A doped hydrotalcite-supported Au catalyst, preparation method and use thereof

Abstract

The present invention provides a doped hydrotalcite-supported Au catalyst, a preparation method and uses thereof. The catalyst is a doped composite metal hydroxide-supported Au-metal oxide, wherein the composite metal hydroxide comprises two or three of magnesium hydroxide, boehmite, nickel hydroxide, cobalt hydroxide, copper hydroxide or zinc hydroxide, and the doped element is at least one of Ce, Zr, Ga, Mn, Sn, La, including cerium oxide, zirconium oxide, gallium oxide, manganese oxide, tin oxide, etc.; the metal oxide comprises at least one of nickel oxide, copper oxide, cobalt oxide, iron oxide. The doped hydrotalcite-supported Au catalyst of the present invention catalyzes the preparation of amide compounds from alcohol molecules and amine molecules without the addition of an external base, and the highest yield can reach 97% in 24 h.

Description

Technical Field

[0001] The present invention relates to the fields of chemistry, chemical engineering and catalysts, and particularly relates to a doped hydrotalcite-supported Au catalyst, a preparation method and uses thereof. Background Art

[0002] As an important branch of nitrogen-containing organic compounds, amide compounds have a wide range of applications in many pharmacologically active compounds and materials due to their unique amide bond functional group (-CONH-). At present, amide bonds are also present in 25% of the drugs on the market. For example, atorvastatin, which is used to reduce plasma cholesterol and lipoprotein levels; lisinopril, a drug used to treat various degrees of hypertension and renal hypertension; valsartan, an antihypertensive antagonist, etc. In addition, some lactam rings can be used as organic chemical raw materials for industrial production and are crucial for maintaining the antibacterial activity of some compounds, such as β-lactams, 2-quinolones, etc. Given the very important value of amide compounds, it is of great significance to explore efficient and green synthesis methods for amide compounds.

[0003] Based on the properties and wide applications of amide bonds, more and more studies have been carried out on the synthesis of such compounds. Generally speaking, the method that is currently used more is the condensation of carboxylic acids or carboxylic acid derivatives with amines, which is mainly used industrially. However, carboxylic acid condensation has great limitations, requiring high temperatures and accompanied by hydrolysis. Although using carboxylic acid derivatives is more prone to reaction, there are problems such as high toxicity and low atom economy. In addition, there are some other methods, such as Beckmann rearrangement, Staudinger reaction, amination carbonylation, and alcohol dehydrogenative amidation, etc. Among them, due to the good stability, economy and environmental friendliness of alcohols, their dehydrogenative amidation has great advantages and has been widely studied by chemists.

[0004] At present, there are mainly two types of developed alcohol dehydrogenative amidation: direct dehydrogenative amidation and oxidative dehydrogenative amidation. Most of the direct dehydrogenative amidation of alcohols uses homogeneous complex catalysts and requires the addition of an external base to promote dehydrogenation, mainly suffering from problems such as limited substrates, harsh conditions, and low product selectivity. While alcohol oxidative dehydrogenative amidation has milder reaction conditions and is currently mainly achieved by homogeneous catalysts and supported metal catalysts under the condition of liquid base.

[0005] The homogeneous system mainly involves Cu and Fe active centers participating in alcohol oxidative amidation (J. Am. Chem. Soc., 2016, 138: 6416, Tetrahedron Lett., 2013, 54: 4922), and it is necessary to add a promoter to activate oxygen or add other oxidants to promote oxidative dehydrogenation. However, the nitroso radicals and strong oxidants used in this system are prone to cause side products such as the direct oxidation of alcohols to acids, resulting in low yields.

[0006] Therefore, the multiphase supported metal catalyst has more advantages. In 2001, the Kobayashi team first reported the catalytic alcohol oxidative amidation by cross-linked polystyrene-based polymer immobilized gold nanoparticles (PICB-Au, 2.4 nm), and O 2 participated in the reaction as a green stoichiometric oxidant. Further speculation on the reaction pathway is that the alcohol is first oxidized to form an aldehyde on the Au nanoparticles by the action of an external base, and the amine simultaneously undergoes a nucleophilic attack to form a hemiaminal intermediate, which further undergoes an oxidative dehydrogenation process on the Au nanoparticles to form an amide bond, and an amide yield of 95% was achieved (J. Am. Chem. Soc. 2011, 133, 18550). In addition, other organic polymer supported Au-based catalysts include Au / DNA, Pd / SEP-GO, etc. (Angew. Chem. Int. Ed. 2011, 50, 8917, Catal. Sci. Technol. 2016, 6, 4124), and all of them require the action of a base or hydrogen peroxide to achieve alcohol oxidative amidation. Since the use of organic support-supported catalysts is prone to metal aggregation and loss, resulting in deactivation. Therefore, inorganic support-supported Au-based catalysts have been developed. Hydroxyapatite is used to support Au nanoparticles, and the catalyst structure is improved. After 24 h of reaction, the amide yield reaches 98%, but it has no catalytic activity without adding an external base (Tetrahedron Lett. 2014, 55, 124).

[0007] CN115108976A discloses a method for preparing picolinamide by one-step oxidative amidation. This method uses a V-N-C material as a multiphase catalyst, molecular oxygen as an oxygen source, and in the presence of a nitrogen-containing compound, pyridine methanol / pyridine formaldehyde is directly oxidized to picolinamide in a solvent. The specific steps are as follows: pyridine methanol / pyridine formaldehyde, a V-N-C catalyst, a nitrogen-containing compound, and a solvent are added to a reaction kettle, and then molecular oxygen is introduced as the oxygen source. After sealing the reaction kettle, it is stirred and heated to 60-160 °C, and the reaction time is no more than 12 h. Then it is cooled to room temperature, the pressure is released, and after filtering off the catalyst, picolinamide is separated. Among them, the used V-N-C material catalyst is prepared by mixing a certain proportion of inorganic vanadium compounds and organic amines and then performing heat treatment. The preparation method is as follows: a certain amount of inorganic vanadium compounds and organic amines are mixed, and this mixture is calcined in an inert atmosphere at 300-1000 °C for 0.5-20 h and then cooled to obtain the V-N-C material catalyst. However, the defect of using this catalyst to prepare picolinamide is that the used vanadium has high toxicity, and the reaction substrates pyridine methanol or pyridine formaldehyde are aromatic alcohols, which are prone to oxidation reactions and can only undergo an amidation process with ammonia.

[0008] Therefore, in the absence of an externally added base, developing a more efficient supported metal catalyst for the preparation of amide compounds is an urgent problem to be solved. Summary of the Invention

[0009] To solve the problems of the prior art, the present invention provides a doped hydrotalcite-supported Au catalyst. The doped hydrotalcite-supported Au catalyst uses a doped composite metal hydroxide as a carrier and Au and a metal oxide as active substances. By doping the carrier with metals of different valence states and regulating the contents of these different metals, more oxygen vacancies are provided on the catalyst surface, which is beneficial to the adsorption of alcohol and oxygen substrates, thereby promoting the activation of alcohol and oxygen, and further enhancing the amidation activity. The doped hydrotalcite-supported Au catalyst of the present invention catalyzes the preparation of amide compounds from alcohol molecules and amine molecules under the condition of no externally added base, and the highest yield can reach 97% in 24 h.

[0010] The technical solution of the present invention is as follows:

[0011] The present invention provides a doped hydrotalcite-supported Au catalyst, which is a doped composite metal hydroxide-supported Au-metal oxide. Among them, the composite metal hydroxide contains two or three of magnesium hydroxide, boehmite, nickel hydroxide, cobalt hydroxide, copper hydroxide or zinc hydroxide; the doped element is at least one of Ce, Zr, Ga, Mn, Sn, La, and contains at least one of cerium oxide, zirconium oxide, gallium oxide, manganese oxide, tin oxide; the metal oxide contains at least one of nickel oxide, copper oxide, cobalt oxide, iron oxide.

[0012] Among them, the loading amount of Au is 0.01-3 wt%; and

[0013] The loading amount of the doped element is 0-10 wt%; and

[0014] The loading amount of the metal oxide is 3-10 wt%.

[0015] Furthermore, the catalyst shows obvious characteristic diffraction peaks of hydrotalcite (003), (006), (012), (015), (018), (110), (113) at 11.80°, 23.58°, 34.42°, 38.98°, 46.58°, 60.52°, 61.93°, indicating that the restored catalyst is of hydrotalcite structure. And the characteristic diffraction peaks of the doped metal oxide can be observed from the XRD. It can be seen from the aberration-corrected electron microscope that the particle size of the metal oxide is 5-6 nm, and Au is loaded on the metal oxide, and its particle size is about 2-5 nm.

[0016] The present invention also provides a preparation method of the aforementioned catalyst, and the preparation method includes the following steps:

[0017] Step 1) Preparation of doped composite metal hydroxide

[0018] The doped composite metal hydroxide is formed by subjecting two or more metal nitrates of divalent metal, trivalent metal and doped metal to a precipitation reaction, and the doped composite metal hydroxide includes divalent metal hydroxide, trivalent metal hydroxide and doped metal hydroxide;

[0019] Step 2) Reduction of the doped composite metal hydroxide

[0020] Take the doped composite metal hydroxide for reduction to obtain doped composite oxide supported metal nanoparticles;

[0021] Step 3) Au replacement

[0022] Take the doped composite oxide supported metal nanoparticles, introduce an Au source for replacement to obtain a catalyst precursor, that is, doped composite metal hydroxide supported Au-metal nanoparticles;

[0023] Step 4) Pretreatment and restoration

[0024] Take the catalyst precursor for reduction pretreatment and restoration to obtain a doped composite metal hydroxide supported Au-metal oxide catalyst.

[0025] Further, in step 1), the divalent metal includes at least one of Ni, Co, Cu, Mg, and Zn.

[0026] Further, in step 1), the trivalent metal is composed of one or two of Al and Fe.

[0027] Further, in step 1), the doped metal includes at least one of Ce, Zr, Ga, Mn, Sn, and La.

[0028] Further, in step 1), in the doped composite metal hydroxide, the molar ratio of divalent metal to trivalent metal is (2-4):1; the molar ratio of divalent metal to doped metal is (2-40):1.

[0029] Further, in step 2), the molar ratio of the metal nanoparticles to the divalent metal hydroxide is (0.1-1.5):1. In step 2), a part of the divalent metal hydroxide is reduced into nanoparticles, and the "molar ratio of the metal nanoparticles to the divalent metal hydroxide" here refers to the molar ratio of the metal nanoparticles to the remaining divalent metal hydroxide that has not been converted into metal nanoparticles.

[0030] Further, in step 2), the metal nanoparticles include at least one of Ni, Co, and Cu. Since Mg and Zn cannot be reduced, Mg and Zn are not included in the metal nanoparticles.

[0031] Further, in step 2), a certain amount of the above-mentioned doped composite metal hydroxide is weighed and placed in a tube furnace. Under a hydrogen atmosphere, the temperature is raised to 300-800 °C and maintained for 0-5 h to obtain doped composite oxide-supported metal nanoparticles. In step 2), a part of the divalent metal hydroxide forms metal nanoparticles under a reducing atmosphere.

[0032] Further, in step 2), in the reduction process, the solid powder of the doped composite metal hydroxide is spread flat at the bottom of a porcelain boat, and then the porcelain boat is placed in the central constant-temperature zone of the quartz tube of the tube furnace. After evacuating to vacuum in a closed state with a vacuum pump, a reducing gas is slowly introduced until the pressure value reaches atmospheric pressure. The tube furnace is gradually heated at a heating rate of 1-20 / min. When the temperature of the central constant-temperature zone of the quartz tube reaches 300-800 °C, it is maintained for 0-5 h, and then cooled to room temperature to obtain the doped composite oxide-supported metal nanoparticles.

[0033] Further, in step 3), the doped composite oxide-supported metal nanoparticles are sealed with deoxygenated deionized water and poured into a container. While stirring at 400-1000 revolutions per minute, an aqueous Au solution is added dropwise to the container, and vigorously stirred at room temperature for 5-120 min. In step 3, Au undergoes a displacement reaction and forms on Co, Ni, or Cu; the displacement occurs in an aqueous solution, and the doped composite oxide is partially restored to form a doped composite metal hydroxide.

[0034] Further, in step 3), after the stirring is completed, the solid product is separated, and then the solid product is vacuum-dried at 50-70 °C for 0.1-48 h to obtain the catalyst precursor.

[0035] Further, in step 3), the loading amount of Au is 0.01-3 wt%.

[0036] Further, in step 4), the catalyst precursor is placed in the central constant temperature zone of the quartz tube of the tube furnace, and a reducing gas is introduced. The tube furnace is gradually heated at a heating rate of 1-20 / min. When the temperature of the central constant temperature zone of the quartz tube reaches 100-500 °C, it is maintained for 0-5 h, and then cooled to room temperature; the cooled solid is placed in a Schlenk tube, 10-50 mL of water is added, and it is stirred for 1-12 h, and then filtered and dried to obtain the doped composite metal hydroxide supported Au-metal oxide catalyst. The pretreatment of the catalyst precursor in step 4) is to enable the displaced Au to interact more stably with the metal nanoparticles, and at the same time, the doped composite metal hydroxide is converted into a doped composite oxide. Since the subsequent catalytic reaction is carried out in an aqueous system, to prevent the doped composite oxide in the catalyst precursor from being restored to the doped composite metal hydroxide during the reaction, the restoration process is preferably carried out in water in step 4), and the doped composite oxide is restored to the doped composite metal hydroxide.

[0037] The present invention also provides a use of the aforementioned catalyst for catalyzing the preparation of amide compounds from alcohol molecules and amine molecules. Under the temperature of 20-150 °C, the pressure of 0.1-2.0 MPa and the atmosphere of air or oxygen, water, alcohol molecules, amine molecules and the aforementioned catalyst are added to the reactor, and the catalytic reaction is carried out for 0.5-72 h. The alcohol molecules include any at least one of aliphatic alcohols and aromatic alcohols; the amine molecules include any one of aromatic amines and aliphatic amines.

[0038] Further, the equation of the catalytic reaction is shown in formula (I):

[0039]

[0040] Wherein,

[0041] R 1 is selected from any one of C1-C6 alkyl, phenyl, and benzyl;

[0042] R 2 is selected from any one of -H, -CH 3 ;

[0043] R 3 is selected from any one of -CH 3 , -(CH 2 ) 3 CH 3 , -CH 2 CH 2 Ph, -CH 2 Ph.

[0044] Further, the selected reaction temperature is preferably 40-60 °C.

[0045] Further, the selected reactor is one of a Schlenk reactor and a stainless-steel reactor with a polytetrafluoroethylene liner.

[0046] Further, the added volume of water is 2 - 10 times the volume of ethanol.

[0047] Further, the mass ratio of the alcohol molecules to the amine molecules is 2 - 100:1.

[0048] Further, the molar ratio of Au in the catalyst to the amine molecules is 1:100 - 300.

[0049] Further, the reaction time is preferably 24 h - 72 h.

[0050] Further, after the reaction is completed, it is cooled, and the separation yield of the amide compound is determined by nuclear magnetic resonance.

[0051] In this catalytic use, the mechanism of the catalytic reaction (as shown in the appendix Figure 1 ) is specifically as follows:

[0052] (1) The variable-valence elements (at least one of Ce, Zr, Ga, Mn, Sn, La) doped on the surface of the catalyst are prone to generate oxygen defects during the preparation process, resulting in more oxygen vacancies. The oxygen vacancies can be used to enhance the adsorption of oxygen atoms. Therefore, the adsorption activation of the alcohol O - H bond can be strengthened.

[0053] (2) Similarly, Au and the adjacent oxygen vacancies can simultaneously adsorb oxygen, thereby synergistically activating oxygen. After the activation of oxygen is enhanced, more active *OOH species are further formed by reacting with the metal oxide-activated water.

[0054] (3) The active *OOH species activate the α - C - H bond of ethanol on the one hand and promote the dehydrogenation of the hemi - aldehyde amine to form amide compounds on the other hand. And hydrogen peroxide is produced as a by - product in this process.

[0055] (4) The basic sites on the surface of the doped composite metal hydroxide activate the amine N - H bond and catalyze the aldol condensation of aldehydes and amines.

[0056] The beneficial effects of the present invention are as follows:

[0057] 1. In the existing route for preparing amides, amide compounds are prepared by dehydrogenating alcohol molecules to form aldehydes, cross - condensing aldehydes with amines to form hemi - aldehyde amine intermediates, and then dehydrogenating the hemi - amide intermediates; among them, the externally added base mainly plays the role of alcohol dehydrogenation and amine activation. Without the externally added base, activation does not occur and the reaction cannot proceed further. However, the catalyst of the present invention can efficiently synthesize amide compounds by dehydrogenation, condensation, and re - dehydrogenation of alcohol molecules and amine molecules without the addition of an externally added base.

[0058] 2. In the catalyst of the present invention, due to the multiple interface synergistic catalysis of Au-metal oxide-doped composite metal hydroxide, in the reaction of preparing amide compounds from alcohol molecules and amine molecules, the surface oxygen vacancies of the doped composite metal hydroxide adsorb and activate the O-H bond of alcohol; Au cooperates with the oxygen vacancies to activate oxygen and forms active *OOH species with the metal oxide-activated water. On the one hand, the active *OOH species activates the α-C-H bond of ethanol, and on the other hand, promotes the dehydrogenation of semi-aldehyde amine to form amide compounds, and hydrogen peroxide is produced as a by-product in this process; the surface basic sites of the doped composite metal hydroxide activate the N-H bond of amine and catalyze the condensation of aldehyde amine.

[0059] 3. By using the catalyst of the present invention, in the reaction of preparing amide by alcohol oxidative amidation, the yield of amide can reach 23-98%. Among them, the electron-donating ability of Cu and Co to Au is not as strong as that of Ni. The Au-Ni oxide structure has a more electron-rich property, which will greatly enhance the activation of oxygen and further activate alcohol, thus affecting the activity of amide. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the mechanism of the catalytic reaction of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0062] Example 1

[0063] A doped hydrotalcite-supported Au catalyst Au@NiO x -Mg 2 Al 0.85 Ce 0.15 -LDHs, the loading amount of Au is 0.83 wt%, and the loading amount of NiO x is 5.0 wt%.

[0064] Step 1) Preparation of doped composite metal hydroxide

[0065] Accurately weigh 0.008 mol of Ni(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, 0.017 mol of Al(NO 3 ) 3 ·9H 2 O, 0.003 mol of Ce(NO 3 ) 3 ·6H 2Put O into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically treat until all the drugs are dissolved to form a clear and transparent solution (A);

[0066] Weigh 0.136 mol of NaOH into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically treat until all the drugs are dissolved to form a clear and transparent solution (B);

[0067] Weigh 0.01 mol of Na 2 CO 3 Into a 1 L four-necked flask, add 200 mL of deionized water for dissolution and record it as solution (C);

[0068] At room temperature, add a magnetic stir bar to the four-necked flask, stir at a rate of 300 rpm on a magnetic stirrer, and slowly drop solution A and solution B into the four-necked flask at the same time. Control the pH value at 10.0 ± 0.2 with a pH meter; after the dropping is completed, transfer the four-necked flask into a constant temperature water bath, control its temperature at 60 °C, and stir and age for 24 h at a rate of 500 rpm;

[0069] After the reaction, pour the supernatant into the waste liquid bucket, and obtain the sample from the lower layer of the turbid liquid by vacuum filtration. Wash it repeatedly with deionized water until the pH is neutral; then place the obtained sample in an oven at 60 °C for drying; use a mortar to grind the prepared NiMg 2 Al 0.85 Ce 0.15 -LDHs into powder and store it after drying;

[0070] Step 2) Reduction of the doped composite metal hydroxide

[0071] Accurately weigh 0.5 g of NiMg 2 Al 0.85 Ce 0.15 -LDHs hydrotalcite precursor into a porcelain boat, place the porcelain boat in the center of the quartz tube of the tube furnace, evacuate it with a vacuum pump after sealing and then slowly introduce the reducing gas H 2 to atmospheric pressure, and the gas flow rate is 40 ml / min; gradually heat it to 600 °C at a rate of 2 °C / min, hold for 2 h, and then cool down to obtain Ni-Mg 2 Al 0.85 Ce 0.15 -LDO;

[0072] Step 3) Displacement of Au

[0073] The reduced Ni-Mg 2 Al 0.85 Ce 0.15 -LDO is directly sealed with 5 ml of deoxygenated deionized water, poured into a glass tube, and magnetically stirred at 800 rpm and N 2Under protection, KAuCl was added dropwise at 25 °C 4 solution, and the reaction was carried out for 10 min. The ion equation of the displacement reaction is as follows:

[0074] 3Ni(s) + 2AuCl 4- (aq) = 2Au(s) + 3Ni 2+ (aq) + 8Cl - (aq)

[0075] After the reaction, it was washed repeatedly with deionized water. After each washing, it was centrifuged at 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the catalyst precursor Au@Ni-Mg 2 Al 0.85 Ce 0.15 -LDHs-G catalyst, where G represents displacement;

[0076] 4) Pretreatment and reduction

[0077] Au@Ni-Mg 2 Al 0.85 Ce 0.15 -LDHs-G was further pretreated in a tubular furnace with H 2 for once, the gas flow rate was 40 mL / min, it was gradually heated to 300 °C at 10 °C and then cooled, and then taken out to obtain Au@Ni-Mg 2 Al 0.85 Ce 0.15 -LDO-P, where P represents pretreatment;

[0078] Furthermore, Au@Ni-Mg 2 Al 0.85 Ce 0.15 -LDO-P was put into a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After completion, it was washed repeatedly with deionized water. After each washing, it was centrifuged at 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain sample one Au@NiO x -Mg 2 Al 0.85 Ce 0.15 -LDHs.

[0079] Test Example 1

[0080] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine, and 60 mg of the catalyst in Example 1 into a 20 mL Schlenk reactor, and then place it in a water bath at 70 °C for reaction for 24 h. After the reaction, quickly cool the reactor to room temperature. The product was detected and analyzed by liquid chromatography, and the yield of N-acetylphenethylamine was 97%.

[0081] Example 2

[0082] A doped hydrotalcite-supported Au catalyst Au@NiO x -Mg 2 Al 0.95 Ce 0.05 -LDHs, the loading amount of Au is 0.81 wt%, and the loading amount of NiO x is 5.0 wt%.

[0083] Step 1 Preparation of doped composite metal hydroxide

[0084] Accurately weigh 0.008 mol of Ni(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, 0.019 mol of Al(NO 3 ) 3 ·9H 2 O, 0.001 mol of Ce(NO 3 ) 3 ·6H 2 O and put them into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve the medicine until a clear and transparent solution (A) is formed;

[0085] Weigh 0.136 mol NaOH into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve the medicine until a clear and transparent solution (B) is formed;

[0086] Weigh 0.01 mol of Na 2 CO 3 into a 1 L four-necked flask, add 200 mL of deionized water to dissolve and label it as solution (C);

[0087] At room temperature, add a magnetic stir bar to the four-necked flask, stir at a rate of 300 rpm on a magnetic stirrer, and slowly drop solution A and solution B into the four-necked flask at the same time, and control the pH value at 10.0 ± 0.2 with a pH meter; after the dropping is completed, transfer the four-necked flask to a constant temperature water bath, control its temperature at 60 °C, and stir and age for 24 h at a rate of 500 rpm;

[0088] After the reaction, the supernatant was poured into the waste liquid bucket, and the lower layer of turbid liquid was obtained by vacuum filtration to obtain the sample, which was repeatedly washed with deionized water until the pH was neutral; then the obtained sample was placed in an oven at 60 °C for drying; the prepared NiMg 2 Al 0.95 Ce 0.05 -LDHs was ground into powder and stored after drying;

[0089] Step 2) Reduction of the support

[0090] Accurately weigh 0.5 g of NiMg 2 Al 0.95 Ce 0.05 -LDHs hydrotalcite precursor in a porcelain boat, place the porcelain boat in the center of the quartz tube of the tubular furnace, evacuate with a vacuum pump after sealing and then slowly introduce the reducing gas H 2 to atmospheric pressure, the gas flow rate is 40 ml / min, gradually heat up to 600 °C at 2 °C / min, hold for 2 h, cool down, and obtain Ni-Mg 2 Al 0.95 Ce 0.05 -LDO;

[0091] Step 3) Displacement of Au

[0092] The reduced Ni-Mg 2 Al 0.95 Ce 0.05 -LDO was directly sealed with 5 ml of deoxygenated deionized water, poured into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, KAuCl 4 solution was added dropwise at 25 °C, and the reaction was carried out for 10 min. The ionic equation of the displacement reaction is as follows:

[0093] 3Ni(s)+2AuCl 4- (aq)=2Au(s)+3Ni 2+ (aq)+8Cl - (aq)

[0094] After the reaction, it was repeatedly washed with deionized water, centrifuged for 5 min after each washing, the upper transparent liquid was poured into the waste liquid bucket, washed three times with water and then once with alcohol, and finally the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the Au@Ni-Mg 2 Al 0.95 Ce 0.05 -LDHs-G catalyst;

[0095] Step 4) Pre-treatment and restoration

[0096] Au@Ni-Mg 2 Al 0.95 Ce 0.05 -LDHs-G was further pretreated once in a tubular furnace with H 2 at a gas flow rate of 40 mL / min, gradually heated from 10 °C to 300 °C and then cooled, and then taken out to obtain Au@NiO x -MgAl-LDO-P;

[0097] Further, Au@NiO x -MgAl-LDO-P was placed in a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After completion, it was repeatedly washed with deionized water, centrifuged at 5 min each time after washing, the upper transparent liquid was poured into the waste liquid bucket, washed three times with water and then rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain Au@NiO x -Mg 2 Al 0.95 Ce 0.05 -LDHs catalyst.

[0098] Test Example 2

[0099] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine and 60 mg of the catalyst of Example 2 into a 20 mL Schlenk reactor, and then react it in a water bath at 70 °C for 24 h. After the reaction, the reactor was quickly cooled to room temperature. The product was detected and analyzed by liquid chromatography, and the yield of acetophenethylamine was 82%.

[0100] Example 3:

[0101] A doped hydrotalcite-supported Au catalyst Au@NiO x -Mg 2 Al 0.6 Ce 0.4 -LDHs, the loading amount of Au is 0.80 wt%, and the loading amount of NiO x is 5.0 wt%.

[0102] Step 1) Preparation of doped composite metal hydroxide

[0103] Accurately weigh 0.008 mol of Ni(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, 0.012 mol of Al(NO 3 ) 3 ·9H2 O, 0.008 mol Ce(NO 3 ) 3 ·6H 2 O was placed in a 250 mL small beaker, and 200 mL of deionized water was added. It was ultrasonicated until all the drugs were dissolved to form a clear and transparent solution (A);

[0104] 0.136 mol of NaOH was weighed in a 250 mL small beaker, and 200 mL of deionized water was added. It was ultrasonicated until all the drugs were dissolved to form a clear and transparent solution (B);

[0105] 0.01 mol of Na 2 CO 3 was added to a 1 L four-necked flask, and 200 mL of deionized water was added and dissolved, denoted as solution (C);

[0106] At room temperature, a magnetic stirrer bar was added to the four-necked flask, and it was stirred at a rate of 300 rpm on a magnetic stirrer. Solution A and solution B were simultaneously and slowly dropped into the four-necked flask, and the pH value was controlled at 10.0 ± 0.2 with a pH meter; after the dropping was completed, the four-necked flask was transferred to a constant temperature water bath, and its temperature was controlled at 60 °C, and it was stirred and aged for 24 h at a rate of 500 rpm;

[0107] After the reaction, the supernatant was poured into the waste liquid bucket, and the lower layer of turbid liquid was obtained by vacuum filtration. It was washed repeatedly with deionized water until the pH was neutral; then the obtained sample was placed in an oven at 60 °C for drying; the prepared NiMg 2 Al 0.6 Ce 0.4 -LDHs was ground into powder and stored after drying;

[0108] Step 2) Reduction of the support

[0109] Accurately weigh 0.5 g of NiMg 2 Al 0.6 Ce 0.4 -LDHs hydrotalcite precursor in a porcelain boat. The porcelain boat was placed in the center of the quartz tube of the tubular furnace. After sealing, it was evacuated with a vacuum pump and then slowly filled with the reducing gas H 2 to atmospheric pressure, and the gas flow rate was 40 ml / min. It was gradually heated to 600 °C at a rate of 2 °C / min, held for 2 h, and then cooled to obtain Ni-Mg 2 Al 0.6 Ce 0.4 -LDO;

[0110] Step 3) Displacement of Au

[0111] The reduced Ni-Mg 2 Al 0.6 Ce0.4 - The LDO was directly sealed with 5 mL of deoxygenated deionized water, poured into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, the KAuCl 4 solution was added dropwise at 25 °C, and the reaction was carried out for 10 min. The displacement reaction ionic equation is as follows:

[0112] 3Ni(s) + 2AuCl 4- (aq) = 2Au(s) + 3Ni 2+ (aq) + 8Cl - (aq)

[0113] After the reaction, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the Au@Ni-Mg 2 Al 0.6 Ce 0.4 -LDHs-G catalyst.

[0114] Step 4) Pretreatment and restoration

[0115] The Au@Ni-Mg 2 Al 0.6 Ce 0.4 -LDHs-G was further pretreated in a tubular furnace with H 2 once, the gas flow rate was 40 mL / min, it was gradually heated from 10 °C to 300 °C and then cooled, and then taken out. The Au@Ni-Mg 2 Al 0.6 Ce 0.4 -LDO-P;

[0116] Furthermore, the Au@Ni-Mg 2 Al 0.6 Ce 0.4 -LDO-P was put into a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After completion, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the Au@NiO x -MgAl-LDHs catalyst of Example 3.

[0117] Test Example 3

[0118] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine, and 60 mg of the catalyst of Example 3 into a 20 mL Schlenk reactor, and then place it in a water bath at 70 °C and react for 24 h. After the reaction, quickly cool the reactor to room temperature. The product was detected and analyzed by liquid chromatography, and the yield of acetophenethylamine was 93%.

[0119] Example 4:

[0120] A doped hydrotalcite-supported Au catalyst Au@CoO x -Mg 2 Al 0.85 Ce 0.15 -LDHs, the loading amount of Au is 0.78 wt%, and the loading amount of CoO x is 9.3 wt%.

[0121] Step 1) Preparation of doped composite metal hydroxide

[0122] Accurately weigh 0.02 mol of Co(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, 0.017 mol of Al(NO 3 ) 3 ·9H 2 O, 0.003 mol of Ce(NO 3 ) 3 ·6H 2 O and put them into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve the medicine until a clear and transparent solution (A) is formed;

[0123] Weigh 0.16 mol of NaOH into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve the medicine until a clear and transparent solution (B) is formed;

[0124] Weigh 0.01 mol of Na 2 CO 3 into a 1 L four-necked flask, add 200 mL of deionized water and dissolve it, denoted as solution (C);

[0125] At room temperature, add a magnetic stir bar to the four-necked flask, stir it at a rate of 300 rpm on a magnetic stirrer, and slowly drop solution A and solution B into the four-necked flask at the same time, and control the pH value at 10.0 ± 0.2 with a pH meter; after the dropping is completed, transfer the four-necked flask to a constant temperature water bath, control its temperature at 60 °C, and stir and age it at a rate of 500 rpm for 24 h;

[0126] After the reaction, pour the supernatant into the waste liquid bucket, and obtain the sample from the lower layer of turbid liquid by vacuum filtration under reduced pressure. Wash it repeatedly with deionized water until the pH is neutral. Then place the obtained sample in an oven at 60 °C for drying. Use a mortar to grind the prepared CoMg 2 Al 0.85 Ce 0.15 -LDHs into powder and store it after drying;

[0127] Step 2) Reduction of the support

[0128] Accurately weigh 0.5 g of CoMg 2 Al 0.85 Ce 0.15 -LDHs hydrotalcite precursor in a porcelain boat, place the porcelain boat in the center of the quartz tube of the tubular furnace, evacuate it with a vacuum pump after sealing and then slowly introduce the reducing gas H 2 to atmospheric pressure, and the gas flow rate is 40 ml / min. Gradually heat it to 600 °C at 2 °C / min, hold for 2 h, and then cool down to obtain Co-Mg 2 Al 0.85 Ce 0.15 -LDO;

[0129] Step 3) Displacement of Au

[0130] Seal the reduced Co-Mg 2 Al 0.85 Ce 0.15 -LDO directly with 5 ml of deoxygenated deionized water, pour it into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, add KAuCl 4 solution dropwise at 25 °C and react for 10 min. The ionic equation of the displacement reaction is as follows:

[0131] 3Co(s)+2AuCl 4- (aq)=2Au(s)+3Co 2+ (aq)+8Cl - (aq)

[0132] After the reaction, wash it repeatedly with deionized water, centrifuge for 5 min after each wash, pour the upper transparent liquid into the waste liquid bucket, wash it three times with water and then once with alcohol. Finally, dry the solid remaining after centrifugation in a vacuum drying oven at 60 °C for 24 h to obtain the Au@Co-Mg 2 Al 0.85 Ce 0.15 -LDHs-G catalyst;

[0133] Step 4) Pre-treatment and restoration

[0134] Au@Co-Mg 2 Al 0.85 Ce 0.15 -LDHs-G was further pretreated once in a tube furnace with H 2 The gas flow rate was 40 mL / min, and it was gradually heated to 300 °C at 10 °C and then cooled. Then it was taken out, and Au@Co-Mg 2 Al 0.85 Ce 0.15 -LDHs-G;

[0135] Furthermore, Au@Co-Mg 2 Al 0.85 Ce 0.15 -LDO-P was placed in a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After that, it was repeatedly washed with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge. The upper clear liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the Au@CoO x -Mg 2 Al 0.85 Ce 0.15 -LDHs catalyst.

[0136] Test Example 4

[0137] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine and 60 mg of the catalyst of Example 4 into a 20 mL Schlenk reactor, and then place it in a water bath at 70 °C for reaction for 24 h. After the reaction, the reactor was quickly cooled to room temperature. The product was detected and analyzed by liquid chromatography, and the yield of acetophenethylamine was 58%.

[0138] Example 5:

[0139] A doped hydrotalcite-supported Au catalyst Au@CuO x -Mg 2 Al 0.85 Ce 0.15 -LDHs, the loading amount of Au is 0.84 wt%, and the loading amount of CuO x is 3.0 wt%.

[0140] Step 1) Preparation of doped composite metal hydroxide

[0141] Accurately weigh 0.004 mol of Cu(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H2 O, 0.017 mol of Al(NO 3 ) 3 ·9H 2 O, 0.003 mol of Ce(NO 3 ) 3 ·6H 2 O were placed in a 250 mL beaker, and 200 mL of deionized water was added. After ultrasonic treatment until all the drugs were dissolved to form a clear and transparent solution (A);

[0142] 0.128 mol of NaOH was weighed in a 250 mL beaker, and 200 mL of deionized water was added. After ultrasonic treatment until all the drugs were dissolved to form a clear and transparent solution (B);

[0143] 0.01 mol of Na 2 CO 3 was placed in a 1 L four-necked flask, and 200 mL of deionized water was added and dissolved, denoted as solution (C);

[0144] At room temperature, a magnetic stirrer bar was added to the four-necked flask, and it was stirred at a rate of 300 rpm on a magnetic stirrer. Solution A and solution B were simultaneously and slowly dropped into the four-necked flask, and the pH value was controlled at 10.0 ± 0.2 with a pH meter; after the dropping was completed, the four-necked flask was transferred to a constant temperature water bath, and its temperature was controlled at 60 °C, and it was stirred and aged for 24 h at a rate of 500 rpm;

[0145] After the reaction, the supernatant was poured into the waste liquid bucket, and the lower layer of turbid liquid was obtained as a sample by vacuum filtration. It was repeatedly washed with deionized water until the pH was neutral; then the obtained sample was placed in an oven at 60 °C for drying; the prepared CuMg 2 Al 0.85 Ce 0.15 -LDHs was ground into powder and stored after drying;

[0146] Step 2) Reduction of the support

[0147] Accurately weigh 0.5 g of CuMg 2 Al 0.85 Ce 0.15 -LDHs hydrotalcite precursor in a porcelain boat. The porcelain boat was placed in the center of the quartz tube of a tube furnace. After sealing, it was evacuated with a vacuum pump and then slowly filled with a reducing gas H 2 to atmospheric pressure, and the gas flow rate was 40 ml / min. It was gradually heated to 600 °C at a rate of 2 °C / min, held for 2 h, and then cooled to obtain Cu-Mg 2 Al 0.85 Ce 0.15 -LDO;

[0148] Step 3) Displacement of Au

[0149] The reduced Cu-Mg 2 Al 0.85 Ce 0.15 -LDO was directly liquid-sealed with 5 ml of deoxygenated deionized water, poured into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, the KAuCl 4 solution was added dropwise at 25 °C, and the reaction was carried out for 10 min. The displacement reaction ionic equation is as follows:

[0150] 3Cu(s) + 2AuCl 4- (aq) = 2Au(s) + 3Cu 2+ (aq) + 8Cl - (aq)

[0151] After the reaction, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge, and the upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain Au@Cu-Mg 2 Al 0.85 Ce 0.15 -LDHs-G catalyst;

[0152] Step 4) Pretreatment and restoration

[0153] The Au@Cu-Mg 2 Al 0.85 Ce 0.15 -LDHs-G was further pretreated in a tube furnace with H 2 once. The gas flow rate was 40 mL / min, and it was gradually heated to 300 °C at 10 °C and then cooled, and then taken out to obtain Au@Cu-Mg 2 Al 0.85 Ce 0.15 -LDO-P;

[0154] Furthermore, the Au@Cu-Mg 2 Al 0.85 Ce 0.15 -LDO-P was placed in a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After completion, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge, and the upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the Au@CuO x -Mg 2 Al 0.85 Ce 0.15 -LDHs catalyst of Example 5.

[0155] Test Example 5

[0156] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine, and 60 mg of the catalyst of Example 5 into a 20 mL Schlenk reactor, and then place it in a water bath at 70 °C and react for 24 h. After the reaction, quickly cool the reactor to room temperature. The product is detected and analyzed by liquid chromatography, and the yield of acetophenethylamine is 29%.

[0157] Example 6:

[0158] A doped hydrotalcite-supported Au catalyst Au@NiO x -Mg 2 Al 0.85 In 0.15 -LDHs, the loading amount of Au is 0.80 wt%, and the loading amount of NiO x is 5.0 wt%.

[0159] Step 1) Preparation of doped composite metal hydroxide

[0160] Accurately weigh 0.008 mol of Ni(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, 0.017 mol of Al(NO 3 ) 3 ·9H 2 O, 0.003 mol of In(NO 3 ) 3 ·5H 2 O and put them into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve until all the drugs are dissolved to form a clear and transparent solution (A);

[0161] Weigh 0.136 mol of NaOH into a 250 mL small beaker, add 200 mL of deionized water, and ultrasonically dissolve until all the drugs are dissolved to form a clear and transparent solution (B);

[0162] Weigh 0.01 mol of Na 2 CO 3 into a 1 L four-necked flask, add 200 mL of deionized water to dissolve and record it as solution (C);

[0163] Add a magnetic stir bar to a four-necked flask at room temperature and stir at 300 rpm on a magnetic stirrer. Slowly drip solution A and solution B into the four-necked flask simultaneously, and control the pH value at 10.0 ± 0.2 with a pH meter. After the dripping is completed, transfer the four-necked flask to a constant temperature water bath and control the temperature at 60 °C. Stir and age for 24 h at a rate of 500 rpm.

[0164] After the reaction, pour the supernatant into the waste liquid bucket, and obtain the sample by vacuum filtration of the lower layer turbid liquid. Wash it repeatedly with deionized water until the pH is neutral. Then place the obtained sample in an oven at 60 °C for drying. Grind the prepared NiMg 2 Al 0.85 In 0.15 -LDHs into powder and store it after drying.

[0165] Step 2) Reduction of the support

[0166] Accurately weigh 0.5 g of NiMg 2 Al 0.85 In 0.15 -LDHs hydrotalcite precursor in a porcelain boat, place the porcelain boat in the center of the quartz tube of a tube furnace, evacuate it with a vacuum pump after sealing, and then slowly introduce the reducing gas H 2 to atmospheric pressure, and the gas flow rate is 40 ml / min. Gradually heat it to 600 °C at a rate of 2 °C / min, hold for 2 h, and then cool down to obtain Ni-Mg 2 Al 0.85 In 0.15 -LDO;

[0167] Step 3) Displacement of Au

[0168] Directly liquid seal the reduced Ni-Mg 2 Al 0.85 In 0.15 -LDO with 5 ml of deoxygenated deionized water, pour it into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, add KAuCl 4 solution dropwise at 25 °C and react for 10 min. The ionic equation of the displacement reaction is as follows:

[0169] 3Ni(s)+2AuCl 4- (aq)=2Au(s)+3Ni 2+ (aq)+8Cl - (aq)

[0170] After the reaction, wash with deionized water repeatedly. After each washing, centrifuge for 5 min, pour the upper transparent liquid into the waste liquid bucket. After washing three times with water, rinse once with alcohol. Finally, dry the remaining solid after centrifugation in a vacuum drying oven at 60 °C for 24 h to obtain Au@Ni-Mg 2 Al 0.85 In 0.15 -LDHs-G catalyst;

[0171] Step 4) Pretreatment and restoration

[0172] Take Au@Ni-Mg 2 Al 0.85 In 0.15 -LDHs-G and further use H in a tube furnace 2 Pretreat once, with a gas flow rate of 40 mL / min, gradually heat up to 300 °C at 10 °C and then cool down, and then take out to obtain Au@Ni-Mg 2 Al 0.85 In 0.15 -LDO-P;

[0173] Further take Au@Ni-Mg 2 Al 0.85 In 0.15 -LDO-P and put it into a 50 mL flask, add 25 mL of deionized water, stir at 500 rpm for 6 h. After completion, wash with deionized water repeatedly. After each washing, centrifuge for 5 min, pour the upper transparent liquid into the waste liquid bucket. After washing three times with water, rinse once with alcohol. Finally, dry the remaining solid after centrifugation in a vacuum drying oven at 60 °C for 24 h to obtain Au@NiO of Example 6 x -Mg 2 Al 0.85 In 0.15 -LDHs catalyst.

[0174] Test Example 6

[0175] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenethylamine and 60 mg of the catalyst of Example 6 into a 20 mL Schlenk reactor, and then place it in a water bath at 70 °C for reaction for 24 h. After the reaction, quickly cool the reactor to room temperature. The product is detected and analyzed by liquid chromatography, and the yield of N-acetylphenethylamine is 64%.

[0176] Comparative example:

[0177] An undoped hydrotalcite-supported Au catalyst Au@NiO x -MgAl-LDHs, the loading amount of Au is 0.80 wt%, and NiO x The loading amount of is 5.0 wt%.

[0178] Step 1) Preparation of composite metal hydroxide

[0179] Accurately weigh 0.008 mol of Ni(NO 3 ) 2 ·6H 2 O, 0.04 mol of Mg(NO 3 ) 2 ·6H 2 O, and 0.02 mol of Al(NO 3 ) 3 ·9H 2 O and place them in a 250 mL beaker. Add 200 mL of deionized water and ultrasonicate until all the drugs are dissolved to form a clear and transparent solution (A);

[0180] Weigh 0.136 mol of NaOH in a 250 mL beaker, add 200 mL of deionized water, and ultrasonicate until all the drugs are dissolved to form a clear and transparent solution (B);

[0181] Weigh 0.01 mol of Na 2 CO 3 into a 1 L four-necked flask, add 200 mL of deionized water to dissolve it and label it as solution (C);

[0182] Add a magnetic stir bar to the four-necked flask at room temperature and stir it at a rate of 300 rpm on a magnetic stirrer. Slowly drip solution A and solution B into the four-necked flask at the same time, and control the pH value at 10.0 ± 0.2 with a pH meter; after the dripping is completed, transfer the four-necked flask to a constant temperature water bath, control its temperature at 60 °C, and stir and age it at a rate of 500 rpm for 24 h.

[0183] After the reaction, pour the supernatant into the waste liquid bucket, and obtain the sample by vacuum filtration of the lower layer turbid liquid. Wash it repeatedly with deionized water until the pH is neutral; then place the obtained sample in an oven at 60 °C for drying; grind the prepared NiMgAl-LDHs into powder with a mortar and store it in a dry place;

[0184] Step 2) Reduction of composite metal hydroxide

[0185] Accurately weigh 0.5 g of the NiMgAl-LDHs hydrotalcite precursor in a porcelain boat, place the porcelain boat in the center of the quartz tube of the tube furnace, evacuate it with a vacuum pump after sealing and then slowly introduce the reducing gas H 2 to atmospheric pressure, and the gas flow rate is 40 ml / min; gradually heat it to 600 °C at a rate of 2 °C / min, hold for 2 h, and then cool down to obtain Ni-MgAl-LDO;

[0186] Step 3) Displacement of Au

[0187] The reduced Ni-MgAl-LDO was directly sealed with 5 mL of deoxygenated deionized water, poured into a glass tube, and under magnetic stirring at 800 rpm and N 2 protection, KAuCl 4 solution was added dropwise at 25 °C, and the reaction was carried out for 10 min. The ion equation of the displacement reaction is as follows:

[0188] 3Ni(s) + 2AuCl 4- (aq) = 2Au(s) + 3Ni 2+ (aq) + 8Cl - (aq)

[0189] After the reaction, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the catalyst precursor Au@Ni-MgAl-LDHs-G, where G represents displacement.

[0190] 4) Pretreatment and reduction

[0191] Au@Ni-MgAl-LDHs-G was further pretreated in a tube furnace with H 2 once. The gas flow rate was 40 mL / min. It was gradually heated to 300 °C at 10 °C and then cooled, and then taken out to obtain Au@Ni-MgAl-LDO-P, where P represents pretreatment;

[0192] Further, Au@Ni-MgAl-LDO-P was put into a 50 mL flask, 25 mL of deionized water was added, and it was stirred at 500 rpm for 6 h. After the end, it was washed repeatedly with deionized water. After each washing, it was centrifuged for 5 min with a centrifuge. The upper transparent liquid was poured into the waste liquid bucket. After washing three times with water, it was rinsed once with alcohol. Finally, the solid remaining after centrifugation was dried in a vacuum drying oven at 60 °C for 24 h to obtain the comparative sample Au@NiO x -MgAl-LDHs.

[0193] Comparative test example

[0194] Accurately measure 4.0 mL of water, 2.0 mL of ethanol, 0.5 mmol of phenylethylamine, and 60 mg of catalyst sample 1 into a 20 mL Schlenk reactor, and then place it in a water bath at 60 °C for reaction for 24 h. After the reaction, the reactor was quickly cooled to room temperature, and the product was detected and analyzed by liquid chromatography. The yield of N-acetylphenethylamine was 62.8%.

[0195] The above are only the preferred embodiments of the present invention, and are not any other form of limitation to the present invention. Any modification or equivalent change made according to the technical essence of the present invention still belongs to the scope protected by the present invention.

Claims

1. A doped hydrotalcite-supported Au catalyst, characterized in that, the catalyst is a doped composite metal hydroxide-supported Au-metal oxide, wherein the composite metal hydroxide comprises magnesium hydroxide, boehmite, and at least one of nickel hydroxide, cobalt hydroxide, and copper hydroxide; the doped element is at least one of Ce, Zr, Ga, Mn, Sn, and La; the metal oxide comprises at least one of nickel oxide, copper oxide, and cobalt oxide, wherein the loading amount of Au is 0.01-3 wt%; and the loading amount of the doped element is 0-10 wt%, and the loading amount does not include 0; and the loading amount of the metal oxide is 3-10 wt%; wherein the doped composite metal hydroxide is formed by subjecting divalent metal nitrates, trivalent metal nitrates, and doped metal nitrates to a precipitation reaction, and the doped composite metal hydroxide comprises divalent metal hydroxides, trivalent metal hydroxides, and doped metal hydroxides; the divalent metal comprises Mg and at least one of Ni, Co, and Cu; the trivalent metal is Al; the doped metal comprises at least one of Ce, Zr, Ga, Mn, Sn, and La; the molar ratio of divalent metal to trivalent metal is (2-4):1; the molar ratio of divalent metal to doped metal is (2-40):1; The catalyst shows characteristic diffraction peaks of hydrotalcite at 11.80 o , 23.58 o , 34.42 o , 38.98 o , 46.58 o , 60.52 o , 61.93 o for (003), (006), (012), (015), (018), (110), and (113), and obvious characteristic diffraction peaks of the doped metal oxide also appear.

2. A method for preparing the catalyst according to claim 1, characterized in that, the preparation method comprises the following steps: Step 1) Preparation of the doped composite metal hydroxide The doped composite metal hydroxide is formed by subjecting divalent metal nitrates, trivalent metal nitrates, and doped metal nitrates to a precipitation reaction, and the doped composite metal hydroxide comprises divalent metal hydroxides, trivalent metal hydroxides, and doped metal hydroxides; in Step 1), the molar ratio of divalent metal to trivalent metal is (2-4):1; the molar ratio of divalent metal to doped metal is (2-40):1; Step 2) Reduction of the doped composite metal hydroxide The doped composite metal hydroxide is taken and reduced to obtain a doped composite oxide-supported metal nanoparticle; Step 3) Au replacement The doped composite oxide-supported metal nanoparticle is taken, and Au is introduced for replacement to obtain a catalyst precursor, i.e., a doped composite metal hydroxide-supported Au-metal nanoparticle; Step 4) Pretreatment and restoration The catalyst precursor is taken and subjected to reduction pretreatment and restoration to obtain a doped composite metal hydroxide-supported Au-metal oxide catalyst.

3. According to the method for preparing the catalyst of claim 2, characterized in that, in Step 2), the doped composite metal hydroxide is weighed and placed in a tubular furnace, and under a hydrogen atmosphere, the temperature is raised to 300-800 °C and maintained for 0-5 h, wherein the time does not include 0, to obtain the doped composite oxide-supported metal nanoparticle.

4. According to the method for preparing the catalyst of claim 2, characterized in that, In step 3), the doped composite oxide loaded with metal nanoparticles is sealed with deoxygenated deionized water and poured into a container. While stirring at 400 - 1000 revolutions per minute, an aqueous Au solution is dropped into the container, and it is vigorously stirred at room temperature for 5 - 120 min.

5. The method for preparing the catalyst according to claim 2, characterized in that, in step 4), the catalyst precursor is placed in the central constant temperature zone of the quartz tube of a tube furnace, a reducing gas is introduced, and the tube furnace is gradually heated at a heating rate of 1 - 20 °C / min. When the temperature of the central constant temperature zone of the quartz tube reaches 100 - 500 °C, it is maintained for 0 - 5 h (excluding 0), and then cooled to room temperature; the cooled solid is placed in a Schlenk tube, 10 - 50 mL of water is added, stirred for 1 - 12 h, and filtered and dried to obtain the doped composite metal hydroxide supported Au-metal oxide catalyst.

6. Use of the catalyst according to claim 1 for catalyzing the preparation of amide compounds from alcohol molecules and amine molecules, characterized in that, at a temperature of 20 - 150 °C, a pressure of 0.1 - 2.0 MPa, and in the presence of air or oxygen, water, alcohol molecules, amine molecules and the catalyst are added to a reactor for a catalytic reaction for 0.5 - 72 h. The alcohol molecules include any at least one of aliphatic alcohols and aromatic alcohols; the amine molecules include any one of aromatic amines and aliphatic amines.

7. The use according to claim 6, characterized in that, the equation of the catalytic reaction is as shown in formula (I): Formula (I) wherein, R 1 selected from any one of C1-C6 alkyl, phenyl, and benzyl; R 2 Selected from -H, -CH 3 any one of; R 3 Selected from -CH 3 、-(CH 2 ) 3 CH 3 、-CH 2 CH 2 Ph, -CH 2 Ph, any one of them.

8. The use of the catalyst according to claim 6, characterized in that, the molar ratio of Au in the catalyst to the amine molecules is 1:100 - 300.

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