A high-stability boron-based catalyst based on rare earth ion bridging anchoring, its preparation method and application in the dehydrogenation of light alkanes

Abstract

The present invention discloses a high-stability boron-based catalyst based on rare earth ion bridging anchoring and its preparation method and light alkane dehydrogenation application. The catalyst of the present invention includes γ-Al2O3 carrier, a rare earth metal oxide intermediate layer and B2O3 active component sequentially loaded on the carrier, wherein the rare earth metal is at least one of Gd, Ce, La, and Y, and the loading amount of the rare earth metal oxide in the catalyst is 5-30%, and the loading amount of B2O3 is 5-35%. The present invention solves the problem of weak interfacial binding force between traditional alumina carrier and B-O active phase by constructing a "rare earth ion-mediated bridging anchoring" system, uses rare earth elements to form high-density anchoring sites on the carrier surface, and then further loads B2O3, forming a "B2O3 active phase-rare earth bridge-carrier" three-dimensional stabilization architecture. The stability of the catalyst of the present invention in light alkane dehydrogenation is high, and it has important industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the field of thermal catalysis technology, and in particular to a preparation technology of a high-stability boron-based catalyst based on rare earth ion bridging anchoring and its application in the dehydrogenation of light alkanes. Background Art

[0002] Propylene is one of the most important basic raw materials in modern petrochemicals and is mainly used to produce high-value-added chemicals such as polypropylene (accounting for 65%) and acrylonitrile (12%) (Green Chemistry, 2021, 23(24): 9747-9799.). Currently, about 70% of the industrial propylene supply relies on naphtha steam cracking and refinery FCC by-product processes. However, these two technical routes have inherent disadvantages such as low propylene yield (usually <25%) and high energy consumption (>25GJ / ton propylene) (Fuel, 2022, 321: 124089; Chemical reviews 114.20 (2014): 10613-10653; Chem. Rev., 2014, 114, 10613-10653).

[0003] Among various propane conversion processes, oxidative dehydrogenation of propane (ODHP) technology offers significant advantages due to its unique reaction mechanism. By introducing an oxidant to overcome thermodynamic equilibrium constraints, this technology can increase single-pass conversion rates to over 50%. The oxidative reaction environment effectively suppresses carbon deposits, extending the catalyst's continuous operating time by 5-8 times compared to direct dehydrogenation processes. Furthermore, the exothermic nature of the reaction reduces overall energy consumption by 30-40%. These technical and economic advantages make ODHP considered the next-generation propane conversion technology with the greatest potential for industrialization.

[0004] In terms of catalyst system selection, although traditional transition metal oxides (such as V-Mo-Fe-based catalysts) have high intrinsic activity, their strong oxidizing properties lead to serious over-oxidation problems, with propylene selectivity generally below 60%, and active components are prone to sintering at high temperatures. In contrast, boron-based catalysts exhibit unique catalytic performance advantages in propane oxidative dehydrogenation reactions. Specifically: i) Selectivity advantage: Transition metal oxide catalysts often lead to over-oxidation of propane to produce CO due to their strong CH bond activation ability. xByproducts, such as propylene, are generally less than 60% selectivity. However, boron-based catalysts (such as B2O3 and h-BN) can effectively inhibit deep oxidation due to their moderate surface acidity and unique BO active sites, increasing propylene selectivity to over 80% (Science, 2016, 354(6319): 1570-1573). ii) Anti-coking performance: Transition metal catalysts are easily deactivated by carbon deposition during the reaction, typically requiring frequent regeneration. Boric acid species formed on the surface of boron-based materials can inhibit carbon deposition and significantly extend catalyst life. iii) Structural stability: Transition metal oxides are prone to phase transformation or sintering at high temperatures, while boron species can form stable dispersed structures on the support surface, such as BO3 triangular units or BO4 tetrahedra, which are beneficial for maintaining the stability of the active sites (Angewandte Chemie International Edition, e202507525; Catalysis Today, 2022, 402: 248-258). However, existing boron-based catalysts still have two key technical bottlenecks: one is the insufficient density of active sites, which leads to low volumetric space-time yield; the other is that boron species are easily volatilized and lost at high temperatures, seriously affecting the long-term stability of the catalyst.

[0005] To address the above technical difficulties, the present invention uses a rare earth metal-alumina composite carrier to construct anchoring sites, and utilizes the interface structure formed by the rare earth metal and the γ-Al2O3 carrier to provide high-density anchoring sites for boron species; using gradient temperature-controlled crystal growth technology, the high dispersion of B2O3 is successfully achieved, and excellent catalytic performance (propane conversion rate >40%, olefin selectivity >80%) and long-term stability (stable operation at 520°C >200 h) are demonstrated in the propane oxidative dehydrogenation (ODHP) reaction, providing key material support for the industrial application of ODHP technology. Summary of the Invention

[0006] The present invention aims to solve the technical problems of low dispersion, insufficient exposure of active sites, poor high-temperature stability, etc. of supported boron oxide catalysts in the prior art, and to provide a high-stability boron-based catalyst based on rare earth ion bridging anchoring and a preparation method thereof.

[0007] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0008] A high-stability boron-based catalyst based on rare earth ion bridging anchoring includes a γ-Al2O3 carrier, a rare earth metal oxide intermediate layer sequentially loaded on the carrier, and a B2O3 active component. The rare earth metal is at least one of Gd, Ce, La, and Y. The loading amount of the rare earth metal oxide in the catalyst is 5-30%, and the loading amount of B2O3 is 5-35%.

[0009] Furthermore, the loading amount of rare earth metal oxide in the catalyst is 15-20%, and the loading amount of B2O3 is 10-33%.

[0010] Furthermore, the specific surface area of ​​the γ-Al2O3 is 50-300 m² / g, and the average pore diameter is 15-25 nm.

[0011] The method for preparing a high-stability boron-based catalyst based on rare earth ion bridging anchoring comprises the following steps:

[0012] S1: preparing an aqueous solution of a nitrate of a rare earth metal M, wherein the rare earth metal M is at least one of Gd, Ce, La, and Y, to obtain a solution A;

[0013] S2: impregnating the γ-Al2O3 support in solution A of step S1, drying after sufficient impregnation, and then transferring to a muffle furnace for high-temperature calcination to obtain a support precursor modified with a rare earth metal M oxide;

[0014] S3: The precursor of step S2 is immersed in a boric acid aqueous solution, dried after sufficient immersion, and then transferred to a muffle furnace for high-temperature calcination to obtain the final catalyst.

[0015] Furthermore, in step S2 or S3, the calcination temperature is 400-700° C., and the calcination time is 1-4 hours.

[0016] Furthermore, in step S2 or S3, the calcination temperature is 500-600° C., and the calcination time is 1-3 hours.

[0017] The present invention also discloses the use of the high-stability boron-based catalyst based on rare earth ion bridging anchoring in catalyzing the oxidative dehydrogenation reaction of light alkanes.

[0018] Furthermore, the low-carbon alkane is propane, the catalyst is loaded into a fixed-bed reactor, the reaction gas is a C3H8-O2-N2 mixed gas with a volume ratio of 1:(0.5-1.5):(1-9), and the reaction gas is passed into the catalyst bed at a catalytic reaction temperature to carry out a catalytic propane oxidative dehydrogenation reaction. The catalytic reaction temperature is 450-550°C, the reaction pressure is atmospheric pressure, and the reaction space velocity is 10000-40000 mL / (g cat ·h).

[0019] Furthermore, the catalytic reaction temperature is 520-525 °C, and the reaction space velocity is 15000-20000 mL / (g cat ·h).

[0020] The beneficial effects of the present invention are:

[0021] 1) This invention innovatively overcomes key technical challenges of existing boron oxide catalysts, such as low dispersion, poor thermal stability, and insufficient catalytic activity, resulting in the development of a highly dispersed supported boron oxide catalyst. This catalyst exhibits excellent catalytic performance (propane conversion >40%, olefin selectivity >80%) and long-term stability (stable operation at 520°C for >200 h) in the oxidative dehydrogenation of propane (ODHP). This provides a breakthrough solution for the industrial application of boron-based catalytic materials and is of great significance in promoting the development of efficient conversion technologies for light alkanes.

[0022] 2) This patent proposes a novel strategy for designing highly stable catalysts based on enhanced rare earth ion interfacial bonding. By constructing a "rare earth ion-mediated bridging anchoring" system, the challenge of weak interfacial bonding between conventional alumina supports and the BO active phase is overcome. Specifically, a surface islanding modification technique using rare earth elements (Gd, Ce, La, Y, etc.) is employed to form a high density of anchoring sites on the support surface. Chemical locking of the active sites is achieved through a quaternary bridge-bonding structure of BO-REE-Al, where REE represents the rare earth metal. This creates a three-dimensional stabilized "B2O3 active phase-rare earth bridge-support" architecture, resulting in excellent catalytic stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the N2 adsorption-desorption isotherm of γ-Al2O3 and the corresponding pore size distribution curve.

[0024] Figure 2A It is the average reaction result of 10 wt% B2O3 / γ-La2O3 catalyst in Example 1 at catalytic reaction temperatures of 470℃ and 490℃ within catalytic time of 2h.

[0025] Figure 2B It is the average reaction result of 10 wt% B2O3 / γ-Gd2O3 catalyst in Example 1 at a catalytic reaction temperature of 470°C within a catalytic time of 2 h.

[0026] Figure 2C These are the reaction results of the 10 wt% B2O3 / γ-Y2O3 catalyst in Example 1 at different catalytic temperatures and reaction times.

[0027] Figure 2D These are the reaction results of the 10 wt% B2O3 / γ-CeO2 catalyst in Example 1 at different catalytic temperatures and reaction times.

[0028] Figure 3 It is the average reaction result of 7 catalysts with different B2O3 loadings in Example 2 at a catalytic reaction temperature of 520°C within a catalytic time of 2 hours.

[0029] Figure 4A These are the reaction results of catalytic temperature, propane conversion rate and target product selectivity of the 33 wt% B2O3-5 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times in Example 3.

[0030] Figure 4B These are the reaction results of catalytic temperature, propane conversion rate and target product selectivity of the 33 wt% B2O3-10 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times in Example 3.

[0031] Figure 4C These are the reaction results of catalytic temperature, propane conversion rate and target product selectivity of the 33 wt% B2O3-20 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times in Example 3.

[0032] Figure 4D These are the reaction results of catalytic temperature, propane conversion rate and target product selectivity of the 33 wt% B2O3-30 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times in Example 3.

[0033] Figure 5 These are the catalytic reaction temperature conditions and reaction results of the catalytic reaction of the 33 wt% B2O3-10 wt% MgO / γ-Al2O3 catalyst in Comparative Example 1 at different catalytic times.

[0034] Figure 6 These are the catalytic reaction temperature conditions and reaction results of the catalytic reaction of the 33 wt% B2O3-10 wt% ZrO2 / γ-Al2O3 catalyst in Comparative Example 2 at different catalytic times.

[0035] Figure 7 These are the catalytic reaction temperature conditions and reaction results of the catalytic reaction of the 33 wt% B2O3-10 wt% ZnO / γ-Al2O3 catalyst in Comparative Example 3 at different catalytic times.

[0036] Figure 2C-2D 、 Figures 4A-4D as well as Figure 5-Figure 7 In the figure, the selectivity on the ordinate represents the total olefin selectivity of "propylene + ethylene". DETAILED DESCRIPTION

[0037] It should be noted that the embodiments described herein are only exemplary implementations of the technical solutions of the present invention, and are not an exhaustive enumeration of the scope of protection. The detailed description of the embodiments in this section is intended to help understand the core principles and implementation methods of the present invention, rather than to limit the scope of the claims. It should be understood that based on the technical concepts disclosed in this specification, any technical solution obtained by any person skilled in the art through equivalent replacement, routine experiments or technical extension without the need for creative work should be deemed to fall within the scope of protection of the present invention.

[0038] In the following examples, a fixed bed reactor and an online gas chromatography system were used for real-time detection (fixed bed model and manufacturer: Betterwork Xiamen Baidewo Intelligent Technology Co., Ltd.; online chromatograph model and manufacturer: GC2060 Shanghai Ruimin Instrument Co., Ltd.).

[0039] The N2 adsorption-desorption isotherms and the corresponding pore size distribution curves of the γ-Al2O3 carriers used in the examples and comparative examples of the present invention are shown in FIG. Figure 1 As shown, it can be seen that the specific surface area of ​​γ-Al2O3 is 129.6 m² / g, the average pore diameter is 20.6 nm, and the adsorption-desorption curve type is Type II.

[0040] Example 1. Comparison of catalytic experiments with different supported catalysts

[0041] 1. Preparation of different metal oxide supported catalysts, comprising the following steps:

[0042] a) Boric acid solution preparation: Weigh 177.6 mg of boric acid (H3BO3) and dissolve it in 8 mL of 80°C deionized water. Stir until completely dissolved to obtain the boric acid solution.

[0043] b) Over-volume impregnation: Add 1 g of the support to the above boric acid solution and continue stirring in an 80 °C water bath until the water is completely evaporated.

[0044] c) Drying and calcination: The impregnated sample was dried in a hot air drying oven at 80 °C for 12 h, then transferred to a muffle furnace and heated to 550 °C at a heating rate of 5 °C / min. The sample was calcined at this temperature for 2 h and then naturally cooled to room temperature to obtain the catalyst.

[0045] According to the above catalyst preparation process, when the carrier in step b) is La2O3, Gd2O3, Y2O3 or CeO2, a series of catalysts with different carriers are prepared: 10 wt% B2O3 / La2O3, 10 wt% B2O3 / Gd2O3, 10 wt% B2O3 / Y2O3, 10 wt% B2O3 / CeO2.

[0046] 2. Propane Oxidative Dehydrogenation Activity Test

[0047] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal amount of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors).

[0048] According to the above catalytic reaction process, the average reaction results of 10 wt% B2O3 / γ-La2O3 catalyst at catalytic reaction temperature of 470℃ and 490℃ within catalytic time of 2h are shown in Figure 2A As shown in Figure 2, the average reaction results of 10 wt% B2O3 / γ-Gd2O3 catalyst at a catalytic reaction temperature of 470℃ within a catalytic time of 2h are shown in Figure 2. Figure 2B shown.

[0049] The reaction results of 10 wt% B2O3 / γ-Y2O3 catalyst at different catalytic temperatures and reaction times are shown in Figure 2C .from Figure 2C It can be seen that the propane conversion rate dropped rapidly after the catalytic time of 32.5 h, indicating that the stability of the 10 wt% B2O3 / γ-Y2O3 catalyst was insufficient.

[0050] The reaction results of 10 wt% B2O3 / γ-CeO2 catalyst at different catalytic temperatures and reaction times are shown in Figure 2D .

[0051] from Figure 2A-2D From the comparison of the reaction results, it can be seen that compared with La2O3 or Gd2O3 carriers, when the catalyst carrier is selected as Y2O3 or CeO2, the catalyst has better catalytic activity in catalyzing the dehydrogenation of light alkanes to olefins.

[0052] Example 2: Preparation of x wt% B2O3-20 wt% CeO2 / γ-Al2O3 (where x = 0, 5, 10, 15, 20, 25, 33) catalyst and performance test of propane oxidative dehydrogenation

[0053] 1. Preparation of 20 wt% CeO2 / γ-Al2O3 support

[0054] 1) Preparation of precursor solution: Accurately weigh 504.6 mg of cerium nitrate hexahydrate (Ce(NO₃)₃·6H₂O, purity ≥99.9%) and dissolve it in 900 μL of deionized water. Ultrasonicate for 5 min until completely dissolved to prepare a cerium precursor solution.

[0055] 2) Equal volume impregnation: 1.0 g of γ-Al2O3 support was impregnated in each of the above solutions and allowed to stand at room temperature for 12 h to ensure sufficient adsorption.

[0056] 3) Drying and Calcination: The impregnated sample was transferred to a forced air drying oven and dried at 80°C for 12 h. The sample was then placed in a programmable temperature-controlled muffle furnace and heated from room temperature to 550°C at a rate of 5°C / min. The sample was calcined at this temperature for 2 h and then cooled in the furnace to produce a 20 wt% CeO2 / γ-Al2O3 support.

[0057] 2. Preparation of x wt% B2O3-20 wt% CeO2 / γ-Al2O3 catalyst

[0058] a) Preparation of boric acid solution: Weigh 0 mg, 88.8 mg, 177.6 mg, 266.4 mg, 355.3 mg, 444.1 mg, and 586.2 mg of boric acid (H3BO3), respectively, and dissolve them in 8 mL of 80°C deionized water. Stir until completely dissolved to obtain boric acid solutions of different concentrations.

[0059] b) Over-volume impregnation: Add 1 g of 20 wt% CeO2 / γ-Al2O3 support to each of the above solutions and continue stirring in an 80 °C water bath until the water is completely evaporated.

[0060] c) Drying and calcination: The impregnated samples were dried in a hot air drying oven at 80 °C for 12 h, then transferred to a muffle furnace and heated to 550 °C at a rate of 5 °C / min and calcined at this temperature for 2 h. After cooling to room temperature, seven catalysts with different B2O3 loadings were prepared: 20 wt% CeO2 / γ-Al2O3, 5 wt% B2O3-20 wt% CeO2 / γ-Al2O3, 10 wt% B2O3-20 wt% CeO2 / γ-Al2O3, 15 wt% B2O3-20 wt% CeO2 / γ-Al2O3, 20 wt% B2O3-20 wt% CeO2 / γ-Al2O3, 25 wt% B2O3-20 wt% CeO2 / γ-Al2O3, 33 wt% B2O3-20 wt% CeO2 / γ-Al2O3, and 35 wt% B2O3-20 wt% CeO2 / γ-Al2O3. wt%CeO2 / γ-Al2O3.

[0061] 3. Propane oxidative dehydrogenation activity test

[0062] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h), the reaction temperature was controlled at 520 °C, and the reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors).

[0063] According to the above catalytic reaction process, the average reaction results of 7 catalysts with different B2O3 loadings at a catalytic reaction temperature of 520℃ within a catalytic time of 2h are as follows: Figure 3 shown. Figure 3 The effects of different B2O3 loadings on the catalytic performance of propane oxidative dehydrogenation are shown. When B2O3 is not loaded (0 wt%), the catalyst exhibits a significant deep oxidation tendency (CO x Selectivity>80 wt%). With the increase of B2O3 loading, the deep oxidation activity of the catalyst is gradually suppressed. It is worth noting that when the loading reaches 33 wt%, the system shows the best catalytic performance: CO x The selectivity dropped significantly to below 10 wt%, while the olefin selectivity increased to over 80 wt%. This result indicates that a 33 wt% B2O3 loading effectively regulates the reaction pathway, suppressing side reactions while maximizing the yield of the target product, and is therefore determined to be the optimal loading condition.

[0064] Example 3: Preparation of 33 wt% B2O3-x wt% CeO2 / γ-Al2O3, x=5, 10, 20, 30 catalysts and performance testing of propane oxidative dehydrogenation

[0065] 1. Catalyst Preparation

[0066] 1) Preparation of precursor solutions: Accurately weigh 126.2 mg, 252.3 mg, 504.6 mg, and 756.9 mg of cerium nitrate hexahydrate (Ce(NO3)3·6H2O, purity ≥99.9%), respectively, dissolve each in 900 μL of deionized water, and sonicate for 5 min until completely dissolved to prepare a series of cerium precursor solutions.

[0067] 2) Equal volume impregnation: 1.0 g of γ-Al2O3 support was impregnated in each of the above solutions and allowed to stand at room temperature for 12 h to ensure sufficient adsorption.

[0068] 3) Drying and Calcination: The impregnated samples were transferred to a forced-air drying oven and dried at 80°C for 12 h. The samples were then placed in a programmable temperature-controlled muffle furnace and heated from room temperature to 550°C at a rate of 5°C / min. The samples were then calcined at this temperature for 2 h and then cooled in the furnace to produce a series of catalyst supports with varying CeO2 loadings: 5 wt% CeO2 / γ-Al2O3, 10 wt% CeO2 / γ-Al2O3, 20 wt% CeO2 / γ-Al2O3, and 30 wt% CeO2 / γ-Al2O3.

[0069] 4) Dissolve 586.2 mg of boric acid (H3BO3) in 8 mL of 80°C deionized water and stir until completely dissolved to obtain a boric acid solution. Add 1 g of catalyst supports with varying CeO2 loadings (5 wt% CeO2 / γ-Al2O3, 10 wt% CeO2 / γ-Al2O3, 20 wt% CeO2 / γ-Al2O3, or 30 wt% CeO2 / γ-Al2O3) to the boric acid solution and continue stirring in an 80°C water bath until the water is completely evaporated.

[0070] 5) Finally, the obtained sample was placed in a hot air drying oven at 80 ℃ for 12 h, then transferred to a muffle furnace, heated to 550 ℃ at a heating rate of 5 ℃ / min, calcined at this temperature for 2 h, and naturally cooled to room temperature. Finally, a series of catalysts with different CeO2 loadings were prepared: 33wt%B2O3-5wt%CeO2 / γ-Al2O3, 33wt%B2O3-10wt%CeO2 / γ-Al2O3, 33wt%B2O3-20wt%CeO2 / γ-Al2O3, and 33 wt%B2O3-30 wt%CeO2 / γ-Al2O3.

[0071] 2. Propane Oxidative Dehydrogenation Activity Test

[0072] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal amount of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors).

[0073] According to the above catalytic reaction process, the reaction results of catalytic temperature, propane conversion rate and target product selectivity of 33 wt% B2O3-5 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times are shown in Figure 4A shown. Figure 4A The catalytic performance and stability of a 33 wt% B2O3-5 wt% CeO2 / γ-Al2O3 catalyst at various reaction temperatures were demonstrated. In the initial stages of the catalytic reaction, propane conversion increased significantly from 6.5% to 43.0% as the temperature increased from 490°C to 520°C, while olefin selectivity remained high at approximately 82.0% to 91.4%. However, after a cyclic test (60 h) at 520°C, the catalyst gradually deactivated, with propane conversion decreasing from 43.0% to 36.0%, indicating that catalyst stability under high-temperature conditions requires optimization.

[0074] According to the above catalytic reaction process, the reaction results of catalytic temperature, propane conversion rate and target product selectivity of 33 wt% B2O3-10 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times are shown in Figure 4B shown. Figure 4B The catalytic performance and stability of a 33 wt% B2O3-10 wt% CeO2 / γ-Al2O3 catalyst at various reaction temperatures were demonstrated. In the initial stages of the catalytic reaction, propane conversion increased significantly from 4.0% to 43.0% as the temperature increased from 490°C to 520°C, while olefin selectivity remained consistently high at approximately 80.0% to 91.0%. However, after a cyclic test (20 h) at 520°C, the catalyst gradually deactivated, with propane conversion decreasing from 43.0% to 35.0%, indicating that catalyst stability under high-temperature conditions requires optimization.

[0075] According to the above catalytic reaction process, the reaction results of catalytic temperature, propane conversion rate and target product selectivity of 33 wt% B2O3-20 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times are shown in Figure 4C shown. Figure 4C The catalytic performance and long-term stability of the 33wt% B2O3-20wt% CeO2 / γ-Al2O3 catalyst at various reaction temperatures were demonstrated. As the reaction temperature increased from 490°C to 520°C, the propane conversion increased significantly from 6.0% to 45.0%, while the olefin selectivity remained consistently high, ranging from approximately 80.0% to 89.0%. Notably, after a 200-h long-term cycle test at 520°C, the catalyst showed no significant deactivation, with the propane conversion only slightly decreasing from 43.0% to 39.0%, demonstrating the catalyst's excellent stability under high-temperature conditions.

[0076] According to the above catalytic reaction process, the reaction results of catalytic temperature, propane conversion rate and target product selectivity of 33 wt% B2O3-30 wt% CeO2 / γ-Al2O3 catalyst at different catalytic times are shown in Figure 4D shown. Figure 4D The catalytic performance of the 33wt% B2O3-30wt% CeO2 / γ-Al2O3 catalyst in the temperature range of 490-530°C was demonstrated. In the initial stage of the catalytic reaction, propane conversion increased from 4.6% to 15.6% within the 490-520°C range, while olefin selectivity remained high at 83.0%-90.0%. Notably, propane conversion only significantly increased to 44.0% when the temperature was raised to 530°C, indicating that the catalyst's low-temperature activity still needs to be optimized.

[0077] In summary, 33 wt% B2O3-20 wt% CeO2 / γ-Al2O3 catalyst is the best catalyst.

[0078] Figures 4A-4D In the embodiment, the conversion rate and selectivity are 0, which means that the catalytic reaction stops running for a period of time.

[0079] Comparative Example 1: Preparation of 33 wt% B2O3-10 wt% MgO / γ-Al2O3 Catalyst and Performance Test of Propane Oxidative Dehydrogenation

[0080] 1. Preparation of 10 wt% MgO / γ-Al2O3 Support

[0081] a) Accurately weigh 1055.0 mg of magnesium nitrate hexahydrate (Mg(NO₃)₂·6H₂O, purity ≥99.9%) and dissolve it in 1.0 mL of deionized water. Ultrasonicate for 5 min until completely dissolved to prepare a magnesium precursor solution.

[0082] b) The above solution was loaded onto 1.0 g of γ-Al2O3 support by the equal volume impregnation method and allowed to stand at room temperature for 12 h;

[0083] c) Dry the sample in a forced air drying oven at 80°C for 12 h;

[0084] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, calcined at this temperature for 2 h, and then cooled in the furnace to obtain a 10 wt% MgO / γ-Al2O3 support.

[0085] 2. Preparation of 33 wt% B2O3-10 wt% MgO / γ-Al2O3 Support

[0086] a) Weigh 586.2 mg of boric acid (H3BO3, purity ≥99.5%) and dissolve it in 8.0 mL of 80°C ultrapure water. Stir magnetically (500 rpm) until completely dissolved.

[0087] b) Add 1.0 g of the 10 wt% MgO / γ-Al2O3 support prepared above and stir in an 80°C water bath (300 rpm) until the solution is completely evaporated;

[0088] c) Dry the sample in a forced air drying oven at 80°C for 12 hours;

[0089] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, and the mixture was calcined at this temperature for 2 hours and then cooled in the furnace to obtain a 33 wt% B2O3-10 wt% MgO / γ-Al2O3 catalyst.

[0090] 3. Propane Oxidative Dehydrogenation Activity Test

[0091] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal amount of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h), the reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors).

[0092] The catalytic reaction temperature conditions and reaction results of the 33 wt% B2O3-10 wt% MgO / γ-Al2O3 catalyst in Comparative Example 1 at different catalytic times are summarized in Figure 5 In. From Figure 5 It can be seen that the propane conversion rate of the catalyst in Comparative Example 1 dropped from about 50% to about 38% after 51 hours at 525°C, and deep oxidation occurred at the same time. Then the temperature was lowered to 520°C for a catalytic reaction test, and it was found that the propane conversion rate dropped from 46% to 40% after 28 hours. As the temperature decreased, deep oxidation was not suppressed, and the catalytic activity also decreased. Therefore, the catalytic effect of MgO as a catalyst in the intermediate layer was not good.

[0093] Comparative Example 2: Preparation of 33 wt% B2O3-10 wt% ZrO2 / γ-Al2O3 Catalyst and Performance Test of Propane Oxidative Dehydrogenation

[0094] 1. Preparation of 10 wt% ZrO2 / γ-Al2O3 support

[0095] a) Accurately weigh 470.6 mg of zirconium nitrate pentahydrate (Zr(NO₃)₂·5H₂O, purity ≥99.9%) and dissolve it in 1.0 mL of deionized water. Ultrasonicate for 5 minutes until completely dissolved to prepare a zirconium precursor solution.

[0096] b) The above solution was loaded onto 1.0 g of γ-Al2O3 support by the equal volume impregnation method and allowed to stand at room temperature for 12 h;

[0097] c) Dry the sample in a forced air drying oven at 80°C for 12 h;

[0098] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, calcined at this temperature for 2 h, and then cooled in the furnace to obtain a 10 wt% ZrO2 / γ-Al2O3 support.

[0099] 2. Preparation of 33 wt% B2O3-10 wt% ZrO2 / γ-Al2O3 support

[0100] a) Weigh 586.2 mg of boric acid (H3BO3, purity ≥99.5%) and dissolve it in 8.0 mL of 80°C ultrapure water. Stir magnetically (500 rpm) until completely dissolved.

[0101] b) Add 1.0 g of the 10 wt% ZrO2 / γ-Al2O3 support prepared above and stir in an 80 °C water bath (300 rpm) until the solution is completely evaporated;

[0102] c) Dry the sample in a forced air drying oven at 80°C for 12 h;

[0103] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, calcined at this temperature for 2 h, and then cooled in the furnace to obtain a 33 wt% B2O3-10 wt% ZrO2 / γ-Al2O3 catalyst.

[0104] 3. Propane oxidative dehydrogenation activity test

[0105] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal amount of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors).

[0106] The catalytic reaction temperature conditions and reaction results of the 33 wt% B2O3-10 wt% ZrO2 / γ-Al2O3 catalyst in Comparative Example 2 at different catalytic times are summarized in Figure 6 middle.

[0107] Comparative Example 3: Preparation of 33 wt% B2O3-10 wt% ZnO / γ-Al2O3 Catalyst and Performance Test of Propane Oxidative Dehydrogenation

[0108] 1. Preparation of 10 wt% ZnO / γ-Al2O3 Support

[0109] a) Accurately weigh 455.0 mg of zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O, purity ≥99.9%) and dissolve it in 1.0 mL of deionized water. Ultrasonicate for 5 minutes until completely dissolved to prepare a zinc precursor solution.

[0110] b) The above solution was loaded onto 1.0 g of γ-Al2O3 support by the equal volume impregnation method and allowed to stand at room temperature for 12 h;

[0111] c) Dry the sample in a forced air drying oven at 80°C for 12 h;

[0112] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, calcined at this temperature for 2 h, and then cooled in the furnace to obtain a 10 wt% ZnO / γ-Al2O3 support.

[0113] 2. Preparation of 33 wt% B2O3-10 wt% ZnO / γ-Al2O3 Support

[0114] a) Weigh 586.2 mg of boric acid (H3BO3, purity ≥99.5%) and dissolve it in 8.0 mL of 80°C ultrapure water. Stir magnetically (500 rpm) until completely dissolved.

[0115] b) Add 1.0 g of the 10 wt% ZnO / γ-Al2O3 support prepared above and stir in an 80°C water bath (300 rpm) until the solution is completely evaporated;

[0116] c) Dry the sample in a forced air drying oven at 80°C for 12 h;

[0117] d) The temperature was programmed to 550 °C in a muffle furnace at a heating rate of 5 °C / min, calcined at this temperature for 2 h, and then cooled in the furnace to obtain a 33 wt% B2O3-10 wt% ZnO / γ-Al2O3 catalyst.

[0118] 3. Propane Oxidative Dehydrogenation Activity Test

[0119] Catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal amount of quartz sand (60-80 mesh) and loaded into the center of the reactor tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:O2:N2 (volume ratio = 1:1:4) at a total flow rate of 30 mL / min, with nitrogen as the diluent. The reaction mass space velocity (WHSV) was 18,000 mL / (g cat h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The catalytic performance data were as follows: Figure 7 shown.

[0120] The catalytic reaction temperature conditions and reaction results of the 33 wt% B2O3-10 wt% ZnO / γ-Al2O3 catalyst in Comparative Example 3 at different catalytic times are summarized in Figure 7 middle.

Claims

1. A high-stability boron-based catalyst based on rare earth ion bridging anchoring, characterized in that The catalyst comprises a γ-Al2O3 carrier, a rare earth metal oxide intermediate layer sequentially loaded on the carrier, and a B2O3 active component. The rare earth metal is Ce. The loading amount of the rare earth metal oxide in the catalyst is 15-20wt%, and the loading amount of B2O3 is 20-33wt%.

2. A high-stability boron-based catalyst based on rare earth ion bridging anchoring according to claim 1, characterized in that The specific surface area of ​​the γ-Al2O3 is 50-300 m2 / g, and the average pore diameter is 15-25 nm.

3. The method for preparing a high-stability boron-based catalyst based on rare earth ion bridging anchoring according to claim 1, characterized in that The following steps are involved: S1: preparing an aqueous solution of a nitrate of a rare earth metal M, wherein the rare earth metal M is at least one of Gd, Ce, La, and Y, to obtain a solution A; S2: impregnating the γ-Al2O3 support in solution A of step S1, drying after sufficient impregnation, and then transferring to a muffle furnace for high-temperature calcination to obtain a support precursor modified with a rare earth metal M oxide; S3: The precursor of step S2 is immersed in a boric acid aqueous solution, dried after sufficient immersion, and then transferred to a muffle furnace for high-temperature calcination to obtain the final catalyst.

4. The method for preparing a high-stability boron-based catalyst based on rare earth ion bridging anchoring according to claim 3, characterized in that In step S2 or S3, the calcination temperature is 400-700° C., and the calcination time is 1-4 hours.

5. The method for preparing a high-stability boron-based catalyst based on rare earth ion bridging anchoring according to claim 4, characterized in that In step S2 or S3, the calcination temperature is 500-600° C., and the calcination time is 1-3 hours.

6. Use of a high-stability boron-based catalyst based on rare earth ion bridging anchoring as claimed in claim 1 in catalyzing the oxidative dehydrogenation reaction of light alkanes.

7. The use according to claim 6, characterized in that The low carbon alkane is propane, the catalyst is loaded into a fixed bed reactor, the reaction gas is a C3H8-O2-N2 mixed gas with a volume ratio of 1:(0.5-1.5):(1-9), and the reaction gas is passed into the catalyst bed at a catalytic reaction temperature to carry out a catalytic propane oxidative dehydrogenation reaction. The catalytic reaction temperature is 450-550°C, the reaction pressure is atmospheric pressure, and the reaction space velocity is 10000-40000 mL / (g cat ·h).

8. The use according to claim 7, characterized in that The reaction temperature is 520-525 °C, and the reaction space velocity is 15000-20000 mL / (g cat ·h).

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