Anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas and preparation method thereof

Abstract

The present application relates to a kind of anti-poisoning catalyst for blast furnace gas organic sulfur hydrolysis and its preparation method.Each component is as follows in percentage by weight: active component K2CO3 4-12%;Active component Cs2CO3 2-5%;Catalyst aid MoO3 3-8%;Catalyst aid La2O3 0.5-2%;Molding aid SiO2 1-5%;And composite metal oxide carrier Al2O3-TiO2 68-89.5%, the pore size of the composite metal oxide carrier Al2O3-TiO2 is three channel distribution.First, composite metal oxide carrier is prepared, and after being formed with silicon dioxide, active component and catalyst aid are impregnated to prepare catalyst.The catalyst prepared by the present application has excellent catalytic hydrolysis activity for organic sulfur in blast furnace gas, and has anti-sulfur, anti-chlorine and anti-oxygen poisoning performance and has persistent catalytic oxidation activity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to an anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas and a preparation method thereof. BACKGROUND

[0002] The current steelmaking technology in China mainly adopts blast furnace ironmaking, which accounts for more than 90%. The blast furnace ironmaking technology mainly uses coke and iron ore as raw materials to continuously produce liquid pig iron in a blast furnace. The blast furnace gas mainly contains N2 (more than 40%), CO (about 25%-30%), CO2 (about 15%-20%), hydrocarbon compounds and H2 (about 1%-4%), O2 (about 0.05%-3%), and 7%-10% of H2O and a small amount of sulfides. The inorganic sulfur in the sulfides is mainly hydrogen sulfide (H2S), accounting for about 30%-40%; the organic sulfur is mainly carbonyl sulfide (COS), accounting for about 60%-70%, and a small amount of carbon disulfide (CS2) and mercaptans. The organic sulfur and inorganic sulfur coexist in the blast furnace gas, and the components are complex. According to the sulfur content in the blast furnace gas, the key of desulfurization is the organic sulfur.

[0003] The organic sulfur such as COS has weak acidity and stable structure, and it is difficult to effectively remove it by conventional desulfurization methods. The hydrolysis method has the advantages of low reaction temperature, no consumption of hydrogen source, and few side reactions, and is one of the most promising organic sulfur removal technologies. The catalyst is the core of the hydrolysis reaction, and requires the catalyst to have the characteristics of high activity, good selectivity, and anti-poisoning performance, which is a difficult problem for the catalyst.

[0004] The hydrolysis catalyst mainly uses aluminum-based and titanium-based as the carrier, and then loads active components such as alkali metals. However, the blast furnace gas usually contains a small amount of acidic gases such as HCl and HCN, which can easily cause the rapid deactivation of the traditional K2CO3 / γ-Al2O3-based organic sulfur hydrolysis catalyst; in addition, under the micro-oxygen atmosphere of the blast furnace gas, the poisoning and deactivation of sulfates are also easy to occur, which brings great challenges to the long-period stable operation of the organic sulfur hydrolysis catalyst in the blast furnace gas. The organic sulfur hydrolysis catalysts mostly have the problems of poor resistance to chlorine, sulfur and oxygen poisoning, short service life, narrow temperature window, and catalyst wear during operation, thereby causing unstable system operation and excessive sulfur emission. SUMMARY

[0005] The application is to solve the above problems, and provides an anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas and a preparation method thereof.

[0006] The application adopts the following technical scheme: a catalyst for hydrolysis of organic sulfur in blast furnace gas, each component is in percentage by weight: active component K2CO3 4-12%; active component Cs2CO3 2-5%; catalytic aid MoO3 3-8%; catalytic aid La2O3 0.5-2%; forming aid SiO2 1-5%; and composite metal oxide carrier Al2O3-TiO2 68-89.5%, the composite metal oxide carrier Al2O3-TiO2 has three channel distributions of pore diameter.

[0007] Further, the molar ratio of Al:Ti in the composite metal oxide carrier Al2O3-TiO2 is 3-5:1.

[0008] Further, 10-15% of the composite metal oxide carrier has a pore diameter of 2-3nm, 20-30% has a pore diameter of 4-7nm, and 25-40% has a pore diameter of 8-12nm.

[0009] Further, the catalyst is clover-shaped, spherical or cylindrical.

[0010] Further, the catalyst is spherical with a diameter of 4.5-5mm.

[0011] Further, the compressive strength of the spherical particles of the catalyst is 80-110N / particle.

[0012] A preparation method of an anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas, comprising the following steps:

[0013] (1) according to the stoichiometric ratio, mix aluminum nitrate aqueous solution and titanium acid tetraethyl ether solution in ethyl ether uniformly, slowly add ammonia water to the mixed solution under slow stirring to adjust the pH value to 5.5-6.0, slowly stir for 10-15min; then continue to slowly add ammonia water to adjust the pH value to 7.2-7.8, slowly stir for 10-15min; then add ammonia water to adjust the pH value to 9.0-9.5, slowly stir for 20-30min, filter to obtain a precipitate, dry the precipitate, and then calcine the precipitate under air atmosphere at 100-550℃ to obtain a composite metal oxide precursor Al2O3-TiO2;

[0014] (2) place the composite metal oxide precursor Al2O3-TiO2 powder obtained in step (1) in an HCl atmosphere and age at 200℃ for 2-4h to obtain a composite metal oxide carrier Al2O3-TiO2 powder;

[0015] (3) The obtained composite metal oxide carrier Al2O3-TiO2 powder is mixed with a molding aid SiO2 according to a required amount, then a binder solution is added after molding, and a catalyst carrier with a required shape is obtained after drying and calcination at 100-600°C under an air atmosphere;

[0016] (4) An active component solution is prepared by mixing a potassium carbonate, cesium carbonate and ammonium heptamolybdate mixture according to a stoichiometric ratio, and a lanthanum nitrate aqueous solution is prepared according to a stoichiometric ratio; the catalyst carrier obtained in step (3) is immersed in the active component solution according to an equal amount, dried, then immersed in the lanthanum nitrate aqueous solution according to an equal amount, and a final required catalyst is obtained after drying.

[0017] Further, in step (2), the HCl volume concentration is 1-2%, and the rest is nitrogen.

[0018] Further, the calcination temperature in step (4) is 100-400°C.

[0019] The advantages of the present application are as follows:

[0020] (1) The present application prepares a composite metal oxide Al2O3-TiO2 carrier with more abundant pore structure and larger specific surface area by adjusting the pH value of the solution in sections. 2， Titanium oxide alone as a carrier has a small specific surface area, poor mechanical strength and thermal stability; and aluminum oxide alone as a carrier has poor resistance to sulfur and chlorine poisoning. The Al2O3-TiO2 composite carrier prepared in the present application retains the high specific surface, high strength and good thermal stability of Al2O3, and also has the ability to resist sulfur and chlorine poisoning of the TiO2 carrier, and compared with the Al2O3-TiO2 prepared by a conventional coprecipitation method, the special pore structure distribution by section control is beneficial to improve the low-temperature activity of the catalyst, and beneficial to the desorption of acid gases (H2S, SO2 and HCl, etc.) from the catalyst pores and surface, thereby improving the resistance to poisoning.

[0021] (2) In order to further improve the resistance to chlorine and sulfur poisoning of the catalyst, the Al2O3-TiO2 is subjected to aging treatment with HCl. By introducing chlorine on the composite oxide carrier, the adsorption of acid gases by the catalyst can be reduced. And the active component is loaded after the carrier aging treatment, so the doped Cl will not affect the number and strength of the active sites of the catalyst.

[0022] (3) The application adds Cs2CO3 to the conventional active component K2CO3 to improve the basicity and catalytic activity of the catalyst, so that the activity temperature range of the catalyst is wider and the activation temperature is lower; the auxiliary agent La2O3 can not only improve the activity of the catalyst, but also enrich the acid, basic sites and thermal stability of the catalyst; and the addition of MoO3 can improve the sulfur poisoning resistance of the catalyst, because MoO3 can catalyze the decomposition of sulfate on the surface of the carrier and reduce the deposition of sulfur.

[0023] (4) The application uses a specific amount of molding aid and a composite metal oxide carrier treated with HCl with excellent mechanical properties to mold the catalyst into a specific shape (especially spherical particles) with excellent compressive strength through a simple molding process, so that the deep purification of organic sulfur in the blast furnace flue gas can be met. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of the influence of catalyst activity and temperature in examples 1-4 and comparative examples 1-3 in the application.

[0025] Figure 2 The figure is a schematic diagram of the influence of catalyst and time in examples 1-4 and comparative examples 1-3 in the application. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be further described below with reference to the specific drawings.

[0027] In the examples of the application, the aluminum nitrate nonahydrate is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0028] The titanium tetrabutoxide is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0029] Example 1: A preparation method of an anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas: comprising the following steps:

[0030] (1) In a beaker, 1125 g of aluminum nitrate nonahydrate was dissolved in 5 L of water to obtain an aluminum nitrate solution; 228 g of tetrabutyl titanate was dissolved in 500 mL of ethyl ether to obtain an ethyl ether solution, under the condition of slow stirring, ammonia water was slowly added dropwise to the mixed solution, and the pH was adjusted to 5.5-6.0, and then slowly stirred for 15 min; then ammonia water was continuously added dropwise, the pH was adjusted to 7.2-7.8, and then slowly stirred for 15 min; finally, ammonia water was added dropwise to adjust the pH to 9.0-9.5, and slowly stirred for 30 min, and the precipitate was obtained by filtration under reduced pressure. The precipitate was washed three times with deionized water and ethanol, and then calcined in a muffle furnace at 550°C for 4 h under an air atmosphere to obtain a composite metal oxide precursor Al2O3-TiO2 (Al:Ti = 3:1 based on the molar ratio used).

[0031] (2) The Al2O3-TiO2 precursor obtained above was placed in a fixed bed, and 1% HCl gas was introduced, with nitrogen as the balance gas. Aging treatment was carried out at 200°C for 4 h to obtain a composite metal oxide carrier Al2O3-TiO2 powder, which was crushed to 500 mesh or more;

[0032] (3) 300 g of the crushed powder was added to a small stirrer, and 8 g of white carbon black was added and mixed uniformly, the obtained mixture was placed in the feeder of a rotary table forming machine, and a mixed aqueous solution with a mass concentration of 1% hydroxypropyl methyl cellulose and 2% nitric acid was sprayed by a spray gun to prepare spherical embryos, the obtained spherical embryos were calcined in a muffle furnace at 600°C for 4 h, and naturally cooled to room temperature to obtain spherical carriers; 10-15% of the pore size of the composite metal oxide carrier is 2-3 nm, 20-30% of the pore size is 4-7 nm, and 25-40% of the pore size is 8-12 nm.

[0033] (4) 11.4 g of potassium carbonate, 4.3 g of cesium carbonate, and 6.9 g of ammonium heptamolybdate were weighed into a beaker, and 60 mL of water was added to prepare an active component solution; 2.8 g of lanthanum nitrate was dissolved in 60 mL of water to prepare a lanthanum nitrate solution, 120 g of spherical carriers were first added to the active component solution at 50°C, and naturally air-dried; then the solid was added to the lanthanum nitrate solution at 50°C, and naturally air-dried, and then calcined in a muffle furnace at 400°C for 4 h to obtain the final catalyst. The catalyst is spherical with a diameter of 4.5 mm-5 mm, and the compressive strength of the spherical particles of the catalyst is 80-110 N / particle.

[0034] The mass percentage of each component in the prepared catalyst is: K2CO3 8%, Cs2CO3 3%, MoO3 4%, La2O3 1%, SiO2 2.2%, and Al2O3-TiO2 81.8%. Example 2

[0035] The preparation method is the same as that of Example 1 except that the content of each component is changed.

[0036] The prepared catalyst contains the following components by mass percentage: K2CO3 12%, Cs2CO3 2%, MoO3 8%, La2O3 2%, SiO2 2.5%, and Al2O3-TiO2 73.5%. Example 3

[0037] The preparation method is the same as that of Example 1 except that the content of each component is changed.

[0038] The prepared catalyst contains the following components by mass percentage: K2CO3 4%, Cs2CO3 5%, MoO3 3%, La2O3 0.5%, SiO2 3.2%, and Al2O3-TiO2 84.3%. Example 4

[0039] The preparation method is the same as that of Example 1 except that the content of each component is changed.

[0040] The prepared catalyst contains the following components by mass percentage: K2CO3 7%, Cs2CO3 4%, MoO3 6%, La2O3 1.5%, SiO2 4.3%, and Al2O3-TiO2 77.2%.

[0041] Comparative Example 1

[0042] A commercially available spherical organic sulfur hydrolysis catalyst (catalyst model T504, main active component K2CO3, carrier γ-Al2O3) was selected as Comparative Example 1.

[0043] Comparative Example 2

[0044] In a small stirrer, 197 g of Al2O3 powder and 103 g of TiO2 powder were mechanically stirred and mixed uniformly, and 8 g of white carbon black was added and mixed uniformly. Then, the final product was prepared according to the procedure described in Example 1.

[0045] A single-loaded catalyst was prepared, which contains the following components by mass percentage: K2CO3 8%, Cs2CO3 3%, MoO3 4%, La2O3 1%, SiO2 2.2%, and Al2O3 53.8%. ， TiO2 28%.

[0046] Comparative Example 3

[0047] A composite metal oxide precursor Al2O3-TiO2 was prepared according to the method described in Example 1, but the aging treatment step of HCl was omitted, and then the final product was prepared according to the procedure described in Example 1.

[0048] The single-loaded catalyst was obtained by the above preparation process, and the components were as follows in mass percentage: K2CO3 8%, Cs2CO3 3%, MoO3 4%, La2O3 1%, SiO2 2.2%, and Al2O3-TiO2 81.8%.

[0049] The double-loaded catalysts obtained in Examples 1-4 above and the comparative catalysts obtained in Comparative Examples 1-3 were used respectively, wherein the concentration of carbonyl sulfide (COS) was 500 ppm, the concentration of HCl was 100 ppm, the concentration of SO2 was 100 ppm, and the content of H2O was 5% by volume. The reaction conditions for catalytic hydrolysis were as follows: the space velocity was 20000 h-1, and the content of O2 was 0.3% by volume.

[0050] A fixed bed reactor was used to detect the activity and durability of the catalyst. The carbonyl sulfide and carbon disulfide were simulated by steel cylinder gas, the HCl was prepared into an aqueous solution according to the above metering ratio, and then the solution was atomized and sprayed into the flue by a peristaltic pump (BT100-2J). The O2, N2 and H2S were prepared by steel cylinder gas, the gas flow was controlled by a gas mass flow meter, and the COS concentration at the inlet and outlet of the flue gas was detected by gas chromatography, and finally the conversion rate was calculated. The results are shown in Figure 1 and Figure 2 .

[0051] The results shown in Figures 1-2 indicate that, in the atmosphere containing HCl, SO2 and O2, the catalyst of the present application not only has significantly better catalytic hydrolysis activity or efficiency on COS than the comparative catalysts of Comparative Examples 1, 2 and 3, but also has better resistance to sulfur, chlorine and oxygen poisoning (basically not affected by S and / or Cl and / or O), and therefore has longer durability or catalytic life.

Claims

1. A process for the preparation of an anti-poisoning catalyst for the hydrolysis of organic sulphur of blast furnace gas, characterized by: The catalyst components are as follows in terms of weight percentage: active component K2CO3 4-12%; active component Cs2CO3 2-5%; catalytic assistant MoO3 3-8%; catalytic assistant La2O3 0.5-2%; forming assistant SiO2 1-5%; and composite metal oxide carrier Al2O3-TiO2 68-89.5%, the composite metal oxide carrier Al2O3-TiO2 has a three-channel pore size distribution, the Al:Ti molar ratio in the composite metal oxide carrier Al2O3-TiO2 is 3~5:1, 10~15% of the pore size of the composite metal oxide carrier is 2~3nm, 20~30% of the pore size is 4~7nm, and 25~40% of the pore size is 8-12nm, the catalyst is spherical with a diameter of 4.5mm~5mm, and the compressive strength of the spherical catalyst particles is 80~110 N / particle; The method comprises the following steps: (1) uniformly mixing an aluminum nitrate aqueous solution and a tetraethyl titanate-containing diethyl ether solution according to a stoichiometric ratio, slowly adding ammonia water to the mixed solution under slow stirring to adjust the pH value to 5.5~6.0, slowly stirring for 10~15min, then continuously slowly adding ammonia water to adjust the pH value to 7.2~7.8, slowly stirring for 10~15min, and then adding ammonia water to adjust the pH value to 9.0~9.5, slowly stirring for 20~30min, and filtering to obtain a precipitate, which is dried and calcined at 550℃ in an air atmosphere to obtain a composite metal oxide precursor Al2O3-TiO2; (2) aging the composite metal oxide precursor Al2O3-TiO2 powder obtained in step (1) in an HCl atmosphere at 200℃ for 2~4h to obtain a composite metal oxide carrier Al2O3-TiO2 powder; (3) mixing the obtained composite metal oxide carrier Al2O3-TiO2 powder with a forming assistant SiO2 according to the required amount, then adding a binder solution to form a catalyst carrier with a required shape, and drying and calcining at 100~600℃ in an air atmosphere to obtain the catalyst carrier with the required shape; (4) mixing a potassium carbonate, cesium carbonate and ammonium heptamolybdate mixture according to a stoichiometric ratio to prepare an active component solution, and preparing a lanthanum nitrate aqueous solution according to a stoichiometric ratio; immersing the catalyst carrier obtained in step (3) in the active component solution according to an equal amount, drying, then immersing the catalyst carrier in the lanthanum nitrate solution according to an equal amount, and drying and calcining to obtain the final required catalyst.

2. The method for preparing an anti-poisoning catalyst for hydrolysis of organic sulfur of blast furnace gas according to claim 1, characterized by: In the step (2), the HCl atmosphere has a volume concentration of 1~2%, and the rest is nitrogen.

3. The method for preparing an anti-poisoning catalyst for hydrolysis of organic sulfur in blast furnace gas according to claim 1, characterized by: In the step (4), the calcination temperature is 400℃.

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