Cu-si-al bifunctional catalyst, preparation method thereof and method for directly preparing ketone and enone from olefin

Abstract

The present application relates to a Cu-Si-Al bifunctional catalyst, which comprises a carrier and an active component; the carrier is amorphous aluminum gel, and the active component is a copper-encapsulated silicon-aluminum molecular sieve. The copper provides dehydrogenation active centers for the Cu-Si-Al bifunctional catalyst; the carrier and the silicon-aluminum molecular sieve provide Lewis acid centers and Bronsted acid centers for the Cu-Si-Al bifunctional catalyst; the amount of Lewis acid centers is 10.7-237.4 mu mol / g, and the amount of Bronsted acid centers is 1.3-46.9 mu mol / g. The present application also provides a preparation method of the Cu-Si-Al bifunctional catalyst. The Cu-Si-Al bifunctional catalyst is applied to a method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, solves the problems of low conversion rate and high toxicity in the process of preparing cyclic ketones and cyclic enones from cyclic olefins, improves the effective utilization rate of cyclic olefins and the production efficiency of the products cyclic ketones and cyclic enones, reduces the recycling energy consumption of the substrate cyclic olefins, and makes the production process more economical.

Description

Technical Field

[0001] This invention belongs to the technical field of organic ketone and organic enone preparation, specifically relating to a molecular sieve for the direct preparation of ketones and enones from olefins and its preparation method. Background Technology

[0002] Ketones are compounds in which a carbonyl group is attached to two hydrocarbon groups. Due to the polarization effect of the carbonyl group, ketones are chemically very reactive, readily undergoing addition reactions with nucleophiles such as hydrogen cyanide, Grignard reagents, hydroxylamine, and alcohols, and can be reduced to the corresponding alcohols. Furthermore, ketones containing α-H readily undergo halogenation reactions, while ketones with methyl groups readily undergo haloform reactions under alkaline conditions. In addition, low-carbon ketones, such as acetone and methyl ethyl ketone, have good solubility and are often used as solvents. Therefore, organic ketones have a wide range of applications, especially acetone and cyclohexanone, which are important chemical raw materials.

[0003] Enones are a class of organic molecules that possess both olefin double bonds and ketone groups. The olefin double bonds in the molecular structure of enones endow them with unique properties distinct from traditional ketones, making them more reactive and thus applicable to a wider range of fields. Enones are frequently used as electrophiles in organic reactions, participating in various reactions such as dominant or recessive alkylation, arylation, hydroxyalkylation, and carboxylation. Furthermore, due to their polar structure, enones can form horseshoe-shaped molecules, facilitating the preparation of chiral products. In the pharmaceutical field, some compounds containing enone groups are considered potential precursors for antibacterial and antiviral drugs. In materials science, the synthesis and applications of enones have been extensively studied in various areas, such as the synthesis of high-performance polyesters, resins, coatings, polymers, and surfactants.

[0004] Taking cyclohexanone and cyclohexenone as examples, cyclohexanone, as an important basic chemical raw material, can be used to produce bulk chemical products such as adipic acid, caprolactam, and caprolactone. Cyclohexenone is also an important chemical intermediate, widely used in the synthesis of fine chemical products such as fragrances, perfumes, pharmaceuticals, and pesticides.

[0005] Currently, there are two methods for producing cyclohexanone: cyclohexane oxidation and cyclohexene hydration. In the oxidation process, cyclohexane is oxidized to produce a mixed solution of cyclohexanol and cyclohexanone. In the hydration process, cyclohexene is hydrated to cyclohexanol under the action of an acidic catalyst, and then the cyclohexanol is dehydrogenated to cyclohexanone. For the cyclohexene hydration process, the conversion rate is only about 10%, which limits the improvement of cyclohexanone production efficiency and significantly increases the energy consumption of this process.

[0006] On the other hand, cyclohexenone is mainly prepared by the oxidation of cyclohexene, but chromium oxide catalysts are highly toxic and the oxidation products have low selectivity and are difficult to separate. Therefore, an efficient synthetic method for cyclohexenone still needs to be explored. Summary of the Invention

[0007] To address the problems of low conversion rate and high toxicity in current processes for the hydration of cyclic olefins to produce cyclic ketones and cyclic enones, this invention provides a Cu-Si-Al bifunctional catalyst and a method for directly catalyzing the conversion of cyclic olefins to co-produce cyclic ketones and cyclic enones.

[0008] In a first aspect, the present invention provides a Cu-Si-Al bifunctional catalyst. The Cu-Si-Al bifunctional catalyst comprises a support and an active component; the support is an amorphous aluminum gel, and the active component is a copper-encapsulated silicon-aluminum molecular sieve.

[0009] Specifically, the pore volume of the Cu-Si-Al bifunctional catalyst is 0.05–0.60 cm³. 3 / g, preferably 0.11~0.47cm 3 / g, more preferably 0.16~0.39cm 3 / g; the specific surface area of ​​the Cu-Si-Al bifunctional catalyst is 40-511 m². 2 / g, preferably 81-459m 2 / g, further preferably 129-377m 2 / g. The amorphous alumina gel carrier and silica-alumina molecular sieve serve as the main structure of the bifunctional catalyst, forming a hierarchical porous structure.

[0010] Furthermore, the copper provides a dehydrogenation active center for the Cu-Si-Al bifunctional catalyst, and the copper is encapsulated within the silicon-aluminum molecular sieve crystal; the support and the silicon-aluminum molecular sieve provide Lewis acid centers and Bronsted acid centers for the Cu-Si-Al bifunctional catalyst; the Lewis acid center has an acidity of 10.7–237.4 μmol / g, preferably 16.9–194.8 μmol / g; the Bronsted acid center has an acidity of 1.3–46.9 μmol / g, preferably 2.9–36.7 μmol / g.

[0011] Molecular sieves, with their molecular-scale crystalline channel structure and unique Lewis / Bronsted acidity, are commonly used heterogeneous catalytic materials in petrochemical processes. The Cu-Si-Al bifunctional catalyst provided by this invention possesses Lewis and Bronsted acid centers that can coordinate with carbon-carbon double bonds and activate olefin molecules. Furthermore, through the synergistic effect of ketone nanoparticles as dehydrogenation active centers, cyclic olefins not only undergo hydration reactions with water, but the hydration products can also be further dehydrogenated to generate cyclic ketones and cyclic enones, achieving the direct conversion of cyclic olefins into cyclic ketones and cyclic enones.

[0012] In a second aspect, the present invention also provides a method for preparing the Cu-Si-Al bifunctional catalyst described above.

[0013] Specifically, the preparation method of the Cu-Si-Al bifunctional catalyst includes the following steps:

[0014] Step 1: Mix silicon source, aluminum source I, copper source, additive I, dispersant, alkaloid compound, alkali source, and H2O in a certain proportion to obtain a mixed system; perform hydrothermal treatment on the mixed system at 50-190℃ for 3-10 days, and then filter and dry to obtain silicon-aluminum molecular sieve encapsulated with copper oxide.

[0015] Step 2: Mix aluminum source II, acid source, the encapsulated copper oxide silica-alumina molecular sieve obtained in Step 1, guar gum powder, additive II, pore-forming agent, and H2O in a certain proportion to prepare a catalyst precursor; shape the catalyst precursor, dry it, calcine it at 400-850℃ for 1-6 hours, and reduce it in H2 atmosphere at 160-300℃ for 12-72 hours to obtain a Cu-Si-Al bifunctional catalyst containing encapsulated copper silica-alumina molecular sieve.

[0016] Furthermore, in step one, the silicon source is selected from at least one of organosilicates, silica gel, fumed silica, and silica sol; in order to reduce the influence of heteroatoms in the silicon source on the molecular sieve crystallization product, a single silicon source is preferred; it is further preferred to select at least one of organosilicates such as methyl orthosilicate, isopropyl silicate, ethyl silicate, tetraethoxysilane, and tetraethyl orthosilicate.

[0017] Furthermore, in step one, the aluminum source I is selected from at least one of aluminum nitrate, aluminum chloride, aluminum hydroxide, boehmite, acidic aluminum sol, and alkaline aluminum sol.

[0018] Furthermore, in step one, the copper source is selected from at least one of copper nitrate, copper chloride, tetraphenylporphyrin copper, and copper acetylacetonate.

[0019] Furthermore, in step one, the auxiliary agent I has different electronegativity from silicon and aluminum. The auxiliary agent is selected from those containing at least one of one or more compounds of Ag, Ni, Au, Zn, Pd, and Pt; preferably, it contains at least one of one or two compounds of Ag and Au; and more preferably, it contains at least one of silver nitrate and chloroauric acid.

[0020] Furthermore, to improve the performance of the silica-alumina molecular sieve, the dispersant in step one is a soluble compound containing nitrogen, sulfur, or other substances with lone pairs of electrons. The dispersant is selected from at least one of ethylamine, ethylenediamine, propylenediamine, hexamethylenediamine, aniline, pyridine, thiophene, thiol, thiophenol, and thioether; preferably at least one of ethylenediamine, hexamethylenediamine, and aniline.

[0021] Furthermore, the alkaloid compound in step one contains at least one of the functional groups of primary amine, secondary amine, tertiary amine, and quaternary amine.

[0022] Specifically, in step one, the alkaloid compound is selected from at least one of tryptophan, tryptophan, 5-hydroxytryptamine, ephedrine, and leonurine; preferably, it is a mixture of tryptophan and leonurine, wherein the molar ratio of tryptophan to leonurine in the mixture is (0.1-10):1.

[0023] Further, in the step, the alkali source is selected from at least one of organic or inorganic alkalis, preferably at least one of alkali metal hydroxides, ammonia, urea, hydrazine hydrate, sodium carbonate, sodium bicarbonate, aliphatic amines, aliphatic alcoholic amines, and quaternary ammonium bases.

[0024] Specifically, the general structural formula of the quaternary ammonium base is:

[0025]

[0026] Wherein, R1, R2, R3, and R4 are at least one of C1-C4 alkyl groups, wherein the C1-C4 alkyl groups are selected from at least one of C1-C4 straight-chain alkyl groups and C3-C4 branched-chain alkyl groups. R1, R2, R3, or R4 may independently be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl.

[0027] Specifically, the aliphatic amine has the general structural formula R5(NH2)n, where n is an integer of 1 or 2. When n is 1, R5 is at least one of C1-C6 alkyl groups, selected from at least one of C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl, or n-hexyl. When n is 2, R5 is at least one of C1-C6 alkylene groups, selected from at least one of C1-C6 straight-chain alkylene groups and C3-C6 branched alkylene groups, such as methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene.

[0028] Preferably, the alkali source is selected from at least one of tetraethylammonium hydroxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tripropylamine, triethylamine, tributylammonium, hexylamine, and hexamethylenediamine; more preferably, it is selected from at least one of tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

[0029] Further, in step one, the molar ratio of silicon source, aluminum source I, copper source, additive I, dispersant, alkaloid compound, alkali source, and H2O is 1:(0.001-0.3):(0.001-0.5):(0-0.1):(0.03-2):(0.05-3):(0.1-5):(5-500);

[0030] The preferred ratio is 1: (0.005~0.2): (0.005~0.4): (0.001~0.08): (0.05~1.6): (0.08~2.2): (0.15~3): (10~200);

[0031] A further preferred ratio is 1: (0.01-0.16): (0.01-0.25): (0.01-0.06): (0.08-1.2): (0.11-1.6): (0.2-1.8): (15-80);

[0032] Among them, the silicon source is SiO2, and the alkali source is N or OH. - count.

[0033] The temperature and time of the hydrothermal reaction in step one are important factors affecting the crystal form, crystal size, and morphology of the hydrothermal product. Specifically, the hydrothermal treatment temperature in step two is 50–190°C, and the hydrothermal treatment time is 3–10 days; preferably, the hydrothermal treatment temperature is 70–170°C, and the hydrothermal treatment time is 5–8 days; the hydrothermal treatment conditions are further preferably: first, hydrothermal treatment at a temperature of 160–190°C for 0.5–1 day; then, hydrothermal treatment at a temperature of 90–120°C for 1–2 days. Furthermore, the pressure of the hydrothermal reaction system is another important factor affecting the crystal form and crystallization rate of the product, and the self-generated pressure of the reaction system depends on the size of the empty volume in the reactor. To improve the efficiency of the hydrothermal reaction, preferably, the total volume of the mixing system in step one is 60–85% of the reactor capacity, wherein the reactor is preferably a polytetrafluoroethylene (PTFE) reactor.

[0034] Specifically, the drying temperature in step one is 80–120°C.

[0035] Specifically, the aluminum source II mentioned in step two is selected from at least one of boehmite, aluminum hydroxide, and aluminum sol; preferably at least one of boehmite and aluminum sol.

[0036] Specifically, the acid source in step two is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, adipic acid, acetic acid, isononanoic acid, and isovaleric acid; preferably, at least one of nitric acid and isononanoic acid.

[0037] Specifically, in step two, the auxiliary agent II is selected from at least one compound containing at least one ion of alkali metal ions or alkaline earth metal ions; further selected from compounds containing Na + K + 、Rb + Cs + Mg 2+ Ca 2+ Ba 2+ At least one of the compounds containing at least one ion; preferably Na + K + 、Rb + Cs + Mg 2+ Ca 2+ Ba 2+ Nitrates or chlorides; more preferably containing Na + K + Cs + At least one of the compounds containing at least one ion, more preferably a nitrate or chloride of the aforementioned particles. Using alkali metal or alkaline earth metal ions as additives can prevent side reactions initiated by the Bronsted acidity of the amorphous aluminum gel carrier.

[0038] After aluminum source II is dissolved by acid source, it is calcined to form amorphous aluminum gel, which together with the silicon-aluminum molecular sieve obtained in step one serves as the main structure of the bifunctional catalyst. After molding treatment, the bifunctional catalyst is formed into a specific shape and has a certain strength to ensure the stability of the bifunctional catalyst during long-term use, while preventing excessive resistance of materials during the process of passing through the catalyst bed.

[0039] Specifically, the pore-forming agent in step two is selected from at least one of starch, cellulose, lignin, or modified compounds of starch / cellulose / lignin; preferably, it is selected from at least one of cellulose, lignin, or modified compounds of cellulose / lignin. The pore-forming agent is removed after calcination, giving the amorphous alumina gel, which serves as the bifunctional catalyst support, a porous structure, further increasing the specific surface area of ​​the bifunctional catalyst and improving its catalytic efficiency.

[0040] Specifically, the guar gum powder mentioned in step two, as a molding aid, can improve the catalyst preparation speed and the surface smoothness of the catalyst during the molding process.

[0041] Further, in step two, the mass ratio of aluminum source II, acid source, encapsulated copper silica-alumina molecular sieve, guar gum powder, additive II, pore-forming agent, and H2O is (5-20):(0-5):(30-50):(0.5-5):(0-5):(0.01-3):(35-55);

[0042] The preferred ratio is (7~17):(0.01~3):(32~46):(0.8~4):(0.3~4):(0.02~2):(38~50);

[0043] Further preferred ratios are (8-15):(0.05-2):(35-44):(1.1-3.6):(0.5-3.4):(0.05-1.4):(40-48).

[0044] Specifically, in step two, the calcination temperature is 400–850℃, and the calcination time is 1–6 hours; preferably, the calcination temperature is 500–650℃, and the calcination time is 2–4 hours. To further improve the performance of the bifunctional molecular sieve catalyst, calcination is carried out in a steam atmosphere. The steam atmosphere preferably has a water vapor volume fraction of 30–80%, more preferably 50%. The alkali source, alkaloids, and pore-forming agents in the raw material are removed by calcination, and the calcination temperature needs to reach the decomposition temperature of the alkali source and alkaloids.

[0045] Specifically, the reduction temperature in step two is 180–260°C, and the reduction time is 7–66 h. The reduction reaction is carried out in an atmosphere with a H2 volume fraction of 10–20%. During the reduction process, CuO encapsulated within the aluminosilicate molecular sieve is reduced to Cu, thus preparing a Cu-Si-Al bifunctional catalyst containing encapsulated copper within the aluminosilicate molecular sieve.

[0046] The Cu-Si-Al bifunctional catalyst provided by this invention has its performance in catalyzing the direct synthesis of cyclic ketones and cyclic enones from cyclic olefins influenced by the content of copper, Lewis acid centers, and Bronsted acid centers in the catalyst material. Furthermore, another important factor affecting the catalyst's performance is the amount of Lewis acid, the amount of Bronsted acid, the specific surface area, and the pore volume within the catalyst.

[0047] A third aspect of the present invention also provides a method for the direct preparation of cyclic ketones and cyclic enones from cyclic olefins, the method using one of the Cu-Si-Al bifunctional catalysts described above.

[0048] Specifically, the method for directly preparing cyclic ketones and cyclic enones from cyclic olefins is as follows:

[0049] The reaction was carried out at temperatures of 100–400 °C, reaction pressures of 0.1–5 MPa, and cyclic olefin mass hourly space velocities of 0.1–94 h⁻¹. -1 Under certain conditions, cyclic olefins are mixed with water at a molar ratio of 1:(0.1–50), and a catalytic reaction is carried out in the presence of the Cu-Si-Al bifunctional catalyst, and the product is recovered.

[0050] Furthermore, the method for directly preparing cyclic ketones and cyclic enones from cyclic olefins includes the following steps:

[0051] The reaction was carried out at temperatures of 100–400 °C, reaction pressures of 0.1–5 MPa, and cyclic olefin mass hourly space velocities of 0.1–94 h⁻¹. -1 Under certain conditions, cyclic olefins are mixed with water at a molar ratio of 1:(0.1-50), and then contacted with the Cu-Si-Al bifunctional catalyst to carry out a catalytic reaction. The resulting reaction material is condensed and then separated into water and oil. The aqueous phase enters the reaction cycle, and the oil phase is separated to obtain the reaction raw material cyclic olefins, the reaction products cyclic ketones and cyclic enones, wherein the cyclic olefins enter the reaction cycle.

[0052] In the method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, the preferred reaction temperature is 130–350 °C, the preferred reaction pressure is 0.5–2.6 MPa, and the preferred olefin mass hourly space velocity is 0.1–40 h⁻¹. -1The molar ratio of cyclic olefin to water is 1:(2-30); further preferred reactions are a reaction temperature of 160-300℃, a reaction pressure of 0.9-2.0 MPa, and a mass hourly space velocity (HHSV) of the cyclic olefin of 0.2-20 h⁻¹. -1 The molar ratio of cyclic olefins to water is 1:(3-15).

[0053] In the preparation process of the Cu-Si-Al bifunctional catalyst provided by this invention, the product is synthesized through a hydrothermal reaction in an alkaline environment under the presence of alkaloid compounds. After calcination, a silica-alumina molecular sieve encapsulating copper oxide is obtained. The alkaloid compounds, through the interaction of hydroxyl and amino functional groups in their molecules with other raw materials, not only guide the formation of a specific crystal structure but also act as fillers to form a secondary porous structure, thereby improving the activity of the silica-alumina molecular sieve. In step two, aluminum source II is dissolved by an acid source and then calcined to form an amorphous aluminum gel. This amorphous aluminum gel, together with the silica-alumina molecular sieve obtained in step one, serves as the main structure of the bifunctional catalyst. After molding, the bifunctional catalyst is given a specific shape and a certain strength to ensure its stability during long-term use and to prevent excessive resistance during material passage through the catalyst bed. Furthermore, the removal of the pore-forming agent by calcination gives the amorphous aluminum gel, serving as the bifunctional catalyst support, a porous structure, further increasing the specific surface area of ​​the bifunctional catalyst and improving catalytic efficiency. Cu-Si-Al bifunctional catalysts containing encapsulated copper-encapsulated silicon-aluminum molecular sieves are applied to the reaction coupling of cyclic olefin hydration and alcohol dehydrogenation, especially in the direct conversion of cyclohexene to cyclohexanone and cycloenone, exhibiting high catalytic activity and selectivity.

[0054] This invention solves the problem of coupled olefin hydration and secondary alcohol dehydrogenation reactions in the preparation of cyclic ketones and cyclic enones from cyclic olefins. It allows for the direct preparation of cyclic ketones and cyclic enones at the same reaction temperature, simplifying the process. Compared to existing olefin-to-ketone technologies, this invention uses a Cu-Si-Al bifunctional catalyst to catalyze the preparation of cyclic ketones and cyclic enones from cyclic olefins, increasing the conversion rate of cyclic olefins from 10% to over 20%, with a cyclic ketone selectivity of over 50%. Furthermore, the selectivity of the cyclic ketones and cyclic enones can be adjusted according to specific raw material ratios and reaction conditions. This invention improves the effective utilization rate of cyclic olefins and the production efficiency of cyclic ketones and cyclic enones while ensuring high product selectivity, reducing the recycling energy consumption of the cyclic olefin substrate and making the production process more economical. Moreover, compared to the existing method of preparing cyclohexenones by chromium oxide catalysis of cyclohexene oxidation using this invention, the method provided by this invention is safer and more efficient, and the product separation is simpler and more efficient. Detailed Implementation

[0055] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0056] The present invention will be described in detail below through specific embodiments. In the following embodiments and comparative examples, the crystal phase diagrams obtained by X-ray diffraction (XRD) were determined using a Philips Panalytical X'pert, under the following test conditions: Cu target, Kα radiation, Ni filter, high-energy detector, tube voltage 30 kV, and tube current 40 mA; the morphology and size of the molecular sieve were determined using a Hitachi S4800 scanning electron microscope with an accelerating voltage of 20 kV; the specific surface area and pore volume of the molecular sieve were tested using the nitrogen adsorption method, and the nitrogen adsorption-desorption curves were measured using a Micromeritics Tristar II 3020-M specific surface area analyzer. The specific surface area and pore volume were calculated using the BET and t-plot methods, and the specific data are shown in Table 4; the acid content was analyzed using a BIQ-RADFTS 3000 Fourier transform infrared spectrometer, and the specific data are shown in Table 4; the distribution of copper was analyzed using a transmission electron microscope.

[0057] In the following examples and comparative examples, the specific results of conversion rate and target product selectivity are shown in Table 4, and the corresponding calculation formulas are as follows:

[0058]

[0059]

[0060] Example 1

[0061] In the presence of an aqueous solvent, aluminum source I (boehmite) and alkali source tetrapropylammonium hydroxide were mixed uniformly in a certain proportion and hydrothermally treated at 100°C for 12 hours to obtain solution 1. Copper source copper nitrate, auxiliary agent I silver nitrate, and dispersant propylenediamine were mixed in a certain proportion to form a uniform and transparent solution 2. Solution 1 and solution 2 were mixed, and then silica gel and alkaloid compounds (a mixture of tryptamine and leonurine in a molar ratio of 1:1) were added in a certain proportion to obtain a mixed system. The molar ratio of silicon source, aluminum source I, copper source, auxiliary agent I, dispersant, alkaloid compounds, alkali source, and H2O in the mixed system was 1:0.01:0.02:0.007:0.08:0.1:0.18:15.

[0062] After transferring the mixture to a reactor, it was subjected to hydrothermal treatment, first at 160℃ for 18 hours, and then at 95℃ for 44 hours. The resulting solid was then dried at 110℃ for 12 hours to obtain a silica-alumina molecular sieve encapsulating copper oxide. In the presence of an aqueous solvent, high-purity boehmite (aluminum source II), nitric acid (acid source), silicon-aluminum molecular sieve particles containing encapsulated copper oxide, guar gum powder, potassium nitrate (auxiliary agent II), methylcellulose (porogen), and H2O were mixed in a mass ratio of 12.3:0.6:36.7:1.3:0.9:0.4:47.8 and uniformly mixed in a kneader to obtain a catalyst precursor. The catalyst precursor was added to an extruder for extrusion to obtain a cylindrical catalyst. After drying, it was calcined at 550℃ for 3 hours. 2 g of the catalyst was weighed and loaded into the reaction tube of a fixed-bed reactor. The catalyst was reduced at 210℃ and with an H2 concentration of 10% for 6 hours to prepare a Cu-Si-Al bifunctional catalyst.

[0063] This embodiment also provides a method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, the method comprising the following steps:

[0064] The fixed-bed reactor was further heated to 250°C, and the system pressure was increased to 1.4 MPa under anaerobic conditions. Cyclohexene and water were introduced into the fixed-bed reactor at a molar ratio of 1:5 for cyclohexene and H₂O, and the reactor was contacted with a Cu-Si-Al bifunctional catalyst. The mass hourly space velocity (HSV) of cyclohexene was 1.5 h⁻¹. -1 The prepared reactants are condensed and then subjected to water-oil separation. The aqueous phase enters the reaction cycle, while the oil phase is fractionated to obtain the reactants cyclohexene, cyclohexanone, and cyclohexenone. The cyclohexene then enters the reaction cycle.

[0065] As another implementation, after the above-mentioned reaction for the direct preparation of cyclic ketones and cyclic enones from cyclic olefins is completed, the Cu-Si-Al bifunctional catalyst packed in the reaction tube of the fixed-bed reactor can be stored in nitrogen or reduced and reused in the reaction for the direct preparation of ketones from olefins, thereby realizing the recycling of the bifunctional catalyst.

[0066] Example 2

[0067] In the presence of an aqueous solvent, aluminum source I (boehmite) and alkali source tetrapropylammonium hydroxide were mixed uniformly in a certain proportion and hydrothermally treated at 100°C for 12 hours to obtain solution 1. Copper source copper nitrate, auxiliary agent I chloroauric acid, and dispersant ethylenediamine were mixed in a certain proportion to form a uniform and transparent solution 2. Solution 1 and solution 2 were mixed, and then silicon source tetraethyl orthosilicate and alkaloid compound (a mixture of tryptamine and leonurine in a molar ratio of 1:1) were added in a certain proportion to obtain a mixed system. The molar ratio of silicon source, aluminum source I, copper source, auxiliary agent I, dispersant, alkaloid compound, alkali source, and H2O in the mixed system was 1:0.01:0.05:0.01:0.12:0.1:0.25:15.

[0068] After transferring the mixture to a reactor, it was subjected to hydrothermal treatment, first at 170℃ for 16 hours, and then at 105℃ for 36 hours. The resulting solid was then dried at 110℃ for 12 hours to obtain aluminosilicate molecular sieve encapsulated with copper oxide. In the presence of an aqueous solvent, aluminum source II (boehmite), acid source nitric acid, prepared silicon-aluminum molecular sieve particles encapsulated with copper oxide, guar gum powder, auxiliary agent II (sodium nitrate), pore-forming agent lignin, and H2O were mixed in a mass ratio of 8.1:0.4:41.4:1.1:0.7:0.8:47.9 and uniformly mixed in a kneader to obtain a catalyst precursor. The catalyst precursor was added to an extruder for extrusion to obtain a honeycomb-shaped porous cylindrical catalyst. After drying, it was calcined at 650℃ for 1 hour. 2 g of the catalyst was weighed and loaded into the reaction tube of a fixed-bed reactor. The catalyst was reduced at 210℃ and with an H2 concentration of 10% for 6 hours to prepare a Cu-Si-Al bifunctional catalyst.

[0069] This embodiment also provides a method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, the method comprising the following steps:

[0070] The fixed-bed reactor was further heated to 280°C, and the system pressure was increased to 2 MPa under anaerobic conditions. Cyclohexene and water were introduced into the fixed-bed reactor at a molar ratio of 1:5 to H₂O, and the reactor was contacted with a Cu-Si-Al bifunctional catalyst. The mass hourly space velocity (HSV) of cyclohexene was 1 h⁻¹. -1 The prepared reactants are condensed and then subjected to water-oil separation. The aqueous phase enters the reaction cycle, while the oil phase is fractionated to obtain the reactants cyclohexene, cyclohexanone, and cyclohexenone. The cyclohexene then enters the reaction cycle.

[0071] As another implementation, after the above-mentioned reaction for the direct preparation of cyclic ketones and cyclic enones from cyclic olefins is completed, the Cu-Si-Al bifunctional catalyst packed in the reaction tube of the fixed-bed reactor can be stored in nitrogen or reduced and reused in the reaction for the direct preparation of ketones from olefins, thereby realizing the recycling of the bifunctional catalyst.

[0072] Example 3

[0073] In the presence of an aqueous solvent, aluminum source I (boehmite) and alkali source tetrapropylammonium hydroxide were mixed uniformly in a certain proportion and hydrothermally treated at 100°C for 12 hours to obtain solution 1. Copper source copper nitrate, auxiliary agent I silver nitrate, and dispersant hexamethylenediamine were mixed in a certain proportion to form a uniform and transparent solution 2. Solution 1 and solution 2 were mixed, and then silicon source tetraethyl orthosilicate and alkaloid compounds (a mixture of tryptamine and leonurine in a molar ratio of 1:1) were added in a certain proportion to obtain a mixed system. The molar ratio of silicon source, aluminum source I, copper source, auxiliary agent I, dispersant, alkaloid compounds, alkali source, and H2O in the mixed system was 1:0.02:0.03:0.02:0.1:0.2:0.25:15.

[0074] After transferring the mixture to a reactor, it was subjected to hydrothermal treatment, first at 180℃ for 14 hours, and then at 110℃ for 30 hours. The resulting solid was then dried at 110℃ for 12 hours to obtain aluminosilicate molecular sieve encapsulated with copper oxide. In the presence of an aqueous solvent, aluminum source II aluminum sol, acid source nitric acid, prepared silicon-aluminum molecular sieve particles encapsulated with copper oxide, guar gum powder, strontium nitrate additive II, corn starch pore-forming agent, and H2O were mixed in a mass ratio of 14.9:0.05:35.0:2.0:1.7:1.4:44.95 and uniformly mixed in a kneader to obtain a catalyst precursor. The catalyst precursor was added to a tablet press for tableting to obtain a tablet catalyst. After drying, it was calcined at 600℃ for 2 hours. 2 g of the tablet was weighed and loaded into the reaction tube of a fixed-bed reactor. The tablet was reduced at 210℃ and H2 concentration of 10% for 6 hours to prepare a Cu-Si-Al bifunctional catalyst.

[0075] This embodiment also provides a method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, the method comprising the following steps:

[0076] The fixed-bed reactor was further heated to 200°C, and the system pressure was increased to 1 MPa under anaerobic conditions. Cyclohexene and water were introduced into the fixed-bed reactor at a molar ratio of 1:5 for cyclohexene and H₂O, and the reactor was contacted with a Cu-Si-Al bifunctional catalyst. The mass hourly space velocity (WHSV) of cyclohexene was 0.6 h⁻¹. -1 The prepared reactants are condensed and then subjected to water-oil separation. The aqueous phase enters the reaction cycle, while the oil phase is fractionated to obtain the reactants cyclohexene, cyclohexanone, and cyclohexenone. The cyclohexene then enters the reaction cycle.

[0077] As another implementation, after the above-mentioned reaction for the direct preparation of cyclic ketones and cyclic enones from cyclic olefins is completed, the Cu-Si-Al bifunctional catalyst packed in the reaction tube of the fixed-bed reactor can be stored in nitrogen or reduced and reused in the reaction for the direct preparation of ketones from olefins, thereby realizing the recycling of the bifunctional catalyst.

[0078] Examples 4-6

[0079] Examples 4-6 provide a cylindrical Cu-Si-Al bifunctional catalyst and its preparation method, as well as a method for preparing cyclic ketones and cyclic enones from cyclic olefins. Compared with Example 1, the preparation steps of Examples 4-6 are the same, but the raw materials and proportions are different, and some preparation conditions are different, as detailed in Table 1.

[0080] Examples 7-10

[0081] Examples 7-10 provide a cylindrical Cu-Si-Al bifunctional catalyst and its preparation method, as well as a method for preparing cyclic ketones and cyclic enones from cyclic olefins. Compared with Example 1, the preparation steps of Examples 7-10 are the same, but the raw materials and proportions are different, and some preparation conditions are different, as detailed in Table 2.

[0082] Examples 11-14

[0083] Examples 11-14 provide a cylindrical Cu-Si-Al bifunctional catalyst, its preparation method, and a method for the direct preparation of ketones from olefins. Compared with Example 1, the preparation steps of Examples 11-14 are the same, but the raw materials and their proportions are different, and some preparation conditions are different, as detailed in Table 3.

[0084] Table 1 Examples 4-6

[0085]

[0086] Table 2 Examples 7-10

[0087]

[0088] Table 3 Examples 11-14

[0089]

[0090] Table 4. Structure and catalytic effect of Cu-Si-Al bifunctional catalysts

[0091]

[0092] The Cu-Si-Al bifunctional catalyst provided by this invention has its performance in preparing cyclic ketones and cyclic enones from cyclic olefins influenced by the content of dehydrogenation active centers, Lewis acid centers, and Bronsted acid centers in the catalytic material. Furthermore, another important factor affecting the catalytic performance of this molecular sieve is the amount of Lewis acid, the amount of Bronsted acid, the specific surface area, and the pore volume within the molecular sieve. Referring to Table 4 and Examples 6-9, it can be seen that when the specific surface area is ≤129 m²... 2 / g, pore volume ≤0.16cm³ 3 When the Lewis acid concentration is ≤16.9 μmol / g and the Bronsted acid concentration is ≤2.9 μmol / g, the catalytic effect of the corresponding Cu-Si-Al bifunctional catalyst will be affected to some extent, but the selectivity of the cyclic ketone product will still be higher than 65%. Referring to Table 4 and Examples 11-14, it can be seen that when the Lewis acid concentration is ≤16.9 μmol / g and the Bronsted acid concentration is ≤2.9 μmol / g, the catalytic effect of the corresponding Cu-Si-Al bifunctional catalyst will also be affected to some extent. Therefore, the Lewis acid concentration of the Cu-Si-Al bifunctional catalyst is 10.7–237.4 μmol / g, preferably 16.9–194.8 μmol / g; the Bronsted acid concentration is 1.3–46.9 μmol / g, preferably 2.9–36.7 μmol / g.

[0093] This invention simplifies the process by addressing the coupling problem of olefin hydration and secondary alcohol dehydrogenation reactions in the preparation of cyclic ketones and cyclic enones from cyclic olefins, allowing for the direct preparation of cyclic ketones and cyclic enones at the same reaction temperature. The method using a Cu-Si-Al bifunctional catalyst to catalyze the preparation of cyclic ketones and cyclic enones from cyclic olefins increases the conversion rate of cyclic olefins from 10% to over 35% compared to existing olefin-to-ketone technologies, while achieving a selectivity of over 85% for the cyclic ketones and cyclic enones. Furthermore, the selectivity of the cyclic ketones and cyclic enones can be adjusted according to specific feedstock ratios and reaction conditions. While ensuring high product selectivity, this invention improves the effective utilization rate of cyclic olefins, the production efficiency of cyclic ketones and cyclic enones, and reduces the recycling energy consumption of the cyclic olefin substrate, making the production process more economical. Compared to the existing method of cyclohexene oxidation to prepare cyclohexenone, the method provided by this invention is safer and more efficient, and product separation is simpler and more efficient.

[0094] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing a Cu-Si-Al bifunctional catalyst, characterized in that, The Cu-Si-Al bifunctional catalyst comprises a support and an active component; the support is an amorphous aluminum gel, and the active component is a copper-encapsulated silica-alumina molecular sieve; the copper provides dehydrogenation active centers for the Cu-Si-Al bifunctional catalyst; the support and the silica-alumina molecular sieve provide Lewis acid centers and Bronsted acid centers for the Cu-Si-Al bifunctional catalyst; the Lewis acid centers have an acidity of 10.7~237.4 μmol / g, and the Bronsted acid centers have an acidity of 1.3~46.9 μmol / g; The preparation method of the Cu-Si-Al bifunctional catalyst includes the following steps: Step 1: Mix silicon source, aluminum source I, copper source, additive I, dispersant, alkaloid compound, alkali source, and H2O in a certain proportion to obtain a mixed system; perform hydrothermal treatment on the mixed system at 50~190℃ for 3~10 days, and then filter and dry to obtain silicon-aluminum molecular sieve encapsulated with copper oxide. Step 2: Mix aluminum source II, acid source, the encapsulated copper oxide silica-alumina molecular sieve obtained in Step 1, guar gum powder, additive II, pore-forming agent, and H2O in a certain proportion to prepare a catalyst precursor; shape the catalyst precursor, dry it, calcine it at 400~850℃ for 1~6h, and reduce it in H2 atmosphere at 160~300℃ for 12~72h to obtain a Cu-Si-Al bifunctional catalyst containing encapsulated copper silica-alumina molecular sieve; In step one: The alkaloid compound is a mixture of tryptophan and leonurine, wherein the molar ratio of tryptophan to leonurine in the mixture is (0.1~10):1; or, the alkaloid compound is a mixture of tryptophan and tryptophan, wherein the molar ratio of tryptophan to tryptophan in the mixture is 1:1; or, the alkaloid compound is a mixture of 5-hydroxytryptamine and leonurine, wherein the molar ratio of 5-hydroxytryptamine to leonurine in the mixture is 1:1; or, the alkaloid compound is a mixture of tryptophan and ephedrine, wherein the molar ratio of tryptophan to ephedrine in the mixture is 3:

1. The auxiliary agent I is selected from any one of silver nitrate, nickel nitrate, zinc nitrate, chloroauric acid, chloroplatinic acid, and palladium chloride; The dispersant is selected from at least one of ethylamine, ethylenediamine, propylenediamine, hexamethylenediamine, aniline, pyridine, thiophene, thiol, thiophenol, and thioether; The alkali source is selected from at least one of tetraethylammonium hydroxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

2. The preparation method according to claim 1, characterized in that, In step one: The silicon source is selected from at least one of organosilicone esters, silica gel, fumed silica, and silica sol; The aluminum source I is selected from at least one of aluminum nitrate, aluminum chloride, aluminum hydroxide, boehmite, acidic aluminum sol, and basic aluminum sol. The copper source is selected from at least one of copper nitrate, copper chloride, tetraphenylporphyrin copper, and copper acetylacetonate.

3. The preparation method according to claim 1, characterized in that, In step one, the molar ratio of silicon source, aluminum source I, copper source, additive I, dispersant, alkaloid compound, alkali source, and H2O is 1:(0.005~0.2):(0.005~0.4):(0.001~0.08):(0.05~1.6):(0.08~2.2):(0.15~3):(10~200); the silicon source is SiO2, and the alkali source is N or OH. - count.

4. The preparation method according to claim 1, characterized in that, In step two: The aluminum source II is selected from at least one of boehmite, aluminum hydroxide, and aluminum sol. The acid source is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, adipic acid, acetic acid, isononanoic acid, and isovaleric acid; The auxiliary agent II is selected from those containing Na. + K + 、Rb + Cs + Mg 2+ Ca 2+ Ba 2+ At least one of the compounds containing at least one ion; The pore-forming agent is selected from at least one of starch, cellulose, lignin, or modified compounds of starch / cellulose / lignin.

5. The preparation method according to claim 1, characterized in that, In step two, the mass ratio of aluminum source II, acid source, silicon-aluminum molecular sieve encapsulating copper oxide, guar gum powder, additive II, pore-forming agent, and H2O is (5~20):(0~5):(30~50):(0.5~5):(0~5):(0.01~3):(35~55).

6. A method for directly preparing cyclic ketones and cyclic enones from cyclic olefins, characterized in that, The method uses the Cu-Si-Al bifunctional catalyst prepared by any one of the preparation methods described in claims 1 to 5.

7. The method for directly preparing cyclic ketones and cyclic enones from cyclic olefins according to claim 6, characterized in that, The method is as follows: the reaction temperature is 100~400℃, the reaction pressure is 0.1~5MPa, and the mass hourly space velocity of the cyclic olefin is 0.1~94h. -1 Under certain conditions, cyclic olefins are mixed with water at a molar ratio of 1:(0.1~50), and a catalytic reaction is carried out in the presence of the Cu-Si-Al bifunctional catalyst, and the product is recovered.

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