Pt-mo with uniform interface structure X Process for the preparation of a catalyst and use

Abstract

The application provides a Pt-MO catalyst with uniform interface structure X The application relates to a preparation method and application of a catalyst, and the preparation method comprises the following steps: pretreating a carrier by using concentrated nitric acid; mixing an auxiliary compound, a complexing agent, a solvent, and the pretreated carrier to obtain a mixture; and aging, drying, and calcining the mixture to obtain a composite material loaded with an auxiliary oxide MO X The auxiliary oxide MO X Is Bi2O3 or Sb2O3; and the composite material is deposited with Pt by using an atomic layer deposition method to obtain a Pt-MO X Catalyst with Bi2O3 or Sb2O3 as the auxiliary oxide. The catalyst has high interface content of Pt-auxiliary oxide, uniform interface structure distribution, high Pt particle dispersity, uniform particle size, and can efficiently catalyze glycerol oxidation to prepare 1,3-dihydroxyacetone (DHA) in a heterogeneous medium, and has high glycerol conversion rate and DHA yield, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of organic chemical catalyst preparation, specifically, it relates to a Pt-MO with a uniform metal-oxide interface structure. X Preparation methods and applications of catalysts. Background Technology

[0002] Glycerol is widely available, especially as a byproduct in the transesterification process of biodiesel production. It possesses abundant functional groups, allowing for the development of a range of downstream byproducts. Among these, the secondary hydroxyl oxidation product, 1,3-dihydroxyacetone (DHA), is one of the most economically valuable, with a value approximately 250 times that of glycerol.

[0003] The process for producing DHA from glycerol is simple, the production conditions are mild, and the oxidant used in the process is environmentally friendly. It not only meets the "two-carbon" requirement (carbon emission reduction) but also holds promise for replacing the low-productivity microbial transformation process used in traditional DHA production. Therefore, the selective catalytic oxidation of glycerol to DHA is a highly attractive research topic in both academia and industrial production.

[0004] Currently, supported noble metal catalysts such as Au-based, Pd-based, and Pt-based catalysts exhibit excellent performance in the selective catalytic oxidation of glycerol to DHA. Previous studies have shown that alkaline conditions promote the isomerization reaction and further oxidation of the target product DHA and the reaction byproduct glyceraldehyde (GLYD), easily leading to a decrease in DHA selectivity, even to zero. Therefore, DHA is more easily generated and exhibits higher selectivity under non-alkaline conditions. Numerous studies have shown that adding p-electron-containing promoters, such as Bi and Sb, to noble metal catalysts under non-alkaline conditions is beneficial for improving the selectivity of the reaction product DHA; however, byproducts such as glyceric acid are easily adsorbed onto the catalyst, inhibiting catalytic activity. Therefore, developing novel catalysts for the selective catalytic oxidation of glycerol to dihydroxyacetone to improve glycerol conversion and DHA selectivity is of great significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a Pt-MO X Pt-MO with high interface content, uniform interface structure, and uniform and highly dispersed Pt nanoparticles X The catalyst preparation method has the characteristics of high catalytic activity, high glycerol conversion rate, and high selectivity for the target product DHA in the selective catalytic oxidation of glycerol to dihydroxyacetone.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A Pt-MO with uniform interface structureX A method for preparing a catalyst, the method comprising the following steps:

[0008] (1) Carrier pretreatment: The carrier was pretreated with concentrated nitric acid;

[0009] (2) Loaded additive oxide: The additive compound, complexing agent, solvent, and pretreated carrier are mixed to obtain a mixture; the mixture is aged and then dried; and then calcined in a muffle furnace to obtain the loaded additive oxide MO. X Composite material; the auxiliary agent oxide MO X It is either bismuth oxide (Bi₂O₃) or antimony oxide (Sb₂O₃);

[0010] (3) Platinum-loaded Pt: Pt was deposited on the calcined composite material using atomic layer deposition to obtain Pt-MO with Bi2O3 or Sb2O3 as auxiliary oxides. X Catalyst, namely Pt-Bi2O3 or Pt-Sb2O3 catalyst.

[0011] The present invention is further configured such that, in step (1), the carrier is a commercially available carbon carrier; the carrier is selected from activated carbon, carbon black, carbon nanofibers, and carbon nanotubes with closed ends; preferably, the carrier is a carbon nanotube with closed ends.

[0012] The present invention is further configured such that, in step (1), the carrier and concentrated nitric acid are mixed and condensed and circulated at a temperature of 80–120°C. After the circulation is completed, the mixture is filtered, washed, and repeated 2–5 times. The carrier pretreated with concentrated nitric acid is dried at a temperature of 80–110°C for 10–18 hours. The time for each condensation cycle is 0.5–3 hours, and the ratio of carrier to nitric acid in each condensation cycle is (2–10) g: 100 mL.

[0013] The present invention is further configured such that, in step (2), the auxiliary compound is a compound of metal Bi or Sb, the complex is citric acid and polyethylene glycol, and the solvent is nitric acid solution.

[0014] Furthermore, the compound of metallic Bi is selected from bismuth acetate, bismuth nitrate pentahydrate, and bismuth chloride; preferably bismuth nitrate pentahydrate; the compound of metallic Sb is selected from antimony powder and antimony trichloride; preferably antimony trichloride.

[0015] The present invention is further configured such that, in step (2), the auxiliary compound, complexing agent, and solvent are mixed and stirred for 2-5 hours to obtain an auxiliary precursor solution; the auxiliary precursor solution is dropwise added to the carrier and stirred evenly, aged at room temperature for 10-18 hours, and then dried at 80-110°C for 10-18 hours, and then ground; subsequently calcined in a muffle furnace at a heating rate of 1-5°C / min, and calcined at a constant temperature of 200-400°C for 5-20 minutes to obtain the supported auxiliary oxide MO. X Composite materials.

[0016] Furthermore, the heating rate is 1.5 to 5 °C / min, more preferably 5 °C / min.

[0017] Furthermore, the calcination temperature is 200–300°C, more preferably 250°C.

[0018] Furthermore, the constant temperature calcination time is 8 to 17 minutes, more preferably 10 minutes.

[0019] The present invention is further configured such that, in step (3), the supported auxiliary agent oxide MO is... X The composite material was dissolved in anhydrous ethanol at a ratio of (5–15) mg: 1 ml, and after ultrasonic treatment for 15–60 min, it was uniformly coated onto a glass slide. Subsequently, using a room-temperature liquid source Pt precursor MeCpPtMe3 as the Pt raw material for deposition, Pt precursor and O3 were alternately introduced sequentially at an atomic layer deposition reaction temperature of 200–400 °C. The pulse, holding, and evacuation times of the Pt precursor were 0.1–1 s, 3–15 s, and 25–60 s, respectively; the pulse, holding, and evacuation times of the O3 were 0.5–2 s, 3–15 s, and 25–60 s, respectively. The deposition cycle was 1–25 times to prepare supported Pt-MO. X catalyst.

[0020] Furthermore, the mixing ratio of the carrier to ethanol is (8-12) mg:1 ml, more preferably 12 mg:1 ml.

[0021] Furthermore, the ultrasonic treatment time is 30 to 50 minutes, more preferably 40 minutes.

[0022] Furthermore, the atomic layer deposition reaction temperature is 250–350°C, more preferably 270°C.

[0023] Furthermore, the pulse duration of the Pt precursor is 0.3–0.8 s, more preferably 0.5 s.

[0024] Furthermore, the pulse duration of the O3 is 0.8 to 1.5 seconds, more preferably 1 second.

[0025] Furthermore, the holding time for the Pt precursor and O3 is 8 to 12 seconds, more preferably 12 seconds.

[0026] Furthermore, the pumping time for the Pt precursor and O3 is 25-50 seconds, more preferably 25 seconds.

[0027] Furthermore, the deposition cycle is performed 3 to 20 times, preferably 3 to 15 times or 5 to 15 times, and more preferably 5 to 10 times.

[0028] A second aspect of the invention is that it provides the Pt-MO X Application of catalysts in the selective catalytic oxidation of glycerol to prepare DHA.

[0029] The present invention is further configured such that the Pt-MO X The selective catalytic oxidation of glycerol can be carried out under batch conditions. The conditions for the batch reaction are: glycerol aqueous solution and the Pt-MO... X The catalyst is placed in the reactor, and the reaction temperature is 40-80℃, preferably 60℃; the O2 flow rate is 100-300 ml / min, preferably 120-200 ml / min, and more preferably 150 ml / min.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The supported Pt-MO prepared in this invention X The catalyst's structure, from top to bottom, is Pt-promoter oxide-support. The catalyst exhibits a high content of Pt-promoter oxide at the interface, a uniformly distributed interface structure, and Pt particles with high dispersibility and uniform particle size. Compared to single-metal Pt catalysts, the presence of the Pt-promoter oxide interface allows the main product of glycerol oxidation to change from glyceric acid and glyceraldehyde to 1,3-dihydroxyacetone (DHA). X The catalyst facilitates the efficient catalytic oxidation of glycerol to 1,3-dihydroxyacetone (DHA) in heterogeneous media, with a glycerol conversion rate of up to 97% and a DHA yield of up to 64%.

[0032] The catalyst is simple and easy to prepare, and has good stability, is recyclable and reusable. The reaction process of using the catalyst to oxidize glycerol to prepare 1,3-dihydroxyacetone is mild and environmentally friendly, and has broad application prospects. Attached Figure Description

[0033] Figure 1HAADF-STEM of Pt-Bi2O3 / CNTs prepared in Example 1;

[0034] Figure 2 HAADF-STEM of Pt-Bi2O3 / CNTs prepared in Example 4;

[0035] Figure 3 HAADF-STEM of Pt-Bi2O3 / CNTs prepared in Example 5;

[0036] Figure 4 HAADF-STEM of Pt-Bi2O3 / CNTs prepared in Comparative Example 1;

[0037] Figure 5 The image shows the XRD pattern of the Pt1Bi1 intermetallic compound catalyst prepared in Comparative Example 3. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art.

[0039] The formulas for calculating the glycerol conversion, product selectivity, and yield in the selective oxidation of glycerol to 1,3-dihydroxyacetone are as follows:

[0040] X(%)=(n 初始甘油 -n 反应后甘油 ) / n 初始甘油 ×100%

[0041] S i (%) = (n) 组分i ×A i ) / (n 初始甘油 ×3)×100%

[0042] Y i (%) = X × S i ×100%

[0043] Where X represents the conversion rate of glycerol, in percentage (%).

[0044] n 初始甘油 n 反应后甘油 These represent the initial and post-reaction amounts of glycerol, respectively, in mol.

[0045] Si The selectivity of component i is expressed in %.

[0046] n 组分i This indicates the amount of substance of component i after the reaction, expressed in mol.

[0047] A i This indicates the number of carbon atoms in the molecule of component i;

[0048] Y i This represents the yield of component i, expressed as a percentage.

[0049] The study found that the Pt nanoparticles supported on the catalyst surface exist as truncated octahedrons. By establishing a model and solving the problem, the number of atoms at each position in the Pt nanoparticles can be obtained. The calculation method is shown in Table 1.

[0050] By measuring the particle size of Pt particles on the catalyst surface, the number of Pt atoms N in each particle can be calculated. T By determining the intermediate parameter m, the number of atoms at different positions of the Pt particle can be calculated, including the number of interfacial atoms N of the Pt-auxiliary oxide in each Pt particle. interface Based on the number of interface atoms N in each Pt particle. interface With the total number of atoms N T The ratio can reflect the relative content of Pt-auxiliary oxide interface in Pt particles.

[0051] Table 1. Formulas for calculating the number of atoms and Pt particles at different positions in each Pt particle.

[0052]

[0053] Example 1

[0054] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it clean with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of carbon nanotubes treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise to the carbon nanotubes while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 12h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0055] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 10 times. The catalyst prepared above was characterized by TEM and surface scanning, as shown in the figure. Figure 1 As shown, a supported Pt-Bi2O3 catalyst was successfully prepared, with good Pt particle dispersion and uniform particle size, averaging 2.26 ± 0.38 nm. According to the calculation method in Table 1, the number of interface atoms N in each Pt particle... interface With the total number of atoms N T The proportion was 5.15%.

[0056] 0.0217 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate was 70%, and DHA selectivity was 58%.

[0057] Example 2

[0058] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 300℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0059] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 10 times. The catalyst prepared above was characterized by TEM and scanned. Figure 1 Similarly, it can be seen that a supported Pt-Bi2O3 catalyst was prepared, and the Pt particles have good dispersion and uniform particle size.

[0060] 0.030 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C for 6 h under normal pressure. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate was 67%, and DHA selectivity was 62%.

[0061] Example 3

[0062] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise to the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 200℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0063] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 10 times. The catalyst prepared above was characterized by TEM and scanned. Figure 1 Similarly, it can be seen that a supported Pt-Bi2O3 catalyst was prepared, and the Pt particles have good dispersion and uniform particle size.

[0064] 0.030 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate 61%, and DHA selectivity 51%.

[0065] Example 4

[0066] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0067] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was 15 times. The catalyst prepared above was characterized by TEM and surface scanning, as shown in the figure. Figure 2 As shown, a supported Pt-Bi₂O₃ catalyst was successfully prepared, with good Pt particle dispersion and uniform particle size, averaging 2.33 ± 0.40 nm. According to the calculation method in Table 1, the number of interface atoms N in each Pt particle... interface With the total number of atoms N T The proportion was 4.86%.

[0068] 0.0170 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate 65%, DHA selectivity 50%.

[0069] Example 5

[0070] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0071] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 5 times. The catalyst prepared above was characterized by TEM and surface scanning, as shown in the figure. Figure 3 As shown, a supported Pt-Bi₂O₃ catalyst was successfully prepared, with good Pt particle dispersion and uniform particle size, averaging 1.59 ± 0.28 nm. According to the calculation method in Table 1, the number of interface atoms N in each Pt particle... interface With the total number of atoms N T The proportion was 9.84%.

[0072] 0.0682 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate was 62%, and DHA selectivity was 82%.

[0073] Example 6

[0074] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0075] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 3 times. The catalyst prepared above was characterized by TEM and scanned. Figure 3 Similarly, it can be seen that a supported Pt-Bi2O3 catalyst was prepared, and the Pt particles have good dispersion and uniform particle size.

[0076] 0.0682 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate 63%, and DHA selectivity 45%.

[0077] Example 7

[0078] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0079] 0.2 g of the above-loaded auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively, and the deposition cycle was repeated 10 times. The catalyst prepared above was characterized by TEM and scanned. Figure 1 Similarly, it can be seen that a supported Pt-Bi2O3 catalyst was prepared, and the Pt particles have good dispersion and uniform particle size.

[0080] 0.100 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C for 2 h under normal pressure. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate was 97%, and DHA selectivity was 66%.

[0081] Example 8

[0082] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. Dry it in an oven at 110℃ for 15h. Mix 0.0824g of antimony trichloride solid, 0.0694g of citric acid, and 0.3611g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind it after drying, place it in a muffle furnace, raise the temperature to 250℃ at a rate of 5℃ / min, and calcine it at this temperature for 10min to obtain the Sb2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0083] 0.2 g of the above-mentioned supported auxiliary oxide was mixed with ethanol at a ratio of 12.5 mg: 1 ml to prepare an ethanol mixture. After ultrasonic treatment for 30 min, 1 ml of the mixture was evenly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were cleaned with nitrogen gas, and Pt precursor and O3 were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source of metallic Pt precursor MeCpPtMe3, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O3 were 1 s, 12 s, and 25 s, respectively. The deposition cycle was repeated 10 times to prepare a supported Pt-Sb2O3 structured catalyst with good Pt particle dispersion and uniform particle size.

[0084] 0.050 g of the catalyst prepared in this example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C under normal pressure for 6 h. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate was 90%, and DHA selectivity was 50%.

[0085] Comparative Example 1

[0086] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.1096g of bismuth nitrate pentahydrate solid, 0.0434g of citric acid, and 0.1130g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0087] 1 g of the above-loaded auxiliary oxide was placed in a crucible, and 4.604 ml of ultrapure water and 1.396 ml of a 0.1 g / ml (w / v) chloroplatinic acid hexahydrate mixture were added dropwise using a dropper, with continuous stirring by a glass rod. After the addition was complete, stirring was continued for half an hour, followed by natural aging at room temperature for 12 hours, drying in an oven at 110 °C for 12 hours, and grinding. After impregnation and drying, the catalyst was reduced in a tube furnace at 250 °C under a H2 reducing atmosphere for 2 hours, with the heating rate controlled at 5 °C / min. After reduction, the catalyst was naturally cooled to room temperature and then passivated by passing Ar / O2. The catalyst prepared above was characterized by TEM and surface scanning, as shown in the figure. Figure 4 As shown, a supported Pt-Bi₂O₃ catalyst was successfully prepared. The Pt loading in this catalyst is similar to that of Example 1, but the dispersibility and particle size uniformity of the Pt particles are lower compared to the example, with an average particle size of 3.63 ± 1.35 nm. According to the calculation method in Table 1, the number of interface atoms N in each Pt particle... interface With the total number of atoms N T The proportion was 2.09%.

[0088] 0.030 g of the catalyst prepared in this comparative example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C for 6 h under normal pressure. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate 55%, DHA selectivity 44%.

[0089] Comparative Example 2

[0090] 2 mmol of bismuth nitrate pentahydrate was added to 64 ml of tert-butanol and 16 ml of ethylene glycol, and the mixture was magnetically stirred for 3 hours followed by sonication for 30 minutes. The resulting solution was then transferred to a PTFE-lined stainless steel autoclave and calcined at 160 °C for 8 hours. After cooling, the solid was centrifuged and washed four times alternately with ultrapure water and ethanol. Following washing, the solid was dried in a vacuum drying oven at 60 °C (-0.1 MPa) for 8 hours to obtain solid Bi₂O₃, which was confirmed by XRD.

[0091] The above-mentioned loaded auxiliary oxide Bi₂O₃ was mixed with ethanol at a ratio of 20 mg: 1.5 ml to prepare an ethanol mixture. After ultrasonic treatment for 1 h, the mixture was uniformly coated onto a glass slide and placed in an atomic layer deposition (ALD) sample chamber. The sample chamber and tubing were purged with nitrogen gas, and Pt precursor and O₃ were alternately introduced sequentially. The ALD parameters were set as follows: using a room-temperature liquid source metal Pt precursor MeCpPtMe₃, the pulse, hold-up, and evacuation times for the precursor were 0.5 s, 12 s, and 25 s, respectively; the pulse, hold-up, and evacuation times for O₃ were 1 s, 12 s, and 25 s, respectively. The deposition cycle was repeated 10 times to obtain the Pt / Bi₂O₃ catalyst.

[0092] 0.030 g of the catalyst prepared in this comparative example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C for 6 h under normal pressure. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results were as follows: glycerol conversion rate 5%, and DHA selectivity 0%.

[0093] Comparative Example 3

[0094] 0.1387 g of bismuth nitrate pentahydrate solid was mixed with 1.4808 mL of chloroplatinic acid hexahydrate solution (0.1 g / mL). An equal volume of ethanol was then added, and the mixture was ultrasonically dispersed for 20 min to obtain a Pt-Bi precursor solution. 1 g of carbon nanotubes was weighed and placed in a crucible. The Pt-Bi precursor solution was then dropped onto the carbon nanotubes, followed by the addition of 10 mL of ethanol. The mixture was stirred until homogeneous and then ultrasonicated until all the solvent evaporated. The mixture was then aged at room temperature for 12 h, followed by drying at 80 °C for 12 h. The dried catalyst was then removed, ground, and set aside for later use.

[0095] The catalyst to be reduced was reduced at 600℃ for 12 h under a reducing atmosphere of 10% H2 + 90% Ar to obtain a Pt-Bi intermetallic compound catalyst. The heating rate was controlled at 5℃ / min. The reduced catalyst was then passivated by passing it through Ar / O2 for 30 min and then removed for use. The catalyst prepared in this comparative example was characterized by XRD, as shown below. Figure 5 As shown, XRD comparison reveals that the catalyst crystal form is a Pt1Bi1 intermetallic compound.

[0096] 0.075 g of the catalyst prepared in this comparative example was added to a three-necked flask along with 30.0 g of an aqueous glycerol solution (0.1 g glycerol / g water). The O2 flow rate was 150 mL / min, and the reaction was carried out at 60 °C under normal pressure for 6 h. Samples were continuously taken from the reaction mixture, filtered through a filter, and diluted 6 times with ultrapure water. The diluted samples were then analyzed by high-performance liquid chromatography (HPLC). The results showed that the glycerol conversion rate was 46%, and the selectivity for dihydroxyacetone was 53%.

[0097] Comparative Example 4

[0098] Take 5g of carbon nanotube carrier with closed ends, place it in 100ml of concentrated nitric acid, and reflux it three times in an oil bath at 100℃. After filtration, wash it thoroughly with ultrapure water. After drying in an oven at 110℃ for 15h, mix 0.0824g of bismuth nitrate pentahydrate solid, 0.0694g of citric acid, and 0.3611g of polyethylene glycol in 6ml of nitric acid solution and stir magnetically for 3.5h. Weigh 1g of the carbon nanotube treated with concentrated nitric acid and pour it into a crucible. Add the above mixed solution dropwise onto the carbon nanotube while stirring continuously with a glass rod. After all the solution has been added, stir for another half hour. Age at room temperature for 14h, dry in an oven at 110℃ for 12h, grind after drying, place in a muffle furnace, heat to 250℃ at a heating rate of 5℃ / min, and calcine at this temperature for 10min to obtain the Bi2O3 auxiliary oxide supported on the carbon nanotube carrier.

[0099] 1 g of the above-loaded auxiliary oxide was placed in a crucible, and 4.604 ml of ultrapure water and 1.396 ml of a 0.1 g / ml (w / v) mixture of chloroplatinic acid hexahydrate were added dropwise using a dropper. The glass rod was continuously stirred during the addition process. After the addition was completed, stirring was continued for half an hour, followed by natural aging at room temperature for 12 hours, drying in an oven at 110 °C for 12 hours, and grinding. After impregnation and drying, the catalyst was reduced in a tube furnace at 250 °C under a H2 reducing atmosphere for 2 hours, with the heating rate controlled at 5 °C / min. After the reduction was completed, the catalyst was naturally cooled to room temperature and then passivated by passing Ar / O2 to obtain the Pt / Bi2O3-CNTs catalyst.

[0100] 0.030 g of the catalyst prepared in this comparative example and 30.0 g of glycerol aqueous solution (0.02 g glycerol / g water) were placed in a three-necked flask. The flow rate of O2 was adjusted to 150 ml / min using a flow controller. The reaction was carried out at 60 °C for 6 h under normal pressure. Samples were taken at 1 h intervals after each reaction. After filtration, the samples were diluted 2 times with ultrapure water. The diluted samples were then analyzed by high performance liquid chromatography. The results are as follows: glycerol conversion rate 40%, DHA selectivity 25%.

[0101] The Pt loading in the catalysts prepared in the above embodiments and comparative examples of this application is not necessarily the same, and therefore the amount of catalyst added will not be the same when applied to the selective catalytic oxidation reaction of glycerol. However, the Pt content in the catalysts added in Comparative Examples 1-4 is consistent with the molar ratio of Pt content to glycerol in the reaction raw material, and is also consistent with the molar ratio of Pt content to glycerol in the catalysts added in Examples 1, 4, and 5, so the reaction results can be directly compared.

[0102] This application provides a detailed description, the purpose of which is to enable those skilled in the art to understand and implement the content of this application, but it should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be covered within the scope of protection of this application.

Claims

1. A Pt-MO catalyst with uniform interface structure for the selective catalytic oxidation of glycerol to produce DHA X A method for producing a catalyst, characterized by, Includes the following steps: (1) The carrier was pretreated with concentrated nitric acid; (2) mixing the assistant compound, the complexing agent, the solvent, and the pretreated carrier to obtain a mixture; aging, drying, and calcining the mixture to obtain a composite material loaded with an assistant oxide MO X , wherein the assistant oxide MO X is Bi2O3 or Sb2O3; (3) Pt is deposited on the calcined composite material using atomic layer deposition to obtain Pt-MO with Bi2O3 or Sb2O3 as auxiliary oxide. X Catalyst, namely Pt-Bi2O3 or Pt-Sb2O3 catalyst; In step (1), the carrier is a carbon carrier, selected from activated carbon, carbon black, carbon nanofibers, and carbon nanotubes with closed ends; In step (3), the composite material is dissolved in anhydrous ethanol and coated onto a glass slide; then, at an atomic layer deposition temperature of 200-400 °C, Pt precursor and O3 are alternately introduced sequentially, and the deposition cycle is repeated 1-25 times to prepare supported Pt-MO. X The catalyst uses a room-temperature liquid source Pt precursor, MeCpPtMe3, as the Pt raw material for deposition. The pulse, suffocation, and evacuation times of the Pt precursor are 0.1~1 s, 3~15 s, and 25~60 s, respectively. The pulse, suffocation, and evacuation times of O3 are 0.5~2 s, 3~15 s, and 25~60 s, respectively. The complexing agent is citric acid and polyethylene glycol.

2. The production method according to claim 1, characterized by, The auxiliary compound is a compound of metallic Bi or Sb, wherein the compound of metallic Bi is selected from bismuth acetate, bismuth nitrate pentahydrate, and bismuth chloride; the compound of metallic Sb is selected from antimony powder and antimony trichloride; and the solvent is a nitric acid solution.

3. The preparation method according to claim 1, characterized in that, In step (1), the carrier and concentrated nitric acid are mixed and condensed and circulated at a temperature of 80~120 ℃. After the circulation is completed, the mixture is filtered, washed, and repeated 2~5 times. Then it is dried at a temperature of 80~110 ℃ for 10~18 h.

4. The method of claim 1, wherein, In step (2), the auxiliary compound, complexing agent, and solvent are mixed and stirred for 2-5 h to obtain an auxiliary precursor solution; the auxiliary precursor solution is added dropwise to the carrier and stirred evenly, aged at room temperature for 10-18 h, and then dried at 80-110 ℃ for 10-18 h; subsequently, it is calcined in a muffle furnace at a heating rate of 1-5 ℃ / min, and isothermal calcined at a calcination temperature of 200-400 ℃ for 5-20 min to obtain the supported auxiliary oxide MO. X Composite materials.

5. The preparation method according to claim 4, characterized in that, The heating rate is 1.5~5 ℃ / min; the calcination temperature is 200~300 ℃; and the isothermal calcination time is 8~17 min.

6. The preparation method according to claim 5, characterized in that, The heating rate is 5 °C / min.

7. The preparation method according to claim 5, characterized in that, The calcination temperature is 250 ℃.

8. The preparation method according to claim 5, characterized in that, The constant temperature calcination time is 10 minutes.

9. The method of claim 1, wherein, The atomic layer deposition reaction temperature is 250~350℃, the pulse time of the Pt precursor is 0.3~0.8 s, the pulse time of the O3 is 0.8~1.5 s, the holding time of the Pt precursor and O3 is 8~12 s, the evacuation time of the Pt precursor and O3 is 25~50 s, and the number of deposition cycles is 3~20.

10. The method of claim 9, wherein, The atomic layer deposition reaction temperature is 270 °C.

11. The preparation method according to claim 9, characterized in that, The pulse duration of the Pt precursor is 0.5 s.

12. The method of claim 9, wherein, The pulse duration of the O3 is 1 s.

13. The preparation method according to claim 9, characterized in that, The holding time for the Pt precursor and O3 is 12 seconds.

14. The method of claim 9, wherein, The evacuation time for the Pt precursor and O3 is 25 seconds.

15. The preparation method according to claim 9, characterized in that, The deposition cycle is repeated 3 to 15 times.

16. Pt-MO prepared according to the process of any one of claims 1-15 X Use of the catalyst in the reaction of selective catalytic oxidation of glycerol to prepare DHA.

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