Method and application of C60-modified black phosphorus-modified aluminum-supported palladium-based catalyst

Abstract

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Description

Technical Field

[0001] The present invention relates to the technical field of black phosphorus materials, in particular to a C 60 The invention discloses a preparation method and application of modified black phosphorus for modifying aluminum-supported palladium-based catalysts. Background Art

[0002] Hydrogen peroxide, commonly known as hydrogen peroxide, has become a key fine chemical raw material in the chemical industry in recent years. Its oxidation reaction products are solely water and oxygen, making it one of the cleanest and greenest chemicals, widely used in textile and papermaking, wastewater treatment, electronics, and aerospace. The anthraquinone method is commonly used in industry to produce hydrogen peroxide, using an aluminum-supported palladium catalyst (Pd / Al2O3). However, large-scale production of hydrogen peroxide using this method incurs high metal costs. Modifying aluminum-supported palladium catalysts with black phosphorus to enhance hydrogen efficiency is one effective approach to reducing metal costs.

[0003] As a two-dimensional material, black phosphorus has a layered structure similar to graphite. The atomic layers are bound by van der Waals forces and are easily peeled off into single-layer nanosheets. Black phosphorus has many properties that other two-dimensional materials do not have, such as a band gap (0.3 to 2.0 eV) that can be adjusted with the number of layers, a high electron mobility (1000 cm 2 V -1 s -1 ) and the bipolar transport properties and unique in-plane anisotropy of few-layer black phosphorus. These unique properties make black phosphorus widely used in many fields, such as field-effect transistors, optoelectronic devices, energy conversion devices and biomedicine. In addition, black phosphorus has a pair of lone pairs of electrons exposed on the surface of the phosphorus atoms, which can interact with the empty metal orbitals, thereby changing the electronic structure and catalytic properties of the metal catalyst. However, the lone pairs of electrons on the phosphorus atoms easily react with the surrounding oxygen and continue to form phosphoric acid degradation products in the presence of water. In addition, the phosphorus atoms on the edge of black phosphorus are more active than those on the surface and are more prone to chemical reactions. This seriously damages the electronic and physical properties of black phosphorus, thereby restricting the practical application of black phosphorus.

[0004] C 60 It is a zero-dimensional material that is very stable to light, oxygen and water, and has strong electron-accepting ability and rapid electron transfer performance. Its hybridization with two-dimensional materials can change the physical / chemical properties of two-dimensional materials and, in most cases, improve their performance and application range, thereby broadening their applications. 60 Covalent modification of nano-black phosphorus constrains the lone pair electrons on the black phosphorus surface, thereby improving the stability of black phosphorus and giving the black phosphorus-modified metal catalyst more stable performance and longer life. Summary of the Invention

[0005] Aiming at the problem that the performance of the modified aluminum-supported palladium-based catalyst decreases due to the oxidative decomposition of black phosphorus, the present invention provides a C 60 Method for modifying aluminum-supported palladium-based catalyst by modified black phosphorus, by C 60 By constraining the lone pair electrons in black phosphorus and reducing their contact with oxygen, the stability and life of the catalyst can be improved.

[0006] In order to solve the above technical problems, the technical solutions involved in the present invention are as follows:

[0007] A C 60 The method for modifying aluminum-supported palladium-based catalyst with modified black phosphorus comprises the following steps:

[0008] S1. Using ball milling method to grind black phosphorus block into black phosphorus powder of a certain particle size;

[0009] S2. Evenly dispersing the black phosphorus powder in a solvent containing a surfactant, and ultrasonically crushing the powder in an ice bath to obtain a black phosphorus dispersion; subjecting the black phosphorus dispersion to high-speed centrifugation, and collecting the supernatant as the nano-black phosphorus dispersion;

[0010] S3, C 60 Add to the nano black phosphorus dispersion and ultrasonically crush under ice bath to obtain nano black phosphorus-C 60 dispersion;

[0011] S4, the aluminum-supported palladium-based catalyst after drying and dehydration is used to 60 The dispersion is modified, dried and calcined to obtain a modified aluminum-supported palladium-based catalyst.

[0012] In some preferred embodiments, as described in step S1, the volume of the ball mill jar is 50 mL to 4 L; the material of the ball mill jar and the grinding balls is any one or more of stainless steel, agate, corundum, tungsten carbide, nylon, zirconium oxide, polytetrafluoroethylene, and polyurethane; the diameter of the grinding balls is 3 to 40 mm; the ball mill speed is 50 to 500 r / min; and the ball-to-material ratio is 1:1 to 100:1.

[0013] In some preferred embodiments, in step S2, the surfactant is selected from one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltriethylammonium bromide, octadecyldimethylammonium chloride, octadecyltrimethylammonium bromide, Pluronic F127, polyvinylpyrrolidone, sodium lauryl sulfate and sodium dodecylbenzenesulfonate, and the content of the surfactant is 0.1 wt% to 10 wt%; the solvent is selected from one or more of deionized water, N-methylpyrrolidone, N-vinylpyrrolidone, N-cycloethylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropyl alcohol, tert-butanol, acetone and 2-pentanone.

[0014] In some preferred embodiments, in step S2, the ice bath temperature is 0-15° C.; the ultrasonication time is 1-72 h; the centrifugation time is 5-30 min; and the centrifugal speed is 2000-12000 r / min.

[0015] In some preferred embodiments, in step S3, C 60 The method is pre-dispersed in a solvent, wherein the solvent is selected from one or more of deionized water, N-methylpyrrolidone, N-vinylpyrrolidone, N-cycloethylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropanol, tert-butanol, acetone and 2-pentanone; the ice bath temperature is 0 to 15° C.; and the ultrasonic time is 1 to 72 hours.

[0016] In some preferred embodiments, in step S3, C 60 The dispersion is slowly added into the nano black phosphorus dispersion, wherein C 60 The content is 0.1wt% to 10wt% of black phosphorus.

[0017] In some preferred embodiments, as described in step S4, the aluminum-supported palladium-based catalyst is in the shape of small balls with a particle size of 2 to 5 mm and a palladium content of 0.1 wt% to 0.4 wt%; the drying method is one or more of electric forced air drying, inert atmosphere drying and vacuum drying, and the drying temperature is 80 to 200°C; the calcination temperature is 200 to 450°C, the calcination time is 2 to 8 hours, and the calcination atmosphere is nitrogen or argon.

[0018] In some preferred embodiments, in step S4, the nano black phosphorus-C 60 The dispersion was impregnated into the alumina palladium-based catalyst in equal volumes by overnight soaking or spraying.

[0019] In some preferred embodiments, the spray modification is performed with the combined assistance of a spray pot and a multifunctional mixer.

[0020] In some preferred embodiments, the mass ratio of black phosphorus to aluminum-supported palladium-based catalyst is 1:100 to 1:1000.

[0021] The present invention provides the C 60 A preparation method for a modified black phosphorus-modified aluminum-supported palladium-based catalyst and its application in the hydrogenation of anthraquinone to produce hydrogen peroxide.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a C 60 A method and application of modified black phosphorus to modify aluminum-supported palladium-based catalysts. The lone pair electrons of black phosphorus fill the empty orbitals of palladium metal, adjusting the electronic structure of palladium metal and enhancing the catalytic activity of the catalyst, thereby reducing the amount of palladium metal used.

[0024] C is very stable to light, oxygen and water. 60 Nano-black phosphorus was modified using C 60 The strong electron-accepting ability and rapid electron transfer performance constrain the lone pair electrons in nano-black phosphorus that are easily oxidized, thereby improving the stability of nano-black phosphorus.

[0025] The present invention has the characteristics of high efficiency, simplicity, green and pollution-free preparation process, is suitable for large-scale preparation of industrial catalysts, and has high industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Figure 1 shows the actual state of the catalyst before and after modification in Example 1. After modification, the color of the catalyst changes from yellow in Figure A to dark brown in Figure B, and the surface is smooth.

[0027] Figure 2 Pd / Al2O3-BP / C prepared in Example 1 60 -6 and Pd / Al2O3 XRD patterns, the main component is Al2O3, because Pd, BP and C 60 The content is relatively small and no corresponding diffraction peak is shown. The two spectra are completely indistinguishable, indicating that a small amount of BP / C 60 The structure of the modified catalyst was not destroyed.

[0028] Figure 3 Pd / Al2O3-BP / C prepared in Example 1 60 -6 EDS diagram, the sample contains five elements: P, Pd, C, O and Al, among which the main elements are O and Al.

[0029] Figure 4 Pd / Al2O3-BP / C prepared in Example 1 60 The comparison of the hydrogen efficiency performance of -16 and Pd / Al2O3-BP shows that the modified black phosphorus has obvious improvements in hydrogen efficiency, stability and lifespan. DETAILED DESCRIPTION

[0030] The application of the present invention is further illustrated below with reference to specific examples. The following examples are for illustrative purposes only and are not to be construed as limiting the present invention. Unless otherwise specified, the reagents and raw materials used in the following examples are conventional commercially available or commercially available reagents; unless otherwise specified, the equipment used in the following examples is conventionally used in the art.

[0031] Example 1

[0032] S1. Add 10 g of block black phosphorus and 200 g of 5 mm diameter agate balls to a 250 mL agate ball mill. Set the rotation speed to 200 rpm, rotate for 30 min and rest for 1 min, and mill for a total of 24 h to obtain black phosphorus powder.

[0033] S2. Weigh 500 mg of the black phosphorus powder obtained in S1 into a wide-mouth bottle, then add 100 mL of anhydrous ethanol to disperse the powder. Transfer the powder to an ultrasonic cell disruptor set at 4°C and sonicate for 24 hours. Centrifuge the resulting suspension at 3000 rpm for 15 minutes, and collect the supernatant as the nano-black phosphorus dispersion.

[0034] S3, 16.8 mg C 60 (accounting for 8% of the mass of black phosphorus) was dispersed in a certain amount of anhydrous ethanol (so that the total volume of the final dispersion was 100 mL), and C 60 The dispersion was slowly added to the nano black phosphorus dispersion obtained in S2, and then transferred to an ultrasonic cell disruptor with an ice bath temperature of 4°C for 12 h to obtain nano black phosphorus-C 60 dispersion.

[0035] S4, drying the commercially purchased aluminum-supported palladium catalyst in an electric heated forced air drying oven at 130°C for 6 hours. 60 The dispersion was sprayed with a spray bottle with the aid of a multifunctional mixer to impregnate an equal volume of the aluminum-supported palladium-based catalyst, wherein the mass ratio of black phosphorus to aluminum-supported palladium-based catalyst was 1:1000. The impregnated catalyst was then transferred to an electric blast drying oven and dried at 100°C for 6 hours. The dried catalyst was transferred to a tubular furnace under a nitrogen atmosphere and calcined at 280°C for 4 hours to obtain C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -1.

[0036] The modified catalyst was prepared with reference to Example 1, except that the C 60 4% of the mass of black phosphorus, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -2.

[0037] The modified catalyst was prepared by referring to Example 1, except that the C 60 2% of the mass of black phosphorus, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -3.

[0038] The modified catalyst was prepared with reference to Example 1, except that the C 60 1% of the mass of black phosphorus, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -4.

[0039] Example 2

[0040] S1. Add 10 g of block black phosphorus and 200 g of 5 mm diameter agate balls to a 250 mL agate ball mill. Set the rotation speed to 200 rpm, rotate for 30 min and rest for 1 min, and mill for a total of 24 h to obtain black phosphorus powder.

[0041] S2. Weigh 50 mg of hexadecyltrimethylammonium bromide and dissolve it in a wide-mouth glass bottle filled with 100 mL of deionized water. Weigh 500 mg of the black phosphorus powder obtained in S1 and add it to the jar. Transfer the powder to an ultrasonic cell disruptor set at an ice bath temperature of 4°C and sonicate for 24 hours. Centrifuge the resulting suspension at 3000 rpm for 15 minutes, and collect the supernatant as the nano-black phosphorus dispersion.

[0042] S3, 21mg C 60 Disperse in a certain amount of deionized water (make the total volume of the final dispersion 100mL), and stir C 60 The dispersion was slowly added to the nano black phosphorus dispersion obtained in S2, and then transferred to an ultrasonic cell disruptor with an ice bath temperature of 4°C for 12 h to obtain nano black phosphorus-C 60 dispersion.

[0043] S4, drying the commercially purchased aluminum-supported palladium catalyst in an electric heated forced air drying oven at 130°C for 6 hours. 60The dispersion was sprayed with a spray bottle with the aid of a multifunctional mixer to impregnate an equal volume of the aluminum-supported palladium-based catalyst, wherein the mass ratio of black phosphorus to aluminum-supported palladium-based catalyst was 1:1000. The impregnated catalyst was then transferred to an electric blast drying oven and dried at 100°C for 6 hours. The dried catalyst was transferred to a tubular furnace under a nitrogen atmosphere and calcined at 280°C for 4 hours to obtain C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -5.

[0044] The modified catalyst was prepared by referring to Example 4, except that the surfactant was hexadecyltriethylammonium chloride, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -6.

[0045] The modified catalyst was prepared by referring to Example 4, except that the surfactant was octadecyltrimethylammonium bromide, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -7.

[0046] The modified catalyst was prepared by referring to Example 4, except that the surfactant was Pluronic F127, and C 60 Modified black phosphorus-modified aluminum-supported palladium catalyst Pd / Al2O3-BP / C 60 -8.

[0047] Example 3

[0048] S1. Add 10 g of block black phosphorus and 200 g of 5 mm diameter agate balls to a 250 mL agate ball mill. Set the rotation speed to 200 rpm, rotate for 30 min and rest for 1 min, and mill for a total of 24 h to obtain black phosphorus powder.

[0049] S2. Weigh 500 mg of the black phosphorus powder obtained in S1 into a wide-mouth bottle, then add 100 mL of anhydrous ethanol to disperse the powder. Transfer the powder to an ultrasonic cell disruptor set at 4°C and sonicate for 24 hours. Centrifuge the resulting suspension at 3000 rpm for 15 minutes, and collect the supernatant as the nano-black phosphorus dispersion.

[0050] S3. Disperse 16.8 mg of graphene (8% of the mass of black phosphorus) in a certain amount of anhydrous ethanol (so that the total volume of the final dispersion is 100 mL), slowly add the graphene dispersion to the nano black phosphorus dispersion obtained in S2 under stirring, and transfer it to an ultrasonic cell disruptor with an ice bath temperature of 4°C for 12 hours of ultrasonic treatment to obtain a nano black phosphorus-graphene dispersion.

[0051] S4. Dry the commercially purchased aluminum-supported palladium-based catalyst in an electric blast drying oven at 130°C for 6 hours. The nano black phosphorus-graphene dispersion obtained in S3 is sprayed on the aluminum-supported palladium-based catalyst in equal volumes by spraying with the aid of a multifunctional mixer, wherein the mass ratio of black phosphorus to aluminum-supported palladium-based catalyst is 1:1000. The impregnated catalyst is then transferred to an electric blast drying oven and dried at 100°C for 6 hours. The dried catalyst is transferred to a tubular furnace under a nitrogen atmosphere and calcined at 280°C for 4 hours to obtain a graphene-modified black phosphorus-modified aluminum-supported palladium-based catalyst Pd / Al2O3-BP / GPE.

[0052] The modified catalyst was prepared with reference to Example 3, except that carbon fiber was used to modify black phosphorus to obtain a carbon fiber-modified black phosphorus-modified aluminum-supported palladium-based catalyst Pd / Al2O3-BP / CF.

[0053] The modified catalyst was prepared with reference to Example 3, except that carbon nanotubes were used to modify black phosphorus to obtain a carbon nanotube-modified black phosphorus-modified aluminum-supported palladium-based catalyst Pd / Al2O3-BP / CNT.

[0054] The modified catalyst was prepared with reference to Example 3, except that carbon aerogel was used to modify black phosphorus to obtain a carbon aerogel-modified black phosphorus-modified aluminum-supported palladium-based catalyst Pd / Al2O3-BP / CA.

[0055] The hydrogen efficiency of the catalyst was evaluated using a fixed-bed pilot plant: 200g of catalyst was loaded into a hydrogenation tower, the fixed bed was purged with N2, and then reduced at 60°C and 0.2Mpa H2 for 2h. A working solution (made by mixing C9 aromatics and trioctyl phosphate in a ratio of 75:25, followed by the addition of 2-ethylanthraquinone, with a concentration of 2-ethylanthraquinone of 120g / L) was then pumped in for reaction. Every 4h, 5mL of the hydrogenation solution was taken, and 20mL of C9 heavy aromatics, 100mL of pure water, and 4mL of phosphoric acid were added to it, followed by the introduction of oxygen for complete oxidation. Finally, the resulting aqueous solution containing hydrogen peroxide was titrated with a standard concentration of potassium permanganate solution to calculate the hydrogen efficiency.

[0056] Table 1 Complete oxidation time of black phosphorus dispersion under visible light and oxygen conditions

[0057] Serial number Black phosphorus dispersion liquid Complete oxidation time (day) 1 <![CDATA[BP / C 60 -1]]> 95 2 <![CDATA[BP / C 60 -2]]> 78 3 <![CDATA[BP / C 60 -3]]> 67 4 BP / C 60 -4]]> 53 5 <![CDATA[BP / C 60 -5]]> 86 6 <![CDATA[BP / C 60 -6]]> 83 7 <![CDATA[BP / C 60 -7]]> 91 8 <![CDATA[BP / C 60 -8]]> 87 9 BP / GPE 50 10 BP / CF 41 11 BP / CNT 43 12 BP / CA 41 13 BP (comparative example) 40

[0058] Table 2 Hydrogen efficiency and palladium content (ICP-AES) of the embodiments and comparative examples

[0059]

[0060]

Claims

1. A C 60 The method for preparing a modified black phosphorus-modified aluminum-supported palladium-based catalyst is characterized in that: The process of filling the empty orbitals of palladium metal with the lone pair electrons of black phosphorus, adjusting the electronic structure of palladium metal, enhancing the catalytic activity of the catalyst, and reducing the amount of palladium metal used comprises the following steps: S1. Using ball milling method to grind black phosphorus block into black phosphorus powder of a certain particle size; S2. Evenly dispersing the black phosphorus powder in a solvent containing a surfactant, and ultrasonically crushing the powder in an ice bath to obtain a black phosphorus dispersion; subjecting the black phosphorus dispersion to high-speed centrifugation, and collecting the supernatant as the nano-black phosphorus dispersion; S3, under stirring, C 60 The dispersion was slowly added to the nano-black phosphorus dispersion, which was transferred to an ultrasonic cell disruptor at an ice bath temperature of 4°C and ultrasonicated for 12 h to prepare a nano-black phosphorus-C60 dispersion, in which the content of C60 was 1 wt%, 2 wt%, 4 wt% or 8 wt% of the black phosphorus; S4, the aluminum-supported palladium-based catalyst after drying and dehydration is used to 60 The dispersion was modified and dried and calcined to obtain C 60 Modified black phosphorus-modified aluminum-supported palladium-based catalyst.

2. The preparation method according to claim 1, characterized in that In the ball milling method of step S1, the ball milling jar and the grinding balls are made of any one or more of stainless steel, agate, corundum, tungsten carbide, nylon, zirconium oxide, polytetrafluoroethylene, and polyurethane; the diameter of the grinding balls is 3 to 40 mm; the ball milling speed is 50 to 500 r / min; and the ball-to-material ratio is 1:1 to 100:

1.

3. The preparation method according to claim 1, characterized in that In step S2, the surfactant is selected from one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltriethylammonium bromide, octadecyltrimethylammonium bromide, Pluronic F127, polyvinylpyrrolidone, sodium lauryl sulfate and sodium dodecylbenzenesulfonate, and the content of the surfactant is 0.1wt%~10wt%; the solvent is selected from one or more of N-methylpyrrolidone, N-vinylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropyl alcohol, tert-butanol, acetone and 2-pentanone.

4. The preparation method according to claim 1, characterized in that In step S2, the ice bath temperature is 0-15°C; the ultrasonic time is 1-72 h; the centrifugation time is 5-30 min, and the centrifugal speed is 2000-12000 r / min.

5. The preparation method according to claim 1, characterized in that In step S3, C 60 Pre-dispersed in solvent to obtain C 60 The dispersion, wherein the solvent is selected from one or more of deionized water, N-methylpyrrolidone, N-vinylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropanol, tert-butanol, acetone and 2-pentanone.

6. The preparation method according to claim 1, characterized in that In step S4, the aluminum-supported palladium-based catalyst is in the shape of a sphere with a particle size of 2 to 5 mm and a palladium content of 0.1 wt% to 0.4 wt%; the drying method is one of electric blast drying, inert atmosphere drying, and vacuum drying, and the drying temperature is 80 to 200 ° C; the calcination temperature is 200 to 450 ° C, the calcination time is 2 to 8 h, and the calcination atmosphere is nitrogen or argon.

7. The preparation method according to claim 1, characterized in that In step S4, the modification method is to convert nano black phosphorus-C 60 The dispersion was impregnated into the aluminum-supported palladium-based catalyst in equal volumes by overnight immersion or spraying.

8. The preparation method according to claim 7, characterized in that The mass ratio of black phosphorus to aluminum-supported palladium-based catalyst is 1:100~1:1000.

9. C obtained by the preparation method according to any one of claims 1 to 8 60 Application of modified black phosphorus-modified aluminum-supported palladium-based catalyst in catalytic anthraquinone hydrogenation to produce hydrogen peroxide.

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