A hydrogen transfer material for a propane dehydrogenation reaction

Abstract

This invention belongs to the field of catalyst technology, specifically disclosing a hydrogen transfer material for propane dehydrogenation. The hydrogen transfer material of this invention is a composite oxide with a Ruddlesden-Popper type layered perovskite structure. This oxide has the characteristic of reacting with H2 in a temperature range of 400-550℃ without releasing water, thus avoiding the negative effects of water vapor on propane dehydrogenation. Its unique rock-salt layered structure has a rapid hydrogen intercalation-deintercalation capability. In the synergistic catalytic process with a propane dehydrogenation catalyst, it can react with H2 to reduce the hydrogen partial pressure in the propane dehydrogenation process, breaking through the thermodynamic equilibrium limit, thereby achieving propane dehydrogenation at a lower reaction temperature. This will significantly reduce the energy consumption of the process and improve the selectivity of propane dehydrogenation.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a hydrogen transfer material for propane dehydrogenation reaction. Background Technology

[0002] In recent years, driven by multiple factors such as automotive electrification, 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 equivalent per ton of propylene and emits about 2.2 tons of carbon. Based on a propylene production capacity of 25 million tons, the industry's carbon emissions exceed 50 million tons per year. Reducing reaction energy consumption is a crucial issue for the healthy development of this industry.

[0003] Propane catalytic dehydrogenation is a volumetric and strongly endothermic reaction. Due to thermodynamic equilibrium constraints, the reaction generally occurs at high temperatures of 550-600℃. High-temperature reactions bring a series of problems: (1) higher energy consumption is associated with temperature increases; (2) propane, propylene, and reaction intermediates are prone to coking and deactivation at high temperatures, reducing propylene selectivity, increasing carbon emissions, affecting the economics of the process, and increasing the difficulty and safety of the process; (3) catalysts are prone to loss and sintering at high temperatures, affecting catalyst activity and lifespan. 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 = (pC3H6▪pH2) / pC3H8. When the partial pressure of H2 is reduced by designing special catalysts or reaction processes, the partial pressure of propylene increases accordingly, resulting in a higher propylene yield. This makes it possible to obtain a considerable single-pass yield of propylene at a lower reaction temperature. For example, Suljo Linic et al. reported that a 140% propylene yield was achieved at 580 °C on a PtSn / SiO2 catalyst by selectively permeating H2 through a SiO2 / Al2O3 membrane material (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. This FeVO4 can be regenerated during the regeneration process, but the propylene yield of this process did not break through the thermodynamic limit (Science 381(2023)886).

[0005] Currently, these cutting-edge technologies still face significant barriers in industrial applications. Regarding membrane materials, large-scale membrane synthesis is difficult, expensive, and has limited throughput, making it difficult to meet industrial demands. As for chemical dehydrogenation, while the reaction of H2 with lattice oxygen can reduce the partial pressure of H2, the generated H2O has serious negative effects. Firstly, H2O molecules often adsorb more strongly on the catalyst surface than the propane feedstock, reducing the catalyst's adsorption of propane and severely impacting the conversion rate. For example, Cr-based catalysts show significant deactivation when the feed gas contains 0.3% water vapor. Secondly, H2O can damage the catalyst structure (e.g., converting Lewis acids to Brønsted active sites, or converting some alloys in alloy catalysts to oxides). Therefore, low-temperature propane dehydrogenation reactions still face considerable challenges.

[0006] Therefore, given the current problems of high propane dehydrogenation reaction temperature and large carbon emissions, the technical problem that this invention needs to solve is how to design a material that can break the thermodynamic equilibrium limitation and realize low-temperature propane dehydrogenation reaction. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a hydrogen transfer material for propane dehydrogenation reactions. This hydrogen transfer material works in conjunction with a propane dehydrogenation catalyst, reacting with the H2 generated during the reaction under specific conditions without releasing other substances, and recovering during regeneration. By transferring the H2 generated in the reaction, the thermodynamic equilibrium is broken, enabling low-temperature propane dehydrogenation.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a hydrogen transfer material for propane dehydrogenation reaction, wherein the chemical formula of the hydrogen transfer material is A. n+1 B n O 3n+1 Where A is at least one of Ca, Sr, Ba, and La, and B is at least one of Mn and Fe, and the crystal structure of the hydrogen transfer material is Ruddlesden-Popper type layered perovskite.

[0010] Furthermore, n in the chemical formula of the hydrogen transfer material is a positive integer.

[0011] Furthermore, the chemical formula of the hydrogen transfer material contains n = 2.

[0012] Furthermore, the hydrogen transfer material is prepared by one of the following methods: co-precipitation, sol-gel, or solid-phase synthesis.

[0013] Generally, hydroxides of metal ions dehydrate to form oxides during heating. However, the dehydration temperatures of hydroxides of alkaline earth metal ions and rare earth metal ions to form oxides are higher. For example, the dehydration temperature of Ca(OH)₂ to CaO is 580℃. This provides the possibility for reacting with H₂ at high temperatures without releasing H₂O. Ruddlesden-Popper type layered perovskite A n+ 1B n O 3n+1 (Where A is an alkaline earth or rare earth metal, and B is a transition metal), the reducible transition metal B is located in the layer, and the interlayer consists of AO rock salt layers with larger ionic radii. The reduction of H2 occurs through the insertion of hydrogen atoms into the interlayer AO, converting it to AOH, which remains unchanged due to its high thermal stability. During regeneration, hydrogen atoms are transferred to the gas phase and react with O2 to generate H2O. The dehydrogenation reaction and the reaction equations during the regeneration process are as follows:

[0014]

[0015] This process is similar to the insertion and extraction of Li in lithium-ion batteries. The unique layered structure of RP-type layered perovskites not only inhibits the dehydration of AOH but also facilitates the rapid insertion and extraction of hydrogen atoms. Unlike conventional oxides, the release of H2O occurs during the regeneration process rather than the reaction process, thus avoiding the side effects of H2O generation on the propane dehydrogenation reaction during the reaction.

[0016] A second aspect of the present invention provides an application of the above-mentioned hydrogen transfer material in a propane dehydrogenation reaction, wherein the hydrogen transfer material is used in conjunction with a propane dehydrogenation catalyst to promote a rightward shift of the equilibrium by transferring H2 generated in the reaction, thereby reducing the temperature of the propane dehydrogenation reaction.

[0017] Furthermore, the propane dehydrogenation catalyst is one of Cr2O3 / Al2O3 or PtSn / Al2O3.

[0018] Furthermore, the mass ratio of the hydrogen transfer material to the propane dehydrogenation catalyst is 0.1~2.

[0019] Furthermore, the propane dehydrogenation reaction is carried out at a temperature of 420–550 °C and a reaction space velocity of 0.1–10 h⁻¹. -1 .

[0020] The beneficial effects of this application are as follows:

[0021] The hydrogen transfer material described in this invention is a composite oxide with a Ruddlesden-Popper type layered perovskite structure. This oxide has the characteristic of reacting with H2 in a temperature range of 400-550℃ without releasing water, thus avoiding the negative effects of water vapor on propane dehydrogenation. Its unique rock-salt layered structure has a rapid hydrogen insertion-extraction capability. In the synergistic catalytic process with a propane dehydrogenation catalyst, it can react with H2 to reduce the hydrogen partial pressure in the propane dehydrogenation process, breaking through the thermodynamic equilibrium limit, thereby achieving propane dehydrogenation at a lower reaction temperature. This will significantly reduce the energy consumption of the process and improve the selectivity of propane dehydrogenation. Specific technical effects are as follows:

[0022] (1) The hydrogen transfer material of the present invention is RP layered perovskite material, which realizes the transfer of H2 in the reaction and regeneration process through hydrogen atom insertion and deintercalation. No water vapor is generated in the reaction process, thus avoiding the negative impact of water vapor on the reaction.

[0023] (2) The hydrogen transfer material of the present invention achieves high-speed hydrogen transfer, breaks through the thermodynamic equilibrium limitation, and the propane dehydrogenation reaction temperature is reduced by 50~100℃ compared with the conventional process, which will greatly reduce the energy consumption of the process and improve the selectivity of propane dehydrogenation. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of hydrogen transfer material B1 in Example 1.

[0025] Figure 2 These are TEM images of hydrogen transfer material B1 in Example 1. Images a, b, c, and d are taken from different regions of the TEM at different magnifications, with resolutions of: a: 20 nm, b: 2 nm, c: 5 nm, and d: 5 nm.

[0026] Figure 3 The H2-TPR spectra of hydrogen transfer materials B1 and B2 are shown.

[0027] Figure 4 The graph shows the change in synergistic catalytic cycle stability of propane dehydrogenation catalyst A1 and hydrogen transfer material B1. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Example 1: Preparation of hydrogen transfer material B1

[0030] 5.20 g of La(NO3)3·6H2O, 11.33 g of Ca(NO3)2·4H2O, and 14.32 g of 50 wt.% Mn(NO3)2 solution were dissolved in 200 ml of deionized water and denoted as solution A. 10.20 g of (NH4)2CO3 was dissolved in 200 ml of 0.2 mol / L ammonia solution and denoted as solution B. Solution A was added dropwise to solution B under stirring in a 60℃ water bath. After the addition was complete, aging continued for 12 h. After filtration, washing, and drying, the material was calcined at 900℃ for 5 h and then at 1300℃ for 24 h to obtain hydrogen transfer material, denoted as B1. Hydrogen transfer material B1 was characterized by XRD line scanning and high-resolution transmission electron microscopy, as shown in the figures below. Figure 1 and Figure 2 .Depend on Figure 1 It can be seen that this material possesses the typical diffraction peaks of perovskite-like materials. From... Figure 2 As shown in Figures b, c, and d, the material exhibits perovskite-like lattice fringes (100), (108), (110), and (003) at 2 nm and 5 nm. Figure 2 In Figure a, typical characteristic peaks along the C-axis, such as (004) and (002), are also present below 20 nm, with intergranular spacings of 0.56 nm and 1.13 nm, respectively, corroborating the two characterization results. These characteristic peaks along the C-axis correspond to a layered rock salt structure, in which only alkaline earth and rare earth metals exist between the layers, while the layers themselves are perovskite oxides formed by alkaline earth, rare earth metals, and transition metals. This interlayer structure provides a high-speed channel for the rapid insertion and extraction of hydrogen.

[0031] Comparative Example 1: Preparation of Hydrogen Transfer Material B2

[0032] 9.44 g of Ca(NO3)2·4H2O and 14.32 g of 50 wt.% Mn((NO3)2) solution were dissolved in 200 ml of deionized water, denoted as solution A. 8.50 g of (NH4)2CO3 was dissolved in 200 ml of 0.1 mol / L ammonia solution, denoted as solution B. Solution A was added dropwise to solution B under stirring in a 60°C water bath. After the addition was complete, aging continued for 12 h. After filtration, washing, and drying, the material was calcined at 1100°C for 5 h. The resulting hydrogen transfer material is denoted as B2.

[0033] Example 2: Preparation of hydrogen transfer material B3

[0034] 14.17 g Ca(NO3)2·4H2O, 14.32 g 50 wt.% Mn((NO3)2) solution, and 23.04 g citric acid were dissolved in 100 ml deionized water. The solution was evaporated to dryness at 80 °C by rotary evaporation. After foaming, a brown powder was obtained, which was then calcined at 900 °C for 5 h and at 1300 °C for 48 h. The resulting hydrogen transfer material was designated as B3.

[0035] Example 3: Preparation of hydrogen transfer material B4

[0036] 20 g of CaCO3 and 8.7 g of MnO2 were mixed and ball-milled for 1 hour, then calcined at 900℃ for 5 hours. The resulting powder was ground, pressed into Φ15 mm discs, and calcined at 1350℃ for 24 hours. The powder was then crushed, ground, and pressed again into Φ15 mm discs, and calcined at 1350℃ for 24 hours. The resulting hydrogen transfer material is designated B4.

[0037] Example 4: Preparation of hydrogen transfer material B5

[0038] 9.78 g La2O3, 2.96 g SrCO3, and 4.79 g Fe2O3 were mixed and ball-milled for 1 hour, then calcined at 900℃ for 5 hours. The resulting powder was ground and pressed into Φ15 mm discs, then calcined at 1400℃ for 24 hours. The powder was then crushed, ground, and pressed again into Φ15 mm discs, and calcined at 1400℃ for 24 hours. The resulting hydrogen transfer material was designated B5.

[0039] Example 5: Preparation of hydrogen transfer material B6

[0040] 8.66 g La(NO3)3·6H2O, 4.23 g Sr(NO3)2, 4.72 g Ca(NO3)2·4H2O, 7.16 g 50wt.% Mn((NO3)2 solution, 8.08 g Fe(NO3)3·9H2O, and 23.04 g citric acid were dissolved in 100 ml of deionized water. The solution was evaporated to dryness at 80 °C by rotary evaporation. After foaming, a brown powder was obtained, which was then calcined at 900 °C for 5 h and then at 1300 °C for 48 h. The resulting hydrogen transfer material was designated B6.

[0041] Example 6: Preparation of hydrogen transfer material B7

[0042] 14.17 g Ca(NO3)2·4H2O, 17.90 g 50 wt.% Mn((NO3)2) solution, and 25.34 g citric acid were dissolved in 100 ml deionized water. The solution was evaporated to dryness at 80 °C by rotary evaporation. After foaming, a brown powder was obtained, which was then calcined at 900 °C for 5 h and then at 1350 °C for 72 h. The resulting hydrogen transfer material was designated B7.

[0043] Example 7: Preparation of propane dehydrogenation catalyst A1

[0044] 2.7 g NaNO3 and 26.3 g CrO3 were dissolved in 4.7 g deionized water, and then impregnated onto 79 g γ-Al2O3 support by equal volume. The mixture was dried at 100 °C for 12 h, and then calcined at 750 °C for 5 h. The resulting propane dehydrogenation catalyst Cr2O3 / Al2O3 was denoted as A1.

[0045] Example 8: Preparation of propane dehydrogenation catalyst A2

[0046] 0.21 g KNO3, 0.53 g SnCl4·5H2O, and 0.26 g H2PtCl6·6H2O were dissolved in 19 ml of 0.1 mol / L HCl solution, and then impregnated onto 32 g γ-Al2O3 in equal volumes. The mixture was dried at 100 °C for 12 h, then calcined at 500 °C for 5 h, and finally reduced at 600 °C for 5 h in a 10% H2-Ar mixed gas. The resulting propane dehydrogenation catalyst, PtSn / Al2O3, was denoted as A2.

[0047] Performance testing

[0048] 1. H2-TPR characterization of hydrogen transfer materials B1 and B2

[0049] Whether the hydrogen transfer material releases water during the reduction process in the propane dehydrogenation reaction is a key issue in this invention. H2-TPR characterization technology was used to characterize and analyze B1 and B2. Two detectors were used to detect H2 consumption and H2O generation, respectively. The TCD detector mainly detects H2 consumption through changes in thermal conductivity, while the MS detector mainly detects the H2O signal in the mass spectrometer to study the H2O release temperature. The characterization results are shown below. Figure 3 As shown in the figure, for hydrogen transfer material B2 in Comparative Example 1, the signals on both detectors are similar, except that the release of H2O is slightly delayed. This indicates that the reduction and release of H2O are basically synchronous, because stepwise calcination was not performed during the preparation process. Conversely, for material B1, the TCD detector shows a significant reduction peak in the temperature range of 400–650 °C, while the MS detector only shows a significant H2O release peak after 550 °C, with a noticeable tailing phenomenon. This indicates that the release of H2O is significantly delayed in this material. Therefore, within the temperature window of 400–550 °C, there exists a phenomenon of reacting only with H2 without releasing H2O, which provides a potential for co-catalysis with propane dehydrogenation catalysts.

[0050] 2. Synergistic effect test of hydrogen transfer materials and propane dehydrogenation catalyst

[0051] Propane dehydrogenation catalysts A1 and A2 were mixed with hydrogen transfer materials B1-B7 obtained in Examples 1-6 and Comparative Example 1 in a certain proportion, ground, pressed, and crushed into 20-40 mesh. The propane dehydrogenation performance was evaluated using 99.6% C3H8 feed gas in an atmospheric pressure fixed-bed microreactor with a catalyst loading of 2 g. The evaluation results of different materials are shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055]

[0056]

[0057] The equilibrium conversion rate is an inherent value calculated from the thermodynamic equilibrium equation for the dehydrogenation reaction of pure propane at different reaction temperatures under normal pressure. Changing the reaction pressure, introducing dilution gas, or altering the product concentration can all disrupt the reaction equilibrium.

[0058]

[0059] Table 1 shows that conventional Cr-based (A1) and Pt-based (A2) catalysts require relatively high reaction temperatures to achieve considerable propane dehydrogenation yields, with yield-to-equilibrium conversion ratios ranging from 86% to 97%, clearly constrained by thermodynamic equilibrium. When a hydrogen transfer promoter is added, the propane conversion at different temperatures increases significantly, with yield-to-equilibrium conversion ratios ranging from 140% to 300%, indicating a breakthrough in thermodynamic equilibrium limitations. Compared to the absence of a hydrogen transfer promoter, the dehydrogenation temperature decreases by 50-100°C for the same propylene yield. This temperature reduction brings a series of benefits, including reduced energy consumption, increased selectivity, improved catalyst stability, and enhanced resistance to carbon deposition. Conversely, the hydrogen transfer material B2 in Comparative Example 1 exhibits a significant decrease in catalytic activity due to the release of H2O during use, with the decrease becoming more pronounced with increasing dosage. This demonstrates the inhibitory effect of H2O on the propane dehydrogenation reaction. This highlights the necessity of the material in this invention reacting with H2 without releasing water.

[0060] 3. Stability testing of hydrogen transfer material B1

[0061] The ability of the hydrogen transfer material to cycle stably is another key factor. Using an A1-B1 combination, where B1:A1 = 1 (mass ratio), the reaction temperature was 500℃ and the propane space velocity was 1 h⁻¹. -1 Each reaction lasts 0.5 hours, followed by N2 purging-air regeneration-N2 purging regeneration. The regeneration temperature is 400℃ and the regeneration time is 0.5 hours.

[0062] Figure 4 This graph shows the catalytic performance changes of propane dehydrogenation catalyst A1 and hydrogen transfer material B1 after 200 synergistic cycles. Catalytic performance refers to a comprehensive indicator of propane conversion and propylene selectivity; if the long-term reaction fluctuation is less than 5%, the catalytic performance is considered stable. Figure 4It can be seen that within 200 cycles of reaction, the propane conversion rate on the left ordinate is 31.5%-33%, and the propylene selectivity on the right ordinate is 94%-96%, maintaining stable performance and demonstrating a significant improvement in the single-pass yield of propane dehydrogenation.

[0063] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. The application of a hydrogen transfer material in the propane dehydrogenation reaction, characterized in that, The hydrogen transfer material is used in conjunction with a propane dehydrogenation catalyst, wherein the propane dehydrogenation catalyst is PtSn / Al2O3; the propane dehydrogenation reaction is carried out at a temperature of 420–550 °C and a reaction space velocity of 0.1–10 h⁻¹. -1 The chemical formula of the hydrogen transfer material is A. n+1 B n O 3n+1 Where A is Ca, B is Mn, n is 2, and the crystal structure of the hydrogen transfer material is Ruddlesden-Popper type layered perovskite; The mass ratio of the hydrogen transfer material to the propane dehydrogenation catalyst is 2.

2. The application of the hydrogen transfer material according to claim 1 in the propane dehydrogenation reaction, characterized in that, The hydrogen transfer material can be prepared by any one of the following methods: co-precipitation, sol-gel method, or solid-phase synthesis.

3. The application of the hydrogen transfer material according to claim 2 in the propane dehydrogenation reaction, characterized in that, The coprecipitation method includes the following steps: The nitrate containing element A and the nitrate containing element B are dissolved in deionized water to obtain solution A. (NH4)2CO3 is dissolved in ammonia solution to obtain solution B. Solution A is added dropwise to solution B under water bath heating. The mixture is aged, filtered, washed, dried, and calcined in steps to obtain the hydrogen transfer material.

4. The application of the hydrogen transfer material according to claim 2 in the propane dehydrogenation reaction, characterized in that, The sol-gel method includes the following steps: The nitrate containing element A, the nitrate containing element B, and citric acid are dissolved in deionized water, rotary evaporated, foamed to obtain powder, and then calcined in steps to obtain hydrogen transfer material.

5. The application of the hydrogen transfer material according to claim 2 in the propane dehydrogenation reaction, characterized in that, The solid-phase synthesis method includes the following steps: The oxide containing element A and the oxide containing element B are mixed, ball-milled, calcined, ground and pressed into tablets, calcined a second time, crushed and ground, pressed into tablets again and calcined to obtain the hydrogen transfer material.

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