Ultralow-loading-capacity Ru-based monatomic catalyst, preparation and application thereof in propylene preparation through propane dehydrogenation
By preparing an ultra-low loading Ru-based single-atom catalyst with a Ru-N4 structure, the problems of high cost or environmental unfriendliness of existing catalysts are solved, and efficient propane dehydrogenation is achieved, which has good prospects for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-19
AI Technical Summary
Existing Pt-based and Cr-based propane dehydrogenation catalysts suffer from high cost or environmental inefficiency, and traditional processes are energy-intensive and have high carbon emissions. Therefore, it is necessary to develop low-cost, environmentally friendly, and highly active catalysts.
An ultra-low loading Ru-based single-atom catalyst was prepared by forming a Ru-N4 structure through P and N co-coordination. Ru was highly dispersed in single-atom form on a PNC support. The catalyst was prepared by ball milling and calcination.
It achieves high propane conversion and propylene selectivity, has good catalyst stability, low Ru dosage, and low cost, making it suitable for industrial applications.
Smart Images
Figure CN122057550A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of dehydrogenation catalyst technology, specifically to an ultra-low loading Ru-based single-atom catalyst, its preparation, and its application in propane dehydrogenation to propylene. Background Technology
[0002] Propylene, the second largest olefin after ethylene, is an indispensable key raw material in modern chemical systems. Its downstream derivatives are diverse, mainly including bulk chemicals and fine chemicals such as polypropylene, acrylonitrile, propylene oxide, butanol, and acrylic acid, with applications covering plastics, textiles, rubber, and high-end manufacturing [Chem. Rev., 2014, 114, 10613-10653]. Currently, propylene production mainly includes traditional petroleum catalytic cracking, coal-to-olefins, and propane dehydrogenation. Traditional petroleum processes face problems of raw material shortages and high energy consumption, while coal-to-olefins processes face significant carbon emissions; therefore, with the development and utilization of shale gas, clean and efficient propane dehydrogenation processes have been vigorously developed [Catal. Today, 2005, 106, 103-107].
[0003] Traditional propane dehydrogenation (PDH) catalysts are generally classified into Pt-based (PtSn / Al2O3) and Cr-based catalysts (CrO2). x Two types of propane dehydrogenation catalysts are available: Pt-based catalysts and Cr-based catalysts. Pt-based catalysts can achieve high propylene selectivity, with Pt loading typically at 0.5 wt% or higher. However, Pt is expensive, resulting in high operating costs, and it is prone to agglomeration and sintering under high-temperature reduction conditions, leading to catalyst deactivation. Cr-based catalysts are inexpensive, but Cr metal poses environmental problems, posing higher requirements for the treatment of hazardous waste from subsequent plant operations. Therefore, there is a need to find environmentally friendly, inexpensive, and highly active propane dehydrogenation catalysts.
[0004] Single-atom catalysts, achieving 100% atomic utilization, have been widely applied in thermocatalysis, electrocatalysis, and photocatalysis since their inception. The reaction performance of single-atom catalysts is closely related to the active metal and its coordination structure; therefore, constructing special coordination structures to improve catalyst activity is feasible [Nat. Rev. Chem., 2018, 2, 65-81]. MNC catalysts, as carbon-based catalysts, benefit from high specific surface area, which facilitates the adsorption of reactant molecules, while the weak acidity of carbon itself enhances propylene selectivity. Furthermore, MNC catalysts are easily atomized to construct active centers with different coordination structures, thus possessing the potential to achieve high propane dehydrogenation activity [Angew. Chem. Int. Ed., 2021, 60, 4448]. Ru, with its lower price compared to Pt, has gradually gained attention in recent years. In previous studies, our team prepared a Ru / NC single-atom catalyst with a Ru-N4 active center via ball milling. This catalyst achieved a conversion rate of 13% and a selectivity of 95% at 560 °C [Nat. Catal. 2022, 5, 1145-1156]. However, due to its high Ru metal loading (2 wt%), this catalyst exhibited low intrinsic activity. Based on this, this patent describes a Ru single-atom catalyst with N / P co-coordination, achieving highly efficient propane dehydrogenation while reducing the amount of precious metal required. Summary of the Invention
[0005] The purpose of this invention is to provide an ultra-low loading Ru-based single-atom catalyst, its preparation, and its application in propane dehydrogenation to propylene. This catalyst exhibits high intrinsic activity and selectivity for propane dehydrogenation.
[0006] According to a first aspect of the present invention, an ultra-low loading Ru-based single-atom catalyst is provided, wherein the ultra-low loading Ru-based single-atom catalyst is a supported Ru-based catalyst, and the carbon support is P and N-doped carbon (PNC), wherein the P doping amount is 0.01~10 wt% and the N doping amount is 0.01~30 wt%.
[0007] The Ru content is 0.01~0.2 wt% of the total catalyst mass; Ru is highly dispersed on the support in the form of single atoms. Ru co-coordinates with N and P species to form active centers with a coordination number of 4.
[0008] According to a second aspect of the present invention, a method for preparing an ultra-low loading Ru-based single-atom catalyst is provided, comprising the following steps: Step 1: Dissolve the organic ligand and phosphorus-containing species in 50-200 ml of organic solvent to form a mixed solution. Then add the mixed solution to 30-100 ml of organic solvent containing Ru metal salt. Stir at room temperature for 10-24 h, and then filter and dry to obtain Ru / ZIF-8 precursor. Step 2: The Ru / ZIF-8 precursor obtained in Step 1 is placed in a tube furnace and calcined under an inert atmosphere to obtain an ultra-low loading Ru-based single-atom catalyst.
[0009] Based on the above technical solution, the organic ligands include imidazole, 2-methylimidazolium, zinc nitrate hexahydrate, and zinc acetate.
[0010] Based on the above technical solution, the phosphorus-containing species mentioned in step 1 include triphenylphosphine, phytic acid, phosphoric acid, and sodium hypophosphite.
[0011] Based on the above technical solution, the organic solvent in step 1 is selected from at least one of methanol, anhydrous ethanol, water, and dimethyl sulfoxide.
[0012] Based on the above technical solution, the Ru metal salt in step 1 includes ruthenium acetate, ruthenium nitrate, ruthenium imide nitrate, and ruthenium chloride.
[0013] Based on the above technical solution, in step 1, the mass ratio of organic ligand to phosphorus-containing species is 2~10:1, and the concentration of organic ligand in the mixed solution is 10~50g / L.
[0014] Based on the above technical solution, the concentration of the organic solvent containing Ru metal salt in step 1 is 0.1~10 mg / L.
[0015] Based on the above technical solution, the calcination conditions in step 2 are as follows: The calcination atmosphere includes 10%~100% N2, 10%~100% Ar and 10%~100% He; The calcination temperature is 900~1200℃; The calcination time is 1 to 3 hours.
[0016] According to a third aspect of the present invention, an application of an ultra-low loading Ru-based single-atom catalyst in the dehydrogenation of propane to propylene is provided, specifically: the ultra-low loading Ru-based single-atom catalyst is packed into a fixed-bed tubular reactor, feed gas and balance gas are introduced, and the reaction is carried out to obtain a product containing propylene.
[0017] Based on the above technical solution, the loading amount of the ultra-low loading Ru-based single-atom catalyst is 50~250mg; The composition of the raw material gas is 5~100 vol% C3H8 and 0~20 vol% H2, and the volume ratio of H2 to C3H8 in the raw material gas is 0~1; The balancing gas is an inert gas, specifically N2, He, or Ar. The flow rates of the raw material gas and the balance gas are 10~100 mL / min.
[0018] Based on the above technical solution, the ultra-low loading Ru-based single-atom catalyst also needs to be activated. The specific process is as follows: reduction at 400-600℃ for 0.5-2 hours under a 1-100 vol% H2 / He atmosphere at a gas flow rate of 10-100 mL / min.
[0019] Based on the above technical solution, the ultra-low loading Ru-based single-atom catalyst 10 exhibits good activity, selectivity, and stability within the temperature range of 550~650℃, can operate continuously for more than 50 hours, and has a deactivation rate of less than 0.011 h. -1 .
[0020] Beneficial effects 1. The Ru1 / PNC catalyst prepared by the technical solution disclosed in this invention has highly dispersed Ru and high propane dehydrogenation catalytic activity. With a Ru loading of 0.07 wt%, it can achieve a propane conversion of 15% and a propylene selectivity of 95% at 520℃.
[0021] 2. The Ru1 / PNC catalyst prepared by the technical solution disclosed in this invention promotes the enhancement of propane dehydrogenation activity by anchoring Ru atoms through P and N co-coordination, while inhibiting Ru agglomeration and sintering, thus exhibiting high stability.
[0022] 3. The Ru1 / PNC catalyst prepared by the technical solution disclosed in this invention has an extremely low loading of the noble metal Ru, while the carbon support material is inexpensive and readily available. Compared with industrial PtSn / Al2O3, it is much cheaper and has broad prospects for industrial application. Attached Figure Description
[0023] Figure 1 This is an aberration-corrected scanning transmission electron microscope image of the Ru1 / PNC catalyst from Example 1. Figure 2 EDX mapping diagram of the Ru1 / PNC single-atom catalyst in Example 1; Figure 3 The graph shows a comparison of the specific rates (propylene yield) and propylene selectivity of the Ru1 / PNC single-atom catalyst in Example 1, the Ru1 / NC single-atom catalyst in Comparative Example 1, the Ru1 / NC-BM single-atom catalyst prepared by ball milling in Comparative Example 2, and the commercial PtSn / Al2O3 in Comparative Example 3. Figure 4 The graphs show the reaction activity and propylene selectivity of Ru1 / PNC single-atom catalysts with different loadings as a function of temperature in Examples 1-3. Figure 5 This is a graph showing the reaction activity and propylene selectivity of the Ru1 / PNC single-atom catalyst as a function of temperature in Example 1. Figure 6 The image shows the stability of the Ru1 / PNC single-atom catalyst in Example 1 for propane dehydrogenation at 560°C. Detailed Implementation
[0024] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.
[0025] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.
[0026] In the application example, the conversion rate X of C3H8 C3H8 With C3H6 selective S C3H6 The calculation method is as follows: X C3H8% =([C3H8)) in [C3H8] out ) / [C3H8] in ×100% S C3H6% =[C3H6] out / ([C3H8] in [C3H8] out ) × 100% Among them: [C3H8] in [C3H8] represents the amount of propane in the reaction gas. out [C3H6] out These represent the amounts of propane and propylene in the exported products, respectively.
[0027] The deactivation rate is calculated as follows: Kd(h) 1 ) = (ln((1) X end ) / X end ) ln((1) X start ) / X start )) / t Where: X start and X end t represents the propane conversion rate at the beginning and end of the reaction, respectively, and t represents the stability test time.
[0028] Specific rate calculation method: Specific rate = r / n Ru Where r is the propylene formation rate (mol) C3H6 gcat 1 h 1 ); n Ru This represents the molar amount of Ru contained in the catalyst (mol g). -1 ).
[0029] Example 1: 120 μL of ruthenium nitrite amide was added to 50 mL of methanol and stirred. 2.44 g of zinc nitrate hexahydrate and 1.87 g of triphenylphosphine were added to 150 mL of methanol and stirred until dissolved. 3.08 g of 2-methylimidazole was added to 75 mL of methanol and stirred until dissolved. Then, solutions containing zinc and phosphorus, and solutions containing methylimidazole, were successively added to the Ru-containing methanol solution. The mixture was stirred vigorously at room temperature for 12 h. The solution was then filtered and washed with methanol and dried in a vacuum oven at 60 °C for 24 h. The resulting powder was calcined in a tube furnace at 950 °C for 1 h under an Ar atmosphere. The resulting catalyst was designated as the Ru1 / PNC catalyst. The aberration-corrected scanning transmission electron microscope image of the Ru1 / PNC catalyst is shown below. Figure 1 This indicates that Ru is highly dispersed in single-atom form on the surface of the Ru1 / PNC single-atom catalyst; the EDX mapping image is shown below. Figure 2 This indicates that Ru, P and N elements are uniformly dispersed on the surface of the Ru1 / PNC single-atom catalyst (N doping amount is 9.2wt%, P doping amount is 0.26wt%, and Ru content is 0.07wt%).
[0030] Example 2: 80 μL of ruthenium nitrite amide was added to 50 mL of methanol and stirred. 2.44 g of zinc nitrate hexahydrate and 1.87 g of triphenylphosphine were added to 150 mL of methanol and stirred to dissolve. 3.08 g of 2-methylimidazole was added to 75 mL of methanol and stirred to dissolve. Then, solutions containing zinc and phosphorus and solutions containing methylimidazole were added sequentially to the methanol solution containing Ru. The mixture was stirred vigorously at room temperature for 12 h. Afterward, the mixture was filtered and washed with methanol as the solvent and dried in a vacuum oven at 60 °C for 24 h. The resulting powder was placed in a tube furnace and calcined at 950 °C for 1 h under an Ar atmosphere. The resulting catalyst was designated Ru1 / PNC-80 (N doping amount of 10 wt%, P doping amount of 0.23 wt%, Ru content of 0.03 wt%).
[0031] Example 3: 200 μL of ruthenium nitrite amide was added to 50 mL of methanol and stirred. 2.44 g of zinc nitrate hexahydrate and 1.87 g of triphenylphosphine were added to 150 mL of methanol and stirred to dissolve. 3.08 g of 2-methylimidazole was added to 75 mL of methanol and stirred to dissolve. Then, solutions containing zinc and phosphorus and solutions containing methylimidazole were added sequentially to the methanol solution containing Ru. The mixture was stirred vigorously at room temperature for 12 h. The mixture was then filtered and washed with methanol as the solvent and dried in a vacuum oven at 60 °C for 24 h. The resulting powder was placed in a tube furnace and calcined at 950 °C for 1 h under an Ar atmosphere. The resulting catalyst was designated Ru1 / PNC-200 (N doping amount of 8.9 wt%, P doping amount of 0.3 wt%, Ru content of 0.11 wt%).
[0032] Example 4: 80 μL of ruthenium nitrite amide was added to 50 mL of methanol and stirred. 2.44 g of zinc nitrate hexahydrate and 60 μL of phytic acid were added to 150 mL of methanol and stirred until dissolved. 3.08 g of 2-methylimidazole was added to 75 mL of methanol and stirred until dissolved. Then, solutions containing zinc and phosphorus and solutions containing methylimidazole were added sequentially to the methanol solution containing Ru. The mixture was stirred vigorously at room temperature for 12 h. The mixture was then filtered and washed with methanol as the solvent and dried in a vacuum oven at 60 °C for 24 h. The resulting powder was placed in a tube furnace and calcined at 950 °C for 1 h under an Ar atmosphere (N doping amount: 10 wt%, P doping amount: 0.21 wt%, Ru content: 0.15 wt%).
[0033] Comparative Example 1: 120 μL of ruthenium nitrite amide was added to 50 mL of methanol and stirred. 2.44 g of zinc nitrate hexahydrate was added to 150 mL of methanol and stirred until dissolved. 3.08 g of 2-methylimidazole was added to 75 mL of methanol and stirred until dissolved. Then, solutions containing zinc and phosphorus, and solutions containing methylimidazole, were successively added to the Ru-containing methanol solution. The mixture was stirred vigorously at room temperature for 12 h. The solution was then filtered and washed with methanol and dried in a vacuum oven at 60 °C for 24 h. The resulting powder was placed in a tube furnace and calcined at 950 °C for 1 h under an Ar atmosphere to obtain a P-free Ru1 / NC catalyst. Comparative Example 2: A p-free Ru1 / NC-BM single-atom catalyst was prepared by ball milling, as follows: 20 mg of ruthenium acetylacetone (RuPc), 12 g of dicyandiamine, and 3 g of alanine were weighed and mixed thoroughly, and ball-milled at 400 rpm for 3 h. The mixture was then placed in a tube furnace and pyrolyzed at 600 °C for 1 h under a N2 atmosphere by increasing the temperature at 10 °C / min, followed by pyrolysis at 900 °C for 1 h by increasing the temperature at 2 °C / min, to obtain the target catalyst, denoted as Ru1 / NC-BM.
[0034] Comparative Example 3: A commercial PtSn / Al2O3 catalyst with a Pt loading of 0.5 wt% and a Sn loading of 1.5 wt%.
[0035] Application Example 1: To evaluate the catalytic performance of the prepared catalysts, propane dehydrogenation activity was tested using a fixed-bed reactor. The test conditions were as follows: catalyst (Examples 1-4 and Comparative Examples 1-3) was loaded with 50 mg of catalyst; the feed gas composition was 5% C3H8 and 5% H2 / He, with He as the equilibrium gas; the gas flow rate was 15 ml / min, and the mass hourly space velocity (WHSV) was 18000 ml gcat⁻¹ h⁻¹. Before testing, the catalysts were activated at 600 °C for 30 min under 5% H2 / He conditions. The temperature range for the programmed temperature rise experiment was 500-600 °C, and the stability test temperature was 560 °C. The specific rate was obtained within the kinetic region excluding the influence of internal and external diffusion. The specific rates (propylene yield) and propylene selectivity comparisons of the Ru1 / PNC single-atom catalyst in Example 1, the Ru1 / NC single-atom catalyst in Comparative Example 1, the Ru1 / NC-BM single-atom catalyst prepared by ball milling in Comparative Example 2, and the commercial PtSn / Al₂O₃ in Comparative Example 3 are shown in the figure. Figure 3 This indicates that the Ru1 / PNC single-atom catalyst with N and P co-coordination simultaneously exhibits the highest propylene yield and propylene selectivity; the reaction activity and propylene selectivity of different loadings of Ru1 / PNC single-atom catalysts in Examples 1-3 as a function of temperature are shown in the graphs. Figure 4 This indicates that with increasing Ru loading, the propane conversion of Ru1 / PNC-80, Ru1 / PNC, and Ru1 / PNC-200 single-atom catalysts gradually increases, and all can achieve propylene selectivity of over 90% at 520℃; Example 1 shows the reaction activity and propylene selectivity of the Ru1 / PNC single-atom catalyst as a function of temperature. Figure 5 This indicates that with increasing temperature, the propane conversion rate of the Ru1 / PNC single-atom catalyst increases from 12% at 500℃ to 28% at 600℃, while the propane selectivity remains above 91%. The stability diagram of the Ru1 / PNC single-atom catalyst for propane dehydrogenation at 560℃ in Example 1 is shown below. Figure 6 This indicates that the Ru1 / PNC single-atom catalyst maintains high stability at 560℃, with a deactivation rate of only 0.011 h within 50 h. -1 .
[0036] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A Ru-based single-atom catalyst with ultra-low loading, characterized in that, The ultra-low loading Ru-based single-atom catalyst is a supported Ru-based catalyst with Ru as the active component and P and N-doped carbon as the carbon support, wherein the P doping amount is 0.01~10wt% and the N doping amount is 0.01~30wt%. The Ru content is 0.01~0.2 wt% of the total catalyst mass; Ru is highly dispersed on the support in the form of single atoms. Ru co-coordinates with N and P species to form active centers with a coordination number of 4.
2. A method for preparing an ultra-low loading Ru-based single-atom catalyst, characterized in that, Includes the following steps: Step 1: Dissolve the organic ligand and phosphorus-containing species in 50-200 ml of organic solvent to form a mixed solution. Then add the mixed solution to 30-100 ml of organic solvent containing Ru metal salt. Stir at room temperature for 10-24 h, and then filter and dry to obtain Ru / ZIF-8 precursor. Step 2: The Ru / ZIF-8 precursor obtained in Step 1 is placed in a tube furnace and calcined under an inert atmosphere to obtain an ultra-low loading Ru-based single-atom catalyst.
3. The preparation method according to claim 2, characterized in that, The organic ligands mentioned in step 1 include imidazole, 2-methylimidazolium, zinc nitrate hexahydrate, and zinc acetate; The phosphorus-containing species mentioned in step 1 include triphenylphosphine, phytic acid, phosphoric acid, and sodium hypophosphite; The organic solvent mentioned in step 1 is selected from at least one of methanol, anhydrous ethanol, water, and dimethyl sulfoxide; The Ru metal salts mentioned in step 1 include ruthenium acetate, ruthenium nitrate, ruthenium imide nitrate, and ruthenium chloride.
4. The preparation method according to claim 2, characterized in that, In step 1, the mass ratio of organic ligand to phosphorus-containing species is 2~10:1, and the concentration of organic ligand in the mixed solution is 10~50 g / L.
5. The preparation method according to claim 2, characterized in that, The concentration of the organic solvent containing the Ru metal salt in step 1 is 0.1~10 mg / L.
6. The preparation method according to claim 2, characterized in that, The calcination conditions described in step 2 are as follows: The calcination atmosphere includes 10%~100% N2, 10%~100% Ar and 10%~100% He; The calcination temperature is 900~1200℃; The calcination time is 1 to 3 hours.
7. The application of an ultra-low loading Ru-based single-atom catalyst in propane dehydrogenation to propylene, characterized in that, Specifically, an ultra-low loading Ru-based single-atom catalyst is packed into a fixed-bed tubular reactor, and feed gas and balance gas are introduced. The reaction is carried out at 500~600℃ to obtain a product containing propylene.
8. The application according to claim 7, characterized in that, The loading amount of the ultra-low loading Ru-based single-atom catalyst is 50~250 mg; The composition of the raw material gas is 5~100 vol% C3H8 and 0~20 vol% H2; The balancing gas is an inert gas, specifically N2, He, or Ar. The flow rates of the raw material gas and the balance gas are 10~100 mL / min.
9. The application according to claim 7, characterized in that, The ultra-low loading Ru-based single-atom catalyst also needs to be activated. The specific process is as follows: reduction at 400-600℃ for 0.5-2 hours under a 1-100 vol% H2 / He atmosphere at a gas flow rate of 10-100 mL / min.