A surface aminated Ru-REUSY molecular sieve catalyst and its preparation method and application

Abstract

The present invention provides a surface-aminated Ru-REUSY molecular sieve catalyst, its preparation method, and application, belonging to the field of catalyst preparation. The preparation method of the surface-aminated Ru-REUSY molecular sieve catalyst comprises: dealuminating a commercial-grade carrier REUSY molecular sieve, mixing and calcining a RuCl3·3H2O solution with the dealuminated carrier, and finally adding an aminating agent for surface amination. The present invention adopts Ru-modified REUSY molecular sieve, which is applied to catalyze the reaction of glycerol reducing carbon dioxide, realizing the conversion of carbon dioxide into formic acid while glycerol is converted into lactic acid; the conversion of carbon dioxide not only alleviates the greenhouse effect but also effectively utilizes carbon resources; glycerol, as a reducing agent, makes the reaction mild and is the key to reducing the cost of biodiesel and supporting the sustainable development of biodiesel.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, in particular to a surface aminated Ru-REUSY molecular sieve catalyst and a preparation method and application thereof. Background Art

[0002] Climate change is a major environmental concern worldwide. Carbon dioxide (CO2), a greenhouse gas, primarily originates from the combustion of fossil fuels. Converting CO2 into high-value carbon compounds would not only alleviate environmental concerns but also effectively utilize one of the most abundant and inexpensive carbon resources. Therefore, research on the sequestration and recycling of CO2 has garnered widespread attention worldwide.

[0003] However, CO2 is highly inert and difficult to activate, and the reduction process often requires high energy and electron donors, such as the reducing agent H2, carbon anions, or external energy sources. Therefore, catalytic hydrogenation has become a core research direction in this field. Traditional catalytic hydrogenation of CO2 requires a large supply of hydrogen, and industrial hydrogen production mostly comes from cracked petroleum gas. Therefore, finding a cheap, readily available, and naturally abundant reducing agent to efficiently reduce CO2 has become a hot topic and a challenge.

[0004] Research has shown that by leveraging glycerol's ability to reduce water to produce hydrogen under hydrothermal alkaline catalysis, CO2 can be reduced to formic acid while maintaining efficient conversion to lactic acid. In this reaction, glycerol is the primary byproduct of biodiesel production, yielding 1 kg of crude glycerol for every 10 kg of biodiesel produced. Meanwhile, the rapid growth of global biodiesel production has led to an oversupply in the glycerol market, resulting in a significant drop in glycerol prices.

[0005] Therefore, using certain technologies to increase the added value of glycerol can not only solve the problem of glycerol oversupply and waste, but also reduce the production cost of biodiesel and promote the development of renewable energy. Using glycerol as a reducing agent not only fully utilizes its polyhydroxyl chemical properties but also makes the reduction process more sustainable. Lactic acid is not only a precursor for the synthesis of important chemical raw materials but can also be used to produce biodegradable lactic acid polymers. Furthermore, formates are widely used in various industrial processes and play an important role in our daily lives.

[0006] Current research indicates that homogeneous catalytic CO₂ hydrogenation to formic acid has achieved impressive results, offering advantages such as rapid reaction speed, high selectivity, and high metal utilization. However, the difficulty in separating, recovering, and reusing the catalyst after the reaction hinders its industrial application. Consequently, research is shifting towards heterogeneous catalysts.

[0007] Catalysts for the heterogeneous conversion of carbon dioxide to formic acid fall into two main categories: alloy catalysts and metal-supported catalysts. Research progress in the hydrogenation of carbon dioxide to formic acid has shown that transition metal complexes and Group VIII transition metals are predominant, with Ru and Rh being particularly effective. Furthermore, organic solvents, weakly basic metal salts, and alcohols are often added to the system to increase the yield of formic acid (salt).

[0008] CN108409551A discloses a method for reducing carbon dioxide using Ru-MACHO-catalyzed glycerol. The catalyst used in this method is a ruthenium chelate Ru-MACHO (regR), provided by Tokyo Chemical Industry Co., Ltd. (TCI). This catalyst is relatively expensive, requiring significant investment for industrial application, and the chelate's mechanism of action on the substrate is complex. Furthermore, the patent reports a formic acid yield of 36.77% at 200°C for 24 hours using a dosage of 0.33M glycerol, 3.0mg Ru-MACHO, and 7.92g KHCO₃. This indicates relatively low acid production efficiency.

[0009] Therefore, based on the above considerations, the purpose of this study is to develop and prepare suitable heterogeneous Ru catalysts to improve the efficiency of carbon dioxide hydrogenation to produce formic acid and glycerol to produce lactic acid. Summary of the Invention

[0010] To address the aforementioned issues in the prior art, the present invention provides a surface-aminated Ru-REUSY molecular sieve catalyst, its preparation method, and its application. This invention utilizes Ru-modified REUSY molecular sieves to catalyze the reduction of carbon dioxide by glycerol, converting carbon dioxide to formic acid and glycerol to lactic acid simultaneously. The conversion of carbon dioxide mitigates the greenhouse effect and effectively utilizes carbon resources. Glycerol, acting as a reducing agent, moderates the reaction and is key to reducing the cost of biodiesel and supporting its sustainable development.

[0011] The technical solutions of the present invention are as follows:

[0012] The present invention first provides a surface aminated Ru-REUSY molecular sieve catalyst, and the preparation method of the molecular sieve catalyst comprises the following steps:

[0013] (1) Pour commercial-grade carrier REUSY molecular sieve and concentrated nitric acid into a container, maintain the temperature at 70-90°C, and stir at a rate of 200-300 rpm for 3-20 hours to carry out dealumination; the mass volume ratio of the carrier REUSY molecular sieve to concentrated nitric acid is 5-10g:100-200ml;

[0014] The dealuminated mixture was centrifuged at 2500-3500 rpm and then washed with deionized water until the pH of the washing solution was neutral. The washed solid was dried to obtain the dealuminated support deAl-REUSY, which was used as the matrix for the liquid impregnation method.

[0015] (2) preparing a RuCl3·3H2O solution having a concentration in the range of 2 wt.% to 30 wt.%, taking 1 g of the dealuminated support deAl-REUSY obtained in step (1) and suspending it in the RuCl3 solution to obtain a mixture of ruthenium and molecular sieve;

[0016] The mixture was ultrasonicated in an ultrasonic machine for 30-40 minutes, allowed to stand and dried after mixing evenly; and then calcined in a tube furnace at 550-565° C. under air conditions for 5-6 hours to obtain a ruthenium-supported catalyst Ru-REUSY;

[0017] (3) performing surface amination: pouring ethanol into a container, dispersing the Ru-REUSY catalyst obtained in step (2) in the ethanol solution; the mass volume ratio of the Ru-REUSY catalyst to ethanol is 0.5-1 g: 250-2500 ml;

[0018] Then, the amination reagent was added and the round-bottom flask was stirred at 150-250 rpm in an oil bath at 75-85°C for 4-6 hours; the mass volume ratio of the Ru-REUSY catalyst to the amination reagent was 0.5-1 g: 50-200 μL;

[0019] Finally, the mixture of the product obtained after stirring is cooled to room temperature and washed with a large amount of ethanol, and then dried to obtain an amination catalyst.

[0020] Preferably, the concentration of the concentrated nitric acid in step (1) is 65.0-68.0%; the drying method is to first dry the washed solid at 105-110°C for 1.5-2.5 hours to remove moisture, and then dry it at 150-160°C for 10-12 hours to remove inorganic impurities.

[0021] Preferably, the standing time in step (2) is 10-12 hours, and the drying is performed at 115-125° C. for 10-12 hours.

[0022] Preferably, the loaded metal Ru in step (2) is replaced by any one of Rh, Re, Cr, Mo, W, Pd, Cu, Fe, Sn, Pb, and In.

[0023] Preferably, the amination reagent in step (3) is any one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-aminoethyl-3-aminopropyltrimethoxysilane, and N-aminoethyl-3-aminopropylmethyldimethoxysilane;

[0024] The drying step is to dry the mixture in a non-sealed container at 80-85° C. for 10-12 hours.

[0025] The present invention also provides an application of the surface aminated Ru-REUSY molecular sieve catalyst, which is used to catalyze glycerol to reduce carbon dioxide to formic acid. The specific steps of the application include:

[0026] S1. Stirring the glycerol solution, carbon dioxide source, base, and surface aminated Ru-REUSY molecular sieve catalyst in a reactor;

[0027] S2. Then fix the reactor on the rotating shaft of the rotary oven, heat it to 150-200°C, and keep it for 24-36 hours;

[0028] S3. After the set reaction time, quickly transfer to an ice water bath and cool to 25°C.

[0029] Preferably, the ratio of the carbon dioxide source to glycerol is in the range of 2.64-10.56 g:6.6 mmol; the ratio of the surface aminated Ru-REUSY molecular sieve catalyst addition to glycerol is in the range of 0.02-0.2 g:6.6 mmol; and the ratio of the base addition to glycerol is in the range of 2.22-6.66 g:6.6 mmol.

[0030] Preferably, the carbon dioxide source includes but is not limited to alkali metal carbonates, alkaline earth metal carbonates, subgroup metal carbonates, alkali metal bicarbonates, ammonium carbonate or dry ice.

[0031] Preferably, the base includes but is not limited to KOH and NaOH.

[0032] Preferably, the glycerol solution is an aqueous solution of glycerol, and its concentration range is 0.33-2.67 mol / L.

[0033] The beneficial technical effects of the present invention are:

[0034] 1. The inventors discovered that molecular sieves alone or dealuminated molecular sieves did not promote the formation of carbon dioxide in the glycerol-catalyzed reaction. Furthermore, the use of metal alone had little effect on the yield of the reaction. After extensive experiments, they ultimately found that loading the metal Ru onto the molecular sieve resulted in a significant increase in yield. Furthermore, different molecular sieves exhibited different stability in different reaction systems. Through multiple screening and comparison, the inventors determined that REUSY molecular sieve was the most effective for the reaction system and ultimately selected it.

[0035] 2. The catalyst support, REUSY molecular sieve, selected in this invention, enhances catalytic performance through its inherent properties and its interaction with the active components. This interaction refers to the following effects: metal loading onto the molecular sieve alters the catalyst's morphology and structure, dispersing and supporting the catalyst, thereby increasing the catalyst's specific surface area; and provides high mechanical strength and thermal stability, as well as stability to acids, bases, and organic solvents, improving reusability.

[0036] 3. The present invention uses dry ice as a solid carbon dioxide source. This inexpensive and widely available solid carbon dioxide easily evaporates and sublimates into non-toxic, odorless gaseous carbon dioxide, which is 600-800 times larger in volume than its solid form. When glycerol is used to catalyze the reduction of carbon dioxide (dry ice), the high pressure generated by the substantial expansion of dry ice during sublimation, as well as the alkalinity it provides, significantly increases the amount of carbon dioxide available for the reaction compared to KHCO3.

[0037] 4. The present invention prepares a relatively inexpensive catalyst by modifying molecular sieves in the laboratory and loading them with metals. Under the reaction conditions of 6.6 mmol glycerol, 3.48 g CO2, 4.44 g KOH, and 0.10 g catalyst, at 200°C for 24 hours, a formic acid yield of 57.31% and a lactic acid yield of 18.38% were achieved, which is a significant improvement over the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the effect of different dealumination times on the catalyst, where LA is the abbreviation for lactic acid and FA is the abbreviation for formic acid.

[0039] Figure 2 is the XRD spectrum of different Ru loading amounts.

[0040] Figure 3 This is the XPS spectrum of Ru-deAl(5h)-REUSY with a Ru loading of 15 wt%.

[0041] Figure 4 Schematic diagram of the effect of different Ru loading amounts on the catalytic performance of deAl(3 / 5h / 10h)-REUSY.

[0042] Figure 5This is a schematic diagram of the effect of different reaction times on the catalytic performance of 10wt.%Ru-deAl(3 / 5h / 10h)-REUSY.

[0043] Figure 6 This is a schematic diagram of the effect of different reaction temperatures on the catalytic performance of 10wt.%Ru-deAl(5h)-REUSY.

[0044] Figure 7 This is the XRD spectrum of Ru-REUSY after recovery.

[0045] Figure 8 This is a schematic diagram comparing the catalytic activity of Ru catalysts supported on different carriers.

[0046] Figure 9 are the XRD spectra of different carriers. DETAILED DESCRIPTION

[0047] The present invention is described in detail below with reference to the accompanying drawings and embodiments. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, rather than all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0048] When the catalytic reaction is completed, the mixture is quickly transferred to an ice water bath and cooled to 25°C. The reaction effect is tested by adjusting the pH value of the reaction solution to 6-7 using a 0.10 mol / L dilute hydrochloric acid solution, filtering the solution through a 0.45 μm aqueous phase needle filter, and diluting the solution 10 times with deionized water before analyzing the solution using high performance liquid chromatography (HPLC) equipped with a UV detector and a differential detector. The specific method is as follows:

[0049] Formic acid and lactic acid were analyzed using an ultraviolet detector (HPLC-UV, Agilent 1200) at a wavelength of 210 nm, and glycerol was analyzed using a differential refractive index detector (HPLC-RI, Agilent 1200). The detector temperature was set to 45°C, and an Aminex HPX-87H (7.8 mm × 300 mm) chromatographic column was selected. The mobile phase was a 0.50% volume fraction H2SO4 solution at a flow rate of 0.50 mL / min and a column temperature of 55°C.

[0050] Example 1:

[0051] This embodiment provides a method for preparing Ru-REUSY molecular sieve that has not been surface aminated and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid.

[0052] (1) The specific steps of the preparation method of Ru-REUSY molecular sieve are as follows:

[0053] (1) 5 g of commercial-grade carrier REUSY molecular sieve and 100 mL of concentrated nitric acid were poured into a flask and stirred at 200 rpm in a water bath at 80°C for 3 h, 5 h, 10 h, and 20 h for dealumination.

[0054] The dealuminated mixture was centrifuged at 2500-3500 rpm and then washed with deionized water 6-7 times until the pH of the wash solution was neutral. The washed solid was then dried at 105°C for 2 hours to remove moisture and then at 150°C for 10 hours to remove inorganic impurities, yielding the deAl-REUSY support.

[0055] (2) RuCl3·3H2O was prepared into a solution with a concentration of 10%, and 0.1 g of the catalyst was suspended in the RuCl3 solution to prepare a mixture with a loading of 10 wt.%.

[0056] (3) The mixture was sonicated in an ultrasonic machine for 30 minutes, allowed to stand for 12 hours after uniform mixing, and then dried in an oven at 120°C for 12 hours. Finally, it was calcined in air at 550°C in a tube furnace for 6 hours to obtain a 10 wt.% Ru-deAl-REUSY catalyst.

[0057] (II) Application of the prepared supported catalyst:

[0058] 20 mL of glycerol solution (0.33 M) and 7.92 g of KHCO3 were used as reaction substrates, 0.1 g of catalyst was added to each, and the reaction was carried out at 200 ° C for 12 h. The effect of different dealumination times on the catalytic activity of the catalyst was evaluated by the results of catalytic reduction of carbon dioxide by glycerol. The results are shown in Figure 2. Figure 1 shown.

[0059] from Figure 1 It can be seen that when the dealumination time is 0, that is, the support is not dealuminated, a small amount of lactic acid and formic acid are generated in the reaction; when the support is dealuminated for 3 hours, the catalytic effect is greatly improved, and 4.30% lactic acid and 14.18% formic acid can be generated; when the support is dealuminated for 5 hours, the yields of lactic acid and formic acid are 5.21% and 14.64%, respectively, at this time the yields of the two are the highest; continue to increase the dealumination time, when the REUSY type molecular sieve is dealuminated for 10 hours, the yields of lactic acid and formic acid decrease slightly, the lactic acid yield decreases to 3.86%, and the formic acid yield decreases to 13.22%; as the dealumination time continues to increase, that is, theoretically the aluminum in the molecular sieve has been completely removed by concentrated nitric acid, the yields of lactic acid and formic acid decrease rapidly, and the catalytic effect is worse than when no dealumination is performed, with a formic acid yield of only 2.66%.

[0060] Example 2:

[0061] This embodiment provides a method for preparing Ru-REUSY molecular sieve that has not been surface aminated and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid.

[0062] (1) The specific steps of the preparation method of Ru-REUSY molecular sieve are as follows:

[0063] (1) 5 g of REUSY molecular sieve and 100 mL of concentrated nitric acid were poured into a flask and stirred at 200 rpm in a water bath at 80 °C for 3 h, 5 h, and 10 h for dealumination.

[0064] The dealuminated mixture was centrifuged and washed 6-7 times with deionized water until the pH of the wash solution was neutral. The washed solid was dried at 105°C for 2 hours to remove moisture and then at 150°C for 10 hours to remove inorganic impurities, yielding the deAl(3 / 5 / 10h)-REUSY support.

[0065] (2) RuCl3·3H2O was prepared into solutions with concentrations of 2 wt.%, 5 wt.%, 8 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, and 30 wt.%, respectively. 0.1 g of deAl(3 / 5 / 10h)-REUSY catalyst was suspended in the RuCl3 solution to prepare mixtures with different loading amounts.

[0066] (3) The mixture was sonicated in an ultrasonic machine for 30 min, allowed to stand for 12 h after uniform mixing, and then dried in an oven at 120°C for 12 h. Finally, it was calcined in air at 550°C for 6 h in a tube furnace to obtain Ru-deAl(3 / 5 / 10h)-REUSY catalysts with different loadings.

[0067] (II) Application of the prepared supported catalyst:

[0068] 20 mL of glycerol solution (0.33 M) and 7.92 g of KHCO3 were used as reaction substrates. 0.1 g of Ru-deAl(3 / 5 / 10h)-REUSY catalyst with different loadings was added and reacted at 200°C for 12 h. X-ray diffraction was performed on catalysts with loadings of 2 wt.%, 5 wt.%, 10 wt.%, and 20 wt.%. The XRD patterns of the catalysts with different Ru loadings are shown in the figure below. Figure 2 As shown (the catalysts with different Ru loading amounts and a dealumination time of 5h are selected here).

[0069] from Figure 2It can be seen from the XRD spectrum that the Ru-REUSY molecular sieve has obvious RuO2 diffraction peaks at 2θ=28.0°, 35.0° and 54.2°, which correspond to the (110), (101) and (211) crystal planes of RuO2, respectively, and the diffraction intensity of these three places gradually increases with the increase of the loading amount.

[0070] The XPS spectrum of the catalyst with a loading of 15 wt.% was scanned in the range of 0-1200 eV. The XPS spectrum of 15 wt% Ru-deAl(5h)-REUSY is as follows: Figure 3 As shown. Figure 3 It can be seen from the figure that the catalyst is indeed loaded with metal Ru, whose binding energy is 284.04eV(3d). Similarly, we also detected metal Re.

[0071] The effect of different Ru loadings on the catalytic activity of the catalyst was evaluated by the results of catalytic reduction of carbon dioxide by glycerol. Figure 4 As shown in the figure (the marks 3h, 5h, and 10h in the figure represent the yields of formic acid and lactic acid at different dealumination times). At different dealumination times, with the increase of catalyst Ru loading, the yields of the products lactic acid and formic acid always show an increasing trend.

[0072] Analysis of the 5-hour dealumination period revealed that increasing the Ru loading from 0 wt.% to 5 wt.% rapidly increased the yield of formic acid from an initial 2.30% to 13.07%, while the yield of lactic acid also rapidly increased from 1.09% to 3.74%. Increasing the Ru loading from 5 wt.% to 10 wt.% continued to increase rapidly, though at a slightly slower rate than in the first stage. At a Ru loading of 10 wt.%, the yields of formic acid and lactic acid reached 14.64% and 5.21% respectively. Further increases in Ru loading from 10 wt.% to 30 wt.% resulted in further increases in formic acid and lactic acid yields, ultimately reaching 19.13% and 6.63% respectively. The catalyst with a 10 wt.% Ru loading was found to be the most active catalyst under these conditions.

[0073] Example 3:

[0074] This embodiment provides a method for preparing Ru-REUSY molecular sieve that has not been surface aminated and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid.

[0075] (1) The specific steps of the preparation method of Ru-REUSY molecular sieve are as follows:

[0076] (1) 5 g of REUSY molecular sieve and 100 mL of concentrated nitric acid were poured into a flask and stirred at 200 rpm in a water bath at 80 °C for 3 h, 5 h, and 10 h for dealumination.

[0077] The dealuminated mixture was centrifuged and washed 6-7 times with deionized water until the pH of the wash solution was neutral. The washed solid was dried at 105°C for 2 hours to remove moisture and then at 150°C for 10 hours to remove inorganic impurities, yielding the deAl(3 / 5 / 10h)-REUSY support.

[0078] (2) RuCl3·3H2O was prepared into a solution with a concentration of 10 wt.%, and 0.1 g of deAl(3 / 5 / 10h)-REUSY catalyst was suspended in the RuCl3 solution to prepare a mixture with a loading of 10 wt.%.

[0079] (3) The mixture was sonicated in an ultrasonic machine for 30 minutes, allowed to stand for 12 hours after uniform mixing, and then dried in an oven at 120°C for 12 hours. Finally, it was calcined in air at 550°C for 6 hours in a tube furnace to obtain a 10 wt% Ru-deAl(3 / 5 / 10h)-REUSY catalyst.

[0080] (II) Application of the prepared supported catalyst:

[0081] 20 mL of glycerol solution (0.33 M) and 7.92 g of KHCO 3 were used as reaction substrates, and 0.1 g of 10 wt.% Ru-deAl (3 / 5 / 10 h)-REUSY catalyst was added respectively, and the reaction was carried out at two temperatures of 200° C. for 6 h, 12 h, 24 h, 36 h, and 48 h.

[0082] The effect of reaction time on the catalytic performance of 10 wt.% Ru-deAl (3 / 5 / 10 h)-REUSY was evaluated by the results of catalytic reduction of carbon dioxide by glycerol. Figure 5 As shown (the marks 3h, 5h, and 10h in the figure represent the yields of formic acid and lactic acid at different dealumination times). At different dealumination times, as the reaction time increases, the yields of formic acid and lactic acid both show a trend of first increasing and then decreasing. Still analyzing with dealumination for 5h, after 24h of reaction, the formic acid yield can reach 16.72% and the lactic acid yield can reach 5.18%. By further extending the reaction time, the highest formic acid and lactic acid yields can be reached at 36h of reaction, at which time, the yields are approximately 19.8% and 6.13%; if the reaction time is further extended to 48h, the lactic acid yield will decrease slightly, mainly due to the decomposition of lactic acid in the system.

[0083] Example 4:

[0084] This embodiment provides a method for preparing Ru-REUSY molecular sieve that has not been surface aminated and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid.

[0085] (1) The specific steps of the preparation method of Ru-REUSY molecular sieve are as follows:

[0086] (1) 5 g of REUSY molecular sieve and 100 mL of concentrated nitric acid were poured into a flask and stirred at 200 rpm in a water bath at 80 °C for 5 h for dealumination.

[0087] The dealuminated mixture was centrifuged and washed 6-7 times with deionized water until the pH of the washing solution was neutral. The washed solid was dried at 105°C for 2 hours to remove moisture and then at 150°C for 10 hours to remove inorganic impurities, obtaining the deAl(5h)-REUSY support.

[0088] (2) RuCl3·3H2O was prepared into a solution with a concentration of 10 wt.%, and 0.1 g of deAl(5h)-REUSY catalyst was suspended in the RuCl3 solution to prepare a mixture with a loading of 10 wt.%.

[0089] (3) The mixture was sonicated in an ultrasonic machine for 30 minutes, allowed to stand for 12 hours after uniform mixing, and then dried in an oven at 120°C for 12 hours. Finally, it was calcined in air at 550°C in a tube furnace for 6 hours to obtain a 10 wt% Ru-deAl(5h)-REUSY catalyst.

[0090] (II) Application of the prepared supported catalyst:

[0091] 20 mL of glycerol solution (0.33 M) and 7.92 g of KHCO 3 were used as reaction substrates, and 0.1 g of 10 wt.% Ru-deAl(5h)-REUSY catalyst was added, and the reaction was carried out at 150° C. and 200° C. for 6 h, 12 h, 24 h, 36 h, and 48 h, respectively.

[0092] The effect of reaction temperature on the catalytic performance of 10 wt.% Ru-deAl(5h)-REUSY was evaluated by the results of catalytic reduction of carbon dioxide by glycerol. Figure 6 As shown. It can be seen that when the reaction time is fixed and the reaction temperature is increased, the yields of formic acid and lactic acid both increase accordingly, because appropriately high temperatures facilitate the dehydrogenation of glycerol, thereby providing strong reducing conditions to promote the conversion of carbon dioxide into formic acid. When the reaction temperature is fixed at 200°C, the formic acid yield can reach as high as 14.64% in the first 12 hours of the reaction. Further extending the reaction time to 24 hours, the formic acid yield continues to rise to 16.72%. In the following 12 hours, the formic acid yield slowly increases from 16.72% to 19.81%, at which point the yield reaches its highest. If the reaction time is further extended, the yield will decrease due to its instability. Similarly, when the reaction temperature is fixed at 150°C, the formic acid yield slowly increases to 2.86% from 1 hour to 36 hours of reaction. If the reaction time is further extended, the yield will also decrease slightly.

[0093] Taking the reaction efficiency into consideration, we selected 200°C and 36h as the optimal reaction temperature and time for subsequent studies. At this time, 10wt.% Ru-deAl(5h)-REUSY catalyzed the reduction of carbon dioxide by glycerol to produce 19.81% formic acid and 6.13% lactic acid.

[0094] Example 5:

[0095] This embodiment provides a method for preparing Ru-REUSY molecular sieve that has not been surface aminated and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid.

[0096] (1) The specific steps of the preparation method of Ru-REUSY molecular sieve are as follows:

[0097] (1) 5 g of REUSY molecular sieve and 100 mL of concentrated nitric acid were poured into a flask and stirred at 200 rpm in a water bath at 80 °C for 5 h and 10 h for dealumination.

[0098] The dealuminated mixture was centrifuged and washed 6-7 times with deionized water until the pH of the washing solution was neutral. The washed solid was dried at 105°C for 2 hours to remove moisture and then at 150°C for 10 hours to remove inorganic impurities, yielding the deAl(5 / 10h)-REUSY support.

[0099] (2) RuCl3·3H2O was prepared into a solution with a concentration of 10 wt.%, and 0.1 g of deAl(5 / 10h)-REUSY catalyst was suspended in the RuCl3 solution to prepare a mixture with a loading of 10 wt.%.

[0100] (3) The mixture was sonicated in an ultrasonic machine for 30 minutes, allowed to stand for 12 hours after uniform mixing, and then dried in an oven at 120°C for 12 hours. Finally, it was calcined in air at 550°C in a tube furnace for 6 hours to obtain a 10 wt.% Ru-deAl(5 / 10h)-REUSY catalyst.

[0101] (2) Reusability of the prepared supported catalyst:

[0102] 20 mL of 0.33 M glycerol solution and 7.92 g of KHCO₃ were used as the reaction substrates. 0.1 g of Ru-deAl(5 / 10h)-REUSY catalyst with different loadings was added and reacted at 200°C for 24 h. The catalytic performance of the recycled catalyst was investigated.

[0103] The recycling method steps are as follows:

[0104] (1) The remaining reaction solution was filtered through a sand core filter device equipped with a suction pump. The filter paper specification was 0.22 μm and was washed with distilled water several times to flush out impurities and achieve rapid filtration;

[0105] (2) Use tweezers to gently scrape the filter paper, and the solid catalyst is dried at 60 ° C in air for 2-3 minutes, and can be stored for further reaction. The XRD spectrum of the recovered Ru-REUSY catalyst is as follows Figure 7 shown.

[0106] from Figure 7 It is clearly visible that the first-recycled catalyst still exhibits reduced intensities of the RuO2 diffraction peaks at 2θ = 28.0°, 35.0°, and 54.2°, and some of the support-related peaks at 2θ = 10.0°-28.0° disappear. This is likely due to the loss of the active Ru component during acidification during sampling and multiple distilled water rinses during catalyst recovery, which in turn promotes the reaction by removing chloride ions and other ineffective components from the support. As the catalyst is further recycled, the intensity of the RuO2 diffraction peaks decreases significantly, significantly reducing the catalytic activity.

[0107] Example 6:

[0108] This example provides a method for preparing a surface-aminated Ru-REUSY molecular sieve and its application in catalyzing the reduction of carbon dioxide with glycerol to produce formic acid. A 10 wt.% Ru-deAl(10h)-REUSY catalyst was prepared according to the method of Example 4 and then surface-aminated. The amination steps are as follows:

[0109] Pour 250 mL of ethanol into a round-bottom flask, weigh 0.1 g of calcined 10 wt.% Ru-deAl(10h)-REUSY catalyst and disperse it in the ethanol solution. Then, add 50 μL of 3-aminopropyltrimethoxysilane. Stir the flask in an 80°C oil bath at 200 rpm for 6 hours. After cooling to room temperature, the mixture is washed with a large amount of ethanol and then dried in an unsealed container at 80°C for 12 hours to obtain the amination catalyst.

[0110] Application of the prepared amination catalyst:

[0111] Theoretically, potassium bicarbonate decomposes via the process of KHCO₃ → KOH + CO₂. Calculations indicate that 7.92g of KHCO₃ is equivalent to 3.48g of dry ice and 4.44g of KOH. Therefore, 20mL of 0.33M glycerol solution and 3.48g of dry ice were used as the reaction substrates, along with 0.1g of an amination catalyst, and the reaction was incubated at 200°C for 24h. At this point, the reduction of dry ice with glycerol catalyzed by surface-aminated Ru-deAl(10h)-ReUSY produced a formic acid yield of 57.31% and a lactic acid yield of 18.38%.

[0112] Comparative Example 1: Comparison of the effects of different carrier types on the catalytic activity of catalysts

[0113] 20 mL of glycerol solution (0.33 M) and 7.92 g of KHCO3 were used as reaction substrates, 0.1 g of catalyst was added to each, and the mixture was reacted at 200 °C for 12 h.

[0114] The control variables for the four reaction groups were: four molecular sieves directly loaded with 10 wt.% Ru element without dealumination, namely 10 wt.% Ru-Beta, 10 wt.% Ru-K10, 10 wt.% Ru-REUSY, and 10 wt.% Ru-LAY. The catalytic activity was evaluated by the results of catalytic reduction of carbon dioxide by glycerol. The results are shown in Figure 2. Figure 8 shown.

[0115] from Figure 8 It can be seen that 10wt.% Ru-Beta catalyzes the reduction of carbon dioxide by glycerol to produce 2.59% lactic acid and 6.91% formic acid. The activity of 10wt% Ru-K10 in catalyzing the reduction of carbon dioxide by glycerol is not high, and the yields of lactic acid and formic acid are approximately 2.03% and 3.18%, respectively. This may be because montmorillonite K10 was not pretreated before immobilization and its stability is not high.

[0116] In addition, from Figure 9 It can be seen from the XRD spectrum that the K10 carrier has only a large SiO2 diffraction peak at 2θ=26.6°. Compared with other carriers, it has fewer basic sites, so its promoting effect on glycerol dehydrogenation to produce lactic acid is weaker, resulting in low lactic acid production. Figure 8 In the case of 10 wt.% Ru-REUSY and 10 wt.% Ru-LAY as catalysts, the yields of lactic acid and formic acid were 3.11% and 7.60% (10 wt.% Ru-REUSY), 2.83% and 5.78% (10 wt.% Ru-LAY), respectively. Figure 9It can also be seen from the XRD spectrum that the REUSY type molecular sieve has obvious ReOx diffraction peaks at 2θ=24.28° and 31.20°; the LAY type molecular sieve has an obvious La2O3 diffraction peak at 2θ=27.25°. It is considered that its catalytic effect can be attributed to the rare earth elements Re and La.

[0117] Comparative Example 2: Effect of different carbon sources (dry ice and potassium bicarbonate) on yield

[0118] Theoretically, potassium bicarbonate can be decomposed by KHCO3-KOH+CO2. After calculation, 7.92g KHCO3 is equivalent to 3.48g dry ice and 4.44g KOH.

[0119] Under the optimal conditions described above, 20 mL of 0.33 M glycerol solution was used as the reaction substrate. Different amounts of CO(s) and KOH, along with 0.1 g of 10 wt.% Ru-deAl(5h)-REUSY and 10 wt.% Ru-deAl(10h)-REUSY catalysts, were added, respectively, and the reaction was carried out at 200°C for 24 h. Table 1 shows the comparative results.

[0120] Table 1 Catalytic reaction of glycerol reducing dry ice

[0121]

[0122] As can be seen from Table 1, under alkali-free conditions, almost no lactic acid is produced in the reaction of glycerol reducing dry ice, while formic acid is produced in trace amounts under the action of the two catalysts, with yields of 3.02% and 2.18%, respectively.

[0123] Under normal conditions of base and dry ice addition, Ru-deAl(5h)-REUSY catalyzed the reduction of dry ice with glycerol, resulting in a lactic acid yield of 17.13%, exceeding the 11.87% yield achieved by Ru-deAl(10h)-REUSY. Furthermore, formic acid yields reached as high as 64.14% (deAl-5h) and 46.83% (deAl-10h). Compared to the yields achieved by the two catalysts above under the same conditions for the reduction of carbon dioxide with glycerol, the yields of both formic and lactic acids were significantly improved.

[0124] Reduction of dry ice with Ru-deAl(5h)-REUSY yielded 17.13% lactic acid and 64.14% formic acid, significantly higher than the 5.18% lactic acid and 16.71% formic acid yields obtained from the reduction of KHCO₃. This suggests that, in actual reactions, 1 mmol of KHCO₃ is not equivalent to 1 mmol of CO₂ and 1 mmol of KOH; the amount of alkalinity and reactive carbon dioxide provided is relatively low. Furthermore, the high pressure generated by the substantial volume expansion of dry ice during sublimation can accelerate the reaction.

[0125] Comparative Example 3: Effect of surface amination on catalyst basicity

[0126] The amination catalyst was prepared according to the method of Example 5.

[0127] Application of the prepared amination catalyst:

[0128] 20 mL of glycerol solution (0.33 M) and 3.48 g of dry ice were used as reaction substrates, and three levels of KOH (0 g (no alkali), 2.22 g (half alkali), and 4.44 g (full alkali) and 0.1 g of amination catalyst were added, respectively, and the reaction was carried out at 200 °C for 24 h.

[0129] Table 2 shows the effect of surface amination on catalyst basicity. As can be seen from Table 2, when the amination catalyst alone is present, the glycerol reduction of carbon dioxide yields a formic acid yield of 12.60% and a lactic acid yield of 3.54% (row 1). Compared with the yields in row 2 of Table 1, it can be seen that the amination catalyst does have a base-catalyzed effect, increasing the lactic acid yield from 0.31% to 3.54%. Simultaneously, the formic acid yield is significantly increased due to the dehydrogenation of glycerol to lactic acid. With the continued addition of KOH, the lactic acid yield continues to rise, from 9.85% in the semi-alkaline state to 18.38%. The addition of solid base still promotes the production of lactic acid from glycerol, indicating that the amination catalyst's basicity is insufficient. As can be seen from row 3 of Table 2, the combined action of the amination catalyst and solid base in the glycerol reduction of dry ice yields of 57.31% and 18.38% at 200°C for 24 hours. Therefore, how to continue to increase the alkalinity of the amination catalyst is also a future research direction.

[0130] Table 2 Effect of surface amination on catalyst basicity

[0131]

[0132] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A surface aminated Ru-REUSY molecular sieve catalyst, characterized in that: The preparation method of the molecular sieve catalyst comprises the following steps: (1) Pour commercial-grade carrier REUSY molecular sieve and concentrated nitric acid into a container, maintain the temperature at 70-90°C, and stir at a rate of 200-300 rpm for 3-20 hours to carry out dealumination; the mass volume ratio of the carrier REUSY molecular sieve to concentrated nitric acid is 5-10g:100-200ml; The dealuminated mixture was centrifuged at 2500-3500 rpm and then washed with deionized water until the pH of the washing solution was neutral. The washed solid was dried to obtain the dealuminated support deAl-REUSY, which was used as the matrix for the liquid impregnation method. (2) preparing a RuCl3·3H2O solution having a concentration in the range of 2 wt.% to 30 wt.%, taking 1 g of the dealuminated support deAl-REUSY obtained in step (1) and suspending it in the RuCl3 solution to obtain a mixture of ruthenium and molecular sieve; The mixture was ultrasonicated in an ultrasonic machine for 30-40 minutes, allowed to stand and dried after being mixed evenly; and then calcined in a tube furnace at 550-565° C. under air conditions for 5-6 hours to obtain a ruthenium-supported catalyst Ru-REUSY; (3) Surface amination: Pour ethanol into a round-bottom flask, and disperse the Ru-REUSY catalyst obtained in step (2) in the ethanol solution; the mass volume ratio of the Ru-REUSY catalyst to ethanol is 0.5-1 g: 250-2500 ml; Then, the amination reagent is added, and the round-bottom flask is stirred in an oil bath at 75-85°C at a rate of 150-250 rpm for 4-6 hours; the mass volume ratio of the Ru-REUSY catalyst to the amination reagent is 0.5-1 g: 50-200 μL; Finally, the mixture of the product obtained after stirring is cooled to room temperature and washed with a large amount of ethanol, and then dried to obtain an amination catalyst.

2. The molecular sieve catalyst according to claim 1, characterized in that The concentration of the concentrated nitric acid in step (1) is 65.0-68.0%; the drying method is to first dry the washed solid at 105-110°C for 1.5-2.5 hours to remove moisture, and then dry it at 150-160°C for 10-12 hours to remove inorganic impurities.

3. The molecular sieve catalyst according to claim 1, characterized in that The standing time in step (2) is 10-12 hours, and the drying is performed at 115-125° C. for 10-12 hours.

4. The molecular sieve catalyst according to claim 1, characterized in that The amination reagent in step (3) is any one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-aminoethyl-3-aminopropyltrimethoxysilane, and N-aminoethyl-3-aminopropylmethyldimethoxysilane; The drying step is to dry the mixture in a non-sealed container at 80-85° C. for 10-12 hours.

5. Use of the surface aminated Ru-REUSY molecular sieve catalyst according to any one of claims 1 to 4, characterized in that: Used for catalyzing glycerol to reduce carbon dioxide to formic acid; the specific steps of the application include: S1. Stirring the glycerol solution, carbon dioxide source, base, and surface aminated Ru-REUSY molecular sieve catalyst in a reactor; S2. Then fix the reactor on the rotating shaft of the rotary oven, heat it to 150-200°C, and keep it for 24-36 hours; S3. After the set reaction time, quickly transfer to an ice water bath and cool to 25°C.

6. The use according to claim 5, characterized in that The ratio of the carbon dioxide source to glycerol is in the range of 2.64-10.56 g:6.6 mmol; the ratio of the surface aminated Ru-REUSY molecular sieve catalyst addition to glycerol is in the range of 0.02-0.2 g:6.6 mmol; and the ratio of the base addition to glycerol is in the range of 2.22-6.66 g:6.6 mmol.

7. The use according to claim 5, characterized in that The carbon dioxide source includes alkali metal carbonates, alkaline earth metal carbonates, subgroup metal carbonates, alkali metal bicarbonates, ammonium carbonate or dry ice.

8. The use according to claim 5, characterized in that The base includes KOH and NaOH.

9. The use according to claim 5, characterized in that The glycerol solution is an aqueous solution of glycerol, and its concentration range is 0.33-2.67 mol / L.

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