Preparation method of mesoporous gamma-Al2O3-coated TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis

Abstract

The invention discloses a preparation method of a mesoporous gamma-Al2O3-coated TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis, and relates to the technical field of catalysts. The preparation method comprises the following steps: step 1, preparing TiO2 monomer gel: step 1-1, gradually adding 1.5 g of a triblock copolymer Pluronic F127, 2.4 ml of acetic acid and 3.2 ml of concentrated HCl into 30.0 ml of tetrahydrofuran (THF) to form a mixture; and step 1-2, dropwise adding 3.0 ml of tetrabutyl titanate (TBOT) into the mixture to form a golden yellow solution, vigorously stirring, transferring the white-yellow solution into two volumetric flasks, and heating and storing in a drying oven. The mesoporous gamma-Al2O3-coated TiO2 core-shell structure catalyst is synthesized by adopting an evaporation-induced self-assembly method, the mesoporous gamma-Al2O3-coated TiO2 core-shell structure which is uniform in structure and stable in performance is prepared, mesoporous TiO2 of a shell layer serves as a leaked oxygen removal protective agent, gamma-Al2O3 serves as an organic sulfur hydrolysis catalyst, and the catalyst can be used for COS low-temperature hydrolysis and can be used for low-temperature hydrolysis of COS. The low-temperature condition of actual industrial requirements of the iron and steel industry is met.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for hydrolysis of carbonyl sulfide. Background Art

[0002] Organic sulfur pollutants such as carbonyl sulfide (COS) and carbon disulfide (CS2) are widely present in blast furnace gas produced as a byproduct of the steel industry, waste gas from the carbon-chemical industry, and yellow phosphorus tail gas. They are highly chemically stable, toxic, and corrosive. The high organic sulfur content in blast furnace gas produced as a byproduct of steel enterprises will aggravate the corrosion of gas pipelines and equipment, and will also cause SO2 emissions in the flue gas of downstream users to seriously exceed the standard. Blast furnace gas desulfurization is a difficult problem that is difficult to effectively solve in the industry. The latest industrial policy requires the use of source control methods to implement fine desulfurization of blast furnace gas.

[0003] There is no mature and recognized technical route for blast furnace gas fine desulfurization technology. The catalytic hydrolysis conversion technology developed in recent years has the advantages of not consuming raw gas and less side reactions, and has obvious technical advantages. The catalytic hydrolysis method adopts the "organic sulfur hydrolysis conversion + inorganic sulfur desulfurization" scheme, first hydrolyzing organic sulfur to generate H2S, and then removing inorganic sulfur. The key to the technology is the hydrolysis catalyst. Domestic and foreign research mainly focuses on COS single component and high-temperature Claus process tail gas, mainly using γ-Al2O3, TiO2 or activated carbon as carriers, and adding active components for modification. The modified metal oxide-based catalyst has excellent hydrolysis activity at low temperatures. The introduction of a three-dimensional ordered macroporous structure can significantly improve the hydrolysis activity of the catalyst. Some research groups have also found that mesoporous TiO2 is conducive to the mass transfer of catalytic products and can effectively improve the performance of the catalyst. A branch of Sinopec uses a TiO2-based deoxidation protective agent in combination with a γ-Al2O3 organic sulfur hydrolyzer, which exhibits high conversion activity and hydrolysis activity.

[0004] Blast furnace gas has complex composition, low temperature and high oxygen content. The existing catalysts have shortcomings such as short life and low activity; narrow hydrolysis reaction temperature range, low raw gas space velocity; easy oxygen poisoning, etc. Developing hydrolysis catalysts with high activity, high stability and good anti-poisoning properties under low temperature conditions, and synergistic purification of COS and CS2 has important research significance and practical value for promoting energy conservation and emission reduction in the steel industry. γ-Al2O3 is both a carrier and an active component, but it is easily poisoned by oxygen. Anatase TiO2 has high activity and anti-oxygen poisoning properties, and has been used in the Claus gas desulfurization process, but the pore size is small.

[0005] Therefore, we proposed a method for preparing mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis in order to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for hydrolysis of carbonyl sulfide, so as to solve the problems in the current market raised by the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for hydrolysis of carbonyl sulfide, comprising the following steps:

[0008] Step 1, preparation of TiO2 monomer gel:

[0009] Step 1-1, 1.5 g of triblock copolymer Pluronic F127, 2.4 ml of acetic acid and 3.2 ml of concentrated HCl were gradually added to 30.0 ml of tetrahydrofuran (THF) to form a mixture;

[0010] Step 1-2, 3.0 ml of tetrabutyl titanate (TBOT) was added dropwise to the above mixture to form a golden yellow solution. After vigorous stirring, the white-yellow solution was transferred to two volumetric flasks and heated in an oven to slowly evaporate the THF solvent to obtain a white-yellow gel of spherical F127 / TiO2 composite monomer, which was stored in a drying oven;

[0011] Step 2: Preparation of mesoporous Al2O3@TiO2 core-shell structure:

[0012] Step 2-1, 3.0 g of the above white-yellow gel and 3.0 ml of TMB (trimethylbenzene) were redispersed in 10.0 ml of anhydrous ethanol under stirring, and then glycerol (10.0 mL) was added dropwise until the solution became transparent, and then stirred vigorously;

[0013] Step 2-2, adding AlO(OH) sol to the solution obtained in step 2-1, heating the entire solution in an oil bath at 100° C., stirring gently, and cooling to room temperature;

[0014] Step 2-3, collect the white precipitate from the solution obtained in step 2-2 by centrifugation, wash it with ethanol 3 to 5 times, dry it in an oven, and finally anneal it at 600°C at 10°C / min in an air or nitrogen atmosphere in a muffle furnace for 3 hours to obtain an Al2O3@TiO2 core-shell structure.

[0015] Preferably, in the steps 1-2, the vigorous stirring time is 10 minutes.

[0016] Preferably, in the steps 1-2, the oven heating storage temperature is 45° C. and the heating time is 24 hours.

[0017] Preferably, in step 2-1, the first stirring time is 10 minutes, and the second intense stirring time is 5 minutes.

[0018] Preferably, in step 2-1, the AlO(OH) sol is prepared by dissolving 1.5 g of AlO(OH) in 19.75 ml of anhydrous ethanol and then adding 0.25 ml of concentrated hydrochloric acid.

[0019] Preferably, in step 2-2, the gentle stirring speed is 350 rpm and the stirring time is 6 hours.

[0020] Preferably, in the steps 2-3, the nitrogen atmosphere is used to prevent the collapse of the mesoporous structure and to improve the crystallinity.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts an evaporation-induced self-assembly method to synthesize a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst, and prepares a mesoporous γ-Al2O3@TiO2 core-shell structure with uniform structure and stable performance. The mesoporous TiO2 in the shell layer acts as an oxygen leakage protector, and the γ-Al2O3 acts as an organic sulfur hydrolysis catalyst. The catalyst can be used for low-temperature hydrolysis of COS, meeting the low-temperature conditions actually required by the steel industry, and has good market application prospects.

[0023] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD diagram of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention;

[0025] Figure 2 This is a scanning electron microscope (SEM) image of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention;

[0026] Figure 3 EDS element analysis of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 1 ;

[0027] Figure 4 EDS element analysis of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 2 ;

[0028] Figure 5 EDS element analysis of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 3 ;

[0029] Figure 6 EDS element analysis of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 4 ;

[0030] Figure 7 This is the EDS elemental analysis overall spectrum of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention;

[0031] Figure 8 TEM of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 1 ;

[0032] Fig. 9 TEM of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention Figure 2 ;

[0033] Fig.10 This is a nitrogen adsorption and desorption curve diagram of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention;

[0034] Fig.11 This is a pore size distribution curve of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1 - Fig.11 A method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis comprises the following steps:

[0037] Step 1, preparation of TiO2 monomer gel:

[0038] Step 1-1, 1.5 g of triblock copolymer Pluronic F127, 2.4 ml of acetic acid and 3.2 ml of concentrated HCl were gradually added to 30.0 ml of tetrahydrofuran (THF) to form a mixture;

[0039] Step 1-2, 3.0 ml of tetrabutyl titanate (TBOT) was added dropwise to the above mixture to form a golden yellow solution. After vigorous stirring for 10 minutes, the white-yellow solution (about 40 ml in total) was transferred to two 30*50 mm volumetric flasks and heated in a 45° C. oven for 24 hours to slowly evaporate the THF solvent to obtain a white-yellow gel of spherical F127 / TiO2 composite monomer, which was stored in a drying oven;

[0040] Step 2: Preparation of mesoporous Al2O3@TiO2 core-shell structure:

[0041] Step 2-1, 3.0 g of the above white-yellow gel and 3.0 ml of TMB (trimethylbenzene) were redispersed in 10.0 ml of anhydrous ethanol under stirring for 10 minutes, and then glycerol (10.0 mL) was added dropwise until the solution became transparent, and then vigorously stirred for 5 minutes;

[0042] Step 2-2, add AlO(OH) sol to the solution obtained in step 2-1, heat the whole solution in an oil bath at 100°C, stir for 6 hours under gentle stirring (350rpm), and cool to room temperature; AlO(OH) sol is prepared by dissolving 1.5 g of AlO(OH) in 19.75 ml of anhydrous ethanol and then adding 0.25 ml of concentrated hydrochloric acid dropwise, or by dissolving γ-Al2O3 solid particles in 20 ml of ethanol, and the particle size of the γ-Al2O3 solid particles is not limited;

[0043] Step 2-3, collect the white precipitate from the solution obtained in step 2-2 by centrifugal separation, wash it with ethanol 3 to 5 times, place it in an oven to dry, and finally anneal it in a muffle furnace at 10°C / min to 600°C for 3 hours in an air or nitrogen atmosphere to obtain an Al2O3@TiO2 core-shell structure. The nitrogen atmosphere is used to prevent the collapse of the mesoporous structure and improve the crystallinity.

[0044] The present invention uses γ-Al2O3 as a carrier and TiO2 as an active component, and synthesizes a mesoporous Al2O3@TiO2 composite material with a core-shell structure based on an evaporation induced self-assembly (EISA) method.

[0045] 1. Material Characterization: The following characterizations such as SEM, TEM, BET, and XRD prove that the Al2O3@TiO2 composite material of the present invention has a mesoporous core-shell structure.

[0046] like Figure 1 As shown, compared with the standard spectra (PDF#21-1272 and PDF#10-0425), it can be seen that the main phases of the Al2O3@TiO2 composite material of the present invention are γ-Al2O3 and TiO2;

[0047] like Figure 2-Figure 7As shown, through SEM images combined with EDS element analysis, it is shown that the Al2O3@TiO2 composite material of the present invention is spherical and composed of three elements: Al, Ti, and O. The following table is an EDS element composition analysis table:

[0048]

[0049]

[0050] like Figure 8-Figure 9 As shown, the Al2O3@TiO2 composite material of the present invention is a spherical core-shell structure;

[0051] like Figure 10-11 As shown in FIG. 1 , the BET specific surface area of ​​the Al2O3@TiO2 composite material of the present invention is 109.9519 m 2 / g, and the average pore size measured by the Barrett-Joyner-Halenda (BJH) method is 5.1589 nm.

[0052] 2. Application of COS catalytic hydrolysis

[0053] The mesoporous γ-Al2O3@TiO2 core-shell structure catalyst of the present invention has the mesoporous TiO2 in the shell layer acting as an oxygen leakage protector, and the γ-Al2O3 acting as an organic sulfur hydrolysis catalyst, and is used for catalytic hydrolysis of COS in the blast furnace gas fine desulfurization process.

[0054] The catalytic hydrolysis of the target gas was studied using a γ-Al2O3-based catalyst at a low temperature of <100°C. The reaction equation is as follows:

[0055]

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0057] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis, characterized in that: The following steps are involved: Step 1, preparation of TiO2 monomer gel: Step 1-1, 1.5 g of triblock copolymer Pluronic F127, 2.4 ml of acetic acid and 3.2 ml of concentrated HCl were gradually added to 30.0 ml of tetrahydrofuran (THF) to form a mixture; Step 1-2, 3.0 ml of tetrabutyl titanate (TBOT) was added dropwise to the above mixture to form a golden yellow solution. After vigorous stirring, the white-yellow solution was transferred to two volumetric flasks and heated in an oven to slowly evaporate the THF solvent to obtain a white-yellow gel of spherical F127 / TiO2 composite monomer, which was stored in a drying oven; Step 2: Preparation of mesoporous Al2O3@TiO2 core-shell structure: Step 2-1, 3.0 g of the above white-yellow gel and 3.0 ml of TMB (trimethylbenzene) were redispersed in 10.0 ml of anhydrous ethanol under stirring, and then glycerol (10.0 mL) was added dropwise until the solution became transparent, and then stirred vigorously; Step 2-2, adding AlO(OH) sol to the solution obtained in step 2-1, heating the entire solution in an oil bath at 100° C., stirring gently, and cooling to room temperature; Step 2-3, collect the white precipitate from the solution obtained in step 2-2 by centrifugation, wash it with ethanol 3 to 5 times, dry it in an oven, and finally anneal it at 600°C at 10°C / min in an air or nitrogen atmosphere in a muffle furnace for 3 hours to obtain an Al2O3@TiO2 core-shell structure.

2. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the steps 1-2, the vigorous stirring time is 10 minutes.

3. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the steps 1-2, the oven heating storage temperature is 45° C. and the heating time is 24 hours.

4. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the step 2-1, the first stirring time is 10 minutes, and the second intense stirring time is 5 minutes.

5. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the step 2-1, the AlO(OH) sol is prepared by dissolving 1.5 g of AlO(OH) in 19.75 ml of anhydrous ethanol and then adding 0.25 ml of concentrated hydrochloric acid.

6. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the step 2-2, the gentle stirring speed is 350 rpm and the stirring time is 6 hours.

7. The method for preparing a mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to claim 1, characterized in that: In the steps 2-3, the nitrogen atmosphere is used to prevent the collapse of the mesoporous structure and to improve the crystallinity.

8. Use of the mesoporous γ-Al2O3@TiO2 core-shell structure catalyst for carbonyl sulfide hydrolysis according to any one of claims 1 to 7 in the catalytic hydrolysis of COS in the blast furnace gas fine desulfurization process.

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