A bifunctional catalyst, its preparation method and use

Abstract

The application discloses a bifunctional catalyst and a preparation method and application thereof. The bifunctional catalyst comprises an active component and a carrier, wherein the active component is loaded on the carrier; the active component comprises active component I and auxiliary active component II; the active component I comprises metal cobalt, and the auxiliary active component II comprises metal M, and M is selected from iron or tin; the carrier is a composite of silicon oxide and carbon; and the carrier has acid functional groups. The application designs a hydrogenation dehydration catalyst with a bifunctional active site of a layered structure from the microstructure design of a heterogeneous catalyst, utilizes the synergistic catalysis of hydrogenation active metal and dehydration acid functional groups to greatly improve the yield of a target product DBU, and enables the overall reaction process to be carried out under mild conditions (80 DEG C, 2.0 MPa), achieves the yield of DBU (>=95%) and has a stability of >=500 hours.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, and in particular relates to a bifunctional catalyst, its preparation method, and its application. Background Technology

[0002] 1,8-Dazabicyclo-bicyclo(5,4,0)-7-undecene (DBU) is a strong organic base, an ammonium compound with a bicyclic structure. It is a colorless or pale yellow oily liquid widely used in the synthesis of pharmaceuticals, materials, pesticides, and other chemicals. Reactions involving DBU are characterized by mild reaction conditions, few byproducts, and high selectivity. Depending on the application, DBU can be used as a catalyst, epoxy resin hardener, rust inhibitor, crosslinking agent, protectant, initiator, curing accelerator, and absorbent; it can also be formulated into high corrosion inhibitors. Furthermore, it can participate in elimination, condensation, dehydrohalogenation, desulfonation, isomerization, cyclization, esterification, and polymerization reactions. Therefore, the demand for DBU is substantial, and the market prospects are broad. With the rapid development of my country's economy and increasing emphasis on environmental protection and health safety, the demand for DBU will further increase. Currently reported methods for DBU synthesis mainly include the aziridine-lactam method, the lactam-acrylonitrile Hoffmann reaction method, and the lactone-olefinic diamine method. Compared with the lactam-acrylonitrile hydrogenation cyclization method, other methods have higher raw material prices, harsher reaction conditions, lower overall yields, and fewer research reports.

[0003]

[0004] Currently, DBU is mainly synthesized through the addition of caprolactam and acrylonitrile to form N-(β-cyanoethyl)-ε-caprolactam, followed by catalytic hydrogenation to N-(3-aminopropyl)caprolactam, and finally dehydration and cyclization. The hydrogenation and dehydration reactions are two key steps in the DBU synthesis process. Researchers have been studying these two steps separately. Existing techniques use Raney nickel as a catalyst in a reactor process to catalyze the hydrogenation of N-(β-cyanoethyl)-ε-caprolactam, but the catalyst is not reused. Another existing technique uses self-made Raney nickel as a catalyst to study the reactor-based catalytic hydrogenation process, achieving a selectivity of up to 95% for the hydrogenation product under optimal reaction conditions. Although Raney nickel as a catalyst and a reactor can currently achieve the catalytic hydrogenation of N-(β-cyanoethyl)-ε-caprolactam... However, Raney nickel catalysts are prone to pulverization during the reaction process in the reactor, and the pulverized Raney nickel catalyst is difficult to recover from the reactor, leading to difficulties in product purification. Secondly, the inherent flammability of Raney nickel catalysts in air poses a serious danger to industrial production. From both a production safety and cost reduction perspective, new hydrogenation catalysts are needed to catalyze the hydrogenation of N-(β-cyanoethyl)-ε-caprolactam, ensuring efficient DBU synthesis. Furthermore, existing technologies use p-toluenesulfonic acid as a catalyst for dehydration reactions, but p-toluenesulfonic acid, as a strong acid, severely corrodes equipment during the reaction and generates large amounts of wastewater, which is detrimental to the development of green chemistry.

[0005] Current reports on hydrogenation and dehydration reactions in DBU synthesis mainly focus on using Raney nickel catalyst systems and reactor processes for hydrogenation, followed by dehydration of the hydrogenation product using a strong liquid acid to synthesize the target product DBU. Considering the current production processes' problems such as high cost, high risk, and severe pollution from hydrogenation catalysts and dehydration processes, there is still a need to develop a low-cost, highly active, highly selective, and stable bifunctional catalyst for hydrogenation and dehydration in the DBU synthesis field. Summary of the Invention

[0006] In view of this, the present invention provides a bifunctional catalyst, its preparation method and application, the main purpose of which is to solve the technical problems of low activity, poor effect, high cost, unsafety and environmental pollution of hydrodehydration catalysts.

[0007] On one hand, the present invention provides a bifunctional catalyst, comprising:

[0008] An active component and a support, wherein the active component is loaded onto the support;

[0009] The active component includes active component I and auxiliary active component II; active component I includes metallic cobalt, and auxiliary active component II includes metallic M, where M is selected from iron or tin;

[0010] The carrier is a composite of silicon dioxide and carbon;

[0011] The carrier has acidic functional groups.

[0012] The catalyst of this invention is a bifunctional hydrodehydration catalyst with a layered structure constructed from the microscopic "inside out" perspective; cobalt and iron or tin are selected as dual active components, which work synergistically to enhance the hydrogenation active sites; the high-density acidic functional groups connected on the support can serve as dehydration reaction sites; through the microscopic combination of acidic functional groups and highly active hydrogenation sites, the two active sites synergistically catalyze to obtain a high-performance bifunctional hydrodehydration catalyst.

[0013] Optionally, the carbon in the carrier is an activated carbon ball, the surface of the activated carbon ball is connected to the acidic functional group, the silicon dioxide encapsulates the carbon ball, and the surface of the silicon dioxide is loaded with the active component.

[0014] This invention utilizes silicon dioxide to encapsulate carbon spheres containing acidic functional groups. Silicon dioxide has a rich porous structure that can uniformly load cobalt active components and iron or tin auxiliary active components. During catalysis, the reactants are transferred to the carbon spheres through the porous structure of silicon dioxide, come into contact with the acidic groups, and achieve a catalytic dehydration reaction.

[0015] Optionally, the acidic functional group includes a sulfonic acid functional group.

[0016] This invention uses sulfonic acid functional groups attached to carbon spheres to achieve catalytic dehydration reaction, and the dehydration effect of sulfonic acid functional groups is better.

[0017] Optionally, the mass percentage of the metallic cobalt on the carrier is 5% to 20%, and the mass of the metallic cobalt is expressed as the mass of elemental Co.

[0018] Optionally, the mass percentage of the metallic cobalt on the carrier is selected from any value of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a range between any two.

[0019] The cobalt content of the present invention can be adjusted according to actual needs. When its content is between 5% and 20%, it has a better catalytic effect on hydrodehydration when combined with iron or tin, and the product yield is higher.

[0020] Optionally, the mass percentage of the metal M on the carrier is 0.2% to 8%, and the mass of the metal M is expressed as the mass of elemental Fe or elemental Sn.

[0021] Optionally, the mass percentage of the metal M on the carrier is selected from any value or a range between 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7%, 7.5%, and 8%.

[0022] The content of metallic iron or tin in this invention can be adjusted according to actual needs. When its content is between 0.2% and 8%, it has a better catalytic effect on hydrogenation dehydration and a higher product yield when combined with cobalt.

[0023] Secondly, the present invention provides a method for preparing a bifunctional catalyst, the method comprising the following steps:

[0024] S1: Obtain activated carbon balls;

[0025] S2: The activated carbon balls in step S1 are modified with acidic functional groups to obtain acidified carbon balls;

[0026] S3: The acidified carbon spheres, tetraethyl orthosilicate and water mentioned in step S2 are mixed and reacted to obtain a complex of silicon oxide and carbon;

[0027] S4: The silicon oxide and carbon composite and cobalt salt in step S3 are subjected to precipitation to obtain a cobalt salt precipitate. The cobalt salt precipitate is then calcined to obtain a material with metallic cobalt loaded on the surface of the silicon oxide and carbon composite.

[0028] S5: The cobalt-loaded material on the surface of the silicon oxide and carbon composite in step S4 and the metal M salt solution are impregnated to obtain an impregnation product. The impregnation product is then calcined (II) to obtain a composite material of cobalt and metal M loaded on the surface of the silicon oxide and carbon composite, denoted as M-Co / SiO2-AC-SO3H bifunctional catalyst; wherein the metal M is Fe or Sn.

[0029] Optionally, the preparation method of the activated carbon balls in step S1 includes the following steps: aldehyde organic compounds are heated and reacted under closed conditions to obtain the activated carbon balls.

[0030] The heating reaction described above in this invention is a hydrothermal reaction, which is carried out in a hydrothermal reactor lined with polytetrafluoroethylene.

[0031] Optionally, the aldehyde organic compound is glucose and formaldehyde; the mass concentration of the glucose solution is 10% to 20%, and the mass concentration of the formaldehyde solution is 0.03% to 0.5%.

[0032] This invention uses a combination of glucose and formaldehyde to synthesize well-formed activated carbon spheres with higher activity.

[0033] Optionally, in step S1, the temperature of the heating reaction is 120–180°C, and the heating reaction time is 8–24 h.

[0034] Optionally, the heating reaction temperature is selected from any value of 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 18℃, or a range between any two; the reaction time is selected from any value of 8, 10, 12, 15, 18, 20, 24h, or a range between any two.

[0035] The water heating reaction temperature and time of the present invention can be adjusted according to actual needs, and the activated carbon balls synthesized within the above range have better performance.

[0036] Optionally, in step S2, the activated carbon balls and sulfonating agent are mixed and subjected to a sulfonation reaction to obtain acidified carbon balls modified with sulfonic acid functional groups.

[0037] The present invention modifies the surface of activated carbon spheres with sulfonic acid functional groups to achieve the dehydration of catalytic reactants.

[0038] Optionally, the sulfonating agent is selected from fuming sulfuric acid.

[0039] The present invention uses fuming sulfuric acid for sulfonation, which has a better effect. Those skilled in the art can also use it according to actual needs.

[0040] Optionally, the mass ratio of the fuming sulfuric acid to the activated carbon balls is 0.1 to 10:1.

[0041] Optionally, the mass ratio of the fuming sulfuric acid to the activated carbon balls is selected from any value or a range between 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and 10.

[0042] The reaction ratio of fuming sulfuric acid and activated carbon balls in this invention can be adjusted according to actual needs. Using the above ratio, abundant sulfonic acid groups can be obtained on the surface of the activated carbon balls, which is beneficial to the dehydration reaction.

[0043] Optionally, in step S2, the activated carbon balls and nitric acid solution are mixed and subjected to an oxidation reaction to obtain surface-activated activated carbon balls. The surface-activated activated carbon balls are then reacted with a sulfonating agent to obtain acidified carbon balls modified with sulfonic acid functional groups.

[0044] The present invention first reacts nitric acid with activated carbon balls in order to graft active functional groups such as carbonyl and hydroxyl groups onto the surface of the activated carbon balls. After the subsequent sulfonation reaction, the surface of the activated carbon balls will be loaded with more sulfonic acid groups, which is beneficial to the dehydration reaction.

[0045] Optionally, the mass concentration of the nitric acid solution is 5-10%.

[0046] Optionally, the mass ratio of the nitric acid solution to the activated carbon balls is 0.2 to 20:1.

[0047] Optionally, the mass ratio of the nitric acid solution to the activated carbon balls is any value from 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or a range between any two.

[0048] The ratio of nitric acid concentration to activated carbon balls in this invention can be adjusted according to actual needs. Using the above concentration and ratio, activated carbon balls loaded with more sulfonic acid groups can be obtained.

[0049] Optionally, in step S3, the acidified carbon balls, the tetraethyl orthosilicate, and deionized water are mixed by stirring at a temperature of 30–50°C for 12–36 hours, the product is washed 3–5 times, and dried at a temperature of 100–120°C for 5–36 hours to obtain the composite of silicon oxide and carbon.

[0050] The tetraethyl orthosilicate of the present invention undergoes a hydrolysis-gelation reaction in water. At the above-mentioned preferred temperature, after hydrolysis, the tetraethyl orthosilicate undergoes a polymerization reaction on the surface of activated carbon spheres activated by sulfonic acid groups to obtain a product of activated carbon spheres coated with silica.

[0051] Optionally, the mass ratio of the tetraethyl orthosilicate to the acidified carbon spheres is 2 to 10:1.

[0052] Optionally, the mass ratio of the tetraethyl orthosilicate to the acidified carbon spheres is selected from any value of 2, 3, 4, 5, 6, 7, 8, 9, 10 or any range between the two.

[0053] The ratio of tetraethyl orthosilicate and acidic carbon spheres in this invention can be adjusted according to actual needs. By using the above ratio, a suitable ratio of silicon dioxide-coated carbon spheres can be obtained.

[0054] Optionally, in step S4, the precipitation process includes the following steps: mixing the silicon oxide and carbon composite, cobalt salt and precipitant, precipitating reaction, stirring at 500-800 r / min for 10-24 h at a temperature of 75-85℃, washing the product 3-5 times, drying at 100-120℃ for 10-24 h and then calcining.

[0055] Optionally, the precipitant is selected from ammonium carbonate.

[0056] The precipitant of the present invention can be selected from other types of precipitants according to actual needs.

[0057] This invention utilizes a deposition method to construct highly dispersed cobalt hydrogenation active sites on the surface of silicon oxide.

[0058] Optionally, in step S4, the mass of metallic cobalt in the cobalt salt accounts for 5 to 20% of the mass of the silicon oxide and carbon composite, and the mass of metallic cobalt is calculated as the mass of elemental Co.

[0059] Optionally, in step S4, the percentage of the mass of metallic cobalt in the cobalt salt relative to the mass of the silicon oxide and carbon composite is selected from any value of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a range between any two.

[0060] Optionally, in step S4, the temperature of calcination I is 400-500°C, the calcination time is 3-5 hours, and the atmosphere of calcination I is an inactive atmosphere.

[0061] Optionally, the temperature of the roasting I is selected from any value of 400, 420, 450, 480, 500 or a range between any two; the time of the roasting I is selected from any value of 3, 3.5, 4, 4.5, 5 or a range between any two.

[0062] Optionally, in step S5, the impregnation process includes the following steps: the material on which the silicon oxide and carbon composite surface is loaded with metallic cobalt is impregnated in an impregnation solution containing metallic M salt for 10 to 72 hours to obtain an impregnated product, and the impregnated product is dried at a temperature of 60 to 120°C for 10 to 48 hours and then calcined; wherein, the impregnation solution includes a soluble salt containing metallic M and water.

[0063] Optionally, the immersion time is selected from any value of 10, 20, 30, 40, 50, 60, 70, 72h or a range between any two.

[0064] Optionally, in step S5, the temperature of calcination II is 250–500°C, the calcination time is 3–10 h, and the atmosphere of calcination II is an inactive atmosphere.

[0065] Optionally, the temperature of the roasting II is selected from any value or a range between 250, 280, 300, 320, 350, 380, 400, 420, 450, 480, and 500°C.

[0066] Optionally, in step S4, the mass of the metal in the metal M salt accounts for 0.2 to 8% of the mass of the material on which the cobalt metal is loaded on the surface of the silicon oxide and carbon composite, and the mass of the metal M is calculated as the mass of elemental Fe or elemental Sn.

[0067] Optionally, the mass of the metal in the metal M salt relative to the mass of the cobalt-loaded material on the surface of the silicon oxide and carbon composite is selected from any value or a range between 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7%, 7.5%, and 8%.

[0068] This invention utilizes an impregnation method to load the active component of the additive, iron or tin, onto the surface of silicon oxide; and uses the active component of the additive to modify the hydrogenation active sites, thereby improving the hydrogenation activity.

[0069] Optionally, the cobalt salt is selected from at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate.

[0070] Optionally, the metal-containing M salt in the impregnation method is selected from at least one of tin nitrate, tin chloride, stannous chloride, and stannous nitrate; or,

[0071] The metal-containing M salt in the impregnation method is selected from at least one of ferric nitrate, ferrous nitrate, ferric acetate, ferric chloride, and ferrous chloride.

[0072] The cobalt salt of the present invention is a soluble cobalt salt, and those skilled in the art can select other types of cobalt salts according to actual needs; the iron salt or tin salt is a soluble salt, and other types of soluble salts can be selected according to actual needs.

[0073] Optionally, the heating rate in calcination I or the heating rate in calcination II is 0.5 to 1 °C / min.

[0074] This invention provides a specific embodiment: a bifunctional catalyst for the one-step direct hydrogenation dehydration synthesis of 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene (DBU), wherein the active metal component is Co, the auxiliary metal component is Fe or Sn, and the support is a composite of silicon oxide and carbon; the active metal component, based on the mass of elemental Co, has a content of 5-20%; the auxiliary metal component, based on the mass of elemental Fe or Sn, has a content of 0.2-8%; the remainder is a composite of silicon oxide and carbon support;

[0075] The catalyst is prepared by the following steps:

[0076] (I) Dissolve glucose and formaldehyde in deionized water, stir for 0.5-3 hours, place in a hydrothermal reactor lined with polytetrafluoroethylene and hydrothermally heat at 120-180℃ for 8-24 hours to obtain micro-activated carbon balls.

[0077] (II) Place the mixture prepared in step (I) in a flask, add 5-10% nitric acid solution, stir at 50-80℃ for 5-10h to obtain surface-activated micro-active carbon spheres;

[0078] (III) Wash and filter the mixture after the reaction in step (II) with deionized water, add a certain amount of fuming sulfuric acid to the above filtered sample under ice-water bath conditions, stir for 3-6 hours, wash and filter to obtain solid sample (sulfonic acid functionalized micro carbon spheres).

[0079] (IV) Add the sample from step (III) to deionized water, stir at 500-800 r / min for 3-8 h, then add tetraethyl orthosilicate dropwise to the mixture, stir at 30-50℃ for 12-36 h, wash with deionized water 3-5 times, and dry at 100-120℃ for 5-36 h to obtain SiO2-AC-SO3H composite material.

[0080] (V) Dissolve the soluble cobalt salt and the silicon dioxide carbon sphere composite material obtained in step (IV) above in deionized water, and add ammonium carbonate solution (0.1-1.5M) dropwise under stirring (500-800 r / min) at 30-50℃ until the metal salt is completely precipitated. Stir at 500-800 r / min at 80℃ for 10-24h, wash with deionized water 3-5 times, dry at 100-120℃ for 10-24h, and calcine at 450℃ under nitrogen for 4h.

[0081] (VI) The cobalt-loaded silica-carbon sphere composite compound prepared in step (V) is impregnated in an impregnation solution for 10-72 hours, then dried at 60-120°C for 10-48 hours, and then calcined in a nitrogen furnace at 250-500°C for 3-10 hours to obtain the M-Co / SiO2-AC-SO3H bifunctional catalyst, where M is Fe or Sn. The impregnation solution is a solution formed by a soluble salt of the metal additive and water as a solvent.

[0082] In the catalyst synthesis step (I), the glucose solution has a mass fraction of 10%-20%, and the formaldehyde mass fraction is 0.03%-0.5%. In step (III), the mass ratio of fuming sulfuric acid to carbon spheres is 0.1-10. In step (IV), the mass ratio of tetraethyl orthosilicate to sulfonic acid-functionalized micro-carbon spheres is 2:1-10:1. In step (IV), the soluble cobalt salt is one or more of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate. In step (VI), the impregnation solution is one or more of tin nitrate, tin chloride, stannous chloride, and stannous nitrate, or one or more of ferric nitrate, ferrous nitrate, ferric acetate, ferric chloride, and ferrous chloride. In steps (V) and (VI), the heating rate during calcination is 0.5-1℃ / min.

[0083] This invention presents a bifunctional hydrodehydration catalyst with a layered structure, constructed from the microscopic level "from the inside out." First, glucose molecules are hinged using the binding effect of formaldehyde combined with hydrogen bonding of water molecules under hydrothermal conditions, constructing microscopically polymerized spherical carbon. Then, the benzene rings on the surface of the spherical carbon are activated using strong oxidizing nitric acid to graft various functional groups such as hydroxyl, carbonyl, and methyl groups. Finally, a sulfonation reaction is performed on the activated carbon surface to construct sulfonic acid functional groups-modified microscopic carbon spheres. These high-density sulfonic acid functional groups serve as dehydration reaction sites. Next, the functional groups on the surface of the microscopic spherical carbon react with tetraethyl orthosilicate to synthesize silica-encapsulated acidic microscopic carbon spheres. Highly dispersed cobalt hydrogenation active sites are constructed on the silica surface using a deposition precipitation method. Finally, a second metal component is used to modify the hydrogenation active sites, improving hydrogenation activity. Through the microscopic combination of sulfonic acid functional groups and highly active hydrogenation sites, synergistic catalysis yields a high-performance bifunctional hydrodehydration catalyst.

[0084] Thirdly, the present invention provides the application of the above-mentioned bifunctional catalyst in the hydrogenation and dehydration of N-(β-cyanoethyl)-ε-caprolactam to synthesize 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene.

[0085] Fourthly, the present invention provides a one-step hydrogenation-dehydration method for synthesizing 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene, the method comprising the following steps:

[0086] A mixture of N-(β-cyanoethyl)-ε-caprolactam and solvent, under the catalysis of a catalyst, undergoes a hydrogenation and dehydration reaction to yield 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene.

[0087] The catalyst is the aforementioned bifunctional catalyst.

[0088] Optionally, the catalyst is activated before use;

[0089] The activation conditions include: the catalyst is activated in a hydrogen-containing atmosphere, with a hydrogen gas space velocity of 100–3500 h⁻¹. -1 The activation pressure is 0.1–3.0 MPa, the activation temperature is 300–450 °C, the heating rate is 0.5–3 °C / min, and the activation time is 0.5–120 h.

[0090] Optionally, the reaction conditions for the hydrogenation dehydration include: a reaction temperature of 30–120°C, a reaction pressure of 0.5–5.0 MPa, and a space velocity (HSV) of 0.01–6.0 h⁻¹ for the N-(β-cyanoethyl)-ε-caprolactam solution. -1 Hydrogen space velocity is 5–3000 h⁻¹ -1 ;

[0091] The solvent in the reaction system is selected from at least one of m-xylene, o-xylene, and p-xylene.

[0092] This invention provides a specific embodiment: the application of the synthesized bifunctional catalyst in the one-step direct hydrogenation dehydration synthesis of 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene (DBU), comprising the following steps: firstly, the catalyst is packed into a packed bed reactor, and the catalyst is activated in a hydrogen-containing gas before use, under the following conditions: pressure of 0.1-3.0 MPa and hydrogen gas hourly space velocity of 100-3500 h⁻¹. -1 The activation temperature was 300-450℃, the heating rate was 0.5-3℃ / min, and the activation time was 0.5-120h. After activation, the system was adjusted to the specified reaction conditions, and a mixture of N-(β-cyanoethyl)-ε-caprolactam and solvent was pumped in. The reaction conditions were: temperature 30-120℃, pressure 0.5-5.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.01-6.0h. -1 Hydrogen space velocity is 5-3000 h⁻¹ -1 The solvent in the above-mentioned hydrogenation dehydration reaction system is one or more of m-xylene, o-xylene, and p-xylene.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] (1) The M-Co / SiO2-AC-SO3H bifunctional catalyst with a layered structure provided by the present invention is Fe or Sn, Co metal is the active component, M is the metal promoter component, SO3H is the acidic functional group, and AC is the composite support of silicon oxide and carbon.

[0095] (2) The preparation method of the bifunctional catalyst provided by the present invention is simple, low-cost, green and pollution-free, with high utilization rate of active components and good reproducibility. Combined with a continuous flow micro-packed bed reactor, the catalyst and product can be easily separated. The production process is simple, the product purity is high, and the production cost is greatly reduced.

[0096] (3) The bifunctional cobalt-based catalyst system provided by the present invention is used for the first time in the continuous flow hydrogenation and dehydration reaction of N-(β-cyanoethyl)-ε-caprolactam to prepare DBU, which makes it not only have excellent catalytic hydrogenation performance but also good dehydration performance; under mild conditions (80℃, 2.0MPa), it achieves excellent performance with DBU yield ≥95% and stability ≥500 hours. Attached Figure Description

[0097] Figure 1This is a schematic diagram of the catalyst synthesis process and a reaction mechanism diagram of the one-step synthesis of DBU by catalytic hydrogenation and dehydration according to the present invention;

[0098] Figure 2 The nitrogen physical adsorption curve of the catalyst prepared in Example 1 of this invention;

[0099] Figure 3 This is a gas chromatogram of the product in Example 1 of the present invention;

[0100] Figure 4 This is a graph showing the stability test data of the catalyst in Example 8 of the present invention. Detailed Implementation

[0101] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0102] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0103] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0104] In this embodiment of the invention, the DBU is 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene.

[0105] Example 1

[0106] Preparation of catalysts:

[0107] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0108] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0109] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0110] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an iron nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 1-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0111] Preparation of DBU:

[0112] The above-mentioned 1-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas space velocity 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products are collected at the reactor outlet and analyzed using gas chromatography. The chromatogram of the reaction products is shown below. Figure 3 As shown, the raw material N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 100% and a selectivity of 95.8% for the target product: DBU.

[0113] Example 2

[0114] Preparation of catalysts:

[0115] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 60 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 20 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres, followed by stirring for 3 hours. The mixture was then washed and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0116] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0117] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0118] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an ferric nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain the 2-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0119] Preparation of DBU:

[0120] The above-mentioned 2-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas space velocity 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 100% and a selectivity of 96.6% for the target product DBU.

[0121] Example 3

[0122] Preparation of catalysts:

[0123] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0124] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0125] 7 g of cobalt acetate and 3 g of SiO2-AC-SO3H were dissolved in 100 mL of deionized water. Ammonium carbonate solution (0.3 mol / L) was added dropwise under stirring (600 r / min) at 50 °C until cobalt ions were completely precipitated. The mixture was stirred at 600 r / min for 12 h at 80 °C, washed five times with deionized water, dried at 120 °C for 12 h, and calcined at 450 °C under nitrogen for 4 h to obtain the Co / SiO2-AC-SO3H sample.

[0126] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an ferric nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 3-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0127] Preparation of DBU:

[0128] First, the 3-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity (LISH) 0.45h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 100% and a selectivity of 95.2% for the target product DBU.

[0129] Example 4

[0130] Preparation of catalysts:

[0131] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0132] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0133] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0134] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in a tin nitrate impregnation solution containing 0.1 g Sn for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 4-Sn-Co / SiO2-AC-SO3H bifunctional catalyst.

[0135] Preparation of DBU:

[0136] First, the 4-Sn-Co / SiO2-AC-SO3H bifunctional catalyst was packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 98% and a selectivity of 93.8% for the target product DBU.

[0137] Example 5

[0138] Preparation of catalysts:

[0139] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0140] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0141] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0142] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an iron nitrate impregnation solution containing 0.05 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 5-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0143] Preparation of DBU:

[0144] The above-mentioned 5-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen under the following conditions: pressure 0.1 MPa, hydrogen gas space velocity 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 97.8% and a selectivity of 92.7% for the target product DBU.

[0145] Example 6

[0146] Preparation of catalysts:

[0147] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0148] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). Then, 30 g of tetraethyl orthosilicate was added dropwise, and the mixture was stirred at 50 °C for 24 hours (600 r / min). After filtration and washing with deionized water 5 times, the mixture was dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0149] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0150] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an ferric nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 6-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0151] Preparation of DBU:

[0152] First, the 6-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 96.8% and a selectivity of 93.9% for the target product DBU.

[0153] Example 7

[0154] Preparation of catalysts:

[0155] 10 g of glucose and 0.08 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 150 °C for 15 hours. After cooling to room temperature, the mixture was transferred to a flask. 30 mL of 6% nitric acid solution was added dropwise to the flask, and the mixture was stirred at 60 °C for 8 hours. The flask was then washed 5 times with deionized water. Under ice-water bath conditions, 10 mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres. The mixture was then stirred for 3 hours, washed, and filtered to obtain micro-carbon spheres containing sulfonic acid functional groups (AC-SO3H).

[0156] Subsequently, the microscopic carbon spheres with sulfonic acid functional groups (AC-SO3H) were added to deionized water and stirred at room temperature for 5 hours (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 hours (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 hours to obtain SiO2-AC-SO3H.

[0157] Dissolve 6g of cobalt acetate and 3g of SiO2-AC-SO3H in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash five times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC-SO3H sample.

[0158] Two grams of the above Co / SiO2-AC-SO3H sample were impregnated in an ferric nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain a 7-Fe-Co / SiO2-AC-SO3H bifunctional catalyst.

[0159] Preparation of DBU: First, a 7-Fe-Co / SiO2-AC-SO3H bifunctional catalyst was packed into a micro-packed bed reactor. The catalyst was activated in hydrogen gas before use under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 98.9% and a selectivity of 94.8% for the target product DBU.

[0160] Example 8

[0161] The 1-Fe-Co / SiO2-AC-SO3H bifunctional catalyst from Example 1 was packed into a micro-packed bed reactor for catalyst stability testing. Before use, the catalyst was activated with hydrogen under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 .

[0162] like Figure 4 As shown, the catalyst performance remained stable at a conversion rate of 100% and a selectivity of 95-97% for the target product, DBU. The catalyst maintained stable performance after 500 hours of continuous reaction.

[0163] Comparative Example 1

[0164] 10 g of glucose and 0.1 g of formaldehyde were added to 60 mL of deionized water and stirred for 1 hour (500 r / min). The mixture was then transferred to a 100 mL hydrothermal polymerization reactor lined with polytetrafluoroethylene and hydrothermally treated at 150 °C for 15 h. After cooling to room temperature, the mixture was transferred to a flask, washed, and filtered to obtain micro-carbon spheres (AC). Subsequently, the micro-carbon spheres (AC) were added to deionized water and stirred at room temperature for 5 h (600 r / min). 40 g of tetraethyl orthosilicate was added dropwise, and stirring was continued at 50 °C for 24 h (600 r / min). The mixture was then filtered, washed 5 times with deionized water, and dried at 120 °C for 5 h to obtain SiO2-AC.

[0165] Dissolve 6g of cobalt acetate and 3g of SiO2-AC in 100mL of deionized water. Add ammonium carbonate solution (0.3mol / L) dropwise under stirring (600r / min) at 50℃ until cobalt ions are completely precipitated. Stir at 600r / min for 12h at 80℃, wash 5 times with deionized water, dry at 120℃ for 12h, and calcine at 450℃ under nitrogen for 4h to obtain the Co / SiO2-AC sample.

[0166] Two grams of the above Co / SiO2-AC sample were impregnated in an ferric nitrate impregnation solution containing 0.1 g Fe for 24 h, then dried at 100 °C for 12 h, and then calcined in a nitrogen furnace at 350 °C for 3 h to obtain the R1-Fe-Co / SiO2-AC bifunctional catalyst.

[0167] The R1-Fe-Co / SiO2-AC bifunctional catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The raw material N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 90%. The selectivity of the target product DBU was only 5.6%, and most of the product was converted to N-(3-aminopropyl)caprolactam with a selectivity of 82.6%.

[0168] Comparative Example 2

[0169] The strong acid resin sample (D001) from Dalian Dandong Mingzhu was impregnated in an impregnation solution for 10 hours. The impregnation solution was an aqueous solution of cobalt acetate and ferric nitrate. The contents of cobalt acetate and ferric nitrate were the same as those of Co and Fe in the catalyst in Example 1. The sample was then dried at 120°C for 5 hours and calcined in a muffle furnace at 450°C for 4 hours at a calcination heating rate of 1°C / min to obtain the R2-Fe-Co / AC catalyst.

[0170] The R2-Fe-Co / AC catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 42% and a selectivity of only 25% for the target product DBU.

[0171] Comparative Example 3

[0172] 5g of coconut shell activated carbon was placed in a flask, and 30mL of 6% nitric acid solution was added dropwise to the flask. The mixture was stirred at 60℃ for 8 hours and washed 5 times with deionized water. Under ice-water bath conditions, 10mL of fuming sulfuric acid was added dropwise to the activated micro-carbon spheres, and then stirred for 3 hours. After washing and filtration, carbon spheres containing sulfonic acid functional groups (R3-AC-SO3H) were obtained.

[0173] R3-AC-SO3H was impregnated in an impregnation solution for 10 h, wherein the impregnation solution was an aqueous solution of cobalt acetate and ferric nitrate, and the contents of cobalt acetate and ferric nitrate were the same as those of Co and Fe in the catalyst in Example 1. Then it was dried at 120 °C for 5 h and calcined in a nitrogen furnace at 450 °C for 4 h at a calcination heating rate of 1 °C / min to obtain the R3-Fe-Co / AC-SO3H catalyst.

[0174] The R3-Fe-Co / AC-SO3H catalyst was first packed into a micro-packed bed reactor. Before use, the catalyst was activated in hydrogen gas under the following conditions: pressure 0.1 MPa, hydrogen gas hourly space velocity (HHSV) 1000 h⁻¹. -1 The activation temperature was 400℃, the heating rate was 0.5℃ / min, and the activation time was 3h. After activation, the system was adjusted to the specified reaction conditions, and a 15wt.% N-(β-cyanoethyl)-ε-caprolactam xylene solution was pumped in. The reaction conditions were: temperature 80℃, pressure 2.0MPa, and N-(β-cyanoethyl)-ε-caprolactam liquid hourly space velocity 0.35h⁻¹. -1 The hydrogen space velocity is 500 h⁻¹. -1 The reaction products were collected at the reactor outlet and analyzed by gas chromatography. The feedstock N-(β-cyanoethyl)-ε-caprolactam underwent a one-step hydrogenation dehydration reaction catalyzed by a catalyst, with a conversion rate of 38%, while the selectivity for the target product DBU was only 28%.

[0175] Results of the preparation of DBU by N-(β-cyanoethyl)-ε-caprolactam xylene catalyzed by the catalyst in Examples 1-7 of this invention:

[0176] Catalytic effect of Example 1: conversion rate 100%, DBU selectivity 95.8%.

[0177] Catalytic effect of Example 2: conversion rate 100%, DBU selectivity 96.6%.

[0178] Catalytic effect of Example 3: conversion rate 100%, DBU selectivity 95.2%.

[0179] Catalytic effect of Example 4: conversion rate 98%, DBU selectivity 93.8%.

[0180] Catalytic effect of Example 5: conversion rate 97.8%, DBU selectivity 92.7%.

[0181] Catalytic effect of Example 6: conversion rate 96.8%, DBU selectivity 93.9%.

[0182] Catalytic performance of Example 7: conversion rate 98.9%, DBU selectivity 94.8%.

[0183] Figure 3 The DBU selectivity of the catalyst prepared in Example 1 of this invention is 95.8%.

[0184] The experimental results above show that the bifunctional catalyst prepared in this invention, when used in the production of DBU from N-(β-cyanoethyl)-ε-caprolactam xylene, achieves a reactant conversion rate of 96.8%–100% and a DBU selectivity of 92.7%–96.6%, demonstrating that the catalyst has excellent catalytic performance.

[0185] Figure 4 The bifunctional catalyst prepared in this invention was used in the production of DBU from N-(β-cyanoethyl)-ε-caprolactam xylene. After 500 hours of operation, the reactant conversion rate remained at 96.8%–100%, and the DBU selectivity remained above 95%, indicating that the catalyst has high activity and is stable.

[0186] Compared with Example 1: In Comparative Example 1, the carbon spheres were not acidified, and the DBU selectivity was only 5.6%, while the product selectivity after hydrogenation of the reactants was 82.6%. This indicates that the reactants underwent a very small degree of dehydration reaction, further demonstrating that the acidic groups introduced on the carbon spheres can catalyze the dehydration reaction with good effect.

[0187] Compared with Example 1, Comparative Example 2 uses a strong acid resin as the support, with a reactant conversion rate of 42% and a DBU selectivity of 25%. This indicates that the hydrogenation and dehydration reactions are both poor because it does not introduce silica, which cannot effectively disperse the active components on the catalyst surface. Therefore, the catalyst activity is not high, further demonstrating that the composite silica on the strong acid support affects the metal catalytic activity. Comparative Example 2 also does not introduce acidic groups. Although the strong acid support is acidic, the acidity does not promote the dehydration effect as well as the dehydration effect of the activated carbon balls with sulfonic acid groups prepared in this invention.

[0188] Compared with Example 1, Comparative Example 3 used coconut shell activated carbon, with a DBU selectivity of 28% and a reactant conversion rate of 38%. This indicates that the coconut shell activated carbon has a poor effect on loading active metals and a poor catalytic hydrogenation effect. Even with the introduction of sulfonic acid groups, the dehydration effect of coconut shell activated carbon after connecting sulfonic acid groups is poor. Since it does not have silica composite on the coconut shell activated carbon, its loading effect on metal active components is poor, which affects the hydrogenation catalytic effect.

[0189] The above demonstrates that the bifunctional catalyst prepared by the method of this invention can be successfully used in a one-step hydrogenation and dehydration synthesis of 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene, with excellent results.

[0190] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A bifunctional catalyst, characterized in that, The bifunctional catalyst includes: An active component and a support, wherein the active component is loaded onto the support; The active component includes active component I and auxiliary active component II; active component I includes metallic cobalt, and auxiliary active component II includes metallic M, where M is selected from iron or tin; The carrier is a composite of silicon dioxide and carbon; The characteristic feature is that the carbon in the carrier is an activated carbon ball, and the surface of the activated carbon ball is connected with acidic functional groups, including sulfonic acid functional groups. The silicon dioxide encapsulates the carbon spheres, and the surface of the silicon dioxide is loaded with the active component.

2. The bifunctional catalyst according to claim 1, characterized in that: The mass percentage of metallic cobalt on the carrier is 5% to 20%, and the mass of metallic cobalt is based on the mass of elemental Co. The mass percentage of the metal M on the carrier is 0.2% to 8%, and the mass of the metal M is expressed as the mass of elemental Fe or elemental Sn.

3. A method for preparing a bifunctional catalyst according to any one of claims 1 to 2, characterized in that, The preparation method includes the following steps: S1: Obtain activated carbon balls; S2: The activated carbon balls in step S1 are modified with acidic functional groups to obtain acidified carbon balls; S3: The acidified carbon spheres, tetraethyl orthosilicate and water mentioned in step S2 are mixed and reacted to obtain a complex of silicon oxide and carbon; S4: The silicon oxide and carbon composite and cobalt salt in step S3 are subjected to precipitation to obtain a cobalt salt precipitate. The cobalt salt precipitate is then calcined to obtain a material with metallic cobalt loaded on the surface of the silicon oxide and carbon composite. S5: The cobalt-loaded material on the surface of the silicon oxide and carbon composite in step S4 and the metal M salt solution are impregnated to obtain an impregnation product. The impregnation product is then calcined (II) to obtain a composite material of cobalt and metal M loaded on the surface of the silicon oxide and carbon composite, denoted as M-Co / SiO2-AC-SO3H bifunctional catalyst; wherein the metal M is Fe or Sn.

4. The method for preparing a bifunctional catalyst according to claim 3, characterized in that, The preparation method of the activated carbon balls in step S1 includes the following steps: aldehyde organic compounds are heated and reacted under closed conditions to obtain the activated carbon balls; The aldehyde organic compounds are glucose and formaldehyde; the mass concentration of glucose is 10% to 20%, and the mass concentration of formaldehyde is 0.03% to 0.5%. In step S1, the temperature of the heating reaction is 120 ~ 180 ℃, and the heating reaction time is 8 ~ 24 h; In step S2, the activated carbon balls and sulfonating agent are mixed and subjected to a sulfonation reaction to obtain acidified carbon balls modified with sulfonic acid functional groups. The sulfonating agent is selected from fuming sulfuric acid; The mass ratio of the fuming sulfuric acid to the activated carbon balls is 0.1 to 10:

1.

5. The method for preparing a bifunctional catalyst according to claim 4, characterized in that, In step S2, the activated carbon balls and nitric acid solution are mixed and subjected to an oxidation reaction to obtain surface-activated activated carbon balls. The surface-activated activated carbon balls are then reacted with a sulfonating agent to obtain acidified carbon balls modified with sulfonic acid functional groups. The mass concentration of the nitric acid solution is 5% to 10%. The mass ratio of the nitric acid solution to the activated carbon balls is 0.2 to 20:

1.

6. The method for preparing a bifunctional catalyst according to claim 3, characterized in that, In step S3, the acidified carbon balls, the tetraethyl orthosilicate and deionized water are mixed by stirring at a temperature of 30-50 °C for 12-36 h, the product is washed 3-5 times and dried at a temperature of 100-120 °C for 5-36 h to obtain the composite of silicon oxide and carbon. The mass ratio of the tetraethyl orthosilicate to the acidified carbon spheres is 2 to 10:1; In step S4, the precipitation process includes the following steps: mixing the silicon oxide and carbon composite, cobalt salt and precipitant, precipitating the mixture, stirring at 500-800 r / min for 10-24 h at a temperature of 75-85 ℃, washing the product 3-5 times, drying at 100-120 ℃ for 10-24 h and then calcining; the precipitant is selected from ammonium carbonate. In step S4, the temperature of calcination I is 400 ~ 500 ℃, the calcination time is 3 ~ 5 h, and the atmosphere of calcination I is an inactive atmosphere. The heating rate in the calcination I is 0.5~1℃ / min; The mass of metallic cobalt in the cobalt salt accounts for 5% to 20% of the mass of the silicon oxide and carbon composite, and the mass of metallic cobalt is based on the mass of elemental Co. The cobalt salt is selected from at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate.

7. The method for preparing a bifunctional catalyst according to claim 6, characterized in that, In step S5, the impregnation process includes the following steps: the material with cobalt metal loaded on the surface of the silicon oxide and carbon composite is impregnated in an impregnation solution containing metal M salt for 10 to 72 h to obtain an impregnated product, and the impregnated product is dried at a temperature of 60 to 120 °C for 10 to 48 h and then calcined II; wherein, the impregnation solution includes a soluble salt containing metal M and water; In step S5, the temperature of calcination II is 250 ~ 500 ℃, the calcination time of calcination II is 3 ~ 10 h, and the atmosphere of calcination II is an inactive atmosphere; The mass of the metal in the metal M salt accounts for 0.2% to 8% of the mass of the cobalt-loaded material on the surface of the silicon oxide and carbon composite, and the mass of the metal M is based on the mass of elemental Fe or elemental Sn. The cobalt salt is selected from at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate; The metal M salt in the impregnation method is selected from at least one of tin nitrate, tin chloride, stannous chloride and stannous nitrate, or from at least one of ferric nitrate, ferrous nitrate, ferric acetate, ferric chloride and ferrous chloride; The heating rate in the calcination II process is 0.5~1℃ / min.

8. The use of the bifunctional catalyst according to any one of claims 1 to 2 in the synthesis of 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene by hydrogenation and dehydration of N-(β-cyanoethyl)-ε-caprolactam.

9. A one-step hydrogenation dehydration method for synthesizing 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene, characterized in that, The method includes the following steps: A mixture of N-(β-cyanoethyl)-ε-caprolactam and solvent, under the catalysis of a catalyst, undergoes a hydrogenation and dehydration reaction to yield 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene. The catalyst is a bifunctional catalyst as described in any one of claims 1 to 2.

10. The method for one-step hydrogenation dehydration synthesis of 1,8-diazabicyclo-bicyclo(5,4,0)-7-undecene according to claim 9, characterized in that, The catalyst is activated before use; The activation conditions include: activation of the catalyst in a hydrogen-containing atmosphere with a hydrogen gas space velocity of 100-3500 h⁻¹. -1 The activation pressure is 0.1 ~ 3.0 MPa, the activation temperature is 300 ~ 450 ℃, the heating rate is 0.5 ~ 3 ℃ / min, and the activation time is 0.5 ~ 120 h; The reaction conditions for the hydrogenation dehydration include: a reaction temperature of 30–120 °C, a reaction pressure of 0.5–5.0 MPa, and a space velocity (HSV) of 0.01–6.0 h⁻¹ for the N-(β-cyanoethyl)-ε-caprolactam solution. -1 The hydrogen space velocity is 5 ~ 3000 h⁻¹ -1 ; The solvent in the reaction system is selected from at least one of m-xylene, o-xylene, and p-xylene.

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