Composite carrier loaded bimetallic catalyst, preparation method and application thereof

Abstract

The application discloses a composite carrier loaded bimetallic catalyst and a preparation method and application thereof. The application takes mesoporous molecular sieve (SBA-15) as a matrix, and a CD-SBA-15 composite catalyst carrier with a thermally induced delayed fluorescence performance is prepared by a hydrothermal method, and a PdM / CD-SBA-15 composite catalyst is prepared by a photoreduction method under irradiation of a 365nm ultraviolet lamp. n M=Cu or Co or Ni, and n=0.5 or 1 or 2. The SBA-15 can effectively protect and disperse carbon dots, reduce aggregation of the carbon dots and delay fluorescence quenching, the CDs confined in the SBA-15 can promote rapid transfer of electrons between the two, and the synergistic effect between the two makes the composite material have excellent performance. In addition, the CDs also play a bridging role between the SBA-15 and the alloy PdM n , are beneficial to rapid transfer of electrons, and improve activity and stability of the catalyst. By adopting the catalyst, conversion rates of benzaldehyde and acetone are both 100%, and selectivity of 1,5-diphenyl-3-pentanone is more than 90%, which is an important aviation kerosene component synthesis intermediate and a chemical synthesis raw material.

Description

Technical Field

[0001] This invention belongs to the field of biomass energy catalysis, specifically relating to a composite support-supported bimetallic catalyst PdM n The preparation method of (M = Cu or Co or Ni, n = 0.5 or 1.0 or 2.0) / CDs-SBA-15 and its application in the catalytic condensation-hydrogenation deoxygenation of benzaldehyde and acetone to prepare aviation kerosene precursor. Background Technology

[0002] Rapid industrial development has led to a dramatic increase in energy consumption, and energy shortages have become a significant factor restricting industrial development and even social progress. In recent years, the rapid development of the aviation industry has presented new challenges to both the quality and quantity of aviation kerosene. Aviation kerosene is a petroleum product, mainly composed of hydrocarbon compounds of different fractions, including straight-chain alkanes, branched alkanes, cycloalkanes, and aromatics. Among these hydrocarbon compounds, chain alkanes with the same number of carbon atoms have a higher hydrogen-to-carbon ratio; the higher the hydrogen-to-carbon ratio, the higher its calorific value. Cycloalkanes have a lower hydrogen-to-carbon ratio and a lower calorific value; their main role in kerosene composition is to lower the fuel's pour point; the higher their content, the lower the pour point. Increasing the aromatic content can increase the fuel density; among alkanes with the same number of carbon atoms, aromatics have a higher volumetric calorific value. Therefore, to meet the combustion performance requirements of aviation kerosene, its component content needs to be blended to achieve suitable density, high calorific value, rapid, stable, and continuous complete combustion, while also meeting the low-temperature fluidity requirements of high-altitude flight.

[0003] With the depletion of fossil fuels, the development of biomass energy is considered an important way to effectively solve the energy crisis. Bio-jet fuel, specifically designed to meet the needs of the aviation industry, can be prepared in two ways: one is by directly hydrogenating and deoxygenating biomass macromolecules (such as cellulose, hemicellulose, and lignin) to produce hydrocarbon fuels; the other is by first using biomass platform compounds (such as guaiacol, phenol, furfural, benzaldehyde, and acetone) through carbon chain growth (such as aldol condensation, alkylation, and copper-based oxidation), followed by catalytic hydrogenation and deoxygenation. Currently, raw materials successfully converted into bio-jet fuel include waste animal and vegetable oils (gutter oil), agricultural and forestry waste, and algae. However, the method of producing bio-jet fuel using biomass platform compounds through carbon chain growth and hydrogenation and deoxygenation is still in its early stages. Compared to traditional jet fuel, bio-jet fuel can reduce CO2 emissions by 55%–92%, is renewable and sustainable, and requires no engine modification, offering significant environmental advantages.

[0004] Aromatic compounds are an important component of aviation kerosene. Due to their high carbon-hydrogen ratio, increasing their content can improve the volumetric calorific value and density of aviation kerosene. 1,5-Diphenyl-3-pentanone is an important chemical synthesis raw material with a wide range of applications: firstly, it has a distinctive aroma and is widely used in the synthesis of perfumes and fragrances; secondly, its symmetrical mirror-image structure makes it suitable as a raw material for the synthesis of important anticancer drugs, as a detection probe reagent, and as an organic solvent; thirdly, it has a long carbon chain and contains a two-molecule aromatic ring structure with a high carbon-hydrogen ratio, making it an important intermediate raw material for the synthesis of aromatic components in aviation kerosene. However, because 1,5-diphenyl-3-pentanone is mainly found naturally in agarwood, its content is low and extraction is difficult, resulting in high prices, and its artificial synthesis has been rarely studied. Based on the above problems, this invention proposes for the first time the artificial synthesis of 1,5-diphenyl-3-pentanone using the aldol condensation-hydrogenation deoxygenation of benzaldehyde and acetone, wherein the hydrogenation deoxygenation process utilizes PdM... n / CDs-SBA-15 composite catalyst.

[0005] SBA-15 is a regularly ordered, two-dimensional hexagonal molecular sieve mesoporous material with a uniform pore size distribution, typically in the range of 5–10 nm. Its characteristics include: 1. A large specific surface area, allowing for the loading of more active materials. The confinement effect of SBA-15 on carbon nanodots helps delay fluorescence quenching and improves photoreduction performance; 2. Compared to other molecular sieves (such as ZSM), it has thicker pore walls, which can improve the stability of CDs / SBA-15 composites. Doped ligands and active metal particles can be better immobilized in the ordered mesoporous channels. The larger pore structure also facilitates the adsorption of reactant molecules and the desorption of product molecules, increasing the catalytic reaction rate. However, there are currently no reports in the literature on the doping of carbon dots into the mesoporous channels of SBA-15. Because the pore structure of SBA-15 can effectively and rapidly promote the diffusion of reactant molecules, it allows PdM… n The / CDs-SBA-15 composite catalyst has great potential in biomass catalysis applications.

[0006] Based on the above problems, this invention provides a PdM composite material CDs-SBA-15, which uses CDs-modified SBA-15 as a carrier. n Preparation method of / CDs-SBA-15 composite catalyst and its application in the synthesis of aviation kerosene precursor by catalytic condensation-hydrogenation deoxygenation of benzaldehyde and acetone hydroxyl condensation. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a composite-supported bimetallic catalyst, its preparation method, and its application. The catalyst in question is PdM. nThe / CDs-SBA-15 composite catalyst was used to prepare a catalyst for the catalytic condensation-hydrodeoxygenation of benzaldehyde and acetone to prepare aviation kerosene precursor.

[0008] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0009] PdM n / CDs-SBA-15 composite catalyst, comprising: a support and an active metal supported on the support;

[0010] The carrier is a composite carrier;

[0011] Where M is Cu, Ni, or Co; n is 0.5, 1, or 2.

[0012] Preferably, the composite support comprises SBA-15 mesoporous molecular sieve and carbon dot CDs;

[0013] Preferably, the active metal is the noble metal Pd and the non-noble metal Cu, Co, or Ni, and the mass percentage of the active metal in the catalyst is 5-10%.

[0014] Another object of the present invention is to provide PdM n The preparation method of the / CDs-SBA-15 composite catalyst includes the following steps:

[0015] S1: SBA-15 pretreatment;

[0016] S2: Hydrothermal preparation of composite carrier CDs-SBA-15;

[0017] S3: Photoreduction method for preparing PdM n / CDs-SBA-15.

[0018] Preferably, in step S1, SBA-15 is ground, sieved, and placed in a muffle furnace and heated from 25°C at a heating rate of 5°C / min until the temperature reaches 400-900°C, and held at that temperature for 4-8 hours to remove organic impurities.

[0019] Preferably, in step S2, SBA-15 molecular sieve is uniformly dispersed in ultrapure water to form dispersion system A, glucose and urea are dissolved in ultrapure water to form solution B, solution B is added dropwise to solution A while continuously stirring, and then the mixed solution is transferred into a high-temperature and high-pressure reactor for full reaction. After cooling, it is taken out and obtained by centrifugation, filtration and dialysis to obtain CDs-SBA-15 composite carrier suspension.

[0020] Preferably, in solution A, the mass ratio of SBA-15 molecular sieve to ultrapure water is 1:80-150, and in solution B, the mass ratio of glucose, urea, to ultrapure water is 5:1-2:80-150. The stirring time is 6-10 hours, and the mixed solution is reacted in a high-temperature and high-pressure reactor at a temperature of 220-300℃ and a rotation speed of 300-500 r / min for 6-8 hours.

[0021] Preferably, in step S3, palladium acetate, copper acetate, cobalt nitrate, or nickel nitrate are dissolved in ultrapure water to form solution C. Under magnetic stirring, solution C is added dropwise to the CDs-SBA-15 composite carrier suspension, which is then irradiated under ultraviolet light and dialyzed to obtain PdM. n / CDs-SBA-15 composite catalyst, wherein M is Cu, Ni or Co; n is 0.5, 1 or 2; thus, a bimetallic catalyst supported on a composite support is obtained.

[0022] Preferably, the mass ratio of palladium acetate, copper acetate, cobalt nitrate, or nickel nitrate to ultrapure water is 1:0.5 to 2:8000 to 10000. The mixture is stirred and irradiated under a 365nm ultraviolet lamp, dialyzed, dried, and weighed for later use.

[0023] Another object of the present invention is to provide PdM n Application of / CDs-SBA-15 composite catalyst in the synthesis of 1,5-diphenyl-3-pentanone:

[0024] Preferably, the mass ratio of benzaldehyde, acetone and ultrapure water is 3:1 to 2:400 to 600, a high-temperature and high-pressure reactor is used, and the reaction time is 6 to 8 hours under the conditions of 90 to 160°C and hydrogen pressure of 2 to 5 MPa. The conversion rate of benzaldehyde and acetone is 100%, and the selectivity of 1,5-diphenyl-3-pentanone is 92.19%.

[0025] The beneficial effects of this invention are:

[0026] SBA-15 can effectively disperse carbon dots and delay their fluorescence quenching, while the carbon dots confined in SBA-15 can promote the rapid transfer of electrons from the molecular sieve to the carbon dot surface, thus improving the photoreduction performance of the carbon dots. Furthermore, the carbon dots act as a link between SBA-15 and PdM... n The bridging effect of bimetallic alloy nanoparticles and the abundance of functional groups on the surface of CDs facilitate the reaction of organic substrates in PdM nThe adsorption on the surface of the / CDs-SBA-15 catalyst enhances its activity and stability. The invention employs an aldol condensation-hydrogenation deoxygenation reaction of benzaldehyde and acetone to test the catalyst's activity. Results show that at 150℃ and 3MPa, the conversion rates of both benzaldehyde and acetone are 100%, and the selectivity for 1,5-diphenyl-3-pentanone exceeds 90%. This invention provides a method for the artificial synthesis of 1,5-diphenyl-3-pentanone, characterized by a wide availability of raw materials, a simple synthesis method, and high yield, effectively reducing the production costs of aviation kerosene and important chemical products. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram illustrating the preparation of the PdCu / CDs-SBA-15 catalyst and the generation principle of 1,5-diphenyl-3-pentanone according to the present invention.

[0029] Figure 2 These are the XRD patterns of the PdCu / CDs-SBA-15, PdCo / CDs-SBA-15, and PdNi / CDs-SBA-15 composite catalysts.

[0030] Figure 3 These are (a) TEM images and (b) HRTEM images of the CDs-SBA-15 composite vector.

[0031] Figure 4 These are the FT-IR spectra of SBA-15, CDs-SBA-15, and PdCu / CDs-SBA-15.

[0032] Figure 5 This is the mass-to-charge ratio diagram of 1,5-diphenyl-3-pentanone. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, 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 protection of the present invention.

[0034] Example 1

[0035] First, SBA-15 is ground and sieved, then placed in a muffle furnace for high-temperature calcination to remove organic impurities from its surface. The temperature is raised to 600–900°C at a rate of 5–10°C / min and held at this temperature for 4–5 hours before being removed for later use. Using an electronic balance, accurately weigh 0.1 g of SBA-15 molecular sieve and mix it with 10–20 mL of ultrapure water, denoted as solution A; weigh 0.5–1 g of glucose and 0.1–0.2 g of urea and dissolve them in 10 mL of ultrapure water, denoted as solution B; weigh 0.25–0.5 mmol of palladium acetate and 0.25–0.5 mmol of copper acetate, cobalt nitrate, or nickel nitrate and dissolve them in 10 mL of ultrapure water, denoted as solutions C1, C2, and C3.

[0036] First, add solution B to solution A under magnetic stirring and continue stirring and aging for 6-10 hours. Then, transfer the mixed solution into a high-temperature and high-pressure reactor and react it fully for 6-8 hours at 220-300℃ and 300-500 r / min. After cooling, remove the solution and obtain the CDs-SBA-15 composite catalyst support solution by centrifugation, filtration, and dialysis.

[0037] In the second step, under magnetic stirring, solution C was added dropwise to the carrier mixture obtained in the first step. The mixture was then irradiated under a 365nm UV lamp with stirring for 4–6 hours, followed by dialyzing for 72–96 hours to obtain PdM. n / CDs-SBA-15 composite catalyst.

[0038] Example 2

[0039] PdM n Application of / CDs-SBA-15 composite catalyst in the synthesis intermediates of key components of aviation kerosene:

[0040] Using a high-temperature, high-pressure reactor, the reaction was carried out at a temperature of 90–160°C and a hydrogen pressure of 3–5 MPa for 6–8 hours. The conversion rates of benzaldehyde and acetone were both 100%, and the selectivity for 1,5-diphenyl-3-pentanone was 92.19%. More examples are shown in the table below.

[0041]

[0042] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. PdM n / CDs-SBA-15 composite catalyst, characterized in that... include: The carrier and the active metal loaded on the carrier; The carrier is a composite carrier; Wherein, M is Cu, Ni, or Co; n is 0.5, 1, or 2; the composite support comprises SBA-15 mesoporous molecular sieve and carbon dot CDs; The specific preparation method is as follows: S1: SBA-15 pretreatment; S2: Hydrothermal preparation of composite carrier CDs-SBA-15; S3: PdM was prepared by photoreduction method n / CDs-SBA-15; In step S1, SBA-15 is ground, sieved, and placed in a muffle furnace. Starting from 25°C, it is heated at a heating rate of 5°C / min until the temperature reaches 400~900°C. The temperature is then maintained for 4~8 hours to remove organic impurities. In step S2, SBA-15 molecular sieve is uniformly dispersed in ultrapure water to form dispersion system A. Glucose and urea are dissolved in ultrapure water to form solution B. Solution B is added dropwise to solution A while continuously stirring. The resulting mixed solution is then transferred to a high-temperature and high-pressure reactor for full reaction. After cooling, the solution is removed and centrifuged, filtered, and dialyzed to obtain a CDs-SBA-15 composite carrier suspension. In dispersion system A, the mass ratio of SBA-15 molecular sieve to ultrapure water is 1:80~150. In solution B, the mass ratio of glucose, urea, and ultrapure water is 5:1~2:80~150. The stirring time is 6~10 hours. The mixed solution is reacted in a high-temperature and high-pressure reactor at a temperature of 220~300℃ and a rotation speed of 300~500 r / min for 6~8 hours.

2. The PdM according to claim 1 n / CDs-SBA-15 composite catalyst, characterized in that... The active metal is the noble metal Pd and the non-noble metal Cu, Ni or Co, and the mass percentage of the active metal in the catalyst is 5%-10%.

3. The PdM according to claim 1 n The method for preparing the / CDs-SBA-15 composite catalyst is characterized by, In step S3, palladium acetate, copper acetate, cobalt nitrate, or nickel nitrate are dissolved in ultrapure water to form solution C. Under magnetic stirring, solution C is added dropwise to the CDs-SBA-15 composite carrier suspension. The suspension is then irradiated under ultraviolet light and dialyzed to obtain PdM. n / CDs-SBA-15 composite catalyst, wherein M is Cu, Ni or Co; n is 0.5, 1 or 2; thus, a bimetallic catalyst supported on a composite support is obtained.

4. The PdM according to claim 3 n The method for preparing the / CDs-SBA-15 composite catalyst is characterized by, The mass ratio of palladium acetate, copper acetate, cobalt nitrate, or nickel nitrate to ultrapure water is 1:0.5~2:8000~10000. The mixture is stirred and irradiated under a 365nm ultraviolet lamp, dialyzed, dried, and weighed for later use.

5. The PdM according to any one of claims 1-4 n The application of the / CDs-SBA-15 composite catalyst in the synthesis of 1,5-diphenyl-3-pentanone is characterized by... The application method is as follows: using a high temperature and high pressure reactor, under the conditions of temperature 90~160℃ and hydrogen pressure 2~5MPa, the reaction time is 6~8h. The conversion rate of benzaldehyde and acetone is 100%, and the selectivity of 1,5-diphenyl-3-pentanone is 92.19%.

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