A method for preparing a ruthenium-grafted manganese-aluminum hydrotalcite and catalyzing hydrogenation of co2 to form formic acid
The RuMnAl-LDH catalyst was prepared by co-precipitation and used to catalyze the hydrogenation of CO2 to formic acid under optimized reaction conditions. This solved the problems of poor catalyst separation and stability in the existing technology, realizing the potential for efficient formic acid production and industrial application of the catalyst.
Patent Information
- Application Number
- CN202510059679.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-15
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2045-01-15
AI Technical Summary
Existing homogeneous catalysts suffer from difficulties in catalyst separation and recovery and poor stability during the hydrogenation of CO2 to formic acid. Heterogeneous catalyst support materials are expensive and have complex synthesis routes, which limits their industrial application.
RuMnAl-LDH catalyst was prepared by coprecipitation and activated in a muffle furnace to obtain RuMnAl hydrotalcite. As a heterogeneous catalyst, it was used to catalyze the hydrogenation of CO2 to formic acid under optimized reaction conditions. A methanol:water mixture was used as the solvent, the total pressure was 60 bar, and the reaction was carried out at 60℃ for 24 hours, achieving high catalytic activity and stability.
Under optimized conditions, the conversion number (TON) of formic acid reaches over 8000. The catalyst preparation process is simple, the raw materials are readily available, and it exhibits good catalytic activity and stability, making it suitable for industrial production.
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Figure CN119869524B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically a ruthenium-grafted manganese aluminum hydrotalcite and a method for catalytically hydrogenating CO2 to formic acid. Background Technology
[0002] CO2, a potent greenhouse gas, is a major contributor to global warming. Converting CO2 into useful chemicals can reduce or suppress CO2 emissions while generating added value, representing a promising green process for CO2 treatment. Formic acid has indispensable applications in numerous fields, including textiles, dyeing, pharmaceuticals, and perfumes, and plays a crucial role in chemical synthesis and hydrogen storage and transportation. Catalytic hydrogenation of CO2 to formic acid can effectively mitigate the greenhouse effect and climate problems caused by CO2 emissions, while also producing high-value-added formic acid products, offering both environmental and economic benefits. A high-performance catalyst is the core factor in the production of formic acid from CO2 hydrogenation. Catalysts used for CO2 hydrogenation to formic acid include homogeneous and heterogeneous catalysts. Homogeneous catalysts, primarily composed of transition metal complexes, exhibit fast reaction rates and high catalytic activity, but suffer from drawbacks such as difficulty in catalyst separation and recovery, and poor catalytic stability, limiting their further industrial applications. In contrast, heterogeneous catalysts are easier to separate and recover, and exhibit better stability. Therefore, the design of catalysts for the catalytic hydrogenation of CO2 to formic acid increasingly focuses on heterogeneous catalytic systems. The construction of heterogeneous catalysts usually requires a support, and the selection of a high-performance support is of great significance for improving catalytic activity and selectivity.
[0003] Hydrotalcite is a type of layered bimetallic hydroxide that is simple to prepare and readily grafts metals. Its catalytic performance can be optimized through methods such as anionic intercalation and adjusting the metal molar ratio, and it is commonly used to construct heterogeneous catalysts. For example, CN116174034 A uses a homogeneous precipitation method to prepare CaZnAl-based hydrotalcite as a catalyst precursor, followed by high-temperature calcination to obtain a CaZnAl-O solid base, which is then used to catalyze the synthesis of dodecyl alcohol esters. Catalysts2022,12,759 uses the organic base tetramethylammonium hydroxide (TMAH) to design and synthesize a MgZnAl-LDH type material for catalyzing Clayson-Schmidt condensation.
[0004] However, most support materials suffer from high costs and complex synthesis routes, hindering their industrial production. Hydrotalcite, on the other hand, is low-cost, widely available, and easily grafted with metals. Using hydrotalcite as a support material to graft Ru metal provides a simple, convenient, and low-cost method for synthesizing heterogeneous catalysts for the hydrogenation of CO2 to formic acid. Summary of the Invention
[0005] The purpose of this invention is to provide a ruthenium-grafted manganese aluminum hydrotalcite and a method for catalytically hydrogenating CO2 to produce formic acid in order to solve the problems mentioned above.
[0006] The technical solution adopted in this invention is as follows: Under optimized reaction conditions, using a methanol:water mixture as solvent (5:1, v / v), a total pressure of 60 bar, 60°C, and a reaction time of 24 hours, the formic acid conversion number (TON) reaches over 8000.
[0007] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite, comprising the following steps:
[0008] S1: Mix RuCl3·xH2O, Mn(NO3)2, and Al(NO3)3·9H2O according to the following ratio: Ru:Mn:Al=
[0009] A mixed salt solution is obtained by dissolving a salt in deionized water at a molar ratio of (0.5-2):(50-200):20.
[0010] S2: Add dropwise to a 1.6M NaNO3 solution and stir continuously for about 45 minutes;
[0011] S3: Use 1M NaOH solution to maintain a constant pH of 10;
[0012] S4: Transfer the obtained mixture to a stainless steel autoclave coated with polytetrafluoroethylene, age it at 80°C for 16 hours, then filter and wash it.
[0013] S5: The solid material was dried at 80°C, ground and vacuum stored to obtain RuMnAl-type hydrotalcite solid powder, and then activated in a muffle furnace at 500°C for 4 hours to obtain RuMnAl-LDH heterogeneous catalyst;
[0014] S6: Charge the reactor with an appropriate amount of catalyst, a mixed solution of methanol and deionized water, rinse the reactor three times with CO2 to remove air, then introduce CO2 / H2 (1:1, p / p) to a suitable pressure and raise the temperature to start the reaction;
[0015] S7: After the reaction is complete, the product is collected to obtain the prepared formic acid, and then the entire process of ruthenium-grafted manganese aluminum hydrotalcite and catalytic CO2 hydrogenation to produce formic acid can be completed.
[0016] In a preferred embodiment, in step S1, the molar ratio of Ru, Mn, and Al is 1:100:28.
[0017] In a preferred embodiment, in step S6, the volume ratio of methanol to deionized water used in the 100ml autoclave is 5:1, and the amount of catalyst used is 60-100mg.
[0018] In a preferred embodiment, in step S6, the volume ratio of methanol to deionized water used in the 100ml autoclave is 5:1, and the catalyst dosage is 90mg.
[0019] In a preferred embodiment, in step S6, the reaction temperature is 60°C during the process of introducing CO2 / H2 (1:1, p / p) to a suitable pressure and then raising the temperature to start the reaction.
[0020] In a preferred embodiment, in step S6, the stirring rate is 800 rpm during the process of introducing CO2 / H2 (1:1, p / p) to a suitable pressure and then heating to start the reaction.
[0021] In a preferred embodiment, in step S6, after CO2 / H2 (1:1, p / p) is introduced to a suitable pressure and the temperature is increased to start the reaction, the final pressure is pCO2 = 30 bar and pH2 = 30 bar.
[0022] In a preferred embodiment, the RuMnAl-LDH catalyst is used in the catalytic hydrogenation of CO2 to formic acid, where the hydrogenation of carbon dioxide requires a reaction under high pressure and high temperature. A 100 mL autoclave is used. All operations involving gas injection are performed in a well-ventilated fume hood. The specific steps are as follows:
[0023] A certain amount of catalyst, methanol, and deionized water solution mixed in the required volume ratio are charged into the reactor.
[0024] The container was sealed, and the reactor was flushed three times with CO2 to remove air. Then it was pressurized with CO2 / H2 (1:1, p / p) to the final desired total pressure (p / p).
[0025] Use a temperature controller to heat the reactor to the required temperature. When the internal temperature of the reactor reaches the specified temperature, start stirring at a fixed stirring speed (200-800 rpm), which is considered the start of the reaction.
[0026] After the required reaction time, stop stirring and heating, and allow the reactor to cool to room temperature.
[0027] The reactor is depressurized at room temperature, the container is opened, and the reaction solution is collected by simple filtration to separate the catalyst.
[0028] High performance liquid chromatography (HPLC) was used to analyze the hydrogenation products, and the concentration of the hydrogenation products was determined by a standard calibration curve plotted at a wavelength of 190 nm, which was composed of area and formic acid concentration.
[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0030] In this invention, under optimized reaction conditions, using a methanol:water mixture as the solvent (5:1), a total pressure of 60 bar, and a reaction temperature of 60°C for 24 hours, the formic acid conversion number (TON) reached over 8000. RuMnAl-LDH was prepared using a co-precipitation method, and the RuMnAl hydrotalcite catalyst was obtained by activation in a muffle furnace. The preparation process is simple, and the raw materials are readily available. The RuMnAl-LDH catalyst prepared in this invention exhibits good catalytic activity and stability in the catalytic hydrogenation of formic acid to formic acid, and has broad application prospects. Attached Figure Description
[0031] Figure 1 This is a schematic diagram illustrating the process principle of the present invention;
[0032] Figure 2 This is a SEM image of the RuMnAl-LDH catalyst used in this invention. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0034] Reference Figure 1-2 ,
[0035] Example 1:
[0036] The preparation of a RuMnAl-LDH catalyst includes the following steps:
[0037] (1) Preparation of solution A: Dissolve 6.8g of NaNO3 in 50ml of deionized water to obtain a 1.6M NaNO3 solution for later use. Solution B is a mixed salt solution obtained by dissolving RuCl3·xH2O, Mn(NO3)2 and Al(NO3)3·9H2O in deionized water at a certain molar ratio.
[0038] (2) Prepare solution B: Mix 0.1g RuCl3·xH2O, 9g Mn(NO3)2, and 3.5g Al(NO3)3·9H2O and dissolve them in 50ml of deionized water.
[0039] (3) Add solution B dropwise to solution A at room temperature and stir continuously for about 45 minutes. Use 1M NaOH solution to keep the pH constant at 10.
[0040] (4) Transfer the obtained mixture to a stainless steel autoclave coated with polytetrafluoroethylene and age it at 80°C for 16 hours.
[0041] (5) The precipitate is filtered and washed with hot distilled water to remove unreacted ions.
[0042] (6) The solid material obtained in step (5) is dried at 80°C in a vacuum drying oven, ground and then vacuum preserved to obtain RuMnAl hydrotalcite solid powder.
[0043] (7) The solid powder obtained in step (6) was activated in a muffle furnace at 500°C for 4 hours to obtain RuMnAl hydrotalcite catalyst.
[0044] Example 2:
[0045] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite includes the following steps:
[0046] (1) Inject a mixture of 60 mg catalyst, 10 ml methanol and 1 ml deionized water into a high-pressure reactor.
[0047] (2) Seal the container, rinse the reactor three times with CO2 to remove air, and then pressurize it with CO2 / H2 (1:1, p / p) to pCO2 = 30 bar and pH2 = 30 bar.
[0048] (3) Heat the reactor to 60°C using a temperature controller. When the internal temperature of the reactor reaches the specified temperature, start stirring at 800 rpm to mark the start of the reaction.
[0049] (4) After the required reaction time, stop stirring and heating, and allow the reactor to cool to room temperature.
[0050] (5) The reactor is depressurized at room temperature, the container is opened, and the reaction solution is collected by simple filtration to separate the catalyst.
[0051] (6) The hydrogenation products were analyzed by high performance liquid chromatography, and the concentration of the hydrogenation products was determined by a standard calibration curve plotted by area and formic acid concentration at a wavelength of 190 nm.
[0052] Example 3:
[0053] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite is disclosed. The difference between this method and Example 2 is the amount of catalyst used. In this example, the amount of catalyst used is 70 mg, while the rest is the same as in Example 2. Catalytic experiments were conducted.
[0054] Example 4:
[0055] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite is disclosed. The difference between this method and Example 2 is the amount of catalyst used. In this example, the amount of catalyst used is 80 mg, while the rest is the same as in Example 2. Catalytic experiments were conducted.
[0056] Example 5:
[0057] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite is disclosed. The difference between this method and Example 2 is the amount of catalyst used. In this example, the amount of catalyst used is 90 mg, while the rest is the same as in Example 2. Catalytic experiments were conducted.
[0058] Example 6:
[0059] A method for producing formic acid by catalytic hydrogenation of CO2 using ruthenium-grafted manganese aluminum hydrotalcite is disclosed. The difference between this method and Example 2 is the amount of catalyst used. In this example, the amount of catalyst used is 100 mg, while the rest is the same as in Example 2. Catalytic experiments were conducted.
[0060] The formic acid yields of Examples 2 to 6 are shown in Table 1 below:
[0061]
[0062] As shown in Table 1, the formic acid formation rate was highest when the catalyst dosage was 90 mg and 100 mg. Therefore, Example 5, which used less catalyst, was selected for the cycle stability test. See Example 7 for details.
[0063] Example 7: Recovery and recycling of a RuMnAl-LDH catalyst after primary catalytic CO2 hydrogenation to formic acid, the steps are as follows:
[0064] (1) Separate the catalyst that was catalyzed in Example 5, wash it with deionized water and dry it at 80°C.
[0065] (2) The dried catalyst was used to catalyze the hydrogenation of CO2 to produce formic acid, and the operation steps were the same as in Example 2.
[0066] (3) The formic acid formation rate was measured and recorded for each recycling cycle, as shown in Table 2.
[0067]
[0068] From the above experimental results, we can conclude that:
[0069] In this invention, under optimized reaction conditions, using a methanol:water mixture as the solvent (5:1), a total pressure of 60 bar, and a reaction temperature of 60°C for 24 hours, the formic acid conversion number (TON) reached over 8000. RuMnAl-LDH was prepared using a co-precipitation method, and the RuMnAl hydrotalcite catalyst was obtained by activation in a muffle furnace. The preparation process is simple, and the raw materials are readily available. The RuMnAl-LDH catalyst prepared in this invention exhibits good catalytic activity and stability in the catalytic hydrogenation of formic acid to formic acid, and has broad application prospects.
[0070] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0071] The foregoing description enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a ruthenium-grafted manganese-aluminum hydrotalcite catalyst, characterized in that: The process includes the following steps: S1: A mixed salt solution obtained by dissolving RuCl3·xH2O, Mn(NO3)2 and Al(NO3)3·9H2O in deionized water at a molar ratio of Ru:Mn:Al = (0.5-2):(50-200):20; S2: Add dropwise to a 1.6M NaNO3 solution and stir continuously for about 45 minutes; S3: Use 1M NaOH solution to maintain a constant pH of 10; S4: Transfer the obtained mixture to a stainless steel autoclave coated with polytetrafluoroethylene, age it at 80°C for 16 hours, then filter and wash it. S5: The solid material was dried at 80°C, ground, and vacuum preserved to obtain RuMnAl-type hydrotalcite solid powder, which was then activated in a muffle furnace at 500°C for 4 hours to obtain RuMnAl-LDH heterogeneous catalyst.
2. The preparation method of the ruthenium-grafted manganese aluminum hydrotalcite catalyst as described in claim 1, characterized in that: In step S1, the molar ratio of Ru, Mn, and Al is 1:100:
28.
3. An application of a ruthenium-grafted manganese-aluminum hydrotalcite catalyst in the catalytic hydrogenation of CO2 to formic acid, characterized in that, The catalyst is prepared using the preparation method described in claim 1, and its application includes the following steps: SS1: A suitable amount of catalyst, a mixed solution of methanol and deionized water is charged into the reactor. After the reactor is flushed three times with CO2 to remove air, CO2 and H2 with a pressure ratio of 1:1 are introduced. After reaching a suitable pressure, the temperature is raised to start the reaction. SS2: After the reaction is complete, the product is collected to obtain the prepared formic acid, and then the entire process of ruthenium-grafted manganese aluminum hydrotalcite and catalytic CO2 hydrogenation to produce formic acid is completed.
4. The application of the ruthenium-grafted manganese-aluminum hydrotalcite catalyst as described in claim 3 for the catalytic hydrogenation of CO2 to formic acid, characterized in that: In step SS1, a 100ml autoclave is used with a methanol to deionized water volume ratio of 5:1 and a catalyst dosage of 90mg.
5. The application of the ruthenium-grafted manganese-aluminum hydrotalcite catalyst as described in claim 3 for the catalytic hydrogenation of CO2 to formic acid, characterized in that: In step SS1, the reaction temperature is 60°C and the stirring speed is 800 rpm during the process of introducing CO2 and H2 at a pressure ratio of 1:1 to a suitable pressure and then raising the temperature to start the reaction.
6. The application of the ruthenium-grafted manganese-aluminum hydrotalcite catalyst as described in claim 3 for the catalytic hydrogenation of CO2 to formic acid, characterized in that: In step SS1, CO2 and H2 with a pressure ratio of 1:1 are introduced, and the final pressure is pCO2=30 bar and pH2=30 bar.
7. The application of the ruthenium-grafted manganese-aluminum hydrotalcite catalyst as described in claim 3 for the catalytic hydrogenation of CO2 to formic acid, characterized in that: In step SS2, the specific steps are as follows: (1) After the required reaction time, stop stirring and heating, and allow the reactor to cool to room temperature; (2) The reactor is depressurized at room temperature, the container is opened, and the reaction solution is collected by simple filtration to separate the catalyst; (3) The hydrogenation products were analyzed by high performance liquid chromatography, and the concentration of the hydrogenation products was determined by a standard calibration curve plotted by area and formic acid concentration at a wavelength of 190 nm.