A bimetallic ceria-based catalyst, its preparation method and use

Abstract

The application belongs to the technical field of sewage treatment, and provides a bimetallic ceria-based catalyst, a preparation method and application thereof. The preparation method comprises the following steps: immersing a ceria carrier in a mixed solution of a Rh salt and a transition metal salt to obtain a catalyst precursor; and sequentially performing calcination and reduction on the catalyst precursor to obtain the bimetallic ceria-based catalyst. Compared with a single metal catalyst, the bimetallic ceria-based catalyst has abundant active sites, and the synergistic effect of the bimetallic catalyst effectively improves the activity of the catalyst; the Rh metal particles are uniformly dispersed, the electronic effect of the bimetallic catalyst is conducive to the formation of oxygen vacancies on the surface of the carrier, can mutually adjust the electronic structure, and has good anti-chloride ion interference performance; the preparation method is simple and easy to operate, and has good application prospect.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a bimetallic cerium oxide-based catalyst, its preparation method, and its application. Background Technology

[0002] The use of chlorine-containing disinfectants and the electrolysis process in the chlor-alkali industry can generate toxic substances such as chlorate (ClO3). - Excessive chlorate intake can damage the digestive and central nervous systems, while also increasing the burden on the kidneys. As a strong oxidizing byproduct, chlorate negatively impacts industrial production processes and poses a potential and persistent environmental hazard. For these reasons, the World Health Organization has set a provisional guideline of 70 μg / L (approximately 8.3 μM) for chlorate concentrations in drinking water. Therefore, effectively controlling chlorate emissions is of great significance for sustainable development and environmental protection.

[0003] For drinking water, common chlorate treatment methods include biological reduction, adsorption, and catalytic reduction. While biological reduction produces no secondary waste and has low treatment costs, the selectivity of microorganisms in adsorption and reduction for chlorate is low, resulting in unstable treatment effects. Adsorption methods primarily use activated carbon, which faces the challenge of regenerating the activated carbon after adsorption saturation. In the chlor-alkali industrial electrolysis process, chlorate, as a byproduct, reduces electrolysis efficiency. To remove accumulated chlorate from the system, direct discharge or chemical removal methods are generally adopted. While direct discharge is fast and effective for industrial applications, the resulting wastewater harms the aquatic environment. Chemical removal involves adding large amounts of hydrochloric acid to the electrolysis system to neutralize the OH- ions. - However, this method must be carried out at high temperatures, and the addition of a large amount of hydrochloric acid increases the degree of corrosion to the equipment.

[0004] Liquid-phase catalytic hydrogenation reduction involves dispersing a solid catalyst in a contaminant solution and using hydrogen as a reducing agent. The reduction reaction is carried out at room temperature and pressure, offering advantages such as ease of operation, high efficiency, and cleanliness. Supported catalysts are commonly used in liquid-phase catalytic hydrogenation reduction. However, currently, supported single-metal catalysts do not show ideal performance for the liquid-phase catalytic hydrogenation reduction of chlorates, and also face challenges related to the product (Cl...). - Irreversible adsorption of Rh metals on the catalyst surface leads to catalyst poisoning. Studies have shown that Rh-based catalysts exhibit high hydrogenation reduction activity, and the addition of non-noble metals may alter the electronic structure of Rh, promoting the production of (Cl... - The desorption of ) is possible, but there is currently little research in this area.

[0005] Therefore, a bimetallic cerium oxide-based catalyst was developed to effectively avoid the problems caused by Cl in the liquid-phase catalytic hydrogenation reduction of chlorate through bimetallic active sites. -Catalyst poisoning caused by adsorption can be effectively addressed by stabilizing the removal of chlorate, showing promising application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a bimetallic cerium oxide-based catalyst, its preparation method, and its application, addressing the shortcomings of existing technologies.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing a bimetallic cerium oxide-based catalyst, comprising the following steps:

[0009] (1) The cerium oxide support was impregnated in a mixed solution of Rh salt and transition metal salt to obtain a catalyst precursor;

[0010] (2) The catalyst precursor is calcined and reduced in sequence to obtain the bimetallic cerium oxide-based catalyst.

[0011] Preferably, in the mixed solution described in step (1), the concentration of Rh salt is 0.02–0.03 mg / mL, the concentration of transition metal salt is 0.2–1.5 mg / mL, and the volume-to-mass ratio of the mixed solution to the cerium oxide support is 40 mL: 100–500 mg.

[0012] The impregnation time is 3 to 6 hours; the impregnation is carried out by stirring at a speed of 500 to 1000 rpm.

[0013] Preferably, the Rh salt in step (1) comprises one or more of Rh(NO3)3, RhCl3 and (NH4)3RhCl6;

[0014] The transition metal in the transition metal salt is Ni or Co;

[0015] When the transition metal is Ni, the transition metal salt contains one or more of Ni(CH3COO)2, Ni(CH3COO)2·4H2O and Ni(NO3)2·6H2O;

[0016] When the transition metal is Co, the transition metal salt contains Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

[0017] Preferably, the calcination temperature in step (2) is 300-400℃ and the calcination time is 4-6h; the reduction is carried out by hydrogen reduction, and the flow rate of hydrogen is 10-40mL / min; the reduction temperature is 100-500℃ and the reduction time is 1-2h.

[0018] Preferably, the preparation method of the cerium oxide support in step (1) includes the following steps:

[0019] 1) Ammonia water is added dropwise to Ce(NO3)2·6H2O solution to obtain a mixed solution. The mixed solution reacts to obtain a solid product.

[0020] 2) The solid products are dried and calcined in sequence to obtain cerium oxide support.

[0021] Preferably, the concentration of the ammonia solution in step 1) is 0.1–0.5 mol / L, and the concentration of the Ce(NO3)2·6H2O solution is 0.1–0.5 mol / L.

[0022] The dripping rate is 2-10 mL / min, and the ammonia dripping is stopped when the pH of the mixed solution is 9-11;

[0023] The reaction is carried out under stirring at a speed of 500–1000 rpm for 2–4 hours.

[0024] Preferably, the drying temperature in step 2) is 80–110°C and the drying time is 6–14 h; the calcination temperature is 400–600°C and the calcination time is 4–6 h.

[0025] The present invention also provides a bimetallic cerium oxide-based catalyst prepared by the aforementioned preparation method.

[0026] The present invention also provides the application of the bimetallic cerium oxide-based catalyst in the liquid-phase catalytic hydrogenation reduction of chlorate, wherein the bimetallic cerium oxide-based catalyst is added to chlorate water to carry out the catalytic hydrogenation reaction;

[0027] The mass-to-volume ratio of the bimetallic cerium oxide-based catalyst to the chlorate water is 0.10–0.25 g: 1 L.

[0028] Preferably, the concentration of chlorate in the chlorate water is 0.2–1.0 mmol / L;

[0029] The temperature of the catalytic hydrogenation reaction is 20–40°C, the reaction time is 1.5–2.5 h, and the hydrogen flow rate is 100–200 mL / min.

[0030] The beneficial effects of this invention include the following:

[0031] 1) Compared with single metal catalysts, the bimetallic cerium oxide-based catalyst of the present invention has abundant active sites, and the synergistic effect of bimetals effectively improves the activity of the catalyst; the Rh metal particles are uniformly dispersed, and the electronic effect of bimetals is conducive to the formation of oxygen vacancies on the support surface, which can mutually regulate the electronic structure, and at the same time have good resistance to chloride ion interference.

[0032] 2) The preparation method of the present invention is simple, easy to operate, and has good application prospects. Attached Figure Description

[0033] Figure 1 Transmission electron microscopy (TEM) images of the cerium oxide-based catalysts prepared in Examples 1, 2 and Comparative Example 1;

[0034] Figure 2 Wide-angle X-ray diffraction patterns of the cerium oxide-based catalysts and cerium oxide supports prepared in Example 1 and Comparative Examples 1 and 2;

[0035] Figure 3 The Raman spectra of the cerium oxide-based catalysts prepared in Examples 1, 2 and Comparative Example 1 are shown in Figure (a), where the wavenumbers are 300–1500 cm⁻¹. -1 Raman spectra, Figure (b) shows the wavenumbers from 200 to 600 cm⁻¹. -1 Raman spectra;

[0036] Figure 4 In-situ infrared spectra of CO adsorption for the cerium oxide-based catalysts prepared in Examples 1, 2 and Comparative Example 1;

[0037] Figure 5 The X-ray photoelectron spectra of the cerium oxide-based catalysts prepared in Example 1 and Comparative Examples 1 and 2 are shown in Figure (a), which is the X-ray photoelectron spectrum of Ce 3d, Figure (b) is the X-ray photoelectron spectrum of O 1s, Figure (c) is the X-ray photoelectron spectrum of Ni 2p, and Figure (d) is the X-ray photoelectron spectrum of Rh 3d.

[0038] Figure 6 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate are shown in Experimental Examples 1-3 and Comparative Experimental Examples 1-2.

[0039] Figure 7 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1, 4-6 are shown.

[0040] Figure 8 The reaction diagrams for the liquid-phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1, 7-9 are shown. Figure (a) is the reaction curve of the liquid-phase catalytic hydrogenation reduction of chlorate, and Figure (b) is the linear fitting curve of discrete data of 1 / C0 (C0 is the chlorate concentration) and 1 / r0 (r0 is the reaction rate).

[0041] Figure 9 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate in Examples 1 and 10 are shown.

[0042] Figure 10 To compare the reaction curves of liquid-phase catalytic hydrogenation reduction of chlorate in Experiment Examples 1 and 3;

[0043] Figure 11 The reaction curve for the cyclic test of Experimental Example 1. Detailed Implementation

[0044] This invention provides a method for preparing a bimetallic cerium oxide-based catalyst, comprising the following steps:

[0045] (1) The cerium oxide support was impregnated in a mixed solution of Rh salt and transition metal salt to obtain a catalyst precursor;

[0046] (2) The catalyst precursor is calcined and reduced in sequence to obtain the bimetallic cerium oxide-based catalyst.

[0047] In this invention, in the mixed solution described in step (1), the concentration of Rh salt is preferably 0.02-0.03 mg / mL, more preferably 0.022-0.028 mg / mL, and even more preferably 0.025 mg / mL; the concentration of transition metal salt is preferably 0.2-1.5 mg / mL, more preferably 0.25-1.25 mg / mL, and even more preferably 0.5-1 mg / mL; the volume-to-mass ratio of the mixed solution to the cerium oxide support is preferably 40 mL: 100-500 mg, more preferably 40 mL: 200-400 mg, and even more preferably 40 mL: 300 mg.

[0048] The soaking time is preferably 3 to 6 hours, more preferably 4 to 5 hours; the soaking is preferably carried out by stirring, and the stirring speed is preferably 500 to 1000 rpm, more preferably 600 to 800 rpm, and more preferably 700 rpm.

[0049] In this invention, after impregnation in step (1), it is preferable to evaporate the catalyst precursor to obtain the catalyst precursor. The evaporation temperature is preferably 80-90°C, and more preferably 85°C. The evaporation time is preferably 1-2 hours, and more preferably 1.5 hours.

[0050] In this invention, the Rh salt in step (1) preferably includes one or more of Rh(NO3)3, RhCl3 and (NH4)3RhCl6;

[0051] The transition metal in the transition metal salt is preferably Ni or Co;

[0052] When the transition metal is Ni, the transition metal salt preferably contains one or more of Ni(CH3COO)2, Ni(CH3COO)2·4H2O and Ni(NO3)2·6H2O;

[0053] When the transition metal is Co, the transition metal salt preferably contains Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

[0054] In this invention, the calcination temperature in step (2) is preferably 300-400℃, more preferably 330-380℃, and even more preferably 350℃; the calcination time is preferably 4-6h, more preferably 4.5-5.5h, and even more preferably 5h; the reduction is preferably carried out using hydrogen reduction, and the hydrogen flow rate is preferably 10-40mL / min, more preferably 20-30mL / min; the reduction temperature is preferably 100-500℃, more preferably 200-400℃, and even more preferably 300℃; the reduction time is preferably 1-2h, and even more preferably 1.5h.

[0055] In this invention, the method for preparing the cerium oxide support in step (1) preferably includes the following steps:

[0056] 1) Ammonia water is added dropwise to Ce(NO3)2·6H2O solution to obtain a mixed solution. The mixed solution reacts to obtain a solid product.

[0057] 2) The solid products are dried and calcined in sequence to obtain cerium oxide support.

[0058] In this invention, the concentration of the ammonia solution in step 1) is preferably 0.1–0.5 mol / L, more preferably 0.2–0.4 mol / L, and even more preferably 0.3 mol / L; the concentration of the Ce(NO3)2·6H2O solution is preferably 0.1–0.5 mol / L, more preferably 0.2–0.4 mol / L, and even more preferably 0.3 mol / L.

[0059] The dripping rate is preferably 2-10 mL / min, more preferably 4-8 mL / min, and even more preferably 6 mL / min; the pH of the mixed solution is preferably 9-11 when the ammonia dripping is stopped, more preferably 9.5-10.5, and even more preferably 10.

[0060] The reaction is preferably carried out by stirring, with the stirring speed preferably being 500-1000 rpm, more preferably 600-800 rpm, and even more preferably 700 rpm; the stirring time is preferably 2-4 h, more preferably 2.5-3.5 h, and even more preferably 3 h.

[0061] In this invention, the drying temperature in step 2) is preferably 80-110℃, more preferably 90-105℃, and even more preferably 100℃; the drying time is preferably 6-14h, more preferably 8-12h, and even more preferably 10h; the calcination temperature is preferably 400-600℃, more preferably 450-550℃, and even more preferably 500℃; the calcination time is preferably 4-6h, more preferably 4.5-5.5h, and even more preferably 5h.

[0062] The present invention also provides a bimetallic cerium oxide-based catalyst prepared by the aforementioned preparation method.

[0063] The present invention also provides the application of the bimetallic cerium oxide-based catalyst in the liquid-phase catalytic hydrogenation reduction of chlorate, wherein the bimetallic cerium oxide-based catalyst is added to chlorate water to carry out the catalytic hydrogenation reaction;

[0064] The preferred mass-to-volume ratio of the bimetallic cerium oxide-based catalyst to the chlorate water is 0.10–0.25 g: 1 L, more preferably 0.15–0.2 g: 1 L.

[0065] In this invention, the concentration of chlorate in the chlorate water is preferably 0.2–1.0 mmol / L, more preferably 0.25–0.8 mmol / L, and even more preferably 0.4–0.6 mmol / L;

[0066] The preferred temperature for the catalytic hydrogenation reaction is 20–40°C, more preferably 25–35°C, and even more preferably 30°C; the preferred time for the catalytic hydrogenation reaction is 1.5–2.5 h, and even more preferably 2 h; the preferred hydrogen flow rate for the catalytic hydrogenation reaction is 100–200 mL / min, more preferably 130–180 mL / min, and even more preferably 150 mL / min.

[0067] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] 0.5 mol / L ammonia solution was added dropwise to 500 mL of a 0.5 mol / L Ce(NO3)2·6H2O solution at a rate of 6 mL / min to obtain a mixed solution. The addition was stopped when the pH of the mixed solution reached 10. The mixed solution was stirred at 700 rpm for 3 h and then filtered to obtain a solid product. The solid product was dried at 105 °C for 8 h and then calcined in a muffle furnace at 500 °C for 5 h to obtain a cerium oxide support.

[0070] A mixed aqueous solution of Rh(NO3)3 and Ni(NO3)2·6H2O was prepared, wherein the concentration of Rh(NO3)3 was 0.025 mg / mL and the concentration of Ni(NO3)2·6H2O was 1.25 mg / mL. 100 mg of cerium oxide support was immersed in 40 mL of the mixed aqueous solution for 4 h (the solution was stirred at 700 rpm during immersion) to obtain a catalyst precursor solution. The catalyst precursor solution was evaporated to dryness at 85 °C for 1.5 h to obtain the catalyst precursor.

[0071] The catalyst precursor was placed in a muffle furnace and calcined at 300 °C for 4 h, and then reduced in hydrogen gas at 200 °C for 2 h at a flow rate of 20 mL / min to obtain a bimetallic cerium oxide-based catalyst.

[0072] The bimetallic cerium oxide-based catalyst prepared in this embodiment is labeled RhNi. 10 / CeO2.

[0073] Example 2

[0074] The concentration of Ni(NO3)2·6H2O in the mixed aqueous solution of Example 1 was modified to 0.25 mg / mL, and the rest was the same as in Example 1.

[0075] The bimetallic cerium oxide-based catalyst prepared in this embodiment is labeled as RhNi2 / CeO2.

[0076] Example 3

[0077] In Example 1, Ni(NO3)2·6H2O in the mixed aqueous solution was replaced with Co(NO3)2·6H2O, and everything else was the same as in Example 1.

[0078] The bimetallic cerium oxide-based catalyst prepared in this embodiment is labeled as RhCo / CeO2.

[0079] Example 4

[0080] 0.3 mol / L ammonia solution was added dropwise to 500 mL of a 0.3 mol / L Ce(NO3)2·6H2O solution at a rate of 8 mL / min to obtain a mixed solution. The addition was stopped when the pH of the mixed solution reached 10. The mixed solution was stirred at 1000 rpm for 2 h and then filtered to obtain a solid product. The solid product was dried at 80 °C for 14 h and then calcined in a muffle furnace at 600 °C for 4 h to obtain a cerium oxide support.

[0081] A mixed aqueous solution of RhCl3 and Ni(CH3COO)2 was prepared, wherein the concentration of RhCl3 was 0.03 mg / mL and the concentration of Ni(CH3COO)2 was 0.5 mg / mL. 300 mg of cerium oxide support was immersed in 40 mL of the mixed aqueous solution for 6 h (the solution was stirred at 500 rpm during immersion) to obtain a catalyst precursor solution. The catalyst precursor solution was evaporated to dryness at 80 °C for 2 h to obtain the catalyst precursor.

[0082] The catalyst precursor was placed in a muffle furnace and calcined at 350 °C for 5 h, and then reduced at 300 °C for 1.5 h in hydrogen gas at a flow rate of 30 mL / min to obtain a bimetallic cerium oxide-based catalyst.

[0083] Example 5

[0084] 0.1 mol / L ammonia solution was added dropwise to 500 mL of 0.1 mol / L Ce(NO3)2·6H2O solution at a rate of 2 mL / min to obtain a mixed solution. The addition was stopped when the pH of the mixed solution reached 11. The mixed solution was stirred at 500 rpm for 4 h and then filtered to obtain a solid product. The solid product was dried at 100 °C for 10 h and then calcined in a muffle furnace at 400 °C for 6 h to obtain cerium oxide support.

[0085] A mixed aqueous solution of (NH4)3RhCl6 and Ni(CH3COO)2·4H2O was prepared, wherein the concentration of (NH4)3RhCl6 was 0.02 mg / mL and the concentration of Ni(CH3COO)2·4H2O was 1.25 mg / mL. 500 mg of cerium oxide support was immersed in 40 mL of the mixed aqueous solution for 3 h (the solution was stirred at 1000 rpm during immersion) to obtain a catalyst precursor solution. The catalyst precursor solution was evaporated to dryness at 90 °C for 1 h to obtain the catalyst precursor.

[0086] The catalyst precursor was placed in a muffle furnace and calcined at 400 °C for 6 h, and then reduced in hydrogen gas at 500 °C for 1 h at a flow rate of 40 mL / min to obtain a bimetallic cerium oxide-based catalyst.

[0087] Comparative Example 1

[0088] The mixed aqueous solution of Rh(NO3)3 and Ni(NO3)2·6H2O in Example 1 was replaced with an aqueous solution of Rh(NO3)3 with a concentration of 0.025 mg / mL, and the rest was the same as in Example 1.

[0089] The cerium oxide-based catalyst prepared in this comparative example is labeled Rh / CeO2.

[0090] Comparative Example 2

[0091] The mixed aqueous solution of Rh(NO3)3 and Ni(NO3)2·6H2O in Example 1 was replaced with an aqueous solution of Ni(NO3)2·6H2O with a concentration of 1.25 mg / mL, and the rest was the same as in Example 1.

[0092] The cerium oxide-based catalyst prepared in this comparative example is labeled as Ni / CeO2.

[0093] Figure 1 Transmission electron microscopy (TEM) images of the cerium oxide-based catalysts prepared in Examples 1, 2, and Comparative Example 1. Figure 1As can be seen, the bimetallic cerium oxide-based catalysts of Examples 1 and 2 exhibit distinct cerium oxide support morphologies, with clearly visible lattice fringes on the Ce (111) and Ni (111) crystal planes. A capping layer, consisting of amorphous cerium oxide, surrounds the Ni particles, and its formation is related to the strong interaction between the metal and the support. The monometallic cerium oxide-based catalyst of Comparative Example 1 also exhibits a distinct cerium oxide support morphology. Due to the strong interaction between the metal and the support, the Rh particles are relatively dispersed on the surface of the cerium oxide support.

[0094] Figure 2 Wide-angle X-ray diffraction patterns of the cerium oxide-based catalysts and cerium oxide supports prepared in Example 1 and Comparative Examples 1 and 2. Figure 2 It can be seen that the diffraction peaks of CeO2 at 28.3°, 33°, 47.3°, 56.2°, and 58.9° correspond to the (111), (200), (220), (311), and (222) crystal planes, respectively, belonging to the fluorite structure of cerium. Even after being loaded with metal, CeO2 still exhibits well-formed characteristic peaks of the cerium phase. RhNi 10 The 44.6° characteristic peak belonging to the Ni(111) crystal plane was observed on the / CeO2 and Ni / CeO2 spectra. Due to the Rh concentration being lower than the detection limit of XRD technology or the small particle size of Rh nanoparticles, the Rh phase was not detected in any of the Rh-containing catalysts.

[0095] Figure 3 The Raman spectra of the cerium oxide-based catalysts prepared in Examples 1, 2 and Comparative Example 1 are shown in Figure (a), where the wavenumbers are 300–1500 cm⁻¹. -1 Raman spectra, Figure (b) shows the wavenumbers from 200 to 600 cm⁻¹. -1 Raman spectra. (By...) Figure 3 It can be seen that the single-metal cerium oxide-based catalyst of Comparative Example 1 has a lower efficiency at 456 cm⁻¹. -1 A strong peak appeared at 595cm. -1 The weak peaks observed at 595 cm⁻¹ can be attributed to the vibrational modes of cerium oxide with a fluorite-type cubic structure and the defect-induced modes of oxygen vacancies in the cerium structure, respectively. Meanwhile, the bimetallic cerium oxide-based catalysts of Examples 1 and 2 showed a peak at 595 cm⁻¹. -1 The nearby bands are weaker than those of monometallic cerium oxide-based catalysts, at 456 cm⁻¹. -1 The banding intensity at that location did not change significantly. This indicates that the interaction between the bimetallic Rh and Ni occurs on the cerium oxide surface. Figure 3 As shown in Figure (b), the main peak of Rh / CeO2 shifts to a lower wavenumber after the introduction of Ni, and the shift increases with increasing Ni content, indicating that the bimetallic RhNi... 10 / CeO2 catalysts have more oxygen vacancies.

[0096] Figure 4 are in-situ infrared spectra of CO adsorption for the ceria-based catalysts prepared in Examples 1, 2 and Comparative Example 1. From Figure 4 it can be seen that both bimetallic ceria-based catalysts and monometallic ceria catalysts show CO bands corresponding to Rh single atoms (Rh iso ) at 2087 cm -1 and 2021 cm -1 , and CO bands corresponding to Rh nanoclusters (Rh NC ) at 2070 cm -1 ; the intensity of the CO peak on Rh nanoclusters decreases with the increase of Ni content. This indicates that both Rh nanoclusters and highly dispersed Rh single atoms exist in the ceria-based catalysts, and a higher Ni content improves the dispersion of Rh, which correspondingly increases the proportion of Rh single atom sites.

[0097] Figure 5 are X-ray photoelectron spectra of the ceria-based catalysts prepared in Example 1 and Comparative Examples 1 and 2, wherein, plot (a) is the X-ray photoelectron spectrum of Ce 3d, plot (b) is the X-ray photoelectron spectrum of O1s, plot (c) is the X-ray photoelectron spectrum of Ni 2p, and plot (d) is the X-ray photoelectron spectrum of Rh 3d. From Figure 5 it can be seen that, in terms of Ce content, Rh / CeO2 < RhNi 10 / CeO2 < Ni / CeO2, indicating that compared with the monometallic ceria-based catalyst Rh / CeO2, the doping of Ni stabilizes the electronic structure of ceria. In terms of oxygen, the surface of the monometallic ceria-based catalyst Ni / CeO2 has the highest oxygen vacancy concentration, followed by the bimetallic ceria-based catalyst, and the monometallic ceria-based catalyst Rh / CeO2 has the lowest, which shows that the doping of Ni effectively stabilizes the oxygen vacancies on the catalyst surface. In terms of metal particles, the bimetallic interaction leads to changes of metal particles: the Ni content in the bimetallic ceria-based catalyst is higher than that in the monometallic ceria-based catalyst Ni / CeO2, while the Rh content is lower than that in the monometallic ceria-based catalyst Rh / CeO2. Ni not only transfers electrons to the ceria support, but also generates electron transfer with Rh, which weakens the interaction between Rh and the ceria support.

[0098] Test Example 1

[0099] The bimetallic ceria-based catalyst RhNi prepared in Example 1 10 / CeO2 was added into a chlorate aqueous solution with a concentration of 0.4 mmol / L (the mass-volume ratio of the bimetallic ceria-based catalyst to the chlorate aqueous solution is 0.25 g: 1 L), and hydrogen was introduced at a flow rate of 150 mL / min, and the reaction was carried out at 25°C for 2 hours.

[0100] In this experimental example, the bimetallic cerium oxide-based catalyst RhNi 10 The catalytic activity of / CeO2 reached 21.52 mM / (g catalyst·h).

[0101] Experimental Example 2

[0102] The bimetallic cerium oxide-based catalyst RhNi from Experimental Example 1 10 / CeO2 was replaced with the bimetallic cerium oxide-based catalyst RhNi2 / CeO2 prepared in Example 2, and everything else was the same as in Experimental Example 1.

[0103] In this experimental example, the catalytic activity of the bimetallic cerium oxide-based catalyst RhNi2 / CeO2 reached 15.5 mM / (g catalyst·h).

[0104] Experimental Example 3

[0105] The bimetallic cerium oxide-based catalyst RhNi from Experimental Example 1 10 / CeO2 was replaced with the bimetallic cerium oxide-based catalyst RhCo / CeO2 prepared in Example 3, and everything else was the same as in Experimental Example 1.

[0106] In this experimental example, the catalytic activity of the bimetallic cerium oxide-based catalyst RhCo / CeO2 reached 12 mM / (g catalyst·h).

[0107] Test Example 4

[0108] The mass-to-volume ratio of the bimetallic cerium oxide-based catalyst and the chlorate water in Experiment Example 1 was modified to 0.1 g: 1 L, while other aspects remained the same as in Experiment Example 1.

[0109] In this experimental example, the bimetallic cerium oxide-based catalyst RhNi 10 The catalytic activity of / CeO2 reached 22 mM / (g catalyst·h).

[0110] Experimental Example 5

[0111] The mass-to-volume ratio of the bimetallic cerium oxide-based catalyst and the chlorate water in Experiment Example 1 was modified to 0.15 g: 1 L, while other aspects remained the same as in Experiment Example 1.

[0112] In this experimental example, the bimetallic cerium oxide-based catalyst RhNi 10 The catalytic activity of / CeO2 reached 21.5 mM / (g catalyst·h).

[0113] Experimental Example 6

[0114] The mass-to-volume ratio of the bimetallic cerium oxide-based catalyst and the chlorate water in Experiment Example 1 was modified to 0.2 g: 1 L, while other aspects remained the same as in Experiment Example 1.

[0115] In this experimental example, the bimetallic cerium oxide-based catalyst RhNi 10 The catalytic activity of / CeO2 reached 22.5 mM / (g catalyst·h).

[0116] Experimental Example 7

[0117] The concentration of chlorate in the water in Experiment Example 1 was modified to 0.25 mmol / L, while other parameters remained the same as in Experiment Example 1.

[0118] Experimental Example 8

[0119] The concentration of chlorate in the water in Experiment Example 1 was modified to 0.6 mmol / L, while other parameters remained the same as in Experiment Example 1.

[0120] Experimental Example 9

[0121] The concentration of chlorate in the water in Experiment Example 1 was modified to 1.0 mmol / L, while other parameters remained the same as in Experiment Example 1.

[0122] Experimental Example 10

[0123] Add 5 mmol / L of chloride ions to the chlorate water in Experiment Example 1, and do the same as in Experiment Example 1.

[0124] Comparative Test Example 1

[0125] The bimetallic cerium oxide-based catalyst RhNi from Experimental Example 1 10 / CeO2 was replaced with the cerium oxide-based catalyst Rh / CeO2 prepared in Comparative Example 1, and everything else was the same as in Experimental Example 1.

[0126] In this experimental example, the catalytic activity of the cerium oxide-based catalyst Rh / CeO2 was only 1 mM / (g catalyst·h).

[0127] Comparative Test Example 2

[0128] The bimetallic cerium oxide-based catalyst RhNi from Experimental Example 1 10 / CeO2 was replaced with the cerium oxide-based catalyst Ni / CeO2 prepared in Comparative Example 2, and everything else was the same as in Experimental Example 1.

[0129] In this experimental example, the catalytic activity of the cerium oxide-based catalyst Ni / CeO2 was less than 1 mM / (g catalyst·h).

[0130] Comparative Test Example 3

[0131] Add 1 mmol / L of chloride ions to the chlorate water in Comparative Experiment 1, and otherwise follow the same procedure as in Comparative Experiment 1.

[0132] Figure 6 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate are shown for Experimental Examples 1-3 and Comparative Experimental Examples 1-2. Figure 6It can be seen that the bimetallic cerium oxide-based catalyst exhibits higher catalytic activity in the liquid-phase catalytic hydrogenation reduction of chlorate, significantly outperforming the monometallic cerium oxide-based catalyst. This reflects the crucial role of oxygen vacancy concentration and metal particle dispersion on the catalyst surface in the reaction.

[0133] Figure 7 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate in Experiments 1, 4-6 are shown. Figure 7 It can be seen that the removal rate of chlorate significantly increases with the increase of the amount of bimetallic cerium oxide-based catalyst. The catalytic activity remains essentially constant with increasing amounts of bimetallic cerium oxide-based catalyst, maintaining a range of 21.5–22.5 mM / (g catalyst·h). This indicates that the effect of mass transfer resistance can be neglected during the reaction.

[0134] Figure 8 Figure 1 shows the reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate in Experiments 1, 7-9. Figure 2 shows the reaction curve for the liquid-phase catalytic hydrogenation reduction of chlorate, and Figure 3 shows the linear fitting curve of discrete data between 1 / C0 (C0 is the chlorate concentration) and 1 / r0 (r0 is the reaction rate). Figure 2 shows that the reaction rate of the liquid-phase catalytic hydrogenation reduction of chlorate gradually increases with increasing chlorate concentration. This indicates that a larger amount of chlorate can promote the reaction, consistent with the control mechanism of adsorption reactions. Figure 3 shows that the correlation coefficient R... 2 =0.98, and 1 / C0 and 1 / r0 have a good linear relationship, which conforms to the Langmuir-Hinshelwood model, indicating that adsorption is the rate-determining step of this reaction.

[0135] Figure 9 The reaction curves for the liquid-phase catalytic hydrogenation reduction of chlorate in Examples 1 and 10 are shown. Figure 9 It can be seen that although the catalytic activity of the catalyst is inhibited by adding 5 mmol / L chloride ions to chlorate water, the chlorate removal rate can still reach 100%. This indicates that the bimetallic cerium oxide-based catalyst improves the catalyst's resistance to chloride ion interference through the electronic effect of bimetals.

[0136] Figure 10 To compare the reaction curves of liquid-phase catalytic hydrogenation reduction of chlorate in Experiments 1 and 3. From Figure 10 It can be seen that the catalytic activity of the Rh / CeO2 catalyst decreases significantly due to the influence of chloride ions, indicating that the competitive adsorption of chloride ions at the active sites on the catalyst surface makes the Rh / CeO2 catalyst less resistant to chloride ion interference.

[0137] The cycling test results for the bimetallic cerium oxide-based catalyst are as follows:

[0138] After the reaction in Experiment Example 1 was completed, an equal amount and concentration of chlorate water was added to the reaction system, and the reaction was repeated under the same conditions. This was recorded as one cycle. This process was repeated for a total of four cycles.

[0139] Figure 11 The reaction curve for the cyclic test of Experimental Example 1. Figure 11 It can be seen that after four cycles of testing, the catalytic activity of the bimetallic cerium oxide-based catalyst remained basically unchanged, and the removal rate of chlorate could still reach 100%.

[0140] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a bimetallic cerium oxide-based catalyst in the liquid-phase catalytic hydrogenation reduction of chlorate, characterized in that, A bimetallic cerium oxide-based catalyst was added to chlorate water to carry out a catalytic hydrogenation reaction; The mass-to-volume ratio of the bimetallic cerium oxide-based catalyst to the chlorate water is 0.10–0.25 g: 1 L; The preparation method of the bimetallic cerium oxide-based catalyst includes the following steps: (1) The cerium oxide support was impregnated in a mixed solution of Rh salt and transition metal salt to obtain a catalyst precursor; (2) The catalyst precursor is calcined and reduced sequentially to obtain a bimetallic cerium oxide-based catalyst. The Rh salt in step (1) comprises one or more of Rh(NO3)3, RhCl3 and (NH4)3RhCl6; The transition metal in the transition metal salt is Ni or Co; When the transition metal is Ni, the transition metal salt contains one or more of Ni(CH3COO)2, Ni(CH3COO)2·4H2O and Ni(NO3)2·6H2O; When the transition metal is Co, the transition metal salt contains Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

2. The application according to claim 1, characterized in that, In the mixed solution described in step (1), the concentration of Rh salt is 0.02–0.03 mg / mL, and the concentration of transition metal salt is 0.2–1.5 mg / mL; the volume-to-mass ratio of the mixed solution to the cerium oxide support is 40 mL: 100–500 mg. The impregnation time is 3 to 6 hours; the impregnation is carried out by stirring at a speed of 500 to 1000 rpm.

3. The application according to claim 2, characterized in that, The calcination temperature in step (2) is 300-400℃ and the calcination time is 4-6h; the reduction is carried out by hydrogen reduction, and the flow rate of hydrogen is 10-40mL / min; the reduction temperature is 100-500℃ and the reduction time is 1-2h.

4. The application according to claim 3, characterized in that, The preparation method of the cerium oxide support in step (1) includes the following steps: 1) Ammonia water is added dropwise to Ce(NO3)2·6H2O solution to obtain a mixed solution. The mixed solution reacts to obtain a solid product. 2) The solid products are dried and calcined in sequence to obtain cerium oxide support.

5. The application according to claim 4, characterized in that, Step 1) The concentration of the ammonia solution is 0.1–0.5 mol / L, and the concentration of the Ce(NO3)2·6H2O solution is 0.1–0.5 mol / L; The dripping rate is 2-10 mL / min, and the ammonia dripping is stopped when the pH of the mixed solution is 9-11; The reaction is carried out under stirring at a speed of 500–1000 rpm for 2–4 hours.

6. The application according to claim 5, characterized in that, Step 2) The drying temperature is 80-110℃ and the drying time is 6-14h; the calcination temperature is 400-600℃ and the calcination time is 4-6h.

7. The application of the bimetallic cerium oxide-based catalyst according to claim 1 in the liquid-phase catalytic hydrogenation reduction of chlorate, characterized in that, In the chlorate-containing water, the concentration of chlorate is 0.2–1.0 mmol / L; The temperature of the catalytic hydrogenation reaction is 20–40°C, the reaction time is 1.5–2.5 h, and the hydrogen flow rate is 100–200 mL / min.

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