1.

[0075] Table 1 Evaluation results of fluidized bed catalysts

[0076] catalyst Runtime / h Conversion rate / % Selectivity / % molar yield / % purity / % Preparation Example 1 380 100 95.5 88 99.0 Preparation Example 2 360 96.2 93.4 84.4 99.0 Preparation Example 3 370 98.0 96.2 85.0 98.8 Preparation Example 4 355 85.3 96.0 76.2 99.2 Preparation Example 5 350 100 83.5 70.2 98.8 Preparation Example 6 300 98.2 92.6 80.2 99.2

[0077] Example 2

[0078] Salicylic acid nitrile was prepared using the following method:

[0079] The reaction conditions, such as temperature and feed rate, were modified to conduct the reaction and product post-processing in the same manner as in Example 1. Evaluation results for different reaction conditions and catalysts are shown in Table 2.

[0080] Table 2 Evaluation results of fluidized bed catalysts

[0081]

[0082] Example 3

[0083] Salicylic acid nitrile was prepared using the following method:

[0084] The molten or liquid mixture of phenol and urea (molar ratio 5:1) is fed into a reactor containing the solid acid-base catalysts prepared by extrusion in Examples 7 to 9 (10g of the solid acid-base catalysts prepared in Examples 7 to 9, pulverized and sieved to 375μm, is packed in a fixed-bed reactor tube with an inner diameter of 10mm; the fixed-bed reactor is a straight tube made of quartz or stainless steel, and the space velocity is 0.2h). -1 The reaction was carried out at a temperature controlled at 300℃. After the conditions stabilized, the material flowing out of the fluidized bed reactor was collected to obtain products such as salicylnitrile. The product was then washed with water and pulped after solvent removal, and recrystallized from the organic solvent to obtain pure salicylnitrile. The evaluation results are shown in Table 3.

[0085] Table 3 Evaluation results of fixed-bed catalysts

[0086] catalyst Conversion rate / % Selectivity / % molar yield / % purity / % Preparation Example 7 100 97.0 90.0 99.5 Preparation Example 8 2.3 98.4 - - Preparation Example 9 98.1 5.2 - -

[0087] Table 3 shows that the evaluation results for catalysts in extruded form (fixed bed) and catalysts in spray-formed and fluidized bed processes are basically equivalent. For the catalyst in Example 8, the lack of an alkaline component resulted in a lower conversion rate of the urea feedstock and a smaller amount of the intermediate product salicylamide. For the catalyst in Example 9, the lack of an acidic component resulted in lower selectivity for salicylnitrile, leading to the formation of a large amount of the intermediate product salicylamide, which could not be dehydrated into nitrile. Therefore, both acidic and alkaline components are indispensable for catalysts.

[0088] The specific embodiments described above are merely preferred embodiments for explaining this application and are not intended to limit this application. Those skilled in the art can make modifications without creative contribution as needed after reading this specification. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing salicylanilide, comprising the following steps as shown in the following reaction formula 1: Reaction formula 1 The raw materials phenol and urea in solid, molten or solution state are passed into a continuous reactor filled with solid acid-base catalyst with fluidizing gas to make salicylonitrile by one-step reaction of phenol and urea, the reaction conditions are that the temperature is 200-400 DEG C, the pressure is normal pressure, the molar ratio of phenol and urea is 1:1-20:1, the reaction space velocity is 0.01-100 h-1, and the reaction time is 0.1-10 min. -1 ~100h -1 , The solid acid-base catalyst comprises a basic component, an acidic component and an auxiliary agent, wherein the basic component is at least one selected from active MgO, CaO and La2O3, the acidic component is at least one selected from SiO2, Al2O3 or a molecular sieve, and the auxiliary agent is at least one selected from ZnO and a carbon component; based on 100 parts by weight of the solid acid-base catalyst, the basic component is 40-80 parts by weight, the acidic component is 10-40 parts by weight, and the auxiliary agent is 5-20 parts by weight.

2. The method of preparing salicylonitrile according to claim 1, characterized in that, The molecular sieve is at least one selected from Hβ, ZSM-5, SAPO-34, HY and an acid-modified molecular sieve selected from acid-modified Hβ, acid-modified ZSM-5, acid-modified SAPO-34 and acid-modified HY.

3. The method of preparing salicylonitrile according to claim 2, characterized in that, The molecular sieve is ZSM-5.

4. The method of preparing salicylonitrile according to claim 2, characterized in that, The carbon component is at least one selected from activated carbon, carbon black and a carbon component obtained by pyrolysis of an organic carbon-containing compound.

5. The method of preparing salicylonitrile according to claim 4, characterized in that, The carbon component is activated carbon.

6. The method for preparing salicylnitrile according to claim 1, characterized in that, Based on 100 parts by weight of the solid acid-base catalyst, the basic component is 40-70 parts by weight, the acidic component is 20-40 parts by weight, and the auxiliary agent is 5-15 parts by weight.

7. The method of preparing salicylonitrile according to claim 6, characterized in that, Based on 100 parts by weight of the solid acid-base catalyst, the basic component is 40-60 parts by weight, the acidic component is 20-40 parts by weight, and the auxiliary agent is 5-10 parts by weight.

8. The method of claim 2, wherein the salicylanilide is prepared by the process of claim 1. The acid-modified molecular sieve is obtained by modifying the molecular sieve in an aqueous solution of an organic acid or an inorganic acid, wherein the organic acid is one of citric acid, tartaric acid or acetic acid, the inorganic acid is one of hydrochloric acid, nitric acid or phosphoric acid, and the concentration of the aqueous solution of the organic acid or the inorganic acid is 0.05-0.5 mol / L.

9. The method for preparing salicylnitrile according to claim 2, characterized in that, The acid-modified molecular sieve is prepared by the following method, which comprises: 1) adding a molecular sieve selected from Hβ, ZSM-5, SAPO-34 or HY into an aqueous solution of an organic acid or an inorganic acid; 2) after stirring at room temperature for 5-48 h, performing suction filtration and washing until neutral, and placing into a drying oven for drying at 120℃ for 12 h; wherein the ratio of the molecular sieve to the aqueous solution of the organic acid or the inorganic acid is 1 g: 8 mL-15 mL.

10. The process for the preparation of salicylonitrile according to any one of claims 1 to 9, characterized in that, The solid acid-base catalyst is prepared by the following method, which comprises mixing 40-70 parts by weight of one or a mixture of Mg salt, Ca salt and La salt in terms of oxides, 20-40 parts by weight of aluminum sol or silicon sol or molecular sieve fine powder in terms of oxides, 5-15 parts by weight of Zn salt or carbon powder in terms of oxides, appropriate amount of water and a binder to form a slurry, uniformly stirring in a stirrer, forming into solid microspheres by a spray dryer, drying the microspheres at 100℃, and calcining in an inert gas atmosphere at 500℃-700℃ to obtain the solid acid-base catalyst; wherein the binder is Euphorbia esula gum and / or PEG.

11. The process for the preparation of salicylonitrile according to any one of claims 1 to 9, characterized in that, The solid acid-base catalyst is prepared by the following method, which comprises dispersing at least one of basic components MgO, CaO and La2O3 oxide powder, at least one of acidic components SiO2, Al2O3 or molecular sieve powder and at least one of auxiliary components ZnO, carbon powder components in water, heating and stirring at 25-100℃ for 5-12 hours, then evaporating water to obtain a mixture, performing molding treatment, then drying at 100℃, and finally calcining in an inert gas atmosphere at 500-700℃ to obtain the solid acid-base catalyst.

12. The method of claim 11, wherein the salicylanilide is prepared by the process of claim 1. The molding treatment is grinding mixing of the dried mixture with water and a binder, and extrusion molding, wherein the binder is pearl millet glue and / or PEG.

13. The method for preparing salicylnitrile according to claim 1, characterized in that, The continuous reactor is a fixed bed reactor or a fluidized bed reactor.

14. The method for preparing salicylnitrile according to claim 13, characterized in that, The continuous reactor is a fluidized bed reactor.

15. The method for preparing salicylnitrile according to claim 1, characterized in that, The raw materials phenol and urea are in solid form, which are quantitatively fed into the fluidized bed reactor by a solid feeder; or the phenol and urea are heated to a molten state or dissolved in an inert solvent to form a solution, and then the solution is fed into the reactor with fluidizing gas, and the inert solvent is selected from acetonitrile, tetrahydrofuran, dichloromethane and dichloroethane.

16. The method of claim 15, wherein the salicylanilide is prepared by the process of claim 14, wherein the process is carried out in the presence of a base. The inert solvent is acetonitrile.

17. The method for preparing salicylnitrile according to claim 1, characterized in that, The temperature of the reaction is 250°C to 350°C, the molar ratio of phenol and urea is 5:1 to 15:1, the reaction space velocity is 0.1 h -1 ~1 h -1 .

18. The method for preparing salicylnitrile according to claim 1, characterized in that, The fluidizing gas is selected from one or more than two kinds of mixture of nitrogen, hydrogen and helium.

19. The method of claim 18, wherein the salicylanilide is prepared by the process of claim 1. 0 The fluidizing gas is nitrogen.

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