阅读说明：本技术 一种高分散的co氧化催化剂及其制备方法和用途 (High-dispersion CO oxidation catalyst and preparation method and application thereof ) 是由 杨本涛 何凯琳 魏进超 叶恒棣 康建刚 杨峰 李俊杰 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种高分散的CO氧化催化剂及其制备方法和用途,通过“两级紫外诱导-原位CO还原预处理-变径催化反应器”的机制,使得该催化剂分散性高,含有大量小颗粒的Pt～(0)和少量PtO、PtCl-(4),其低温催化活性优异。可同时实现对Pt的价态与粒径的调节,将单原子的Pt～(0)转化为稳定、不易被再氧化的、尺寸均一的Pt～(0)催化剂,能够抑制催化剂中毒反应的发生以及防止烟气中粉尘对催化剂造成的冲刷影响,可快速带走催化剂床层放出的热量,防止高温累积,大大提高了对含低浓度CO废气的催化氧化效果。(The invention discloses a high-dispersion CO oxidation catalyst, a preparation method and application thereof, wherein the catalyst has high dispersion and contains a large number of small particles through a mechanism of' two-stage ultraviolet induction-in-situ CO reduction pretreatment-variable-diameter catalytic reactorGranular Pt 0 And small amounts of PtO and PtCl 4 Its low-temperature catalytic activity is excellent. Can simultaneously realize the adjustment of the valence state and the particle size of Pt and the single-atom Pt 0 Conversion to stable, non-reoxidizable, uniform size Pt 0 The catalyst can inhibit the occurrence of catalyst poisoning reaction and prevent the washing influence of dust in flue gas on the catalyst, can quickly take away heat emitted by a catalyst bed layer, prevent high-temperature accumulation and greatly improve the catalytic oxidation effect on waste gas containing low-concentration CO.)

1. a highly dispersed CO oxidation catalyst characterized by: the catalyst is prepared by the following method: firstly, putting a catalyst substrate coated with a carrier layer into an auxiliary agent for impregnation, and carrying out heat treatment after the impregnation is finished; then putting the catalyst substrate into the active component for dipping under the condition of ultraviolet irradiation, and carrying out heat treatment again after dipping; and finally, carrying out light treatment on the catalyst substrate by adopting ultraviolet light to obtain the high-dispersion CO oxidation catalyst.

2. The catalyst of claim 1, wherein: the substrate is made of high-temperature-resistant mineral materials; preferably one of cordierite, gamma-alumina and mullite; and/or

The carrier is titanium dioxide; preferably, the content of anatase titanium dioxide in the titanium dioxide is 75-100%, preferably 80-100%; the mesoporous aperture is 5-40 nm, preferably 10-20 nm; the surface area is 50-200m²Per g, preferably from 60 to 100m²(ii)/g; the average particle size is 2-10 μm, preferably 5-8 μm; and/or

The active component is platinum tetrachloride; and/or

The auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt; preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

3. The catalyst according to claim 1 or 2, characterized in that: the ratio of the content of the carrier to the volume of the matrix is 100-300g/L, preferably 150-200g/L, and more preferably 170-190 g/L; and/or

The content of the auxiliary agent is 0-10 wt%, preferably 0.1-7 wt%, and more preferably 0.1-3 wt% of the mass of the carrier; and/or

The content of the active component is 0.05-1 wt%, preferably 0.08-0.5 wt%, and more preferably 0.1-0.3 wt% of the mass of the carrier.

4. The catalyst of any one of claims 1-3, wherein: the heat treatment is drying and then roasting treatment; and/or

The wavelength of the ultraviolet light is 280-400 nm, and preferably 300-400 nm.

5. A method of preparing a highly dispersed CO oxidation catalyst or a highly dispersed CO oxidation catalyst according to any one of claims 1 to 4, wherein: the method comprises the following steps:

1) coating the carrier on the surface of the substrate, and then carrying out heat treatment to obtain a catalyst substrate with a carrier layer;

2) putting the catalyst substrate with the carrier layer into a solution containing an auxiliary agent for impregnation, and then carrying out heat treatment to obtain the catalyst substrate with the carrier layer loaded with the auxiliary agent;

3) under the condition of ultraviolet irradiation, the catalyst substrate with the loading assistant carrier layer is put into a solution containing active components for dipping, then heat treatment is carried out, and finally light treatment is carried out through ultraviolet light, so that the high-dispersion CO oxidation catalyst is obtained.

6. The method of claim 5, wherein: the substrate is made of high-temperature-resistant mineral materials; preferably one of cordierite, gamma-alumina and mullite; and/or

The carrier is titanium dioxide; preferably, the content of anatase in the titanium dioxide is 75-100%, preferably 80-100%; the mesoporous aperture is 5-40 nm, preferably 10-20 nm; the surface area is 50-200m²Per g, preferably from 60 to 100m²(ii)/g; the average particle size is 2-10 μm, preferably 5-8 μm; and/or

The active component is platinum tetrachloride; and/or

The auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt; preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

7. The method according to claim 5 or 6, characterized in that: in step (b)In the step 1), coating the carrier on the surface of the substrate specifically comprises the following steps: adding TiO into the mixture₂Mixing the powder, the silica sol and water to prepare slurry, and then pouring the slurry on a matrix and curing; the thickness of the washcoat after washcoat was about 50-500 μm.

8. The method according to any one of claims 5-7, wherein: the heat treatment is drying treatment and then roasting treatment; wherein the drying temperature is 60-150 ℃, the preferred drying temperature is 80-120 ℃, and the drying time is 0.2-8 h, the preferred drying time is 0.5-5 h; and/or

The roasting temperature is 300-800 ℃, and preferably 400-600 ℃; the roasting time is 0.3-10 h, preferably 0.5-8 h.

9. The method according to any one of claims 5-8, wherein: in the step 3), the wavelength of the ultraviolet light is 280-400 nm, preferably 300-400 nm;

wherein the time of the first ultraviolet irradiation is 0.3-5 h, preferably 0.5-3 h; the temperature is 20-120 ℃, and preferably 25-100 ℃; and/or

The time of the second ultraviolet light treatment is 0.3-5 h, preferably 0.5-3 h; the temperature is 20 to 120 ℃, preferably 25 to 100 ℃.

10. Use of a highly dispersed CO oxidation catalyst according to any one of claims 1 to 4 or a highly dispersed CO oxidation catalyst prepared by a process according to any one of claims 5 to 9, wherein: the high-dispersion CO oxidation catalyst is used for treating waste gas containing low-concentration CO, preferably sintering flue gas, tail gas of a rotary kiln for extracting iron and reducing zinc, and soot tail gas of a steel rolling heating furnace.

11. Use of a highly dispersed CO oxidation catalyst according to claim 10, characterized in that: in the low concentration CO-containing exhaust gas: the concentration of CO is 4000-20000 mg/m³Preferably 4500-18000 mg/m³More preferably 5000 to 15000mg/m³(ii) a And/or

In the low concentration CO-containing exhaust gas: SO (SO)₂The concentration of (A) is 0 to 1000mg/m³Preferably 30 to 800mg/m³More preferably 50 to 500mg/m³(ii) a And/or

In the low concentration CO-containing exhaust gas: h₂The concentration of O is 1-30 wt%, preferably 3-25 wt%, more preferably 5-20 wt%; and/or

The temperature of the low-concentration CO-containing waste gas is 100-220 ℃, preferably 110-200 ℃, and more preferably 120-170 ℃.

12. Use of a highly dispersed CO oxidation catalyst according to claim 10 or 11, characterized in that: the method for treating the waste gas containing low-concentration CO by using the high-dispersion CO oxidation catalyst comprises the following steps:

s1) closing an air inlet valve of the waste gas containing low-concentration CO, opening a reducing gas inlet valve, and activating the high-dispersion CO oxidation catalyst by using the reducing gas to obtain the activated high-dispersion CO oxidation catalyst;

s2) closing the reducing gas inlet valve, opening the inlet valve of the waste gas containing low-concentration CO, and treating the waste gas containing low-concentration CO by using the activated high-dispersion CO oxidation catalyst to obtain purified gas.

13. Use according to claim 12, characterized in that: the reducing gas is a mixed gas containing water vapor and CO; the temperature of the reducing gas is 150-320 ℃, and preferably 170-300 ℃; the activation treatment time is 1-5 h, preferably 1.5-4 h;

preferably, the concentration of CO in the reducing gas is 0.3-5 wt%, preferably 0.5-3 wt%; the concentration of the water vapor in the reducing gas is 0-10 wt%, preferably 3-8 wt%.

14. Use according to claim 13, characterized in that: the reducing gas is prepared by the following method: atomizing water by compressed gas to obtain water vapor; meanwhile, part of the coal gas is mixed with air to be combusted to obtain hot air; finally, mixing part of the coal gas, hot air and water vapor to obtain the reducing gas;

preferably, the coal gas is blast furnace gas and/or coke oven gas; the compressed gas is compressed nitrogen.

15. Use according to any one of claims 10 to 14, characterized in that: the treatment of the high-dispersion CO oxidation catalyst for the waste gas containing low-concentration CO is carried out by a waste gas treatment system based on a reducing catalytic reactor, wherein the system comprises a waste gas inlet pipeline (L1), a reducing gas preparation unit (1), a reducing catalytic reactor (2) and a purified gas discharge pipeline (L2); the exhaust gas inlet pipeline (L1) is communicated with an air inlet of the exhaust gas catalytic device (2), and an exhaust port of the variable diameter catalytic reactor (2) is communicated with a purified gas discharge pipeline (L2); in the variable-diameter catalytic reactor (2), a plurality of catalyst bed layers (201) are arranged according to the trend of the airflow, and the effective bed layer areas of the plurality of catalyst bed layers (201) are gradually decreased layer by layer along the trend of the airflow;

preferably, the reducing gas preparation unit (1) comprises an atomizer (101), a gas mixing chamber (102) and a hot air device (103); the exhaust port of the atomizer (101) is communicated with the air inlet of the air mixing chamber (102) through a third pipeline (L3); the exhaust port of the gas mixing chamber (102) is communicated with an exhaust gas inlet pipeline (L1) through a fourth pipeline (L4); and the exhaust port of the hot air device (103) is communicated with an exhaust gas inlet pipeline (L1) through a fifth pipeline (L5).

16. Use according to claim 15, characterized in that: the effective bed layer areas of the plurality of catalyst bed layers (201) decrease gradually layer by layer along the airflow direction, and specifically comprises the following steps: the variable-diameter catalytic reactor (2) is of a cylindrical structure, the sizes of a plurality of catalyst bed layers (201) are consistent, and blind plates (202) are arranged in the plurality of catalyst bed layers (201); according to the trend of the airflow, the areas of the blind plates (202) in the plurality of catalyst bed layers (201) are gradually increased layer by layer, and the increasing mode of the areas of the blind plates (202) is that the areas are gradually increased layer by layer from the edges of the plurality of catalyst bed layers (201) to the central point direction thereof; or

The effective bed layer areas of the plurality of catalyst bed layers (201) decrease gradually layer by layer along the airflow direction, and specifically comprises the following steps: according to the trend of the airflow, the reducing catalytic reactor (2) is of a horn-shaped structure with gradually decreasing inner diameter, and the areas of a plurality of catalyst bed layers (201) are gradually decreased layer by layer;

preferably, the number of catalyst beds (201) is from 1 to 10, preferably from 2 to 8, more preferably from 3 to 5.

17. Use according to claim 15 or 16, characterized in that: the atomizer (101) is also provided with a water inlet pipeline (104) and a compressed gas inlet pipeline (105); and/or

The gas mixing chamber (102) is also provided with a first gas conveying pipeline (106); and/or

A second gas conveying pipeline (107) is further arranged on the hot air device (103), and preferably, a combustion-supporting air pipeline (108) is arranged on the second gas conveying pipeline (107); and/or

An activated gas discharge pipeline (L6) is further arranged on the purified gas discharge pipeline (L2).

18. Use according to claim 17, characterized in that: the system also comprises a GGH heat exchanger (3); the GGH heat exchanger (3) is arranged on an exhaust gas inlet pipeline (L1) and a purified gas discharge pipeline (L2) at the same time; wherein, on the exhaust gas inlet pipeline (L1), the GGH heat exchanger (3) is positioned between the fourth pipeline (L4) and the fifth pipeline (L5); on the purified gas discharge pipeline (L2), the GGH heat exchanger (3) is positioned between the reducing catalytic reactor (2) and the activated gas discharge pipeline (L6).

Technical Field

The invention relates to a CO oxidation catalyst technology, in particular to a high-dispersion CO oxidation catalyst, a preparation method and application thereof, belonging to the technical field of CO oxidation catalysis.

Background

Steel smelting produces large quantities of CO-containing gas due to either inadequate combustion of the fuel or the need for reactive characteristics of the process itself. Among them, gases containing high concentration of CO, such as blast furnace gas and coke oven gas, have been effectively utilized because of their high calorific value. However, a lot of waste gases containing low-concentration CO exist in steel smelting, such as sintering flue gas, tail gas of a rotary kiln for extracting iron and reducing zinc, and soot tail gas of a steel rolling heating furnace, and the like, and are not effectively utilized and treated. The current treatment technology aims at the treatment technology of low-concentration CO waste gas. Mainly including direct combustion, solid adsorption, liquid absorption, catalytic oxidation, etc. The catalytic oxidation method has the advantages of short flow and full utilization of latent heat energy, and meets the requirements of CO treatment and resource utilization.

Considering that the CO flue gas in the steel industry generally contains sulfur and water, particularly sulfur, most of the catalyst poisoning is caused. The combined investigation found that Pt is most difficult to react with SO₂The reaction takes place. Thus, Pt-supported noble metal catalystRelatively more applicable. However, when the Pt-loaded catalyst is applied to industrial flue gas treatment, the problems of poor low-temperature activity and low CO conversion rate (low utilization rate) of unit Pt are also faced. The large-scale application is greatly limited.

Aiming at the problems of poor low-temperature activity and low CO conversion rate of unit Pt, the current domestic and foreign researches mainly focus on realizing the low-temperature activity and the low CO conversion rate by improving the content of 0-valence Pt. Such as additional surfactant, multi-metal doping, ultraviolet irradiation, reducing gas treatment, etc. The ultraviolet irradiation has the advantages of clean reaction, high speed and no introduction of other impurities, and is widely used at present. For example, in the chinese patent CN 109569686 a, after the noble metal solution and the activated carbon slurry are mixed uniformly, ultraviolet irradiation is adopted, the wavelength of ultraviolet light is controlled at 315-. Chinese patent CN 104084193A, prepared from carbon carrier and H by ultraviolet irradiation₂PtCl₆Or (NH)₄)₂PtCl₆Mixing the titanium precursor, the regulator and ethanol to obtain a mixed suspension, irradiating for 20-30 h under 315-400 nm ultraviolet light to change high valence platinum into 0 valence, and controlling to obtain Pt catalysts with different Pt reduction degrees and shapes. Chinese patent CN 111139108A, reports the use of ultraviolet irradiation H₂PtCl₆The solution realizes reduction loading of Pt, and simultaneously reduces Pt by combining with hydrogen so as to improve the content of Pt in a 0 valence state. Thereby improving the carbon monoxide low-temperature catalytic activity of the catalyst.

Through research, the activity of the Pt-loaded catalyst is improved, the content of Pt in a 0 valence state is only improved, and the reaction efficiency can also be improved by improving the dispersity of Pt. At present, the utilization of Pt is focused on a microscopic layer, and no applicable reactor is available, so that the utilization rate of Pt is low, and the use cost is increased.

Disclosure of Invention

Aiming at the defects of the prior art, the invention greatly improves the catalytic oxidation effect of the waste gas containing low-concentration CO by establishing a mechanism of 'two-stage ultraviolet induction-in-situ CO reduction pretreatment-variable-diameter catalytic reactor'. Wherein the preparation is realized by adopting a two-stage ultraviolet induction modeA highly dispersed CO oxidation catalyst. The catalyst has high dispersibility, and contains a large amount of Pt0 with small particles and small amounts of PtO and PtCl₄And the low-temperature catalytic activity is excellent. Adopts 'in-situ CO reduction pretreatment' to simultaneously adjust the valence state and the particle size of Pt, and the single-atom Pt⁰Conversion to stable, non-reoxidizable, uniform size (around 2 nm) Pt⁰Catalyst (low coordination number). Further, the utilization efficiency of the catalyst is improved through the variable-diameter catalytic reactor, the occurrence of catalyst poisoning reaction is inhibited, the washing influence of dust in flue gas on the catalyst is prevented, the heat emitted by a catalyst bed layer can be quickly taken away, and high-temperature accumulation is prevented.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

according to a first embodiment of the present invention, a highly dispersed CO oxidation catalyst is provided.

A highly dispersed CO oxidation catalyst, the catalyst being prepared by: the catalyst substrate coated with the support layer is first impregnated in an auxiliary agent, and the impregnation is completed and heat treated. Then the catalyst substrate is put into the active component for impregnation under the condition of ultraviolet irradiation, and heat treatment is carried out again after the impregnation is finished. And finally, carrying out light treatment on the catalyst substrate by adopting ultraviolet light to obtain the high-dispersion CO oxidation catalyst.

Preferably, the matrix is a high temperature resistant mineral material. Preferably one of cordierite, gamma-alumina, and mullite.

Preferably, the support is titanium dioxide. Preferably, the content of anatase titania in the titania is 75 to 100%, preferably 80 to 100%. The mesoporous aperture is 5-40 nm, preferably 10-20 nm. The surface area is 50-200m²Per g, preferably from 60 to 100m²(ii) in terms of/g. The average particle size is 2 to 10 μm, preferably 5 to 8 μm.

Preferably, the active component is platinum tetrachloride.

Preferably, the auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt. Preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

Preferably, the ratio of the content of the carrier to the volume of the matrix is 100-300g/L, preferably 150-200g/L, and more preferably 170-190 g/L.

Preferably, the adjuvant is present in an amount of 0 to 10 wt%, preferably 0.1 to 7 wt%, more preferably 0.1 to 3 wt% of the mass of the carrier.

Preferably, the active ingredient is present in an amount of 0.05 to 1 wt%, preferably 0.08 to 0.5 wt%, more preferably 0.1 to 0.3 wt% of the mass of the carrier.

Preferably, the heat treatment is a drying and then baking treatment.

Preferably, the wavelength of the ultraviolet light is 280-400 nm, preferably 300-400 nm.

According to a second embodiment of the present invention, a method for preparing a highly dispersed CO oxidation catalyst is provided.

A method of preparing a highly dispersed CO oxidation catalyst or a method of preparing a highly dispersed CO oxidation catalyst according to the first embodiment, the method comprising the steps of:

1) the carrier is coated on the surface of the substrate and then heat-treated to obtain the catalyst substrate with the carrier layer.

2) The catalyst substrate having the support layer is immersed in a solution containing an assistant and then subjected to heat treatment to obtain a catalyst substrate having a support layer supporting an assistant.

3) Under the condition of ultraviolet irradiation, the catalyst substrate with the loading assistant carrier layer is put into a solution containing active components for dipping, then heat treatment is carried out, and finally light treatment is carried out through ultraviolet light, so that the high-dispersion CO oxidation catalyst is obtained.

Preferably, the matrix is a high temperature resistant mineral material. Preferably one of cordierite, gamma-alumina, and mullite.

Preferably, the support is titanium dioxide. Preferably, the titanium dioxide has an anatase content of 75 to 100%, preferably 80 to 100%. The mesoporous aperture is 5-40 nm, preferably 10-20 nm. Surface area thereofIs 50-200m²Per g, preferably from 60 to 100m²(ii) in terms of/g. The average particle size is 2 to 10 μm, preferably 5 to 8 μm.

Preferably, the active component is platinum tetrachloride.

Preferably, the auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt. Preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

Preferably, in step 1), the coating of the carrier on the surface of the substrate is specifically: adding TiO into the mixture₂The powder, silica sol, and water are mixed to prepare a slurry, which is then poured onto the substrate and cured (e.g., dried, baked, roasted, etc.). The thickness of the washcoat after washcoat was about 50-500 μm.

Preferably, the heat treatment is a drying treatment and then a baking treatment. Wherein the drying temperature is 60-150 ℃, preferably 80-120 ℃, and the drying time is 0.2-8 h, preferably 0.5-5 h.

Preferably, the roasting temperature is 300-800 ℃, and preferably 400-600 ℃. The roasting time is 0.3-10 h, preferably 0.5-8 h.

Preferably, in the step 3), the wavelength of the ultraviolet light is 280 to 400nm, and preferably 300 to 400 nm.

Wherein, the time of the first ultraviolet irradiation is 0.3 to 5 hours, preferably 0.5 to 3 hours. The temperature is 20 to 120 ℃, preferably 25 to 100 ℃.

The time of the second ultraviolet light treatment is 0.3-5 h, preferably 0.5-3 h. The temperature is 20 to 120 ℃, preferably 25 to 100 ℃.

According to a third embodiment of the present invention, there is provided the use of a highly dispersed CO oxidation catalyst.

Use of a highly dispersed CO oxidation catalyst for the treatment of low CO-containing exhaust gas, preferably for the treatment of sintering flue gas, iron and zinc extracting rotary kiln exhaust gas, steel rolling furnace soot exhaust gas, etc., or use of a highly dispersed CO oxidation catalyst as described in the first embodiment or a highly dispersed CO oxidation catalyst prepared by the method of the second embodiment.

Preferably, in the low concentration CO-containing exhaust gas: the concentration of CO is 4000-20000 mg/m³Preferably 4500-18000 mg/m³More preferably 5000 to 15000mg/m³。

Preferably, SO₂The concentration of (A) is 0 to 1000mg/m³Preferably 30 to 800mg/m³More preferably 50 to 500mg/m³。

Preferably, H₂The concentration of O is 1 to 30 wt%, preferably 3 to 25 wt%, and more preferably 5 to 20 wt%.

Preferably, the temperature of the waste gas is 100-220 ℃, preferably 110-200 ℃, and more preferably 120-170 ℃.

Preferably, the treatment of the waste gas containing low concentration of CO by using the high-dispersion CO oxidation catalyst is as follows:

s1) closing an air inlet valve of the waste gas containing low-concentration CO, opening a reducing gas inlet valve, and activating the high-dispersion CO oxidation catalyst by using the reducing gas to obtain the activated high-dispersion CO oxidation catalyst.

S2) closing the reducing gas inlet valve, opening the inlet valve of the waste gas containing low-concentration CO, and treating the waste gas containing low-concentration CO by using the activated high-dispersion CO oxidation catalyst to obtain purified gas.

Preferably, the reducing gas is a mixed gas containing water vapor and CO. The temperature of the reducing gas is 150-320 ℃, and preferably 170-300 ℃. The activation treatment time is 1 to 5 hours, preferably 1.5 to 4 hours.

Preferably, the concentration of CO in the reducing gas is 0.3 to 5 wt%, preferably 0.5 to 3 wt%. The concentration of the water vapor in the reducing gas is 0-10 wt%, preferably 3-8 wt%.

The content of oxygen in the reducing gas is extremely low, and the content of oxygen is preferably 0.

Preferably, the reducing gas is prepared by the following method: atomizing water by compressed gas to obtain water vapor. Meanwhile, part of the coal gas is mixed with air to be combusted to obtain hot air. And finally, mixing part of the coal gas, hot air and water vapor to obtain the reducing gas.

Preferably, the gas is blast furnace gas and/or coke oven gas. The compressed gas is compressed nitrogen.

Preferably, the treatment of the high-dispersion CO oxidation catalyst for the low-concentration CO-containing exhaust gas is performed by an exhaust gas treatment system based on a variable-diameter catalytic reactor, and the system comprises an exhaust gas inlet pipeline, a reducing gas preparation unit, a variable-diameter catalytic reactor and a purified gas discharge pipeline. The waste gas inlet pipeline is communicated with the gas inlet of the waste gas catalytic device, and the exhaust port of the variable diameter catalytic reactor is communicated with the purified gas discharge pipeline. In the reducing catalytic reactor, a plurality of catalyst bed layers are arranged according to the trend of the airflow, and the effective bed layer areas of the plurality of catalyst bed layers are gradually decreased layer by layer along the trend of the airflow.

Preferably, the reducing gas preparation unit comprises an atomizer, a gas mixing chamber and a hot air device. And the exhaust port of the atomizer is communicated with the air inlet of the air mixing chamber through a third pipeline. And the exhaust port of the gas mixing chamber is communicated with the waste gas inlet pipeline through a fourth pipeline. And an exhaust port of the hot air device is communicated with the waste gas inlet pipeline through a fifth pipeline.

Preferably, the step-by-step gradual decrease of the effective bed areas of the plurality of catalyst beds along the airflow direction is as follows: the reducing catalytic reactor is of a cylindrical structure, the sizes of a plurality of catalyst bed layers are consistent, and blind plates are arranged in the plurality of catalyst bed layers. According to the trend of the air flow, the areas of the blind plates in the plurality of catalyst bed layers are gradually increased layer by layer, and the increasing mode of the areas of the blind plates is that the areas of the blind plates are gradually increased layer by layer from the edges of the plurality of catalyst bed layers to the central point direction thereof. Or

The effective bed layer areas of the plurality of catalyst bed layers decrease gradually layer by layer along the airflow direction, and the method specifically comprises the following steps: according to the trend of the airflow, the reducing catalytic reactor is of a horn-shaped structure with gradually decreasing inner diameter, and the areas of a plurality of catalyst bed layers decrease gradually layer by layer.

Preferably, the number of catalyst beds is from 1 to 10, preferably from 2 to 8, more preferably from 3 to 5.

Preferably, the atomizer is further provided with a water inlet pipeline and a compressed gas inlet pipeline.

Preferably, the gas mixing chamber is further provided with a first gas conveying pipeline.

Preferably, a second gas conveying pipeline is further arranged on the hot air device, and preferably, a combustion-supporting air pipeline is arranged on the second gas conveying pipeline.

Preferably, the purified gas discharge pipeline is further provided with an activated gas discharge pipeline.

Preferably, the system further comprises a GGH heat exchanger. The GGH heat exchanger is arranged on the waste gas inlet pipeline and the purified gas discharge pipeline simultaneously. And on the exhaust gas inlet pipeline, the GGH heat exchanger is positioned between the fourth pipeline and the fifth pipeline. And on the purified gas discharge pipeline, the GGH heat exchanger is positioned between the reducing catalytic reactor and the activated gas discharge pipeline.

In the prior art, the problems of poor low-temperature activity and low CO conversion rate of unit Pt are mainly focused on realizing the low-temperature activity by increasing the content of Pt in a 0 valence state. Our studies show that the activity of the Pt-loaded catalyst is improved, the content of Pt in a 0 valence state is not only improved, but the reaction efficiency can also be improved by improving the dispersity of Pt. Meanwhile, the utilization of Pt is focused on a microscopic level at present, and no applicable reactor is available for the utilization of the Pt-loaded catalyst, so that the utilization rate of the Pt-loaded catalyst is low, and the use cost is increased.

In the invention, by adopting the technical means of combining two-stage ultraviolet induction, in-situ CO reduction pretreatment and the variable-diameter catalytic reactor, the content of Pt with a valence state of 0 can be simultaneously improved, the dispersity of Pt can be improved, the reaction efficiency can be further improved, the utilization rate of the Pt-loaded catalyst can be improved, and the production cost can be reduced.

In the invention, one or more of cordierite, gamma-alumina and mullite are used as a catalyst substrate, and TiO is used₂As the carrier, PtCl is used₄As active component, CoCl is used₂、FeCl₃、MnCl₂As an adjuvant. Then by two-stage ultraviolet induction methodThe synthesis method prepares the highly dispersed CO oxidation catalyst. Firstly, coating carrier slurry on a catalyst substrate, drying and roasting the carrier slurry, and then putting the carrier slurry into PtCl₄And (3) dipping in the solution, irradiating by using ultraviolet light while dipping, drying and roasting the dipped catalyst, and finally activating by using ultraviolet irradiation to obtain the high-dispersion CO oxidation catalyst. Research shows that the core of the Pt-supported catalyst capable of keeping higher activity is the formation of Pt with low coordination number⁰I.e. about 2nm Pt⁰The activity of the nano particles is most suitable for the catalytic oxidation of CO. Therefore, the invention also adopts a mode of metal doping (Co, Fe and Mn) to improve the dispersion of Pt. Then introducing ultraviolet light for irradiation in the impregnation process of the active component, and utilizing the TiO carrier₂Absorbing ultraviolet light, realizing the reduction of Pt with high valence state, and realizing the load of Pt with 0 valence state (in TiO)₂Under the photocatalytic action of (3), electrons are transferred to PtCl₄Reacting part of PtCl₄Reduction reaction is carried out to obtain Pt⁰). Meanwhile, because no dispersant is added in the loading process, the Pt catalyst prepared by the impregnation method contains a plurality of Pt with larger particles⁰(lower coordination number), in practical use, it is not easily bonded to CO, resulting in lower catalytic activity. The Pt can be irradiated by ultraviolet again after the Pt-loaded catalyst is loaded⁰Re-dispersing to re-disperse the large-size Pt⁰To a small size (as shown in fig. 2). At the same time, in TiO₂Part of PtO and PtCl in the catalyst under the photocatalysis of₄Reduction reaction is carried out to obtain Pt⁰(i.e., under the action of electrons, Pt with larger particles is added⁰Conversion to monatomic Pt having a high coordination number⁰). By the method, the Pt loaded with a large amount of monoatomic atoms can be prepared⁰(high coordination number) and containing a small amount of PtO, PtCl₄The catalyst of (1).

In the present invention, the catalyst obtained by two-stage UV induction contains a relatively large amount of small particles of Pt⁰And small amounts of PtO and PtCl₄. In which small particles of Pt⁰The coordination number is high, the catalyst is easy to reoxidize, and the activity can be rapidly reduced after long-term use; due to the high coordination number of the monoatomic atom is easily insertedA substrate, resulting in it and O₂The binding force of (2) is reduced, oxygen is not easily adsorbed and activated, and the catalytic activity of the catalyst cannot reach the maximum. Meanwhile, the adsorption force of CO and PtO is strong, and the combined catalyst is not easy to be oxidized, so that the catalytic efficiency is reduced. PtCl₄Has poor activity and can inhibit the catalysis of CO. Therefore, the morphology of Pt in the catalyst needs to be further optimized. In general, the reduction of PtO to obtain Pt can be achieved by reduction with a reducing gas⁰. A commonly used reducing agent is H₂However, this method can only adjust the valence of Pt, and cannot adjust the particle size of the monoatomic Pt, resulting in reduced Pt⁰The coordination number of the particles is still high (unstable) and is susceptible to reoxidation. The catalyst has found to be more and more efficient in use and by analysis shows small particles of Pt⁰After CO treatment, nanoparticle clustering can occur. Therefore, the invention proposes a mode of pretreatment activation by CO reduction, and the single-atom Pt is adopted⁰Conversion to stable, non-reoxidizable Pt of about 2nm⁰And (3) granules. At the same time, H is introduced in the activation process₂O (water vapor) is dissociated on oxygen vacancies generated by CO activation to form OH, and a large amount of formed OH forms a protective film on the surface of the catalyst, so that CO can be prevented from forming a carbon film and carbonate from covering active sites.

In the invention, the highly dispersed CO oxidation catalyst is pretreated by adopting mixed reducing gas (mixed gas containing water vapor and CO) to strengthen the reaction activity, namely the catalyst is pretreated by utilizing an in-situ activation mechanism, and the method specifically comprises the following steps: the high-temperature hot air at 150-300 ℃ is formed by burning blast furnace gas or coke oven gas of an iron and steel enterprise, and meanwhile, part of the blast furnace gas or coke oven gas is matched with water vapor to pretreat the filled catalyst, so that the Pt-loaded catalyst (high-dispersion CO oxidation catalyst) with high activity is obtained. The invention adopts a CO + water vapor reduction pretreatment mechanism, can simultaneously adjust the valence state and the particle size of Pt, and can adjust the Pt of a single atom⁰Converted into stable, non-reoxidizable, uniform (around 2 nm) sized Pt particles (low coordination number). However, the two CO molecules may generate side reaction to form carbon film and carbonate at a certain temperature, which causes catalysisThe surface of the agent is polluted, but the agent covers reaction sites, and CO is toxic gas, so that a common production workshop has no use right or the used gas cannot be disposed, so that the engineering is difficult to implement. The invention allows for a large number of high purity CO gases in industry, such as blast furnace gas, coke oven gas. Besides being used for heating the catalyst bed layer, part of the gas can be taken out and matched with water vapor to realize the in-situ activation of the catalyst bed layer in a steel plant. Meanwhile, places which need to consume fuel gas, such as sintered charge level injection and iron extraction and zinc reduction rotary kiln, are arranged in the steel plant. Through reasonable pipeline design, secondary pollution caused by CO which is not completely reacted in the activation process can be avoided. According to the invention, a reactor capable of realizing in-situ activation is built, a control system for heat supply and reduction of a catalyst bed layer is built, reaction tail gas can be discharged to a sintering charge level or a rotary kiln, the activation of the catalyst is realized, and further Pt with uniform size is obtained⁰A catalyst.

In the invention, the reducing catalytic reactor is arranged along the airflow direction and keeps the air inlet end at a low space velocity (generally 1000-10000 m)³·h^-1) The air outlet end has high airspeed (generally 3000-30000 m)³·h^-1) And (4) designing a mode. There are two specific modes: 1) the catalyst is placed from a plurality of times, namely along the air inlet direction, the loading amount of the catalyst is gradually reduced, and a blind plate is filled outside the catalytic bed layer at the air outlet end, so that the airflow passes through the bed layer and changes from low airspeed to high airspeed. For example: the number of catalyst loading layers is 4, and the catalyst loading of the first layer should be 2-3 times greater than the catalyst loading of the last layer (as shown in fig. 4 a). 2) Along the direction of the gas flow, by providing a catalytic reactor (similar to a gradually necking trumpet) with a large top and a small bottom, for example: the inner diameter of the outlet of the catalytic reactor is about 1/4-1/3 times of the inner diameter of the inlet, and the catalysts are sequentially filled (as shown in figure 4 b). It should be noted that the temperature of the flue gas at the inlet of the catalyst bed is 130-250 ℃.

Generally, the reactor outlet temperature is higher than the inlet due to the exothermicity of the CO oxidation reaction, and CO is reacted near the outlet at a lower concentration than the inlet. Conventional reactors are generally referred to as SCR reactors, i.e. inlet and outletThe pipe diameters are kept consistent. If the Pt-loaded catalyst also adopts the mode, the catalyst at the outlet end is wasted and cannot be completely utilized, the utilization rate of unit Pt is reduced, and the cost is increased. In the present invention, SO is generated during the actual catalytic reaction of CO₂The catalytic oxidation, the washing of the dust to the catalyst and the catalytic oxidation emit a large amount of heat. Meanwhile, the CO waste gas has the characteristics of high concentration and low temperature. The characteristics require that the flue gas inlet end of the reactor needs to keep higher reaction efficiency and lower flue gas flow velocity, namely lower space velocity, and after the space velocity is reduced, on one hand, the reaction efficiency of a catalyst bed layer can be improved, and the reaction can occur under the low-temperature condition; the sulfur poisoning reaction can be prevented, and the service life of the catalyst is prolonged; in addition, the catalyst can be prevented from being washed by dust under high-speed conditions. After the catalytic reaction, the temperature of the flue gas can be increased, and the concentration of CO can be reduced, so that the reaction efficiency of the catalytic bed layer can be properly reduced, and therefore, only a high airspeed needs to be kept at the flue gas outlet end. After the airspeed at the outlet end is increased, the heat released by the catalytic reaction can be quickly taken away, and the heat accumulation is prevented; and the increased flow rate prevents the conversion of the produced SO₃Reacts with the catalyst.

In the invention, the prepared high-dispersion CO oxidation catalyst is loaded in the reducing catalytic reactor. The inlet valve for the CO off-gas was closed. The method comprises the steps of adopting blast furnace gas or coke oven gas of an iron and steel enterprise to be mixed with air for combustion (a heater) to obtain high-temperature hot air at the temperature of 150-320 ℃, simultaneously mixing part of the blast furnace gas or coke oven gas with water vapor (the water vapor is obtained by atomizing compressed gas (such as compressed nitrogen)), and finally obtaining the high-temperature hot air with the temperature of 150-320 ℃, the CO concentration of 0.3-5 wt%, the water vapor concentration of 3-10 wt%, and O₂Mixed reducing gas with the content of 0. And activating the catalytic bed layer by using the mixed reducing gas, recycling heat after the heat exchange of the treated tail gas is carried out through GGH, and conveying the residual low-temperature waste gas to a sintering charge level or a rotary kiln through an activated smoke discharge port. And continuously reacting for 1-5 h to obtain the activated catalyst. According to the invention, the reaction system is optimally designed, and the heater is arranged in front of the GGH, so that the high-efficiency utilization of heat is realized.

Compared with the prior art, the invention has the following beneficial technical effects:

1: the invention creatively adopts a new two-stage ultraviolet coupling CO pretreatment method, greatly improves the dispersity of Pt, and can obtain the medium-scale Pt with uniform morphological distribution⁰The particles (about 2 nm) greatly improve the reactivity and the resistance to poisoning of the catalyst. Compared with a single ultraviolet irradiation preparation technology, the irradiation stage after roasting can be beneficial to improving the dispersity of Pt. Compared with a single CO pretreatment technology, the prepared dispersed meso-scale Pt⁰More particles and higher catalytic activity.

2: the invention fully utilizes the CO source characteristics of the steel plant and the characteristic requirements of the furnace kiln, and solves the engineering problem that CO is difficult to be applied to catalyst activation. Greatly reducing the production cost. The utilization efficiency of the flue gas is improved.

3: in the activation stage of the CO oxidation catalyst, the catalyst is activated by adopting the CO and water vapor mixed reducing gas, and on one hand, the monatomic Pt can be used⁰Conversion to stable, non-reoxidizable Pt of about 2nm⁰Particles; on the other hand by introducing H₂O (water vapor) can form an OH protective film on the surface of the catalyst, and prevent CO from forming a carbon film and carbonate from covering active sites.

4: according to the invention, through researching and simulating the heat release rule of the catalytic bed, the CO oxidation reaction rate is controlled in a targeted manner, and the design of the reducing catalytic reactor is combined, so that the fixed-point reaction of CO is realized, the utilization rate of Pt in the whole catalytic bed is improved, the service life is prolonged, the local temperature rise of the catalyst layer is prevented, and the occurrence of catalyst poisoning reaction is inhibited.

Drawings

FIG. 1 is a flow diagram of the preparation of the highly dispersed CO oxidation catalyst of the present invention.

FIG. 2 shows the present invention employing UV irradiation to irradiate Pt⁰Schematic of the mechanism of redispersion.

FIG. 3 is a schematic structural diagram of an exhaust gas treatment system based on a variable diameter catalytic reactor according to the present invention.

FIG. 4a is a schematic view of a step distribution when a blind plate is disposed in a catalyst bed.

FIG. 4b is a schematic view of a stepwise decreasing catalyst bed distribution.

FIG. 5 is a schematic diagram of the mechanism of different airspeeds at the inlet and outlet of the variable-diameter catalytic reactor of the present invention.

FIG. 6 comparison of low temperature oxidation activity of catalysts before and after UV irradiation.

Reference numerals: 1: a reducing gas preparation unit; 101: an atomizer; 102: a gas mixing chamber; 103: a hot air device; 104: a water inlet pipe; 105: a compressed gas inlet conduit; 106: a first gas delivery conduit; 107: a second gas delivery conduit; 108: a combustion air duct; 2: a variable diameter catalytic reactor; 201: a catalyst bed layer; 202: a blind plate; 3: a GGH heat exchanger; l1: an exhaust gas inlet conduit; l2: a purge gas discharge conduit; l3: a third pipeline; l4: a fourth conduit; l5: a fifth pipeline; l6: and (5) discharging the activated gas to a pipeline.

Detailed Description

The technical solution of the present invention is illustrated below, and the claimed scope of the present invention includes, but is not limited to, the following examples.

A highly dispersed CO oxidation catalyst, the catalyst being prepared by: the catalyst substrate coated with the support layer is first impregnated in an auxiliary agent, and the impregnation is completed and heat treated. Then the catalyst substrate is put into the active component for impregnation under the condition of ultraviolet irradiation, and heat treatment is carried out again after the impregnation is finished. And finally, carrying out light treatment on the catalyst substrate by adopting ultraviolet light to obtain the high-dispersion CO oxidation catalyst.

Preferably, the matrix is a high temperature resistant mineral material. Preferably one of cordierite, gamma-alumina, and mullite.

Preferably, the support is titanium dioxide.

Preferably, the content of anatase titania in the titania is 75 to 100%, preferably 80 to 100%. The mesoporous aperture is 5-40 nm, preferably 10-20 nm. The surface area is 50-200m²Per g, preferably from 60 to 100m²(ii) in terms of/g. The average particle size is 2 to 10 μm,preferably 5 to 8 μm.

Preferably, the active component is platinum tetrachloride.

Preferably, the auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt. Preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

Preferably, the ratio of the content of the carrier to the volume of the matrix is 100-300g/L, preferably 150-200g/L, and more preferably 170-190 g/L.

Preferably, the adjuvant is present in an amount of 0 to 10 wt%, preferably 0.1 to 7 wt%, more preferably 0.1 to 3 wt% of the mass of the carrier.

Preferably, the active ingredient is present in an amount of 0.05 to 1 wt%, preferably 0.08 to 0.5 wt%, more preferably 0.1 to 0.3 wt% of the mass of the carrier.

Preferably, the heat treatment is a drying and then baking treatment.

Preferably, the wavelength of the ultraviolet light is 280-400 nm, preferably 300-400 nm.

A method of preparing a highly dispersed CO oxidation catalyst, the method comprising the steps of:

1) the carrier is coated on the surface of the substrate and then heat-treated to obtain the catalyst substrate with the carrier layer.

2) The catalyst substrate having the support layer is immersed in a solution containing an assistant and then subjected to heat treatment to obtain a catalyst substrate having a support layer supporting an assistant.

3) Under the condition of ultraviolet irradiation, the catalyst substrate with the loading assistant carrier layer is put into a solution containing active components for dipping, then heat treatment is carried out, and finally light treatment is carried out through ultraviolet light, so that the high-dispersion CO oxidation catalyst is obtained.

Preferably, the matrix is a high temperature resistant mineral material. Preferably one of cordierite, gamma-alumina, and mullite.

Preferably, the support is titanium dioxide. Preferably, the titanium dioxide has an anatase content of 75 to 100%, preferably 80 to 100%. Its mesoporous poresThe diameter is 5 to 40nm, preferably 10 to 20 nm. The surface area is 50-200m²Per g, preferably from 60 to 100m²(ii) in terms of/g. The average particle size is 2 to 10 μm, preferably 5 to 8 μm.

Preferably, the active component is platinum tetrachloride.

Preferably, the auxiliary agent is one or more of soluble cobalt salt, iron salt or manganese salt. Preferably CoCl₂、FeCl₃、MnCl₂One or more of (a).

Preferably, in step 1), the coating of the carrier on the surface of the substrate is specifically: adding TiO into the mixture₂The powder, silica sol, and water are mixed to prepare a slurry, which is then poured onto the substrate and cured (e.g., dried, baked, roasted, etc.). The thickness of the washcoat after washcoat was about 50-500 μm.

Preferably, the heat treatment is a drying treatment and then a baking treatment. Wherein the drying temperature is 60-150 ℃, preferably 80-120 ℃, and the drying time is 0.2-8 h, preferably 0.5-5 h.

Preferably, the roasting temperature is 300-800 ℃, and preferably 400-600 ℃. The roasting time is 0.3-10 h, preferably 0.5-8 h.

Preferably, in the step 3), the wavelength of the ultraviolet light is 280 to 400nm, and preferably 300 to 400 nm.

Wherein, the time of the first ultraviolet irradiation is 0.3 to 5 hours, preferably 0.5 to 3 hours. The temperature is 20 to 120 ℃, preferably 25 to 100 ℃.

The time of the second ultraviolet light treatment is 0.3-5 h, preferably 0.5-3 h. The temperature is 20 to 120 ℃, preferably 25 to 100 ℃.

The highly dispersed CO oxidation catalyst is used for treating waste gas containing low-concentration CO, preferably sintering flue gas, tail gas of a rotary kiln for extracting iron and reducing zinc, and tail gas of soot of a steel rolling heating furnace.

Preferably, in the low concentration CO-containing exhaust gas: the concentration of CO is 4000-20000 mg/m³Preferably 4500-18000 mg/m³More preferably 5000 to 15000mg/m³。

Preferably, SO₂The concentration of (A) is 0 to 1000mg/m³Preferably 30 to 800mg/m³More preferably 50 to 500mg/m³。

Preferably, H₂The concentration of O is 1 to 30 wt%, preferably 3 to 25 wt%, and more preferably 5 to 20 wt%.

Preferably, the temperature of the waste gas is 100-220 ℃, preferably 110-200 ℃, and more preferably 120-170 ℃.

Preferably, the treatment of the waste gas containing low concentration of CO by using the high-dispersion CO oxidation catalyst is as follows:

s1) closing an air inlet valve of the waste gas containing low-concentration CO, opening a reducing gas inlet valve, and activating the high-dispersion CO oxidation catalyst by using the reducing gas to obtain the activated high-dispersion CO oxidation catalyst.

S2) closing the reducing gas inlet valve, opening the inlet valve of the waste gas containing low-concentration CO, and treating the waste gas containing low-concentration CO by using the activated high-dispersion CO oxidation catalyst to obtain purified gas.

Preferably, the reducing gas is a mixed gas containing water vapor and CO. The temperature of the reducing gas is 150-320 ℃, and preferably 170-300 ℃. The activation treatment time is 1 to 5 hours, preferably 1.5 to 4 hours.

Preferably, the concentration of CO in the reducing gas is 0.3 to 5 wt%, preferably 0.5 to 3 wt%. The concentration of the water vapor in the reducing gas is 0 to 10 wt%, preferably 0.3 to 8 wt%.

Preferably, the reducing gas is prepared by the following method: atomizing water by compressed gas to obtain water vapor. Meanwhile, part of the coal gas is mixed with air to be combusted to obtain hot air. And finally, mixing part of the coal gas, hot air and water vapor to obtain the reducing gas.

Preferably, the gas is blast furnace gas and/or coke oven gas. The compressed gas is compressed nitrogen.

Example 1

As shown in fig. 3, the exhaust gas treatment system based on the variable diameter catalytic reactor comprises an exhaust gas inlet pipeline L1, a reducing gas preparation unit 1, a variable diameter catalytic reactor 2 and a purified gas discharge pipeline L2. The waste gas inlet pipeline L1 is communicated with the gas inlet of the waste gas catalytic device 2, and the exhaust port of the reducing catalytic reactor 2 is communicated with the purified gas discharge pipeline L2. In the reducing catalytic reactor 2, a plurality of catalyst beds 201 are arranged according to the trend of the airflow, and the effective bed areas of the plurality of catalyst beds 201 decrease gradually layer by layer along the trend of the airflow.

Example 2

Example 1 was repeated except that the reducing gas preparing unit 1 included the atomizer 101, the gas mixing chamber 102, and the hot air device 103. The exhaust port of the atomizer 101 is communicated with the intake port of the gas mixing chamber 102 through a third pipeline L3. The exhaust port of the gas mixing chamber 102 is communicated with the exhaust gas inlet pipeline L1 through a fourth pipeline L4. The exhaust port of the hot air device 103 is communicated with an exhaust gas inlet pipeline L1 through a fifth pipeline L5.

Example 3

Example 2 is repeated, except that the effective bed areas of the plurality of catalyst beds 201 decrease gradually layer by layer along the airflow direction: the reducing catalytic reactor 2 is of a cylindrical structure, the sizes of a plurality of catalyst beds 201 are consistent, and blind plates 202 are arranged in the plurality of catalyst beds 201. According to the trend of the gas flow, the areas of the blind plates 202 in the plurality of catalyst beds 201 increase gradually layer by layer, and the increasing mode of the areas of the blind plates 202 is that the areas gradually increase gradually layer by layer from the edges of the plurality of catalyst beds 201 to the central point thereof.

Example 4

Example 2 is repeated, except that the effective bed areas of the plurality of catalyst beds 201 decrease gradually layer by layer along the airflow direction: according to the trend of the air flow, the reducing catalytic reactor 2 is in a horn-shaped structure with gradually decreasing inner diameter, and the areas of a plurality of catalyst bed layers 201 are gradually decreased layer by layer.

Example 5

Example 3 was repeated as shown in fig. 4a, except that the number of catalyst beds 201 was 4.

Example 6

Example 4 was repeated as shown in fig. 4b, except that the number of catalyst beds 201 was 4.

Example 7

Example 6 is repeated, as shown in fig. 3, except that the atomizer 101 is further provided with a water inlet pipe 104 and a compressed gas inlet pipe 105.

Example 8

Example 7 is repeated, except that the gas mixing chamber 102 is further provided with a first gas conveying pipeline 106.

Example 9

Example 8 is repeated, except that a second gas conveying pipeline 107 is further arranged on the hot air device 103, and a combustion-supporting air pipeline 108 is arranged on the second gas conveying pipeline 107.

Example 10

Example 9 was repeated except that the purge gas discharge line L2 was further provided with an activated gas discharge line L6.

Example 11

Example 10 was repeated except that the system further included a GGH heat exchanger 3. The GGH heat exchanger 3 is provided on both the exhaust gas inlet line L1 and the purge gas discharge line L2. Wherein, on the exhaust gas inlet line L1, the GGH heat exchanger 3 is located between the fourth line L4 and the fifth line L5. On the purge gas discharge line L2, the GGH heat exchanger 3 is located between the variable diameter catalytic reactor 2 and the activated gas discharge line L6.

Method example 1

A method of preparing a highly dispersed CO oxidation catalyst, the method comprising the steps of:

1) adding TiO into the mixture₂Coating on the surface of a substrate, and then performing heat treatment to obtain the titanium-doped titanium dioxide₂The catalyst substrate of the layer.

2) Will have TiO₂The catalyst substrate of the layer is immersed in a solution containing an assistant and then subjected to heat treatment to obtain a catalyst substrate having an assistant-supporting layer.

3) Under the condition of ultraviolet irradiation, a catalyst substrate with a supporting layer of a loading auxiliary agent is put into a PtCl-containing carrier layer₄The solution of (a) is dipped, then heat treatment is carried out, finally light treatment is carried out by ultraviolet light,a highly dispersed CO oxidation catalyst is obtained.

Method example 2

A method for treating a low concentration CO-containing exhaust gas with a highly dispersed CO oxidation catalyst, the method comprising the steps of:

s1) closing an air inlet valve of the waste gas containing low-concentration CO, opening a reducing gas inlet valve, and activating the high-dispersion CO oxidation catalyst by using the reducing gas to obtain the activated high-dispersion CO oxidation catalyst.

S2) closing the reducing gas inlet valve, opening the inlet valve of the waste gas containing low-concentration CO, and treating the waste gas containing low-concentration CO by using the activated high-dispersion CO oxidation catalyst to obtain purified gas.

Preparation of example 1

Adding TiO into the mixture₂Coating the slurry on cordierite substrate, drying at 95 deg.C for 2.5 hr, and calcining at 500 deg.C for 3.5 hr to obtain TiO₂A catalyst substrate having a coating thickness of 100 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at the temperature of 95 ℃ for 2.5 hours and then roasted at the temperature of 500 ℃ for 3.5 hours. Then, under the irradiation of ultraviolet light and at the temperature of 30 ℃, the catalyst substrate is put into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2.5h at the temperature of 95 ℃, then roasted for 3.5h at the temperature of 500 ℃, and then treated by ultraviolet irradiation for 2h at the temperature of 30 ℃, so that the high-dispersion CO oxidation catalyst I with the Pt loading of about 0.1 wt% (based on the mass of the carrier) is obtained.

Preparation of example 2

Adding TiO into the mixture₂Coating the slurry on a gamma-alumina substrate, drying at 100 deg.C for 2.5h, and calcining at 550 deg.C for 3h to obtain TiO₂A catalyst substrate having a coating thickness of 150 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at 100 ℃ for 2h and then calcined at 520 ℃ for 3.5 h. Then in violetIrradiating with external light at 30 deg.C, and placing the catalyst substrate into a container containing PtCl₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2h at the temperature of 100 ℃, then roasted for 3h at the temperature of 550 ℃, and then treated for 2h at the temperature of 30 ℃ by adopting ultraviolet irradiation, so that the high-dispersion CO oxidation catalyst II with the Pt loading of about 0.15 wt% (based on the mass of the carrier) is obtained.

Preparation of example 3

Adding TiO into the mixture₂Coating the slurry on a mullite substrate, drying at 100 ℃ for 2.5h, and roasting at 600 ℃ for 3h to obtain TiO₂A catalyst substrate having a coating thickness of 50 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at 100 ℃ for 2h and then roasted at 550 ℃ for 3.5 h. Then under the irradiation of ultraviolet light and at the temperature of 40 ℃, putting the catalyst substrate into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2h at the temperature of 100 ℃, then roasted for 3h at the temperature of 600 ℃, and then treated for 2h at the temperature of 40 ℃ by adopting ultraviolet irradiation, so that the high-dispersion CO oxidation catalyst III with the Pt loading of about 0.05 wt% (based on the mass of the carrier) is obtained.

Comparative preparation example 1

Adding TiO into the mixture₂Coating the slurry on cordierite substrate, drying at 95 deg.C for 2.5 hr, and calcining at 500 deg.C for 3.5 hr to obtain TiO₂A catalyst substrate having a coating thickness of 100 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at the temperature of 95 ℃ for 2.5 hours and then roasted at the temperature of 500 ℃ for 3.5 hours. Then putting the catalyst substrate into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2.5h at the temperature of 95 ℃, then roasted for 3.5h at the temperature of 500 ℃, and then treated for 2h by ultraviolet irradiation at the temperature of 30 ℃, so that the high-dispersion CO oxidation catalyst Ic with the Pt loading of about 0.1 wt% (based on the mass of the carrier) is obtained.

Comparative preparation example 2

Adding TiO into the mixture₂Coating the slurry on a gamma-alumina substrate, drying at 100 deg.C for 2.5h, and calcining at 550 deg.C for 3h to obtain TiO₂A catalyst substrate having a coating thickness of 150 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at 100 ℃ for 2h and then calcined at 520 ℃ for 3.5 h. Then putting the catalyst substrate into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2h at the temperature of 100 ℃, then roasted for 3h at the temperature of 550 ℃, and then treated for 2h at the temperature of 30 ℃ by adopting ultraviolet irradiation, so that the high-dispersion CO oxidation catalyst IIc with the Pt loading of about 0.15 wt% (based on the mass of the carrier) is obtained.

Comparative preparation example 3

Adding TiO into the mixture₂Coating the slurry on a gamma-alumina substrate, drying at 100 deg.C for 2.5h, and calcining at 550 deg.C for 3h to obtain TiO₂A catalyst substrate having a coating thickness of 150 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at 100 ℃ for 2h and then calcined at 520 ℃ for 3.5 h. Then, under the irradiation of ultraviolet light and at the temperature of 30 ℃, the catalyst substrate is put into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is completed, the drying is continued for 2h at the temperature of 100 ℃ and then the calcination is carried out for 3h at the temperature of 550 ℃ to obtain the highly dispersed CO oxidation catalyst IIIc with the Pt loading of about 0.15 wt% (based on the mass of the carrier).

Comparative preparation example 4

Adding TiO into the mixture₂Coating the slurry on cordierite substrate, drying at 95 deg.C for 2.5 hr, and calcining at 500 deg.C for 3.5 hr to obtain TiO₂A catalyst substrate having a coating thickness of 100 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃、MnCl₂The mixed assistant solution of (4) is impregnated. After the impregnation is finished, the mixture is dried for 2.5 hours at the temperature of 95 ℃ and then baked at the temperature of 500 DEG CAnd (5) burning for 3.5 h. Then putting the catalyst substrate into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the drying is continued for 2.5h at the temperature of 95 ℃ and then the roasting is continued for 3.5h at the temperature of 500 ℃, thus obtaining the highly dispersed CO oxidation catalyst IVc with the Pt loading of about 0.1 wt% (based on the mass of the carrier).

Comparative preparation example 5

Adding TiO into the mixture₂Coating the slurry on a mullite substrate, drying at 100 ℃ for 2.5h, and roasting at 600 ℃ for 3h to obtain TiO₂A catalyst substrate having a coating thickness of 50 μm; continuing to put the catalyst substrate into the container containing CoCl₂、FeCl₃The mixed assistant solution of (4) is impregnated. After the impregnation is completed, the mixture is dried at 100 ℃ for 2h and then roasted at 550 ℃ for 3.5 h. Then under the irradiation of ultraviolet light and at the temperature of 40 ℃, putting the catalyst substrate into the PtCl-containing solution₄Is immersed in the solution of (2) for 2 h. After the impregnation is finished, the catalyst is continuously dried for 2 hours at the temperature of 100 ℃ and then roasted for 3 hours at the temperature of 600 ℃ to obtain the high-dispersion CO oxidation catalyst Vc with the Pt loading of about 0.05 wt% (based on the mass of the carrier).

Application example 1

Raw flue gas: the concentration of CO is 14459mg/m³，SO₂Has a concentration of 622mg/m³，H₂The O concentration was 14.2 wt% and the temperature was 151 ℃.

Reducing gas: CO concentration 3.8 wt%, water vapor concentration 7.9 wt%, O₂The content is 0 and the temperature is 230 ℃.

And (3) treating the raw flue gas by adopting a waste gas treatment system based on a variable-diameter catalytic reactor. The highly dispersed CO oxidation catalysts I to III prepared in preparation examples 1 to 3 and the highly dispersed CO oxidation catalysts Ic to IVc prepared in comparative preparation examples 1 to 4 were simultaneously filled in the catalyst bed layer in sequence, and the raw flue gas was treated.

Firstly, closing an air inlet valve of the original flue gas, then opening a reducing gas inlet valve, and firstly, adopting the reducing gas to activate the highly dispersed CO oxidation catalyst to obtain the activated highly dispersed CO oxidation catalyst; and after 3h, closing the reducing gas inlet valve, opening the original flue gas inlet valve, and treating the waste gas containing low-concentration CO (namely the original flue gas) by using the activated high-dispersion CO oxidation catalyst to obtain purified gas. The treatment effect of each catalyst on the smoke is compared and shown in the table 1:

table 1:

note: t is₁₀₀Refers to the reaction temperature at which the CO conversion reaches 100%. In general T₁₀₀The lower the temperature, the stronger the low temperature catalytic activity of the catalyst.

Application example 2

Raw flue gas: the concentration of CO is 14459mg/m³，SO₂Has a concentration of 622mg/m³，H₂The O concentration was 14.2 wt% and the temperature was 151 ℃.

Reducing gas: h₂Concentration of 3.8 wt%, water vapor concentration of 7.9 wt%, O₂The content is 0 and the temperature is 230 ℃.

And (3) treating the raw flue gas by adopting a waste gas treatment system based on a variable-diameter catalytic reactor. The highly dispersed Pt-loaded catalysts I to III prepared in preparation examples 1 to 3 and the highly dispersed Pt-loaded catalysts Ic to IVc prepared in comparative preparation examples 1 to 4 were simultaneously sequentially packed into the catalyst bed, and the raw flue gas was treated.

Firstly, closing an air inlet valve of the original flue gas, then opening a reducing gas inlet valve, and firstly, adopting the reducing gas to activate the highly dispersed CO oxidation catalyst to obtain the activated highly dispersed CO oxidation catalyst; and after 3h, closing the reducing gas inlet valve, opening the original flue gas inlet valve, and treating the waste gas containing low-concentration CO (namely the original flue gas) by using the activated high-dispersion CO oxidation catalyst to obtain purified gas. The treatment effect of each catalyst on the flue gas is compared and shown in the table 2:

table 2: