A honeycomb catalyst for removing CO component of low-temperature sintering flue gas and a preparation method thereof

Abstract

The application relates to a honeycomb catalyst for removing CO components of low-temperature sintering flue gas and a preparation method thereof. The catalyst carrier is prepared by mixing TiO2 and Fe-SAPO-34, Ag is coated on the carrier as an active component, Co3O4 and Ce2(SO4)3 are used as active aids, and the honeycomb CO removal catalyst is prepared by an extrusion molding method. The preparation method is simple, the steps are easy to operate, the prepared catalyst has the advantages of high adsorption capacity, high low-temperature catalytic oxidation CO activity, good water and sulfur resistance and good mechanical property, can be used for removing CO components of low-temperature sintering flue gas in the steel industry, and the CO removal rate can reach more than 90% under the condition of 120-180 DEG C flue gas, and the industrial application value is better.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a honeycomb catalyst for removing CO components in low-temperature sintering flue gas and a preparation method thereof. BACKGROUND

[0002] At present, the energy supply in China is still mainly fossil fuels, and the use of fossil fuels will inevitably cause air pollution problems. In addition to the serious harm of PM2.5, SO2, NOx and other pollutants, the influence of CO gas on the human living environment cannot be ignored. When the concentration of CO in the air reaches 100 ppm, it will cause human discomfort, and higher concentration of CO will directly affect the human central nervous system and internal organs, causing great harm to life and health.

[0003] In the steel industry, especially in the sintering process, the local oxygen deficiency and carbon gasification reaction of the sintering material layer is the main reason for the generation of CO. The CO concentration in the sintering flue gas can reach 5000 mg / Nm 3 The above emission even exceeds the total amount of SO2 and NOx. Therefore, the removal of CO in sintering flue gas has become a key problem in the steel industry. At present, the removal methods of CO mainly include adsorption method and catalytic method. The adsorption method is to adsorb CO components from flue gas by special materials. When the adsorption material reaches saturation, CO is desorbed and purified for the synthesis of acid, alcohol, aldehyde, ether and other products, but the adsorption capacity is small, the selectivity is low, the desorption is difficult, and the CO purity after desorption is low. The problems such as adsorption capacity, selectivity, desorption difficulty and low CO purity after desorption have always been the difficulties of adsorption method. The catalytic method is to make CO in flue gas react with O2 to generate CO2 through the action of catalyst. Compared with the adsorption method, the catalytic method has significant advantages in operation cost and removal effect, and is considered to be the most popular CO removal technology. Therefore, the development of CO oxidation catalyst with high low-temperature activity, sulfur resistance and water resistance for 120-180℃ low-temperature flue gas in the sintering process of the steel industry is the key technology. SUMMARY

[0004] The application is to solve the problems of poor water resistance, poor sulfur resistance and poor use effect in industrial flue gas treatment of the existing CO oxidation catalyst, and provides a honeycomb catalyst for removing CO components in low-temperature sintering flue gas and a preparation method thereof.

[0005] The application adopts the following technical scheme: A honeycomb catalyst for removing CO components in low-temperature sintering flue gas, wherein the catalyst carrier is composed of TiO2, Fe2O3 and SAPO-34, the catalyst active component is Ag, accounting for 0.2-0.5% of the total mass of the catalyst, the active additive is Co3O4, accounting for 3-6% of the total mass of the catalyst, the active additive Ce2(SO4)3 accounts for 2-4% of the total mass of the catalyst, the mass of the catalyst carrier accounts for 89.5-94.8% of the total mass of the catalyst, TiO2 accounts for 75-85% of the mass of the catalyst carrier, Fe2O3 accounts for 3-5% of the mass of the catalyst carrier, and SAPO-34 accounts for 12-20% of the mass of the catalyst carrier.

[0006] Further, the TiO2 is anatase type.

[0007] Further, the inner wall thickness of the honeycomb catalyst is 0.9-1.1 mm, and the outer wall thickness is 1.2-1.4 mm.

[0008] A preparation method of a honeycomb catalyst for removing CO components in low-temperature sintering flue gas, comprising the following steps:

[0009] S1 carrier preparation:

[0010] Iron nitrate nonahydrate and trimethylolpropane are weighed according to a molar ratio of 10:1 and dissolved with an appropriate amount of deionized water, and after the solid is completely dissolved, the solution is heated to 75-85 DEG C by microwave heating, dimethylol ethylene glycol acrylate is added to the solution, the mass of dimethylol ethylene glycol acrylate is 0.5-1.5% of the mass of iron nitrate nonahydrate, the solution is naturally cooled to room temperature after heating for 20 min, the above solution is added to SAPO-34, stirred uniformly and then calcined at 450 DEG C for 2-4 h to obtain Fe2O3-SAPO-34 powder, and the powder is uniformly mixed with TiO2 to obtain a catalyst mixed carrier;

[0011] S2 catalyst mud preparation:

[0012] A mixed aqueous solution of silver nitrate, cobalt nitrate and cerium sulfate is prepared according to the proportion, the solution is added to the mixed carrier prepared in S1, stirring is carried out for 1-1.5 h, 12-20% of the mass of the carrier is added as a forming aid, the honeycomb catalyst mud is obtained after the forming aid is stirred uniformly, and the mud is aged at room temperature for 20-24 h;

[0013] S3 honeycomb catalyst preparation:

[0014] After the mud is filtered, the honeycomb catalyst embryo is obtained by extrusion molding, the embryo with a water content of less than 5% is obtained after grading drying, and the honeycomb catalyst is obtained after gradual temperature calcination.

[0015] Further, the green body is sequentially dried at 25℃ for 72 h, 40℃ for 48 h, 50℃ for 48 h, 60℃ for 24 h and 80℃ for 12 h.

[0016] Further, the green body is baked according to a temperature rising procedure of rising to 120℃ for 2 h, keeping at 120℃ for 2 h, rising to 280℃ for 3 h, keeping at 280℃ for 3 h, rising to 450℃ for 5 h and keeping at 450℃ for 5 h.

[0017] Further, the forming aid comprises, by mass percentage, 30% montmorillonite, 20% white carbon black, 30% 9mm glass fiber, 7.5% carboxymethyl cellulose, 7.5% polyvinyl alcohol and 5% stearic acid.

[0018] The advantages of the present application are as follows:

[0019] (1) The catalyst prepared by the present application has high activity in the low-temperature sintering flue gas temperature range. The addition of Fe2O3 component in the preparation process of the carrier can increase the amount of active oxygen on the surface of SAPO-34 and reduce the grain size, and after calcination, 10-20 nm Fe2O3-SAPO-34 particles with high specific surface area and high porosity are obtained. Mixing TiO2 commonly used in industrial catalysts as a carrier can make the catalyst have strong CO adsorption and activation capacity. Ag is a common active component of noble metal type catalysts, and when used with a mixed carrier without adding active additives, the CO removal rate can reach 70-75%, and after adding active additives Ce2(SO4)3 and Co3O4, the CO removal rate can be increased to more than 90%. This is not only because Ce ions have excellent oxygen storage performance, but more importantly, Ce 3+ and Ce 4+ can interact with Fe2O3 in the carrier, further improving the oxygen storage and oxygen flow capacity of the catalyst surface and the CO oxidation performance. In addition, through the influence of Fe2O3 action, calcination and other conditions, the exposed crystal face of Co in the catalyst is mainly (111) face, and (111) face is in a highly unsaturated state, with a large number of exposed active oxygen, further improving the CO catalytic oxidation activity of the catalyst.

[0020] (2) The catalyst has good water resistance. The molecular sieve component has poor water resistance and is prone to structural collapse when used in industrial flue gas. In the present application, TiO2 is used as the main component of the carrier, and the molecular sieve accounts for only 12-20%, and the SAPO-34 molecular sieve has relatively good hydrothermal stability. In the preparation of Fe2O3-SAPO-34, the addition of trimethylolpropane and dimethyl acrylate ethylene glycol can cross-link the Fe 3+The stronger chemical bond between SAPO-34 is formed, a reticular framework structure is formed, stronger support is provided, and the structure collapse of SAPO-34 in use is avoided, and the service life of the catalyst is affected.

[0021] (3) The catalyst has good sulfur resistance, the component which is not easy to react with SO2 and SO3 is used as the active component and the active adjuvant, and through the interaction of the active adjuvant and the carrier, the Fe2O3 component in the carrier can be protected from being sulfidized, that is, the CO catalytic oxidation performance of the catalyst is ensured, and at the same time, the catalyst can be stably operated in the sulfur-containing flue gas.

[0022] (4) The catalyst has strong mechanical strength. After being formed by the extrusion molding process, the catalyst has strong compressive strength through the refinement drying and calcination, and the adjustment of the molding adjuvant, and can be stably used in the industrial flue gas. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The CO oxidation performance test results of the catalysts of Examples 1-4 and Comparative Examples are shown in the following figures. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be further described below in combination with specific embodiments. Example One

[0025] S1. Preparation of the carrier

[0026] Dissolve 4.04 kg of iron nitrate nonahydrate and 134 g of trimethylolpropane in 2.1 kg of deionized water, heat the solution to 75℃ by microwave heating after the solid is completely dissolved, then add 20.2 g of ethylene glycol dimethacrylate to the solution, keep heating for 20 min, then naturally cool the solution to room temperature, then add the solution to 3.2 kg of SAPO-34, stir uniformly, and then calcine at 450℃ for 2 h to obtain Fe2O3-SAPO-34 powder with an average particle size of 12 nm. Mix the powder with 12 kg of TiO2 to obtain 16 kg of Fe2O3-SAPO-34-TiO2 mixed carrier, and the content of the three components in the carrier is 5%, 20% and 75% respectively;

[0027] S2. Preparation of the catalyst mud

[0028] Take 34 g of silver nitrate, 1.84 kg of cobalt nitrate hexahydrate and 0.34 kg of cerium sulfate, dissolve with 9.6 kg of deionized water, then add the solution to the mixed carrier obtained in step 1, stir for 1 h, then add 0.96 kg of montmorillonite, 0.64 kg of white carbon black, 0.96 kg of 9 mm glass fiber, 0.24 kg of carboxymethyl cellulose, 0.24 kg of polyvinyl alcohol and 0.16 kg of stearic acid, stir uniformly to obtain a honeycomb catalyst paste, and then place the paste in a room temperature environment for 24 h;

[0029] S3. Preparation of honeycomb catalyst

[0030] The paste obtained in S2 is filtered, and then passed through an extrusion molding device and a special mold to obtain a 13-hole honeycomb catalyst body with an inner wall thickness of 0.9 mm, an outer wall thickness of 1.2 mm, and a cross-sectional size of 7.5x7.5 cm. The body is sequentially dried at 25°C for 72 h, 40°C for 48 h, 50°C for 48 h, 60°C for 24 h and 80°C for 12 h to obtain a body with a water content of less than 5%. Finally, the body is subjected to a temperature rising program of 2 h to 120°C, 2 h at 120°C, 3 h to 280°C, 3 h at 280°C, 5 h to 450°C, and 5 h at 450°C to complete the calcination, thereby obtaining a honeycomb catalyst.

[0031] The composition of the honeycomb CO oxidation catalyst prepared by the above steps includes: 0.2% Ag, 3% Co3O4, 2% Ce2(SO4)3, 94.8% Fe2O3-SAPO-34-TiO2. Example Two

[0032] S1. Preparation of carrier

[0033] Dissolve 2.85 kg of iron nitrate nonahydrate and 94.5 g of trimethylolpropane in 1.7 kg of deionized water. After the solids are completely dissolved, heat the solution to 85°C by microwave heating. Then add 42.75 g of ethylene glycol dimethacrylate to the solution, maintain heating for 20 min, and then naturally cool the solution to room temperature. Then add the solution to 2.26 kg of SAPO-34, stir uniformly, and then calcine at 450°C for 4 h to obtain Fe2O3-SAPO-34 powder. Mix the powder with 16 kg of TiO2 to obtain a Fe2O3-SAPO-34-TiO2 mixed carrier, and the contents of the three components in the carrier are 3%, 12% and 85%, respectively.

[0034] S2. Preparation of catalyst paste

[0035] Take 166 g of silver nitrate, 4.59 kg of cobalt nitrate hexahydrate and 0.84 kg of cerium sulfate, dissolve with 13.2 kg of deionized water, then add the solution to the mixed carrier obtained in step 1, stir for 1 h, then add 1.13 kg of montmorillonite, 0.75 kg of white carbon black, 1.13 kg of glass fiber, 0.28 kg of carboxymethyl cellulose, 0.28 kg of polyvinyl alcohol and 0.19 kg of stearic acid, and then stir until the molding aid is uniformly distributed to obtain a honeycomb catalyst paste, and then the paste is placed in a room temperature environment for 24 h;

[0036] S3. Preparation of honeycomb catalyst

[0037] The paste obtained in step 2 is filtered, then passed through an extrusion molding device and a special mold to obtain a 18-hole honeycomb catalyst body with an inner wall thickness of 1.1 mm, an outer wall thickness of 1.4 mm, and a cross-sectional size of 10x10 cm, and then the body is sequentially dried at 25°C for 72 h, 40°C for 48 h, 50°C for 48 h, 60°C for 24 h and 80°C for 12 h to obtain a body with a water content of less than 5%, and finally the body is subjected to a temperature rising program of 2 h to 120°C, 2 h at 120°C, 3 h to 280°C, 3 h at 280°C, 5 h to 450°C, and 5 h at 450°C to complete the calcination, thereby obtaining a honeycomb catalyst.

[0038] The composition of the honeycomb CO oxidation catalyst prepared by the above steps includes: 0.5% Ag, 6% Co3O4, 4% Ce2(SO4)3, 89.5% Fe2O3-SAPO-34-TiO2. Example Three

[0039] S1. Preparation of carrier

[0040] Dissolve 3.79 kg of iron nitrate nonahydrate and 93.8 g of trimethylolpropane in 2.1 kg of deionized water, then heat the solution to 80°C by microwave heating, then add 37.9 g of ethylene glycol dimethacrylate to the solution, maintain heating for 20 min, then naturally cool the solution to room temperature, then add the solution to 3 kg of SAPO-34, stir until uniform, then calcine at 450°C for 3 h to obtain Fe2O3-SAPO-34 powder, then mix the powder with 15 kg of TiO2 to obtain a Fe2O3-SAPO-34-TiO2 mixed carrier, and the content of the three components in the carrier is 4%, 16% and 80% respectively;

[0041] S2. Preparation of catalyst paste

[0042] Weigh 95.5 g of silver nitrate, 2.94 kg of cobalt nitrate hexahydrate and 0.61 kg of cerium sulfate, dissolve them in 12.2 kg of deionized water, and then add the solution to the mixed carrier obtained in step 1, and after stirring for 1 h, add 0.84 kg of montmorillonite, 0.56 kg of white carbon black, 0.84 kg of glass fiber, 0.21 kg of carboxymethyl cellulose, 0.21 kg of polyvinyl alcohol and 0.14 kg of stearic acid, and after the molding aids are uniformly stirred, a honeycomb catalyst paste is obtained, which is aged at room temperature for 24 h;

[0043] S3. Preparation of honeycomb catalyst

[0044] After the paste obtained in S2 is filtered, a 16-hole honeycomb catalyst body with an inner wall thickness of 1.0 mm, an outer wall thickness of 1.3 mm and a cross-sectional size of 10x10 cm is obtained through an extrusion molding device and a special mold, and the body is sequentially dried at 25°C for 72 h, 40°C for 48 h, 50°C for 48 h, 60°C for 24 h and 80°C for 12 h to obtain a body with a water content of less than 5%, and finally the body is subjected to a temperature rising program of 2 h to 120°C, 2 h at 120°C, 3 h to 280°C, 3 h at 280°C, 5 h to 450°C and 5 h at 450°C to complete calcination, thereby obtaining a honeycomb catalyst.

[0045] The composition of the honeycomb CO oxidation catalyst prepared by the above steps includes: 0.3% Ag, 4% Co3O4, 3% Ce2(SO4)3, 92.7% Fe2O3-SAPO-34-TiO2. Example Four

[0046] S1. Preparation of carrier

[0047] Dissolve 3.63 kg of iron nitrate nonahydrate and 120 g of trimethylolpropane in 2.2 kg of deionized water, and after the solids are completely dissolved, heat the solution to 80°C by microwave heating, then add 43.6 g of ethylene glycol dimethacrylate to the solution, maintain heating for 20 min, and then naturally cool the solution to room temperature, then add the solution to 3.23 kg of SAPO-34, stir uniformly, and then calcine at 450°C for 2.5 h to obtain Fe2O3-SAPO-34 powder, mix the powder with 14 kg of TiO2 to obtain a Fe2O3-SAPO-34-TiO2 mixed carrier, and the contents of the three components in the carrier are 4%, 18% and 78% respectively;

[0048] S2. Preparation of catalyst paste

[0049] Take 124 g of silver nitrate, 3.58 kg of cobalt nitrate hexahydrate and 0.69 kg of cerium sulfate, dissolve with 11.85 kg of deionized water, then add the solution to the mixed carrier obtained in step 1, stir for 1 h, then add 0.86 kg of montmorillonite, 0.57 kg of white carbon black, 0.86 kg of glass fiber, 0.22 kg of carboxymethyl cellulose, 0.22 kg of polyvinyl alcohol and 0.14 kg of stearic acid, and then obtain a honeycomb catalyst paste after the shaping aids are uniformly stirred. The paste is aged at room temperature for 24 h;

[0050] S3. Preparation of honeycomb catalyst

[0051] The paste obtained in step 2 is filtered, and then passed through an extrusion molding device and a special mold to obtain a 15-hole honeycomb catalyst body with an inner wall thickness of 0.95 mm, an outer wall thickness of 1.35 mm, and a cross-sectional size of 7.5x7.5 cm. The body is sequentially dried at 25°C for 72 h, 40°C for 48 h, 50°C for 48 h, 60°C for 24 h and 80°C for 12 h to obtain a body with a water content of less than 5%. Finally, the body is subjected to a temperature rising program of 2 h to 120°C, 2 h at 120°C, 3 h to 280°C, 3 h at 280°C, 5 h to 450°C, and 5 h at 450°C to complete the calcination, thereby obtaining a honeycomb catalyst.

[0052] The composition of the honeycomb CO oxidation catalyst prepared by the above steps includes: 0.4% Ag, 5% Co3O4, 3.5% Ce2(SO4)3, 91.1% Fe2O3-SAPO-34-TiO2.

[0053] Comparative example

[0054] A commercial honeycomb CO oxidation catalyst is purchased, which is coated with Pd and Mn as active ingredients on an active alumina honeycomb carrier, and has a size of 100 mm x 100 mm x 100 mm.

[0055] Detection: The honeycomb catalysts in the examples are tested for compressive strength and CO oxidation performance. The CO oxidation performance test conditions are: CO concentration of 2000 mg / m 3 , SO2 concentration of 1000 mg / m 3 , O2 concentration of 5%, H2O concentration of 8%, and space velocity of 15000 h -1 .

[0056] The compressive strength test results are shown in Table 1.

[0057] Table 1 Catalyst compressive strength results

[0058]

[0059] From Table 1, it can be seen that the axial and radial compressive strengths of the honeycomb catalysts prepared in Examples 1 to 4 are superior to those of the comparative example, i.e. the compressive strength of the honeycomb catalyst prepared according to the process provided in the application is superior to that of the commercial catalyst of the same type, meeting the requirements for industrial use.

[0060] Figure 1 The CO oxidation performance test results of the catalysts of the comparative example and Examples 1 to 4 are shown in the graph. Figure 1 It can be seen that the activity of the catalysts of Examples 1 to 4 in catalyzing the oxidation of CO is higher than that of the catalyst of the comparative example in the range of 120 to 180°C, i.e. the CO oxidation catalyst provided in the application has excellent activity and can be used for removing CO components in low-temperature sintering flue gas in the steel industry.

Claims

1. A honeycomb catalyst for removing CO components of low-temperature sintering flue gas, characterized by: The catalyst carrier is composed of TiO2, Fe2O3 and SAPO-34, the catalyst active component is Ag, accounting for 0.2-0.5% of the total mass of the catalyst, the active auxiliary agent is Co3O4, accounting for 3-6% of the total mass of the catalyst, the active auxiliary agent Ce2(SO4)3 accounts for 2-4% of the total mass of the catalyst, the mass of the catalyst carrier accounts for 89.5-94.8% of the total mass of the catalyst, TiO2 accounts for 75-85% of the mass of the catalyst carrier, Fe2O3 accounts for 3-5% of the mass of the catalyst carrier, and SAPO-34 accounts for 12-20% of the mass of the catalyst carrier.

2. The honeycomb catalyst for removing CO components of low-temperature sintering flue gas according to claim 1, characterized by: The TiO2 is anatase type.

3. The honeycomb catalyst for removing CO components of low-temperature sintering flue gas according to claim 1, characterized in that: The thickness of the inner wall of the honeycomb catalyst is 0.9-1.1 mm, and the thickness of the outer wall is 1.2-1.4 mm.

4. The method for preparing the honeycomb catalyst for removing the CO component of the low-temperature sintering flue gas according to claim 1, characterized in that: It comprises the following steps: S1 carrier preparation: Fe(NO3)3·9H2O and trimethylolpropane are weighed according to a molar ratio of 10:1 and dissolved with an appropriate amount of deionized water. After the solid is completely dissolved, the solution is heated to 75-85℃ by microwave heating. Dimethyl glycol acrylate is added to the solution, and the mass of dimethyl glycol acrylate is 0.5-1.5% of the mass of Fe(NO3)3·9H2O. After heating for 20-25 min, the solution is naturally cooled to room temperature. The above solution is added to SAPO-34, stirred uniformly, and then calcined at 450℃ for 2-4 h to obtain Fe2O3-SAPO-34 powder. The powder is mixed with TiO2 in proportion to obtain a catalyst mixed carrier; S2 catalyst mud preparation: A mixed aqueous solution of silver nitrate, cobalt nitrate and cerium sulfate is prepared in proportion, and the solution is added to the mixed carrier prepared in S1. After stirring for 1-1.5 h, 12-20% of the mass of the carrier is added as a molding aid. After the molding aid is stirred uniformly, a honeycomb catalyst mud is obtained. The mud is aged at room temperature for 20-24 h. S3 honeycomb catalyst preparation: After the mud is filtered, the honeycomb catalyst embryo is obtained by extrusion molding. After grading drying, the embryo with a water content of less than 5% is obtained. The embryo is gradually calcined at a gradually increasing temperature to obtain a honeycomb catalyst.

5. The method for preparing the honeycomb catalyst for removing the CO component of the low-temperature sintering flue gas according to claim 4, characterized in that: The embryo is sequentially dried at 25℃ for 72 h, 40℃ for 48 h, 50℃ for 48 h, 60℃ for 24 h and 80℃ for 12 h.

6. The method of claim 4, wherein the method further comprises: The embryo is calcined according to the following temperature rising program: 2 h to 120℃, 120℃ for 2 h, 3 h to 280℃, 280℃ for 3 h, 5 h to 450℃, and 450℃ for 5 h. ​ 7. The method of claim 4, wherein the method further comprises: The components in the molding aid are as follows in terms of mass percentage: 30% montmorillonite, 20% white carbon black, 30% 9 mm glass fiber, 7.5% carboxymethyl cellulose, 7.5% polyvinyl alcohol and 5% stearic acid. ​

Images