An organic hydrogen transfer aid for propane dehydrogenation and its synthesis method

Abstract

The present invention belongs to the field of catalyst technology, and specifically discloses an organic hydrogen transfer aid for propane dehydrogenation and a synthesis method thereof. The preparation method described in the present invention is to first coat the surface of a quinone material (L) with a layer of SiO2, and then perform a hydrothermal crystallization treatment to form an S-1 molecular sieve shell to obtain an L@S-1 material. Through the confinement of the molecular sieve pores, the quinone material can realize a hydrogenation-dehydrogenation cycle at a higher reaction temperature. When the material is used in combination with a noble metal propane dehydrogenation catalyst, a series reaction of propane dehydrogenation and hydrogenation of the quinone material is realized, the hydrogen partial pressure of the propane dehydrogenation process is reduced, and the thermodynamic equilibrium limit is broken through, thereby realizing a propane dehydrogenation reaction at a lower reaction temperature. The reduction in reaction temperature will bring about advantages such as reduced energy consumption and increased catalyst stability.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and particularly relates to an organic hydrogen transfer aid for propane dehydrogenation and a synthesis method thereof. Background Art

[0002] In recent years, driven by multiple factors, including the electrification of automobiles, the dual-carbon economy, and shale gas development, the propane dehydrogenation industry has experienced explosive growth. Currently, the propane dehydrogenation process consumes approximately 600 kg of standard coal per ton of propylene, emitting approximately 2.2 tons of carbon dioxide. Based on a 25 million ton propylene production capacity, this industry's carbon emissions exceed 50 million tons per year. Reducing reaction energy consumption is crucial to the healthy development of the industry.

[0003] Propane catalytic dehydrogenation is a volume-increasing and highly endothermic reaction. Due to thermodynamic equilibrium constraints, the reaction generally occurs at high temperatures of 550–600°C. High-temperature reactions present a series of problems: (1) Temperature increases are accompanied by high energy consumption; (2) Propane, propylene, and reaction intermediates are prone to coking and deactivation at high temperatures, reducing propylene selectivity and increasing carbon emissions, affecting process economics, increasing process difficulty, and enhancing process safety; (3) Catalysts are prone to loss and sintering at high temperatures, affecting catalyst activity and life. Therefore, achieving low-temperature propane dehydrogenation is the only way to reduce carbon emissions.

[0004] The equilibrium conversion rate of propane dehydrogenation can be expressed as k=(p C3H6▪ p H2 ) / p C3H8By designing special catalysts or reaction processes to reduce the H2 partial pressure, the propylene partial pressure increases accordingly, corresponding to a higher propylene yield. This makes it possible to achieve a significant propylene single-pass yield at a lower reaction temperature. For example, Suljo Linic et al. reported that a 140% propylene yield was achieved at 580°C over a PtSn / SiO2 catalyst by selectively permeating H2 through a SiO2 / Al2O3 membrane (Science 383(2024)1325). Gong Jinlong et al. used the reaction of lattice oxygen in FeVO4 with H2 to achieve a chemical chain dehydrogenation process at 550°C. The FeVO4 can be regenerated during the regeneration process, but the propylene yield in this process did not exceed the thermodynamic limit (Science 381(2023)886). Currently, these cutting-edge technologies face significant barriers to industrial application. Regarding membrane materials, large-scale membranes are difficult to synthesize, expensive, and have limited throughput, making it difficult to meet industrial demand. In chemical chaining dehydrogenation, the reaction of H2 with lattice oxygen can reduce the H2 partial pressure. However, the resulting H2O has serious negative effects. H2O molecules often adsorb more strongly on the catalyst surface than the feed propane, reducing the catalyst's adsorption of propane and severely affecting conversion. For example, Cr-based catalysts experience significant deactivation when exposed to 0.3% water vapor in the feed gas. Furthermore, H2O can damage the catalyst structure (for example, converting the active Lewis acid site into a Brønsted reaction and converting some of the alloy in the alloy catalyst into oxides). Consequently, low-temperature propane dehydrogenation reactions currently face significant challenges.

[0005] In response to the current problems of high propane dehydrogenation reaction temperature and large carbon emissions, the present invention aims to develop a material that can break the thermodynamic equilibrium limitation and achieve low-temperature propane dehydrogenation reaction by transferring the H2 produced in the propane dehydrogenation reaction. Summary of the Invention

[0006] To address the above technical problems, the present invention provides an organic hydrogen transfer agent for propane dehydrogenation and a synthesis method thereof. The organic hydrogen transfer material of the present invention, acting in conjunction with a propane dehydrogenation catalyst, can react in series with the H2 generated during the reaction under reaction conditions, recovering the H2 during regeneration. By transferring the H2 generated during the reaction, thermodynamic equilibrium constraints are broken, enabling low-temperature propane dehydrogenation.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] The first aspect of the present invention provides a method for synthesizing an organic hydrogen transfer agent for propane dehydrogenation, the method comprising the following steps:

[0009] (1) Dispersing quinone compounds and surfactants in an alkaline ethanol-water solution, adding TEOS for hydrolysis to obtain L@SiO2;

[0010] (2) The obtained L@SiO2 and template solution are hydrothermally crystallized together, and the organic hydrogen transfer aid L@S-1 material is obtained after filtration, washing and calcination.

[0011] Reactions of inorganic materials with H₂ pose challenges such as the generation of negatively charged H₂O, poor cyclic performance, and the need to overcome slow reaction rates caused by internal lattice oxygen transfer. Organic tandem reactions, on the other hand, are generally homogeneous reactions in the gas phase, characterized by rapid reaction rates, excellent cyclic performance, and the ability to quickly and efficiently transfer H₂. The present invention selects quinone compounds with a well-developed hydrogenation-dehydrogenation cycle (reaction process L+x / 2H₂-----HxL; regeneration process HxL+x / 4O₂------L+x / 2H₂O). Under propane dehydrogenation reaction conditions, these compounds react with some of the generated H₂ to shift the reaction equilibrium to the right, thereby lowering the propane dehydrogenation temperature. The generated hydroquinone compounds can then react with oxygen in the air during the regeneration process to return to a quinone state. Furthermore, to prevent these compounds from escaping the reaction system along with the reaction products, molecular sieves are used to encapsulate these compounds to form the L@S-1 material. Because these molecules are much larger than the pore size of the molecular sieve, they remain permanently attached to the catalyst, acting as catalyst promoters.

[0012] Furthermore, the quinone compound is at least one of naphthoquinone, anthraquinone, and phenanthrenequinone, and the mass ratio of the quinone compound to SiO2 is 1:20~1:4.

[0013] Furthermore, the quinone compound is anthraquinone.

[0014] Furthermore, the surfactant is one of polyvinyl pyrrolidone, polyvinyl alcohol, and polyethylene glycol, and the mass ratio of the quinone compound to the surfactant is 10:1 to 2:1.

[0015] Furthermore, the surfactant is polyvinyl pyrrolidone.

[0016] Furthermore, the mass ratio of ethanol to water in the ethanol-water solution is 1:1 to 5:1.

[0017] Furthermore, the template is one of tetraethylammonium hydroxide and tetrapropylammonium hydroxide, and the concentration of the template solution is 0.1-0.6 mol / L.

[0018] Furthermore, the mass ratio of the L@SiO2 to the template solution is 1:10~1:100.

[0019] Furthermore, the temperature of the hydrothermal crystallization is 160-180°C.

[0020] Furthermore, the temperature of the hydrothermal crystallization is 170°C.

[0021] A second aspect of the present invention provides an organic hydrogen transfer agent L@S-1 for propane dehydrogenation, synthesized by the aforementioned synthesis method. L is a quinone compound, and S-1 is a coated S-1 molecular sieve material. This agent, when used in conjunction with a propane dehydrogenation catalyst, promotes a rightward shift in equilibrium through the H2 generated during the transfer reaction, thereby lowering the propane dehydrogenation reaction temperature.

[0022] Preferably, the organic hydrogen transfer aid is used in a propane dehydrogenation reaction, and the organic hydrogen transfer aid is used together with a propane dehydrogenation catalyst, the propane dehydrogenation catalyst is one of a Pt catalyst and a Ru catalyst, and the mass ratio of the organic hydrogen transfer aid to the propane dehydrogenation catalyst is 0.5:1 to 5:1.

[0023] Furthermore, the propane dehydrogenation reaction temperature is 400-450°C, and the reaction space velocity is 0.1-2h -1 .

[0024] The beneficial effects of this application are as follows:

[0025] The preparation method described in the present invention involves first coating the surface of a quinone material (L) with a layer of SiO2, then subjecting it to hydrothermal crystallization to form an S-1 molecular sieve shell, resulting in an L@S-1 material. Through the confinement of the molecular sieve pores, the quinone material can undergo a hydrogenation-dehydrogenation cycle at relatively high reaction temperatures. When used in conjunction with a noble metal propane dehydrogenation catalyst, this material achieves a tandem reaction of propane dehydrogenation and hydrogenation of the quinone material, reducing the hydrogen partial pressure during the propane dehydrogenation process and breaking through thermodynamic equilibrium limitations, thereby enabling propane dehydrogenation at relatively low reaction temperatures. This reduction in reaction temperature results in reduced energy consumption and increased catalyst stability, among other advantages. This is specifically reflected in the following aspects:

[0026] (1) By connecting propane dehydrogenation and quinone compound hydrogenation in series, the equilibrium of the propane dehydrogenation reaction is promoted to the right, a higher propylene yield can be obtained at a lower reaction temperature, and the energy consumption of the process can be greatly reduced.

[0027] (2) At lower reaction temperatures, the catalyst maintains good stability and high activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Graph showing the stability changes during the synergistic catalytic cycle of propane dehydrogenation catalyst A1 and organic hydrogen transfer aid B1. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] Example 1: Preparation of organic hydrogen transfer aid B1

[0031] Dissolve 0.1g of polyvinylpyrrolidone in 25ml of 0.4mol / L ammonia solution, then add 75ml of 95% ethanol. Add 0.5g of anthraquinone and disperse under stirring for 2 hours. Then, add 7.5ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 150ml of 0.3mol / L tetrapropylammonium hydroxide solution and transferred to a hydrothermal reactor for hydrothermal crystallization at 170°C for 72 hours. After filtering and washing, the solid is calcined at 500°C for 4 hours. This is designated as organic hydrogen transfer aid B1.

[0032] Comparative Example 1: Preparation of organic hydrogen transfer aid B2

[0033] 0.1g polyvinylpyrrolidone and 0.5g anthraquinone were added to 150ml of 0.3 mol / L tetrapropylammonium hydroxide aqueous solution and dispersed with stirring for 2 hours. Then, 7.5ml of tetraethyl orthosilicate (TEOS) was added dropwise and stirred for 6 hours after the addition was complete. Hydrothermal crystallization was performed at 170°C for 72 hours. After filtration and washing, the product was calcined at 500°C for 4 hours. This product was designated as organic hydrogen transfer agent B2.

[0034] Comparative Example 2: Preparation of organic hydrogen transfer aid B3

[0035] Dissolve 0.1g of polyvinylpyrrolidone in 25ml of 0.4mol / L ammonia solution, then add 75ml of 95% ethanol. Add 0.5g of anthraquinone and disperse under stirring for 2 hours. Then, add 7.5ml of tetraethyl orthosilicate (TEOS) dropwise. Continue stirring for 3 hours after the addition is complete. After filtration and washing, calcinate at 500℃ for 4 hours. This product is designated as organic hydrogen transfer agent B3.

[0036] Comparative Example 3: Preparation of organic hydrogen transfer aid B4

[0037] Mix 75 ml of 95% ethanol with 25 ml of 0.4 mol / L ammonia solution, then add 0.5 g of anthraquinone and disperse under stirring for 2 hours. Then, add 7.5 ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 150 ml of 0.3 mol / L tetrapropylammonium hydroxide solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 170°C for 72 hours. After filtering and washing, the solid is calcined at 500°C for 4 hours. This product is designated as organic hydrogen transfer agent B4.

[0038] Example 2: Preparation of organic hydrogen transfer aid B5

[0039] Dissolve 0.05g of polyvinyl alcohol in 50ml of 0.2mol / L ammonia solution, then add 50ml of 95% ethanol. Add 0.1g of naphthoquinone and disperse under stirring for 2 hours. Then, add 7.1ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 20ml of 0.3mol / L tetraethylammonium hydroxide solution and transferred to a hydrothermal reactor for hydrothermal crystallization at 160℃ for 96 hours. After filtering and washing, the solid is calcined at 500℃ for 4 hours. This product is designated as organic hydrogen transfer agent B5.

[0040] Example 3: Preparation of organic hydrogen transfer aid B6

[0041] Dissolve 0.25g of polyethylene glycol-10000 in 50ml of 0.2mol / L ammonia solution, then add 50ml of 95% ethanol. Add 0.5g of phenanthrenequinone and disperse under stirring for 2 hours. Then, add 7.5ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 80ml of 0.6mol / L tetrapropylammonium hydroxide solution and transferred to a hydrothermal reactor for hydrothermal crystallization at 180℃ for 72 hours. After filtering and washing, the solid is calcined at 500℃ for 4 hours. This product is designated as organic hydrogen transfer agent B6.

[0042] Example 4: Preparation of organic hydrogen transfer aid B7

[0043] Dissolve 0.02g of polyvinylpyrrolidone in 20ml of 0.5mol / L ammonia solution, then add 80ml of 95% ethanol. Add 0.2g of anthraquinone and disperse under stirring for 2 hours. Then, add 6.8ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 100ml of 0.1mol / L tetrapropylammonium hydroxide solution and transferred to a hydrothermal reactor for hydrothermal crystallization at 170°C for 72 hours. After filtering and washing, the solid is calcined at 450°C for 10 hours. This product is designated as organic hydrogen transfer aid B7.

[0044] Example 5: Preparation of organic hydrogen transfer aid B8

[0045] Dissolve 0.25g of polyvinylpyrrolidone in 20ml of 0.5mol / L ammonia solution, then add 80ml of 95% ethanol. Add 0.25g of anthraquinone and 0.25g of phenanthrenequinone, and disperse under stirring for 2 hours. Then, add 7.5ml of tetraethyl orthosilicate (TEOS) dropwise, stirring for 3 hours after the addition is complete. After filtering and washing, the resulting solid is added to 100ml of 0.6mol / L tetrapropylammonium hydroxide solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 170℃ for 72 hours. After filtering and washing, the solid is calcined at 500℃ for 4 hours. This product is designated as organic hydrogen transfer agent B8.

[0046] Example 6: Preparation of Propane Dehydrogenation Catalyst A1

[0047] 0.021g of H2PtCl6·6H2O and 0.026g of Zn(AC)2·2H2O were dissolved in a mixture of 1ml of ethylenediamine and 15ml of deionized water. 13g of 25% tetrapropylammonium hydroxide was added, and 8.9ml of ethyl orthosilicate was added dropwise with stirring. Stirring was continued for 6 hours after the addition was complete. The mixture was transferred to a hydrothermal reactor and hydrothermally crystallized at 170°C for 72 hours. After filtration and washing, it was calcined at 500°C for 4 hours. The resulting material was PtZn@S-1 catalyst, designated as propane dehydrogenation catalyst A1.

[0048] Example 7: Preparation of Propane Dehydrogenation Catalyst A2

[0049] 0.020g of RuCl3·3H2O and 0.058g of Cu(NO3)2·3H2O were added to a mixture of 1ml of ethylenediamine and 15ml of deionized water. 13g of 25% tetrapropylammonium hydroxide was then added dropwise with stirring. 8.9ml of ethyl orthosilicate was added, and stirring was continued for 6 hours after the addition was complete. The mixture was transferred to a hydrothermal reactor and hydrothermally crystallized at 170°C for 72 hours. After filtration and washing, it was calcined at 500°C for 4 hours. The resulting material, RuCu@S-1 catalyst, was designated as propane dehydrogenation catalyst A2.

[0050] Test Example 1: Material Composition Analysis

[0051] Whether the quinone material can be loaded inside the molecular sieve shell is a prerequisite for whether the material has functionality. First, the B1-B8 materials obtained through different treatment processes were analyzed using an organic element analysis method. The results are shown in Table 1.

[0052] Table 1

[0053]

[0054] Note: 1. Hydrogen analysis is affected by the presence of hydroxyl groups on the support surface, resulting in a biased high result. Therefore, the mass of the corresponding quinone material is calculated based on the mass ratio of carbon. 2. Material B1* is obtained by reducing material B1 in a 10% H2-Ar mixture at 400°C for 2 hours.

[0055] This method first encapsulates a quinone material with SiO2, then hydrothermally treats it to form an S-1 molecular sieve shell, yielding the L@S-1 material. Comparison in Table 1 reveals that the quinone content in the materials obtained without prior SiO2 encapsulation (B2), without hydrothermal treatment (B3), and without surfactant (B4) is significantly lower than the specified value. In contrast, after complete encapsulation and hydrothermal treatment, the calculated value deviates closely from the specified value, achieving a quinone loading of approximately 90%. Furthermore, H2 treatment significantly increases the hydrogen content of this material (B1*), and this increase reflects the characteristics of anthraquinone hydrogenation, demonstrating the material's ability to undergo hydrogenation in the appropriate environment.

[0056] Test Example 2: Evaluation of propane dehydrogenation catalytic activity

[0057] Propane dehydrogenation catalysts A1 and A2 were mixed with the organic hydrogen transfer aid materials B1-B8 from the examples and comparative examples in specific proportions, ground, pressed, and crushed into 20-40 mesh tablets. Propane dehydrogenation performance was evaluated in an atmospheric pressure fixed-bed microreactor using 99.6% C₃H₃ feed gas. The total catalyst and aid loading was 1 g. The evaluation results for the different materials are shown in Table 2.

[0058] Table 2

[0059]

[0060]

[0061]

[0062]

[0063] The equilibrium conversion is the inherent value calculated from the thermodynamic equilibrium equation for the pure propane dehydrogenation reaction at atmospheric pressure and different reaction temperatures. Changing the reaction pressure, introducing a diluent, or altering the product concentration can disrupt the reaction equilibrium.

[0064] The results in Table 2 show that the conventional PtZn@S-1 and RuCu@S-1 catalysts exhibit high catalytic activity, but due to thermodynamic equilibrium limitations, they only achieve low yields within the temperature range of 400–450°C, with yields approximately 95% of the equilibrium value. When used in combination with the L@S-1 material, propane conversion increases significantly, with yields of some materials reaching 300–400% of the equilibrium value, due to a tandem reaction between the generated H₂ and the quinone material, which reduces the H₂ partial pressure. Therefore, this tandem reaction may enable the achievement of significant single-pass propylene yields at lower reaction temperatures, and lowering the reaction temperature can help save reaction energy. For the organic hydrogen transfer aids in comparative examples B2, B3, and B4, due to imperfect synthesis methods, the quinone material is confined within the molecular sieve shell, resulting in a less pronounced improvement.

[0065] Test Example 3: Cycling Stability of Hydrogen Transfer Materials

[0066] Another key to the material is whether the hydrogen transfer material can be stably circulated. A1-B1 combination was used, where B1:A1=5 (mass ratio), reaction temperature was 400℃, and propane space velocity was 0.1h -1 The reaction was carried out for 2 h each time, followed by N2 purge-air regeneration-N2 purge regeneration, with a regeneration temperature of 400°C and a regeneration time of 0.5 h.

[0067] Figure 1 This is a graph showing the catalytic performance changes after 200 cycles of propane dehydrogenation catalyst A1 and organic hydrogen transfer aid B1. Catalytic performance refers to a comprehensive index of propane conversion rate and propylene selectivity. If the long-term reaction fluctuation is less than 5%, the catalytic performance can be considered stable. Figure 1 It can be seen that within 200 cycles, the propane conversion rate of the organic hydrogen transfer agent B1 on the left vertical axis is 12%-13%, and the propylene selectivity on the right vertical axis is 97.5%-99%. The performance remains stable and has the characteristic of significantly improving the single-pass yield of propane dehydrogenation.

[0068] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for synthesizing an organic hydrogen transfer agent for propane dehydrogenation, characterized in that: The synthesis method comprises the following steps: (1) dispersing a quinone compound L and a surfactant in an alkaline ethanol-water solution, adding TEOS to hydrolyze to obtain L@SiO2, wherein the surfactant is one of polyvinyl pyrrolidone, polyvinyl alcohol, and polyethylene glycol; (2) The obtained L@SiO2 and template solution are hydrothermally crystallized together, and the organic hydrogen transfer aid L@S-1 material is obtained after filtration, washing and calcination.

2. The method for synthesizing an organic hydrogen transfer agent for propane dehydrogenation according to claim 1, characterized in that: The quinone compound is at least one of naphthoquinone, anthraquinone, and phenanthrenequinone, and the mass ratio of the quinone compound to SiO2 is 1:20 to 1:

4.

3. The method for synthesizing an organic hydrogen transfer aid for propane dehydrogenation according to claim 1, characterized in that: The mass ratio of the quinone compound to the surfactant is 10:1 to 2:

1.

4. The method for synthesizing an organic hydrogen transfer aid for propane dehydrogenation according to claim 1, characterized in that: The mass ratio of ethanol to water in the ethanol-water solution is 1:1 to 5:

1.

5. The method for synthesizing an organic hydrogen transfer agent for propane dehydrogenation according to claim 1, characterized in that: The template agent is one of tetraethylammonium hydroxide and tetrapropylammonium hydroxide, and the concentration of the template agent solution is 0.1-0.6 mol / L.

6. The method for synthesizing an organic hydrogen transfer aid for propane dehydrogenation according to claim 1, characterized in that: The mass ratio of the L@SiO2 to the template solution is 1:10~1:

100.

7. The method for synthesizing an organic hydrogen transfer agent for propane dehydrogenation according to claim 1, characterized in that: The temperature of the hydrothermal crystallization is 160-180°C.

8. An organic hydrogen transfer aid for propane dehydrogenation synthesized by the synthesis method according to any one of claims 1 to 7.

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