A composite catalyst and its preparation method and application
By using a composite catalyst composed of active metal salt, support and chiral cyclopentadiene ligand, the high cost and difficulty of separation in the preparation of geraniol by citral hydrogenation is solved, and high-purity and low-cost geraniol are achieved. Alcohol preparation has good industrial prospects.
Patent Information
- Application Number
- CN202411355932.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2044-09-27
AI Technical Summary
The existing methods for preparing geraniol with citral hydrogenation have high cost, complex processes, harsh catalytic conditions and difficult to obtain a single product with high purity, especially because the boiling points of neroliol and geraniol are close, and the separation process consumes high energy. And the product is easily oxidized.
A composite catalyst is used, which consists of active metal salts, support and ligands with chiral cyclopentadiene backbone to form a highly active and highly selective catalytic system that can efficiently catalyze citral into fragrance under mild conditions. Iron, avoids the generation of by-products and achieves the high purity preparation of geraniol through stereoselective control of specific structures.
It has achieved the preparation of geraniol with low cost, simple process, high purity of product and pure aroma, with a conversion rate of 99.86%, a selectivity of 99.82%. After continuous application, the conversion rate and selectivity have only slightly decreased. It is suitable for industrial applications. .
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Figure CN118874549B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of selective hydrogenation catalysts, and in particular to a composite catalyst and a preparation method and application thereof. Background Art
[0002] Citral (3,7-dimethyl-2,6-octadienal) has two cis and trans isomers and is an important open-chain monoterpene aldehyde. As an important raw material for spices and pharmaceutical intermediates, citral has many types of reaction products obtained by selective hydrogenation, mainly including nerol, geraniol, citronellol and citronellal, etc. These compounds have important application value. Among them, geraniol (trans-3,7-dimethyl-2,6-octadien-1-ol) is the trans isomer of nerol. Natural geraniol exists in more than 50 plants such as Pelargonium of the genus Geraniaceae, Rue of the genus Cymbopogon of the genus Graminaceae, and Litsea cubeba of the fruit of Litsea cubeba of the genus .... It is widely used in the fields of medicine, tobacco, food ingredients, etc. The smell of geraniol is the smell of blooming roses. It is the main sweetener in the perfume industry and the main component of false rose essential oil.
[0003] Geraniol has outstanding characteristics and its antimicrobial ability is the best among all monoterpene alcohols. Therefore, trans-geraniol (i.e. geraniol) is very effective for viral skin herpes. Geraniol is usually obtained by selective hydrogenation of citral. Citral is a typical α, β-unsaturated aldehyde. The product of its selective hydrogenation is a mixture of geraniol and nerol, and it also contains perhydrogenated products citronellol and tetrahydrogeraniol. Not only can a single, high-purity product not be obtained, but it also affects the aroma of the product. Nerol and geraniol are cis-trans isomers with relatively close boiling points. The two are difficult to separate. Usually, high-efficiency distillation columns are required for multiple distillations to obtain high-purity products with qualified aroma. This separation process has problems such as high energy consumption, cumbersome steps, high cost, and the product is easily oxidized in the air.
[0004] In addition, most reports on the preparation of geraniol by hydrogenation of citral use a supported catalyst for hydrogenation. The active centers in the existing catalytic methods are concentrated on non-precious metals such as Ni and Co and precious metals such as Ru, Pt and Os. Although good conversion rates and selectivity can be achieved, there are still defects such as high production costs, complicated preparation methods, and harsh catalytic conditions.
[0005] Therefore, it is of great significance to design a catalyst with low cost, good catalytic activity, mild reaction conditions and high product purity, and apply it to catalyze the reaction of citral to obtain a single product, geraniol. Summary of the invention
[0006] In order to solve the above technical problems, the present invention provides a composite catalyst and a preparation method and application thereof. The composite catalyst provided by the present invention has low preparation cost and good catalytic activity, can selectively hydrogenate citral to obtain a single geraniol product with high selectivity, and has no over-hydrogenation product generation, and has the advantages of simple process, high selectivity, high product purity, pure aroma, and not easy to oxidize.
[0007] To achieve this object, the present invention adopts the following technical solutions:
[0008] In a first aspect, the present invention provides a composite catalyst, which comprises an active metal salt, a carrier and a ligand; the ligand has a chiral cyclopentadiene skeleton.
[0009] In the present invention, the active metal salt, the carrier and the ligand with a chiral cyclopentadiene skeleton form a specific catalytic system, which play a synergistic role together, so that the obtained composite catalyst has high activity, high stability and high selectivity. When it is applied to the reaction of preparing geraniol from citral, the generation of by-products can be effectively avoided, so that the single high-purity geraniol product can be obtained by selectively catalyzing and hydrogenating citral better.
[0010] It is worth noting that in the composite catalyst provided by the invention, the specific catalytic system can be efficiently combined with the carbon-oxygen double bond of the carbonyl, and the carbon-carbon double bond hydrogenation activity in citral is weak, so that the carbonyl hydrogenation in the catalytic citral of high selectivity can be suppressed, and the generation of hydrogenation side reaction is suppressed, and then a highly purified geraniol product is obtained. Meanwhile, the stereoselectivity of the chiral cyclopentadiene ligand of specific structure is single, and the "back wall" and "side wall" steric hindrance of vertical space blockade on the ligand are conducive to its chiral control in the catalytic process, and coordinated with active metal, first the nerol of cis structure is isomerized into the geraniol with trans structure, and then selective hydrogenation is carried out, so as to achieve the purpose of efficiently combining with the trans structure geraniol, and then a highly purified geraniol product is obtained simply and efficiently, without the need to carry out the separation of geraniol and nerol, and separation energy consumption is greatly saved. In addition, the use of specific active metal salt reduces production cost, and metal alloy effect can be formed between itself and the carrier, and the activity of the composite catalyst is significantly enhanced, so that the reaction of preparing geraniol from citral can be carried out under milder conditions, and the generation of side reaction is further reduced.
[0011] Preferably, the active metal salt comprises any one of active metal nitrates, chlorides, sulfates, acetates, acetylacetonates or hydrates thereof, or a combination of at least two thereof.
[0012] Preferably, the active metal includes any one of Fe, Ni, Cu, Zn, Mn, Co, Bi, Pb or In, or a combination of at least two thereof.
[0013] In the present invention, a catalytic system composed of active metal salts is selected in the composite catalyst, which avoids the concentration of active centers on non-precious metals such as Ni and Co and precious metals such as Ru, Pt and Os in the catalytic method of the prior art, not only expanding the selection range of active metals, but also reducing production costs, while making the preparation process of the composite catalyst simpler and the catalytic reaction milder, thereby overcoming technical defects such as complicated preparation methods and harsh catalytic conditions.
[0014] Preferably, the carrier is a metal organic framework material.
[0015] Preferably, the metal organic framework material includes any one of MIL-101, MIL-88A, MIL-125, Uio-66, ZIF-8 or ZIF-67, or a combination of at least two thereof.
[0016] Preferably, the ligand includes the compound shown in L1 and / or the compound shown in L2 below;
[0017] .
[0018] Preferably, the amount of active metal atoms in the active metal salt is 1.0%-10% of the mass of the carrier, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., preferably 3.0%-9.0%, and more preferably 3.0%-7.0%.
[0019] In the present invention, the amount of active metal atoms in the carrier and the active metal salt is controlled within a certain range to improve the reaction activity of the composite catalyst, thereby improving the conversion rate of the reaction of preparing geraniol from citral and the selectivity of geraniol. When the amount of active metal atoms in the active metal salt is high, due to the limitation of the catalyst active site, the reaction selectivity and conversion rate are not significantly improved, resulting in a waste of metal raw materials; when the amount of active metal atoms in the active metal salt is low, due to the large reduction in catalyst activity, the reaction conversion rate and selectivity are significantly reduced, affecting the effect of the reaction. Therefore, considering the technical effect of the catalyst and the economic benefits in actual production, when the amount of active metal atoms in the active metal salt is 3.0%-7% of the carrier mass, its production effect is best.
[0020] Preferably, the molar ratio of the ligand to the active metal atoms in the active metal salt is (1-3):1, for example, it can be 1:1, 1.1:1, 1.3:1, 1.5:1, 2:1, 2.2:1, 2.5:1, 2.8:1 or 3:1, etc., preferably (1-2):1, and more preferably (1.1-1.5):1.
[0021] In the present invention, the specific molar ratio of the active metal atoms in the ligand and active metal salt is conducive to improving the reaction activity of the composite catalyst within a certain range, and then is conducive to improving the conversion rate of the reaction of preparing geraniol from citral and the selectivity of geraniol. When the consumption of the ligand is higher, it is impossible to fully combine with the ligand because of the limited site of the active metal, not only the catalyst activity will be affected, but also the waste of the ligand raw material will be caused; When the consumption of the ligand is lower, the ligand number is few and cannot achieve complete coordination with the active metal, resulting in few active sites of the catalyst, affecting the activity of the catalyst. Therefore, considering the economic benefits in the reaction effect of the catalyst and the actual production, when the mol ratio of the active metal atoms in the ligand and active metal salt is (1.1-1.5): 1, its production effect is best.
[0022] In a second aspect, the present invention provides a method for preparing the composite catalyst as described in the first aspect, the preparation method comprising the following steps:
[0023] (1) dissolving an active metal salt in a solvent, adding a ligand, and mixing to obtain a metal complex solution;
[0024] (2) Adding a carrier to the metal complex solution of step (1) for adsorption to obtain the composite catalyst.
[0025] Preferably, the solvent in step (1) comprises water.
[0026] Preferably, the mixing in step (1) is carried out under stirring.
[0027] Preferably, the mixing temperature in step (1) is 40-100°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 70°C, 80°C, 90°C or 100°C.
[0028] Preferably, the mixing time in step (1) is 2-6 h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h.
[0029] Preferably, the adsorption temperature in step (2) is 30-60°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.
[0030] Preferably, the adsorption time in step (2) is 4-8 h, for example, it can be 4 h, 4.2 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h or 8 h.
[0031] Preferably, step (2) further includes a post-treatment step after the adsorption.
[0032] Preferably, the post-treatment step comprises cooling, filtering and drying.
[0033] Preferably, the cooling is cooling to room temperature (20-30°C, for example, 20°C, 22°C, 25°C, 28°C or 30°C).
[0034] Preferably, the drying is vacuum drying.
[0035] Preferably, the vacuum drying temperature is 70-90°C, for example, it can be 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, 88°C or 90°C.
[0036] In a third aspect, the present invention provides a method for preparing geraniol by catalytic hydrogenation of citral, the method comprising: obtaining geraniol by hydrogenation of citral under the catalysis of the composite catalyst described in the first aspect.
[0037] The invention applies a specific composite catalyst to the reaction of preparing geraniol from citral, and can obtain a single high-purity geraniol product by selective hydrogenation of citral with high selectivity. The invention has the advantages of low production cost, simple preparation process, high selectivity, high product purity, good aroma quality and not easy to be oxidized.
[0038] Preferably, the amount of the composite catalyst is 1.0wt%-10.0wt% of the mass of citral, for example, it can be 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt% or 10.0wt%, etc., preferably 3.0wt%-9.0wt%, and more preferably 3.0wt%-7.0wt.
[0039] In the present invention, the specific mass ratio of composite catalyst and citral is conducive to improving the reactivity of composite catalyst, thereby improving the conversion rate of geraniol prepared by citral and the selectivity of geraniol. When the composite catalyst concentration is higher, excessive hydrogenation is caused due to the excessively high local concentration of catalyst, so that the reaction selectivity is reduced; When the composite catalyst concentration is lower, due to the limited number of catalyst active sites, the reaction conversion rate is caused to decrease. In addition, in the actual production process, the excessive amount of catalyst can significantly increase the production cost, thereby reducing the economic benefit of production, and does not meet the needs of large-scale industrial production. Therefore, from the comprehensive consideration of the economic benefit in the reaction effect of the conversion rate of reaction and the selectivity of geraniol and the actual production, when the consumption of the composite catalyst is 3.0wt%-7.0wt% of the mass of citral, it has the best use effect.
[0040] Preferably, the raw material for the hydrogenation reaction also includes hydrogen.
[0041] Preferably, the hydrogenation reaction is carried out in a solvent.
[0042] Preferably, the solvent comprises water or an organic solvent.
[0043] In the present invention, the selective hydrogenation reaction can be carried out in the presence of a solvent or in the absence of a solvent; if the reaction is carried out in the presence of a solvent, the solvent is selected from water or an organic solvent with good dispersion.
[0044] Preferably, the organic solvent includes any one of ethanol, propylene glycol, octanol, propylene carbonate or dioctyl phthalate, or a combination of at least two thereof, preferably ethanol.
[0045] Preferably, the absolute pressure of the hydrogenation reaction is 1-6 MPa, for example, it can be 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa or 6 MPa, etc., preferably 1-4 MPa.
[0046] In the present invention, when the absolute pressure of the hydrogenation reaction is set to 1-4 MPa, the reaction is both safe and efficient.
[0047] Preferably, the temperature of the hydrogenation reaction is 80-120°C, for example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, etc., preferably 80-100°C.
[0048] Preferably, the hydrogenation reaction time is 1-4 h, for example, 1 h, 1.5 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 4 h, etc., preferably 2-4 h.
[0049] The numerical range described in the present invention not only includes the point values listed above, but also includes any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.
[0050] Compared with the prior art, the present invention has at least the following beneficial effects:
[0051] (1) The composite catalyst provided by the present invention has the characteristics of high activity and high stability. It not only has a high conversion rate (can reach 99.86%) and a high selectivity (can reach 99.82%) in the reaction of catalytic hydrogenation of citral to prepare geraniol, but also can be recycled. After 10 consecutive uses, its conversion rate only decreased by 0.15%, and its selectivity only decreased by 0.25%. That is, the composite catalyst of the present invention not only improves production efficiency but also reduces production cost, and has good prospects for industrial application;
[0052] (2) The composite catalyst system formed by the active metal salt, chiral cyclopentadiene ligand and carrier used in the present invention efficiently combines with the carbon-oxygen double bond of the carbonyl group, but has weak hydrogenation activity for the carbon-carbon double bond in citral, thereby catalyzing the hydrogenation of the carbonyl group in citral with high selectivity, inhibiting the occurrence of hydrogenation side reactions, and obtaining a high-purity product with pure aroma;
[0053] (3) The stereoselectivity of the chiral cyclopentadiene ligand with a specific structure in the composite catalyst provided by the present invention is single, and the steric hindrance of the vertical space blocking "back wall" and "side wall" on the ligand is beneficial to its chirality control in the catalytic process. When combined with the active metal, the cis-structured nerol is first isomerized into the trans-structured geranial, and then selectively hydrogenated, thereby achieving the purpose of efficient combination with the trans-structured geranial, and then obtaining a high-purity geraniol product simply and efficiently, without the need to separate geraniol and nerol, which greatly saves separation energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0054] Figure 1 This is the gas chromatogram of the reaction liquid obtained in Application Example 26 of the present invention. DETAILED DESCRIPTION
[0055] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.
[0056] The information of some raw materials used in the following examples, comparative examples, application examples and comparative application examples is as follows:
[0057] Citral ≥ 99.5%, produced by the company, specifications are 60 and 98, that is, the ratio of geranial to neral is 60:40 and 98:2 respectively. If there is no special description, the content is 60:40;
[0058] The CAS number of L1 is 1417714-08-9, and the relative molecular weight is 404.51;
[0059] The CAS number of L2 is 2222463-76-3, and the relative molecular weight is 258.36;
[0060] The CAS number of L3 (cyclopentadiene) is 542-92-7 and the relative molecular weight is 66.1;
[0061] Other raw materials and reagents were commercially available unless otherwise specified.
[0062] The calculation formulas used in the following embodiments, comparative examples, application examples and comparative application examples are as follows:
[0063] (1) Metal loading of the reaction:
[0064] ;
[0065] (2) Amount of metal-loaded ligand used in the reaction:
[0066] ;
[0067] (3) Conversion rate:
[0068] ;
[0069] (4) Reaction selectivity:
[0070] ;
[0071] Among them, the by-products are citronellol and nerol.
[0072] Example 1
[0073] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0074] At room temperature, anhydrous FeCl3 (0.726 g, 4.476 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (2.72 g, 6.714 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-101 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 1.
[0075] Example 2
[0076] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0077] At room temperature, anhydrous FeCl3 (0.726 g, 4.476 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (2.72 g, 6.714 mmol) was added and stirred evenly. The temperature was raised to 100°C and stirred for 2 h. After cooling to 60°C, MIL-101 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 2.
[0078] Example 3
[0079] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0080] At room temperature, anhydrous FeCl3 (0.726 g, 4.476 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (2.72 g, 6.714 mmol) was added and stirred evenly. The temperature was raised to 60°C and stirred for 4 h. After cooling to 40°C, MIL-101 carrier (5 g) was added. After adsorption for 6 hours, the temperature was lowered to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 3.
[0081] Example 4
[0082] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0083] At room temperature, anhydrous FeCl3 (0.726 g, 4.476 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (2.72 g, 6.714 mmol) was added and stirred evenly. The temperature was raised to 40°C and stirred for 4 h. After cooling to 30°C, MIL-101 carrier (5 g) was added and adsorbed for 6 h before being cooled to room temperature. The mixture was filtered and the filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 4.
[0084] Example 5
[0085] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (1.81 g, 4.476 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 5.
[0086] Example 6
[0087] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (1.99 g, 4.924 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 6.
[0088] Example 7
[0089] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (2.35 g, 5.819 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 7.
[0090] Example 8
[0091] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (2.90 g, 7.162 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 8.
[0092] Example 9
[0093] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (3.62 g, 8.953 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 9.
[0094] Example 10
[0095] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (4.53 g, 11.191 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 10.
[0096] Embodiment 11
[0097] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (5.43 g, 13.429 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 11.
[0098] Example 12
[0099] This embodiment provides a composite catalyst, which is different from Example 1 only in that anhydrous FeCl3 (0.726 g, 4.476 mmol) is adjusted to anhydrous FeCl3 (0.145 g, 0.895 mmol), and ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (0.54 g, 1.343 mmol), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, recorded as Catalyst 12.
[0100] Example 13
[0101] This embodiment provides a composite catalyst, which is different from Example 1 only in that anhydrous FeCl3 (0.726 g, 4.476 mmol) is adjusted to anhydrous FeCl3 (0.436 g, 2.686 mmol), and ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (1.63 g, 4.029 mmol), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, recorded as Catalyst 13.
[0102] Embodiment 14
[0103] This embodiment provides a composite catalyst, which is different from Example 1 only in that anhydrous FeCl3 (0.726 g, 4.476 mmol) is adjusted to anhydrous FeCl3 (1.016 g, 6.267 mmol), and ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (3.80 g, 9.40 mmol), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, which is recorded as Catalyst 14.
[0104] Embodiment 15
[0105] This embodiment provides a composite catalyst, which is different from Example 1 only in that anhydrous FeCl3 (0.726 g, 4.476 mmol) is adjusted to anhydrous FeCl3 (1.307 g, 8.057 mmol), and ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (4.89 g, 12.086 mmol), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, recorded as Catalyst 15.
[0106] Example 16
[0107] This embodiment provides a composite catalyst, which is different from Example 1 only in that anhydrous FeCl3 (0.726 g, 4.476 mmol) is adjusted to anhydrous FeCl3 (1.452 g, 8.953 mmol), and ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L1 (5.43 g, 13.429 mmol), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, recorded as Catalyst 16.
[0108] Embodiment 17
[0109] This embodiment provides a composite catalyst, which differs from Embodiment 1 only in that ligand L1 (2.72 g, 6.714 mmol) is adjusted to ligand L2 (1.73 g, 6.714 mmol), and other raw materials, contents and methods are the same as those in Embodiment 1, to obtain a composite catalyst, which is recorded as Catalyst 17.
[0110] Embodiment 18
[0111] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0112] At room temperature, CuSO4·5H2O (1.375 g, 5.507 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L2 (2.13 g, 8.261 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-101 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 18.
[0113] Embodiment 19
[0114] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0115] At room temperature, NiSO4·6H2O (1.568 g, 5.964 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (3.62 g, 8.945 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-88A carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 19.
[0116] Embodiment 20
[0117] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0118] At room temperature, Pb(NO3)2·2H2O (0.450 g, 1.689 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L2 (0.65 g, 2.534 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-125 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 20.
[0119] Embodiment 21
[0120] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0121] At room temperature, Zn(NO3)2·6H2O (1.592 g, 5.351 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (3.25 g, 8.026 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, Uio-66 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 21.
[0122] Embodiment 22
[0123] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0124] At room temperature, MnSO4·H2O (1.077 g, 5.351 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L2 (2.47 g, 9.556 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, ZIF-8 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 22.
[0125] Embodiment 23
[0126] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0127] At room temperature, Co(OAc)2·4H2O (1.479 g, 5.939 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (3.60 g, 8.909 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, ZIF-67 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 23.
[0128] Embodiment 24
[0129] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0130] At room temperature, Bi(NO3)2·5H2O (0.812 g, 1.675 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L2 (0.65 g, 2.512 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-101 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 24.
[0131] Embodiment 25
[0132] This embodiment provides a composite catalyst, and the preparation method thereof comprises the following steps:
[0133] At room temperature, InCl3·4H2O (0.894 g, 3.049 mmol) was added to 20 mL of deionized water and stirred until completely dissolved. Then, ligand L1 (1.85 g, 4.573 mmol) was added and stirred evenly. The temperature was raised to 80°C and stirred for 6 h. After cooling to 40°C, MIL-125 carrier (5 g) was added and adsorbed for 6 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in a vacuum drying oven at 80°C to constant weight to obtain a composite catalyst, which was recorded as catalyst 25.
[0134] Comparative Example 1
[0135] This comparative example provides a composite catalyst, which differs from Example 1 only in that ligand L1 is not added, and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, which is recorded as Comparative Catalyst 1.
[0136] Comparative Example 2
[0137] This comparative example provides a composite catalyst, which differs from Example 1 only in that anhydrous FeCl3 is not added, and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, which is recorded as Comparative Catalyst 2.
[0138] Comparative Example 3
[0139] This comparative example provides a composite catalyst, which differs from Example 1 only in that no MIL-101 carrier is added, and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, which is recorded as Comparative Catalyst 3.
[0140] Comparative Example 4
[0141] This comparative example provides a composite catalyst, which differs from Example 1 only in that ligand L1 is replaced by ligand L3 (cyclopentadiene), and other raw materials, contents and methods are the same as those in Example 1, to obtain a composite catalyst, which is recorded as comparative catalyst 4.
[0142] Application Example 1
[0143] In a 500 mL stainless steel reactor, citral (50 g, 0.328 mol), ethanol (50 g), and catalyst 1 (2.5 g) were added in sequence, the autoclave was sealed, and nitrogen and hydrogen were used for replacement 3 times each, and hydrogen was filled to 4.0 Mpa, stirring and heating were started, and the selective hydrogenation reaction temperature was controlled to be 100°C. The hydrogen pressure was maintained at 4.0 Mpa by supplementation, and selective hydrogenation was carried out, and the reaction was kept warm for 4 h. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC.
[0144] Application Example 2
[0145] In a 500 mL stainless steel reactor, citral (50 g, 0.328 mol) and catalyst 1 (2.5 g) were added in sequence, the autoclave was sealed, nitrogen and hydrogen were used for replacement 3 times, hydrogen was filled to 6.0 Mpa, stirring and heating were started, the selective hydrogenation reaction temperature was controlled to 100 °C, the hydrogen pressure was maintained at 6.0 Mpa by supplementation, selective hydrogenation was carried out, and the reaction was kept warm for 2 hours. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC.
[0146] Application Example 3
[0147] In a 500 mL stainless steel reactor, citral (50 g, 0.328 mol), deionized water (50 g), and catalyst 1 (2.5 g) were added in sequence, the autoclave was sealed, and nitrogen and hydrogen were used for replacement 3 times each, and hydrogen was filled to 4.0 Mpa, stirring and heating were started, and the selective hydrogenation reaction temperature was controlled to 120°C. The hydrogen pressure was maintained at 4.0 Mpa by supplementation, and selective hydrogenation was carried out, and the reaction was kept warm for 4 h. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC.
[0148] Application Example 4
[0149] In a 500 mL stainless steel reactor, citral (50 g, 0.328 mol), ethanol (50 g), and catalyst 1 (2.5 g) were added in sequence, the autoclave was sealed, and nitrogen and hydrogen were used for replacement 3 times each, and hydrogen was filled to 4.0 Mpa, stirring and heating were started, and the selective hydrogenation reaction temperature was controlled to 80°C. The hydrogen pressure was maintained at 4.0 Mpa by supplementation, and selective hydrogenation was carried out, and the reaction was kept warm for 4 h. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC.
[0150] Application Example 5
[0151] In a 500 mL stainless steel reactor, citral (50 g, 0.328 mol), ethanol (50 g), and catalyst 1 (2.5 g) were added in sequence, the autoclave was sealed, and nitrogen and hydrogen were used for replacement 3 times each, and hydrogen was filled to 4.0 Mpa, stirring and heating were started, and the selective hydrogenation reaction temperature was controlled to 120°C. The hydrogen pressure was maintained at 4.0 Mpa by supplementation, and selective hydrogenation was carried out, and the reaction was kept warm for 2 h. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC.
[0152] Application Example 6
[0153] The only difference between this application example and application example 1 is that catalyst 1 (2.5 g) is adjusted to catalyst 1 (0.5 g), and other raw materials, amounts and methods are the same as those in application example 1.
[0154] Application Example 7
[0155] The only difference between this application example and application example 1 is that catalyst 1 (2.5 g) is adjusted to catalyst 1 (1.5 g), and other raw materials, amounts and methods are the same as those in application example 1.
[0156] Application Example 8
[0157] The only difference between this application example and application example 1 is that catalyst 1 (2.5 g) is adjusted to catalyst 1 (3.5 g), and other raw materials, amounts and methods are the same as those in application example 1.
[0158] Application Example 9
[0159] The only difference between this application example and application example 1 is that catalyst 1 (2.5 g) is adjusted to catalyst 1 (4.5 g), and other raw materials, amounts and methods are the same as those in application example 1.
[0160] Application Example 10
[0161] The difference between this application example and application example 1 is that catalyst 1 (2.5 g) is adjusted to catalyst 1 (5 g), and the other raw materials, amounts and methods are the same as those in application example 1. The analysis results of the conversion rate and geraniol selectivity of application examples 1-10 are shown in Table 1.
[0162] Table 1
[0163]
[0164] It can be seen from Application Examples 1 and 6-10 in Table 1 that when the specific composite catalyst provided by the present invention is used for the selective catalytic hydrogenation of citral to prepare geraniol, its specific mass ratio with citral can improve the conversion rate of the reaction and the selectivity of geraniol within a certain range. When the amount of the composite catalyst is 7.0wt% of the mass of citral, the conversion rate can reach 99.86%, the selectivity can reach 99.82%, and the over-hydrogenation product tetrahydrogeraniol and other by-products are not detected, and the product aroma is pure; when the amount of the composite catalyst is higher than 7.0wt% of the mass of citral, although the conversion rate is slightly increased, the selectivity will decrease. In addition, in actual production, from the perspective of comprehensive consideration of actual reaction effect and economic benefit, the composite catalyst has the best use effect when the content is 3-7% of the mass of citral.
[0165] Application Examples 11-34 and Comparative Application Examples 1-4 only changed the type of catalyst, and other raw materials, contents and methods were the same as those in Application Example 1. The corresponding analysis results are shown in Table 2.
[0166] Table 2
[0167]
[0168] Application Example 35
[0169] In a 500mL stainless steel reactor, citral (geranial: neral 98:2, 50g, 0.328mol), ethanol (50g), and catalyst 1 (2.5g, mass concentration 5%) were added in sequence, the autoclave was sealed, and nitrogen and hydrogen were used for replacement 3 times each, and hydrogen was filled to 4.0Mpa, stirring and heating were started, and the selective hydrogenation reaction temperature was controlled to 100°C. The hydrogen pressure was maintained at 4.0Mpa by supplementation, and selective hydrogenation was carried out, and the reaction was kept warm for 2h. The reaction liquid was cooled to room temperature, the pressure was released, and the reaction liquid was sampled and analyzed by GC, with a conversion rate of 99.90% and a geraniol selectivity of 100%.
[0170] Through the specific selection of citral, the specific composite catalyst of the present invention is applied to the selective hydrogenation of citral to prepare geraniol, which can achieve excellent results of a conversion rate of 99.90% and a selectivity of 100%.
[0171] Combining Table 1 and Table 2, we can see that:
[0172] (1) The composite catalyst provided by the present invention has high activity and can selectively catalyze hydrogenation of citral under relatively mild and safe conditions to obtain a single geraniol product, with a product yield and selectivity both higher than 97%. The product yield and selectivity can be further improved by specifically selecting the type and dosage of the catalyst, so that the conversion rate can reach 99.86% and the selectivity can reach 99.82%;
[0173] (2) The comparison between Application Example 1 and Application Examples 14-20 of the present invention shows that when the specific molar ratio of the ligand to the active metal atom in the active metal salt is within a certain range, the reaction conversion rate and the selectivity of geraniol can be improved. When the molar ratio of the two is lower than 1.1:1, the active metal and the ligand cannot be fully combined, resulting in a decrease in the activity of the catalyst; when the molar ratio of the two is higher than 1.5:1, at this time, as the ligand content increases significantly, the conversion rate and selectivity of the reaction increase, but the increase is not obvious. From the perspective of reaction effect and economic cost, it is not conducive to improving the comprehensive benefits in actual production. Therefore, when the molar ratio of the two is (1.1-1.5):1, the comprehensive effect is best;
[0174] (3) The present invention can be seen from the comparison between Application Example 1 and Application Examples 21-25 that the amount of active metal atoms in the carrier and the active metal salt can improve the reaction conversion rate and the selectivity of geraniol within a certain range. When the amount of active metal atoms in the active metal salt ligand is less than 3.0% of the carrier mass, the catalyst activity is greatly reduced, resulting in a significant decrease in the reaction conversion rate and selectivity; when the amount of active metal atoms in the active metal salt ligand is higher than 7.0% of the carrier mass, the reaction selectivity and conversion rate are not significantly improved due to the limitation of the catalyst active site, but will lead to a waste of metal raw materials, which is not conducive to actual production. Therefore, considering the technical effect of the catalyst and the economic benefits in actual production, when the content of active metal atoms in the active metal salt is 3.0%-7.0% of the carrier mass, the production effect is best;
[0175] (4) By comparing Application Example 1 with Comparative Examples 1-4, it can be seen that the specific selection of the composition of the composite catalyst forms a specific system of active metal salt, carrier and ligand with a specific chiral cyclopentadiene skeleton. The specific system exerts a synergistic effect, so that the obtained composite catalyst has high catalytic activity and high selectivity in the reaction of selective catalytic hydrogenation of citral to prepare geraniol; when no ligand is added or the added ligand is not of the specific structure of the present invention, its conversion rate and selectivity are significantly reduced.
[0176] Gas chromatography analysis
[0177] The reaction solution of Example 26 was tested by gas chromatography, and the results were as follows: Figure 1 shown, and Figure 1 The corresponding specific data are shown in Table 3.
[0178] Table 3
[0179]
[0180] Combination Figure 1As shown in Table 3, there are no impurities in the corresponding reaction solution of the present invention, that is, the present invention can selectively catalytically hydrogenate citral into single high-purity geraniol by using a specific composite catalyst.
[0181] Catalyst application examples
[0182] The reaction liquid in Application Example 1 was filtered to recover Catalyst 1, and the recovered Catalyst 1 was further subjected to an application experiment. The reaction conditions and operation were the same as those in Application Example 1. The experimental results are shown in Table 4.
[0183] Table 4
[0184]
[0185] As can be seen from Table 4, after the specific composite catalyst provided by the present invention was used continuously for 10 times, its conversion rate only decreased by 0.15%, and its selectivity only decreased by 0.25%. Obviously, the specific composite catalyst has good stability and activity, good economic and practical value, and is suitable for large-scale industrial production.
[0186] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.
Claims
1. A composite catalyst, characterized in that: The composite catalyst comprises an active metal salt, a carrier and a ligand; the ligand has a chiral cyclopentadiene skeleton; The active metal salt includes any one of active metal nitrate, chloride, sulfate, acetate, acetylacetonate or hydrate thereof or a combination of at least two thereof; The active metal includes any one or a combination of at least two of Fe, Ni, Cu, Zn, Mn, Co, Bi, Pb or In; The carrier is a metal organic framework material; The ligand includes the compound shown in L1 and / or the compound shown in L2 below; 。 2. The composite catalyst according to claim 1, characterized in that The amount of active metal atoms in the active metal salt is 1.0%-10% of the mass of the carrier.
3. The composite catalyst according to claim 1, characterized in that The molar ratio of the ligand to the active metal atom in the active metal salt is (1-3):
1.
4. A method for preparing a composite catalyst as claimed in any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) dissolving an active metal salt in a solvent, adding a ligand, and mixing to obtain a metal complex solution; (2) Adding a carrier to the metal complex solution of step (1) for adsorption to obtain the composite catalyst.
5. The method for preparing the composite catalyst according to claim 4, characterized in that: The solvent in step (1) includes water; The mixing temperature in step (1) is 40-100°C; The mixing time in step (1) is 2-6 h; The adsorption temperature in step (2) is 30-60°C; The adsorption time in step (2) is 4-8 h.
6. A method for preparing geraniol by catalytic hydrogenation of citral, characterized in that: The method comprises: under the catalysis of the composite catalyst described in any one of claims 1 to 3, hydrogenating citral to obtain geraniol.
7. The method according to claim 6, characterized in that The amount of the composite catalyst is 1.0wt%-10.0wt% of the mass of citral; The raw material for the hydrogenation reaction also includes hydrogen.
8. The method according to claim 6, characterized in that The absolute pressure of the hydrogenation reaction is 1-6 MPa; The temperature of the hydrogenation reaction is 80-120°C; The hydrogenation reaction time is 1-4 h.