Highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether and preparation method thereof

Abstract

The invention discloses a high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether and a preparation method thereof, specifically a high-activity single-atom Ru1 / CeO2-X catalyst for synthesizing bio-based cyclohexanediol monomethyl ether and a preparation method thereof, which not only solves the problem of uneven dispersion of conventional single-atom Ru in the catalyst, but also can achieve complete hydrogenation of lignin-derived phenol in a short time, low pressure and low temperature during the synthesis of bio-based cyclohexanediol monomethyl ether while inhibiting the breakage of ether bonds, thereby improving the selectivity of bio-based cyclohexanediol monomethyl ether (>95%).

Description

[Technical field]

[0001] The present invention belongs to the technical field of catalysts, and relates to a high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether and a preparation method thereof, and particularly relates to a high-activity single-atom Ru catalyst for synthesizing bio-based cyclohexanediol monomethyl ether. 1 / CeO 2 -X catalyst and its preparation method. [Background technology]

[0002] Alcohol ethers have excellent surface activity and are widely used, so their consumption increases year by year. In addition to being used to prepare civilian detergents, alcohol ethers are also widely used in industries such as textiles, printing and dyeing, coatings, metal processing, mining and cosmetics. Among them, cyclohexanediol monomethyl ether, as a cyclic glycol monoether, has a wide range of uses in the synthesis of antibacterial drugs, bioactive molecules and chiral additives.

[0003] The industrial method for synthesizing cyclohexanediol monomethyl ether is mainly to use cyclohexene oxide and methanol to react with nucleophilic reaction in the presence of an acidic catalyst. However, the cyclohexene oxide or cyclohexene used in the synthesis has high production cost, is highly flammable, has poor stability, is difficult to store, and is mostly carried out under homogeneous acidic catalyst conditions. Such catalysts are difficult to recover and are prone to corroding equipment.

[0004] The synthesis of bio-based cyclohexanediol monomethyl ether can be obtained by using lignin-derived phenol as raw material to completely hydrogenate the benzene ring. However, the synthesis of bio-based cyclohexanediol monomethyl ether requires finding a suitable catalytic system to completely hydrogenate the benzene ring and inhibit the cleavage of the CO bond. On the one hand, the intramolecular hydrogen bond formed by lignin-derived phenol reduces the Csp 2 -OCH 3 The bond energy of the bond will promote Csp 2 -OCH 3 bond cleavage; on the other hand, the ether bond of cyclohexanediol monomethyl ether is lower than Csp 2 -OCH 3 bond, which makes it easy for lignin-derived phenol to hydrogenate to form cyclohexanediol monomethyl ether, which then further reacts to form cyclohexanol.

[0005] Therefore, in order to improve the selectivity of bio-based cyclohexanediol monomethyl ether, it is usually necessary to lower the reaction temperature, increase the reaction time and reaction pressure, which will greatly increase the production cost. [Summary of the invention]

[0006] In view of the problem that in the current process of synthesizing bio-based cyclohexanediol monomethyl ether, in order to improve the selectivity of bio-based cyclohexanediol monomethyl ether, it is necessary to reduce the reaction temperature, increase the reaction time and reaction pressure, but this will greatly increase the production cost, the present invention provides a high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether and a preparation method thereof, specifically a high-activity single-atom Ru for synthesizing bio-based cyclohexanediol monomethyl ether 1 / CeO 2 -X catalyst and its preparation method not only solve the problem of uneven dispersion of conventional single-atom Ru in catalysts, but also can achieve complete hydrogenation of lignin-derived phenol in a short time, low pressure and low temperature during the synthesis of bio-based cyclohexanediol monomethyl ether while inhibiting the breakage of ether bonds, thereby improving the selectivity of bio-based cyclohexanediol monomethyl ether (>95%).

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0008] The method for preparing a highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether comprises the following steps:

[0009] 1) Prepare the raw materials according to the following ratio to prepare the carrier CeO 2 -X: 1.737 g cerium nitrate hexahydrate, 1-20 g sodium hydroxide, 0.01-1 g trisodium phosphate, 5-50 ml deionized water;

[0010] 1.737 g of cerous nitrate hexahydrate is added to deionized water and fully dissolved at a speed of 600 rpm to obtain a solution, and 1-20 g of sodium hydroxide or 0.01-1 g of trisodium phosphate or a mixture of the two is added to the solution, and the mixture is mixed in any proportion; after stirring at room temperature for 30 minutes, the solution is transferred to an autoclave equipped with a polytetrafluoroethylene liner and placed in a constant temperature drying oven, and heated at a constant temperature of 150-250° C. for 5-30 hours. After cooling to room temperature, the solid-liquid mixture is centrifuged to take out the solid, and the remaining solid is fully washed with deionized water for 3-8 times, and then vacuum dried at 60° C. and calcined in air at 500° C. for 3 hours to obtain CeO 2 -X (where X is O, S, or R, representing octahedron, cube, or rod, respectively);

[0011] 2) Take 50 mg CeO 2 Disperse in 20 ml of deionized water, then take 1-10 mg of hydrated ruthenium chloride and dissolve it in 10 ml of deionized water. Add the ruthenium chloride aqueous solution dropwise to the CeO 2 The dispersion was stirred vigorously for 6 h at a speed of 300-800 rpm, centrifuged, washed with deionized water 3-8 times, dried in a vacuum at 60 °C, and then heated in a tube furnace for 1 0.5 h. 2The highly active single-atom catalyst (Ru 1 / CeO 2 -X catalyst), which improves the selectivity of bio-based cyclohexanediol monomethyl ether by more than 95% during the synthesis of bio-based cyclohexanediol monomethyl ether.

[0012] The present invention also relates to a highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether, which is obtained by using the above-mentioned preparation method of the highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether. 1 / CeO 2 -X catalyst mainly exposed CeO 2 (111) crystal plane; Ru 1 / CeO 2 -X catalyst single grain size is 50-200nm; Ru 1 / CeO 2 The mass loading of Ru in the -X catalyst is 0.3-0.8%, Ru 1 / CeO 2 No Ru nanoparticles were present in the -X catalyst.

[0013] The present invention also relates to the use of the above-mentioned high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether, comprising the following steps:

[0014] 1) Prepare the raw materials according to the following ratio: 100-500 mg of lignin-derived phenol, Ru 1 / CeO 2 -X catalyst 5-20mg, n-octane 3ml;

[0015] 2) Saturation reaction of lignin-derived phenol: lignin-derived phenol and Ru 1 / CeO 2 -X catalyst is added into a high-pressure reactor, and solvent n-octane is added, and hydrogen is charged. The reaction conditions are: room temperature to 120°C, reaction time 1-4h, reaction pressure 0.5-4.0MPa, to complete the catalytic reaction.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The method for preparing a highly active single-atom catalyst according to the present invention utilizes freely moving Ru cations and CeO 2 The negatively charged oxygen atoms in the CeO2 matrix can form a strong adsorption effect, making the single-atom Ru uniformly dispersed in the carrier CeO2. 2 The surface solves the problem of uneven dispersion of single-atom Ru.

[0018] 2. A highly active single-atom catalyst according to the present invention, which has more (111) crystal faces of CeO exposed. 2 The larger the crystal size, the easier it is for lignin-derived phenol to react with CeO on the (111) surface. 2 Planar adsorption is formed to quickly complete the hydrogenation reaction, and the Ru-O-Ce active site is difficult to activate the CO bond of the substrate at a lower temperature, thereby achieving the purpose of highly selectively generating bio-based cyclohexanediol monomethyl ether, successfully solving the problem of low selectivity of bio-based cyclohexanediol monomethyl ether.

Brief Description of the Drawings

[0019] Figure 1 The Ru exposed (111) crystal surface of the highly active single atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 of the present invention 1 / CeO 2 -X spherical aberration electron microscope image (illustration is Figure 1 Fast Fourier transform of

[0020] Figure 2 The highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 of the present invention has a single Ru atom with a size of 150-200 nm. 1 / CeO 2 -X transmission electron microscope image;

[0021] Figure 3 2D HSQC NMR comparison spectra of the highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 of the present invention before and after the reaction in real lignin oil;

[0022] Figure 4 This is a graph showing the data obtained from the reaction of real lignin oil using the highly active single atom catalyst prepared in Example 4 of the present invention for synthesizing bio-based cyclohexanediol monomethyl ether. [Specific implementation method]

[0023] The present invention is further described in detail below in conjunction with specific examples, but the examples do not limit the present invention in any form. In addition, after reading the content of the present invention, those skilled in the art can make various forms of changes or modifications to the present invention, and these equivalent forms also belong to the scope limited by the claims attached to this application.

[0024] The method for preparing a high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether comprises the following steps:

[0025] Raw materials: 1.737 g cerium nitrate hexahydrate, 0.0152 g trisodium phosphate, 15 g sodium hydroxide, 150 ml deionized water, 1 mg hydrated ruthenium trichloride;

[0026] Embodiment 1:

[0027] CeO 2 -O preparation method: the raw materials include 1.737g of cerous nitrate hexahydrate, 0.0152g of trisodium phosphate, and 120ml of deionized water;

[0028] 1.737 g of cerous nitrate hexahydrate was added to deionized water and fully dissolved at 600 rpm. 0.0152 g of trisodium phosphate was added to the solution and stirred at room temperature for 30 minutes. The solution was transferred to an autoclave lined with polytetrafluoroethylene and placed in a constant temperature drying oven. It was heated at 170 ° C for 12 hours. After cooling to , the solid-liquid mixture was centrifuged to remove the solid, and the remaining solid was fully washed 5 times with deionized water. After vacuum drying at 60 ° C, it was calcined at 500 ° C in air for 3 hours to obtain a series of CeO 2 -O.

[0029] Embodiment 2:

[0030] CeO 2 -S preparation method: the raw materials include 1.737g cerium nitrate hexahydrate, 15g sodium hydroxide, and 120ml deionized water;

[0031] 1.737 g of cerous nitrate hexahydrate was added to deionized water and fully dissolved at 600 rpm. 15 g of sodium hydroxide was added to the solution and stirred at room temperature for 30 minutes. The solution was transferred to an autoclave lined with polytetrafluoroethylene and placed in a constant temperature drying oven. It was heated at 180 ° C for 24 hours. After cooling to , the solid-liquid mixture was centrifuged to remove the solid, and the remaining solid was fully washed 5 times with deionized water. After vacuum drying at 60 ° C, it was calcined at 500 ° C in air for 3 hours to obtain a series of CeO 2 -S.

[0032] Embodiment 3:

[0033] CeO 2 -R preparation method: the raw materials include 1.737g cerium nitrate hexahydrate, 15g sodium hydroxide, and 120ml deionized water;

[0034] 1.737 g of cerous nitrate hexahydrate was added to deionized water and fully dissolved at 600 rpm. 15 g of sodium hydroxide was added to the solution and stirred at room temperature for 30 minutes. The solution was transferred to an autoclave lined with polytetrafluoroethylene and placed in a constant temperature drying oven. It was heated at 100 °C for 24 hours. After cooling to , the solid-liquid mixture was centrifuged to remove the solid, and the remaining solid was fully washed 5 times with deionized water. After vacuum drying at 60 °C, it was calcined at 500 °C in air for 3 hours to obtain a series of CeO 2 -R.

[0035] Embodiment 4:

[0036] Preparation method of highly active single-atom catalyst: raw materials include CeO 2 -X 50mg, hydrated ruthenium trichloride 1mg, deionized water 30ml;

[0037] Take 50 mg CeO 2 -X was dispersed in 20 ml of deionized water, and 1 mg of hydrated ruthenium chloride was dissolved in 10 ml of deionized water. The ruthenium chloride aqueous solution was added dropwise to CeO 2 -X dispersion, stirred vigorously at 600 rpm for 6 h, centrifuged, washed 5 times with deionized water, dried under vacuum at 60 °C, and then heated in a tube furnace for 1 0.5 h. 2 Ru was obtained by reduction at 600℃ for 3h under atmosphere. 1 / CeO 2 -X (which includes Ru 1 / CeO 2 -R, Ru 1 / CeO 2 -S, Ru 1 / CeO 2 -O).

[0038] Figure 1 The Ru exposed (111) crystal surface of the highly active single atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 1 / CeO 2 -X spherical aberration electron microscope image (illustration is Figure 1 Fast Fourier transform of

[0039] Figure 2 The highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 has a single Ru atom with a size of 150-200 nm. 1 / CeO 2 -X transmission electron microscope image;

[0040] Figure 3 2D HSQC NMR comparison spectra of the highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether prepared in Example 4 before and after the reaction in real lignin oil.

[0041] Embodiment 5:

[0042] An application of a high-activity single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether comprises the following steps:

[0043] 1) Prepare the raw materials according to the following ratio: 166 mg of lignin-derived phenol, 30 mg of highly active single-atom catalyst, and 3 ml of solvent n-octane;

[0044] 2) Carry out saturation reaction of lignin-derived phenol: add lignin-derived phenol and high-activity single-atom catalyst into a high-pressure reactor, add solvent, and fill with hydrogen. The reaction conditions are: 120° C., reaction time 4 h, reaction pressure 3 MPa, and complete the catalytic reaction.

[0045] Figure 4 This is a graph showing the data obtained from the reaction of real lignin oil using the highly active single atom catalyst prepared in Example 4 for the synthesis of bio-based cyclohexanediol monomethyl ether.

[0046] result:

[0047] (1) 4-propylguaiacol was used as a model substance for the reaction, and the obtained data are shown in the following table;

[0048]

[0049] Reaction conditions: 4-propylguaiacol (166 mg), catalyst Ru 1 / CeO 2 -X (30 mg), solvent (n-octane 3 ml), initial hydrogen pressure (3 MPa), 120 ° C, 4 h, 600 r / min;

[0050]

[0051] (2) Based on the reaction of real lignin oil, the data obtained are shown in Figure 4 .

[0052] It can be seen from the figure that the aromatic region in the green box almost completely disappears, confirming the ability of the catalyst to saturate the aromatics of lignin oil. The methoxy region in the purple box is retained, indicating that the catalyst can inhibit the breakage of the CO bond and show good performance in generating bio-based cyclohexanediol monomethyl ether.

[0053] Comparative Example 1:

[0054] Conventional single-atom C-Ru 1 / CeO 2 -X Catalyst Preparation Method (with prefix C to indicate conventional)

[0055] Raw materials include CeO 2 -X 50mg, and test 50mg of CeO 2 -X can absorb how many microliters of water (set as x), prepare x microliters of ruthenium trichloride aqueous solution, in which the metal Ru content is about 0.25mg. 2 -X, evaporate the water using a rotary evaporator and heat in a tube furnace. 2 Reduction at 600℃ for 3h in atmosphere to obtain C-Ru 1 / CeO2 -X.

[0056] Comparative Example 2:

[0057] Nanocluster Ru / CeO 2 -X catalyst preparation method

[0058] Raw materials include CeO 2 -X 50mg, hydrated ruthenium trichloride 2mg, deionized water 30ml.

[0059] 50 mg of CeO 2 -X was dispersed in 20 ml of deionized water, and ruthenium chloride aqueous solution (10 ml) was added dropwise to CeO 2 -X dispersion, 1M ammonia was added to adjust the solution pH to 10, and after vigorous stirring for 6 hours, the solid was centrifuged and washed 5 times with deionized water, dried at 60°C in a vacuum furnace, and reduced at 600°C in a hydrogen atmosphere for 3 hours to obtain CeO 2 -X supported Ru nanoparticle catalyst Ru / CeO 2 -X.

[0060] Comparative Example 3:

[0061] Non-precious metal M (Ni, Co, Cu) single atom M 1 / CeO 2 -X catalyst preparation method

[0062] Take 50 mg CeO 2 -X was dispersed in 20 ml of deionized water, and 3 mg of nickel nitrate hexahydrate, cobalt nitrate hexahydrate or copper nitrate trihydrate was dissolved in 10 ml of deionized water. The nickel nitrate, cobalt nitrate or copper nitrate aqueous solution was added dropwise to CeO 2 -X aqueous solution, vigorously stirred at 600 rpm for 6 h, centrifuged, washed with deionized water 5 times, dried in vacuum at 60 °C, and then heated in a tube furnace for 1 0.5 h. 2 At 600℃ for 3h, M 1 / CeO 2 -X(M=Ni, Co, Cu).

[0063] Experimental example

[0064]

[0065] discuss:

[0066] Ru 1 / CeO 2 - Reasons for high X activity:

[0067] 1. Non-precious metal M (Ni, Co, Cu) and carrier CeO2 The interaction is weak, and the formed MO-Ce bond cannot activate the aromatic hydrocarbons of the substrate to saturate it at the experimental temperature;

[0068] 2. Ru / CeO formed by Ru nanoparticles 2 -X, most of them exist in the form of Ru-Ru bonds, which have weak ability to activate aromatic hydrocarbons and low atomic utilization rate; in addition, the presence of Ru nanoparticles cannot promote the formation of CeO 2 More oxygen vacancies are formed;

[0069] 3. C-Ru 1 / CeO 2 -X series catalysts have uneven dispersion of Ru atoms, and Ru exists in the catalyst in a single-atom state. The loading amount of Ru needs to be reduced. Transitionally dispersed single-atom Ru will affect the adsorption of substrates on active sites, thereby affecting the reaction activity.

[0070] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for preparing a highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether, characterized in that: The steps include: 1) Prepare the raw materials according to the following proportions to prepare the carrier CeO2-X: 1.737 g of cerous nitrate hexahydrate, 0.01-1 g of trisodium phosphate, and 5-50 ml of deionized water; 1.737 g of cerous nitrate hexahydrate is added to deionized water, and fully dissolved at a speed of 600 rpm to obtain a solution, and 0.01-1 g of trisodium phosphate is added to the solution, and the mixture is mixed in any proportion; after stirring at room temperature for 30 minutes, the solution is transferred to an autoclave equipped with a polytetrafluoroethylene liner and placed in a constant temperature drying oven, and heated at a constant temperature of 150-250° C. for 5-30 hours. After cooling to room temperature, the solid-liquid mixture is centrifuged, the solid is taken out, and the remaining solid is fully washed with deionized water for 3-8 times, and after vacuum drying at 60° C., it is calcined in air at 500° C. for 3 hours to obtain CeO2-X, wherein X is O, representing an octahedron; 2) Take 50mg CeO2 and disperse it in 20ml deionized water, then take 1-10mg hydrated ruthenium chloride and dissolve it in 10ml deionized water, add the ruthenium chloride aqueous solution dropwise to the CeO2 dispersion, stir vigorously for 6h at a speed of 300-800rpm, centrifuge, and wash with deionized water 3-8 times, dry in vacuum at 60℃, and then reduce at 600℃ in a tube furnace under H2 atmosphere for 3h to obtain a highly active single-atom catalyst for the synthesis of bio-based cyclohexanediol monomethyl ether, referred to as Ru1 / CeO2-X catalyst The Ru1 / CeO2-X catalyst exposes the (111) crystal plane of CeO2; the single grain size of the Ru1 / CeO2-X catalyst is 50-200nm; the mass loading of Ru in the Ru1 / CeO2-X catalyst is 0.3-0.8%, and no Ru nanoparticles appear in the Ru1 / CeO2-X catalyst; in the process of synthesizing bio-based cyclohexanediol monomethyl ether, the catalyst uses lignin-derived phenol as a raw material, and the selectivity of bio-based cyclohexanediol monomethyl ether is greater than 95%.

2. A highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether, characterized in that: The preparation method of the highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether described in claim 1 is obtained, wherein the Ru1 / CeO2-X catalyst exposes the (111) crystal plane of CeO2; the single grain size of the Ru1 / CeO2-X catalyst is 50-200nm; the mass loading amount of Ru in the Ru1 / CeO2-X catalyst is 0.3-0.8%, and no Ru nanoparticles appear in the Ru1 / CeO2-X catalyst; in the process of synthesizing bio-based cyclohexanediol monomethyl ether, the catalyst uses lignin-derived phenol as raw material, and the selectivity of bio-based cyclohexanediol monomethyl ether is greater than 95%.

3. The use of a highly active single-atom catalyst for synthesizing bio-based cyclohexanediol monomethyl ether according to claim 2, characterized in that: The steps include: 1) Prepare the raw materials according to the following ratio: 100-500 mg of lignin-derived phenol, 5-20 mg of Ru1 / CeO2-X catalyst, and 3 ml of n-octane; 2) Carry out saturation reaction of lignin-derived phenol: add lignin-derived phenol and Ru1 / CeO2-X catalyst into a high-pressure reactor, add solvent n-octane, fill with hydrogen, reaction conditions: room temperature to 120°C, reaction time 1-4h, reaction pressure 0.5-4.0MPa, to complete the catalytic reaction.

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