CN114367279A - Low-temperature poisoning-resistant hydrolysis catalyst for fine desulfurization of blast furnace gas and preparation method thereof - Google Patents

Abstract

The invention discloses a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas and a preparation method thereof. The catalyst is composed of the following components according to the mass percentage: 75%-80% of carrier, 5%-20% of active component, and 1%-5% of auxiliary agent. %, the sum of the mass percentages of the above components is 100%. Wherein, the carrier is an aluminum-titanium composite oxide, the active component is one or more of alkali metal oxides, and the auxiliary agent is one or more of carboxymethyl cellulose, starch, and carbon black. The present invention also relates to a preparation method of the hydrolysis catalyst. The catalyst of the invention has lower hydrolysis reaction temperature, wider catalytic hydrolysis desulfurization activity temperature window, stronger anti-poisoning performance, long service life, and can be directly arranged after the blast furnace gas dedusting step to reduce energy consumption and cost.

Description

Low temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas and preparation method thereof

technical field

The invention belongs to the technical field of blast furnace gas fine desulfurization catalysis, and in particular relates to a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas and a preparation method thereof.

Background technique

Blast furnace gas is one of the main by-products produced in the ironmaking process. It contains abundant carbon monoxide resources and can be enriched and recycled, but its components contain a large amount of organic sulfur compounds and inorganic sulfur compounds, among which the organic sulfur compounds are mainly carbonyl sulfide. , but due to its chemical stability, it is difficult to achieve effective removal by conventional removal methods. In view of increasingly stringent environmental regulations and catalytic technical specifications, the removal of COS is urgent.

COS can be removed by hydroconversion method, oxidation method, adsorption method, physical and chemical absorption method, etc., but these methods have high operating temperature, high energy consumption, and are prone to side reactions.

Another method is catalytic hydrolysis (COS+H ₂ O→H ₂ S+CO ₂ ), which has become widely recognized in the steel industry due to its mild reaction conditions, lower operating temperature and higher removal efficiency COS conversion and removal technology, in which the choice of catalyst is crucial for the removal of COS.

Chinese patent CN112619648A studies a copper-cobalt-based catalyst. The hydrothermal synthesis method requires a high-pressure reactor and has high operational requirements. Chinese patent CN112439409A discloses an organic sulfur hydrolysis catalyst, which supports two-component transition metal oxides on Al ₂ O ₃ , but has low conversion activity for low COS feed gas.

In Chinese patent CN113578329A, a hydrolysis catalyst for removing carbonyl sulfide from blast furnace gas and a preparation method thereof are disclosed. The hydrolysis conversion rate of the modified catalyst at a temperature of 100°C to 150°C reaches more than 80%, and the reaction The temperature is still high; secondly, the sources of raw materials are still not extensive enough, limited to the inorganic field, and not involved in the organic field; thirdly, there is still room for optimization of the preparation method, and the catalyst carrier is prepared first, and the carrier is prepared by the precipitation method. After that, the active component solution is prepared and added to the catalyst carrier, and the impregnation method is performed to obtain the catalyst, which requires a two-stage operation.

SUMMARY OF THE INVENTION

Technical problem to be solved by the present invention: In order to overcome the shortcomings of the prior art, the present invention provides a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas and a preparation method thereof.

Technical scheme of the present invention: the low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to the present invention is composed of the following components according to mass percentage: 75% to 80% of carrier, 5% to 20% of active component, and 1% to 1% of auxiliary agent. 5%, the sum of the mass percentages of the above components is 100%; the carrier is a titanium-aluminum composite oxide, wherein the molar ratio of titanium and aluminum elements is (0.2-0.6): (0.4-1); the titanium-aluminum In the aluminum composite oxide, the precursor of titanium is tetrabutyl titanate; the precursor of aluminum is aluminum isopropoxide. Further, the active component is one or more of oxides of alkali metal elements of the first main group.

Further, the active component includes at least one of oxides of sodium and potassium, wherein the molar ratio of the alkali metal, titanium and aluminum elements is (0.05-0.4):(0.1-0.5):1.

Further, the precursor of the active component includes any one of sodium carbonate, sodium nitrate, sodium acetate, sodium bicarbonate, sodium chloride or potassium carbonate, potassium nitrate, potassium acetate, potassium bicarbonate, potassium chloride .

Further, the auxiliary agent is one or more of carboxymethyl cellulose, starch and carbon black.

The invention also discloses a preparation method of a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas, comprising the following implementation steps:

Step 1. The titanium precursor and the aluminum precursor are sequentially added to deionized water according to a certain molar ratio, and stirred in an ice-water bath until completely dissolved to obtain a mixed solution A;

Step 2, adding the precursor of the active component into the mixed solution A according to a certain molar ratio, stirring until the solution is clear, and obtaining the mixed solution B;

Step 3. Add the auxiliary agent into the mixed solution B according to a certain mass ratio, stir until completely dissolved, and obtain the mixed solution C;

Step 4. Add lye dropwise to the mixed solution C, stir and adjust the pH until the ion precipitation is complete, and obtain the mixed solution D;

Step 5: Sealing the mixed solution D, after aging, washing, suction filtration, drying, grinding, calcining, and cooling to obtain a low-temperature anti-poisoning hydrolysis catalyst.

Further, the stirring can be carried out by using ultrasonic waves, mechanical stirring or a combination thereof, wherein the ultrasonic frequency is 50-100 Hz, the ultrasonic time is 0.5-2 h; the mechanical stirring speed is 200-600 r/min, and the stirring time is 0.5-2 h.

Further, in the fourth step, the alkali solution includes any one of ammonia water, sodium hydroxide and potassium hydroxide, and the pH is controlled at 8-10.

Further, in the step 5, the aging temperature is 25-40° C., and the aging time is 24-48 h.

Further, in the step 5, centrifugal washing can be used for the washing, the rotating speed of the centrifuge is 3000-6000 r/min, and the centrifugation time of each group is 8-15 min; For separation, the vacuum degree of the vacuum pump is maintained at 0.03-0.07Mpa; the drying is drying at 105-120°C for 10-16h; the calcination is calcining at 500-700°C in an air atmosphere for 4-6h.

The beneficial effects of the present invention compared with the prior art:

1. The present invention uses new materials tetrabutyl titanate and aluminum isopropoxide in the organic field as the precursor of the titanium-aluminum composite oxide, so that the selection of the precursor material of the titanium aluminum element is no longer limited to the inorganic field; at the same time, The elemental composition of tetrabutyl titanate is only C, H, O, Ti, and the elemental composition of aluminum isopropoxide is only C, H, O, Al, and does not contain impurity ions; for example, the inorganic precursor titanium tetrachloride contains Impurity Cl needs to be removed by repeated washing in the preparation process of the catalyst, and the use of tetrabutyl titanate can completely eliminate this operation, which is an advantage in the preparation process; in addition, the organic precursor itself has certain molecules. Structure, after mutual dissolution, the two molecular structures build each other, and the arrangement is uniform, which is more innovative in catalyst molecular structure than the uniform dispersion of ions in solution.

2. The present invention uses alkali metal elements as active components, and utilizes the characteristics that alkali metal elements can provide a large amount of alkaline reaction sites, and at the same time, the addition of carboxymethyl cellulose and other auxiliary agents can increase the pore size and specific surface area. Two aspects are used to improve the low temperature activity, so that more than 95% of the COS removal effect can be achieved at 75 °C.

3. The present invention uses organic materials such as carboxymethyl cellulose, starch, and carbon black as pore-enlarging assistants, which can be better mutually dissolved in the organic precursor. In addition, high-temperature calcination can generate a large amount of gas, which can help the catalyst to expand pores and increase the ratio. surface area.

4. Compared with the preparation process commonly used in the prior art to prepare a catalyst carrier first, and then prepare a catalyst by an impregnation method, the preparation method of a low-temperature anti-poisoning hydrolysis catalyst for the fine desulfurization of blast furnace gas disclosed in the present invention, the catalyst carrier element is The precursor and active components are simultaneously prepared into a mixed solution, and then lye is added for simultaneous precipitation to obtain a catalyst, which saves the impregnation link and greatly simplifies the preparation process.

Description of drawings

Fig. 1 is the X-ray powder diffractogram of the catalyst prepared by embodiment 1-4 of the present invention and comparative example;

Fig. 2 is the scanning electron microscope picture of the catalyst prepared by Comparative Example (a) and Example (b);

Fig. 3 is the desulfurization performance curve of the catalyst prepared by embodiment 1-4 and comparative example;

Figure 4 is the hydrogen sulfide yield curve of the catalysts prepared in Examples 1-4 and Comparative Example.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

Example 1

Add 41.2643g of aluminum nitrate nonahydrate and 6.044mL of titanium tetrachloride into 50mL of deionized water in turn, stir mechanically at 300r/min in an ice-water bath for 30min until completely dissolved, then add 1.1662g of anhydrous sodium carbonate to the solution, and then add 1.1662g of anhydrous sodium carbonate to the solution, and then add 1.1662g of anhydrous sodium carbonate to the solution. After stirring for 30min until the solution is clear, add 0.5g of carboxymethyl cellulose and stir fully for 1 hour in 60Hz ultrasound, add ammonia water dropwise to the above mixed solution, stir and adjust the pH to 10; seal the above mixture and place it at 25°C Aged for 36 hours, then taken out and transferred to a centrifuge tank for centrifugal washing with deionized water. The speed of the centrifuge is 3600 r/min, and each group is centrifuged for 12 min. After titrating the supernatant with silver nitrate solution, no white precipitate is produced, that is, the washing is completed. Use a vacuum suction filter to separate the washed mixture from solid and liquid. The vacuum degree of the vacuum pump is 0.07Mpa. Then, the solid is dried in an oven at 105-120 ° C for 15 hours to a constant weight. After crushing and grinding, the obtained solid powder is obtained. It was placed in a muffle furnace and calcined at a temperature of 600 °C for 6 h in an air atmosphere. After cooling, a Na/TiAl ₂ O ₅ catalyst was obtained, which was denoted as catalyst A;

Example 2

Add 41.2643g of aluminum nitrate nonahydrate and 6.044mL of titanium tetrachloride into 50mL of deionized water in turn, stir mechanically at 300r/min for 30min in an ice-water bath until completely dissolved, then add 1.7492g of anhydrous sodium carbonate to the solution, and then add 1.7492g of anhydrous sodium carbonate to the solution. After stirring for 30min until the solution is clear, add 0.5g of carboxymethyl cellulose and stir for 1 hour in 60Hz ultrasonic, add ammonia water dropwise to the above mixed solution, stir and adjust the pH to 10; seal the above mixture and place it at 25°C Aged for 36 hours, then taken out and transferred to a centrifuge tank for centrifugal washing with deionized water. The speed of the centrifuge is 3600 r/min, and each group is centrifuged for 12 min. After titrating the supernatant with silver nitrate solution, no white precipitate is produced, that is, the washing is completed. Use a vacuum suction filter to separate the washed mixture from solid and liquid. The vacuum degree of the vacuum pump is 0.07Mpa. Then, the solid is dried in an oven at 105-120 ° C for 15 hours to a constant weight. After crushing and grinding, the obtained solid powder is obtained. It was placed in a muffle furnace and calcined at a temperature of 600 °C for 6 h in an air atmosphere. After cooling, a Na/TiAl ₂ O ₅ hydrolysis catalyst was prepared, which was denoted as catalyst B;

Example 3

Add 41.2643g of aluminum nitrate nonahydrate and 6.044mL of titanium tetrachloride into 50mL of deionized water in turn, stir mechanically at 300r/min for 30min in an ice-water bath until completely dissolved, then add 1.520g of anhydrous potassium carbonate to the solution, and then add 1.520g of anhydrous potassium carbonate to the solution. After stirring for 30min until the solution is clear, add 0.5g of carboxymethyl cellulose and stir fully for 1 hour in 60Hz ultrasound, add ammonia water dropwise to the above mixed solution, stir and adjust the pH to 10; seal the above mixture and place it at 25°C Aged for 36 hours, then taken out and transferred to a centrifuge tank for centrifugal washing with deionized water. The speed of the centrifuge is 3600 r/min, and each group is centrifuged for 12 min. After titrating the supernatant with silver nitrate solution, no white precipitate is produced, that is, the washing is completed. Use a vacuum suction filter to separate the washed mixture from solid and liquid. The vacuum degree of the vacuum pump is 0.07Mpa. Then, the solid is dried in an oven at 105-120 ° C for 15 hours to a constant weight. After crushing and grinding, the obtained solid powder is obtained. It was placed in a muffle furnace and calcined at a temperature of 600 °C for 6 h in an air atmosphere. After cooling, a K/TiAl ₂ O ₅ hydrolysis catalyst was obtained, which was denoted as catalyst C;

Example 4

Add 41.2643g of aluminum nitrate nonahydrate and 6.044mL of titanium tetrachloride into 50mL of deionized water in turn, mechanically stir at 300r/min for 30min in an ice-water bath until completely dissolved, then add 2.280g of anhydrous potassium carbonate to the solution, and then add 2.280g of anhydrous potassium carbonate to the solution, and then add 2.280g of anhydrous potassium carbonate to the solution. After stirring for 30 min until the solution was clear, add 0.5 g of ammonium carboxymethyl cellulose and fully stir for 1 hour in 60 Hz ultrasound, add ammonia water dropwise to the above mixed solution, stir and adjust the pH to 10; seal the above mixture and place it at 25 ° C Under-age for 36h, then take out and transfer to a centrifuge tank for centrifugal washing with deionized water. The speed of the centrifuge is 3600r/min, and each group is centrifuged for 12min. After titrating the supernatant with silver nitrate solution, no white precipitate is produced, that is, the washing is completed. , use a vacuum suction filter to separate the washed mixture, the vacuum degree of the vacuum pump is 0.07Mpa, and then dry the solid in an oven at 105 ~ 120 ℃ for 15h to constant weight, after crushing and grinding, the obtained solid The powder was placed in a muffle furnace and calcined at a temperature of 600 °C for 6 h in an air atmosphere. After cooling, a K/TiAl ₂ O ₅ hydrolysis catalyst was obtained, which was denoted as catalyst D;

Comparative ratio

Add 41.2643g of aluminum nitrate nonahydrate and 6.044mL of titanium tetrachloride into 50mL of deionized water in turn, mechanically stir at 300r/min for 30min in an ice-water bath to completely dissolve, add ammonia water to the above mixed solution dropwise, stir and adjust the pH to 10 The above mixture was sealed and aged at 25°C for 36h, then taken out and transferred to a centrifuge tank for centrifugal washing with deionized water. The speed of the centrifuge was 3600r/min, and each group was centrifuged for 12min until the supernatant was titrated with silver nitrate solution. After the liquid, no white precipitate is produced, that is, the washing is completed. Use a vacuum suction filter to separate the washed mixture from the solid-liquid. After crushing and grinding, the obtained solid powder was placed in a muffle furnace and calcined at a temperature of 600 °C for 6 hours in an air atmosphere. After cooling, a TiAl ₂ O ₅ hydrolysis catalyst was obtained, which was denoted as catalyst E;

As shown in Figure 1, the X-ray powder diffraction patterns of the catalysts prepared by Examples 1-4 and Comparative Examples, the diffraction peak centers observed at 25.281°, 37.800°, 48.049°, and 53.890° in the figure correspond to (101) , (044), (200), (105) planes are typical _TiO2 diffraction peaks; the diffraction peak centers observed at 19.347°, 45.666°, 66.600° in the figure correspond to (110), (400), ( 440) plane, which is the diffraction peak of γ-Al ₂ O ₃ .

It can be seen from the comparative example and the XRD pattern of the comparative example that the doping of active components does not affect the structure of TiAl ₂ O ₅ .

FIG. 2 is a scanning electron microscope view of the catalysts prepared in Example 4 and Comparative Example. It can be seen from the figure that the TiAl ₂ O ₅ prepared in the comparative example is an agglomerated block structure; while the morphology of the K/TiAl ₂ O ₅ prepared in the example is nano-needle, combined with the (101) plane of D in Figure 1 The intensity is significantly reduced, indicating that there is an interaction between potassium and titanium during the preparation process.

The catalysts obtained in Examples 1-4 and Comparative Examples were analyzed and tested accordingly. The activity and stability results of the catalysts were expressed by the COS removal rate, and the COS concentration was detected by on-line gas chromatography.

The test conditions are as follows: the activity test of COS catalytic hydrolysis is carried out in a fixed-bed quartz tube reactor, the catalyst loading is 0.5 mL, the particle size is 40-60 mesh, the reaction temperature is 50-150 °C, and the continuous detection is performed at each reaction temperature. 2h, the test temperature point interval is 25 ℃. The concentration of COS in the raw material gas is 200mg/m ³ , the volume concentration of O ₂ is 1%, N ₂ is the balance gas, and the total flue gas volume is 200 mL/min; the gases of each channel are gradually mixed by a mass flow meter, and then passed through a water saturator. Add water vapor, and finally enter the air mixer to fully mix; the reactor is a quartz tube with an inner diameter of 10mm, and a vertical tubular heating furnace with a temperature control system provides the reaction temperature environment.

The test results are shown in Figure 3. The hydrolysis catalyst prepared by the present invention has a lower activation temperature and a wider activation temperature window. Among them, the catalyst D prepared in Example 4 has the best catalytic performance, which is obviously better than that of TiAl _{2 O5} catalyst, D improved the COS removal efficiency by 40% at 50 °C, and with the increase of temperature, the COS removal efficiency gradually increased, and the removal efficiency could reach 100% at 75 °C.

It can be seen from Fig. 4 that the hydrolysis catalyst prepared by the present invention has a very high H ₂ S yield. Among them, the H ₂ S yield of the catalyst D prepared in Example 4 is the best, and the H ₂ S yield can reach 75°C. 100%. The high H ₂ S yield indicates that the interaction between the catalyst and H ₂ S is weak, which is conducive to the timely diffusion of H ₂ S from the surface, reducing the adsorption and oxidation of H ₂ S on the surface of the catalyst to generate sulfur species, which may lead to catalyst poisoning, thereby prolonging the catalyst's performance. service life.

The above-mentioned specific embodiments are only to illustrate the technical concept and structural features of the present invention, and the purpose is to enable relevant persons who are familiar with the technology to implement them accordingly. Any equivalent changes or modifications substantially made shall fall within the protection scope of the present invention.

Claims (10)

1. The low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas is composed of the following components according to the mass percentage: 75% to 80% of the carrier, 5% to 20% of the active component, 1% to 5% of the auxiliary, and any of the above components by mass percentage. and is 100%; it is characterized in that: the carrier is a titanium-aluminum composite oxide, wherein the molar ratio of titanium and aluminum elements is (0.2-0.6): (0.4-1); the titanium-aluminum composite oxide Among them, the precursor of titanium is tetrabutyl titanate; the precursor of aluminum is aluminum isopropoxide. 2. A kind of low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 1, characterized in that: the active component is one or more of the oxides of the first main group alkali metal elements kind. 3. A kind of low temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 1, is characterized in that: described active component comprises at least one in oxides of sodium and potassium, wherein, described The molar ratio of alkali metal, titanium and aluminum elements is (0.05-0.4):(0.1-0.5):1. 4. a kind of low temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 3, is characterized in that: the precursor of described active component comprises sodium carbonate, sodium nitrate, sodium acetate, sodium bicarbonate, Any one of sodium chloride or potassium carbonate, potassium nitrate, potassium acetate, potassium bicarbonate, and potassium chloride. 5 . The low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 1 , wherein the auxiliary agent is one or more of carboxymethyl cellulose, starch and carbon black. 6 . 6. A preparation method of a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas, characterized in that, comprising the following steps: Step 1. The titanium precursor and the aluminum precursor are sequentially added to deionized water according to a certain molar ratio, and stirred in an ice-water bath until completely dissolved to obtain a mixed solution A; Step 2, adding the precursor of the active component into the mixed solution A according to a certain molar ratio, stirring until the solution is clear, and obtaining the mixed solution B; Step 3. Add the auxiliary agent into the mixed solution B according to a certain mass ratio, stir until completely dissolved, and obtain the mixed solution C; Step 4. Add lye dropwise to the mixed solution C, stir and adjust the pH until the ion precipitation is complete, and obtain the mixed solution D; Step 5: Sealing the mixed solution D, after aging, washing, suction filtration, drying, grinding, calcining, and cooling to obtain a low-temperature anti-poisoning hydrolysis catalyst. 7. the preparation method of a kind of low-temperature anti-poisoning hydrolysis catalyst for the fine desulfurization of blast furnace gas according to claim 6, is characterized in that: described stirring can adopt ultrasonic wave, mechanical stirring or its combination to carry out, wherein, ultrasonic frequency is 50～100Hz, ultrasonic time is 0.5～2h; mechanical stirring speed is 200～600r/min, and stirring time is 0.5～2h. 8. the preparation method of a kind of low temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 6, is characterized in that: in described step 4, described lye comprises ammoniacal liquor, sodium hydroxide, hydrogen Any one of potassium oxide, the pH is controlled at 8-10. 9 . The method for preparing a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 6 , wherein in the step 5, the aging temperature is 25-40° C., 10 . Aging time is 24 ~ 48h. 10. The preparation method of a low-temperature anti-poisoning hydrolysis catalyst for fine desulfurization of blast furnace gas according to claim 6, characterized in that: in the step 5, centrifugal washing can be used for the washing, and the centrifuge rotating speed is 3000～6000r/min, the centrifugation time of each group is 8～15min; the suction filtration can use a vacuum suction filter for solid-liquid separation, and the vacuum degree of the vacuum pump is kept at 0.03～0.07Mpa; the drying is at 105～120 Drying at ℃ for 10-16 hours; the calcination is calcining at 500-700 ℃ in air atmosphere for 4-6 hours.

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