Au-based supported catalyst, preparation method and application thereof, and method for preparing corresponding unsaturated alcohol by hydrogenation of pi-pi conjugated aldehyde

Abstract

The invention relates to the technical field of catalytic hydrogenation, in particular to an Au-based supported catalyst and a preparation method and application thereof, and discloses a method for preparing corresponding unsaturated alcohol through pi-pi conjugated aldehyde hydrogenation. The preparation method comprises the following steps: mixing a mixture containing a carrier and a soluble gold compound with an alkaline solution containing a precipitator, regulating the pH value to 6-14, and sequentially carrying out standing, first drying, first roasting and reduction on the obtained mixed slurry to obtain the Au-based supported catalyst, wherein in the alkaline solution, the precipitator is selected from at least one of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide. The Au-based supported catalyst provided by the invention is used for preparing corresponding unsaturated alcohol through pi-pi conjugated aldehyde hydrogenation, and the selectivity of a target product is effectively improved under relatively mild conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic hydrogenation, and in particular to a method for preparing an Au-based supported catalyst, an Au-based supported catalyst prepared by the preparation method, an application of the Au-based supported catalyst, and a method for preparing corresponding unsaturated alcohols by hydrogenating π-π conjugated aldehydes. Background Art

[0002] Unsaturated alcohols, such as aromatic alcohols and enols, are important compounds in organic synthesis and the chemical industry, with widespread applications in medicine, cosmetics, fragrances, coatings, rubber, and fuel. Aromatic alcohols and enols can be extracted from plants and microorganisms or synthesized synthetically. Industrially, hydrogenation of aromatic aldehydes or enals is often used to prepare the corresponding unsaturated alcohols. The selective hydrogenation of π-π conjugated aromatic aldehydes or enals is a crucial element in organic synthesis and industrial catalysis. Due to the conjugation effect between the aromatic ring and the C=O double bond, or between the C=C double bond and the C=O double bond, the electron cloud shifts toward the oxygen radical, making overhydrogenation highly likely during the reduction process. This aldehyde hydrogenation reaction to produce unsaturated alcohols places high demands on both reaction conditions and catalysts.

[0003] Currently, the research on catalysts for the hydrogenation of π-π conjugated aldehydes mainly focuses on active metals. Typical metal catalytic systems include precious metal catalytic systems, non-precious metal catalytic systems and bimetallic / multimetallic synergistic catalytic systems.

[0004] Existing technical research shows that Au 0 It has good selectivity for unsaturated alcohols and can suppress the production of by-products [Ohyama J, Esaki A, Yamamoto Y, et al. RSC Adv., 2013, 3(4): 1033-1036.], and suitable carriers and preparation methods can provide metal precursors with higher dispersion and stability, but the actual loading of Au is usually only (55-70)% of the theoretical value, and the reaction process often requires high temperature or high pressure conditions. At the same time, CN1259131C discloses a new method for preparing a supported nano-gold catalyst, which uses KOH solution to adjust the pH of the impregnation solution to 7-9, and then loads Au on Al2O3 by an equal volume impregnation method. After impregnation, the catalyst needs to be soaked in concentrated ammonia water. Although a 98% Au loading rate is obtained, the catalyst Au particles prepared by this method are large and the dispersion is not high. Summary of the Invention

[0005] The present invention aims to overcome the problems of low Au loading rate, large Au particle size and low Au dispersion in existing Au / γ-Al2O3 catalysts, as well as harsh reaction conditions and complex reaction processes in preparation methods. The present invention provides a preparation method of an Au-based supported catalyst, an Au-based supported catalyst prepared by the preparation method, an application of the Au-based supported catalyst, and a method for preparing corresponding unsaturated alcohols by hydrogenating π-π conjugated aldehydes. The preparation method optimizes the Au loading rate, Au particle size and Au dispersion in the Au-based supported catalyst by regulating the type of precipitant and the pH range. At the same time, the preparation method simplifies the process flow and is convenient for industrial production.

[0006] To achieve the above-mentioned object, the present invention provides a method for preparing an Au-based supported catalyst in a first aspect. The method comprises: mixing a mixture containing a support and a soluble gold compound with an alkaline solution containing a precipitant under stirring and adjusting the pH to 6-14; and sequentially subjecting the obtained mixed slurry to standing, a first drying, a first calcination, and a reduction to obtain an Au-based supported catalyst.

[0007] Wherein, in the alkaline solution, the precipitant is selected from at least one of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0008] Preferably, when the precipitant in the alkaline solution is selected from sodium hydroxide and sodium carbonate in a mass ratio of 1:0.5-1.5, the pH is adjusted to 9-14, preferably 10-12, and more preferably 10.5-11.5.

[0009] The second aspect of the present invention provides an Au-based supported catalyst prepared by the preparation method provided in the first aspect.

[0010] The third aspect of the present invention provides an application of the Au-based supported catalyst provided in the second aspect in the hydrogenation of π-π conjugated aldehydes to prepare corresponding unsaturated alcohols, oxidation of aldehydes and alcohols, and hydrogenation of nitroaromatics.

[0011] A fourth aspect of the present invention provides a method for preparing a corresponding unsaturated alcohol by hydrogenating a π-π conjugated aldehyde, the method comprising: contacting the π-π conjugated aldehyde with a catalyst in the presence of a solvent and hydrogen and reacting to obtain the corresponding unsaturated alcohol;

[0012] Wherein, the catalyst is selected from the Au-based supported catalyst prepared by the preparation method provided by the first aspect.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] (1) The present invention adopts a precipitation deposition method, specifically, mixing the mixture with an alkaline solution under stirring conditions, and regulating the pH by combining the type of precipitant in the alkaline solution. In particular, by regulating the precipitant and pH, the Au loading rate, Au particle size and Au dispersion in the Au-based supported catalyst are effectively regulated, thereby improving the stability and catalytic activity of the Au-based supported catalyst. At the same time, the preparation method provided by the present invention simplifies the process conditions and is convenient for industrial production.

[0015] (2) The Au-based supported catalyst provided by the present invention is used for hydrogenation of π-π conjugated aldehydes to prepare corresponding unsaturated alcohols, effectively improving the selectivity of the target product under relatively mild conditions, that is, making the selectivity of the corresponding unsaturated alcohol high, especially up to 98.7%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a TEM image of the Au-based supported catalyst S13 prepared in Example 13;

[0017] Figure 2 This is the TEM image of the Au-based supported catalyst DS1 prepared in Comparative Example 1. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] In the present invention, unless otherwise specified, the terms "first" and "second" do not indicate a sequential order or limit the materials or steps. They are used only to distinguish or indicate that they are not the same materials or steps. For example, the terms "first" and "second" in "first roasting" and "second roasting" are used only to indicate that they are not the same roasting.

[0020] A first aspect of the present invention provides a method for preparing an Au-based supported catalyst, comprising: mixing a mixture containing a support and a soluble gold compound with an alkaline solution containing a precipitant under stirring and adjusting the pH to 6-14; and sequentially subjecting the obtained mixed slurry to standing, a first drying, a first calcination, and a reduction to obtain an Au-based supported catalyst;

[0021] Wherein, in the alkaline solution, the precipitant is selected from at least one of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0022] In some embodiments of the present invention, preferably, the mass ratio of the soluble gold compound calculated as Au to the carrier is 0.1-10:90-99.9, for example, 0.1:99.9, 0.5:99.5, 1:99, 1.5:98.5, 2:98, 3:97, 5:95, 8:92, 10:90, and any value in the range consisting of any two values, preferably 0.5-5:95-99.5, more preferably 1-2:98-99.

[0023] In the present invention, unless otherwise specified, the soluble gold compound refers to a soluble compound containing gold; the soluble compound refers to a compound that is easily soluble in water, or is easily soluble in water under the action of an additive.

[0024] In some embodiments of the present invention, preferably, the soluble gold compound is selected from at least one of HAuCl4·4H2O, HAuCl4·3H2O, Au(en)2Cl3 and Na3Au(S2O3)2.

[0025] In the present invention, the type of the carrier has a wide range of choices. Preferably, the carrier is selected from at least one of γ-Al2O3, SiO2, TiO2, MgO and hydrotalcite, preferably γ-Al2O3.

[0026] In some embodiments of the present invention, further preferably, the carrier is prepared by the following method: an aluminum-containing compound, a binder, an acid and water are mixed, and the obtained mixture is sequentially extruded, dried, calcined and sieved to obtain γ-Al2O3 as the carrier.

[0027] In a specific embodiment of the present invention, the aluminum-containing compound includes but is not limited to alumina, pseudo-boehmite, aluminum hydroxide, etc.; the binder includes but is not limited to sesbania powder, etc.; the acid includes but is not limited to concentrated nitric acid, concentrated sulfuric acid, etc.; the water includes but is not limited to deionized water, etc.

[0028] In a specific embodiment of the present invention, the mass ratio of the aluminum-containing compound, binder, acid and water calculated as Al2O3 is 500:20-50:15-30:250-350; the conditions for the second drying include: temperature of 90-150°C, preferably 100-120°C; time of 10-40h, preferably 12-20h; the conditions for the second calcination include: temperature of 400-800°C, preferably 500-700°C; time of 5-15h, preferably 5-10h.

[0029] In the present invention, the screening is intended to control the average particle size of γ-Al2O3. Preferably, the average particle size of γ-Al2O3 is 10-20 mesh, i.e., 0.85-2 mm.

[0030] The inventors of the present invention have found that by regulating the type of precipitant in the alkaline solution and the pH of the impregnation solution, the Au loading rate, Au dispersion and Au particle size in the Au-based supported catalyst can be effectively regulated.

[0031] In some embodiments of the present invention, preferably, in the alkaline solution, the precipitant is selected from any two of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide, and the mass ratio of the two precipitants is 1:0.1-2, for example, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, and any value in the range consisting of any two values, preferably 1:0.5-1.5.

[0032] In some embodiments of the present invention, preferably, the concentration of the precipitant in the alkaline solution is 5-30 wt %. In the present invention, the solvent of the alkaline solution is water, preferably deionized water.

[0033] In some embodiments of the present invention, the pH is regulated to be 6-14, for example, 6, 8, 9, 10, 10.5, 11, 11.5, 12, 14, and any value in the range consisting of any two values, preferably 9-14, more preferably 10-12, more preferably 10.5-11.5, and most preferably 11.

[0034] In some embodiments of the present invention, preferably, the stirring conditions include: a rotation speed of 50-500 rpm, preferably 100-200 rpm; and a temperature of 20-80°C, preferably 40-60°C.

[0035] In some embodiments of the present invention, preferably, the standing conditions include: a temperature of 20-80° C., preferably 40-60° C.; and a time of 2-12 h, preferably 6-10 h.

[0036] In some embodiments of the present invention, preferably, the first drying conditions include: a temperature of 60-150° C., preferably 90-120° C.; and a time of 6-24 h, preferably 9-12 h.

[0037] In some embodiments of the present invention, preferably, the conditions for the first calcination include: a temperature of 200-700° C., preferably 300-500° C.; and a time of 1-10 h, preferably 1-5 h.

[0038] In some embodiments of the present invention, preferably, the reduction conditions include: temperature of 200-700° C., preferably 300-500° C.; time of 1-10 h, preferably 1-5 h.

[0039] In some embodiments of the present invention, the reduction is preferably carried out in a hydrogen-containing atmosphere, wherein the flow volume ratio of hydrogen to inert gas in the hydrogen-containing atmosphere is 1:0-10, for example, 1:0, 1:1, 1:2, 1:5, 1:8, 1:10, and any value in a range consisting of any two values, preferably 1:2-10. In the present invention, when the flow volume ratio of hydrogen to inert gas in the hydrogen-containing atmosphere is 1:0, it means that the hydrogen-containing atmosphere is a pure hydrogen atmosphere; inert gases include but are not limited to nitrogen, helium, argon, neon, etc., and are preferably nitrogen.

[0040] In some embodiments of the present invention, preferably, the method comprises the following steps:

[0041] (1) dissolving the soluble gold compound in water and then mixing it with the carrier to obtain the mixture; dissolving the precipitant in water to obtain the alkaline solution;

[0042] (2) mixing the mixture with an alkaline solution under stirring and adjusting the pH to 6-14 to obtain the mixed slurry;

[0043] (3) subjecting the mixed slurry to the aforementioned standing, first drying, and first calcination in sequence to obtain an intermediate product;

[0044] (4) In a hydrogen-containing atmosphere, reducing the intermediate product to obtain the Au-based supported catalyst.

[0045] In some embodiments of the present invention, preferably, before the first drying, the static product is filtered and washed in sequence. In the present invention, the filtering method has a wide range of options, as long as solid-liquid separation is achieved.

[0046] In some embodiments of the present invention, further preferably, the washing conditions include: temperature of 20-80°C, preferably 40-60°C; number of times of 3-8 times, preferably 5-6 times; and amount of washing water of 30-70 mL / time.

[0047] In some preferred embodiments of the present invention, preferably, when the precipitant in the alkaline solution is selected from sodium hydroxide and sodium carbonate in a mass ratio of 1:0.1-2, the pH is regulated to be 9-14, for example, 9, 10, 10.5, 11, 11.5, 12, 13, 14, and any value in the range consisting of any two values, preferably 10-12, more preferably 10.5-11.5, and most preferably 11.

[0048] In the present invention, the mass ratio of sodium hydroxide to sodium carbonate in the precipitant is 1:0.1-2, for example, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, or any value in the range of any two numerical values, preferably 1:0.5-1.5, more preferably 1:1, which can more effectively regulate the catalytic activity of the Au-based supported catalyst.

[0049] In the present invention, the above-mentioned precipitant and pH are used to prepare an Au-based supported catalyst having a higher Au loading rate, a higher Au dispersion and a smaller Au particle size, thereby effectively improving the catalytic activity of the Au-based supported catalyst.

[0050] In a preferred embodiment of the present invention, the preparation method of the Au-based supported catalyst comprises the following steps:

[0051] (1) dissolving a soluble gold compound in water and mixing the mixture with γ-Al2O3 as a carrier to obtain a mixture; dissolving a precipitant in water to obtain an alkaline solution; wherein the precipitant is sodium hydroxide and sodium carbonate, and the mass ratio of sodium hydroxide to sodium carbonate is 1:1;

[0052] (2) mixing the mixture with an alkaline solution under stirring and adjusting the pH to 11 to obtain a mixed slurry;

[0053] (3) sequentially allowing the mixed slurry to stand, filter, wash, perform a first drying, and perform a first roasting to obtain an intermediate product;

[0054] (4) Reducing the intermediate product in a hydrogen-containing atmosphere to obtain an Au-based supported catalyst.

[0055] The second aspect of the present invention provides an Au-based supported catalyst prepared by the preparation method provided in the first aspect.

[0056] In some embodiments of the present invention, preferably, based on the total weight of the Au-based supported catalyst, the Au content is 0.1-10wt%, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 3wt%, 5wt%, 8wt%, 10wt%, and any value in the range of any two values, preferably 0.5-5wt%, more preferably 1-2wt%.

[0057] In some embodiments of the present invention, preferably, the Au loading rate in the Au-based supported catalyst is ≥20%, for example, 20%, 22%, 30%, 38%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, 90%, 92%, 95%, 98%, and any value in the range consisting of any two numerical values, preferably ≥60%, more preferably 90-98%; the Au particle size is ≤20 nm, for example, 5 nm, 6 nm, 8 nm, 9 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, and any value in the range consisting of any two numerical values, preferably ≤15 nm, preferably 5-10 nm.

[0058] In the present invention, unless otherwise specified, the loading rate parameter is measured by X-ray fluorescence spectrometry (XRF); and the particle size parameter is measured by transmission electron microscopy (TEM).

[0059] The third aspect of the present invention provides an application of the Au-based supported catalyst provided in the second aspect in the hydrogenation of π-π conjugated aldehydes to prepare corresponding unsaturated alcohols, oxidation of aldehydes and alcohols, and hydrogenation of nitroaromatics.

[0060] A fourth aspect of the present invention provides a method for preparing a corresponding unsaturated alcohol by hydrogenating a π-π conjugated aldehyde, characterized in that the method comprises: contacting the π-π conjugated aldehyde with a catalyst and reacting in the presence of a solvent and hydrogen to obtain the corresponding unsaturated alcohol;

[0061] Wherein, the catalyst is selected from the Au-based supported catalyst prepared by the preparation method provided by the first aspect.

[0062] In some embodiments of the present invention, preferably, the reaction conditions include: temperature of 90-110°C, pressure of 0.5-3 MPa, and time of 2-6 hours. More preferably, the reaction conditions include: temperature of 95-105°C, pressure of 1-2 MPa, and time of 3-6 hours. More preferably, the reaction conditions include: temperature of 100°C, pressure of 2 MPa, and time of 4 hours. In the present invention, all pressure parameters are gauge pressures.

[0063] In the present invention, the reaction is carried out in an autoclave, and the total amount of the π-π conjugated aldehyde and the solvent is 10-50% of the volume of the autoclave. Preferably, the mass ratio of the π-π conjugated aldehyde and the solvent is 1:4-19, for example, 1:4, 1:5, 1:8, 1:10, 1:15, 1:19, and any value in the range consisting of any two values.

[0064] In some embodiments of the present invention, preferably, the π-π conjugated aldehyde is selected from aromatic aldehydes and / or alkenals; further preferably, the π-π conjugated aldehyde is selected from at least one of 5-hydroxymethylfurfural, furfural, benzaldehyde and acrolein.

[0065] In a specific embodiment of the present invention, when the π-π conjugated aldehyde is selected from 5-hydroxymethylfurfural, the corresponding unsaturated alcohol is 5-hydroxymethylfurfural; when the π-π conjugated aldehyde is selected from furfural, the corresponding unsaturated alcohol is furfuryl alcohol; when the π-π conjugated aldehyde is selected from benzaldehyde, the corresponding unsaturated alcohol is benzyl alcohol; when the π-π conjugated aldehyde is selected from acrolein, the corresponding unsaturated alcohol is allyl alcohol.

[0066] In some embodiments of the present invention, preferably, the solvent is selected from water and an organic solvent, and the organic solvent is selected from at least one of methanol, ethanol, acetonitrile and methyl isobutyl ketone; further preferably, the solvent is selected from water, methanol and / or ethanol.

[0067] In some embodiments of the present invention, preferably, the mass ratio of the π-π conjugated aldehyde and the catalyst is 1:0.1-1, for example, 1:0.1, 1:0.2, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.8, 1:1, and any value in the range consisting of any two values, preferably 1:0.4-0.6, more preferably 1:0.5.

[0068] According to a particularly preferred embodiment of the present invention, a method for preparing a corresponding unsaturated alcohol by hydrogenating a π-π conjugated aldehyde comprises: contacting the π-π conjugated aldehyde with a catalyst and reacting the π-π conjugated aldehyde in the presence of a solvent and hydrogen to obtain the corresponding unsaturated alcohol;

[0069] The catalyst is selected from an Au-based supported catalyst, and the Au-based supported catalyst is prepared by the following method: (1) dissolving a soluble gold compound in water and then mixing it with γ-Al2O3 as a carrier to obtain a mixture; dissolving a precipitant in water to obtain an alkaline solution; wherein the precipitant is sodium hydroxide and sodium carbonate, and the mass ratio of sodium hydroxide to sodium carbonate is 1:1; (2) mixing the mixture and the alkaline solution under stirring and adjusting the pH to 11 to obtain a mixed slurry; (3) sequentially allowing the mixed slurry to stand, filter, wash, first dry, and first roast to obtain an intermediate product; (4) reducing the intermediate product in a hydrogen-containing atmosphere to obtain an Au-based supported catalyst;

[0070] The reaction conditions include: temperature of 95-105° C.; pressure of 1-2 MPa; time of 3-6 hours; rotation speed of 400-500 rpm; and the π-π conjugated aldehyde is selected from at least one of 5-hydroxymethylfurfural, furfural, benzaldehyde and acrolein.

[0071] The present invention will be described in detail below through examples.

[0072] Preparation of γ-Al2O3 carrier: Weigh 500.00g of alumina powder and 25.71g of sesbania powder in a beaker, stir evenly with a glass rod, then add 300g of deionized water and 15.42g of concentrated nitric acid, stir evenly and extrude into shape. The obtained wet strips are dried at 100°C for 15h, calcined at 600°C for 6h, and then crushed and sieved into particles with a particle size of 1mm to obtain γ-Al2O3 carrier A1.

[0073] Example 1

[0074] (1) Weigh 0.1056 g of HAuCl4·4H2O and dissolve it in 20.00 g of deionized water to obtain an AuCl3 solution. Then, add 5.00 g of the γ-Al2O3 carrier A1 to the AuCl3 solution to obtain a mixture.

[0075] Weigh 0.40 g of Na2CO3 and dissolve it in 9.00 g of deionized water to obtain an alkaline solution;

[0076] (2) under stirring conditions (rotation speed of 150 rpm, temperature of 40 ± 2.0 ° C), the alkaline solution was added dropwise to the mixture, and the pH of the solution was adjusted to 9 to obtain a mixed slurry;

[0077] (3) The mixed slurry was allowed to stand at 40°C for 4 hours, filtered with a funnel, washed with 200 mL of deionized water 6 times, dried at 100°C for 12 hours, and calcined at 300°C for 3 hours to obtain an intermediate product;

[0078] (4) The intermediate product was reduced at 300°C for 3 h under a flow rate of 20 mL / min H2 and 100 mL / min N2 to obtain Au-based supported catalyst S1.

[0079] Examples 2-4

[0080] The method of Example 1 is as follows, except that

[0081] In step (1), 0.40 g of Na2CO3 in the alkaline solution was replaced with 1.0 g of KHCO3, 0.40 g of NaOH and 0.40 g of 25 wt% concentrated ammonia solution;

[0082] The other conditions were the same, and Au-based supported catalysts S2-S4 were obtained respectively.

[0083] Examples 5-7

[0084] According to the method of Example 1, the difference is that

[0085] In step (1), 0.40 g of Na2CO3 in the alkaline solution was replaced by 0.20 g of KHCO3 and 0.20 g of NaOH, 0.20 g of Na2CO3 and 0.20 g of NaOH, and 0.20 g of concentrated ammonia and 0.20 g of NaOH, respectively;

[0086] The other conditions were the same, and Au-based supported catalysts S5-S7 were obtained respectively.

[0087] Examples 8-9

[0088] According to the method of Example 1, the difference is that

[0089] In step (1), 0.40 g of Na2CO3 in the alkaline solution was replaced by 0.13 g of Na2CO3 and 0.27 g of NaOH, and 0.27 g of Na2CO3 and 0.13 g of NaOH, respectively;

[0090] The other conditions were the same, and Au-based supported catalysts S8-S9 were obtained respectively.

[0091] Examples 10-15

[0092] According to the method of Example 1, the difference is that

[0093] In step (1), 0.40 g of Na2CO3 in the alkaline solution was replaced with 1.0 g of Na2CO3 and 1.0 g of NaOH;

[0094] In step (2), the pH is adjusted to 6, 8, 10, 11, 12 and 14 respectively;

[0095] The other conditions were the same, and Au-based supported catalysts S10-S15 were obtained respectively.

[0096] The TEM image of the Au-based supported catalyst S13 is shown in FIG. Figure 1 As shown by Figure 1 It can be seen that the Au-based supported catalyst S13 has a larger Au dispersion and a smaller Au particle size, that is, the Au particle size is 6.05 nm.

[0097] Comparative Example 1

[0098] According to the method of CN1259131C, 0.1056 g of HAuCl4·4H2O was weighed and dissolved in 5.12 g of deionized water. The pH was adjusted to 7.5 with 1.13 mL of 1 mol / L potassium hydroxide solution. 5.00 g of the above-mentioned γ-Al2O3 carrier A1 was weighed and poured into the above solution for impregnation. After appropriate stirring, it was allowed to stand for 1 hour and then soaked in 40 mL of ammonia water with a pH of 11 for 10 minutes. The mixture was filtered with a funnel and washed with 200 mL of deionized water six times. The mixture was dried at 60°C for 12 hours, calcined at 300°C for 3 hours, and reduced at 300°C for 3 hours under a flow rate of 20 mL / min H2 and 100 mL / min N2 to obtain the Au-based supported catalyst DS1.

[0099] The TEM image of the Au-based supported catalyst DS1 is shown in FIG. Figure 2 As shown by Figure 2 It can be seen that compared with the Au-based supported catalyst S13 prepared in Example 13, the Au-based supported catalyst DS1 has a smaller Au dispersion and a larger Au particle size.

[0100] Table 1

[0101]

[0102]

[0103] Note: Au content in Au-based supported catalyst = Au theoretical content × Au loading rate. For example, in Example 1, in Au-based supported catalyst S1, Au content = 1 wt% (Au theoretical content) × 38% (Au loading rate) = 0.38 wt%.

[0104] Test Example 1

[0105] In an 80 mL autoclave, 0.3 g of the Au-based supported catalysts (S1-S15 and DS1) prepared in the above examples and comparative examples were added, followed by 0.60 g of 5-hydroxymethylfurfural and 8.40 g of deionized water, which were then mixed. After the autoclave was installed, 2.0 MPa of hydrogen was introduced into the autoclave, the reaction temperature was set at 100° C., the stirring rate was set at 500 rpm, and the reaction time was 4 h. After the reaction was completed and the system was cooled to room temperature, the exhaust was carried out, and the reactor was disassembled. The product was sampled and analyzed by gas chromatography. The test results are listed in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] It can be seen from the data in Table 1-2 that, compared with Comparative Example 1, the Au-based supported catalysts prepared by the preparation method provided by the present invention in Examples 1-15 are used for hydrogenation of 5-hydroxymethylfurfural to prepare the corresponding unsaturated alcohols. Under the same reaction conditions, the Au-based supported catalysts provided by the present invention have a high Au loading rate, a high Au dispersion and a low Au particle size, thereby obtaining a highly selective target product.

[0110] Comparing Examples 1-4, it can be seen that the selectivity of the target product of the Au-based supported catalysts prepared using a single type of precipitant in catalyzing the hydrogenation of 5-hydroxymethylfurfural is similar, but the conversion rate of the raw material varies greatly. Among them, the most active is the Au-based supported catalyst S3 prepared using NaOH as the precipitant. At the same time, compared with Example 3 using NaOH, Example 1 uses Na2CO3 as the precipitant. Since Na2CO3 is a weak base, the resulting precipitate contains carbonate, which is difficult to remove and interacts with Au, affecting the particle size and activity, and thus affecting the catalytic activity; Example 4 uses ammonia water as the precipitant. Heating ammonia ions will form ammonia gas that volatilizes, so the Au loading rate is slightly higher than that of Example 1, and the Au particle size is smaller than that of Example 1.

[0111] Comparison of Examples 5-7 reveals that, when catalyzing the hydrogenation of 5-hydroxymethylfurfural, the Au-supported catalyst S6, prepared using NaCO and NaOH as precipitants, exhibits the highest catalytic activity among the Au-supported catalysts prepared using the two precipitants. This is likely due to the mixing with a strong base, which allows for achieving the target pH, requiring a smaller amount of NaCO, and the presence of a small amount of carbonate ions, which has a minimal effect on Au particle size and can act as acidic sites for H activation.

[0112] By comparing Example 1, Example 3, Example 6 and Examples 8-9, it can be seen that when the Au-based supported catalysts prepared using two precipitants in different mass ratios catalyze the hydrogenation of 5-hydroxymethylfurfural, the Au-based supported catalyst S6 prepared using Na2CO3 and NaOH in a mass ratio of 1:1 as precipitants has the highest catalytic activity.

[0113] Comparison of Examples 10-15 shows that when Au-based supported catalysts prepared at different pH values ​​are used to catalyze the hydrogenation of 5-hydroxymethylfurfural, the Au-based supported catalyst S13 prepared at pH=11 has the highest catalytic activity.

[0114] Test Example 2

[0115] In an 80 mL autoclave, 0.3 g of the Au-based supported catalyst S13 prepared in Example 13 above and 8.4 g of deionized water were added, followed by 0.60 g of benzaldehyde, 0.60 g of furfural, and 0.60 g of acrolein, respectively, and mixed uniformly. After the autoclave was installed, 2 MPa of hydrogen was introduced into the autoclave, the reaction temperature was set to 100° C., the stirring rate was set to 500 rpm, and the reaction time was set to 4 h. After the reaction was completed and the system was cooled to room temperature, the air was vented, and the reactor was disassembled. The product was sampled and analyzed by gas chromatography. The test results are listed in Table 3.

[0116] Table 3

[0117]

[0118] The data in Table 3 show that when the Au-based supported catalyst S13 provided by the present invention is used to catalyze the hydrogenation of different types of π-π conjugated aldehydes, the corresponding unsaturated alcohols can be obtained with a selectivity of more than 90% under relatively mild reaction conditions.

[0119] Test Example 3

[0120] In an 80 mL autoclave, 0.3 g of the Au-based supported catalyst S13 prepared in Example 13 above was added, followed by 0.60 g of 5-hydroxymethylfurfural and 8.40 g of deionized water, and the mixture was uniformly mixed. After the autoclave was installed, the hydrogen gas charged into the autoclave was set according to the data in Table 4 for the reaction temperature, stirring rate, reaction time, and reaction pressure. After the reaction was completed and the system was cooled to room temperature, the system was vented and the reactor was disassembled. The product was sampled and analyzed by gas chromatography. The test results are listed in Table 4.

[0121] Table 4

[0122]

[0123] As can be seen from the data in Table 4, the Au-based supported catalyst provided by the present invention is used for the hydrogenation catalysis of π-π conjugated aldehydes, especially 5-hydroxymethylfurfural, combined with the reaction conditions, reaction temperature and reaction pressure defined in the present invention, while ensuring a high raw material conversion rate, the selectivity of the target product is improved.

[0124] At the same time, based on the data in Table 4, it can be seen that as the reaction temperature increases, the feedstock conversion rate and target product selectivity increase; however, excessively high reaction temperatures can lead to excessive hydrogenation, resulting in reduced target product selectivity. Therefore, low temperatures (<95°C), low pressures (<1MPa), and high pressures (>3MPa) may lead to reduced feedstock conversion rates, while high temperatures (>105°C) can lead to reduced target product selectivity.

[0125] Test Example 4

[0126] In an 80 mL autoclave, 0.3 g of the Au-based supported catalyst S13 prepared in Example 13 above was added, along with 0.60 g of 5-hydroxymethylfurfural and 8.40 g of methanol, and the mixture was mixed thoroughly. After the autoclave was installed, 2 MPa of hydrogen was introduced into the autoclave, the reaction temperature was set to 100°C, the stirring rate was set to 500 rpm, and the reaction time was set to 4 h. After the reaction was completed and the system was cooled to room temperature, the air was vented and the reactor was disassembled. The product was sampled and analyzed by gas chromatography. The catalyst was removed, washed with methanol, and dried at 60°C for 6 h. The dried catalyst was reused four times according to the above procedures. The test results are listed in Table 5.

[0127] Table 5

[0128] Number of cycles Raw material conversion rate, % Selectivity of target product, % 1 94.5 98.7 2 92.8 97.5 3 92.5 95.6 4 90.6 95.3 5 90.2 93.2

[0129] It can be seen from the data in Table 5 that the Au-based supported catalyst provided by the present invention has no obvious activity loss after being reused 5 times, and has good stability.

[0130] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing an Au-based supported catalyst, characterized in that: The preparation method comprises: mixing a mixture containing a carrier and a soluble gold compound with an alkaline solution containing a precipitant under stirring conditions and adjusting the pH to 6-14; and sequentially subjecting the obtained mixed slurry to standing, first drying, first calcining, and reduction to obtain an Au-based supported catalyst; Wherein, in the alkaline solution, the precipitant is selected from at least one of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide.

2. The preparation method according to claim 1, wherein The mass ratio of the soluble gold compound calculated as Au to the carrier is 0.1-10:90-99.9, preferably 0.5-5:95-99.5, more preferably 1-2:98-99; Preferably, the soluble gold compound is selected from at least one of HAuCl4·4H2O, HAuCl4·3H2O, Au(en)2Cl3 and Na3Au(S2O3)2; Preferably, the carrier is selected from at least one of γ-Al2O3, SiO2, TiO2, MgO and hydrotalcite, preferably γ-Al2O3; Further preferably, the carrier is prepared by the following method: mixing an aluminum-containing compound, a binder, an acid and water, and sequentially extruding, second drying, second calcining and screening the obtained mixture to obtain γ-Al2O3 as the carrier; Preferably, in the alkaline solution, the precipitant is selected from any two of ammonia water, potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide, and the mass ratio of the two precipitants is 1:0.1-2, preferably 1:0.5-1.5; Preferably, the concentration of the precipitant in the alkaline solution is 5-30 wt%.

3. The preparation method according to claim 1 or 2, wherein Regulating the pH to 9-14, preferably 10-12, more preferably 10.5-11.5; Preferably, the stirring conditions include: a rotation speed of 50-500 rpm, preferably 100-200 rpm; a temperature of 20-80° C., preferably 40-60° C.; Preferably, the standing conditions include: temperature of 20-80°C, preferably 40-60°C; time of 2-12 hours, preferably 6-10 hours; Preferably, the first drying conditions include: temperature of 60-150°C, preferably 90-120°C; time of 6-24h, preferably 9-12h; Preferably, the conditions for the first calcination and reduction are independently as follows: temperature of 200-700°C, preferably 300-500°C; time of 1-10h, preferably 1-5h; Preferably, the reduction is carried out in a hydrogen-containing atmosphere, and the flow volume ratio of hydrogen to inert gas in the hydrogen-containing atmosphere is 1:0-10, preferably 1:2-10.

4. The preparation method according to any one of claims 1 to 3, wherein The method comprises the following steps: (1) dissolving the soluble gold compound in water and then mixing it with the carrier to obtain the mixture; dissolving the precipitant in water to obtain the alkaline solution; (2) mixing the mixture with an alkaline solution under stirring and adjusting the pH to 6-14 to obtain the mixed slurry; (3) subjecting the mixed slurry to the aforementioned standing, first drying, and first calcination in sequence to obtain an intermediate product; (4) reducing the intermediate product in a hydrogen-containing atmosphere to obtain the Au-based supported catalyst; Preferably, before the first drying, the static product is filtered and washed in sequence; Further preferably, the washing conditions include: temperature of 20-80° C., preferably 40-60° C.; number of times of 3-8 times, preferably 5-6 times; and amount of washing water of 30-70 mL / time.

5. The preparation method according to any one of claims 1 to 4, wherein When the precipitant in the alkaline solution is selected from sodium hydroxide and sodium carbonate in a mass ratio of 1:0.1-2, preferably 1:0.5-1.5, the pH is adjusted to 9-14, preferably 10-12, and more preferably 10.5-11.

5.

6. The Au-based supported catalyst prepared by the preparation method according to any one of claims 1 to 5; Preferably, the Au content is 0.1-10 wt %, preferably 0.5-5 wt %, more preferably 1-2 wt %, based on the total weight of the Au-based supported catalyst; Preferably, in the Au-based supported catalyst, the Au loading rate is ≥20%, preferably ≥60%, more preferably 90-98%; the Au particle size is ≤20 nm, preferably ≤15 nm, and preferably 5-10 nm.

7. Use of the Au-based supported catalyst according to claim 6 in the hydrogenation of π-π conjugated aldehydes to prepare corresponding unsaturated alcohols, oxidation of aldehydes and alcohols, and hydrogenation of nitroaromatics.

8. A method for preparing a corresponding unsaturated alcohol by hydrogenating a π-π conjugated aldehyde, characterized in that: The method comprises: in the presence of a solvent and hydrogen, contacting a π-π conjugated aldehyde with a catalyst and reacting the aldehyde to obtain a corresponding unsaturated alcohol; Wherein, the catalyst is selected from the Au-based supported catalyst prepared by the preparation method according to any one of claims 1 to 5.

9. The method according to claim 8, wherein The reaction conditions include: temperature of 90-110° C., preferably 95-105° C.; pressure of 0.5-3 MPa, preferably 1-2 MPa; time of 2-6 h, preferably 3-6 h; rotation speed of 200-700 rpm, preferably 400-500 rpm.

10. The method according to claim 8 or 9, wherein: The π-π conjugated aldehyde is selected from aromatic aldehydes and / or alkenes, preferably at least one selected from 5-hydroxymethylfurfural, furfural, benzaldehyde and acrolein; Preferably, the solvent is selected from water and an organic solvent, and the organic solvent is selected from at least one of methanol, ethanol, acetonitrile and methyl isobutyl ketone; Preferably, the mass ratio of the π-π conjugated aldehyde to the catalyst is 1:0.1-1, preferably 1:0.4-0.6.

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