Sulfur-tolerant noble metal-based carbon monoxide oxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of nano catalytic materials, and discloses a sulfur-tolerant noble metal-based carbon monoxide oxidation catalyst and a preparation method and application thereof.The sulfur-tolerant noble metal-based carbon monoxide oxidation catalyst contains a carrier and an active component loaded on the carrier, the active component is Pd and / or Au, and the active component is one or more selected from the group consisting of Pd and Au. The carrier is formed by roasting M-Mg-Al ternary hydrotalcite, and M is at least one of Fe, Co, Ni, Zn, Cu and Cr. According to the sulfur-tolerant noble metal-based carbon monoxide oxidation catalyst provided by the invention, the CO conversion rate can still be maintained at 99% or above after the reaction time of 200 hours in the presence of hydrogen sulfide with the air speed of 5000h <-1 >, the reaction temperature of 280 DEG C, the imported CO concentration of 5000ppm and 50ppm, and the catalyst is simple in composition and has an industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of nanocatalytic materials, and in particular to a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst and a preparation method and application thereof. Background Art

[0002] Carbon monoxide is one of the common pollutants in the atmosphere. Its main source is the product of incomplete combustion of carbon-containing substances. Even very 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 to human survival, health and environmental protection.

[0003] In some chemical production processes, the tail gas produced contains low concentration of CO gas (<20000ppm). For this type of tail gas, the recovery cost is high. In order to meet the emission requirements, adsorption, photocatalysis, low-temperature plasma conversion, combustion and other methods are usually used to remove CO. Among them, the catalytic oxidation method introduces a high-efficiency catalyst on the basis of the combustion method to reduce the temperature of the combustion process. It has the advantages of simple process and high removal efficiency, and therefore has received widespread attention.

[0004] At present, there have been many public reports on catalysts for the catalytic oxidation of low-concentration CO, which usually use precious metals such as Pt, Pd, and Au as active components.

[0005] At the same time, hydrotalcite, also known as layered dihydroxy composite metal hydroxide, is a layered material composed of two metal hydroxides. In recent years, the preparation of supported metal catalysts by the topological transformation method of hydrotalcite layered metal hydroxide structure has become a new hot spot for the utilization of hydrotalcite. Catalytic materials prepared with hydrotalcite as a precursor have also been used in carbon monoxide oxidation reactions.

[0006] CN106881110A adopts a three-step method of coprecipitation-deposition precipitation-liquid phase reduction to prepare a palladium catalyst suitable for carbon monoxide oxidation in the coexistence of water vapor. In the catalyst, the palladium precursor is loaded on the surface of the pre-prepared nickel-aluminum hydrotalcite by a deposition precipitation method, and then the metal palladium particles are obtained by a sodium borohydride liquid phase reduction method. The catalyst shows good stability in the carbon monoxide oxidation reaction under the coexistence of water vapor.

[0007] CN107649129A discloses a method for preparing a monolithic gold catalyst. In the preparation process of the monolithic gold catalyst, a metal oxide hydrotalcite nanosheet layer is firstly epitaxially grown on the monolithic substrate to form a monolithic support, and then nano-gold particles are loaded on the monolithic support. The catalyst exhibits good low-temperature activity in the carbon monoxide oxidation reaction.

[0008] However, CO-containing waste gas from many chemical plants usually contains low concentrations of sulfides (<50ppm, including H2S, COS, etc.) due to the influence of previous processes. Such sulfur-containing compounds have a strong poisoning effect on precious metal catalysts and can easily lead to catalyst deactivation. Therefore, the development of precious metal catalysts that have both high carbon monoxide oxidation activity and good sulfur-resistant reaction stability has become an important research direction in this field. Summary of the invention

[0009] The purpose of the present invention is to overcome the problem that the carbon monoxide oxidation catalyst in the prior art cannot have both high carbon monoxide oxidation activity and good sulfur resistance reaction stability.

[0010] In order to achieve the above-mentioned object, the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst on one hand, wherein the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst comprises a carrier and an active component supported on the carrier, wherein the active component is Pd and / or Au, and the carrier 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 the 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 in terms of 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) calcining M-Mg-Al ternary hydrotalcite to obtain a carrier, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr;

[0014] (2) impregnating the support with an aqueous solution of a noble metal precursor to obtain a solid material;

[0015] (3) calcining and crushing the solid material in sequence to obtain a powder intermediate having a volume average particle size of no more than 75 μm;

[0016] (4) reducing the powder intermediate to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst;

[0017] The conditions are controlled so that in the obtained sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of active components in terms of metal elements is 0.3-1.2% by weight based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, and the active components are Pd and / or Au;

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

[0019] 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.

[0020] The fourth aspect of the present invention provides the use of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst described in the first aspect or the third aspect as a catalyst for a 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 the present invention has a low activation temperature and exhibits good catalytic stability in a hydrogen sulfide-containing atmosphere. Specifically, at a space velocity of 10000 h -1 , reaction temperature 250℃, inlet CO concentration 6000ppm and 50ppm hydrogen sulfide, after 200h reaction time, CO conversion rate still maintained above 99%;

[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 amount of the noble metal of the catalyst, and reduces the preparation cost of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the conversion rate of CO catalytically oxidized by 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 DESCRIPTION

[0028] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0029] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

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

[0031] As mentioned above, the first aspect of the present invention provides a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, which contains a carrier and an active component supported on the carrier, wherein the active component is Pd and / or Au, and the carrier 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 in terms of 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 precious metal-based carbon monoxide oxidation catalyst, 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.

[0035] As mentioned above, the 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) calcining M-Mg-Al ternary hydrotalcite to obtain a carrier, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr;

[0037] (2) impregnating the support with an aqueous solution of a noble metal precursor to obtain a solid material;

[0038] (3) calcining and crushing the solid material in sequence to obtain a powder intermediate having a volume average particle size of no more than 75 μm;

[0039] (4) reducing the powder intermediate to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst;

[0040] The conditions are controlled so that in the obtained sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of active components in terms of metal elements is 0.3-1.2% by weight based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, and the active components are Pd and / or Au;

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

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

[0043] Wherein, the metal salt precursor is nitrate and / or 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] Preferably, in the coprecipitation method, the metal salt precursor 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 M 3+ Fe 3+ and / or Al 3+ .

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

[0050] The molar dosage of the sodium carbonate 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 coprecipitation method is a mixture of sodium carbonate and sodium hydroxide, and the operation of preparing the M-Mg-Al ternary hydrotalcite includes:

[0053] S1, 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, dissolving 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. At a rotation speed of 200-400 r / min, solution A and solution B were added into a three-necked flask placed in a water bath at 62-68° C. using a separatory funnel and mixed for 20-28 hours to obtain a precipitate. During the mixing process, the pH value of the mixed solution was controlled to be maintained at 8-11 by dropwise addition of 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 coprecipitation method is urea, and the operation of 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 300-1000mL of deionized water to obtain a mixed solution, so that Mg in the mixed solution 2+ 、Al 3+ 、M x+The total concentration of the three types of metal cations is 0.1-0.5 mol / L, the concentration of urea is 2-5 mol / L, and the mixed solution is then placed in a 94-98°C water bath and vigorously stirred at a speed of 200-500 r / min for 20-28 hours to obtain a hydrotalcite dispersion. After filtering, the filter residue is washed with deionized water until the pH value of the eluate is 6.5-7.5, and the M-Mg-Al ternary hydrotalcite is obtained after drying.

[0059] Preferably, in step (1), the calcination conditions at least meet the following conditions: temperature of 200-450° C. and time of 3-6 h.

[0060] According to a preferred embodiment, in step (1), the specific operation of calcination includes: placing the M-Mg-Al ternary hydrotalcite in the center of a quartz boat, and then placing the quartz boat in the center of a quartz tube heating section of a tubular furnace, heating 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 3-6h, and sealing and storing after cooling to obtain the carrier.

[0061] Preferably, 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 operation of the immersion treatment includes:

[0064] (21) dispersing the support in the aqueous solution of the noble metal precursor to obtain a suspension;

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

[0066] It should be noted that, in the present 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 comprises: filtering the stirred suspension, washing the precipitate with deionized water until the pH value is 6.5-7.5, and then drying to obtain the solid material.

[0068] According to a preferred embodiment, in step (3), the calcination operation comprises: 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, and the content of hydrogen in the reducing atmosphere is 8-15 vol%.

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

[0072] Preferably, in step (4), the reduction conditions at least meet the following conditions: temperature of 300-500° C. and time of 1-3 h.

[0073] Preferably, in the method described in the present invention, the conditions are controlled so that in the obtained sulfur-resistant precious metal-based carbon monoxide oxidation catalyst, based on the total weight of the sulfur-resistant precious metal-based carbon monoxide oxidation catalyst, the content of Mg in terms of oxide is 10-45% by weight, the content of Al in terms of oxide is 25-65% by weight, the content of M in terms of oxide is 25-45% by weight, and the content of the active component in terms of metal element is 0.3-1.0% by weight.

[0074] As mentioned above, 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.

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

[0076] Preferably, the reaction raw gas used in the carbon monoxide oxidation reaction contains sulfides below 50 ppm.

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

[0078] In the present invention, unless otherwise specified, the normal temperature or room temperature involved in the following examples is 25±5°C.

[0079] The experimental methods in the following examples, unless otherwise specified, are conventional methods in the art.

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

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

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

[0083] Example 1

[0084] This example is used to illustrate 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 is prepared by a co-precipitation method using urea as a 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. 2+ 、Al 3+ 、M x+ The total concentration of the three types of metal cations is 0.14 mol / L, the concentration of urea is 2.0 mol / L, and then the mixed solution is placed in a 96°C water bath and vigorously stirred at a speed of 300 r / min for 24 hours to obtain a hydrotalcite dispersion. After filtering, the filter residue is washed with deionized water until the pH value of the eluate is 7, and the M-Mg-Al ternary hydrotalcite is obtained after drying, wherein M is Fe;

[0087] SS2, placing the M-Mg-Al ternary hydrotalcite in the center of a quartz boat, and then placing the quartz boat in the center of a quartz tube heating section of a tubular furnace, heating the temperature from room temperature to 300° C. at a heating rate of 1° C. / min in the presence of Ar, calcining at a constant temperature for 3 h, and sealing and storing after cooling to obtain the carrier;

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

[0089] SS4, heating the solid material to 500° C. at a heating rate of 1° C. / min, calcining in air for 4 h, and crushing to obtain a powder intermediate with a volume average particle size of 75 μm;

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

[0091] ICP-OES characterization revealed that in the catalyst P1, based on the total weight, the content of Mg in terms of oxide was 13.7 wt %, the content of Al in terms of oxide was 54.2 wt %, the content of Fe in terms of oxide was 31.4 wt %, and the content of Pd in ​​terms of metal element was 0.5 wt %.

[0092] Figure 2 The SEM image of P1 is shown. Figure 2 It can be seen that catalyst P1 exhibits an obvious lamellar structure, indicating that catalyst P1 retains the lamellar basic structure of hydrotalcite during the synthesis process. Figure 3 The TEM image of P1 is shown. Figure 3 It can be seen that relatively uniform alloy particles with a volume average particle size of 7 nm are formed on catalyst P1.

[0093] Example 2

[0094] This embodiment is carried out in a similar manner to that of embodiment 1, except that the types and amounts of some substances in step SS1 are different. 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. 2+ 、Al 3+ 、M x+ The total concentration of the three types of metal cations is 0.13 mol / L, the concentration of urea is 2.0 mol / L, and the mixed solution is then placed in a 96°C water bath and vigorously stirred at a speed of 400 r / min for 24 hours to obtain a hydrotalcite dispersion. After filtering, the filter residue is washed with deionized water until the pH value of the eluate is 7. After drying, the M-Mg-Al ternary hydrotalcite is obtained, wherein M is Ni.

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

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

[0098] Finally, the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst was obtained and named P2.

[0099] According to ICP-OES characterization, in the catalyst P2, based on the total weight, the content of Mg in terms of oxide is 13.2 wt%, the content of Al in terms of oxide is 50.7 wt%, the content of Ni in terms of oxide is 30.0 wt%, and the content of Pd in ​​terms of metal element is 0.7 wt%;

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

[0101] Example 3

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

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

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

[0105] S3. At a rotation speed of 300 r / min, solution A and solution B were added into a three-necked flask placed in a 65° C. water bath using a separatory funnel and mixed for 24 h to obtain a precipitate. During the mixing process, the pH value of the mixed solution was controlled to be maintained at 10.5 by dropping a 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] 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 parameter conditions are changed. The specific operations include:

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

[0109] Finally, the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst is obtained, which is named P3;

[0110] According to ICP-OES characterization, in the catalyst P3, based on the total weight, the content of Mg in terms of oxide is 14.4 wt%, the content of Al in terms of oxide is 52.3 wt%, the content of Co in terms of oxide is 32.4 wt%, and the content of Au in terms of metal element is 0.5 wt%;

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

[0112] Comparative Example 1

[0113] This comparative example is carried out by a method similar to that of Example 1, except that in step SS3, Pd is directly loaded by 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 measuring cylinder, and after being knocked on a flat surface, the dense volume was read as 0.8 mL (V1); 2 mL (V2) of water was added, and after being fully stirred and allowed to stand for 12 h, the volume of the mixed solution was read as 2.0 mL (V3); the saturated water absorption rate (ω) of the FeMgAl carrier was calculated to be 0.8 mL / g by the following formula:

[0115]

[0116] Immersion in equal volume: 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 by the following formula: t For 8mL:

[0117] V t =m 2* ω(mL)

[0118] m2: mass of the support to be impregnated, g;

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

[0120] ICP-OES characterization revealed that in the catalyst DP1, based on the total weight, the content of Mg in terms of oxide was 14.3 wt %, the content of Al in terms of oxide was 54.7 wt %, the content of Fe in terms of oxide was 28.3 wt %, and the content of Pd in ​​terms of metal element was 2.5 wt %.

[0121] Comparative Example 2

[0122] This comparative example was carried out in a similar manner to Example 1, except that the carrier was prepared by the following method:

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

[0124] Subsequently, magnesium nitrate and ferric nitrate were used as precursors to prepare 6 mL of precursor solution (wherein the magnesium ion concentration was 0.06 mol / L and the iron ion concentration was 0.07 mol / L), and the magnesium element and the nickel element were loaded on 10 g of alumina by the equal volume impregnation method in Comparative Example 1. The loaded product was dried at 80 ° C for 6 h, and then heated to 500 ° C at a heating rate of 2 ° C / min and calcined for 2 h to obtain a carrier;

[0125] The carrier 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 in the catalyst DP2, based on the total weight, the content of Mg in terms of oxide was 13.2 wt %, the content of Al in terms of oxide was 50.7 wt %, the content of Fe in terms of oxide was 30.0 wt %, and the content of Pd in ​​terms of metal element was 0.69 wt %.

[0127] Comparative Example 3

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

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

[0130] Comparative Example 4

[0131] This comparative example was carried out in a similar manner to Example 1, except that the loaded 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, to obtain a noble metal-based carbon monoxide oxidation catalyst named DP4.

[0132] ICP-OES characterization revealed that in the catalyst DP4, based on the total weight, the content of Mg in terms of oxide was 13.7 wt %, the content of Al in terms of oxide was 54.2 wt %, the content of Fe in terms of oxide was 31.4 wt %, and the content of Ag in terms of metal element was 0.5 wt %.

[0133] Comparative Example 5

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

[0135] ICP-OES characterization revealed that in the catalyst DP5, based on the total weight, the content of Mg in terms of oxide was 13.7 wt %, the content of Al in terms of oxide was 54.4 wt %, the content of Fe in terms of oxide was 31.5 wt %, and the content of active metal Pd in ​​terms of metal element was 0.15 wt %.

[0136] Test Example 1

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

[0138] The composition of the reaction raw gas is: 0.5 vol% CO (C0), 0.005 vol% H2S, 5 vol% O2 and 94.495 vol% CO2, and the reaction space velocity is 5000h -1 .

[0139] The concentration of CO at the reactor outlet at time t was measured by gas chromatography (C t ), and calculate the CO conversion rate according to the following formula: CO conversion rate t / %=(C t- C0) / C0*100%;

[0140] Monitor the change of CO conversion rate of product P1 over time within 200h. 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 above 99%.

[0141] The CO conversion rate of the catalyst prepared in the above example after reaction at 280°C for 200 hours was calculated. The results are shown in Table 1.

[0142] Table 1

[0143]

[0144] It can be seen from the above that the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst provided by the present invention is -1 , reaction temperature of 280°C, inlet CO concentration of 5000ppm and the presence of 50ppm hydrogen sulfide, after 200h reaction time, the CO conversion rate can still be maintained above 99%, and the catalyst has a simple composition and has prospects for industrial application.

[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, characterized in that: The sulfur-resistant noble metal-based carbon monoxide oxidation catalyst contains a carrier and an active component supported on the carrier, wherein the active component is Pd and / or Au, and the carrier 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; Based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of the active component in terms of metal element is 0.3-1.2% by weight.

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, the content of Mg in terms of oxide is 10-45% by weight, the content of Al in terms of oxide is 25-65% by weight, the content of M in terms of oxide is 25-45% by weight, and the content of the active component in terms of metal element is 0.3-1.0% by weight; Preferably, the volume average particle size of the alloy particles is 4-10 nm.

3. A method for preparing a sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, characterized in that: The method comprises the following steps: (1) calcining M-Mg-Al ternary hydrotalcite to obtain a carrier, wherein M is at least one of Fe, Co, Ni, Zn, Cu and Cr; (2) impregnating the support with an aqueous solution of a noble metal precursor to obtain a solid material; (3) calcining and crushing the solid material in sequence to obtain a powder intermediate having a volume average particle size of no more than 75 μm; (4) reducing the powder intermediate to obtain the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst; The conditions are controlled so that in the obtained sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, the content of active components in terms of metal elements is 0.3-1.2% by weight based on the total weight of the sulfur-resistant noble metal-based carbon monoxide oxidation catalyst, and the active components are Pd and / or Au; The noble metal precursor is sodium tetrachloropalladate and / or chloroauric acid.

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

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

8. The method according to any one of claims 3 to 7, wherein: In step (2), the concentration of the aqueous solution of the noble metal precursor is 0.1-0.5 mol / L; Preferably, the concentration of the aqueous solution of the noble metal precursor is 0.15-0.4 mol / L.

9. The method according to any one of claims 3 to 8, wherein: In step (2), the operation of the immersion treatment includes: (21) dispersing the support in the aqueous solution of the noble metal precursor to obtain a suspension; (22) Stirring the suspension with a pH value of 5-10 at 40-90° C. for 5-48 hours and then separating to obtain the solid material.

10. The method according to any one of claims 3 to 9, wherein: 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.

11. The method according to any one of claims 3 to 10, wherein: In step (4), the reduction is carried out in a reducing atmosphere, and the content of hydrogen in the reducing atmosphere is 8-15 vol%.

12. The method according to any one of claims 3 to 11, wherein: In step (4), the reduction conditions at least meet the following requirements: temperature of 300-500° C. and time of 1-3 h.

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

14. Use 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 use according to claim 14, wherein: The reaction raw gas used in the carbon monoxide oxidation reaction contains sulfides below 50 ppm.

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