Preparation method and application of a catalyst for medium-temperature desulfurization of coke oven gas

Abstract

The application discloses a preparation method and application of a catalyst for medium-temperature desulfurization of coke oven gas, and belongs to the field of catalysts. The preparation method of the catalyst for medium-temperature desulfurization of coke oven gas comprises the following steps: S1, preparing an A metal compound into an A metal salt solution; then adding a molecular sieve into the A metal salt solution, impregnating, filtering and collecting the precipitate; drying to obtain a solid powder; S2, preparing a B metal compound into a B metal salt solution; then adding the solid powder of step S1 into the B metal salt solution, impregnating, filtering and collecting the precipitate; drying and calcining to obtain the medium-temperature desulfurization catalyst. The application selects a molecular sieve with high stability as a carrier, so that the catalyst has high resistance to sulfation, and the service life of the catalyst is prolonged; one metal compound selected from zinc, copper, iron, manganese and cobalt is selected as an active component, so that the hydrogen sulfide conversion rate is ensured; nickel, lanthanum, cerium or silver, platinum is selected as a cocatalyst, so that the use temperature range of the catalyst is widened.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation and use, and relates to a preparation method and application of a catalyst for medium-temperature desulfurization of coke oven gas, and more specifically to a preparation method and application of a hydrogen sulfide selective sulfur production catalyst with higher hydrogen sulfide conversion rate and sulfur recovery rate at medium temperature. Background Art

[0002] Coke oven gas (COG) is an important by-product produced during the coking process in the steel industry. Its main components are hydrogen, methane and carbon monoxide. It is a high calorific value gas used in industrial furnaces.

[0003] Various sulfur-containing pollutants in coke oven gas, such as thiophene, carbon disulfide and hydrogen sulfide (H2S), need to be removed before combustion. Generally, the desulfurization process can be achieved in two steps. Organic sulfides are first converted into H2S through catalytic hydrolysis, and then H2S is removed by a desulfurizer. However, the reaction temperature of catalytic hydrolysis in coke oven gas is usually above 150°C, while the removal of H2S is usually achieved below 60°C. The heating and cooling steps usually require more energy consumption and high costs.

[0004] Organic sulfur hydrolysis technology is relatively mature both domestically and internationally. Therefore, developing a desulfurizer that can remove H2S without cooling is crucial. In other words, H2S can be efficiently removed at a medium temperature of 100-150°C.

[0005] In H2S removal technology, dry desulfurization is more widely used at medium and high temperatures compared with wet desulfurization because it can make full use of the temperature of coke oven gas while avoiding corrosion of subsequent equipment and pipelines, including adsorption and oxidation.

[0006] Considering the relatively high temperature and oxygen-containing atmosphere of coke oven gas, H2S selective catalytic oxidation (H2S-SCO) is more suitable for medium-temperature desulfurization of coke oven gas. Based on the reaction between H2S and O2, the toxic H2S can be converted into useful elemental sulfur, not only removing pollutants but also producing value-added products. Summary of the Invention

[0007] In order to overcome the above-mentioned defects in the prior art, the present invention provides a preparation method and application of a catalyst for medium-temperature desulfurization of coke oven gas. The present invention selects a highly stable molecular sieve as a carrier, which makes the catalyst highly resistant to sulfation and can extend the service life of the catalyst; selects a metal compound selected from zinc, copper, iron, manganese and cobalt as the active ingredient to ensure the conversion rate of hydrogen sulfide; selects nickel, lanthanum, cerium or silver, platinum as a co-catalyst to ensure a high sulfur recovery rate and broaden the operating temperature range of the catalyst. The present invention can actively promote the development and promotion of the selective oxidation of medium-temperature hydrogen sulfide in coke oven gas to sulfur, with good economic and environmental benefits.

[0008] To achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A method for preparing a medium-temperature desulfurization catalyst for coke oven gas comprises the following steps:

[0010] S1. Add the molecular sieve to the metal salt solution A, impregnate, filter, collect the precipitate; and obtain a solid powder after drying;

[0011] S2. Add the solid powder obtained in step S1 to the metal salt solution B, immerse, filter, and collect the precipitate; and then dry and calcine to obtain the medium-temperature desulfurization catalyst.

[0012] The preparation method of the A metal salt solution comprises the following steps:

[0013] Add metal compound A to deionized water and stir at room temperature for 15-20 minutes to obtain a metal salt solution A.

[0014] In step S1, the mass ratio of the metal compound A to the molecular sieve is 15%-50%.

[0015] The A metal includes at least one of zinc, copper, iron, manganese and cobalt.

[0016] Preferably, the A metal is iron.

[0017] The preparation method of the B metal salt solution comprises the following steps:

[0018] Add the B metal compound to deionized water and stir at room temperature for 15-20 minutes to obtain a B metal salt solution.

[0019] The mass ratio of the B metal compound to the molecular sieve is 0.5%-15%.

[0020] The B metal includes at least one of nickel, lanthanum, cerium, silver, and platinum.

[0021] Preferably, the B metal salt solution is silver.

[0022] The molecular sieve is MCM-41.

[0023] The step S1 specifically comprises: adding metal compound A to deionized water, stirring at room temperature for 15-20 minutes to obtain a metal salt solution A; then adding molecular sieves to the metal salt solution A, and immersing at room temperature for 8-24 hours; filtering, collecting the precipitate, and drying at 60-105° C. for 6-18 hours to obtain the solid powder.

[0024] The step S2 specifically comprises: adding the B metal compound to deionized water, stirring at room temperature for 15-20 minutes to obtain a B metal salt solution; adding the solid powder of step S1 to the B metal salt solution, immersing for 8-24 hours, filtering, drying at 60-105° C. for 6-18 hours, and then calcining at 350-550° C. for 2-5 hours to obtain the catalyst for medium-temperature desulfurization of coke oven gas.

[0025] The present invention provides an application of the desulfurization catalyst, which is used for the medium-temperature selective catalytic oxidation of H2S in coke oven gas; the medium temperature condition is 100-150°C.

[0026] The coking process produces coke oven gas (COG), a significant byproduct in the steel industry. Composed primarily of hydrogen, methane, and carbon monoxide, COG is a high-calorific value fuel gas used in industrial furnaces. However, prior to combustion, various sulfur-containing contaminants, such as thiophene, carbon disulfide, and hydrogen sulfide (H2S), must be removed from COG. Typically, desulfurization involves two steps. First, organic sulfur compounds are converted to H2S using catalytic hydrolysis, followed by removal of the H2S using a desulfurization agent. However, catalytic hydrolysis in COG typically requires high temperatures exceeding 150°C, while H2S removal is typically achieved below 60°C. The heating and cooling steps in this process typically consume significant energy and incur high costs. Notably, organic sulfur hydrolysis technology has been well developed both domestically and internationally. Therefore, developing a desulfurization agent that can remove H2S without requiring cooling is crucial. In other words, it is desirable to efficiently remove H2S at moderate temperatures, between 100°C and 150°C. However, considering the medium-temperature conditions of coke oven gas, more attention should be paid to transition metal catalysts due to their excellent redox ability and high-temperature activity. However, pure transition metal oxides have a relatively low specific surface area and poor pore structure, which limits ion diffusion and mass transfer. Therefore, it is reasonable to load active transition metals on appropriate supports, such as molecular sieve materials, to improve the utilization of active ingredients. SBA-15, 13X, and MCM-41 are commonly used catalyst supports for loading active ingredients for catalytic oxidation reactions. Their large specific surface area and ordered mesoporous structure are conducive to the dispersion and fixation of active metals.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) This study developed an FeAg-MCM41 catalyst for the H2S-SCO process, demonstrating high H2S removal efficiency and sulfur selectivity. The 30Fe-MCM41 catalyst, prepared by an impregnation method, exhibited the highest sulfur capacity at an intermediate temperature of 120°C. Further loading of the catalyst with Ag enhanced the H2S removal efficiency and sulfur selectivity. The synergistic effect of Fe-Ag aggregates on the H2S-SCO process was confirmed by evaluating the H2S-SCO performance, as well as the structural and chemical properties. Furthermore, a potential solution for desulfurization of coke oven gas at intermediate temperatures was proposed, simplifying the traditional hydrolysis-cooling adsorption process to a hydrolysis-oxidation process. This optimized process reduces energy consumption while producing valuable products.

[0029] 2) The present invention uses a highly stable molecular sieve as the carrier MCM-41, which has a higher specific surface area than SBA-15 and 13X, thereby making the catalyst more resistant to sulfation and extending the service life of the catalyst;

[0030] 3) Selecting a metal oxide from zinc, copper, iron, manganese and cobalt as the active ingredient ensures the conversion rate of hydrogen sulfide;

[0031] 4) Selecting nickel, lanthanum, cerium or silver, platinum as the co-catalyst ensures a high recovery rate of sulfur and broadens the operating temperature range of the catalyst.

[0032] 5) The present invention can actively promote the development and promotion of the selective oxidation of medium-temperature hydrogen sulfide in coke oven gas to sulfur, and has good economic and environmental benefits. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0034] In the following embodiments:

[0035] Example 1

[0036] Step 1: Dissolve 0.30 g of Fe(NO3)3·9H2O in 20 ml of deionized water to prepare an Fe salt solution, place the solution in a glass petri dish with a diameter of 75 mm, and then place 1 g of MCM-41 in the Fe salt solution to prepare suspension 1;

[0037] Step 2: placing the suspension 1 in a dry and cool place for 8 hours, then filtering, washing, and drying at 105° C. overnight to obtain a dry solid;

[0038] Step 3: Then, 0.05 g of a metal salt compound (AgNO3) was dissolved in 20 ml of deionized water to prepare an Ag salt solution;

[0039] Step 4: Add the solid dried in step 2 to the Ag salt solution to prepare suspension 2, place the suspension 2 in a dry and cool place for 8 hours, then filter, wash and dry at 105°C overnight; finally, calcine the dried sample at 350°C in air at a heating rate of 5°C / min for 3 hours to obtain the composite supported oxide catalyst 30Fe5Ag-MCM-41.

[0040] Example 2

[0041] Step 1: Dissolve 0.30 g of Fe(NO3)3·9H2O in 20 ml of deionized water to prepare an Fe salt solution, place the solution in a glass petri dish with a diameter of 75 mm, and then place 1 g of MCM-41 in the Fe salt solution to prepare suspension 1;

[0042] Step 2: placing the suspension 1 in a dry and cool place for 8 hours, then filtering, washing, and drying at 105° C. overnight to obtain a dry solid;

[0043] Step 3: 0.05 g of a metal salt compound (AgNO3) was dissolved in 20 ml of deionized water to prepare a dry solid, which was added to the Ag salt solution to prepare a suspension 2. The suspension 2 was placed in a dry and cool place for 8 hours, and then filtered, washed, and dried at 105°C overnight.

[0044] Step 5: calcining the dried sample at 350° C. in air at a heating rate of 5° C. / min for 3 hours to obtain a composite supported oxide catalyst 30Fe5Ag-MCM-41.

[0045] Example 3

[0046] The difference between this embodiment and embodiment 1 is that the metal salt compound in step 3 is replaced with (Mn(NO3)2·4H2O); and a composite supported oxide catalyst 30Fe5Mn-MCM-41 is prepared.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 1 is that the metal salt compound in step 3 is replaced by (Ni(NO3)2·6H2O); and a composite supported oxide catalyst 30Fe5Ni-MCM-41 is prepared.

[0049] Example 5

[0050] The difference between this embodiment and embodiment 1 is that the metal salt compound in step 3 is replaced by (PtCl2); a composite supported oxide catalyst 30Fe5Pt-MCM-41 is prepared.

[0051] Example 6

[0052] The difference between this embodiment and embodiment 1 is that the metal salt compound in step 3 is replaced with (La(NO3)3·6H2O); and a composite supported oxide catalyst 30Fe5La-MCM-41 is prepared.

[0053] Example 7

[0054] The difference between this embodiment and embodiment 1 is that the metal salt compound in step 3 is replaced with (Ce(NO3)3·6H2O); and a composite supported oxide catalyst 30Fe5Ce-MCM-41 is prepared.

[0055] Example 8

[0056] The difference between this embodiment and embodiment 1 is that the amount of AgNO3 used in step 3 is 0.005 g; a composite supported oxide catalyst 30Fe0.5Ag-MCM-41 is prepared.

[0057] Example 9

[0058] The difference between this embodiment and embodiment 1 is that the amount of AgNO3 used in step 3 is 0.01 g; a composite supported oxide catalyst 30Fe1Ag-MCM-41 is prepared.

[0059] Example 10

[0060] The difference between this embodiment and embodiment 1 is that the amount of AgNO3 used in step 3 is 0.025 g; a composite supported oxide catalyst 30Fe2.5Ag-MCM-41 is prepared.

[0061] Example 11

[0062] The difference between this embodiment and embodiment 1 is that the amount of AgNO3 in step 3 is replaced by 0.10 g; a composite supported oxide catalyst 30Fe10Ag-MCM-41 is prepared.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 1 is that MCM-41 in step 1 is replaced by SBA-15; thus, a composite supported oxide catalyst 30Fe5Ag-SBA-15 is prepared.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 1 is that MCM-41 in step 1 is replaced by 13X; thus, a composite supported oxide catalyst 30Fe5Ag-13X is prepared.

[0067] Comparative Example 3

[0068] The specific steps include:

[0069] Step 1: Dissolve 0.05 g of Fe(NO3)3·9H2O in 20 ml of deionized water to prepare solution A. Place solution A in a glass petri dish with a diameter of 75 mm, and then place 1 g of MCM-41 in the above solution to prepare a suspension.

[0070] Step 2: Place the suspension in a dry and cool place for 8 hours, filter, wash and dry at 105°C overnight; finally, calcine the dried sample at 350°C in air at a heating rate of 5°C / min for 3 hours to obtain a series of supported oxide catalysts 5Fe-MCM41.

[0071] Comparative Example 4

[0072] The specific steps include:

[0073] Step 1: Dissolve 0.30 g of Fe(NO3)3·9H2O in 20 ml of deionized water to prepare solution A. Place solution A in a glass petri dish with a diameter of 75 mm, and then place 1 g of MCM-41 in the above solution to prepare a suspension.

[0074] Step 2: Place the suspension in a dry and cool place for 8 hours, filter, wash and dry at 105°C overnight; finally, calcine the dried sample at 350°C in air at a heating rate of 5°C / min for 3 hours to obtain a series of supported oxide catalysts 30Fe-MCM41.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 is that in step 5, the dried sample is calcined at 350° C. in air at a heating rate of 10° C. / min for 3 hours to obtain the composite supported oxide catalyst 30Fe5Ag-MCM-41.

[0077] Comparative Example 6

[0078] The difference between this comparative example and Example 1 is that in step 5, the dried sample is calcined at 400° C. for 3 hours in air at a heating rate of 5° C. / min to obtain a composite supported oxide catalyst, 30Fe5Ag-MCM-41.

[0079] Performance test case

[0080] The catalysts prepared in each example and comparative example were subjected to catalytic activity tests. The catalytic activity evaluation method of the catalysts is as follows:

[0081] Catalytic evaluation of the samples for H2S oxidation was conducted in a fixed-bed quartz reactor with an inner diameter of 6 mm and an outer diameter of 8 mm. 50 mg of catalyst was used in each experiment. The simulated gas consisted of a mixture of 200 ppm H2S and 1 vol% O2, with N2 used as the balance gas at atmospheric pressure. The O2 concentration was analyzed using a Haixin GC-950 (TCD detector) gas chromatograph, while the inlet and outlet H2S and byproduct (SO2) concentrations were analyzed using an Agilent-7890B (FPD detector) gas chromatograph. The stability test conditions remained the same as above, except for the fixed temperature of 120°C. [H2S] in and [H2S] out are the H2S concentrations (ppm) at the inlet and outlet, respectively. catalyst is the mass of the catalyst (g). In addition, the H2S removal efficiency (XH2S) and sulfur selectivity (Ssulfur) are defined according to the following equations:

[0082]

[0083]

[0084] Among them, [SO2] out is the outlet SO2 concentration (ppm).

[0085] The catalytic activities of the catalysts are shown in Table 1 below.

[0086] Table 1

[0087]

[0088] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a catalyst for medium-temperature desulfurization of coke oven gas, characterized in that: The following steps are involved: S1. Add the molecular sieve to the metal salt solution A, impregnate, filter, collect the precipitate; and obtain a solid powder after drying; S2, adding the solid powder of step S1 to the metal salt solution of B, impregnating, filtering, collecting the precipitate; drying and then calcining to obtain the medium-temperature desulfurization catalyst; The preparation method of the A metal salt solution comprises the following steps: Add metal compound A to deionized water and stir at room temperature for 15-20 minutes to obtain a metal salt solution; The metal A is iron; The preparation method of the B metal salt solution comprises the following steps: Add the B metal compound to deionized water and stir at room temperature for 15-20 minutes to obtain a B metal salt solution; The B metal is silver; The molecular sieve is MCM-41; The medium temperature condition is 100-150°C; The mass ratio of the metal compound A to the molecular sieve is 30%; the mass ratio of the metal compound B to the molecular sieve is 5%.

2. A desulfurization catalyst prepared according to the preparation method of claim 1.

3. Use of the catalyst according to claim 2, characterized in that: The application is for medium-temperature selective catalytic oxidation of H2S in coke oven gas; the medium temperature condition is 100-150°C.

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