Sulfur-tolerant CO 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 CO oxidation catalyst as well as a preparation method and application thereof. The method comprises the following steps: (1) in the presence of carrier gas, contacting a platinum source with a to-be-plated base material to carry out first contact reaction to obtain a material I; (2) in the presence of carrier gas, passivating a modifier and the material I to obtain a passivated material; (3) carrying out second contact reaction on the passivation material and a second metal source to obtain a material II; and (4) carrying out a third contact reaction on a hydrazine reducing agent and the material II, and roasting a product obtained after the third contact reaction to obtain the sulfur-tolerant CO oxidation catalyst. The sulfur-tolerant CO oxidation catalyst prepared by the method provided by the invention has the advantages of high metal additive dispersity, high catalytic conversion rate, low activation temperature and excellent catalytic stability in a sulfur-containing atmosphere.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-catalytic materials, and in particular to a sulfur-resistant CO oxidation catalyst and a preparation method and application thereof. Background Art

[0002] Carbon monoxide (CO) is a colorless, odorless, toxic gas that has a strong binding force with hemoglobin. At higher concentrations, it can cause varying degrees of poisoning symptoms in people, harming the brain, heart, liver, kidneys, lungs and other tissues, and even causing electric shock-like death. The minimum lethal concentration for humans to inhale is 5000ppm. CO mainly comes from the incomplete combustion or partial oxidation of coal, gasoline and natural gas. Among them, industrial furnaces and civilian boilers, stoves, as well as internal combustion engines and automobile exhaust are the main sources of carbon monoxide pollution. With the increasingly stringent environmental protection requirements, the country has successively imposed strict restrictions on the CO concentration in the exhaust gas of chemical production equipment. Some regions have issued relevant standards to clarify that the maximum allowable emission of CO is 200mg / m 3 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, when the CO concentration in industrial waste gas is >5vol%, the direct discharge of waste gas is not only a waste of resources, but also causes serious environmental pollution. Therefore, deep cold separation, solvent recovery or solid adsorption separation are usually used to purify, separate and purify CO. The CO content in the purified gas is very low and can be directly discharged in compliance with the standards. When the CO concentration in the tail gas is low (<20000ppm) (such as the analytical gas of the low-temperature methanol washing device used in the removal of acidic gas in the coal gasification unit), the recovery cost for this type of tail gas is relatively high. In order to meet the emission requirements, adsorption, photocatalysis, low-temperature plasma conversion, combustion and other methods are usually used to remove CO in it to meet the emission requirements. The catalytic oxidation method is based on the combustion method to introduce a high-efficiency catalyst to remove CO in it, which can reduce the temperature of the combustion process, has the advantages of simple process and high removal efficiency, and therefore has received widespread attention.

[0004] In terms of the research and development of high-efficiency catalysts, domestic and foreign scholars have begun research in the 1970s and have formed patents. Currently, there are three main types of catalysts used for CO catalytic oxidation: non-precious metal oxide type, perovskite oxide type and precious metal catalyst.

[0005] Among them, the non-precious metal oxide catalyst used for low-temperature oxidation of CO is mainly Hopcalite, which is a composite oxide catalyst with CuO-MnOx as the main component. This catalyst is a carrier-free catalyst that can effectively remove CO at room temperature. The lattice oxygen on the catalyst surface directly participates in the reaction and reacts with CO molecules that are preferentially adsorbed on the catalyst surface and activated. The lattice oxygen vacancies caused by the reaction are supplemented by oxygen in the air adsorbed on the catalyst surface and becoming lattice oxygen. The advantage of this catalyst is low cost, and the disadvantage is poor moisture and sulfur resistance and easy deactivation.

[0006] Among them, the non-precious metal oxide cobalt oxide also has high low-temperature catalytic oxidation activity for CO. Usually, cobalt nitrate is used as a precursor and sodium hydroxide is used as a precipitant. However, sodium dodecyl sulfate needs to be used as a surfactant during the preparation process to obtain high low-temperature activity. Moreover, the minimum temperature of the cobalt oxide catalyst prepared by precipitation oxidation method for CO catalytic oxidation is 98°C, and hydrogen peroxide needs to be added as an oxidant during the preparation process.

[0007] There are also many reports on perovskite oxide catalysts for CO catalytic oxidation reactions. The perovskite rare earth composite oxide disclosed in CN1058357A is directly loaded on a carrier with mullite as the main phase. When the CO concentration is 1% and the space velocity is 60000h -1 Under the conditions of , when the reaction temperature is 250 ° C, the CO conversion rate reaches 99%. It can be seen that perovskite oxides generally require a higher reaction temperature for CO catalytic oxidation.

[0008] However, compared with non-precious metal catalysts, precious metal catalysts such as gold and palladium have better activity and stability, but are expensive. In recent years, people have begun to pay attention to the synergistic effect between precious metals and certain transition metals to improve catalyst performance and reduce catalyst costs. However, the active components loaded on such catalysts are unevenly distributed, resulting in low activity and unstable performance, which limits their application areas.

[0009] The Pd-Ag / CeO2-ZrO2-Y2O3 catalyst disclosed in CN105312064A has a CO removal rate of 95% at 140°C, but can only be used under low CO concentration conditions (200ppm), and the preparation conditions are complicated and there are many types of elements, which limits the application of the catalyst under industrial conditions.

[0010] The flower-ball-shaped cerium oxide-loaded gold nanoparticle catalyst disclosed in CN104857957A has a CO removal efficiency of 99% within the range of 25-60°C, but its gold loading is 1-4%, and the carrier is in the shape of a micron-level flower ball. The active component is gold nanoparticles. After the reaction, the gold nanoparticles are easy to agglomerate, resulting in a decrease in activity and a shortened service life, which also limits its application.

[0011] At present, there are many studies on the catalytic oxidation removal of CO. However, due to the influence of the previous process, the CO-containing waste gas of many chemical plants usually contains low concentrations of sulfides (<50ppm, including H2S, COS, etc.). The presence of sulfides will cause the precious metal catalyst to deactivate quickly, making the catalytic removal process unable to proceed smoothly. Therefore, the development of precious metal catalysts that can take into account low activation temperature, good sulfur resistance, and high stability has become an important development direction for catalysts. Summary of the invention

[0012] The purpose of the present invention is to overcome the problems of high activation temperature, poor stability and poor sulfur resistance of the catalyst used for CO catalytic oxidation in the prior art.

[0013] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a sulfur-resistant CO oxidation catalyst, the method comprising:

[0014] (1) contacting a platinum source with a base material to be plated in the presence of a carrier gas to perform a first contact reaction to obtain material I; the base material to be plated is selected from at least one of a nano-Al2O3 carrier, nano-SiO2, nano-TiO2, and a carbon nanotube, and the volume average diameter of the base material to be plated is 10 nm-30 nm;

[0015] (2) in the presence of a carrier gas, subjecting the modifier and the material I to a passivation treatment to obtain a passivated material;

[0016] (3) subjecting the passivation material to a second contact reaction with a second metal source to obtain material II; the second metal source contains at least one element selected from the group consisting of iron, nickel, cobalt and copper;

[0017] (4) subjecting the hydrazine reducing agent to a third contact reaction with the material II, and calcining the product obtained after the third contact reaction to obtain a sulfur-resistant CO oxidation catalyst;

[0018] The reaction conditions are controlled so that in the sulfur-resistant CO oxidation catalyst, the content of the platinum element is 0.1-0.5 wt% by weight and the content of the second metal element is 1.5-3.5 wt% by weight.

[0019] The second aspect of the present invention provides a sulfur-resistant CO oxidation catalyst prepared by the method described in the first aspect.

[0020] The third aspect of the present invention provides the use of the sulfur-resistant CO oxidation catalyst described in the second aspect in removing carbon monoxide from exhaust gas.

[0021] The sulfur-resistant CO oxidation catalyst provided by the present invention exhibits excellent catalytic activity in the carbon monoxide oxidation reaction, has a low activation temperature, and can also exhibit excellent catalytic stability in a sulfur-containing atmosphere.

[0022] The present invention realizes precise control of the catalyst at the nanoscale through atomic layer deposition technology, forms an inert deposition layer around the active metal, prevents particle agglomeration during the reaction process, and thus obtains a sulfur-resistant CO oxidation catalyst with high metal additive dispersion, low activation temperature, high stability and high catalytic conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a preferred sulfur-resistant CO oxidation catalyst a1 provided by the present invention;

[0024] Figure 2 This is a curve showing the change in CO conversion rate of a preferred sulfur-resistant CO oxidation catalyst a1 provided by the present invention.

[0025] Description of Reference Numerals

[0026] Deposition 1: Second contact reaction DETAILED DESCRIPTION

[0027] 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.

[0028] As mentioned above, the first aspect of the present invention provides a method for preparing a sulfur-resistant CO oxidation catalyst, the method comprising:

[0029] (1) contacting a platinum source with a base material to be plated in the presence of a carrier gas to perform a first contact reaction to obtain material I; the base material to be plated is selected from at least one of a nano-Al2O3 carrier, nano-SiO2, nano-TiO2, and a carbon nanotube, and the volume average diameter of the base material to be plated is 10 nm-30 nm;

[0030] (2) in the presence of a carrier gas, subjecting the modifier and the material I to a passivation treatment to obtain a passivated material;

[0031] (3) subjecting the passivation material to a second contact reaction with a second metal source to obtain material II; the second metal source contains at least one element selected from the group consisting of iron, nickel, cobalt and copper;

[0032] (4) subjecting the hydrazine reducing agent to a third contact reaction with the material II, and calcining the product obtained after the third contact reaction to obtain a sulfur-resistant CO oxidation catalyst;

[0033] The reaction conditions are controlled so that in the sulfur-resistant CO oxidation catalyst, the content of the platinum element is 0.1-0.5 wt% by weight and the content of the second metal element is 1.5-3.5 wt% by weight.

[0034] Preferably, the second metal source is selected from at least one of organic matter containing iron, organic matter containing nickel, organic matter containing cobalt, and organic matter containing copper.

[0035] It should be noted that, in the present invention, the weight content of the second metal element is: the total weight content of iron, nickel, cobalt and copper in the sulfur-resistant CO oxidation catalyst.

[0036] Preferably, the second metal source is selected from at least one of Fe(C5H5)2, (C5H5)2Ni, bis(N,N'-di-iso-propylacetamidine)cobalt, copper(II)bis(dimethylamino-2-propoxy), and copper acetylacetonate. The inventors found that the sulfur-resistant CO oxidation catalyst prepared under this preferred condition can eliminate ligands or change the structure of ligands, form inert adsorption sites, and prevent active metals from migrating during the reaction; directionally anchor active substances to form physical space isolation to avoid agglomeration of active species, effectively improve the dispersion of active metals, and maximize the contact interface between metals and oxides, so that the catalytic efficiency of the catalyst is higher.

[0037] Preferably, in the present invention, the amounts of the platinum element and the second metal source are controlled so that in the obtained sulfur-resistant CO oxidation catalyst, the content of the platinum element is 0.1-0.5 wt% and the content of the second metal element is 1.5-3.5 wt%.

[0038] Preferably, the volume ratio of the platinum source to the modifier is 30-50:1.

[0039] It should be noted that, in the present invention, the volume ratio of the platinum source to the modifier refers to the ratio of the total volume of the platinum source introduced in the first contact reaction to the total volume of the modifier introduced in the passivation treatment.

[0040] Preferably, in step (1), the operation of the first contact reaction comprises: using the platinum source to perform 30-50 times of coating treatment I on the base material to be plated. Preferably, in each coating treatment I, the volume flow rate of the platinum source is independently 70-180 sccm, and the introduction time of the platinum source is independently 3-20 s for every 10 g of the base material to be plated.

[0041] Preferably, the method of the present invention further comprises: in step (2), before the passivation treatment, the material I is first purged I using an inert gas, and then applied to the passivation treatment.

[0042] Preferably, in step (2), the volume flow rate of the modifier is 70-180 sccm; and the introduction time of the modifier is 3-20 s for every 10 g of the base material to be plated.

[0043] Preferably, the volume ratio of the second metal source to the hydrazine reducing agent is 120-200:1.

[0044] It should be noted that, in the present invention, the volume ratio of the second metal source to the hydrazine reducing agent refers to the ratio of the total volume of the second metal source introduced in the second contact reaction to the total volume of the hydrazine reducing agent introduced in the third contact reaction.

[0045] Preferably, in step (3), the operation of the second contact reaction includes: using the second metal source to perform 180-220 times of coating treatment II on the passivation material. The inventors have found that under this preferred condition, the second metal can be accurately deposited on the surface of the platinum source, avoiding the second metal from being loaded on the carrier or other unreasonable adsorption sites, avoiding unnecessary side reactions, and thus making the prepared sulfur-resistant CO oxidation catalyst have better catalytic sulfur resistance.

[0046] Preferably, the volume flow rate of the second metal source is independently 70-180 sccm, and the introduction time of the second metal source is independently 20-50 s for every 10 g of the base material to be plated.

[0047] Preferably, in step (4), the volume flow rate of the hydrazine reducing agent is 70-180 sccm; and the introduction time of the hydrazine reducing agent is 10-100 s for every 10 g of the base material to be plated.

[0048] Preferably, the volume flow rate of the hydrazine reducing agent is 70-130 sccm; and the introduction time of the hydrazine reducing agent is 25-55 s for every 10 g of the base material to be plated.

[0049] Preferably, in step (1), the conditions of the first contact reaction at least meet the following conditions: temperature of 150-250° C. and pressure of 80-200 Pa.

[0050] Preferably, in step (2), the conditions for the passivation treatment at least meet the following conditions: temperature of 150-250° C., pressure of 60-200 Pa, and time of 10-45 s.

[0051] Preferably, in step (3), the conditions of the second contact reaction at least meet the following conditions: temperature of 150-300° C. and pressure of 80-200 Pa.

[0052] Preferably, the method of the present invention further comprises, before carrying out the third contact reaction, post-treating the material II in an oxygen-containing atmosphere, and then carrying out the third contact reaction between the product obtained by the post-treatment and the hydrazine reducing agent.

[0053] Preferably, the oxygen-containing atmosphere is a gas with an oxygen content of 5-10 vol%.

[0054] Preferably, the post-treatment conditions at least meet the following conditions: temperature of 450-550° C., pressure of 80-200 Pa, and time of 80-200 s.

[0055] Preferably, in step (4), the conditions of the third contact reaction at least meet the following conditions: temperature of 120-350° C., pressure of 80-200 Pa, and time of 80-200 s.

[0056] Preferably, in step (4), after the material II is subjected to the third contact reaction with the hydrazine-based reducing agent, an inert gas is used to purge II to obtain the sulfur-resistant CO oxidation catalyst.

[0057] According to a preferred embodiment, the purge I and purge II conditions independently meet at least: a temperature of 30-70°C and a time of 10-200s; and

[0058] The volume flow rate of the inert gas is 10-250 sccm for every 10 g of the substrate to be plated. The inventors found that under this preferred condition, the catalytic sulfur resistance of the sulfur-resistant CO oxidation catalyst obtained is better.

[0059] More preferably, the inert gas is argon and / or helium.

[0060] Preferably, in step (2), the modifier is selected from at least one of aromatic carboxylic acid, saturated carboxylic acid, xylene and propylbenzene.

[0061] Preferably, in step (1), the platinum source is trimethyl(methylcyclopentadienyl)platinum(IV) and / or dimethyl(1,5-cyclooctadiene)platinum.

[0062] Preferably, in step (4), the structural formula of the hydrazine reducing agent is R1R2N-NR3R4, wherein R1, R2, R3 and R4 are each independently selected from hydrogen and a C1-C5 alkyl group.

[0063] Preferably, the hydrazine reducing agent is selected from at least one of methylhydrazine, ethylhydrazine, propylhydrazine, tert-butylhydrazine and anhydrous hydrazine.

[0064] According to a preferred embodiment, the method of the present invention also includes: the method is carried out in a reaction chamber connected to at least one ALD pulse valve; and in the presence of a carrier gas, the platinum source, the second metal source, the hydrazine reducing agent and / or the modifier are introduced into the reaction chamber through the pulse valve.

[0065] Preferably, the carrier gas is at least one of argon, helium and nitrogen.

[0066] Preferably, the method of the present invention further comprises: preheating the hydrazine reducing agent to 30-70° C. before performing the third contact reaction.

[0067] Preferably, the method of the present invention further comprises: preheating the platinum source and / or the second metal source to 140-180° C. before introducing them into the reaction chamber.

[0068] According to a preferred embodiment, the working temperature of the raw material transport pipeline and the ALD pulse valve in the present invention is 180-200°C, and the pressure is 10-200Pa.

[0069] According to a preferred embodiment, the method of the present invention also includes: placing the base material to be plated on a quartz plate in the reaction chamber, and after completing the purge II, calcining the obtained product in a muffle furnace under an air atmosphere of 445-455°C for 3.5-4.5h, and forming it into a sphere with an average diameter of 3-5mm by a ball rolling machine to obtain the sulfur-resistant CO oxidation catalyst.

[0070] It should be noted that the present invention has no specific requirements for the ball rolling machine, and conventional models in the art can be used, as long as the average diameter of the spheres meets the requirements of the present invention.

[0071] As mentioned above, the second aspect of the present invention provides a sulfur-resistant CO oxidation catalyst prepared by the method described in the first aspect.

[0072] As mentioned above, the third aspect of the present invention provides the use of the sulfur-resistant CO oxidation catalyst described in the second aspect in removing carbon monoxide from exhaust gas.

[0073] In the present invention, unless otherwise specified, the normal temperature or room temperature involved in the following examples is 25±3°C.

[0074] The present invention is described in detail below by way of examples. Unless otherwise specified, the raw materials used are all common commercially available products.

[0075] Base material I to be plated: nano-Al2O3 carrier with a volume average diameter of 20nm;

[0076] Base material II to be plated: nano-SiO2, with a volume average diameter of 15nm;

[0077] Base material III to be plated: nano-TiO2, with a volume average diameter of 30nm;

[0078] Base material IV to be plated: carbon nanotubes with a volume average diameter of 15 nm;

[0079] Platinum source I: trimethyl(methylcyclopentadienyl)platinum(IV), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 94442-22-5;

[0080] Platinum source II: dimethyl (1,5-cyclooctadiene) platinum, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 12266-92-1;

[0081] The second metal source I: ferrocene (Fe(C5H5)2), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 102-54-5;

[0082] The second metal source II is nickelocene ((C5H5)2Ni), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 1271-28-9;

[0083] The second metal source III: bis(N,N'-di-iso-propylacetamido)cobalt, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 635680-58-9;

[0084] The second metal source IV is nickel acetylacetonate, purchased from Shanghai MacLean Biochemical Technology Co., Ltd., CAS No. 3264-82-2;

[0085] Hydrazine reducing agent: hydrazine (anhydrous) (H4N2), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 302-01-2;

[0086] Modifier: xylene, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 1330-20-7;

[0087] Carrier gas: nitrogen;

[0088] Inert gas: Argon.

[0089] Rolling ball machine: Model ZLJ-800, disc diameter 80cm, disc edge height 120cm;

[0090] Gas chromatograph: Model GC-7890A, purchased from Agilent Technologies Shanghai Branch.

[0091] Unless otherwise specified, the operating temperature of the raw material transport pipeline and the ALD pulse valve in the following examples is 180°C and the pressure is 10Pa;

[0092] The conditions of the purge I and purge II are: temperature of 50° C. and time of 100 s.

[0093] Example 1

[0094] This example is used to illustrate a preferred method for preparing a sulfur-resistant CO oxidation catalyst provided by the present invention according to the following steps and with reference to the parameters in Table 1, specifically including:

[0095] (1) 10 g of the substrate to be plated is placed on a quartz plate in a reaction chamber, a platinum source I is preheated to 150° C., the ALD pulse valve of the platinum source is opened, the volume flow rate of the platinum source is set, and the introduction time is shown in Table 1. The platinum source is introduced into the reaction chamber with a carrier gas, and the temperature and pressure are shown in Table 1. The surface of the substrate to be plated is subjected to a coating treatment I, and the coating treatment I is repeated 40 times to complete the first contact reaction and obtain material I;

[0096] (2) using an inert gas to purge the material I, then opening the ALD pulse valve of the modifier, setting the volume flow rate and introduction time of the modifier as shown in Table 1, the temperature and pressure as shown in Table 1, introducing the modifier into the reaction chamber with a carrier gas to perform a passivation treatment with the material I, and the passivation treatment time as shown in Table 1, to obtain a passivated material;

[0097] (3) Preheating the second metal source to 150° C., opening the ALD pulse valve of the second metal source, setting the volume flow rate of the second metal source, the introduction time is shown in Table 1, introducing the second metal source into the reaction chamber with a carrier gas, the temperature and pressure are shown in Table 1, and performing coating treatment II with the surface of the passivation material, repeating coating treatment II 200 times, completing the second contact reaction, and obtaining material II;

[0098] (4) In an oxygen-containing atmosphere (oxygen content is 8 vol%) at the pressure shown in Table 1, the temperature is raised from room temperature to the temperature shown in Table 1, and material II is post-treated. The post-treatment time is shown in Table 1.

[0099] Then, at the temperature and pressure shown in Table 1, the ALD pulse valve of the hydrazine reducing agent is opened, the volume flow rate of the hydrazine reducing agent is set, and the introduction time is shown in Table 1, and the hydrazine reducing agent preheated to 70° C. is subjected to a third contact reaction with the material III, and the contact reaction time is shown in Table 1;

[0100] Then, an inert gas is used to purge II, and the purged product is scraped off the quartz plate, calcined in a muffle furnace under an air atmosphere at 450° C. for 4 hours, and formed into a sphere with an average diameter of 3.5 mm by a ball rolling machine to obtain the sulfur-resistant CO oxidation catalyst, which is named a1;

[0101] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2;

[0102] Figure 1 Schematic diagram of the structural changes during the preparation of sulfur-tolerant CO oxidation catalyst a1. Figure 1 First, active metal platinum is introduced onto the base material to be plated for coating treatment I to form material I; then a modifier is introduced for passivation treatment, i.e., a diaphragm is formed on the surface of platinum to obtain a passivated material; then a second metal element is deposited on the base material to be plated 1 (coating treatment II); finally, the diaphragm is eliminated through post-treatment to obtain a sulfur-resistant CO oxidation catalyst.

[0103] Example 2

[0104] This embodiment is carried out in a similar manner to the embodiment 1, except that: the second metal source II is used instead of the second metal source I for the second contact reaction, and the introduction time of the platinum source in each coating treatment I and the second metal source in the coating treatment II is changed. For specific parameters, see Table 1;

[0105] A sulfur-resistant CO oxidation catalyst was obtained and named a2;

[0106] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0107] Example 3

[0108] This example is carried out in a similar manner to Example 1, except that: the second metal source III is used in place of the second metal source I in the same amount and volume to carry out the second contact reaction;

[0109] A sulfur-resistant CO oxidation catalyst was obtained and named a3;

[0110] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0111] Example 4

[0112] This embodiment is carried out in a similar manner to that of embodiment 1, except that: an equal mass of base material II to be plated is used to replace base material I to be plated for the first contact reaction, the platinum source used is platinum source II, and the parameter conditions are changed. For specific parameters, see Table 1;

[0113] The sulfur-resistant CO oxidation catalyst is obtained and named as a4;

[0114] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0115] Example 5

[0116] This example is carried out in a similar manner to Example 1, except that: the base material III to be plated is used instead of the base material I to be plated for the first contact reaction to obtain the sulfur-resistant CO oxidation catalyst, named a5;

[0117] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0118] Example 6

[0119] This example is carried out in a similar manner to Example 1, except that: the base material IV to be plated is used instead of the base material I to be plated for the first contact reaction to obtain the sulfur-resistant CO oxidation catalyst, named a6;

[0120] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0121] Example 7

[0122] This example is carried out in a similar manner to Example 1, except that: a second metal source IV is used instead of the second metal source I to carry out a second contact reaction, thereby obtaining the sulfur-resistant CO oxidation catalyst, which is named a7;

[0123] The element contents in the sulfur-resistant CO oxidation catalyst are shown in Table 2.

[0124] Comparative Example 1

[0125] In this comparative example, a conventional equal volume impregnation method is used to directly load a platinum precursor (chloroplatinic acid solution) on a carrier to obtain a CO oxidation catalyst. The specific operation includes:

[0126] SS1. Weigh 0.1 g of chloroplatinic acid (H2PtCl6) and add it to a 1 L constant volume flask. Add deionized water to fully dissolve it, then make the volume to 1 L. After the solution is clarified uniformly, let it stand to obtain a chloroplatinic acid solution.

[0127] SS2, placing the nano-Al2O3 carrier in a muffle furnace, calcining at 500°C in an air atmosphere for 4 hours, with a heating rate of 3°C / min. After the calcination is completed, cooling to room temperature to obtain the treated nano-Al2O3 carrier, which is sealed and stored;

[0128] SS3, saturated water absorption rate determination: weigh 1g (M0) of the treated nano-Al2O3 carrier and add it to a 5mL measuring cylinder. After knocking it on a flat surface, read the dense volume as 1mL (V1). After adding 2mL (V2) of water, stir it thoroughly and let it stand for 12h. Read the volume of the mixed solution as 2.3mL (V3);

[0129] According to the formula: carrier saturated water absorption rate ω = ((V1+V2)-V3) / M0; (mL / g)

[0130] The calculated saturated water absorption rate of the nano-Al2O3 carrier is 0.7 mL / g.

[0131] SS4, weigh 1.52g of the chloroplatinic acid solution prepared in step (1), add it together with 1.16g of ferric nitrate (Fe(NO3)·9H2O) into a 50mL beaker, add 6.3mL of deionized water, stir and dissolve, then add 10g of the treated nano-Al2O3 carrier, stir for 0.5h at room temperature to obtain a slurry mixture. Use a sealing film to seal the beaker containing the slurry mixture. Place it in a cool and dry place and let it stand for 12h to obtain a slurry catalyst.

[0132] SS5. The slurry catalyst was placed in a crucible, and then placed in a muffle furnace in an air atmosphere, heated from room temperature to 500°C at a heating rate of 2°C / min, and calcined at 500°C for 4 hours. After calcination, it was cooled to room temperature, taken out and sealed for storage to obtain a CO oxidation catalyst, named DP1; the element content in the catalyst is shown in Table 2.

[0133] Comparative Example 2

[0134] This comparative example was carried out in a similar manner to comparative example 1, except that in step SS4, the same mass (1.16 g) of nickel nitrate was used instead of iron nitrate to obtain a CO oxidation catalyst named DP2;

[0135] The element contents in the catalyst are shown in Table 2.

[0136] Comparative Example 3

[0137] This comparative example was carried out in a similar manner to comparative example 1, except that in step SS4, the same mass (1.16 g) of cobalt nitrate was used instead of iron nitrate to obtain a CO oxidation catalyst named DP3;

[0138] The element contents in the catalyst are shown in Table 2.

[0139] Comparative Example 4

[0140] This comparative example was carried out in a similar manner to Example 1, except that: in step (1), the time for introducing the platinum source in each coating treatment I was 3 s, and a CO oxidation catalyst was obtained, named DP4;

[0141] The element contents in the catalyst are shown in Table 2.

[0142] Comparative Example 5

[0143] This comparative example is carried out in a similar manner to Example 1, except that the modifier is introduced into the reaction chamber together with the platinum source in step (1) to carry out a first contact reaction. Specifically, the operation of the first contact reaction includes:

[0144] 10 g of the base material to be plated is placed on a quartz plate in a reaction chamber, a platinum source is preheated to 150° C., the ALD pulse valve of the platinum source is opened, the volume flow rate of the platinum source is set to 80 sccm, the introduction time is 5 s, the volume flow rate of the modifier is set to 20 sccm, the introduction time is 5 s, and the platinum source and the modifier are introduced into the reaction chamber respectively with a carrier gas, and a coating treatment I is carried out on the surface of the base material to be plated at a temperature of 160° C. and a pressure of 100 Pa, and the coating treatment I is repeated 40 times to complete the first contact reaction and obtain material I;

[0145] Then, the material I is used to replace the passivation material in Example 1 to carry out the second contact reaction in step (3) with the second metal source, and finally a CO oxidation catalyst is obtained, which is named DP5;

[0146] The element contents in the catalyst are shown in Table 2.

[0147] Test Example 1

[0148] 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 250° 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, wherein:

[0149] The composition of the reaction raw gas is: 0.6 vol% CO (C0), 0.005 vol% H2S, 5 vol% O2 and 94.395 vol% CO2, and the reaction space velocity is 10000h -1 .

[0150] The concentration of CO at the reactor outlet at time t was measured by gas chromatography (C t ), and the CO conversion rate is calculated according to the following formula: CO conversion rate / % = (C0- C t ) / C0*100%;

[0151] In addition, the activation temperature T 50 That is, the temperature corresponding to when the CO conversion rate is 50%;

[0152] T 90 That is, the temperature corresponding to when the CO conversion rate is 90%;

[0153] If the CO conversion rate of the catalyst still cannot reach 50% at 250°C, the catalytic oxidation reaction temperature will continue to increase until the CO conversion rate of the catalyst reaches 50%, and this temperature will be recorded as T 50 ';

[0154] If the CO conversion rate of the catalyst still cannot reach 90% at 250°C, the catalytic oxidation reaction temperature will continue to increase until the CO conversion rate of the catalyst reaches 90%, and this temperature will be recorded as T 90 ';

[0155] Monitor the change of CO conversion rate of product a1 over time within 200h. See the results in Figure 2 ;

[0156] The CO conversion rate after 200 h of reaction was calculated for the catalyst prepared in the above example. The results are shown in Table 3.

[0157] Table 1

[0158]

[0159]

[0160] Table 2

[0161]

[0162] Table 3

[0163]

[0164] Table 3 continued

[0165]

[0166]

[0167] The reaction results show that the present invention realizes precise control of the catalyst at the nanoscale through the atomic layer deposition technology, forms an inert deposition layer around the active metal, and prevents particle agglomeration during the reaction process, thereby obtaining a sulfur-resistant CO oxidation catalyst with high metal additive dispersion, low activation temperature, high stability, and high catalytic conversion rate.

[0168] 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 method for preparing a sulfur-resistant CO oxidation catalyst, characterized in that: The method includes: (1) contacting a platinum source with a base material to be plated in the presence of a carrier gas to perform a first contact reaction to obtain material I; the base material to be plated is selected from at least one of a nano-Al2O3 carrier, nano-SiO2, nano-TiO2, and a carbon nanotube, and the volume average diameter of the base material to be plated is 10 nm-30 nm; (2) in the presence of a carrier gas, subjecting the modifier and the material I to a passivation treatment to obtain a passivated material; (3) subjecting the passivation material to a second contact reaction with a second metal source to obtain material II; the second metal source contains at least one element selected from the group consisting of iron, nickel, cobalt and copper; (4) subjecting the hydrazine reducing agent to a third contact reaction with the material II, and calcining the product obtained after the third contact reaction to obtain a sulfur-resistant CO oxidation catalyst; The reaction conditions are controlled so that in the sulfur-resistant CO oxidation catalyst, the content of the platinum element is 0.1-0.5 wt% by weight and the content of the second metal element is 1.5-3.5 wt% by weight.

2. The method according to claim 1, wherein: The second metal source is selected from at least one of Fe(C5H5)2, (C5H5)2Ni, bis(N,N'-di-iso-propylacetamidine)cobalt, copper(II)bis(dimethylamino-2-propoxy), and copper acetylacetonate.

3. The method according to claim 1 or 2, wherein: The volume ratio of the platinum source to the modifier is 30-50:

1.

4. The method according to any one of claims 1 to 3, wherein: In step (1), the operation of the first contact reaction includes: using the platinum source to perform 30-50 times of coating treatment I on the base material to be plated; Preferably, in each of the coating treatments I, the volume flow rate of the platinum source is independently 70-180 sccm, and the introduction time of the platinum source is independently 3-20 s for every 10 g of the base material to be plated.

5. The method according to any one of claims 1 to 4, wherein: In step (2), the volume flow rate of the modifier is 70-180 sccm; and the introduction time of the modifier is 3-20 s for every 10 g of the base material to be plated.

6. The method according to any one of claims 1 to 5, wherein: The volume ratio of the second metal source to the hydrazine reducing agent is 120-200:

1.

7. The method according to any one of claims 1 to 6, wherein: In step (3), the operation of the second contact reaction includes: performing 180-220 times of coating treatment II on the passivation material using the second metal source; Preferably, the volume flow rate of the second metal source is independently 70-180 sccm, and the introduction time of the second metal source is independently 20-50 s for every 10 g of the base material to be plated.

8. The method according to any one of claims 1 to 7, wherein: In step (4), the volume flow rate of the hydrazine reducing agent is 70-180 sccm; and the introduction time of the hydrazine reducing agent is 10-100 s for every 10 g of the base material to be plated; Preferably, the volume flow rate of the hydrazine reducing agent is 70-130 sccm; and the introduction time of the hydrazine reducing agent is 25-55 s for every 10 g of the base material to be plated.

9. The method according to any one of claims 1 to 8, wherein: In step (1), the conditions of the first contact reaction at least meet the following conditions: temperature of 150-250° C. and pressure of 80-200 Pa.

10. The method according to any one of claims 1 to 9, wherein: In step (2), the conditions for the passivation treatment at least meet the following requirements: temperature of 150-250° C., pressure of 60-200 Pa, and time of 10-45 s.

11. The method according to any one of claims 1 to 10, wherein: In step (3), the conditions of the second contact reaction at least meet the following conditions: temperature of 150-300° C. and pressure of 80-200 Pa.

12. The method according to any one of claims 1 to 11, further comprising, before performing the third contact reaction, post-treating the material II in an oxygen-containing atmosphere, and then performing the third contact reaction between the product obtained by the post-treatment and the hydrazine reducing agent.

13. The method according to claim 12, wherein: The post-treatment conditions at least meet the following requirements: temperature of 450-550° C., pressure of 80-200 Pa, and time of 80-200 s.

14. The method according to any one of claims 1 to 13, wherein: In step (4), the conditions of the third contact reaction at least meet the following requirements: temperature of 120-350° C., pressure of 80-200 Pa, and time of 80-200 s.

15. The method according to any one of claims 1 to 14, wherein: In step (2), the modifier is selected from at least one of aromatic carboxylic acid, saturated carboxylic acid, xylene and propylbenzene; Preferably, in step (1), the platinum source is trimethyl(methylcyclopentadienyl)platinum(IV) and / or dimethyl(1,5-cyclooctadiene)platinum.

16. The method according to any one of claims 1 to 15, wherein: In step (4), the structural formula of the hydrazine reducing agent is R1R2N-NR3R4, wherein R1, R2, R3 and R4 are each independently selected from hydrogen and a C1-C5 alkyl group; Preferably, the hydrazine reducing agent is selected from at least one of methylhydrazine, ethylhydrazine, propylhydrazine, tert-butylhydrazine and anhydrous hydrazine.

17. A sulfur-resistant CO oxidation catalyst prepared by the method according to any one of claims 1 to 16.

18. Use of the sulfur-resistant CO oxidation catalyst as claimed in claim 17 in removing carbon monoxide from exhaust gas.

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