CN113751024A

CN113751024A - Catalyst for catalytic oxidation of CO and preparation method thereof

Info

Publication number: CN113751024A
Application number: CN202111200523.7A
Authority: CN
Inventors: 李坚; 蔡建宇; 樊星; 于泽辉; 赵靖强
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2021-12-07
Anticipated expiration: 2041-10-14
Also published as: CN113751024B

Abstract

A catalyst for catalytic oxidation of CO and a preparation method thereof, belonging to the field of environmental engineering. The catalyst containing active components and auxiliaries is prepared by adopting an organic combination mode of an impregnation method, a precipitation method and a ball milling method, and the catalyst is prepared from two intermediates according to different proportions, wherein the intermediate I contains 0.1-12 wt% of precious metal active components, 86-99.8 wt% of non-precious metal oxides and 0.1-2 wt% of auxiliaries; the content of non-noble metal oxide active components in the intermediate II is 85-99.7 wt%, the content of the auxiliary agent is 0.3-15 wt%, the mixing mass ratio of the intermediate I and the intermediate II is 1: 9-9: 1, and the mixing ratio is adjusted to ensure that the content of noble metal active components in the catalyst is 0.09-1.2 wt%. Has good CO catalytic performance and sulfur-resistant and water-resistant performance.

Description

Catalyst for catalytic oxidation of CO and preparation method thereof

Technical Field

The invention relates to a catalyst for catalytic oxidation of CO and a preparation method thereof, which can be used for removing CO in tail gases of sintering, coking, boilers and the like, simultaneously recovering reaction heat and realizing efficient utilization of resources, and belongs to the field of environmental engineering.

Background

CO is one of the most main gaseous pollutants, has great harm, has the hidden danger of flammability and explosiveness, and can directly cause suffocation death of a human body. Catalytic oxidation technology, one of the methods for effectively removing CO, has been widely studied. At present, the research on the CO catalyst mainly focuses on reducing the ignition temperature of the CO catalyst, improving the stability of the CO catalyst, prolonging the service life of the catalyst and reducing the cost of the catalyst.

CN111437814A discloses a tin-doped platinum titanium catalyst, a preparation method and an application thereof, the tin-doped platinum titanium catalyst is synthesized by a coprecipitation method and an impregnation method, the catalyst gives full play to strong interaction among three components, the CO oxidation performance and the sulfur and water resistance of the catalyst are effectively improved, and CO discharged by a plant fixed source and a vehicle moving source can be effectively removed. CN103480369A discloses a platinum nano-composite catalyst, its preparation and application, the invention uses SiO₂The small ball is used as a carrier to load Pt nano particles to form SiO₂Pt core structure, wrapping a layer of mesoporous ZrO outside the core structure₂Formation of SiO₂/Pt/ZrO₂The catalyst is in a core-shell structure, is used for CO catalytic oxidation reaction, is circulated for 20 times, and has basically unchanged activity. CN107456965B discloses a supported palladium catalyst with cerium oxide as a carrier and a preparation method thereof, the invention obtains cerium oxide colloid and palladium solution through mixing and reacting solid alkali and metal salt, and the obtained cerium oxide colloid and palladium solution are subjected to uniform stirring, reaction loading, centrifugal washing, freeze drying, high-temperature roasting and low-temperature reduction to obtain the final catalyst. The catalyst has good low-temperature activity, and can realize complete conversion of CO at 60 ℃. CN103990470A discloses a supported iridium catalyst for carbon monoxide oxidation reaction and a preparation method thereof, wherein Al is used in the invention₂O₃As a carrier, an active component Ir is loaded on Al by an impregnation method₂O₃And one or more of the additives Fe, Co, Ni and Cu are added on the carrier. The prepared supported Ir catalyst has higher CO oxidation activity and stability.

At present, the existing CO catalyst is not successfully applied in practical engineering, and the research on the catalyst suitable for practical working conditions is the key for promoting the technical application of the CO catalyst.

Disclosure of Invention

Aiming at the problems of research and application of the current CO catalyst, the invention provides the catalyst for catalyzing and oxidizing CO and the preparation method thereof by combining the characteristics of the steel industry, especially sintering flue gas.

The technical scheme of the invention is as follows:

the catalyst containing active components and auxiliaries is prepared by organically combining an impregnation method, a precipitation method and a ball milling method, wherein the active components are noble metals and non-noble metals. The catalyst is prepared from two intermediates according to different proportions, wherein the intermediate I contains 0.1-12 wt% of noble metal active component, 86-99.8 wt% of non-noble metal oxide and 0.1-2 wt% of auxiliary agent; the content of non-noble metal oxide active components in the intermediate II is 85-99.7 wt%, the content of the auxiliary agent is 0.3-15 wt%, the mixing mass ratio of the intermediate I and the intermediate II is 1: 9-9: 1, and the mixing ratio is further adjusted according to the content of noble metal active components in the intermediate I to ensure that the content of noble metal active components in the catalyst is 0.09-1.2 wt%.

Wherein the noble metal active component in the intermediate I is one or two or more metals, oxides or combination thereof of Pt, Ag, Pd, Rh, Ir, Ru, Os or Au, and the non-noble metal oxide is TiO₂、MnO₂、FeO_x、CuO、CeO₂Or one or two or more of ZrO, and the assistant is one or two or more of Co, Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb, V, etc., and oxygenCompounds or combinations thereof, and non-noble metal oxides and promoters are different. The non-noble metal active component in the intermediate II is Co₃O₄The auxiliary agent is one or two or more of Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb and V, or the combination thereof.

A method of preparing a catalyst for the catalytic oxidation of CO, comprising the steps of:

(1) weighing corresponding precious metal precursors (acid or salt of Pt, Ag, Pd, Rh, Ir, Ru, Os or Au), non-precious metal oxides and auxiliary agent precursors (acid, alkali or salt of Co, Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb and V) according to the components of the intermediate I;

(2) preparing a catalyst intermediate I by using an impregnation method; placing a mixture formed by uniformly mixing a noble metal precursor, a non-noble metal oxide and an auxiliary agent precursor in deionized water in an ultrasonic cleaning instrument, ultrasonically stirring for 1-6 hours in a water bath at 50-80 ℃, and then drying to obtain a mixture; roasting the mixture in a muffle furnace at the temperature of 300-600 ℃ for 1-6 hours, and cooling to obtain a catalyst intermediate I;

(3) weighing corresponding non-noble metal active component Co according to the intermediate II component₃O₄Precursor (Co-containing soluble salt such as cobalt nitrate and cobalt acetate), auxiliary precursor (acid, alkali or salt containing Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb and V), and deionized water₃O₄Dissolving the precursor and part of the auxiliary agent precursor (soluble and can generate insoluble precipitate under the alkaline condition) to form a solution, heating the solution to 60-80 ℃ in a water bath under ultrasonic stirring, and then slowly dropwise adding Na into the solution₂CO₃、NaOH、NH₃H₂O，(NH₄)₂CO₃、NH₄HCO₃、K₂CO₃One or more than two of alkali liquors such as KHCO3, and the like until the pH value is 8-14, and stopping dripping the alkali liquor; ultrasonically stirring the obtained suspension in a water bath at the temperature of 60-80 ℃ for 1-6 hours to form suspension;

(4) if insoluble or precursor incapable of generating precipitate under alkaline condition exists in the auxiliary agent precursor of the intermediate II, adding the auxiliary agent precursor step by step, stirring the suspension obtained in the step (3), washing to be neutral, adding water again, stirring uniformly, adding the rest auxiliary agent precursor (insoluble or precursor incapable of generating precipitate under alkaline condition) obtained in the step (3), and ultrasonically stirring in water bath at 60-80 ℃ for 1-6 hours; drying the obtained mixture, roasting for 2-6 hours at the temperature of 350-450 ℃, and cooling to obtain a catalyst intermediate II;

if the precursor of the auxiliary agent of the intermediate II does not have insolubility or can not generate a precursor of a precipitate under an alkaline condition, directly stirring the suspension liquid in the step (3), washing to be neutral, fully drying the paste, roasting for 2-6 hours at 350-450 ℃, and cooling to obtain a catalyst intermediate II;

(5) adding water into the intermediate I and the intermediate II obtained in the steps (2) and (4) according to a mass ratio of (1: 9-9: 1), uniformly mixing, and adding into a ball milling tank; the ball milling tank filled with the mixture and the grinding balls is arranged in a ball mill, and is rotated forwards for 20min to 40min under the rotating speed condition of 200r/min to 450r/min and is rotated backwards for 30min to 40min under the rotating speed condition of 450r/min to 600 r/min; after the ball milling is finished, taking out the catalyst slurry and drying; roasting the mixture for 2 to 6 hours in a muffle furnace at the temperature of 350 to 450 ℃ in air atmosphere, and cooling the mixture to obtain CO catalyst powder.

The invention has the following advantages:

1. the invention has good CO catalytic performance, greatly reduces the consumption of noble metal, and can realize the complete conversion of CO at about 120 ℃.

2. The invention has good sulfur-resistant and water-resistant performance, is easy to regenerate, and greatly prolongs the service life of the catalyst.

3. The catalyst has simple preparation process and is easy for large-scale production and market popularization and application.

Drawings

FIG. 1 is a graph of the CO catalytic performance of catalyst # 1 obtained in example 1.

FIG. 2 is a graph showing the sulfur resistance and water resistance of the catalyst # 1 obtained in example 1.

Fig. 3 is a graph of the CO catalytic performance of the # 2 catalyst obtained in example 2.

FIG. 4 is a graph of the sulfur resistance versus water resistance of the catalyst # 2 obtained in example 2.

Detailed Description

Example 1:

weighing 28g of titanium dioxide in a beaker, adding 0.3g of chloroplatinic acid and 0.2g of cerium nitrate, adding deionized water, uniformly mixing, putting into an ultrasonic cleaning instrument, ultrasonically stirring for 4 hours in a water bath at 75 ℃, drying in a drying oven at 110 ℃, and roasting the dried catalyst in a muffle furnace at 460 ℃ for 3 hours. And naturally cooling to obtain the catalyst intermediate I. Weighing 24g of cobalt acetate, 1.2g of stannous chloride and 0.05g of ammonium molybdate, dissolving the cobalt acetate, the stannous chloride and the ammonium molybdate in deionized water, placing the solution in an ultrasonic cleaning instrument, ultrasonically stirring the solution in a water bath at the temperature of 75 ℃ for 0.5 hour, dropwise adding a sodium carbonate solution until the pH value of the solution is about 10, and stopping dropwise adding the sodium carbonate solution. After stirring for 4 hours, the suspension was washed to neutrality (pH 7), the resulting paste was dried in an oven at 110 ℃, and the dried catalyst was calcined in a muffle furnace at 400 ℃ for 4 hours. And naturally cooling to obtain a catalyst intermediate II. Mixing the catalyst intermediate I and the catalyst intermediate II according to the proportion of 1:1, placing the mixture into a ball milling tank, performing ball milling clockwise for 20min by using a planetary ball mill at the rotating speed of 300r/min, then increasing the rotating speed to 480r/min, performing ball milling counterclockwise for 40min, taking out catalyst slurry after the ball milling is finished, drying the slurry, and roasting the slurry in a muffle furnace at the temperature of 400 ℃ for 3 h. And after the catalyst is cooled to room temperature, drying, sealing and storing for later use, and marking as No. 1.

Example 2:

weighing 22g of titanium dioxide in a beaker, adding 0.3g of chloroplatinic acid and 0.1g of ammonium tungstate, adding deionized water, uniformly mixing, putting into an ultrasonic cleaning instrument, ultrasonically stirring for 4 hours in a water bath at 75 ℃, drying in a drying oven at 110 ℃, and roasting the dried catalyst for 3 hours at 450 ℃ in a muffle furnace. And naturally cooling to obtain the catalyst intermediate I. Weighing 12g of cobalt acetate and 0.62g of cerium nitrate, dissolving in deionized water, placing the solution in an ultrasonic cleaning instrument, ultrasonically stirring in a water bath at 75 ℃ for 0.5 hour, dropwise adding a sodium carbonate solution until the pH value of the solution is about 10, and stoppingThe dropping of the sodium carbonate solution is stopped. After stirring for a further 4 hours, the suspension is washed to neutrality (pH 7), the paste is subsequently redissolved in water and 0.02g of γ -Fe are added₂O₃Then, the mixture is ultrasonically stirred for 3 hours in a water bath at 70 ℃, the obtained paste is dried in an oven at 110 ℃, and the dried catalyst is roasted for 4 hours at 400 ℃ in a muffle furnace. And naturally cooling to obtain a catalyst intermediate II. Mixing the catalyst intermediate I and the catalyst intermediate II according to the proportion of 1:1, placing the mixture into a ball milling tank, performing ball milling clockwise for 20min by using a planetary ball mill at the rotating speed of 200r/min, then increasing the rotating speed to 500r/min, performing ball milling counterclockwise for 40min, taking out catalyst slurry after the ball milling is finished, drying the slurry, and roasting the slurry in a muffle furnace at 390 ℃ for 3.5 h. And after the catalyst is cooled to room temperature, drying, sealing and storing for later use, and marking as # 2.

Test example 1:

taking the catalyst # 1 in example 1 as an example, a CO catalysis experiment was performed to test the CO catalysis performance and the sulfur-resistant and water-resistant performance. Testing the components of the smoke: the CO content is 8000ppm, O₂Content 16%, N₂As balance gas, the space velocity is 30000h^-1The CO catalytic efficiency is plotted against temperature in fig. 1. When the temperature of the flue gas reaches more than 120 ℃, the catalytic effect can reach more than 99 percent; the experimental conditions of sulfur and water introduction are as follows: the CO content is 8000ppm, O₂16% of SO₂Content 50ppm, H₂O content of 15%, N₂As balance gas, the space velocity is 30000h^-1The CO catalytic efficiency curve with time is shown in FIG. 2, wherein the test temperature is 230 ℃ for the first 64h, and the temperature is increased to 235 ℃ after 64 h. The catalyst has good sulfur-resistant and water-resistant effects, and can achieve a catalytic effect of over 85% in 100h under the condition of sulfur and water.

Test example 2:

taking the 2# catalyst in example 2 as an example, a CO catalysis experiment was performed to test the CO catalysis performance and the sulfur-resistant and water-resistant performance. Testing the components of the smoke: the CO content is 8000ppm, O₂16% of SO₂Content 50ppm, H₂O content of 15%, N₂As balance gas, the space velocity is 30000h^-1CO catalysisThe curve of the conversion efficiency with temperature is shown in fig. 1. When the temperature of the flue gas reaches more than 110 ℃, the catalytic effect can reach 100 percent; 50ppm of SO was introduced at 280 deg.C₂And 15% of H₂The curve of the change of the catalytic efficiency of O and CO with time is shown in figure 2, the catalyst has good sulfur-resistant and water-resistant effects, and can achieve a catalytic effect of over 99% within 175h without obvious attenuation under the condition of sulfur and water.

Claims

1. The catalyst for catalytic oxidation of CO is characterized by comprising an active component and an auxiliary agent, wherein the active component is a noble metal or a non-noble metal; the catalyst is prepared from two intermediates according to different proportions, wherein the intermediate I contains 0.1-12 wt% of noble metal active component, 86-99.8 wt% of non-noble metal oxide and 0.1-2 wt% of auxiliary agent; the content of non-noble metal oxide active components in the intermediate II is 85-99.7 wt%, the content of the auxiliary agent is 0.3-15 wt%, and the mixing mass ratio of the intermediate I to the intermediate II is 1: 9-9: 1.

2. The catalyst for catalytic oxidation of CO according to claim 1, wherein the mixing ratio is adjusted according to the content of the noble metal active component in the intermediate I to ensure that the content of the noble metal active component in the catalyst is 0.09-1.2 wt%.

3. The catalyst of claim 1, wherein the noble metal active component in the intermediate I is one or two or more metals, oxides or combinations thereof selected from Pt, Ag, Pd, Rh, Ir, Ru, Os or Au, and the non-noble metal oxide is TiO₂、MnO₂、FeO_x、CuO、CeO₂Or one or two or more of ZrO, the auxiliary agent is one or two or more of Co, Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb, V and the like, oxides or combinations thereof, and the non-noble metal oxides and the auxiliary agent are different. The non-noble metal active component in the intermediate II is Co₃O₄The auxiliary agent is Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb and VOne or two or more kinds of metals, oxides or combinations thereof.

4. A process for preparing the catalyst of any one of claims 1 to 3, comprising the steps of:

(3) weighing corresponding non-noble metal active component Co according to the intermediate II component₃O₄Precursor (Co-containing soluble salt such as cobalt nitrate and cobalt acetate), auxiliary precursor (acid, alkali or salt containing Cr, Zr, Sn, Mo, W, Fe, Ce, Ni, Nb and V), and deionized water₃O₄Dissolving the precursor and part of the auxiliary agent precursor to form a solution, heating the solution to 60-80 ℃ in a water bath under ultrasonic stirring, and then slowly dropwise adding Na into the solution₂CO₃、NaOH、NH₃H₂O，(NH₄)₂CO₃、NH₄HCO₃、K₂CO₃One or more than two of alkali liquors such as KHCO3, and the like until the pH value is 8-14, and stopping dripping the alkali liquor; ultrasonically stirring the obtained suspension in a water bath at the temperature of 60-80 ℃ for 1-6 hours to form suspension;

(4) if insoluble or a precursor incapable of generating precipitate under an alkaline condition exists in the auxiliary agent precursor of the intermediate II, adding the precursor step by step, stirring the suspension obtained in the step (3), washing to be neutral, adding water again, stirring uniformly, adding the rest auxiliary agent precursor obtained in the step (3), and ultrasonically stirring in a water bath at the temperature of 60-80 ℃ for 1-6 hours; drying the obtained mixture, roasting for 2-6 hours at the temperature of 350-450 ℃, and cooling to obtain a catalyst intermediate II;