A catalyst for carbon monoxide oxidation reaction and preparation method thereof

Abstract

The invention discloses a catalyst for carbon monoxide oxidation reaction and a preparation method thereof. High dispersion of the silver catalyst is achieved under the combined action of an oxygen-rich reaction atmosphere and a hydroxyl group on the surface of a carrier, the mass fraction of silver in the catalyst is 0.1-10%, and the carrier is surface hydroxylated silicon dioxide; the catalyst is applied to carbon monoxide oxidation reaction under oxygen-rich conditions, organic matter oxidation elimination, automobile / blast furnace exhaust gas purification and other reactions. The catalyst can efficiently catalyze carbon monoxide oxidation reaction under a wide temperature window (room temperature to 600°C), operate for a long time (more than 1000h) at high temperature without deactivation, and can maintain excellent performance under the presence of carbon dioxide, water vapor, alkanes and the like. The catalyst uses the reaction atmosphere to induce the production of highly dispersed active components in situ and maintains its high activity and stability. The preparation method is simple and easy to scale up, and has broad application prospects in automobile exhaust elimination, environmental purification and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic oxidation, and in particular relates to a catalyst used for carbon monoxide oxidation reaction and automobile / blast furnace tail gas purification and a preparation method thereof. Background Art

[0002] Since humans entered the era of internal combustion engines, cars have replaced traditional horse-drawn carriages as the main means of social transportation. The emission of automobile exhaust containing a large amount of pollutants such as carbon monoxide and hydrocarbons has caused serious environmental pollution problems. How to efficiently treat automobile exhaust pollutants such as carbon monoxide and hydrocarbons to eliminate environmental pollution has attracted more and more attention. The main method for treating carbon monoxide in exhaust gas is to use the carbon monoxide oxidation reaction (2CO+O 2 =2CO 2 )Eliminate carbon monoxide and convert it into carbon dioxide which is harmless to the human body.

[0003] At present, the most commonly used three-way catalysts in automobile exhaust treatment devices usually use precious metals Pt, Rh, and Pd as active components. The temperature of automobile engine exhaust is generally between 200 and 400°C. Under such high-temperature reaction conditions, the precious metal catalyst as an active component is prone to nanoparticle sintering, which reduces the specific surface area of ​​the active component and thus deactivates the catalyst. The use of precious metals has also greatly increased the cost of automobile exhaust treatment. At the same time, there is a huge temperature difference between the start-stop and continuous operation of the engine exhaust. The catalyst needs to be able to efficiently catalyze the complete oxidation of carbon monoxide in the low-temperature to high-temperature range. Therefore, the development of a catalyst that efficiently catalyzes the oxidation of carbon monoxide in a wide temperature range from low temperature to high temperature and resists sintering at high temperatures is the key and difficulty of the research.

[0004] A lot of research has been done to improve the sintering resistance of precious metal catalysts. Currently, the methods that are being studied include using porous oxides or thin layers of boron nitride to encapsulate precious metal nanoparticles such as Pt and Au, and selecting suitable carriers (such as CeO 2 , molecular sieves, etc.) to enhance the interaction between metal particles and the carrier surface. These methods can effectively suppress the sintering problem of metal particles. However, the former improves the stability of active metal components at the expense of activity; the latter's overly strong metal-carrier interaction will reduce the reaction activity of the catalyst in the low temperature section, while the weaker metal-carrier interaction cannot avoid the sintering of metal particles in the actual exhaust gas treatment reaction. Traditionally, the use of particle encapsulation or strong metal-carrier interaction has high requirements for the catalyst preparation process, making it difficult to achieve large-scale preparation of catalysts and not suitable for industrial promotion and application. Summary of the invention

[0005] Considering the current status of the development of carbon monoxide oxidation reaction and automobile / blast furnace exhaust purification catalysts, in order to overcome the defects of the prior art, the present invention has developed a preparation method for a highly active silver catalyst supported on silica induced activated by an oxygen-rich reaction atmosphere, which can be used to catalyze carbon monoxide oxidation reaction, automobile exhaust purification, blast furnace exhaust purification and other reactions. The catalyst is designed based on the reaction conditions of automobile exhaust purification, directly activates and stabilizes highly active Ag nanoclusters under the reaction atmosphere, and efficiently catalyzes oxidation reactions in a wide temperature window (room temperature to 600°C). At the same time, it has very excellent high-temperature stability and has no activity loss during long-term operation at high temperatures.

[0006] To achieve the above objectives, the present invention provides a method for preparing a catalyst for carbon monoxide oxidation reaction, which utilizes an oxidizing reaction atmosphere to in-situ induce the production of highly dispersed active components, wherein the catalyst uses silicon dioxide as a carrier and metal Ag as an active component.

[0007] The reaction atmosphere used to induce the generation of active components is an oxygen-rich catalytic oxidation reaction atmosphere.

[0008] The method comprises the following steps:

[0009] (1) calcining the support at 450-550° C. for 5 h;

[0010] (2) mechanically mixing the silver-containing solid precursor with the calcined carrier and grinding them thoroughly to obtain a mixture of the silver-containing precursor and the carrier;

[0011] (2) The mixture obtained in step (2) is calcined at 300-500° C. for 2-10 h in an oxygen-rich atmosphere to obtain Ag / SiO 2 catalyst.

[0012] The silver-containing precursor is silver powder or silver oxide powder; the particle size of the powder is 1nm-1μm.

[0013] The oxygen-rich atmosphere is pure O 2 , O with different concentrations diluted by inert gas 2 , O 2 At least one of the reaction gases having a volume ratio with CO ≥ 1.

[0014] Another aspect of the present invention provides a catalyst prepared by the above preparation method, wherein the mass fraction of metal Ag in the catalyst is 0.1% to 10% of the carrier, and the metal particle size is 0.3 to 2 nm.

[0015] The size of the metal active components is regulated by changing the oxygen concentration of the processing atmosphere; the higher the oxygen concentration, the smaller the size of the metal active components.

[0016] The surface of the carrier has surface hydroxyl groups, including isolated hydroxyl groups and coupled hydroxyl groups.

[0017] In another aspect, the present invention provides the use of the supported Ag catalyst in carbon monoxide oxidation reaction, oxidation elimination of gaseous organic matter, and automobile / blast furnace tail gas purification.

[0018] The advantages of the present invention compared with the prior art are:

[0019] A highly stable and active silica-supported Ag catalyst was obtained by inducing activation using a reaction atmosphere. The catalyst exhibited good high-temperature anti-sintering performance in carbon monoxide oxidation reactions and automobile exhaust purification, and did not deactivate after long-term operation at high temperatures. It also exhibited excellent catalytic activity for carbon monoxide oxidation reactions within a wide temperature window (room temperature to 600°C). This method is the first publicly reported method for preparing Ag-based catalysts that uses an oxygen-rich reaction atmosphere to induce activation and stabilize active components. The method is simple and easy to scale up, and has great potential for application in automobile exhaust purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0021] Figure 1 The Ag of the silver-containing precursor with 5% Ag loading in Example 1 2 O-SiO 2 Before the mixture is activated under the reaction atmosphere (Ag 2 O-SiO 2 ) (Ag / SiO 2 ), wherein a is an X-ray diffraction pattern and b is an X-ray photoelectron spectrum;

[0022] Figure 2 The Ag of the silver-containing precursor with 5% Ag loading in Example 1 2 O-SiO 2 Spherical aberration electron microscopy images of the mixture before and after activation in the reaction atmosphere, where a is the aberration before activation (Ag 2 O-SiO 2 ), b is after activation (Ag / SiO 2 );

[0023] Figure 3 The Ag of the silver-containing precursor with 5% Ag loading in Example 2 2 O-SiO 2 Comparison of catalytic reaction performance of the mixture before and after activation in the reaction atmosphere;

[0024] Figure 4 The Ag of the silver-containing precursor with 5% Ag loading described in Example 32 O-SiO 2 Mixtures in different O 2 Comparison of catalytic reaction performance after activation in reaction atmosphere of concentration;

[0025] Figure 5 5% Ag / SiO after activation as described in Example 4 2 Catalytic activity of the catalyst in a wide temperature window (room temperature to 600°C);

[0026] Figure 6 The activated 5% Ag / SiO 2 Catalyst long-term operation stability diagram;

[0027] Figure 7 5% Ag / SiO after activation as described in Examples 6 and 7 2 Catalytic activity and stability diagram of the catalyst at high reaction space velocity; a is the catalytic activity of the catalyst at different temperatures, and b is 5600000 mL / g cat ·h, catalyst stability diagram at different operating times, c is 1200000mL / g cat ·h, catalyst stability diagram at different operating times;

[0028] Figure 8 5% Ag / SiO after activation as described in Examples 8, 9, and 10 2 The catalyst contains CO 2 and C 3 H 6 The catalytic activity and stability diagram in the carbon monoxide reaction atmosphere; wherein a is the catalytic activity of the catalyst at different temperatures, b is the catalyst stability diagram at different operating times at 500°C, and c is the catalyst stability diagram at different operating times at 80°C;

[0029] Fig. 9 5% Ag / SiO after activation as described in Examples 11 and 12 2 The catalyst contains CO 2 , CH 4 , H 2 The catalytic activity and stability diagram of O in the simulated automobile exhaust atmosphere; a is the catalytic activity of the catalyst at different temperatures, and b is the catalyst stability diagram at different operating times;

[0030] Fig.10 5% Ag / SiO after activation as described in Example 13 2 Activity diagram of catalyst for formaldehyde elimination;

[0031] Fig.11 5% Ag / Al after activation as described in Comparative Example 12 O 3 Catalytic reaction performance diagram of the catalyst;

[0032] Fig.12 The 5% Ag / SiO 2 -Chart of catalytic reaction performance of uncalcined catalyst before and after activation. DETAILED DESCRIPTION

[0033] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0034] The present invention is further described in detail below through implementation cases. This implementation case is implemented based on the technology of the present invention, and a detailed implementation method and specific operation process are now given to illustrate that the present invention is creative, but the protection scope of the present invention is not limited to the following examples.

[0035] Example 1

[0036] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0037] (2) Take 50 mg of the silver-containing precursor mixture obtained in step (1) and stir in 1% CO / 20% O 2 / 79%N 2 In the atmosphere, the flow rate was 10 ml / min, and the temperature was raised to 500°C at 1°C / min and maintained for 2 h to obtain the reaction-activated Ag / SiO 2 catalyst.

[0038] The silver-containing precursor Ag obtained above 2 O-SiO 2 Mixture and activated Ag / SiO 2 The catalyst was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. Figure 1 As shown by Figure 1 It can be seen that the silver-containing precursor Ag before activation 2 O-SiO 2 There are large particles of Ag and Ag in the mixture 2 O, reactive Ag / SiO 2 The catalyst contains highly dispersed silver species. Figure 2 As shown by Figure 2 It can be seen that the high-resolution transmission electron microscopy results also show that the Ag / SiO2 The catalysts are mainly composed of sub-nanometer clusters, which indicates that the oxygen-rich reaction atmosphere can induce Ag and Ag 2 O large particles in SiO 2 The surface of the carrier is dispersed into sub-nanometer clusters.

[0039] Example 2

[0040] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0041] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / 79%N 2 Reaction gas, adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and maintain for 2h;

[0042] (3) After cooling to room temperature, the temperature was raised to 500°C at a rate of 1°C / min. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0043] Figure 3 The silver-containing precursor Ag with a Ag loading of 5% in Example 2 2 O-SiO 2 The activity of the mixture before and after activation for carbon monoxide oxidation reaction. It can be seen that the catalyst has no obvious activity below 250℃ before activation. After activation with 500℃ reaction gas, the activity of the catalyst in the low temperature section is significantly improved. This shows that the use of oxygen-rich reaction atmosphere to activate Ag / SiO 2 The method of using the catalyst for carbon monoxide oxidation reaction is simple and easy, and the effect is remarkable.

[0044] Example 3

[0045] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0046] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / x% O 2 / N 2 Balance reaction gas (x = 0.5, 5, 20) and pure O 2 , adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0047] (3) After cooling to room temperature, cut into 1% CO / 20% O 2 / 79%N 2 The reaction gas was then heated to 500°C at a rate of 1°C / min. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0048] Figure 4 The silver-containing precursor Ag with a Ag loading of 5% in Example 3 2 O-SiO 2 Mixtures in different O 2 The activity of carbon monoxide oxidation reaction after activation in the activated atmosphere. 2 The increase in concentration promotes the activity of the activated catalyst. 2 This indicates that the Ag / SiO 2 The catalyst method is feasible in the process of automobile exhaust purification.

[0049] Example 4

[0050] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0051] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to 1°C / min and raise the temperature to 500°C and hold for 4 h;

[0052] (3) Cool down to room temperature. After three cycles of heating and cooling, the temperature is raised from room temperature to 500°C at a rate of 1°C / min. The reactants and products are analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0053] Figure 5 The silver-containing precursor Ag with a Ag loading of 5% in Example 4 2 O-SiO 2 The mixture was activated multiple times in the reaction gas to test its activity in the carbon monoxide oxidation reaction. It can be seen that after being fully activated by the reaction atmosphere, the catalyst can completely convert CO at room temperature, and the catalyst is not deactivated until 550°C. The temperature range for complete conversion of CO is between 25 and 550°C, and there is a temperature range of 500°C. This shows that the prepared Ag / SiO 2 The catalyst is suitable for carbon monoxide oxidation reaction at different temperatures.

[0054] Example 5

[0055] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0056] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 120000mL / g cat h, control the heating rate to be 1℃ / min and heat to 400℃ and keep it for 2h;

[0057] (3) After cooling to room temperature, the temperature was raised to 300°C at a rate of 1°C / min and maintained for 1000 h. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0058] Figure 6 The activated 5% Ag / SiO 2 The catalyst was run for a long time at 300℃ and 120000mL / g cat h space velocity, and no deactivation was observed during continuous operation for a long time (1000 h). 2 The catalyst has excellent anti-sintering performance.

[0059] Example 6

[0060] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0061] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas, adjust the mass space velocity to 12000mL / gcat·h, control the heating rate to 1℃ / min and raise the temperature to 500℃ and hold for 2h;

[0062] (3) After cooling to room temperature, the mass space velocity was adjusted to 1,200,000 and 5,600,000 mL / gcat·h, and the temperature was raised to 350°C and 400°C at a rate of 1°C / min, respectively. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0063] Figure 7 The Ag / SiO2 with an activated Ag loading of 5% as described in Example 6 2 The activity of the catalyst for high space velocity carbon monoxide oxidation reaction. It can be seen that the catalyst still has a high reaction activity under high space velocity conditions.

[0064] Example 7

[0065] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0066] (2) 50 mg of the silver-containing precursor mixture obtained in step (1) was placed in a micro-vertical fixed-bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0067] (3) After cooling to room temperature, adjust the mass space velocity to 1200000 and 5600000 mL / g cath, and then the temperature was raised to 300 °C at a rate of 1 °C / min and maintained for 30 h. The reactants and products were analyzed online by Agilent GC490 chromatography to monitor the changes in CO conversion.

[0068] Figure 7 The Ag / SiO2 with an activated Ag loading of 5% described in Example 7 is 2 The stability of the catalyst for high-space-velocity carbon monoxide oxidation reaction. It can be seen that under the harsh conditions of ultra-high space velocity, the catalyst has excellent stability at high temperature.

[0069] Example 8

[0070] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0071] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0072] (3) After cooling to room temperature, 1% CO / 20% O 2 / 10%CO 2 / 100ppmC 3 H 6 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 500°C at a rate of 1°C / min. The reactants and products were analyzed online by Agilent GC490 chromatography to monitor the changes in CO conversion.

[0073] Figure 8 The Ag / SiO2 with an activated Ag loading of 5% as described in Example 8 is 2 Catalysts for CO 2 and C 3 H 6 The activity of carbon monoxide oxidation reaction in the atmosphere. 2 and C 3 H 6In the reaction atmosphere, the catalyst can efficiently convert CO and no deactivation is observed after long-term operation.

[0074] Example 9

[0075] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0076] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0077] (3) After cooling to room temperature, 1% CO / 20% O was introduced 2 / 10%CO 2 / 100ppmC 3 H 6 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 500°C at a rate of 1°C / min and maintained for 20 h. The reactants and products were analyzed online by Agilent GC490 chromatography to monitor the changes in CO conversion.

[0078] Figure 8 The Ag / SiO2 with an activated Ag loading of 5% described in Example 9 is 2 Catalysts for CO 2 and C 3 H 6 The stability of the carbon monoxide oxidation reaction. It can be seen that in the presence of CO 2 and C 3 H 6 In the reaction atmosphere, the catalyst operates stably at high temperature without deactivation.

[0079] Example 10

[0080] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO2 mixture;

[0081] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0082] (3) After cooling to room temperature, 1% CO / 20% O was introduced 2 / 10%CO 2 / 100ppmC 3 H 6 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 80°C at a rate of 1°C / min and maintained at 80°C for 20 h. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0083] Figure 8 The Ag / SiO2 with an activated Ag loading of 5% as described in Example 10 2 Catalysts for CO 2 and C 3 H 6 The stability of the carbon monoxide oxidation reaction. It can be seen that in the presence of CO 2 and C 3 H 6 In the reaction atmosphere, the catalyst operated stably without any deactivation.

[0084] Embodiment 11

[0085] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0086] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0087] (3) After cooling to room temperature, simulated automobile exhaust gas (1% CO / 20% O) was introduced. 2 / 5%H 2 O / 10% CO 2 / 100ppmC 3 H 6 / N 2 balance reaction gas), and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 500°C at a rate of 1°C / min. The reactants and products were analyzed online by Agilent GC490 chromatography to monitor the changes in CO conversion.

[0088] Fig. 9 The Ag / SiO2 with an activated Ag loading of 5% described in Example 11 is 2 The activity of the catalyst for automobile exhaust purification. It can be seen that even in the presence of high concentrations of CO 2 and H 2 O, the catalyst can completely convert CO at a relatively high temperature (200-500°C, the exhaust temperature range when the automobile engine is running), and still has a high catalytic activity at low temperatures. This shows that the Ag / SiO prepared by the method of the present invention 2 The catalyst can be used to eliminate automobile exhaust.

[0089] Example 12

[0090] (1) 0.2685 g Ag 2 O powder and 5g SiO calcined at 500℃ 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0091] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0092] (3) After cooling to room temperature, simulated automobile exhaust gas (1% CO / 20% O) was introduced. 2 / 5%H 2 O / 10% CO 2 / 100ppmC 3 H6 / N 2 balance reaction gas), and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 500°C at a rate of 1°C / min and maintained for 20 h. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0093] Fig. 9 The Ag / SiO2 with an activated Ag loading of 5% as described in Example 12 2 The stability of the catalyst used for automobile exhaust purification. It can be seen that even in the presence of high concentrations of CO 2 and H 2 O under the harsh conditions, the catalyst has high stability at high temperature. This shows that the Ag / SiO prepared by the method of the present invention 2 Catalysts have the potential to be used in automobile exhaust removal.

[0094] Example 13

[0095] (1) 0.2685 g Ag 2 O powder and 5g SiO 2 The powder mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 mixture;

[0096] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0097] (3) After cooling to room temperature, 150ppm HCHO / 20% O 2 / N 2 balance, adjust the flow rate to 36000mL / g cat h, and then the temperature was raised to 120°C at a rate of 1°C / min. The generated products were analyzed online using a GC-7800Ⅱ chromatograph to monitor the changes in HCHO conversion rate.

[0098] Fig.10 The Ag / SiO2 with an activated Ag loading of 5% described in Example 13 is 2 The activity of the catalyst for formaldehyde removal. It can be seen that the catalyst can effectively remove formaldehyde at low temperatures. This shows that the Ag / SiO prepared by the method of the present invention2 The catalyst has the potential to be used for the elimination of gaseous organic matter.

[0099] Comparative Example 1

[0100] (1) 0.2685 g Ag 2 O powder and 5g Al 2 O 3 The powder mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-Al 2 O 3 mixture;

[0101] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0102] (3) After cooling to room temperature, 1% CO / 20% O 2 / N 2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, and then the temperature was raised to 800°C at a rate of 1°C / min. The reactants and products were analyzed online by Agilent GC490 chromatography to monitor the changes in CO conversion.

[0103] Fig.11 The Ag / Al2O3 with an activated Ag loading of 5% described in Comparative Example 1 is 2 O 3 The activity of the catalyst for the carbon monoxide oxidation reaction. It can be seen that the catalyst has low activity at low temperatures, but has good resistance to sintering at high temperatures.

[0104] Comparative Example 2

[0105] (1) 0.2685 g Ag 2 O powder and 5g uncalcined SiO 2 The mixture was placed in an agate mortar and ground thoroughly for 0.5 h to obtain the silver-containing precursor Ag. 2 O-SiO 2 -pri mixture;

[0106] (2) 50 mg of the silver precursor mixture obtained in step (1) was placed in a micro vertical fixed bed quartz tube reactor and introduced into a 1% CO / 20% O 2 / N2 Balance the reaction gas and adjust the mass space velocity to 12000mL / g cat h, control the heating rate to be 1℃ / min and heat to 500℃ and keep it for 2h;

[0107] (3) After cooling to room temperature, the temperature was raised to 500°C at a rate of 1°C / min. The reactants and products were analyzed online using an Agilent GC490 chromatograph to monitor changes in CO conversion.

[0108] Fig.12 The 5% Ag / SiO 2 The catalytic activity of the -pri catalyst before and after activation. The sample was deactivated at high temperature, which indicates that the Ag particles in the sample sintered and grew in the high temperature reaction atmosphere.

[0109] In summary, the beneficial effects of the present invention are as follows: the catalyst of the present invention utilizes oxygen-rich reaction atmosphere to induce activation to prepare a Ag catalyst supported on silica or alumina, which improves the shortcomings of the previous impregnation method, which has complicated synthesis and processing steps, and the method is simple and easy to implement. The supported active Ag clusters have high stability under reaction conditions, which effectively improves the disadvantage of Ag-based catalysts being easy to sinter in carbon monoxide oxidation reactions, and at the same time achieves complete conversion of CO in a wide temperature range, and has great application potential in tail gas treatment (automobile and blast furnace tail gas purification).

Claims

1. A method for preparing a catalyst for carbon monoxide oxidation reaction, characterized in that: The oxidation reaction atmosphere is used to induce in situ the generation of highly dispersed active components, wherein the catalyst uses silicon dioxide as a carrier and metal Ag as an active component; The method comprises the following steps: (1) calcining the support at 450-550° C. for 5 h; (2) mechanically mixing the silver-containing solid precursor with the calcined carrier and grinding them thoroughly to obtain a mixture of the silver-containing precursor and the carrier; (2) calcining the mixture obtained in step (2) at 300-500° C. for 2-10 h in an oxygen-rich atmosphere to obtain an Ag / SiO2 catalyst; The oxygen-rich atmosphere is at least one of pure O2, O2 of different concentrations diluted by an inert gas, and a reaction gas with a volume ratio of O2 to CO ≥1.

2. The preparation method according to claim 1, characterized in that: The silver-containing solid precursor is silver powder or silver oxide powder; the particle size of the powder is 1nm-1μm.

3. An application of a catalyst prepared by the preparation method according to any one of claims 1 to 2, characterized in that: The catalyst is used for carbon monoxide oxidation reaction, oxidation elimination of gaseous organic matter, and purification of automobile / blast furnace tail gas.

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