Bimetal cerium oxide-based catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of sewage treatment, and provides a bimetallic cerium oxide-based catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: dipping a cerium oxide carrier in a mixed solution of Rh salt and transition metal salt to obtain a catalyst precursor; and sequentially roasting and reducing the catalyst precursor to obtain the bimetallic cerium oxide-based catalyst. Compared with a monometal catalyst, the bimetallic cerium oxide-based catalyst provided by the invention has abundant active sites, and the activity of the catalyst is effectively improved by the synergistic effect of bimetallic; the Rh metal particles are uniformly dispersed, the electron effect of bimetal is beneficial to formation of oxygen vacancies on the surface of the carrier, the electron structure can be mutually adjusted, and meanwhile, good chloride ion interference resistance is achieved; the preparation method is simple and easy to operate, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a bimetallic cerium oxide-based catalyst and a preparation method and application thereof. Background Art

[0002] In the use of chlorine-containing disinfectants and the electrolysis process of chlor-alkali industry, toxic substances such as chlorate (ClO3 - ). If the human body ingests too much chlorate, it will damage the digestive system and central nervous system, and increase the burden on the kidneys; chlorate, as a strong oxidative byproduct, has a negative impact on industrial production processes and is also a potential lasting hazard to the environment. For the above reasons, the World Health Organization has set the temporary guidance value for chlorate concentration in drinking water at 70μg / L (about 8.3μM), so effective control of chlorate emissions is of great significance to sustainable development and environmental protection.

[0003] For drinking water, common chlorate treatment methods include biological reduction, adsorption, and catalytic reduction. Although the biological reduction method does not produce secondary waste and has a low treatment cost, the microbial adsorption and reduction have low selectivity for chlorate, and the treatment effect is unstable. The adsorption method mainly uses activated carbon adsorption, which faces the problem of regeneration of activated carbon after adsorption saturation. In the chlor-alkali industrial electrolysis process, chlorate as a by-product will reduce the electrolysis efficiency. In order to remove the accumulated chlorate in the system, direct discharge or chemical removal methods are generally adopted. Although the direct discharge method is fast and effective for industrial applications, the discharged wastewater causes harm to the water environment. The chemical removal method is to add a large amount of hydrochloric acid into the electrolysis system to neutralize the OH - However, this method must be carried out at high temperature, and the input of a large amount of hydrochloric acid increases the degree of corrosion to the equipment.

[0004] Liquid-phase catalytic hydrogenation reduction is a reduction reaction that is carried out at room temperature and pressure by dispersing a solid catalyst in a pollutant solution and using hydrogen as a reducing agent. It has the advantages of being easy to operate, efficient and clean. The commonly used catalyst for liquid-phase catalytic hydrogenation reduction is a supported catalyst. Currently, the supported single metal catalyst has an unsatisfactory effect on the liquid-phase catalytic hydrogenation reduction of chlorates. At the same time, the product (Cl - ) on the catalyst surface causes the problem of catalyst poisoning. Studies have shown that Rh-based catalysts have high hydrogenation reduction activity. The addition of non-precious metals may change the electronic structure of Rh and promote the product (Cl - ), but there is little research in this direction.

[0005] Therefore, a bimetallic cerium oxide-based catalyst was developed to effectively avoid the Cl -It can be used to poison catalysts caused by adsorption and stably remove chlorates, and has good application prospects. Summary of the invention

[0006] The purpose of the present invention is to provide a bimetallic cerium oxide-based catalyst and a preparation method and application thereof in view of the deficiencies in the prior art.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

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

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

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

[0011] Preferably, in the mixed solution of 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 mass ratio of the mixed solution to the cerium oxide carrier is 40 mL: 100-500 mg;

[0012] The immersion time is 3 to 6 hours; the immersion is carried out during stirring, and the stirring speed is 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 comprises 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 includes Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

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

[0018] Preferably, the method for preparing the cerium oxide carrier in step (1) comprises the following steps:

[0019] 1) adding ammonia water dropwise to a Ce(NO3)2·6H2O solution to obtain a mixed solution, and reacting the mixed solution to obtain a solid product;

[0020] 2) The solid product is dried and calcined in sequence to obtain a cerium oxide carrier.

[0021] Preferably, the concentration of the ammonia water 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 dropping speed is 2-10 mL / min, and the dropping of ammonia water is stopped when the pH value of the mixed solution is 9-11;

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

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

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

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

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

[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 time of the catalytic hydrogenation reaction is 1.5-2.5 hours, and the hydrogen flow rate of the catalytic hydrogenation reaction is 100-200 mL / min.

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

[0031] 1) Compared with the monometallic catalyst, the bimetallic cerium oxide-based catalyst of the present invention has abundant active sites, and the synergistic effect of the bimetallic effectively improves the activity of the catalyst; the Rh metal particles are evenly dispersed, and the electronic effect of the bimetallic is conducive to the formation of oxygen vacancies on the carrier surface, which can mutually regulate the electronic structure and has 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] Figure 2 The 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, wherein Figure (a) is the Raman spectra at wave numbers 300 to 1500 cm -1 Raman spectrum, Figure (b) is the wave number 200 ~ 600cm -1 Raman spectrum of

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

[0037] Figure 5 X-ray photoelectron spectra of cerium oxide-based catalysts prepared in Example 1 and Comparative Examples 1 and 2, wherein Figure (a) is the X-ray photoelectron spectrum of Ce 3d, Figure (b) is the X-ray photoelectron spectrum of O1s, 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 of liquid phase catalytic hydrogenation reduction of chlorate in Test Examples 1 to 3 and Comparative Test Examples 1 to 2;

[0039] Figure 7 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1, 4 to 6;

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

[0041] Fig. 9 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in Test Examples 1 and 10;

[0042] Fig.10 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in comparative test examples 1 and 3;

[0043] Fig.11 This is the reaction curve of the cycle test in Test Example 1. DETAILED DESCRIPTION

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

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

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

[0047] In the present invention, in the mixed solution of step (1), the concentration of Rh salt is preferably 0.02-0.03 mg / mL, more preferably 0.022-0.028 mg / mL, and 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 more preferably 0.5-1 mg / mL; the volume mass ratio of the mixed solution to the cerium oxide carrier is preferably 40 mL: 100-500 mg, more preferably 40 mL: 200-400 mg, and more preferably 40 mL: 300 mg;

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

[0049] In the present invention, after the impregnation in step (1), the catalyst precursor is preferably evaporated to dryness, and the evaporation temperature is preferably 80-90° C., more preferably 85° C.; the evaporation time is preferably 1-2 h, more preferably 1.5 h.

[0050] In the present invention, the Rh salt in step (1) preferably comprises 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 comprises 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 comprises Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

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

[0055] In the present invention, the method for preparing the cerium oxide carrier in step (1) preferably comprises the following steps:

[0056] 1) adding ammonia water dropwise to a Ce(NO3)2·6H2O solution to obtain a mixed solution, and reacting the mixed solution to obtain a solid product;

[0057] 2) The solid product is dried and calcined in sequence to obtain a cerium oxide carrier.

[0058] In the present invention, the concentration of the ammonia water in step 1) is preferably 0.1-0.5 mol / L, more preferably 0.2-0.4 mol / L, and 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 more preferably 0.3 mol / L;

[0059] The dripping speed is preferably 2 to 10 mL / min, more preferably 4 to 8 mL / min, and more preferably 6 mL / min; the dripping of ammonia water is stopped when the pH value of the mixed solution is preferably 9 to 11, more preferably 9.5 to 10.5, and more preferably 10;

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

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

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

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

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

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

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

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

[0068] Example 1

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

[0070] Prepare a mixed aqueous solution of Rh(NO3)3 and Ni(NO3)2·6H2O, wherein the concentration of Rh(NO3)3 is 0.025 mg / mL and the concentration of Ni(NO3)2·6H2O is 1.25 mg / mL. Immerse 100 mg of cerium oxide support in 40 mL of the mixed aqueous solution for 4 h (stir the mixed solution at 700 rpm during the immersion process) to obtain a catalyst precursor solution. Evaporate the catalyst precursor solution at 85°C for 1.5 h to obtain a catalyst precursor.

[0071] The catalyst precursor was placed in a muffle furnace, calcined at 300° C. for 4 h, and then reduced at 200° C. for 2 h in hydrogen with 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 example is labeled as 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 Example 1.

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

[0076] Example 3

[0077] The Ni(NO3)2·6H2O in the mixed aqueous solution of Example 1 was replaced by Co(NO3)2·6H2O, and the rest was the same as Example 1.

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

[0079] Example 4

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

[0081] Prepare a mixed aqueous solution of RhCl3 and Ni(CH3COO)2, wherein the concentration of RhCl3 is 0.03 mg / mL and the concentration of Ni(CH3COO)2 is 0.5 mg / mL. Place 300 mg of cerium oxide support in 40 mL of the mixed aqueous solution and immerse for 6 hours (stir the mixed solution at a speed of 500 rpm during the immersion process) to obtain a catalyst precursor solution. Evaporate the catalyst precursor solution at 80°C for 2 hours to obtain a catalyst precursor.

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

[0083] Example 5

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

[0085] Prepare a mixed aqueous solution of (NH4)3RhCl6 and Ni(CH3COO)2·4H2O, wherein the concentration of (NH4)3RhCl6 is 0.02 mg / mL and the concentration of Ni(CH3COO)2·4H2O is 1.25 mg / mL. Immerse 500 mg of cerium oxide support in 40 mL of the mixed aqueous solution for 3 h (stir the mixed solution at 1000 rpm during the immersion process) to obtain a catalyst precursor solution. Evaporate the catalyst precursor solution at 90°C for 1 h to obtain a catalyst precursor.

[0086] The catalyst precursor was placed in a muffle furnace, calcined at 400° C. for 6 h, and then reduced at 500° C. for 1 h in hydrogen with 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 marked as 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 having 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 marked as Ni / CeO2.

[0093] Figure 1 TEM images of the cerium oxide-based catalysts prepared in Examples 1 and 2 and Comparative Example 1. Figure 1It can be seen that the bimetallic cerium oxide-based catalysts of Examples 1 and 2 have obvious cerium oxide support morphology, and the lattice fringes of the Ce crystal (111) and Ni crystal (111) planes can be clearly seen; there is a covering layer around the Ni particles, and the covering layer is amorphous cerium oxide. The formation of the covering layer is related to the strong interaction between the metal and the support. The monometallic cerium oxide-based catalyst of Comparative Example 1 has obvious 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 The 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 are shown in FIG. 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. After loading metal, CeO2 still shows the characteristic peaks of cerium phase with good crystal form. 10 A characteristic peak at 44.6° belonging to the Ni(111) crystal plane was observed in the spectra of / CeO2 and Ni / CeO2. Since the Rh concentration was lower than the detection limit of the XRD technology or the particle size of the Rh nanoparticles was small, no Rh phase was detected in all Rh-containing catalysts.

[0095] Figure 3 The Raman spectra of the cerium oxide-based catalysts prepared in Examples 1, 2 and Comparative Example 1, wherein Figure (a) is the Raman spectra at wave numbers 300 to 1500 cm -1 Raman spectrum, Figure (b) is the wave number 200 ~ 600cm -1 Raman spectrum of Figure 3 It can be seen that the single metal cerium oxide-based catalyst of Comparative Example 1 has a -1 A strong peak appears at 595cm -1 There are weak peaks at 595 cm-1 and 596 cm-2, which are respectively attributed to the vibration mode of cerium oxide with fluorite-type cubic structure and the defect-induced mode of oxygen vacancies in the cerium structure. -1 The band near 456 cm -1 There is no obvious change in the band intensity at . This indicates that the interaction between the bimetallic Rh and Ni occurs on the surface of cerium oxide. Figure 3 As can be seen in the middle figure (b), the main peak of Rh / CeO2 shifts to a lower wave number after the introduction of Ni, and the shift increases with the increase of Ni content, indicating that the bimetallic RhNi 10 / CeO2 catalyst has more oxygen vacancies.

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

[0097] Figure 5 X-ray photoelectron spectra of the cerium oxide-based catalysts prepared in Example 1 and Comparative Examples 1 and 2. Among them, Figure (a) 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. It can be seen from Figure 5 that for the Ce content, Rh / CeO2 < RhNi 10 / CeO2 < Ni / CeO2, indicating that compared with the monometallic cerium oxide-based catalyst Rh / CeO2, the doping of Ni stabilizes the electronic structure of cerium oxide. For oxygen, the monometallic cerium oxide-based catalyst Ni / CeO2 has the highest oxygen vacancy concentration on the surface, followed by the bimetallic cerium oxide-based catalyst, and the monometallic cerium oxide-based catalyst Rh / CeO2 is the lowest. It can be seen that the doping of Ni effectively stabilizes the oxygen vacancies on the catalyst surface. For the metal particles, due to the interaction between the bimetals, the metal particles change. The Ni content in the bimetallic cerium oxide-based catalyst is higher than that in the monometallic cerium oxide-based catalyst Ni / CeO2, while the Rh content is lower than that in the monometallic cerium oxide-based catalyst Rh / CeO2. Ni not only transfers electrons to the cerium oxide support but also has an electron transfer with Rh, weakening the interaction between Rh and the cerium oxide support.

[0098] Test Example 1

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

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

[0101] Test Example 2

[0102] The bimetallic cerium oxide-based catalyst RhNi 10 / CeO2 is replaced by the bimetallic cerium oxide-based catalyst RhNi2 / CeO2 prepared in Example 2, and the rest is the same as in Experimental Example 1.

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

[0104] Test Example 3

[0105] The bimetallic cerium oxide-based catalyst RhNi 10 / CeO2 is replaced by the bimetallic cerium oxide-based catalyst RhCo / CeO2 prepared in Example 3, and the rest is the same as in Experimental Example 1.

[0106] In this test 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 volume ratio of the bimetallic cerium oxide-based catalyst and the chlorate water in Experimental Example 1 was modified to 0.1 g:1 L, and the rest was the same as Experimental Example 1.

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

[0110] Test Example 5

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

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

[0113] Test Example 6

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

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

[0116] Test Example 7

[0117] The concentration of chlorate water in Test Example 1 was modified to 0.25 mmol / L, and the rest was the same as Test Example 1.

[0118] Test Example 8

[0119] The concentration of chlorate water in Test Example 1 was modified to 0.6 mmol / L, and the rest was the same as Test Example 1.

[0120] Test Example 9

[0121] The concentration of chlorate water in Test Example 1 was modified to 1.0 mmol / L, and the rest was the same as Test Example 1.

[0122] Test Example 10

[0123] 5 mmol / L of chloride ions was added to the chlorate water of Test Example 1, and the rest was the same as Test Example 1.

[0124] Comparative test example 1

[0125] The bimetallic cerium oxide-based catalyst RhNi 10 / CeO2 is replaced by the cerium oxide-based catalyst Rh / CeO2 prepared in Comparative Example 1, and the rest is the same as in Experimental Example 1.

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

[0127] Comparative Test Example 2

[0128] The bimetallic cerium oxide-based catalyst RhNi 10 / CeO2 is replaced by the cerium oxide-based catalyst Ni / CeO2 prepared in Comparative Example 2, and the rest is the same as in Experimental Example 1.

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

[0130] Comparative Test Example 3

[0131] 1 mmol / L of chloride ions was added to the chlorate water of Comparative Test Example 1, and the rest was the same as Comparative Test Example 1.

[0132] Figure 6 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in Test Examples 1 to 3 and Comparative Test Examples 1 to 2 are shown in FIG. Figure 6It can be seen that the bimetallic cerium oxide-based catalyst has a higher catalytic activity in the liquid phase catalytic hydrogenation reduction of chlorate, which is significantly better than the monometallic cerium oxide-based catalyst. This also reflects that the oxygen vacancy concentration on the catalyst surface and the dispersion of metal particles play a key role in the reaction.

[0133] Figure 7 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1, 4 to 6 are shown in FIG. Figure 7 It can be seen that with the increase in the amount of bimetallic cerium oxide-based catalyst, the removal rate of chlorate is significantly improved. With the increase in the amount of bimetallic cerium oxide-based catalyst, its catalytic activity is basically the same, maintained at 21.5-22.5mM / (g catalyst·h). This shows that the influence of mass transfer resistance can be ignored during the reaction process.

[0134] Figure 8 The reaction diagrams of the liquid-phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1, 7 to 9, wherein Figure (a) is the reaction curve of the liquid-phase catalytic hydrogenation reduction of chlorate, and Figure (b) is the discrete data linear fitting curve of 1 / C0 (C0 is the chlorate concentration) and 1 / r0 (r0 is the reaction rate). It can be seen from Figure (a) that with the increase of chlorate concentration, the reaction rate of the liquid-phase catalytic hydrogenation reduction of chlorate gradually accelerates. This indicates that more chlorate can promote the reaction, which is consistent with the control mechanism of the adsorption reaction. It can be seen from Figure (b) that the correlation coefficient R 2 =0.98, 1 / C0 and 1 / r0 have a good linear relationship, which is consistent with the Langmuir-Hinshelwood model, indicating that adsorption is the controlling step of the reaction rate.

[0135] Fig. 9 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in Experimental Examples 1 and 10 are shown in FIG. Fig. 9 It can be seen that when 5mmol / L chloride ions are added to the chlorate water, the catalytic activity of the catalyst is inhibited, but the removal rate of chlorate can still reach 100%, indicating that the bimetallic cerium oxide-based catalyst improves the anti-interference of the catalyst to chloride ions by virtue of the electronic effect of the bimetal.

[0136] Fig.10 The reaction curves of liquid phase catalytic hydrogenation reduction of chlorate in comparative test examples 1 and 3 are shown in FIG. Fig.10 It can be seen that the catalytic activity of the Rh / CeO2 catalyst is greatly reduced by the influence of chloride ions, indicating that the competitive adsorption of chloride ions on the active sites on the catalyst surface makes the Rh / CeO2 catalyst less resistant to chloride ions.

[0137] The cyclic test of the bimetallic ceria-based catalyst is as follows:

[0138] After the reaction of Test Example 1 was completed, an equal amount of chlorate water of equal concentration was added to the reaction system, and the reaction was repeated under the same conditions, which was recorded as one cycle test. Similarly, a total of four cycle tests were performed.

[0139] Fig.11 This is the reaction curve of the cycle test of Test Example 1. Fig.11 It can be seen that after four cycles of testing, the catalytic activity of the bimetallic cerium oxide-based catalyst remains basically unchanged, and the removal rate of chlorate can still reach 100%.

[0140] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a bimetallic cerium oxide-based catalyst, characterized in that: The following steps are included: (1) impregnating a cerium oxide support in a mixed solution of a Rh salt and a transition metal salt to obtain a catalyst precursor; (2) The catalyst precursor is calcined and reduced in sequence to obtain a bimetallic cerium oxide-based catalyst.

2. The preparation method according to claim 1, characterized in that: In the mixed solution of 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 mass ratio of the mixed solution to the cerium oxide carrier is 40 mL: 100-500 mg; The immersion time is 3 to 6 hours; the immersion is carried out during stirring, and the stirring speed is 500 to 1000 rpm.

3. The preparation method according to claim 1 or 2, characterized in that: 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 comprises 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 includes Co(CH3COO)2·4H2O or Co(NO3)2·6H2O.

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

5. The preparation method according to claim 4, characterized in that: The preparation method of the cerium oxide carrier in step (1) comprises the following steps: 1) adding ammonia water dropwise to a Ce(NO3)2·6H2O solution to obtain a mixed solution, and reacting the mixed solution to obtain a solid product; 2) The solid product is dried and calcined in sequence to obtain a cerium oxide carrier.

6. The preparation method according to claim 5, characterized in that: Step 1) The concentration of the ammonia water 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 dropping speed is 2-10 mL / min, and the dropping of ammonia water is stopped when the pH value of the mixed solution is 9-11; The reaction is carried out under stirring at a speed of 500 to 1000 rpm for a time of 2 to 4 hours.

7. The preparation method according to claim 5 or 6, characterized in that: Step 2) The drying temperature is 80-110° C., and the drying time is 6-14 hours; the calcining temperature is 400-600° C., and the calcining time is 4-6 hours.

8. A bimetallic cerium oxide-based catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the bimetallic cerium oxide-based catalyst according to claim 8 in liquid phase catalytic hydrogenation reduction of chlorate, characterized in that: A bimetallic cerium oxide-based catalyst is added to a chlorate water body to carry out a catalytic hydrogenation reaction; The mass volume ratio of the bimetallic cerium oxide-based catalyst to the chlorate water is 0.10-0.25 g:1L.

10. Use of the bimetallic cerium oxide-based catalyst according to claim 9 in liquid phase catalytic hydrogenation reduction of chlorate, characterized in that: In the chlorate water, the concentration of chlorate is 0.2-1.0 mmol / L; The temperature of the catalytic hydrogenation reaction is 20-40° C., the time of the catalytic hydrogenation reaction is 1.5-2.5 hours, and the hydrogen flow rate of the catalytic hydrogenation reaction is 100-200 mL / min.

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