Alkali-modified bimetallic oxide catalyst, preparation method and application of alkali-modified bimetallic oxide catalyst in organic sulfur hydrolysis

Abstract

The invention discloses an alkali-modified bimetallic oxide catalyst, a preparation method and application of the alkali-modified bimetallic oxide catalyst in organic sulfur hydrolysis, and belongs to the technical field of gaseous sulfide removal. The preparation method comprises the following steps: firstly, grinding Al2O3 and TiO2 into powder, mechanically and uniformly mixing the powder in proportion, then dipping an alkali metal salt solution on the mixed powder of Al2O3 and TiO2, carrying out uniform ultrasonic treatment, drying, and calcining in air to obtain the catalyst. The preparation method is simple, waste water is not required to be generated by washing, and the environmental protection and production cost is greatly reduced; tiO2 and Al2O3 are mechanically mixed, so that the porous structure and surface hydroxyl of Al2O3 cannot be damaged, and the anti-poisoning performance of the catalyst can be improved by introducing TiO2. The catalyst shows excellent catalytic activity and better stability in COS and CS2 hydrolysis reaction, still has higher hydrolysis activity under the working condition of containing water vapor, O2, CO2 and other impurity gases, has higher desulfurization performance than the same type of catalyst, and has wide industrial application prospects.

Description

Technical field:

[0001] The invention belongs to the technical field of gaseous sulfide removal, and specifically relates to an alkali-modified bimetallic oxide catalyst, a preparation method and application thereof in organic sulfur hydrolysis. Background technology:

[0002] With the acceleration of my country's modernization construction, the demand for major raw materials in manufacturing industries such as steel has also increased rapidly. The blast furnace gas, a combustible byproduct of steel smelting, is also an important secondary energy source. Its main components include 6-12% CO 2 , 28~33% CO, 55~60% N 2 , 1~4% H 2 , 0.2-0.5% hydrocarbons and 200-300mg / m 3 Sulfides, more than 90% of which are organic sulfur, mainly COS, with a small amount of CS 2 Among them, COS and other sulfides are toxic and harmful gases, which not only seriously affect air quality and threaten human health, but also corrode equipment and poison catalysts in industrial applications. Therefore, if we want to achieve high-value utilization of blast furnace gas, we need to completely remove the sulfur-containing gas. 2 The main removal methods include hydrogenation reduction, organic amine adsorption, oxidation, hydrolysis and photolysis. 2 +H 2 O→COS+H 2 S,COS+H 2 O→CO 2 +H 2 S) has the characteristics of low reaction temperature, no consumption of hydrogen source, and few side reactions, and is one of the most promising organic sulfur removal technologies. Catalysts are the key to large-scale application of hydrolysis. It is a difficult problem for hydrolysis catalysts to have high specific surface area, high hydrolysis catalytic activity and high resistance to sulfation. Mixing different types of active components and carriers to prepare composite catalysts is the research and development trend of organic sulfur hydrolysis catalysts.

[0003] Currently, COS, CS 2 The low temperature hydrolysis catalyst is mainly Al 2 O 3 The active alkali metals, alkaline earth metals, transition metal oxides and rare earth metal oxides are loaded as carriers. At the same time, a large number of studies have shown that hydrotalcite, spinel and activated carbon have certain hydrolysis activity. Hydrotalcite is an anionic inorganic metal material with a layered structure. Its surface hydroxyl group is very rich, which can provide a large number of basic sites for COS and CS. 2Hydrolysis reaction; spinel has both acidic and alkaline active centers, stable in nature, and has also been found to be COS and CS 2 Good catalyst for hydrolysis; after surface modification (active precursors such as Mn, Fe, K, Cu and Ce or non-metallic elements such as N, S and P), the basic functional groups on the surface of activated carbon are increased, which can be used as COS and CS 2 Although these new catalysts have certain COS and CS 2 However, there is a problem that the catalyst is easily deactivated under high water vapor concentration and high space velocity, and the industrial production cost of these new catalysts is also higher than that of traditional Al 2 O 3 Based catalyst. 2 O 3 The base catalyst is modified for COS and CS 2 Hydrolysis is a low-cost and efficient method for producing COS and CS that meets current industrial needs. 2 Hydrolysis catalyst.

[0004] Al 2 O 3 As a porous material, it not only has the advantages of large specific surface area, good thermal stability, and high mechanical strength, but also has the advantages of COS and CS 2 The hydrolysis of Al has a catalytic effect, so 2 O 3 The catalyst has become the most intensively studied and widely used type of COS and CS hydrolysis catalyst. 2 Hydrolysis catalysts, but the above-mentioned Al-based 2 O 3 The hydrolysis catalyst is effective for the hydrolysis of COS and CS at a temperature below 100 °C. 2 The catalytic activity of 2 When there are impurities such as COS and CS in the low temperature range, the desulfurization effect will be greatly reduced. 2 Catalysts with high hydrolysis activity and high resistance to impurity gases are currently the primary goals in industrial production. Summary of the invention:

[0005] In order to overcome the above problems, the present invention aims to provide a base-modified bimetallic oxide catalyst, a preparation method and its application in organic sulfur hydrolysis. The base-modified bimetallic oxide catalyst is prepared by a simple method. The obtained catalyst is 2 COS and CS can also be removed efficiently when there are impurity gases such as 2 , further improving the hydrolysis performance of the catalyst.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a base-modified bimetallic oxide catalyst, which is characterized by comprising the following steps:

[0008] (1) Al 2 O 3 and TiO 2 Grind into powder and mix evenly mechanically according to a certain ratio;

[0009] (2) impregnating a certain amount of alkali metal salt solution onto the mixed powder obtained in step (1), and mixing uniformly by ultrasonication;

[0010] (3) drying the powder obtained in step (2) in an oven overnight;

[0011] (4) The powder obtained in step (3) is heated to 300-500° C. and calcined in air to obtain alkali-modified TiO 2 -Al 2 O 3 Bimetallic catalysts.

[0012] Based on the above technical solution, further, in step (1), Al 2 O 3 and TiO 2 The mass ratio range is 80:20 ~ 98:2, and the grinding time is 10min ~ 30min.

[0013] Based on the above technical solution, further, the alkali metal salt in step (2) is one or a combination of two or more of potassium carbonate, sodium carbonate, potassium bicarbonate or sodium bicarbonate; the amount of alkali metal is Al 2 O 3 and TiO 2 The amount of the ultrasonic treatment is 2% to 10% of the total mass, and the ultrasonic time is 10min to 30min.

[0014] Based on the above technical solution, further, in step (3), the drying temperature is 60 to 120° C., and the drying time is 12 to 24 hours.

[0015] Based on the above technical solution, further, in step (4), the calcination time is 2 to 10 hours, and the heating rate is 2 to 10° C. / min.

[0016] Another aspect of the present invention provides a base-modified bimetallic oxide catalyst prepared by the above preparation method.

[0017] The present invention also provides application of the base-modified bimetallic oxide catalyst in the hydrolysis of organic sulfur.

[0018] Based on the above technical solution, further, the base-modified bimetallic oxide catalyst is applied to COS and CS 2 Hydrolysis reaction or application to COS and CS under working conditions containing impurities 2 Hydrolysis reaction.

[0019] Based on the above technical solution, further, the impurity gas includes O 2 and CO 2 .

[0020] The significant advantages of the present invention compared with the prior art are:

[0021] (1) The synthesis method of the base-modified bimetallic oxide catalyst of the present invention is simple, the raw materials are easily available, only a small amount of water is required during the preparation process, and no washing is required to generate wastewater, which can greatly reduce environmental protection and production costs.

[0022] (2) In the present invention, TiO 2 The introduction of the mechanical mixing method will not destroy the Al 2 O 3 The porous structure and surface hydroxyl groups will not damage the Al 2 O 3 The intrinsic activity of the catalyst is enhanced, and the alkali metal after loading has a higher dispersibility. The surface of the synthesized catalyst also has more alkaline sites, which is conducive to the hydrolysis reaction. 2 The introduction of MgO significantly improves the catalyst's anti-poisoning ability.

[0023] (3) The catalyst prepared by the present invention has the advantages of COS and CS 2 It exhibits excellent catalytic activity and good stability in the hydrolysis reaction, and can 2 and CO 2 , it still has high hydrolysis activity under the working conditions of impurity gases. Description of the drawings:

[0024] Figure 1 is K of Example 2 + Loaded 5% TiO 2 -Al 2 O 3 Scanning electron microscope images of the bimetallic catalyst, where a: the electron microscope image with a scale of 5 μm, b: the electron microscope image with a scale of 2 μm.

[0025] Figure 2 Commercial Al for Comparative Example 1 2 O 3 Scanning electron microscope images of the catalyst, where a: the electron microscope image with a scale of 5 μm, b: the electron microscope image with a scale of 2 μm. Specific implementation method:

[0026] The specific implementation method of the present invention is described in detail below. The specific implementation method described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0027] Example 1

[0028] 0.95 g Al 2 O 3 Catalyst and 0.05 g TiO 2 The catalyst was mechanically ground and mixed to prepare a catalyst containing TiO 2 and Al 2 O 3 The bimetallic oxide catalyst (5% TiO 2 -Al 2 O 3 ), recorded as sample A.

[0029] Example 2

[0030] 0.95 g Al 2 O 3 Catalyst and 0.05 g TiO 2 The catalyst was mechanically ground and mixed to prepare a catalyst containing TiO 2 and Al 2 O 3 The bimetallic oxide catalyst (5% TiO 2 -Al 2 O 3 ), and then 0.0734g of K 2 CO 3 Completely dissolved in 5 mL of deionized water and evenly immersed in 5% TiO 2 -Al 2 O 3 The catalyst was uniformly dispersed by ultrasonication for 30 min, and then dried in an oven at 60 °C overnight. The dried sample was heated to 450 °C at a rate of 5 °C / min in air and maintained for 3 h to obtain 5% K + Loaded 5% TiO 2 -Al 2 O 3 The catalyst was recorded as sample B.

[0031] Figure 1 5% K of Example 2 + Loaded 5% TiO 2 -Al 2 O 3 The SEM image of the catalyst shows an irregular block structure.

[0032] Example 3

[0033] 0.95 g Al 2 O 3 Catalyst and 0.05 g TiO 2 The catalyst was mechanically ground and mixed to prepare a catalyst containing TiO 2 and Al 2 O 3 The bimetallic oxide catalyst (5% TiO 2 -Al 2 O 3 ), and then 0.1174g of K 2 CO 3 Completely dissolved in 5 mL of deionized water and evenly immersed in 5% TiO 2 -Al 2 O 3 The catalyst was uniformly dispersed by ultrasonication for 30 min, and then placed in an oven at 60 °C for drying overnight. The dried sample was heated to 450 °C at a rate of 5 °C / min in air and maintained for 3 h to obtain 8% K + Loaded 5% TiO 2 -Al 2 O 3 The catalyst was recorded as sample C.

[0034] Comparative Example 1

[0035] Commercial Al 2 O 3 The catalyst was recorded as sample D.

[0036] Figure 2 Commercial Al for Comparative Example 1 2 O 3 The SEM image of the catalyst shows an irregular block structure.

[0037] Comparative Example 2

[0038] Commercial TiO 2 The catalyst was recorded as sample E.

[0039] Example 4

[0040] The catalyst prepared above was used to carry out COS and CS 2 Hydrolysis reaction, wherein the catalyst loading is 200 mg, the total reaction gas flow rate is 20 mL / min, and the reaction temperature is 170°C. COS with a concentration of 100 ppm and CS with a concentration of 100 ppm 2 The raw gas also contains 0.5% O 2 ,2.5%CO 2 and 30% water vapor impurity gas, Ar is the balance gas. COS and CS 2The conditions of the hydrolysis reaction and the results obtained are shown in Tables 1 and 2.

[0041] COS conversion rate (%) and CS 2 The calculation formula of conversion rate (%) is as follows:

[0042] COS conversion rate (%) = (COS concentration in feed gas - COS concentration in outlet gas) / COS concentration in feed gas × 100%;

[0043] CS 2 Conversion rate (%) = (CS in raw gas 2 Concentration of CS in the discharge gas 2 Concentration of CS in raw gas 2 concentration × 100%.

[0044] Table 1. Conversion rate of COS hydrolysis of catalysts prepared in Examples 1-3 and Comparative Examples 1-2 (%)

[0045]

[0046] As can be seen from Table 1, commercial Al 2 O 3 The catalyst has a certain COS hydrolysis performance due to its surface hydroxyl groups, but the performance decreased significantly after 25 hours of reaction. The conversion rate dropped to 68.9% after 25 hours of reaction. This may be because the impurity gas contained in the reaction gas destroyed the active sites of the catalyst and reduced its catalytic performance. 2 After that, the COS hydrolysis performance of the catalyst was improved, and then K + The COS hydrolysis performance of the catalyst is further improved. After 25 hours of reaction, the COS conversion rate still remains at 100% without decreasing. After 35 hours of reaction, the COS conversion rate still reaches more than 95%, indicating that the COS hydrolysis activity of the organic sulfur hydrolysis catalyst for blast furnace gas prepared by the present invention is more stable, indicating that its ability to resist acidic gases and impurity gases is stronger and its stability is better.

[0047] Table 2. CS of the catalysts prepared in Examples 1-3 and Comparative Examples 1-2 2 Conversion rate of hydrolysis (%)

[0048]

[0049] As can be seen from Table 2, commercial Al 2 O 3 and commercial TiO 2 Catalysts all have a certain CS 2 hydrolysis ability, but the overall performance is poor, 5% TiO 2 Introduced into Al 2O 3 The catalyst can improve its hydrolysis of CS 2 The performance of K + Introduced into 5% TiO 2 -Al 2 O 3 After the middle, its CS 2 The hydrolysis performance was significantly improved. In the presence of various impurity gases, the CS content was still 55% after 25 h of reaction. 2 Conversion rate. Description K + After the introduction, the hydrolysis performance of the catalyst is improved, and its ability to resist acidic gases and impurity gases is also effectively enhanced.

[0050] In summary, the base-modified bimetallic oxide catalyst prepared in the present invention has high COS and CS 2 Hydrolysis performance is higher than commercial Al 2 O 3 and commercial TiO 2 catalyst, and TiO 2 The introduction of the mechanical mixing method is simple, the raw materials are easily available, only a small amount of water is needed in the preparation process, and no washing is required to produce wastewater, which can greatly reduce environmental protection and production costs; and mechanical mixing will not destroy Al 2 O 3 The porous structure and surface hydroxyl groups of the Al2O3 make it difficult for the sulfate produced during the hydrolysis process to block the pores and surface and will not damage the Al2O3 2 O 3 The intrinsic activity of the catalyst and the K + The high dispersibility makes the surface of the synthesized catalyst have more basic sites, which is beneficial to the hydrolysis reaction.

Claims

1. A method for preparing a base-modified bimetallic oxide catalyst, characterized in that: The steps include: (1) Grinding Al2O3 and TiO2 into powders and mechanically mixing them in a certain proportion; (2) impregnating a certain amount of alkali metal salt solution onto the mixed powder obtained in step (1), and mixing uniformly by ultrasonication; (3) drying the powder obtained in step (2) in an oven overnight; (4) The powder obtained in step (3) is heated to 300-500° C. in air and calcined to obtain an alkali-modified TiO2-Al2O3 bimetallic catalyst.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of Al2O3 to TiO2 is in the range of 80:20 to 98:2, and the grinding time is in the range of 10 min to 30 min.

3. The preparation method according to claim 1, characterized in that: The alkali metal salt in step (2) is one or a combination of two or more of potassium carbonate, sodium carbonate, potassium bicarbonate or sodium bicarbonate; the amount of alkali metal is 2% to 10% of the total mass of Al2O3 and TiO2, and the ultrasonic time is 10min to 30min.

4. The preparation method according to claim 1, characterized in that: In step (3), the drying temperature is 60 to 120° C. and the drying time is 12 to 24 hours.

5. The preparation method according to claim 1, characterized in that: In step (4), the calcination time is 2 to 10 hours, and the heating rate is 2 to 10° C. / min.

6. A base-modified bimetallic oxide catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the base-modified bimetallic oxide catalyst according to claim 6 in the hydrolysis of organic sulfur.

8. The use according to claim 7, characterized in that: The base-modified bimetallic oxide catalyst is applied to the COS and CS2 hydrolysis reaction or to the COS and CS2 hydrolysis reaction under the working condition of impurity gas.

9. The use according to claim 8, characterized in that: The impurity gases include O2 and CO2.

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