Organic hydrogen transfer auxiliary agent for propane dehydrogenation and synthesis method thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly discloses an organic hydrogen transfer additive for propane dehydrogenation and a synthesis method thereof. According to the preparation method, the surface of a quinone material (L) is coated with a layer of SiO2, then hydrothermal crystallization treatment is carried out to form an S-1 molecular sieve shell layer, an L (at) S-1 material is obtained, and hydrogenation-dehydrogenation circulation of the quinone material can be realized at a relatively high reaction temperature through limitation of molecular sieve pore channels. When the material is combined with a noble metal propane dehydrogenation catalyst for use, the cascade reaction of propane dehydrogenation and quinone material hydrogenation is realized, the hydrogen partial pressure in the propane dehydrogenation process is reduced, and the thermodynamic equilibrium limitation is broken through, so that the propane dehydrogenation reaction at lower reaction temperature is realized. The reduction of the reaction temperature can reduce the energy consumption, and the stability of the catalyst is improved.

Description

Technical Field

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

[0002] In recent years, driven by multiple factors such as the electrification of automotive energy, the dual-carbon economy, and shale gas development, the propane dehydrogenation industry has shown an explosive development trend. Currently, the energy consumption per ton of propylene in the propane dehydrogenation process is about 600 kg of standard coal, and the carbon emission is about 2.2 tons. Calculated based on a propylene production capacity of 25 million tons, the carbon emission of this industry exceeds 50 million tons / year. How to reduce the reaction energy consumption is a key issue related to the healthy development of the industry.

[0003] Propane catalytic dehydrogenation is a reaction with an increase in volume and a strong endothermic nature. Affected by the thermodynamic equilibrium limit, the reaction generally occurs under high-temperature conditions of 550 - 600 °C. The high-temperature reaction brings a series of problems: (1) The increase in temperature is accompanied by relatively high energy consumption; (2) Propane, propylene, and reaction intermediates are prone to coking and deactivation at high temperatures, reducing the propylene selectivity, increasing the carbon emission, affecting the economy of the process, and increasing the process difficulty and process safety; (3) The catalyst is prone to loss and sintering at high temperatures, affecting the catalyst activity and service life. Therefore, realizing low-temperature propane dehydrogenation reaction is the only way to reduce carbon emissions.

[0004] The propane dehydrogenation equilibrium conversion rate can be expressed as k=(p C3H6▪ p H2 ) / p C3H8, when designing special catalysts or reaction processes to reduce the partial pressure of H2, the partial pressure of propylene rises correspondingly, corresponding to a higher propylene yield. In this way, it is possible to obtain a considerable single-pass propylene yield at a lower reaction temperature. For example, as reported by Suljo Linic et al., a 140% propylene yield was achieved at 580 °C on a PtSn / SiO2 catalyst through the selective permeation of H2 by an SiO2 / Al2O3 membrane material (Science 383(2024)1325). Gong Jinlong et al. used the lattice oxygen in FeVO4 to react with H2 to achieve the chemical looping dehydrogenation process at 550 °C. This FeVO4 can be regenerated during the regeneration process, but the propylene yield in this process did not break through the thermodynamic limit (Science 381(2023) 886). Currently, there are still significant barriers to the industrial application of these cutting-edge technologies. In terms of membrane materials, on the one hand, the synthesis of large-scale membranes is difficult, expensive, and the throughput is limited, making it difficult to meet industrial requirements; in terms of chemical looping dehydrogenation, the partial pressure of H2 can be reduced by the reaction of H2 with lattice oxygen. However, the generated H2O brings serious negative effects. On the one hand, the adsorption of H2O molecules on the catalyst surface is often stronger than that of the raw material propane, reducing the adsorption of the catalyst on propane and thus seriously affecting the conversion rate. For example, when there is 0.3% water vapor in the raw material gas, the Cr-based catalyst is significantly deactivated. On the other hand, H2O may damage the catalyst structure (such as converting the active center Lewis acid into Brønsted, and converting some alloys in the alloy catalyst into oxides). Therefore, there are still great difficulties in the current low-temperature propane dehydrogenation reaction.

[0005] In view of the problems of high reaction temperature and large carbon emissions in the current propane dehydrogenation reaction, developing a material that can transfer the H2 generated in the propane dehydrogenation reaction to break the thermodynamic equilibrium limit and thus achieve low-temperature propane dehydrogenation reaction is the technical problem to be solved by the present invention. Summary of the Invention

[0006] To solve the above technical problems, the purpose of the present invention is to provide an organic hydrogen transfer assistant for propane dehydrogenation and its synthesis method. The organic hydrogen transfer material of the present invention acts together with the propane dehydrogenation catalyst, can undergo a tandem reaction with the H2 generated in the reaction under the reaction conditions, and is restored during the regeneration process. By transferring the H2 generated in the reaction, the thermodynamic equilibrium limit is broken, and low-temperature propane dehydrogenation reaction is achieved.

[0007] The purpose of the present invention can be achieved by the following technical solutions: In the first aspect of the present invention, a synthesis method of an organic hydrogen transfer assistant for propane dehydrogenation is provided. The synthesis method includes the following steps: (1) Disperse quinone compounds and surfactants in an alkaline ethanol-aqueous solution, and add TEOS for hydrolysis to obtain L@SiO2; (2) Hydrothermally crystallize the obtained L@SiO2 and the template agent solution, and obtain the organic hydrogen transfer promoter L@S-1 material through filtration, washing, and calcination.

[0008] There are problems in the reaction of inorganic materials with H2, such as the easy formation of H2O with negative effects, poor cycling performance, and the need to overcome the slow reaction rate caused by the internal transfer of lattice oxygen; while organic tandem reactions are generally homogeneous reactions in the gas phase, with fast reaction rates and good cycling performance, and have the ability to transfer H2 quickly and efficiently. In the present invention, quinone compounds with good hydrogenation-dehydrogenation cycles are selected (reaction process L + x / 2H2 ----- HxL; regeneration process HxL + x / 4O2 ------ L + x / 2H2O). Such compounds can react with a part of the generated H2 under the conditions of propane dehydrogenation reaction to promote the right shift of the reaction equilibrium, thereby reducing the temperature of the propane dehydrogenation reaction; the generated hydroquinone compounds can react with oxygen in the air during the regeneration process to return to the quinone state. At the same time, in order to prevent such compounds from flowing out of the reaction system together with the reaction products, molecular sieves are used to encapsulate such compounds to form L@S-1 materials. Since the size of such molecules is much larger than the pore diameter of the molecular sieve, they can stay with the catalyst for a long time and play the role of catalyst additives.

[0009] Further, the quinone compound is at least one of naphthoquinone, anthraquinone, and phenanthraquinone, and the mass ratio of the quinone compound to SiO2 is 1:20 to 1:4.

[0010] Still further, the quinone compound is anthraquinone.

[0011] Further, the surfactant is one of polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol, and the mass ratio of the quinone compound to the surfactant is 10:1 to 2:1.

[0012] Still further, the surfactant is polyvinylpyrrolidone.

[0013] Further, the mass ratio of ethanol to water in the ethanol-aqueous solution is 1:1 to 5:1.

[0014] Further, the template agent is one of tetraethylammonium hydroxide and tetrapropylammonium hydroxide, and the concentration of the template agent solution is 0.1 to 0.6 mol / L.

[0015] Further, the mass ratio of L@SiO2 to the template agent solution is 1:10 to 1:100.

[0016] Further, the temperature of the hydrothermal crystallization is 160 to 180 °C.

[0017] Still further, the temperature of the hydrothermal crystallization is 170 °C.

[0018] The second aspect of the present invention provides an organic hydrogen transfer promoter L@S-1 for propane dehydrogenation obtained by the above synthesis method. Wherein L is a quinone compound, and S-1 is a coated S-1 molecular sieve material. This promoter material is used together with a propane dehydrogenation catalyst to promote the right shift of the equilibrium through the H2 generated in the transfer reaction and reduce the propane dehydrogenation reaction temperature.

[0019] Preferably, the organic hydrogen transfer promoter is applied to the propane dehydrogenation reaction and used together with a propane dehydrogenation catalyst. The propane dehydrogenation catalyst is one of Pt and Ru catalysts, and the mass ratio of the organic hydrogen transfer promoter to the propane dehydrogenation catalyst is 0.5:1 to 5:1.

[0020] Furthermore, the temperature of the propane dehydrogenation reaction is 400 - 450 °C, and the reaction space velocity is 0.1 - 2 h -1 .

[0021] The beneficial effects that this application can produce are as follows: The preparation method of the present invention is to first coat a layer of SiO2 on the surface of the quinone material (L), and then perform hydrothermal crystallization treatment to form an S-1 molecular sieve shell layer, obtaining an L@S-1 material. Through the confinement of the molecular sieve pores, the quinone material can achieve a hydrogenation-dehydrogenation cycle at a relatively high reaction temperature. When this material is used in combination with a noble metal propane dehydrogenation catalyst, a tandem reaction of propane dehydrogenation and quinone material hydrogenation is realized, reducing the hydrogen partial pressure in the propane dehydrogenation process and breaking through the thermodynamic equilibrium limitation, thereby realizing propane dehydrogenation reaction at a lower reaction temperature. The reduction of the reaction temperature will bring advantages such as reduced energy consumption and increased catalyst stability. Specifically reflected in: (1) Through the tandem of propane dehydrogenation and quinone compound hydrogenation, the right shift of the propane dehydrogenation reaction equilibrium is promoted, and a higher propylene yield can be obtained at a lower reaction temperature, greatly reducing the process energy consumption.

[0022] (2) At a lower reaction temperature, the catalyst maintains good stability and high activity. Description of the Drawings

[0023] Figure 1 Variation diagram of the co-catalytic cycle stability of propane dehydrogenation catalyst A1 and organic hydrogen transfer promoter B1. Detailed Embodiments

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0025] Example 1: Preparation of Organic Hydrogen Transfer Auxiliary B1 Dissolve 0.1 g of polyvinylpyrrolidone in 25 ml of 0.4 mol / L aqueous ammonia solution, and then add 75 ml of 95% ethanol. Add 0.5 g of anthraquinone and disperse it with stirring for 2 h. Then dropwise add 7.5 ml of tetraethyl orthosilicate (TEOS), and continue stirring for 3 h after the addition is complete. After filtration and washing, the obtained solid is added to 150 ml of 0.3 mol / L aqueous solution of tetrapropylammonium hydroxide, transferred to a hydrothermal autoclave, and hydrothermally crystallized at 170 °C for 72 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer auxiliary B1.

[0026] Comparative Example 1: Preparation of Organic Hydrogen Transfer Auxiliary B2 Add 0.1 g of polyvinylpyrrolidone and 0.5 g of anthraquinone to 150 ml of 0.3 mol / L aqueous solution of tetrapropylammonium hydroxide, and disperse it with stirring for 2 h. Then dropwise add 7.5 ml of tetraethyl orthosilicate (TEOS), and continue stirring for 6 h after the addition is complete. Hydrothermally crystallize at 170 °C for 72 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer auxiliary B2.

[0027] Comparative Example 2: Preparation of Organic Hydrogen Transfer Auxiliary B3 Dissolve 0.1 g of polyvinylpyrrolidone in 25 ml of 0.4 mol / L aqueous ammonia solution, and then add 75 ml of 95% ethanol. Add 0.5 g of anthraquinone and disperse it with stirring for 2 h. Then dropwise add 7.5 ml of tetraethyl orthosilicate (TEOS), and continue stirring for 3 h after the addition is complete. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer auxiliary B3.

[0028] Comparative Example 3: Preparation of Organic Hydrogen Transfer Auxiliary B4 Mix 75 ml of 95% ethanol with 25 ml of 0.4 mol / L aqueous ammonia solution, then add 0.5 g of anthraquinone and disperse it with stirring for 2 h. Then dropwise add 7.5 ml of tetraethyl orthosilicate (TEOS), and continue stirring for 3 h after the addition is complete. After filtration and washing, the obtained solid is added to 150 ml of 0.3 mol / L aqueous solution of tetrapropylammonium hydroxide, transferred to a hydrothermal autoclave, and hydrothermally crystallized at 170 °C for 72 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer auxiliary B4.

[0029] Example 2: Preparation of Organic Hydrogen Transfer Auxiliary B5 Dissolve 0.05 g of polyvinyl alcohol in 50 ml of 0.2 mol / L ammonia water solution, and then add 50 ml of 95% ethanol. Add 0.1 g of naphthoquinone and disperse it under stirring for 2 h. Then add 7.1 ml of tetraethyl orthosilicate (TEOS) dropwise, and continue stirring for 3 h after the addition. After filtration and washing, the obtained solid is added to 20 ml of 0.3 mol / L tetraethylammonium hydroxide aqueous solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 160 °C for 96 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer promoter B5.

[0030] Example 3: Preparation of organic hydrogen transfer promoter B6 Dissolve 0.25 g of polyethylene glycol-10000 in 50 ml of 0.2 mol / L ammonia water solution, and then add 50 ml of 95% ethanol. Add 0.5 g of phenanthraquinone and disperse it under stirring for 2 h. Then add 7.5 ml of tetraethyl orthosilicate (TEOS) dropwise, and continue stirring for 3 h after the addition. After filtration and washing, the obtained solid is added to 80 ml of 0.6 mol / L tetrapropylammonium hydroxide aqueous solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 180 °C for 72 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer promoter B6.

[0031] Example 4: Preparation of organic hydrogen transfer promoter B7 Dissolve 0.02 g of polyvinylpyrrolidone in 20 ml of 0.5 mol / L ammonia water solution, and then add 80 ml of 95% ethanol. Add 0.2 g of anthraquinone and disperse it under stirring for 2 h. Then add 6.8 ml of tetraethyl orthosilicate (TEOS) dropwise, and continue stirring for 3 h after the addition. After filtration and washing, the obtained solid is added to 100 ml of 0.1 mol / L tetrapropylammonium hydroxide aqueous solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 170 °C for 72 h. After filtration and washing, it is calcined at 450 °C for 10 h, denoted as organic hydrogen transfer promoter B7.

[0032] Example 5: Preparation of organic hydrogen transfer promoter B8 Dissolve 0.25 g of polyvinylpyrrolidone in 20 ml of 0.5 mol / L ammonia water solution, and then add 80 ml of 95% ethanol. Add 0.25 g of anthraquinone and 0.25 g of phenanthraquinone, and disperse it under stirring for 2 h. Then add 7.5 ml of tetraethyl orthosilicate (TEOS) dropwise, and continue stirring for 3 h after the addition. After filtration and washing, the obtained solid is added to 100 ml of 0.6 mol / L tetrapropylammonium hydroxide aqueous solution, transferred to a hydrothermal reactor, and hydrothermally crystallized at 170 °C for 72 h. After filtration and washing, it is calcined at 500 °C for 4 h, denoted as organic hydrogen transfer promoter B8.

[0033] Example 6: Preparation of Propane Dehydrogenation Catalyst A1 Dissolve 0.021 g of H2PtCl6·6H2O and 0.026 g of Zn(AC)2·2H2O in a mixed solution of 1 ml of ethylenediamine and 15 ml of deionized water. Add 13 g of 25% tetrapropylammonium hydroxide, and dropwise add 8.9 ml of tetraethyl orthosilicate with stirring. After the addition is complete, continue stirring for 6 h. Transfer to a hydrothermal autoclave and hydrothermally crystallize at 170 °C for 72 h. After filtration and washing, calcine at 500 °C for 4 h. The obtained material is the PtZn@S-1 catalyst, denoted as propane dehydrogenation catalyst A1.

[0034] Example 7: Preparation of Propane Dehydrogenation Catalyst A2 Add 0.020 g of RuCl3·3H2O and 0.058 g of Cu(NO3)2·3H2O to a mixed solution of 1 ml of ethylenediamine and 15 ml of deionized water. Add 13 g of 25% tetrapropylammonium hydroxide, and dropwise add 8.9 ml of tetraethyl orthosilicate with stirring. After the addition is complete, continue stirring for 6 h. Transfer to a hydrothermal autoclave and hydrothermally crystallize at 170 °C for 72 h. After filtration and washing, calcine at 500 °C for 4 h. The obtained material is the RuCu@S-1 catalyst, denoted as propane dehydrogenation catalyst A2.

[0035] Test Example 1: Material Composition Analysis Whether the quinone material can be loaded inside the molecular sieve shell is a prerequisite for the material to have functions. First, use the organic element analysis method to analyze the B1-B8 materials obtained from different treatment processes, and the results are shown in Table 1.

[0036] Table 1

[0037] Note: 1. The analysis of hydrogen element is affected by the surface hydroxyl groups of the carrier, and the result is on the high side. Therefore, the mass of the corresponding quinone material is calculated according to the mass ratio of carbon element; 2. The B1* material is the material obtained by reducing the B1 material in a 10% H2-Ar mixed gas at 400 °C for 2 h.

[0038] In this method, the quinone material is first wrapped with SiO2, and then the S-1 molecular sieve shell is formed through subsequent hydrothermal treatment to obtain the L@S-1 material. Through the comparison in Table 1, we found that the content of the quinone material in the materials obtained without prior SiO2 wrapping (B2), without hydrothermal treatment (B3), and without adding surfactant in SiO2 wrapping (B4) is far lower than the given value. On the contrary, after complete wrapping and hydrothermal treatment, the calculated value and the given value have little deviation, and the solid loading of the quinone material is about 90%. At the same time, after H2 treatment, the hydrogen element ratio of this material is significantly increased (B1*), and the increase ratio conforms to the characteristics of anthraquinone hydrogenation, indicating that this material has the ability of hydrogenation in the corresponding environment.

[0039] Test Example 2: Evaluation of Propane Dehydrogenation Catalytic Activity The propane dehydrogenation catalysts A1 and A2 were respectively mixed, ground, pressed, and crushed into 20 - 40 mesh with the organic hydrogen transfer auxiliary materials B1 - B8 in the examples and comparative examples according to a certain ratio. The propane dehydrogenation performance was evaluated using 99.6% C3H8 raw material gas on an atmospheric pressure fixed bed micro-reactor. The total loading of the catalyst and the auxiliary was 1 g. The evaluation results of different materials are shown in Table 2.

[0040] Table 2

[0041]

[0042]

[0043]

[0044] The equilibrium conversion rate is an inherent value calculated according to the thermodynamic equilibrium equation at different reaction temperatures under atmospheric pressure for the pure propane dehydrogenation reaction. Changing the reaction pressure, introducing dilution gas, changing the product concentration, etc. can all break the reaction equilibrium.

[0045] The results in Table 2 show that the two catalysts, conventional PtZn@S-1 and RuCu@S-1, have relatively high catalytic activities. However, limited by the thermodynamic equilibrium, only relatively low yields can be obtained in the temperature range of 400 - 450°C, and the ratio to the thermodynamic equilibrium value is about 95%. When used in combination with the L@S-1 material, since part of the H2 generated in the reaction undergoes a tandem reaction with the quinone material, the partial pressure of H2 is reduced, and the propane conversion rate increases significantly. The yields of some materials reach 300 - 400% of the thermodynamic equilibrium value. Therefore, through the tandem reaction, it is possible to obtain an objective single-pass propylene yield at a relatively low reaction temperature, and the reduction of the reaction temperature will be beneficial to saving reaction energy consumption. For the organic hydrogen transfer auxiliaries in the three comparative examples B2, B3, and B4, due to the imperfect synthesis method, there are relatively few quinone materials confined in the molecular sieve shell layer, and the improvement effect is not obvious.

[0046] Test Example 3: Recycling Stability of Hydrogen Transfer Material Whether the hydrogen transfer material can be stably recycled is another key of this material. Use the A1 - B1 combination, where B1:A1 = 5 (mass ratio), the reaction temperature is 400°C, and the propane space velocity is 0.1 h -1 . Each reaction lasts for 2 h, and then it undergoes N2 purge - air regeneration - N2 purge regeneration. The regeneration temperature is 400°C, and the regeneration time is 0.5 h.

[0047] Figure 1It is a graph showing the change in catalytic performance of propane dehydrogenation catalyst A1 and organic hydrogen transfer assistant B1 in synergistic cycle for 200 times. The catalytic performance refers to the comprehensive index of propane conversion rate and propylene selectivity. If the long-term reaction fluctuation range is less than 5%, the catalytic performance can be considered stable. From Figure 1 it can be seen that within 200 cycles of the organic hydrogen transfer assistant B1, the propane conversion rate on the left vertical coordinate is between 12% and 13%, and the propylene selectivity on the right vertical coordinate is between 97.5% and 99%. The performance remains stable, and it has the characteristic of significantly improving the single-pass yield of propane dehydrogenation.

[0048] The above is a specific description of the preferred embodiment of the present invention. However, the present invention is not limited to the described embodiment. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A synthesis method for an organic hydrogen transfer promoter for propane dehydrogenation, characterized in that, The synthesis method includes the following steps: (1) Disperse the quinone compound and the surfactant in an alkaline ethanol-aqueous solution, and add TEOS for hydrolysis to obtain L@SiO2; (2) Hydrothermally crystallize the obtained L@SiO2 and the template agent solution, and obtain the organic hydrogen transfer promoter L@S-1 material through filtration, washing, and calcination.

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

4.

3. The synthesis method of an organic hydrogen transfer promoter for propane dehydrogenation according to claim 1, characterized in that, The surfactant is one of polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol, and the mass ratio of the quinone compound to the surfactant is 10:1 to 2:

1.

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

1.

5. The synthesis method of an organic hydrogen transfer assistant 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 to 0.6 mol / L.

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

100.

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

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

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