A sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, its preparation method and application

Abstract

This invention relates to the field of nanocatalytic materials technology, and discloses a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, its preparation method, and its application. The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst contains a support and an active component supported on the support. The active component is Pd and / or Au. The support is formed by calcination of M-Mg-Al ternary hydrotalcite, wherein M is at least one of Fe, Co, Ni, Zn, Cu, and Cr. The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by this invention achieves a space velocity of 5000 h⁻¹. ‑1 Under conditions of a reaction temperature of 280℃, an inlet CO concentration of 5000ppm, and the presence of 50ppm hydrogen sulfide, the CO conversion rate can still be maintained at over 99% after a reaction time of 200h. Furthermore, the catalyst has a simple composition and is promising for industrial application.

Description

Technical Field

[0001] This invention relates to the field of nanocatalytic materials technology, specifically to a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, its preparation method, and its application. Background Technology

[0002] Carbon monoxide is one of the most common air pollutants, primarily originating from the incomplete combustion of carbonaceous materials. Even extremely low concentrations of carbon monoxide can enter the human body through the respiratory tract and cause poisoning. Therefore, controlling the concentration of carbon monoxide in the atmosphere is of great significance for human health and environmental protection.

[0003] In some chemical production processes, the exhaust gas contains low concentrations of CO (<20,000 ppm). Recovery costs for this type of exhaust gas are high. To meet emission requirements, methods such as adsorption, photocatalysis, low-temperature plasma conversion, and combustion are commonly used to remove CO. Among these, catalytic oxidation, which introduces a highly efficient catalyst to lower the combustion temperature, has attracted widespread attention due to its simple process and high removal efficiency.

[0004] Currently, there are many publicly reported catalysts for the catalytic oxidation of low-concentration CO, which typically use noble metals such as Pt, Pd, and Au as active components.

[0005] Meanwhile, hydrotalcite, also known as layered dihydroxy complex metal hydroxide, is a layered material composed of hydroxides of two metals. In recent years, the preparation of supported metal catalysts using the topological transformation method of hydrotalcite layered metal hydroxide structure has become a new hot topic in the utilization of hydrotalcite. Catalytic materials prepared using hydrotalcite as a precursor have also been applied in the carbon monoxide oxidation reaction.

[0006] CN106881110A describes a three-step method for preparing a palladium catalyst suitable for carbon monoxide oxidation in the presence of water vapor. In this catalyst, a palladium precursor is loaded onto the surface of a pre-prepared nickel-aluminum layered double hydroxide via a deposition-precipitation method, followed by liquid-phase reduction with sodium borohydride to obtain metallic palladium particles. This catalyst exhibits good stability in the carbon monoxide oxidation reaction under water vapor coexistence conditions.

[0007] CN107649129A discloses a method for preparing a monolithically structured gold catalyst. In the preparation process, metal oxide-based layered double hydroxide nanosheets are first epitaxially grown on a monolithically structured substrate to form a monolithically structured support. Subsequently, gold nanoparticles are loaded onto this monolithically structured support. This catalyst exhibits good low-temperature activity in the carbon monoxide oxidation reaction.

[0008] However, CO-containing waste gas from many chemical plants typically contains low concentrations of sulfides (<50 ppm, including H2S, COS, etc.) due to the influence of preceding processes. These sulfur compounds have a strong poisoning effect on noble metal catalysts, easily leading to catalyst deactivation. Therefore, developing noble metal catalysts that balance high carbon monoxide oxidation activity with good sulfur resistance has become an important research direction in this field. Summary of the Invention

[0009] The purpose of this invention is to overcome the problem that existing carbon monoxide oxidation catalysts cannot simultaneously achieve high carbon monoxide oxidation activity and good sulfur resistance reaction stability.

[0010] To achieve the above objectives, the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, which contains a support and an active component supported on the support. The active component is Pd and / or Au. The support is formed by calcining M-Mg-Al ternary hydrotalcite, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr, and the Pd and / or Au form alloy particles with the M.

[0011] Based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as metal element, is 0.3-1.2% by weight.

[0012] A second aspect of the present invention provides a method for preparing a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the method comprising the following steps:

[0013] (1) M-Mg-Al ternary hydrotalcite was calcined to obtain a support, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr;

[0014] (2) The carrier is impregnated with an aqueous solution of a noble metal precursor to obtain a solid material;

[0015] (3) The solid material is calcined and crushed in sequence to obtain a powder intermediate with a volume average particle size of not more than 75 μm;

[0016] (4) The powder intermediate is reduced to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst.

[0017] The control conditions are such that, based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as a metal element, in the obtained catalyst is 0.3-1.2% by weight, and the active component is Pd and / or Au.

[0018] The noble metal precursor is sodium tetrachloropalladium and / or chloroauric acid.

[0019] A third aspect of the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst prepared by the method described in the second aspect above.

[0020] The fourth aspect of the present invention provides the application of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst described in the first or third aspect above as a catalyst for carbon monoxide oxidation reaction.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] (1) The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by this invention has a low activation temperature and exhibits good catalytic stability in a hydrogen sulfide-containing atmosphere. Specifically, it exhibits good catalytic stability at a space velocity of 10000 h⁻¹. -1 With a reaction temperature of 250℃, an inlet CO concentration of 6000ppm, and the presence of 50ppm hydrogen sulfide, the CO conversion rate remained above 99% after a reaction time of 200h.

[0023] (2) Compared with other carbon monoxide oxidation catalysts, the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst of the present invention can achieve highly selective oxidation of sulfides (such as H2S) to sulfur dioxide, reduce the adsorption and deposition of sulfides on the catalyst, and extend the catalyst life.

[0024] (3) The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention improves the oxidative catalytic activity of the catalyst; effectively reduces the loading of noble metals on the catalyst and reduces the preparation cost of the catalyst. Attached Figure Description

[0025] Figure 1 This is a conversion diagram of CO oxidation catalytic rate of a preferred sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention;

[0026] Figure 2 This is a SEM image of a preferred sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention.

[0027] Figure 3 This is a TEM image of a preferred sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention. Detailed Implementation

[0028] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] In this invention, unless otherwise specified, the mass percentage of each component constituting the catalyst refers to the mass percentage of the corresponding component relative to the mass of the catalyst. The content of each component in the gas composition used for catalyst reduction in this invention refers to the volume percentage of the corresponding component relative to the total gas volume.

[0031] As previously stated, a first aspect of the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, which contains a support and an active component supported on the support. The active component is Pd and / or Au. The support is formed by calcining M-Mg-Al ternary hydrotalcite, wherein M is at least one of Fe, Co, Ni, Zn, Cu, and Cr, and the Pd and / or Au form alloy particles with the M.

[0032] Based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as metal element, is 0.3-1.2% by weight.

[0033] Preferably, the volume average particle size of the alloy particles is 4-10 nm.

[0034] Preferably, based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of Mg as oxide is 10-45 wt%, the content of Al as oxide is 25-65 wt%, the content of M as oxide is 25-45 wt%, and the content of the active component as metal element is 0.3-1.0 wt%.

[0035] As mentioned above, a second aspect of the present invention provides a method for preparing a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the method comprising the following steps:

[0036] (1) M-Mg-Al ternary hydrotalcite was calcined to obtain a support, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr;

[0037] (2) The carrier is impregnated with an aqueous solution of a noble metal precursor to obtain a solid material;

[0038] (3) The solid material is calcined and crushed in sequence to obtain a powder intermediate with a volume average particle size of not more than 75 μm;

[0039] (4) The powder intermediate is reduced to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst.

[0040] The control conditions are such that, based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as a metal element, in the obtained catalyst is 0.3-1.2% by weight, and the active component is Pd and / or Au.

[0041] The noble metal precursor is sodium tetrachloropalladium and / or chloroauric acid.

[0042] Preferably, the method of the present invention further includes: preparing the M-Mg-Al ternary hydrotalcite by coprecipitation method before calcination in step (1), wherein the operation of the coprecipitation method includes: reacting the metal salt precursor with the precipitant to obtain the M-Mg-Al ternary hydrotalcite;

[0043] The metal salt precursor is a nitrate and / or a chloride.

[0044] According to a preferred embodiment, in the coprecipitation method, the precipitant is a mixture of sodium carbonate and sodium hydroxide or urea.

[0045] In a preferred embodiment, the metal salt precursor in the coprecipitation method is a nitrate.

[0046] Preferably, in step (1), the M-Mg-Al ternary hydrotalcite is represented as follows:

[0047]

[0048] Among them, M 2+ Selected from Mg 2+ Ni 2+ Co 2+ Zn 2+ Cu 2+ At least one of them, M 3+ For Fe 3+ and / or Al 3+ .

[0049] According to a preferred embodiment, the precipitant used in the co-precipitation method is a mixture of sodium carbonate and sodium hydroxide, and

[0050] The molar amount of sodium carbonate used is: [CO3] 2- [Na₂CO₃] = 0.5[Al] 3+];

[0051] The molar amount of sodium hydroxide is: [OH-](NaOH)=2([Ni 2+ ]+[Mg 2+ ]+[Al 3+ ]).

[0052] According to a more preferred embodiment, the precipitant used in the co-precipitation method is a mixture of sodium carbonate and sodium hydroxide, and the operation for preparing the M-Mg-Al ternary hydrotalcite includes:

[0053] S1, mix Al(NO3)3·9H2O, Mg(NO3)2·6H2O and M x+ (NO3) x Dissolve yH2O in 150-500 mL of deionized water to obtain solution A;

[0054] S2. Dissolve Na2CO3 (0.5-1.2 mol / L) and NaOH (1-2 mol / L) in 150-500 mL of deionized water to obtain solution B;

[0055] S3. Under the condition of a rotation speed of 200-400 r / min, use a separatory funnel to add solution A and solution B into a three-necked flask placed in a water bath at 62-68℃ and mix for 20-28 h to obtain a precipitate. During the mixing process, the pH value of the mixed solution is controlled to be maintained at 8-11 by adding NaOH solution (1-2 mol / L).

[0056] S4. Wash the precipitate with deionized water, and then dry it in a forced-air drying oven for 10-15 hours to obtain the M-Mg-Al ternary hydrotalcite.

[0057] According to another preferred embodiment, the precipitant used in the co-precipitation method is urea, and the operation for preparing the M-Mg-Al ternary hydrotalcite includes:

[0058] M x+ (NO3) x ·yH2O, Mg(NO3)2·6H2O, Al(NO3)3·9H2O and urea are dissolved in 300-1000 mL of deionized water to obtain a mixed solution, such that the Mg in the mixed solution is... 2+ 、Al 3+ M x+The total concentration of the three metal cations is 0.1-0.5 mol / L, and the concentration of urea is 2-5 mol / L. The mixed solution is then placed in a water bath at 94-98℃ and stirred vigorously at 200-500 r / min for 20-28 h to obtain a hydrotalcite dispersion. After filtration, the filter residue is washed with deionized water until the pH of the washing liquid is 6.5-7.5. After drying, the M-Mg-Al ternary hydrotalcite is obtained.

[0059] In a preferred embodiment, in step (1), the calcination conditions shall at least satisfy the following: temperature of 200-450°C and time of 3-6 hours.

[0060] According to a preferred embodiment, in step (1), the specific operation of the calcination includes: placing the M-Mg-Al ternary hydrotalcite in the center of a quartz boat, then placing the quartz boat in the center of the heating section of a tubular furnace quartz tube, raising the temperature from room temperature to 200-450°C at a heating rate of 0.5-2°C / min in the presence of Ar and / or N2, calcining at a constant temperature for 3-6 hours, and then sealing and storing after cooling to obtain the carrier.

[0061] In a preferred embodiment, in step (2), the concentration of the aqueous solution of the noble metal precursor is 0.1-0.5 mol / L.

[0062] More preferably, the concentration of the aqueous solution of the noble metal precursor is 0.15-0.4 mol / L.

[0063] Preferably, in step (2), the impregnation treatment includes:

[0064] (21) Disperse the carrier in an aqueous solution of the noble metal precursor to obtain a suspension;

[0065] (22) The suspension with a pH of 5-10 is stirred at 40-90°C for 5-48 hours and then separated to obtain the solid material.

[0066] It should be noted that, in this invention, sodium hydroxide solution (0.4-0.6 mol / L) is used to adjust the pH value of the suspension.

[0067] Preferably, in step (22), the separation includes: filtering the stirred suspension, washing the precipitate with deionized water until the pH value is 6.5-7.5, and then drying it to obtain the solid material.

[0068] According to a preferred embodiment, in step (3), the calcination operation includes: heating the solid material to 400-600°C at a heating rate of 1-3°C / min and calcining for 3-6 hours.

[0069] Preferably, the calcination is carried out in air.

[0070] In step (4), the reduction is carried out in a reducing atmosphere, wherein the hydrogen content is 8-15 vol%.

[0071] Preferably, the reducing atmosphere also contains an inert gas (such as Ar) and / or nitrogen.

[0072] Preferably, in step (4), the reduction conditions must at least satisfy: temperature of 300-500℃ and time of 1-3h.

[0073] Preferably, in the method of the present invention, the control conditions are such that, based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of Mg as oxide is 10-45 wt%, the content of Al as oxide is 25-65 wt%, the content of M as oxide is 25-45 wt%, and the content of the active component as metal element is 0.3-1.0 wt%.

[0074] As previously stated, the third aspect of the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst prepared by the method described in the second aspect above.

[0075] As previously stated, the fourth aspect of the present invention provides the application of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst described in the first or third aspect as a catalyst for the carbon monoxide oxidation reaction.

[0076] Preferably, the reaction gas used in the carbon monoxide oxidation process contains less than 50 ppm of sulfides.

[0077] The following examples further illustrate the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, its preparation method, and its application according to the present invention. The examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0078] In this invention, unless otherwise specified, the ambient temperature or room temperature mentioned in the following examples is 25±5℃.

[0079] Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods in the art.

[0080] Unless otherwise specified, all experimental materials used in the following examples are of analytical grade and are commercially available, for example, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0081] Gas chromatograph: Agilent 8890A, purchased from Agilent Technologies, Inc., USA;

[0082] Fixed-bed microreactor: Model TD-501, purchased from Qingdao Jietian Electrical Equipment Co., Ltd.

[0083] Example 1

[0084] This embodiment illustrates a preferred method for preparing a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention, which is carried out according to the following steps:

[0085] SS1. The M-Mg-Al ternary hydrotalcite was prepared by co-precipitation method using urea as the precipitant:

[0086] 3.22 g of Fe(NO3)3·9H2O, 3.57 g of Mg(NO3)2·6H2O, 8.12 g of Al(NO3)3·9H2O, and 36.0 g of urea were dissolved in 300 mL of deionized water to obtain a mixed solution. The amount of Mg in the mixed solution was... 2+ 、Al 3+ M x+ The total concentration of the three metal cations was 0.14 mol / L, and the concentration of urea was 2.0 mol / L. The mixed solution was then placed in a 96°C water bath and stirred vigorously at 300 r / min for 24 h to obtain a hydrotalcite dispersion. After filtration, the filter residue was washed with deionized water until the pH of the washing liquid was 7. After drying, the M-Mg-Al ternary hydrotalcite was obtained, wherein M is Fe.

[0087] SS2. The M-Mg-Al ternary hydrotalcite is placed in the center of a quartz boat, which is then placed in the center of the quartz tube heating section of a tubular furnace. In the presence of Ar, the temperature is increased from room temperature to 300°C at a rate of 1°C / min, and calcined at a constant temperature for 3 hours. After cooling, it is sealed and stored to obtain the carrier.

[0088] SS3. Disperse 2g of the carrier in 60mL of an aqueous solution (sodium tetrachloropalladium solution) of a noble metal precursor with a concentration of 0.25mol / L to obtain a suspension; then adjust the pH of the suspension to 6.5 using sodium hydroxide solution (0.5mol / L), and stir at 40℃ for 24h. Filter the stirred suspension, take the precipitate, wash it with deionized water until the pH value is 7, and then dry it to obtain the solid material.

[0089] SS4. The solid material is heated to 500°C at a heating rate of 1°C / min, calcined in air for 4 hours, and then crushed to obtain a powder intermediate with a volume average particle size of 75 μm.

[0090] SS5. The powder intermediate was reduced in a tube furnace for 2 hours in a reducing atmosphere (Ar / 10 vol% H2) at 500°C. After cooling to room temperature, the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst was obtained and named P1.

[0091] ICP-OES characterization revealed that, based on its total weight, catalyst P1 contained 13.7 wt% Mg as oxide, 54.2 wt% Al as oxide, 31.4 wt% Fe as oxide, and 0.5 wt% Pd as metal element.

[0092] Figure 2 The SEM image of P1 is shown, from Figure 2 As can be seen, catalyst P1 exhibits a distinct layered structure, indicating that catalyst P1 retained the basic layered structure of hydrotalcite during the synthesis process. Figure 3 A TEM image of P1 is shown, from Figure 3 It can be seen that relatively uniform alloy particles with a volume average particle size of 7 nm were formed on catalyst P1.

[0093] Example 2

[0094] This embodiment uses a similar method to Embodiment 1, except that the types and amounts of some substances differ in step SS1. Specifically, the operation of step SS1 includes:

[0095] 2.24 g of Ni(NO3)2·6H2O, 3.44 g of Mg(NO3)2·6H2O, 7.58 g of Al(NO3)3·9H2O, and 36.0 g of urea were dissolved in 300 mL of deionized water to obtain a mixed solution. The amount of Mg in the mixed solution was... 2+ 、Al 3+ M x+ The total concentration of the three metal cations was 0.13 mol / L, and the concentration of urea was 2.0 mol / L. The mixed solution was then placed in a 96°C water bath and stirred vigorously at 400 r / min for 24 h to obtain a hydrotalcite dispersion. After filtration, the filter residue was washed with deionized water until the pH of the washing liquid was 7. After drying, the M-Mg-Al ternary hydrotalcite was obtained, where M is Ni.

[0096] Furthermore, in step SS2, the constant temperature calcination temperature is 350°C;

[0097] In step SS4, the pH of the suspension is adjusted to 6.0;

[0098] The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst was finally obtained and named P2.

[0099] Characterization by ICP-OES revealed that, based on its total weight, the catalyst P2 contained 13.2% wt% Mg as oxide, 50.7% wt% Al as oxide, 30.0% wt% Ni as oxide, and 0.7% wt% Pd as metal element.

[0100] Relatively uniform alloy particles with a volume average particle size of 8.5 nm were formed on catalyst P2.

[0101] Example 3

[0102] This embodiment uses a similar method to Embodiment 1, except that in step SS1, the M-Mg-Al ternary hydrotalcite is prepared by co-precipitation using Na2CO3 and NaOH as precipitants. The specific operations include:

[0103] S1. Dissolve 2.62g of Co(NO3)2·6H2O, 3.84g of Mg(NO3)2·6H2O and 7.88g of Al(NO3)3·9H2O in 150mL of deionized water to obtain solution A;

[0104] S2. Dissolve 12.75g of Na2CO3 (0.6mol / L) and 6g of NaOH (1.5mol / L) in 150mL of deionized water to obtain solution B;

[0105] S3. Under the condition of 300 r / min rotation speed, use a separatory funnel to add solution A and solution B into a three-necked flask placed in a 65℃ water bath and mix for 24 h to obtain a precipitate. During the mixing process, the pH value of the mixed solution is controlled to be maintained at 10.5 by adding NaOH solution (2 mol / L).

[0106] S4. Wash the precipitate with deionized water and then dry it in a forced-air drying oven for 12 hours to obtain the M-Mg-Al ternary hydrotalcite, wherein M is Co.

[0107] Furthermore, in step SS3, the aqueous solution of the noble metal precursor is a chloroauric acid solution with a concentration of 0.25 mol / L, and some parameters and conditions were modified. Specific operations include:

[0108] SS3. Disperse 2g of the carrier in 60mL of an aqueous solution (chloroauric acid solution) of a noble metal precursor with a concentration of 0.25mol / L to obtain a suspension; then adjust the pH of the suspension to 7.5 using sodium hydroxide solution (0.5mol / L), and stir at 60℃ for 24h. Filter the stirred suspension, take the precipitate, wash it with deionized water until the pH value is 7, and then dry it to obtain the solid material.

[0109] The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst was finally obtained and named P3.

[0110] Characterization by ICP-OES revealed that, based on its total weight, the catalyst P3 contained 14.4% wt% Mg as oxide, 52.3% wt% Al as oxide, 32.4% wt% Co as oxide, and 0.5% wt% Au as metal element.

[0111] Relatively uniform alloy particles with a volume average particle size of 6.2 nm were formed on catalyst P3.

[0112] Comparative Example 1

[0113] This comparative example was conducted using a method similar to that of Example 1, except that in step SS3, Pd was directly loaded using an equal-volume impregnation method. Specifically, the operation of step SS3 includes:

[0114] Saturated water absorption rate determination: 1 g (m1) of the carrier prepared in step SS2 was added to a 5 mL graduated cylinder, compacted on a flat surface, and the volume of the compacted mixture was recorded as 0.8 mL (V1); 2 mL (V2) of water was added, and after thorough stirring, the mixture was allowed to stand for 12 h, and the volume of the mixture was recorded as 2.0 mL (V3); the saturated water absorption rate (ω) of the FeMgAl carrier was calculated to be 0.8 mL / g using the following formula:

[0115]

[0116] Equal volume impregnation: Using the saturated water absorption rate (ω) calculated above, the total volume V of the diluted aqueous solution of the noble metal precursor is calculated using the following formula. t 8mL:

[0117] V t =m 2* ω(mL)

[0118] m2: Mass of the carrier to be impregnated, in grams;

[0119] Weigh out 2.0 mL of an aqueous solution (sodium tetrachloropalladium solution) of the noble metal precursor with a concentration of 0.25 mol / L and add it to a beaker. Add 6.0 mL of deionized water for dilution and stir thoroughly to dissolve. Then add 10 g of the support prepared in step SS2 to be impregnated and stir at room temperature for 0.5 h to impregnate, resulting in a slurry-like mixture. Seal the beaker containing the slurry-like mixture with a sealing film, let it stand in a cool and dry place for 12 h, and then calcine it at a heating rate of 2 °C / min to 500 °C for 2 h to obtain a carbon monoxide oxidation catalyst, named DP1.

[0120] Characterization by ICP-OES revealed that, based on its total weight, the catalyst DP1 contained 14.3 wt% Mg as oxide, 54.7 wt% Al as oxide, 28.3 wt% Fe as oxide, and 2.5 wt% Pd as metal element.

[0121] Comparative Example 2

[0122] This comparative example was conducted using a similar method to Example 1, except that the carrier was prepared using the following method:

[0123] Take 1g of aluminum oxide and calculate its saturated water absorption rate as 0.6mL / g using the method described in Comparative Example 1;

[0124] Subsequently, using magnesium nitrate and ferric nitrate as precursors, a 6 mL precursor solution was prepared (where the magnesium ion concentration was 0.06 mol / L and the ferric ion concentration was 0.07 mol / L). Magnesium and nickel elements were loaded onto 10 g of alumina using the equal volume impregnation method in Comparative Example 1. The loaded product was dried at 80 °C for 6 h and then calcined at 500 °C for 2 h at a heating rate of 2 °C / min to obtain the support.

[0125] The support prepared above is then subjected to the operation in step SS3 to obtain a carbon monoxide oxidation catalyst, named DP2.

[0126] ICP-OES characterization revealed that, based on its total weight, the catalyst DP2 contained 13.2 wt% Mg as oxide, 50.7 wt% Al as oxide, 30.0 wt% Fe as oxide, and 0.69 wt% Pd as metal element.

[0127] Comparative Example 3

[0128] This comparative example was carried out using a similar method to Example 3, except that the support was prepared using the method in Comparative Example 2, and magnesium nitrate and Co(NO3)2·6H2O were used as precursors. A 6 mL precursor solution (with magnesium ion concentration of 0.06 mol / L and cobalt ion concentration of 0.07 mol / L) was prepared and then applied to the operation in step SS3 of Example 3 to obtain a carbon monoxide oxidation catalyst, named DP3.

[0129] ICP-OES characterization revealed that, based on its total weight, the catalyst DP3 contained 14.3 wt% Mg as oxide, 52.1 wt% Al as oxide, 32.5 wt% Co as oxide, and 0.52 wt% Au as metal element.

[0130] Comparative Example 4

[0131] This comparative example was carried out using a similar method to Example 1, except that the supported active metal was Ag, and the aqueous solution of the noble metal precursor used was a silver nitrate solution with a concentration of 0.25 mol / L, resulting in a noble metal-based carbon monoxide oxidation catalyst named DP4.

[0132] Characterization by ICP-OES revealed that, based on its total weight, the catalyst DP4 contained 13.7 wt% Mg as oxide, 54.2 wt% Al as oxide, 31.4 wt% Fe as oxide, and 0.5 wt% Ag as metal element.

[0133] Comparative Example 5

[0134] This comparative example was carried out using a similar method to Example 1, except that the aqueous solution of the noble metal precursor used was a sodium tetrachloropalladium solution with a concentration of 0.1 mol / L, to obtain a noble metal-based carbon monoxide oxidation catalyst, named DP5.

[0135] Characterization by ICP-OES revealed that, based on its total weight, the catalyst DP5 contained 13.7 wt% Mg as oxide, 54.4 wt% Al as oxide, 31.5 wt% Fe as oxide, and 0.15 wt% active metal Pd as metal element.

[0136] Test Example 1

[0137] The catalyst prepared in the above example was placed in a fixed-bed microreactor (reaction tube inner diameter of 6 mm), and heated to 280 °C at a heating rate of 5 °C / min. The catalyst was then subjected to a catalytic oxidation reaction with the feed gas for 200 h.

[0138] The composition of the reactant gas was: 0.5 vol% CO (CO), 0.005 vol% H2S, 5 vol% O2, and 94.495 vol% CO2, with a reaction space velocity of 5000 h⁻¹. -1 .

[0139] The concentration of CO at the reactor outlet (Ct) was detected by gas chromatography at time t. t The CO conversion rate is calculated using the following formula: CO conversion rate t / % = (C t- C0) / C0*100%;

[0140] The CO conversion rate of product P1 was monitored over 200 hours, and the results are shown in [reference]. Figure 1 ;from Figure 1 It can be seen that during the long-term carbon monoxide oxidation reaction of 200h, the carbon monoxide conversion rate of P1 can be maintained at over 99%.

[0141] The CO conversion rate after reacting at 280℃ for 200 h was calculated for the catalysts prepared in the above examples, and the results are shown in Table 1.

[0142] Table 1

[0143]

[0144] As can be seen from the above, the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by this invention has a space velocity of 5000 h⁻¹. -1 Under conditions of a reaction temperature of 280℃, an inlet CO concentration of 5000ppm, and the presence of 50ppm hydrogen sulfide, the CO conversion rate can still be maintained at over 99% after a reaction time of 200h. Furthermore, the catalyst has a simple composition and is promising for industrial application.

[0145] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, characterized in that, This sulfur-resistant noble metal-based carbon monoxide oxidation catalyst contains a support and an active component supported on the support. The active component is Pd and / or Au. The support is formed by calcination of M-Mg-Al ternary hydrotalcite, wherein M is at least one of Fe, Co, Ni, Zn, Cu, and Cr, and the Pd and / or Au form alloy particles with the M. The volume average particle size of the alloy particles is 4-10 nm. Based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as metal element, is 0.3-1.2% by weight. The impregnation process involves dispersing the carrier in an aqueous solution of a noble metal precursor to obtain a suspension, and controlling the conditions so that the pH of the suspension is 5-10.

2. The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst according to claim 1, wherein, Based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst (100% by weight), the content of Mg as oxide is 10-45% by weight, the content of Al as oxide is 25-65% by weight, the content of M as oxide is 25-45% by weight, and the content of the active component as metal element is 0.3-1.0% by weight.

3. A method for preparing a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, characterized in that, The method includes the following steps: (1) M-Mg-Al ternary hydrotalcite was calcined to obtain a support, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr; (2) The carrier is impregnated with an aqueous solution of a noble metal precursor to obtain a solid material; (3) The solid material is calcined and crushed in sequence to obtain a powder intermediate with a volume average particle size of not more than 75 μm; (4) The powder intermediate is reduced to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst; The control conditions are such that, based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component, calculated as a metal element, in the obtained catalyst is 0.3-1.2% by weight, and the active component is Pd and / or Au. The noble metal precursor is sodium tetrachloropalladium and / or chloroauric acid. In step (2), the impregnation process includes: (21) Disperse the carrier in an aqueous solution of the noble metal precursor to obtain a suspension; (22) The suspension with a pH of 5-10 is stirred at 40-90°C for 5-48 hours and then separated to obtain the solid material.

4. The method according to claim 3, wherein, The method further includes: preparing the M-Mg-Al ternary hydrotalcite by coprecipitation method before calcination in step (1), wherein the operation of coprecipitation method includes: contacting the metal salt precursor with the precipitant to obtain the M-Mg-Al ternary hydrotalcite; The metal salt precursor is a nitrate and / or a chloride.

5. The method according to claim 4, wherein, The precipitant is a mixture of sodium carbonate and sodium hydroxide or urea.

6. The method according to claim 4 or 5, wherein, The metal salt precursor is a nitrate.

7. The method according to claim 3, wherein, In step (1), the calcination conditions must at least meet the following requirements: temperature of 200-450℃ and time of 3-6h.

8. The method according to claim 3, wherein, In step (2), the concentration of the aqueous solution of the noble metal precursor is 0.1-0.5 mol / L.

9. The method according to claim 3, wherein, In step (2), the concentration of the aqueous solution of the noble metal precursor is 0.15-0.4 mol / L.

10. The method according to claim 3, wherein, In step (3), the calcination operation includes: heating the solid material to 400-600℃ at a heating rate of 1-3℃ / min and calcining for 3-6 hours.

11. The method according to claim 3, wherein, In step (4), the reduction is carried out in a reducing atmosphere, wherein the hydrogen content is 8-15 vol.

12. The method according to claim 3, wherein, In step (4), the reduction conditions must at least be met: temperature of 300-500℃ and time of 1-3h.

13. A sulfur-resistant noble metal-based carbon monoxide oxidation catalyst prepared by the method according to any one of claims 3-12.

14. The application of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst according to claim 1, 2 or 13 as a catalyst for carbon monoxide oxidation reaction.

15. The application according to claim 14, wherein, The reaction gas used in the carbon monoxide oxidation process contains less than 50 ppm of sulfides.

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