Surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatic hydrocarbon as well as preparation method and application of surface-coated Ru-based catalyst

Abstract

The invention discloses a surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatic hydrocarbon and a preparation method and application of the surface-coated Ru-based catalyst. The surface-coated Ru-based catalyst comprises a carrier; the active component is loaded on the carrier in a nanocluster form; and a coating; wherein the active component is Ru; and the coating is a hydrophobic material. The reaction substrate is cheap and easy to obtain; after the Ru / SiO2 catalyst is coated with hydrophobic silicon dioxide or C, the Ru / SiO2 catalyst has high catalytic activity and selectivity on a fluorinated aromatic hydrocarbon hydrogenation reaction, and the substrate applicability is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysis, and in particular relates to a surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics, and a preparation method and application thereof. Background Art

[0002] Fluorinated cycloalkanes are widely used in materials, agriculture and medicine, and are precursors of a variety of drugs, pesticides and liquid crystal materials. The strong dipole moment, high bond strength and relatively small space requirement of the CF bond can fine-tune the polarity, pKa value, conformation and metabolic stability of the compound, thereby improving the stability and lipophilicity of the compound. The synthesis of fluorinated alkanes is generally done by nucleophilic substitution, which requires toxic or difficult-to-handle reagents such as elemental fluorine, hydrogen fluoride and cesium fluoride sulfate, and usually has problems such as low selectivity and lengthy synthesis steps.

[0003] Fluorinated aromatics are a class of cheap and readily available compounds. If a suitable catalyst can be screened and fluorinated cycloalkanes can be synthesized by selective hydrogenation of aromatic rings, this method will be more efficient, safer and cleaner than synthesizing fluorinated cycloalkanes from alkanes by nucleophilic substitution. The main competing reaction for the hydrogenation of fluorinated aromatics to synthesize fluorinated cycloalkanes is the defluorination reaction, which is greatly affected by the solvent type. Polar solvents will greatly promote defluorination (Journal of Molecular Catalysis A, Chemical, 2004, 207, 59–68). In addition, the pH of the solution, the hydrogen pressure, the type of catalyst, etc. will affect the activity and selectivity of the reaction.

[0004] In 2017, F. Glorius et al. proposed the application of CAAC-coordinated Rh catalysts in the hydrogenation of fluorinated aromatics. The catalyst has high activity, fluorinated product selectivity and stereoselectivity in disubstituted or polysubstituted substrates (Science 2017, 357, 908–912). However, homogeneous catalysts are difficult to apply, the catalyst synthesis cost is high, and the catalytic reaction time is long. In 2020, W. Leitner et al. proposed to modify the surface of SiO2 carriers with long-chain alkanes such as n-decyltriethoxysilane, and the activity and selectivity of the Rh-loaded heterogeneous catalysts in fluorinated aromatic reactions were significantly improved (Catal. Sci. Technol., 2020, 10, 8120–8126). However, the preparation of catalyst carriers modified with key long-chain molecules is relatively complicated and costly. In addition, the active component in the catalysts used in the above two examples is metal Rh, which also leads to high catalyst costs.

[0005] In summary, there is currently no practical selective hydrogenation technology and catalytic system for fluorinated aromatics, and no relevant literature has been publicly reported. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] One of the objects of the present invention is to provide a surface-coated Ru-based catalyst for the selective hydrogenation of fluorinated aromatics, wherein the reaction substrate is cheap and readily available; after the Ru / SiO2 catalyst is coated with hydrophobic silica or C, it has high catalytic activity and selectivity for the hydrogenation reaction of fluorinated aromatics and has a wide range of substrate applicability.

[0009] In order to solve the above technical problems, the present invention provides the following technical solution: a surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics, comprising:

[0010] Carrier;

[0011] An active component loaded on a carrier in the form of nanoclusters; and

[0012] Coverings;

[0013] Wherein, the active component is Ru; and the coating is a hydrophobic material.

[0014] As a preferred embodiment of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics of the present invention, the carrier is one of silicon dioxide, magnesium oxide, aluminum oxide, hydroxyapatite and cerium oxide.

[0015] As a preferred embodiment of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics of the present invention, the loading amount of the active component is 0.4-1 wt%.

[0016] As a preferred embodiment of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics of the present invention, the coating is silicon dioxide, C, polyfurfuryl alcohol PFA, propyltriethoxysilane R3, octyltriethoxysilane R8, decyltriethoxysilane R 10 , Perfluorodecyltriethoxysilane R 10 One of F.

[0017] As a preferred embodiment of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics of the present invention, the mass ratio of the coating to the carrier is 0.1 to 2:1.

[0018] Another object of the present invention is to provide a method for preparing the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics as described above, comprising:

[0019] Provide a carrier;

[0020] The active components are loaded on the carrier in the form of nanoclusters;

[0021] The coating is surface coated.

[0022] Another object of the present invention is to provide the use of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics as described above in the selective hydrogenation of fluorinated aromatics to fluorinated cycloalkanes.

[0023] As a preferred embodiment of the present invention, the catalyst, solvent, fluorinated aromatic hydrocarbon and additive are mixed and the reaction time is 1 to 3 hours.

[0024] As a preferred embodiment of the present invention, the solvent is one of n-hexane, toluene, dichloromethane, ethanol, and a mixture of n-hexane and water, and the concentration of the fluorinated aromatic hydrocarbon substrate in the solvent is 0.1 to 1.0 mol / L;

[0025] The additive is calcium oxide, and the amount added is 0.2 to 1.0 molar equivalent of the fluorinated aromatic hydrocarbon;

[0026] The reaction temperature is 30-80° C., and the reaction pressure is 0.5-2.0 MPa.

[0027] As a preferred embodiment of the present invention, the fluorinated aromatic hydrocarbon is selected from one of fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 4-methylfluorobenzene, 4-ethylfluorobenzene, 2-methylfluorobenzene, 3-methylfluorobenzene, trifluoromethylbenzene and difluoromethylbenzene.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The reaction substrates of the present invention are cheap and easily available; after the Ru / SiO2 catalyst is coated with hydrophobic silicon dioxide or carbon, the catalytic activity and selectivity of the catalyst for the hydrogenation reaction of fluorinated aromatic hydrocarbons are high, and the substrate applicability is wide; the preparation method of the catalyst of the present invention is simple and easy, and can be synthesized using a relatively cheap Ru precursor, a commercial carrier and a coating, and can be recycled; the reaction system is clean, safe, and highly operable, and has important economic and practical value for the efficient preparation of fluorinated cycloalkanes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0031] Figure 1 This is a transmission electron microscope image of the Ru@SiO2 / SiO2 (R=0.3) catalyst of the present invention;

[0032] Figure 2 The particle size statistics of Ru nanoparticles of the Ru@SiO2 / SiO2 (R=0.3) catalyst of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0036] Unless otherwise specified, the raw materials used in the examples were purchased commercially.

[0037] Example 1

[0038] (1) Taking 1.0wt% Ru / SiO2 as an example: add the pre-prepared Ru (4.87mg / mL, 2.05mL) ethanol standard solution into 10mL of anhydrous ethanol, stir for 10min, then add 1.0g SiO2 carrier, stir dry in an 80℃ water bath, and then dry in an 80℃ oven;

[0039] (2) The powder was then heated from room temperature to 300°C at a heating rate of 5°C / min in a vertical tube furnace under a 10 vol% H2 / Ar atmosphere, and reduced for 2 h to obtain 1.0 wt% Ru / SiO2.

[0040] The noble metal precursor solution was changed, and 1.0wt% Rh / SiO2, 1.0wt% Pt / SiO2, and 5.0wt% Ni / SiO2 were obtained in the same way. A series of noble metal catalysts prepared in Example 1 were used in the catalytic reaction of fluorobenzene hydrogenation to fluorocyclohexane, and 0.5mol% (based on noble metal) of the above catalyst, 5.0mL n-hexane, 0.5mmol fluorobenzene and 28mg calcium oxide were added to a high-pressure reactor. The reaction was carried out under 1.0MPa H2 atmosphere at 80°C for 1.0h, and the products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 1.

[0041] Table 1

[0042]

[0043]

[0044] As can be seen from Table 1, when Ru, Rh, and Pt are used as active metals, the catalysts with SiO2 as the carrier have a high conversion rate (>90%), among which 1.0wt% Ru / SiO2 and 1.0wt% Rh / SiO2 both have a fluorocyclohexane hydrogenation selectivity higher than 80%. The Pt-based catalyst has a very low hydrogenation selectivity for fluorocyclohexane, while the Ni-based catalyst has an extremely low hydrogenation activity. Since the Ru-based catalyst also has high activity and fluorocyclohexane hydrogenation selectivity, and considering the extremely expensive price of the Rh precursor in the market, the relatively cheap Ru metal was selected for subsequent exploration and screening.

[0045] Example 2

[0046] The catalyst preparation of this Example 2 is consistent with steps (1) and (2) in Example 1. In addition to silicon dioxide, catalysts with magnesium oxide, aluminum oxide, hydroxyapatite, and cerium oxide as carriers are also prepared, and are named 1.0wt% Ru / MgO, 1.0wt% Ru / Al2O3, 1.0wt% Ru / HAP, and 1.0wt% Ru / CeO2, respectively.

[0047] The Ru catalysts supported on different carriers prepared in Example 2 were used for the catalytic reaction of hydrogenation of fluorobenzene. 25.3 mg (0.25 mol%, based on the amount of fluorobenzene) of any catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were placed in a high pressure reactor and reacted at 1.0 MPa H2 and 50°C for 3 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS), and the results are shown in Table 2.

[0048] Table 2

[0049]

[0050] As can be seen from Table 2, the hydrogenation activity and selectivity of the catalyst supported by silica carrier are higher than those of the catalyst supported by other carriers. Under the conditions of this example, the reaction conversion rate is 76% and the selectivity of fluorocyclohexane is 84%. When MgO, Al2O3, HAP and CeO2 are used as carriers, the activity and selectivity are poor. Therefore, in subsequent experiments, the Ru catalyst supported by silica carrier is selected for further practical exploration.

[0051] Example 3

[0052] The preparation of the 1.0wt% Ru / SiO2 catalyst in Example 3 is consistent with steps (1) and (2) in Example 1. SiO2 is coated on the catalyst surface in a specific manner to prepare Ru@SiO2 / SiO2. The specific implementation methods are as follows.

[0053] Take 0.5g hexadecyltrimethylammonium bromide (CTAB) and dissolve it in 100mL ethanol, then add about 5.0mL ammonia water (25% to 28% wt%), add 0.4g of 1.0wt% Ru / SiO2 catalyst after reduction treatment, and stir for 30 minutes in a sealed container. After stirring, add a certain amount of TEOS to start coating the catalyst surface. The ratio of the surface SiO2 coating amount to the amount of SiO2 on the catalyst carrier itself is recorded as R. Taking R=0.3 as an example, the amount of TEOS added is 0.416g (if R is not indicated, the R value of Ru@SiO2 / SiO2 is assumed to be 0.3). After stirring for 12 hours, stir the suspension in an 80℃ water bath, dry it in a 100℃ oven, and roast it in air at 550℃ for 4 hours. Grind it after roasting.

[0054] Subsequently, the powder was heated from room temperature to 300°C at a heating rate of 5°C / min in a vertical tube furnace under a 10 vol% H2 / Ar atmosphere, and reduced for 2 h to obtain Ru@SiO2 / SiO2.

[0055] The transmission electron microscopy image of the Ru@SiO2 / SiO2 (R=0.3) catalyst prepared in this example is as follows Figure 1 As shown; the Ru nanoparticle size statistics of the Ru@SiO2 / SiO2 (R=0.3) catalyst prepared in this example are as follows Figure 2 shown.

[0056] By changing the amount of TEOS added, Ru@SiO2 / SiO2 with different coating amounts was obtained in the same method, and R was 0.1, 0.2, 0.3, 0.6, and 1.0 respectively. A series of Ru@SiO2 / SiO2 catalysts with different coating amounts prepared in Example 3 were used in the catalytic reaction of fluorobenzene hydrogenation, and 0.125 mol% Ru of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high-pressure reactor, respectively, and the reaction was carried out at 1.0 MPa H2 and 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 3.

[0057] Table 3

[0058]

[0059]

[0060] As can be seen from Table 3, after coating with SiO2, the selectivity of Ru@SiO2 / SiO2 catalyzing fluorobenzene hydrogenation is significantly improved, and with the increase of the coating amount, it first increases and then decreases, but when R=0.1, 0.2, the activity of the catalytic reaction is basically not improved. Among them, when R=0.3, the activity and selectivity of the catalyst catalytic reaction are significantly improved compared with the uncoated case, and the reaction conversion rate reaches 47% under the conditions of this embodiment, and the selectivity for fluorocyclohexane is as high as 93%.

[0061] Example 4

[0062] The preparation of the 1.0 wt% Ru / SiO2 catalyst in Example 4 is consistent with steps (1) and (2) in Example 1. Ru@C / SiO2 is prepared by coating C on the catalyst surface in a specific manner. The specific implementation methods are as follows.

[0063] Take 0.5g of the reduced 1.0wt% Ru / SiO2 catalyst and dissolve it in 100mL tris buffer. Ultrasonicate for 30min, place the solution in a 40℃ water bath, and drop dopamine solution (dissolved in 2.5mL water). The ratio of the amount of SiO2 in the catalyst carrier to the amount of dopamine added is R. C , with R C =5 as an example, the amount of dopamine added is 0.1 g. The above solution is then stirred continuously for 24 h. The resulting suspension is centrifuged, washed twice with deionized water, once with ethanol, and dried overnight at 60 °C. The powder is calcined at 750 °C in a N2 flow at a heating rate of 5 °C / min for 2 h.

[0064] Subsequently, the powder was heated from room temperature to 300°C at a heating rate of 5°C / min in a vertical tube furnace under a 10 vol% H2 / Ar atmosphere, and reduced for 2 h to obtain Ru@C / SiO2.

[0065] By changing the amount of dopamine added, different coating amounts of Ru@C / SiO2 were obtained by the same method. C The Ru@C / SiO2 catalysts with different coating amounts prepared in Example 3 were used in the catalytic reaction of fluorobenzene hydrogenation. 0.125 mol% Ru of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high-pressure reactor, and the reaction was carried out at 1.0 MPaH2 and 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 4.

[0066] Table 4

[0067]

[0068]

[0069] It can be seen from Table 4 that after coating with SiO2, the selectivity of Ru@C / SiO2 catalyzed fluorobenzene hydrogenation was significantly improved, but the activity of the catalytic reaction was not significantly improved. C =5.0, the activity and selectivity of the catalytic reaction of the catalyst are significantly improved compared with the uncoated case, the reaction conversion rate reaches 18% under the conditions of this embodiment, and the selectivity for fluorocyclohexane is as high as 94%.

[0070] Example 5

[0071] The catalyst preparation of this Example 5 is consistent with steps (1) and (2) in Example 1. The ruthenium loading amount is changed to prepare Ru / SiO2 catalysts with loading amounts of 0.1wt%, 0.4wt%, 1wt%, and 5wt%, respectively. Then, Ru@SiO2 / SiO2 catalysts with R=0.3 are prepared according to the method in Example 3, and are recorded as 0.1wt% Ru@SiO2 / SiO2, 0.4wt% Ru@SiO2 / SiO2, 1wt% Ru@SiO2 / SiO2, and 5wt% Ru@SiO2 / SiO2, respectively.

[0072] A series of catalysts with different ruthenium loadings prepared in Example 5 were used in the catalytic reaction of fluorobenzene hydrogenation. 0.125 mol% Ru of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high-pressure reactor, and the reaction was carried out at 1.0 MPa H2 and 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 5. 5

[0074]

[0075] As can be seen from Table 5, as the Ru loading increases from 0.1wt% to 1.0wt%, the activity and selectivity of fluorobenzene increase accordingly; and when the loading further increases to 5wt%, the conversion rate of fluorobenzene decreases significantly, from 60% to 22%.

[0076] Example 6

[0077] The 1.0wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 was used in the catalytic reaction of fluorobenzene hydrogenation at different temperatures. 0.125mol% (based on the amount of fluorobenzene substance) of the above catalyst, 5.0mL of n-hexane, 1.0mmol of fluorobenzene and 56mg of calcium oxide were added into a high-pressure reactor, and the reaction was carried out under 1.0MPa H2 at 30°C, 50°C and 80°C for 1.0h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 6.

[0078] Table 6

[0079]

[0080] It can be seen from Table 6 that the reaction temperature has a great influence on the conversion rate of the reaction, which increases with increasing temperature. When the temperature reaches 80°C, the fluorobenzene conversion rate is close to 100%, while the temperature has little effect on the selectivity of the reaction.

[0081] Example 7

[0082] The 1.0 wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 was used in the catalytic reaction of fluorobenzene hydrogenation under different hydrogen pressures. 0.125 mol% (based on the amount of fluorobenzene substance) of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added into a high-pressure reactor, and the reaction was carried out at 50°C for 1.0 h under 0.5 MPa H2, 1.0 MPa H2 and 2.0 MPa H2, respectively. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 7.

[0083] Table 7

[0084]

[0085]

[0086] It can be seen from Table 7 that when the hydrogen pressure increases, the conversion rate of the reaction increases significantly, while the selectivity of the fluorocyclohexane product does not change significantly.

[0087] Example 8

[0088] Different amounts of the 1.0 wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 were used in the catalytic reaction of fluorobenzene hydrogenation. 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high-pressure reactor, and 0.125 mol% (based on the amount of fluorobenzene), 0.25 mol% and 0.5 mol% of the above catalyst were added. The reaction was carried out at 1.0 MPa H2 at 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 8.

[0089] Table 8

[0090]

[0091] It can be seen from Table 8 that when the amount of catalyst increases, the conversion rate of the reaction increases significantly, while the selectivity of fluorocyclohexane does not change substantially.

[0092] Example 9

[0093] The 1.0wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 was used in the catalytic reaction of fluorobenzene hydrogenation under different conditions of calcium oxide addition. 0.125mol% (based on the amount of fluorobenzene substance) of the above catalyst, 5.0mL n-hexane, 1.0mmol fluorobenzene, and 0, 11.2mg, 28mg, 56mg, and 112mg calcium oxide (0-2.0 substrate molar equivalent) were added to a high-pressure reactor, and the reaction was carried out at 1.0MPa H2 and 50°C for 1.0h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 9.

[0094] Table 9

[0095]

[0096]

[0097] As can be seen from Table 9, when the amount of CaO added is 0 or 0.2 substrate molar equivalents, the conversion rate and fluorocyclohexane selectivity of the reaction are low, and the conversion rate is only 8.0% when no CaO is added. When the amount of calcium oxide added is 0.5 to 2.0 substrate molar equivalents, there is no obvious difference in the reaction results, the reaction conversion rate is about 50% and the selectivity is above 92%. Therefore, this reaction system needs to add 0.5 substrate molar equivalents or more of calcium oxide.

[0098] Example 10

[0099] The 1.0wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 was used in the catalytic reaction of fluorobenzene hydrogenation under different solvent conditions. 0.125mol% (based on the amount of fluorobenzene substance) of the above catalyst, 5.0mL solvent, 1.0mmol fluorobenzene and 56mg calcium oxide were added to a high-pressure reactor. The solvents were n-hexane, toluene, dichloromethane, ethanol, and a mixed solvent of n-hexane / water (containing 2.0mL water). The reaction was carried out at 1.0MPa H2 and 50°C for 1.0h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 10.

[0100] Table 10

[0101]

[0102] It can be seen from Table 10 that with the gradual increase of the polarity of the solvent, the selectivity of the fluorocyclohexane product basically shows a gradually decreasing trend, while the conversion rate of the reaction system in n-hexane and toluene is higher. In summary, n-hexane is the best solvent to obtain the product fluorocyclohexane.

[0103] Embodiment 11

[0104] The 1.0 wt% Ru@SiO2 / SiO2 catalyst prepared in Example 3 was applied to the catalytic hydrogenation reaction of different fluorinated aromatic substrates. 0.125 mol% (based on the amount of fluorobenzene) of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorinated aromatic substrate and 56 mg of calcium oxide were added to a high-pressure reactor and reacted for 3 hours. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 11.

[0105] Table 11

[0106]

[0107]

[0108] It can be seen from Table 11 that the 1.0wt% Ru@SiO2 / SiO2 catalyst exhibits good reactivity and selectivity for fluorinated products in the hydrogenation reaction of fluorinated aromatic compounds containing different functional groups. Therefore, the 1.0wt% Ru@SiO2 / SiO2 catalyst has good substrate universality.

[0109] Example 12

[0110] The preparation of the 1.0wt% Ru / SiO2 catalyst in this Example 12 is consistent with steps (1) and (2) in Example 1. PFA is coated on the catalyst surface in a specific manner to prepare Ru@PFA / SiO2. The specific implementation methods are as follows.

[0111] Add 80mL of deionized water and 2.0g of PVP to a flask. Stir the mixture at 600rpm until the PVP is completely dissolved, then add 1.0g of FA to the flask. The sample is reacted at 1000rpm in a 120℃ sand bath for 18h. After the reaction is completed, the mixture is cooled, centrifuged and the brown precipitate is washed. Add 6.0ml of ethanol to the precipitate and ultrasonicate for 30min. Mix 1.0g of 1.0wt% Ru / SiO2 catalyst with the above PFA mixture, and record the ratio of the surface PFA coating amount to the amount of SiO2 on the catalyst carrier itself as R P , with R P = 1.0, the amount of PFA added is 1.0 g, that is, 6.0 mL of the mixed solution of PFA and ethanol is added (if R is not indicated P , R of Ru@PFA / SiO2 P The value defaults to 1.0). Fire at 520°C for one hour.

[0112] Subsequently, the powder was heated from room temperature to 300°C at a heating rate of 5°C / min in a vertical tube furnace under a 10 vol% H2 / Ar atmosphere, and reduced for 2 h to obtain Ru@PFA / SiO2.

[0113] By changing the amount of PFA added, different coating amounts of Ru@PFA / SiO2 were obtained by the same method. P A series of Ru@PFA / SiO2 catalysts with different coating amounts prepared in this example were used in the catalytic reaction of fluorobenzene hydrogenation. 0.125 mol% Ru of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high-pressure reactor, and the reaction was carried out at 1.0 MPa H2 and 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 12.

[0114] Table 12

[0115]

[0116] It can be seen from Table 12 that after coating with PFA, the selectivity and activity of Ru@PFA / SiO2 in catalytic hydrogenation of fluorobenzene are significantly lower than those of the catalyst coated with SiO2, and the activity and selectivity are lower with the increase of the coating amount, which indicates that the catalytic performance of Ru@SiO2 / SiO2 is better.

[0117] Embodiment 13

[0118] The preparation of the 1.0 wt% Ru / SiO2 catalyst in Example 13 is consistent with steps (1) and (2) in Example 1. The Ru@R X / SiO2, the specific implementation methods are as follows.

[0119] Taking propyltriethoxysilane (denoted as R3) as an example, propyltriethoxysilane (4.0 mmol) was added to a suspension containing 1.0 g of 1.0 wt% Ru / SiO2 and 30 mL of toluene under a nitrogen atmosphere. The resulting mixture was refluxed at 130°C under Ar for 18 hours. After 18 hours, the toluene was removed by rotary evaporation, and the resulting catalyst was washed with dichloromethane and dried overnight at 60°C in vacuum.

[0120] Subsequently, the powder was heated from room temperature to 300°C at a heating rate of 5°C / min in a vertical tube furnace under a 10 vol% H2 / Ar atmosphere, and reduced for 2 h to obtain Ru@R3 / SiO2.

[0121] In addition to Ru@R3 / SiO2, catalysts coated with octyltriethoxysilane, decyltriethoxysilane, and perfluorodecyltriethoxysilane were prepared by the same method and were denoted as Ru@R8 / SiO2, Ru@R 10 / SiO2、Ru@R 10 F / SiO2. A series of Ru@R X / SiO2 catalyst was used in the catalytic reaction of fluorobenzene hydrogenation. 0.125 mol%Ru of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added into a high-pressure reactor respectively. The reaction was carried out at 1.0 MPa H2 and 50°C for 1.0 h. The products and yields were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). The results are shown in Table 13.

[0122] Table 13

[0123]

[0124] It can be seen from Table 13 that Ru@R x / SiO2 is generally lower in selectivity and activity for fluorobenzene hydrogenation than that of the catalyst coated with SiO2, which indicates that Ru@SiO2 / SiO2 has better catalytic performance.

[0125] Embodiment 14

[0126] The preparation of the coated catalyst in this Example 14 is consistent with the steps in Example 3. In addition to 1.0wt% Ru@SiO2 / SiO2, catalysts with rhodium, platinum and nickel as active substances are also prepared, named 1.0wt% Rh@SiO2 / SiO2, 1.0wt% Pt@SiO2 / SiO2, and 1.0wt% Ni@SiO2 / SiO2, respectively.

[0127] The catalyst prepared in Example 14 was used for the catalytic reaction of fluorobenzene hydrogenation. 0.125 mol% (based on precious metal) of the above catalyst, 5.0 mL of n-hexane, 1.0 mmol of fluorobenzene and 56 mg of calcium oxide were added to a high pressure reactor, and the reaction was carried out at 1.0 MPaH2 and 50°C for 1.0 h. The product and yield were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS), and the results are shown in Table 14.

[0128] Table 14

[0129]

[0130]

[0131] As can be seen from Table 14, Rh@SiO2 / SiO2 and Pt@SiO2 / SiO2 catalysts have higher reaction activity than Ru@SiO2 / SiO2 catalyst, but the reaction selectivity of Rh@SiO2 / SiO2 catalyst is slightly lower than that of Ru@SiO2 / SiO2, and the catalytic selectivity of Pt@SiO2 / SiO2 catalyst for fluorocyclohexane is lower. The catalytic activity of Ni@SiO2 / SiO2 catalyst is relatively low, and there is no catalytic selectivity for fluorocyclohexane. In summary, it can be shown that Ru@SiO2 / SiO2 has the best catalytic performance.

[0132] The present invention uses fluorinated aromatic hydrocarbons as substrates for one-step hydrogenation to prepare fluorinated cycloalkanes. The substrates are cheap and readily available. Under mild conditions, a high conversion rate of fluorinated aromatic hydrocarbons and selectivity for fluorinated cycloalkanes can be achieved. The reaction process is clean, safe, and energy-efficient. The active metal precursors, carriers, and coatings used in the preparation of the catalysts of the present invention are all cheap and readily available, and the preparation method is simple and rapid. The substrates have wide applicability. In view of the above advantages, the present invention has good economic value and industrial application prospects in the efficient preparation of fluorinated cycloalkanes.

[0133] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics, characterized in that: include, Carrier; The active components are loaded on the carrier in the form of nanoclusters; as well as, Coverings; Wherein, the active component is Ru; and the coating is a hydrophobic material.

2. The surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to claim 1, characterized in that: The carrier is one of silicon dioxide, magnesium oxide, aluminum oxide, hydroxyapatite and cerium oxide.

3. The surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to claim 1 or 2, characterized in that: The loading amount of the active component is 0.4-1 wt%.

4. The surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to claim 3, characterized in that: The coating material is silicon dioxide, C, polyfurfuryl alcohol PFA, propyl triethoxysilane R3, octyl triethoxysilane R8, decyl triethoxysilane R 10 , Perfluorodecyltriethoxysilane R 10 One of F.

5. The surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to claim 4, characterized in that: The mass ratio of the coating to the carrier is 0.1 to 2:

1.

6. The method for preparing a surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to any one of claims 1 to 5, characterized in that: include, Provide a carrier; The active components are loaded on the carrier in the form of nanoclusters; The coating is surface coated.

7. Use of the surface-coated Ru-based catalyst for selective hydrogenation of fluorinated aromatics according to any one of claims 1 to 5 in the selective hydrogenation of fluorinated aromatics to fluorinated cycloalkanes.

8. The use according to claim 7, characterized in that: The catalyst, solvent, fluorinated aromatic hydrocarbon and additive are mixed and the reaction time is 1 to 3 hours.

9. The use according to claim 8, characterized in that: The solvent is one of n-hexane, toluene, dichloromethane, ethanol, and a mixture of n-hexane and water, and the concentration of the fluorinated aromatic hydrocarbon substrate in the solvent is 0.1 to 1.0 mol / L; The additive is calcium oxide, and the amount added is 0.2 to 1.0 molar equivalent of the fluorinated aromatic hydrocarbon; The reaction temperature is 30-80° C., and the reaction pressure is 0.5-2.0 MPa.

10. The use according to any one of claims 7 to 9, characterized in that: The fluorinated aromatic hydrocarbon is selected from one of fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 4-methylfluorobenzene, 4-ethylfluorobenzene, 2-methylfluorobenzene, 3-methylfluorobenzene, trifluoromethylbenzene and difluoromethylbenzene.

Images