Process for the preparation of a catalyst and use for total hydrogenation of polycyclic aromatic hydrocarbons

Abstract

The application discloses a preparation method of a catalyst, which comprises the following steps: (1) uniformly mixing a titanium source and a structure directing agent to obtain an aging solution; (2) hydrothermally crystallizing the aging solution; (3) calcining the solid substance; (4) preparing platinum nanoparticles; (5) preparing a ruthenium source into an aqueous solution; (6) uniformly mixing the solid substance and the platinum nanoparticles and drying to obtain a solid substance; (7) washing the solid substance with ethanol, then dispersing the solid substance into water, adding the aqueous solution of the ruthenium source, obtaining a solid substance, and then reducing the solid substance; thus the catalyst is obtained. The application further discloses a use of the catalyst prepared by the preparation method for obtaining fuel through one-step reaction of polycyclic aromatic hydrocarbons.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic catalytic synthesis, and particularly relates to a preparation method of a catalyst and a method for synthesizing high-energy-density heat-absorbing aviation fuel through one-step full hydrogenation conversion of polycyclic aromatic hydrocarbons. BACKGROUND

[0002] The polycyclic aromatic hydrocarbon hydrogenation reaction is a strong exothermic reversible reaction, and the number of molecules decreases, so the conversion rate is limited by the thermodynamic equilibrium. Therefore, it has a thermodynamic advantage at low temperature, which is beneficial to the deep hydrogenation of polycyclic aromatic hydrocarbons. At the same time, low temperature is also conducive to the generation of cis-saturated isomers. The catalyst plays an important role in the polycyclic aromatic hydrocarbon hydrogenation reaction, and the hydrogenation performance of the polycyclic aromatic hydrocarbon hydrogenation catalyst mainly depends on the distribution and state of the active center. In order to improve the catalytic activity, the catalyst needs to be reasonably designed. Non-noble metals have the advantages of low cost and strong resistance to poisoning, and are commonly used in industrial hydrogenation catalysts. Non-noble metals are usually two or more metals together as active centers to improve activity, or non-metals such as C, N, P, S, etc. are doped to obtain similar activity to noble metals; metal sulfide catalysts such as NiWS, CoMoS or NiMoS on Al2O3 are the earliest to be applied to aromatic saturation reaction, and their catalytic performance has been comprehensively understood (Energy & Fuels, 2019, 33(4): 2810-2838). Sulfided metals can only achieve deep hydrogenation of polycyclic aromatic hydrocarbons under harsh conditions of high operating temperature and hydrogen pressure due to their weak turnover frequency. Currently, the overall hydrogenation activity of non-noble metal catalysts is not high, and they often need to operate at high temperature and high pressure, which requires high equipment and high energy consumption.

[0003] In the catalytic hydrogenation reaction of polycyclic aromatic hydrocarbons, noble metals (Pd, Pt, Ru, Rh, etc.) have high activity and can achieve deep hydrogenation under relatively mild conditions, and have shown great application potential in heterogeneous catalysis. However, under low temperature conditions, a long reaction time is needed to achieve complete conversion of the raw material, indicating that the catalytic activity of the catalyst is still insufficient, and the high resonance energy of polycyclic aromatic hydrocarbons needs to be further overcome to improve the catalytic activity of the catalyst at low temperature; therefore, the state of the metal needs to be further adjusted. In the past few decades, bimetallic catalysts have attracted widespread attention because metal nanoparticles (NPs) have great flexibility in adjusting the surface geometry and electronic structure compared with single-metal catalysts, which significantly affects the adsorption strength of the reactants and the activation energy, thereby affecting the activity and selectivity of the catalyst (Journal of the American Chemical Society, 2017, 139(6): 2122-2131.). Based on this, how to reasonably design bimetallic catalysts is still the key to preparing high-activity catalysts. SUMMARY

[0004] In order to solve the above-mentioned deficiencies and shortcomings of the prior art, the present application prepares a nano-TiO2 loaded bimetallic Ru and Pt catalyst (RuPt x The preparation method of the catalyst of the present application is prepared by using tetrabutyl titanate as the titanium source, chloroplatinic acid hexahydrate as the platinum source, and ruthenium chloride as the ruthenium source in the process of preparing titanium dioxide nanoparticles; and the RuPt x bimetallic catalyst is loaded on nano-TiO2 (RuPt x / TP); the introduction of nano-Pt forms interaction with Ru, and the synergistic effect of the two enhances the hydrogenation activity of the catalyst, which is successfully applied to the use of the catalyst in the catalytic reaction of one-step hydrogenation conversion of polycyclic aromatic hydrocarbons to synthesize high-energy density heat-absorbing aviation fuel, and increases the hydrogenation activity of the catalyst.

[0005] The technical scheme of the present application is as follows:

[0006] The present application discloses a preparation method of a catalyst, comprising the following steps:

[0007] (1) uniformly mixing a titanium source and a structure directing agent to obtain an aging solution;

[0008] (2) hydrothermally crystallizing the aging solution, then filtering and drying the solid to obtain a solid;

[0009] (3) calcining the solid obtained in step (2);

[0010] (4) dissolving a platinum source and a base in ethylene glycol to obtain platinum nanoparticles by reduction;

[0011] (5) preparing a ruthenium source into an aqueous solution;

[0012] (6) adding the solid obtained in step (3) into deionized water, then adding the platinum nanoparticles in step (4), uniformly mixing and drying at a certain temperature to obtain a solid;

[0013] (7) washing the solid obtained in step (6) with ethanol, then dispersing it into water, adding the aqueous solution of the ruthenium source in step (5), uniformly mixing and drying at a certain temperature to obtain a solid, and then reducing it in a H2 / Ar atmosphere; thus the catalyst is obtained.

[0014] Preferably, the titanium source in step (1) is tetrabutyl titanate, and the structure directing agent is acetic acid; the volume ratio of tetrabutyl titanate to acetic acid is 1: (3-5), preferably 1:4.

[0015] Preferably, the hydrothermal crystallization condition in step (2) is 180-220℃ for 12-36h; more preferably 200℃ for 24h.

[0016] Preferably, the calcination temperature of step (3) is 300-500℃, and the calcination time is 2-6h; preferably 400℃, 4h.

[0017] Preferably, the platinum source in step (4) is chloroplatinic acid hexahydrate, and the base is sodium hydroxide; the reduction temperature is 140-180℃, preferably 160℃; preferably the amount of chloroplatinic acid hexahydrate is 1g, and the amount of sodium hydroxide is 1g, and the amount of ethylene glycol is 100mL.

[0018] Preferably, the ruthenium source in step (5) is ruthenium chloride.

[0019] Preferably, the molar ratio of ruthenium in the ruthenium source aqueous solution to platinum in the solid in step (7) is 1:(0.05-0.20), preferably 1:0.13.

[0020] Preferably, the reduction temperature of step (7) is 300-500℃, preferably 400℃.

[0021] The second aspect of the present application discloses the use of the catalyst prepared by the preparation method for preparing high-energy-density fuel by catalyzing polycyclic aromatic hydrocarbons in one step at low temperature; the high-energy-density fuel is one or more of perhydroacenaphthylene, perhydrofluorene, decalin and perhydroanthracene.

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

[0023] 1. The preparation method of the present application prepares RuPt x / TP bimetallic catalyst, the formation of Ru-Pt interface causes changes in the electronic structure of Ru and Pt, the electron transfer of Ru to Pt, resulting in a decrease in the electron density of Ru, and the interaction of Ru and Pt with the carrier TiO2 respectively, increasing the hydrogenation activity of the catalyst. Among them, RuPt 0.13 / TP is the most suitable catalyst

[0024] 2. The RuPt x / TP bimetallic catalyst prepared by the preparation method of the present application is used for the one-step hydrogenation of polycyclic aromatic hydrocarbons to synthesize high-energy-density fuel, which can overcome the high resonance energy of polycyclic aromatic hydrocarbons, and catalyze the hydrogenation saturation of polycyclic aromatic hydrocarbons at near room temperature with high efficiency, while realizing high selectivity of cis products. The catalyst of the present application realizes the purpose of preparing high-energy-density aviation fuel by one-step hydrogenation saturation of polycyclic aromatic hydrocarbons at low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the Raman spectrum of the catalyst prepared in Examples 1-3.

[0026] Figure 2 is the X-ray diffraction (XRD) pattern of the catalyst prepared in Examples 1-4.

[0027] Figure 3 X-ray photoelectron spectroscopy (XPS) patterns of the catalysts prepared in Examples 1-3. DETAILED DESCRIPTION

[0028] The present application will be described in detail below with specific embodiments. These examples are only used to illustrate the present application, and are not used to limit the scope of the present application. The embodiments in the examples are only preferred solutions, but the present application is not limited to the preferred solutions.

[0029] Example 1: The amount of nano-Pt added was 0.08:1 in molar ratio with Ru.

[0030] (1) 5 mL of tetrabutyl titanate was added to 20 mL of glacial acetic acid at room temperature with stirring; after stirring for 30 min, it was transferred to a 100 mL polytetrafluoro liner, and hydrothermal synthesis was carried out at 200°C for 24 h;

[0031] (2) After natural cooling to room temperature, the obtained sample was washed with anhydrous ethanol three times, and the powder was obtained by drying at 80°C overnight;

[0032] (3) The obtained powder was collected, ground, and calcined in a muffle furnace at a temperature increasing rate of 5°C·min -1 -1 for 4 h at 400°C; the sample was named TiO2-NP;

[0033] (4) In a three-necked flask, 100 mL of ethylene glycol was added, 1 g of sodium hydroxide was added at room temperature with stirring until completely dissolved, and then 1 g of chloroplatinic acid hexahydrate was added; the solution was dissolved by vigorous stirring, and the solution was orange and transparent at this time; then the three-necked flask containing the above mixed solution was transferred to an oil bath pot for heating, and reduction was carried out at 160°C under N2 atmosphere for 3 h; after the reaction was completed, it was naturally cooled to room temperature;

[0034] (5) The solid obtained in step (3) was added to a 100 mL beaker, 20 mL of deionized water was added; 665 μL of the solution of step (4) was added, and stirring and drying were carried out at 90°C; the obtained solid powder was washed with 95% ethanol three times;

[0035] (6) 0.5 g of ruthenium chloride was dissolved in 50 mL of ultrapure water to prepare a 0.01 g·mL -1 -1 ruthenium chloride aqueous solution;

[0036] (7) The solid obtained in step (5) was added to a 100 mL beaker, 20 mL of deionized water was added; 3.1 mL of the solution of step (7) was added (at this time, the molar ratio of Pt to Ru was 0.08:1), and stirring and drying were carried out at 90°C; the obtained solid powder was washed with 95% ethanol three times, and the powder was obtained by drying at 80°C overnight;-1 ) at 5°C min -1 400°C for 1 h; i.e. the catalyst is obtained, labeled RuPt 0.08 / TP.

[0037] Example 2: The amount of nano-Pt added is 0.13:1 in molar ratio to Ru.

[0038] The conditions and steps are the same as in Example 1, but the amount of nano-Pt added in step (5) is 1 mL. It is labeled RuPt 0.13 / TP.

[0039] Example 3: The amount of nano-Pt added is 0.17:1 in molar ratio to Ru.

[0040] The conditions and steps are the same as in Example 1, but the amount of nano-Pt added in step (5) is 1.35 mL. It is labeled RuPt 0.17 / TP.

[0041] Example 4: Same as Example 3, but no Ru source is added. The sample is named Pt 0.17 / TP.

[0042] Figure 1 is a Raman picture of the catalyst prepared in Examples 1-3, Figure 2 is an X-ray diffraction (XRD) picture of the catalyst prepared in Examples 1-4; Figure 3 is an X-ray photoelectron spectroscopy (XPS) picture of different Ru catalysts prepared in Examples 1-3. From Figure 1 it can be seen that, as the amount of Pt introduced increases, there is a greater blue shift at 197 cm -1 , 637 cm -1 , 393 cm -1 and 515 cm -1 for RuPt .13 / TP than for RuPt 0.08 / TP, indicating that the interaction between the metal and the metal, the metal and the carrier gradually increases, while RuPt 0.17 / TP is comparable to the spectrum of RuPt 0.13 / TP, indicating that there is a limit to the modification of Pt particles. From Figure 2 it can be seen that no identifiable diffraction peak related to Ru nano-clusters is found in the Ru-based catalyst, and as the amount of Pt loading increases, no diffraction peak related to Pt and RuPt alloy diffraction peak is observed, indicating that Ru and Pt have good dispersion on the carrier, and the particle size is quite small. From Figure 3It can be seen that due to the interaction between Pt and Ru, and with the increase of Pt introduction amount, the electron-deficient Ru species (Ru δ+ ) increases; but there is a proper ratio between Pt and Ru, the threshold is about 0.13 (mol Pt / mol Ru ). The XPS spectra of Pt and Ru show that there is a strong electron coupling effect between Pt and Ru atoms; the change of the local environment of the metal surface atoms indicates that the electronic structure of the two metals (Ru and Pt) has changed significantly. Table 1 is the Ru 3d spectrum results of the catalysts prepared in Examples 1-3.

[0043] Table 1 Ru 3d spectrum results of different samples

[0044]

[0045] From Table 1, it can be seen that the introduction of Pt changes the electronic state of Ru, but cannot further modify Ru with the increase of Pt introduction amount.

[0046] Example 5: One-step hydroconversion of polycyclic aromatic hydrocarbons to high-energy fuel; using the catalysts of Examples 1-4, the steps are:

[0047] 2g acenaphthene and 90mL decalin were added to a 250mL high-temperature and high-pressure reaction kettle; the hydrogen pressure was 4MPa, heated to 60℃ for 0-3 hours, and the rotation speed was 600rpm.

[0048] Using the catalysts of Examples 1-4, the conversion rate, yield, and product selectivity achieved are shown in Table 1.

[0049] Table 2 Comparison of catalytic results of catalysts of Examples 1-4

[0050]

[0051] From Table 2, it can be seen that the catalytic activity of RuPt 0.13 / TP is significantly higher than that of RuPt 0.08 / TP, but the RuPt 0.17 / TP catalyst does not have a significant improvement, and the cis-isomer selectivity decreases. It shows that RuPt 0.13 / TP is the most suitable catalyst.

[0052] Comparative Example: Achieve the hydrogenation saturation catalysis of tricyclic polycyclic aromatic hydrocarbons at near room temperature of 60℃. The catalytic activity can be compared with the Ru / TP-400 catalyst in CN2024109320579 Table 3, and the catalysts are compared in terms of product selectivity and reactant conversion rate (Ru / TP-400 vs. RuPt 0.13Catalytic activity of the catalyst (hydrogenation reaction conditions: 2 g acenaphthene, 60℃, 4 MPa hydrogen, 0.4 g catalyst)

[0053] The results are: the Ru / TP-400 catalyst in Table 3 of CN2024109320579, at a hydrogenation temperature of 60℃, 3h, acenaphthene conversion rate is 98.8%, cis-product selectivity is 29%; 6h is required, acenaphthene conversion rate is 100%, cis-product selectivity is 95%.

[0054] The RuPt 0.13 / TP catalyst, at a hydrogenation temperature of 60℃, only 3h is required, acenaphthene conversion rate is 100%, cis-product selectivity is 96%. The RuPt 0.08 / TP and RuPt 0.17 The hydrogenation catalytic activity of the RuPt

[0055] Therefore, the Ru hydrogenation catalytic activity of the present application is higher than that of the hydrogenation catalyst in CN2024109320579.

[0056] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. Use of a catalyst for catalyzing the one-step hydroconversion of polycyclic aromatic hydrocarbons into high energy density fuels, characterized in that, The high energy density fuel is one or more of perhydroacenaphthylene, perhydrofluorene, decahydro naphthalene, or perhydroanthracene. The preparation method of the catalyst comprises the following steps: (1) mixing a titanium source and a structure directing agent uniformly to obtain an aging solution; the structure directing agent is acetic acid; (2) hydrothermally crystallizing the aging solution, then filtering and drying the solid; (3) calcining the solid obtained in step (2); (4) dissolving a platinum source and a base in ethylene glycol to obtain platinum nanoparticles by reduction; (5) preparing a ruthenium source into an aqueous solution; (6) adding the solid obtained in step (3) into deionized water, then adding the platinum nanoparticles in step (4), mixing uniformly at a certain temperature and drying to obtain a solid; (7) washing the solid obtained in step (6) with ethanol, then dispersing it into water, adding the aqueous solution of the ruthenium source in step (5), the molar ratio of ruthenium in the aqueous solution to platinum in the solid being 1:(0.05-0.20), mixing uniformly at a certain temperature and drying to obtain a solid, then reducing the solid in a H2 / Ar atmosphere; thus the catalyst is obtained.

2. Use according to claim 1, characterized in that, The titanium source in step (1) is tetrabutyl titanate; the volume ratio of tetrabutyl titanate to acetic acid is 1:(3-5).

3. Use according to claim 1, characterized in that, The hydrothermal crystallization condition in step (2) is 180-220℃ for 12-36h.

4. Use according to claim 1, characterized in that, The calcination temperature in step (3) is 300-500℃, and the calcination time is 2-6h.

5. The use according to claim 1, characterized in that, The platinum source in step (4) is chloroplatinic acid hexahydrate, and the base is sodium hydroxide; the reduction temperature is 140-180℃.

6. The use according to claim 1, characterized in that, The ruthenium source in step (5) is ruthenium chloride.

7. The use according to claim 1, characterized in that, The reduction temperature in step (7) is 300-500℃.

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