Homogeneous organic metal catalyst for cracking hydrocarbon fuel RX-2 as well as preparation method and application of homogeneous organic metal catalyst

Abstract

The invention discloses a homogeneous organic metal catalyst for cracking hydrocarbon fuel RX-2 as well as a preparation method and application of the homogeneous organic metal catalyst, and the homogeneous organic metal catalyst which is used for cracking RX-2 and has better dissolving performance and lower additive amount is prepared on the basis of a liquid phase reaction method with a simple process by regulating and controlling a metal active center of the catalyst and the types of ligands. The prepared homogeneous organic metal catalyst is applied to RX-2 cracking, the fuel cracking conversion rate and the gas production rate are effectively improved, the content of effective gas is increased, and the heat absorption performance of fuel is improved. The method has good practical application value in the aspect of active cooling in the hypersonic field.

Description

Technical Field

[0001] This invention belongs to the field of catalyst research and application technology, and relates to the design, preparation and application of homogeneous organometallic catalysts for the cracking of endothermic hydrocarbon fuel RX-2. Background Technology

[0002] High-speed flight (Mach number Ma≥5) technology, as a cutting-edge technology in the aerospace field, represents the development level of a nation's weaponry and is a frontier technology vigorously developed by major military powers. During high-speed flight, the aerodynamic heat generated by friction causes aircraft to face a severe "thermal barrier" problem. Endothermic hydrocarbon fuels, serving as both a power and cooling source for aircraft, can solve the bottleneck problems of the "thermal barrier" and insufficient thrust encountered during high-speed flight.

[0003] RX-2 is an existing liquid endothermic hydrocarbon fuel that already meets the requirements for Mach 5 high-speed flight. However, with the development of ultra-high speed, long endurance, and reusable high-speed aircraft, endothermic fuels are required to have higher heat sink properties and better anti-coking performance. Currently, the heat sink and anti-coking properties of RX-2 fuel do not yet meet such stringent performance requirements, and its reactivity needs further improvement.

[0004] Catalytic cracking, by regulating the fuel cracking reaction pathway and controlling product distribution, can effectively improve fuel heat sinking and, to some extent, inhibit fuel coking, making it one of the effective technical approaches to comprehensively improve fuel cracking performance. The key to endothermic hydrocarbon fuel catalytic cracking lies in the development of highly active and stable catalysts. Existing heterogeneous packed catalysts have small contact areas and high heat and mass transfer resistance; heterogeneous coated catalysts have cumbersome coating processes and are prone to coating collapse at high temperatures; and pseudo-homogeneous nanocatalysts have complex synthesis processes and nanoparticles are prone to agglomeration and sedimentation. In short, existing heterogeneous catalysts generally suffer from insufficient catalytic efficiency, making them difficult to implement in engineering applications.

[0005] Homogeneous organometallic catalysts require no immobilization or spraying and can effectively increase catalyst utilization and reaction rates without significantly altering the fundamental physical properties of fuels; however, related research is limited. The paper "Synthesis of Bifunctional Organometallic Complexes and Their Application in Fuel Cracking" developed a bifunctional additive for fuel catalytic cracking, but only studied one ligand, 2,2,6,6-tetramethyl-3,5-heptadecane. The synthesis process was relatively complex, and a catalyst addition of at least 300 ppm was required for good reaction performance. Therefore, further research is needed to develop organic compounds with different functional groups, better solubility, and lower addition amounts for hydrocarbon fuel catalytic cracking using simplified preparation processes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a homogeneous organometallic catalyst for the cracking of hydrocarbon fuel RX-2, its preparation method, and its application. This addresses the issues of the inadequacy of the heat sink and anti-coking properties of currently used endothermic hydrocarbon fuel RX-2 to meet the development requirements of higher speeds, longer endurance, and reusable high-speed aircraft, as well as its low cracking conversion rate and poor reaction selectivity during thermal cracking. The present invention improves the endothermic performance of hydrocarbon fuels based on homogeneous organometallic catalysts, preparing a series of homogeneous organometallic catalysts. Without affecting the basic physicochemical properties of the fuel, it can effectively control product distribution, improve fuel cracking rate and gas production rate, thereby enhancing its endothermic capacity and anti-coking performance.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A homogeneous organometallic catalyst for cracking hydrocarbon fuel RX-2. This catalyst is composed of a metal active center and an organic ligand. The metal active centers include one or more of Ni, Fe, Pd, Ru, and Rh; The organic ligands include one or more of triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl, and pyridine.

[0008] The present invention also includes the following technical features: Specifically, the catalyst includes one or more of the following: bis(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)nickel dichloride, tri(triphenylphosphine)rhodium dichloride, bis(tri-tert-butylphosphine)palladium, [1,1'-bis(diphenylphosphine)ferrocene]nickel dichloride, [1,1'-bis(diisopropylphosphine)ferrocene]palladium dichloride, dichlorobis(4-methylisopropylphenyl)ruthenium, and tris(2,2'-bipyridine)ruthenium dichloride.

[0009] A method for preparing a homogeneous organometallic catalyst for cracking hydrocarbon fuel RX-2 includes the following steps: s1, Add solvent to metal salt and stir continuously until metal salt is completely dissolved to obtain metal salt solution A; s2, the ligand is completely dissolved in the solvent by continuous stirring in a constant temperature water bath to obtain solution B; s3, Mix solution A and solution B, and stir thoroughly to allow them to react completely and produce a large amount of precipitate; S4, continue to add solvent to completely precipitate, and obtain the final catalyst by suction filtration and vacuum drying.

[0010] Specifically, the metal in the metal salt is selected from one or more of Ni, Fe, Pd, Ru, and Rh.

[0011] Specifically, the ligand is one or more of triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl, and pyridine.

[0012] Specifically, the solvent includes one or more of ethanol, methanol, diethyl ether, acetonitrile, and acetone.

[0013] Specifically, the catalysts prepared include one or more of the following: bis(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)nickel dichloride, tri(triphenylphosphine)rhodium dichloride, bis(tri-tert-butylphosphine)palladium, [1,1'-bis(diphenylphosphine)ferrocene]nickel dichloride, [1,1'-bis(diisopropylphosphine)ferrocene]palladium dichloride, dichlorobis(4-methylisopropylphenyl)ruthenium, and tris(2,2'-bipyridine)ruthenium dichloride.

[0014] The homogeneous organometallic catalyst for RX-2 hydrocarbon fuel cracking is used for the catalytic cracking of endothermic RX-2 hydrocarbon fuel, and the amount of homogeneous organometallic catalyst added is 20-2000 ppm.

[0015] Specifically, the homogeneous organometallic catalyst for RX-2 hydrocarbon fuel cracking is used in the catalytic cracking of endothermic RX-2 hydrocarbon fuel. In the catalytic cracking reaction of endothermic RX-2 hydrocarbon fuel, the feed rate of the mixed fuel after adding the catalyst is 3-150 mL / min, the cracking pressure is 0.1-9 MPa, and the reaction temperature is 450-850 °C. o C.

[0016] Compared with the prior art, the present invention has the following technical effects: This invention utilizes the catalytic effect of the metal active centers and the pyrolysis-initiating effect of the organic ligands in a homogeneous organometallic catalyst to effectively regulate product distribution, improve fuel pyrolysis rate and gas production rate, thereby enhancing the fuel's endothermic capacity and anti-coking performance. By controlling the types of metal active centers and organic ligands in the catalyst, a homogeneous organometallic catalyst with better solubility in fuel RX-2 without affecting the fuel's basic physicochemical properties was designed and prepared. Compared with existing research, the catalyst production process of this invention is simple, and significant improvements in fuel pyrolysis performance can be achieved at lower addition levels (below 100 ppm), which holds promise for engineering applications. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a supercritical endothermic hydrocarbon fuel pyrolysis performance evaluation device.

[0018] Figure 2 The cracking rate and gas production rate are those of Examples 1-8 and the comparative examples.

[0019] Figure 3The distribution of gaseous products in Examples 1-8 and the comparative examples is shown. Detailed Implementation

[0020] This invention provides a homogeneous organometallic catalyst for hydrocarbon fuel RX-2 cracking, its preparation method, and its application. By controlling the active metal center and the type of ligands, transition metals with excellent C-C and CH bond activation and breaking functions are preferred. Phosphine and nitrogen ligands with high stability and electronic control effects are selected. The "microenvironment" of the active metal center is changed by modifying the electron cloud density of the R group. Homogeneous organometallic catalysts with good solubility and low addition amount are designed and prepared for hydrocarbon fuel catalytic cracking, laying the foundation for subsequent engineering applications of fuel catalytic cracking.

[0021] The catalyst of this invention is a homogeneous organometallic catalyst, composed of a metal active center and an organic ligand, and is prepared by a conventional liquid-phase reaction method.

[0022] Among them, the metal active center is one or a combination of two or more of Ni, Fe, Pd, Ru and Rh.

[0023] The organic ligand is one or a combination of two or more of the following: triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl, and pyridine.

[0024] The preparation method specifically includes the following steps: (1) Add solvent to metal salt and stir continuously until metal salt is completely dissolved to obtain metal salt solution A; the metal in the metal salt is selected from one or more of Ni, Fe, Pd, Ru and Rh. (2) The ligand is completely dissolved in the solvent by constant stirring in a constant temperature water bath to obtain solution B; the ligand is one or a combination of two or more of the following: triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl and pyridine. (3) Mix solution A with solution B and stir thoroughly to allow them to react completely and produce a large amount of precipitate; (4) Continue to add some solvent to completely precipitate, and then filter and dry under vacuum to obtain the final catalyst.

[0025] The solvents used include one or more of the following: ethanol, methanol, diethyl ether, acetonitrile, acetone, etc.

[0026] The homogeneous organometallic catalysts prepared for the cracking of hydrocarbon fuel RX-2 include one or more of the following: bis(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)nickel dichloride, tri(triphenylphosphine)rhodium dichloride, bis(tri-tert-butylphosphine)palladium, [1,1'-bis(diphenylphosphine)ferrocene]nickel dichloride, [1,1'-bis(diisopropylphosphine)ferrocene]palladium dichloride, dichlorobis(4-methylisopropylphenyl)ruthenium, and tris(2,2'-bipyridine)ruthenium dichloride.

[0027] The prepared homogeneous organometallic catalyst for the cracking of hydrocarbon fuel RX-2 is used for the catalytic cracking of endothermic hydrocarbon fuel RX-2. The amount of the homogeneous organometallic catalyst added is 20-2000 ppm, preferably 40-100 ppm.

[0028] In the catalytic cracking reaction of the endothermic hydrocarbon fuel RX-2, the feed rate of the mixed fuel after adding the catalyst is 3-150 mL / min, preferably 4.5-20 mL / min. The cracking pressure is 0.1-9 MPa, preferably 3.5-6 MPa. The reaction temperature is 450-850 °C. o C, preferably 550-780 o C.

[0029] To simulate the actual operating conditions of hypersonic vehicles, the supercritical endothermic hydrocarbon fuel pyrolysis performance evaluation device designed and established in this invention is as follows: Figure 1 As shown, it mainly consists of four parts: a feeding system, a preheating system, a pyrolysis reaction system, and a product separation and collection system. It can meet the experimental requirements for feeding, reaction, and product separation and collection of fuel pyrolysis reaction under high temperature and high pressure conditions.

[0030] Fuel with a homogeneous organometallic catalyst is pumped at a constant flow rate to a preheating furnace via a high-pressure metering pump. After preheating, it enters a tubular pyrolysis reactor, which is a 3 mm × 0.5 mm 304 stainless steel tube with a 900 mm long heating reaction zone. The fuel undergoes catalytic pyrolysis at a set pyrolysis temperature. The reacted material is condensed by a cooling coil and filtered before entering a gas-liquid separator for separation. The volume of the pyrolysis gaseous products is measured by a wet flow meter, collected using a gas bag, and analyzed by gas chromatography. A back pressure valve is installed after the condenser, and N2 is introduced to regulate the pressure within the tubular reaction tube. The system pressure is fed back via pressure gauges before and after the reactor. This device can collect key experimental data including pyrolysis temperature and pressure, feed rate, pyrolysis liquid mass, and gas production. The pyrolysis performance of the fuel, such as the pyrolysis rate and gas production rate, can be quantitatively analyzed based on the obtained products.

[0031] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0032] Example 1: This embodiment provides a homogeneous organometallic catalyst for RX-2 hydrocarbon fuel cracking, its preparation method, and its application. The metal active center and organic ligand of the homogeneous organometallic catalyst are selected as Pd and triphenylphosphine, respectively. The homogeneous organometallic catalyst is prepared using a conventional liquid-phase reaction method. The specific preparation steps are as follows: (1) Add acetonitrile to palladium chloride and stir continuously until palladium chloride is completely dissolved to obtain metal salt solution A; (2) Dissolve triphenylphosphine completely in ethanol by stirring continuously in a constant temperature water bath to obtain solution B; (3) Mix metal salt solution A with ligand solution B and stir thoroughly to allow the reaction to proceed completely until a large amount of precipitate is produced; (4) Continue to add some solvent to completely precipitate, and then filter and dry under vacuum to obtain the final catalyst.

[0033] The prepared bis(triphenylphosphine)palladium dichloride was used as a catalyst and added to hydrocarbon fuel RX-2 at a concentration of 40 ppm. The RX-2 after adding bis(triphenylphosphine)palladium dichloride was thoroughly stirred and sonicated to ensure complete dissolution of the catalyst in the fuel. The RX-2 with added catalyst was then pumped at a rate of 4.5 mL / min using a horizontal flow pump. -1 The feed rate is introduced into the reactor, first passing through a material at a set temperature of 300°C. o Preheating is performed in the preheating furnace of C, and then the temperature is set to 700. o The pyrolysis reaction was carried out in reactor C. The pressure of the entire reaction system was controlled at 3.5 MPa by adjusting the back pressure valve. After the fuel filled the entire reaction system and stabilized, the catalytic pyrolysis performance was evaluated. Changes in system pressure due to hydrocarbon fuel coking were accounted for, ensuring the pyrolysis reaction proceeded for at least 15 minutes. Gas and liquid products were sampled and measured, and the amounts of gas and liquid phase products were recorded. The fuel pyrolysis rate, gas production rate, and product selectivity under the corresponding operating conditions were calculated. The RX-2 catalytic pyrolysis reaction performance is summarized in [the table / section]. Figure 2 .

[0034] Comparative example: Example 1 was repeated, with the same experimental conditions and operating parameters as in Example 1. The difference was that a homogeneous organometallic catalyst was not added, and hydrocarbon fuel RX-2 was directly used as feedstock for cracking. The reaction performance is summarized in... Figure 2 and Figure 3 .

[0035] Example 2: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst designed and prepared was bis(triphenylphosphine) nickel dichloride, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in [the relevant section]. Figure 2 and Figure 3 .

[0036] Example 3: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst designed and prepared was rhodium tris(triphenylphosphine)chloride, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in [the relevant section]. Figure 2 and Figure 3 .

[0037] Example 4: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst designed and prepared was bis(tri-tert-butylphosphine)palladium, and the preparation method was the same as in Example 1, with an addition amount of 100 ppm. Its reaction performance is also summarized in [the table below]. Figure 2 and Figure 3 .

[0038] Example 5: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst selected was [1,1'-bis(diphenylphosphine)ferrocene]nickel dichloride, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in […]. Figure 2 and Figure 3 .

[0039] Example 6: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst selected was [1,1'-bis(diisopropylphosphine)ferrocene]palladium dichloride, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in […]. Figure 2 and Figure 3 .

[0040] Example 7: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst selected was ruthenium dichlorobis(4-methylisopropylphenyl)chlorodichloro, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in [the relevant section]. Figure 2 and Figure 3 .

[0041] Example 8: Example 1 was repeated, with the experimental conditions and operating parameters identical to those in Example 1. The difference was that the homogeneous organometallic catalyst selected was ruthenium tris(2,2'-bipyridine)dichloride, and the preparation method was the same as in Example 1. Its reaction performance is also summarized in [the relevant section]. Figure 2 and Figure 3 .

[0042] according to Figure 2 The cracking rate and gas production results show that, compared with the standalone thermal cracking of hydrocarbon fuel RX-2, the cracking performance of RX-2 in Examples 1-8 with the addition of homogeneous organometallic catalysts was significantly improved, with the highest increase in cracking rate and gas production rate exceeding 10%. Among them, the highest cracking rate (41.46%) was achieved with 100 ppm of bis(tri-tert-butylphosphine)palladium catalyst, and the highest gas production rate (15.38 mmol·g⁻¹) was achieved with 40 ppm of bis(triphenylphosphine)nickel dichloride catalyst. -1 ).Depend on Figure 3 It is evident that without the addition of a homogeneous organometallic catalyst, the comparative sample exhibits the lowest levels of H2 and olefins, and the highest level of alkanes. After the addition of the catalyst, the alkane content shows a decreasing trend, indicating the generation of more H2 and olefins in the cracked gas.

[0043] Combination Figure 2 and Figure 3 The results showed that after adding a homogeneous organometallic catalyst, the cracking rate and gas production rate of hydrocarbon fuel RX-2 increased, and more H2 and olefins were obtained from the gas phase products. This indicates that the homogeneous organometallic catalyst effectively regulated the product distribution of RX-2, improving its endothermic capacity and anti-coking performance. Therefore, the method proposed in this invention for improving the endothermic performance of hydrocarbon fuels based on homogeneous organometallic catalysts is effective. The homogeneous organometallic catalyst and hydrocarbon fuel are miscible, the addition amount is low, and it does not affect the basic physicochemical properties of the fuel, showing good application prospects.

[0044] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0045] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0046] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A homogeneous organometallic catalyst for the RX-2 cleavage of hydrocarbon fuels, characterized in that, The catalyst is a homogeneous organometallic catalyst, which is composed of a metal active center and an organic ligand; The metal active center comprises one or more of Ni, Fe, Pd, Ru and Rh; The organic ligand comprises one or more of triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl and pyridine.

2. The homogeneous organometallic catalyst for the RX-2 cleavage of hydrocarbon fuels according to claim 1, wherein, The catalyst comprises one or more of bis(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)nickel dichloride, tris(triphenylphosphine)rhodium chloride, bis(tri-tert-butylphosphine)palladium, [1,1'-bis(diphenylphosphino)ferrocene]nickel dichloride, [1,1'-bis(diisopropylphosphino)ferrocene]palladium dichloride, dichlorobis(4-methylisopropylphenyl)ruthenium and tris(2,2'-bipyridine)ruthenium dichloride.

3. A method for producing a homogeneous organometallic catalyst for the RX-2 cracking of hydrocarbon fuels according to claim 1 or 2, characterized in that, The method comprises the following steps: s1, adding a solvent to a metal salt and continuously stirring until the metal salt is completely dissolved to prepare a metal salt solution A; s2, continuously stirring to completely dissolve the ligand in the solvent in a constant temperature water bath to prepare solution B; s3, mixing solution A and solution B and fully stirring to completely react to produce a large amount of precipitate; s4, continuously adding a solvent to completely precipitate, and preparing a final catalyst by suction filtration and vacuum drying.

4. The method for preparing a homogeneous organometallic catalyst for the RX-2 cracking of hydrocarbon fuels according to claim 3, characterized by, The metal in the metal salt is selected from one or more of Ni, Fe, Pd, Ru and Rh.

5. The method for preparing a homogeneous organometallic catalyst for cracking hydrocarbon fuel RX-2 as described in claim 3, characterized in that, The ligand is one or more of triphenylphosphine, tri-tert-butylphosphine, diphenylphosphine, diisopropylphosphine, 4-methylisopropylphenyl and pyridine.

6. The method for preparing the homogeneous organometallic catalyst for cracking hydrocarbon fuel RX-2 as described in claim 3, characterized in that, The solvent comprises one or more of ethanol, methanol, diethyl ether, acetonitrile and acetone.

7. The method for preparing a homogeneous organometallic catalyst for cracking hydrocarbon fuel RX-2 as described in claim 3, characterized in that, The prepared catalyst comprises one or more of bis(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)nickel dichloride, tris(triphenylphosphine)rhodium chloride, bis(tri-tert-butylphosphine)palladium, [1,1'-bis(diphenylphosphino)ferrocene]nickel dichloride, [1,1'-bis(diisopropylphosphino)ferrocene]palladium dichloride, dichlorobis(4-methylisopropylphenyl)ruthenium and tris(2,2'-bipyridine)ruthenium dichloride.

8. Use of the homogeneous organometallic catalyst for RX-2 cracking of hydrocarbon fuel according to claim 1 or 2 for endothermic RX-2 catalytic cracking of hydrocarbon fuel, wherein the addition amount of the homogeneous organometallic catalyst is 20-2000 ppm.

9. Use of a homogeneous organometallic catalyst for the thermal RX-2 cracking of a hydrocarbon fuel according to claim 8, characterized in that, In the endothermic catalytic cracking reaction of RX-2 hydrocarbon fuel, the mixed fuel feed speed after adding the catalyst is 3-150 mL / min, the cracking pressure is 0.1-9 MPa, the reaction temperature is 450-850 o C.

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