A sulfur recovery catalyst and its preparation method

Abstract

This invention belongs to the field of catalyst technology, specifically relating to a sulfur recovery catalyst and its preparation method. The sulfur recovery catalyst uses Al2O3 as a support and is loaded with TiO2, Fe2O3, and Al. x O y Wherein A is selected from at least one of alkali metals or alkaline earth metals; by mass fraction, TiO2 content is 1wt%~15wt%, Fe2O3 content is 0.5wt%~10wt%, and A... x O y The content is 0.1wt%~5wt%, with the remainder being Al2O3. This invention uses shaped alumina as a support to ensure the mechanical strength and appropriate catalytic activity of the catalyst. Secondly, Ti-Fe-A is formulated into a stable composite complex and loaded onto the support through co-impregnation. Calcination then allows the components to be cross-distributed at the atomic level, ensuring interconnection between reactions. This improves the overall activity of the catalyst and extends its service life.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a sulfur recovery catalyst and its preparation method. Background Technology

[0002] In petroleum refining and coal chemical production industries, large amounts of hydrogen sulfide-containing acidic gas are generated. The Claus process is generally used to selectively oxidize the hydrogen sulfide into elemental sulfur for recovery, achieving resource recycling while protecting the environment. The Claus sulfur recovery process typically involves two steps: first, one-third of the H2S is placed in a combustion furnace and reacted at above 800°C to generate SO2; then, the SO2 reacts with the remaining two-thirds of the H2S under the action of a Claus sulfur recovery catalyst to generate elemental sulfur (S). x The specific reactions are as follows:

[0003] H₂S + 3 / 2O₂ = SO₂ + H₂O + Q (1)

[0004] 2H2S + SO2 = 3 / XS x +2H₂O+Q (2)

[0005] H2S + CO2 = COS + H2O + Q (3)

[0006] 2H₂S + CO₂ = CS₂ + 2H₂O + Q (4)

[0007] Reaction (1) is carried out in a Claus combustion furnace (above 800°C). Since the acid gas contains CO2, reactions (3) and (4) also occur simultaneously in the combustion furnace. The carbonyl sulfide and carbon disulfide generated cannot be converted into sulfur through reaction (2). They must be converted into sulfur through hydrolysis on the sulfur recovery catalyst, which is the reverse reaction of reactions (3) and (4), to generate hydrogen sulfide, which is then converted into sulfur through reaction (2). Therefore, this process requires the sulfur recovery catalyst to not only have the activity of catalyzing reaction (2) but also the activity of hydrolyzing organic sulfur. In addition, the feed gas generated by reaction (1) contains a small amount of oxygen, which is called oxygen leakage in industry. This can easily cause sulfation of the sulfur recovery catalyst, leading to the destruction of the catalyst structure. Therefore, the sulfur recovery catalyst must have deoxygenation activity and resistance to sulfation.

[0008] Chinese invention patent application CN101069852A discloses a sulfur recovery catalyst, comprising 65-85% titanium dioxide, 10-30% aluminosilicate, and 1-5% ammonium sulfate. The catalyst is prepared by mixing metatitanic acid and aluminosilicate, then loading ammonium sulfate onto the mixture, followed by drying and calcination. However, this method does not effectively address the catalyst's deoxygenation performance. Chinese invention patent application CN102319565A discloses another sulfur recovery catalyst, using alumina as a support and employing a two-stage impregnation method to load ferrous sulfate and alkaline earth metal salts onto it, followed by drying and calcination. This catalyst comprises 4-5% Fe₂O₃ and 0.15-0.5% alkaline earth metal. Because the catalyst is sequentially impregnated with ferrous sulfate and alkaline earth metal, the alkaline earth metal covers the iron salt, which also negatively impacts the catalyst's oxygen resistance. Chinese invention patent application CN108097257A discloses a sulfur recovery catalyst. It uses boehmite and metatitanic acid as raw materials to prepare a support, then impregnates it with lanthanum, iron, and potassium in three stages, drying after each impregnation, and finally calcining to obtain the sulfur recovery catalyst. The composition is: alumina 40-60%, titanium oxide 40-60%, lanthanum 0.5-5%, iron 1-5%, and potassium 0.2-2%. This method has the same problem as the previous patent, negatively impacting the catalyst's oxygen resistance. Chinese invention patent application CN103111305B discloses a sulfur recovery catalyst using a mixture of ZrO2, TiO2, and SiO2 as a support, coated with ZnO, MnO, Fe2O3, and Cr2O3. Finally, Pd or Pt is loaded to prepare a sulfur recovery catalyst, claiming hydrolysis rates of 99% for COS and 70% for CS2. The biggest problem with this patent is the high cost due to the use of precious metals Pd or Pt, hindering its industrial application.

[0009] Therefore, it is essential to develop a multifunctional catalyst that can promote the reaction of SO2 and H2S, while also possessing oxygen resistance, organic sulfur hydrolysis activity, and sulfation resistance. Summary of the Invention

[0010] To address the shortcomings of the prior art, this invention provides a sulfur recovery catalyst and its preparation method. This catalyst is suitable for the Claus recovery process of H2S in acidic gases and can effectively improve the catalyst's organic sulfur hydrolysis performance, deoxygenation performance, and resistance to sulfation.

[0011] The specific plan is as follows:

[0012] A sulfur recovery catalyst, using Al2O3 as a support, and loaded with TiO2, Fe2O3 and A x O yA is selected from at least one of alkali metals or alkaline earth metals, preferably Ca, Mg, Ba, Na, or K.

[0013] Furthermore, in the sulfur recovery catalyst, the content of TiO2 is 1wt%~15wt%, the content of Fe2O3 is 0.5wt%~10wt%, and the content of A is... x O y The content is 0.1wt%~5wt%, with the remainder being Al2O3.

[0014] A method for preparing a sulfur recovery catalyst includes the following steps:

[0015] S1 uses oxalic acid, hydrogen peroxide and titanium dioxide to prepare a mixed aqueous solution, and reacts to obtain solution A;

[0016] S2 prepares aqueous solution B using complexed iron salt and salt containing A;

[0017] S3. The solution A obtained in step S1 and the aqueous solution B obtained in step S2 are mixed to obtain a Ti-Fe-A composite complex solution, which is then impregnated with an Al2O3 support and calcined to obtain the sulfur recovery catalyst.

[0018] Furthermore, in step S1, the molar ratio of TiO2, H2C2O4, H2O2, and H2O is 1:(1~3):(2~5):(10~100).

[0019] Furthermore, in step S1, the reaction temperature is 20~90℃ and the reaction time is 1~20h.

[0020] Preferably, the titanium oxide is anatase nano-titanium oxide with an average particle size of 1~200 nm.

[0021] Furthermore, in step S2, the complexed iron salt is selected from at least one of EDTA ferric ammonium, EDTA ferric sodium, and ferric citrate; the salt containing A is selected from at least one of soluble salts, preferably nitrates, chlorides, acetates, and carbonates.

[0022] Furthermore, in step S2, the molar ratio of the complexed iron salt, the salt containing A, and H2O is 1:(0.25~5):(10~50).

[0023] Furthermore, in step S3, the calcination temperature is 400~700℃ and the time is 1~20h.

[0024] Preferably, in step S3, the Al2O3 support is γ-Al2O3 or δ-Al2O3, and its shape is at least one of spherical, strip-shaped, sheet-shaped, or Raschig ring-shaped.

[0025] Preferably, in step S3, drying is performed before calcination; the drying temperature is 90~150℃ and the time is 1~10h.

[0026] Beneficial effects:

[0027] This invention provides a sulfur recovery catalyst by formulating a stable Ti-Fe-A composite complex, loading it onto a support using a co-impregnation method, and then calcining it. This method avoids the drawbacks of catalyst preparation methods such as component separation, catalyst poisoning and deactivation, and significant decrease in catalyst mechanical strength due to high titanium oxide content. This invention ensures close contact and synergistic effect of the components at the atomic level, effectively improving the catalyst's activity, organic sulfur hydrolysis performance, deoxidation performance, and sulfation resistance. The use of shaped alumina as a support ensures the catalyst's mechanical strength and appropriate catalytic activity. Furthermore, the Ti-Fe-A is formulated into a stable composite complex using a special method, loaded onto the support via co-impregnation, and then calcined to ensure the components are cross-distributed at the atomic level, guaranteeing the interconnection between reactions. This improves the overall catalyst activity and extends its lifespan. Detailed Implementation

[0028] The embodiments of the present invention will be described in further detail below. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0029] Example 1

[0030] Weigh 33g of oxalic acid (H2C2O4), add 70g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 15g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 50nm and add it to the above solution. Heat to 60℃ and stir for 4h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 20 15g of FeN3O8 and 5g of calcium nitrate (Ca(NO3)2) were dissolved in 15mL of deionized water; the two solutions were mixed and 100g of strip-shaped alumina (γ-Al2O3) was added for complete absorption; the mixture was dried at 110℃ for 10h and calcined at 550℃ for 5h to obtain the sulfur recovery catalyst.

[0031] The sulfur recovery catalyst contains 12.5 wt% TiO2, 2.75 wt% Fe2O3, 1.42 wt% CaO, and the remainder is Al2O3.

[0032] Example 2

[0033] Weigh 22g of oxalic acid (H2C2O4), add 40g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 10g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 100nm and add it to the above oxalic acid solution. Heat to 50℃ and stir for 5h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 20 30g of FeN3O8 and 15g of calcium nitrate (Ca(NO3)2) were dissolved in 35mL of deionized water; the two solutions were mixed and 100g of strip-shaped alumina (γ-Al2O3) was added for complete absorption; the mixture was dried at 120℃ for 6h and calcined at 600℃ for 3h to obtain the sulfur recovery catalyst.

[0034] The sulfur recovery catalyst contains 8.21 wt% TiO2, 5.42 wt% Fe2O3, 4.21 wt% CaO, and the remainder is Al2O3.

[0035] Example 3

[0036] Weigh 35g of oxalic acid (H2C2O4), add 60g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 12.5g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 30nm and add it to the above oxalic acid solution. Heat to 70℃ and stir for 4h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 20 35g of FeN3O8 and 5g of potassium carbonate (K2CO3) were dissolved in 25mL of deionized water; the two solutions were mixed and 100g of strip-shaped alumina (γ-Al2O3) was added for complete absorption; the mixture was dried at 100℃ for 10h and calcined at 500℃ for 5h to obtain the sulfur recovery catalyst.

[0037] The sulfur recovery catalyst contains 10.1 wt% TiO2, 6.23 wt% Fe2O3, 2.75 wt% K2O, and the remainder is Al2O3.

[0038] Example 4

[0039] Weigh 25g of oxalic acid (H2C2O4), add 40g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 10g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 50nm and add it to the above oxalic acid solution. Heat to 60℃ and stir for 5h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 2040g of FeN3O8 and 7g of potassium carbonate (K2CO3) were dissolved in 35mL of deionized water; the two solutions were mixed and 100g of strip-shaped alumina (γ-Al2O3) was added for complete absorption; the mixture was dried at 110℃ for 10h and calcined at 550℃ for 5h to obtain the sulfur recovery catalyst.

[0040] The sulfur recovery catalyst contains 8.09 wt% TiO2, 7.12 wt% Fe2O3, 3.85 wt% K2O, and the remainder is Al2O3.

[0041] Comparative Example 1

[0042] Weigh 15g of anatase-type nano-titanium oxide with an average particle size of 50nm, and weigh 150g of pseudoboehmite powder (containing 66wt% Al2O3). Mix the two materials thoroughly, add 65mL of 5wt% nitric acid aqueous solution, knead, extrude, dry at 110℃ for 5h, and calcine at 550℃ for 4h to obtain TiO2-Al2O3 support; weigh EDTA iron ammonium (C 10 H 20 15g of FeN3O8 and 5g of calcium nitrate (Ca(NO3)2) were mixed and dissolved in 60mL of deionized water; the above strip-shaped support was added for complete absorption; the mixture was dried at 110℃ for 10h and calcined at 550℃ for 5h to obtain the catalyst.

[0043] The catalyst contains 12.5 wt% TiO2, 2.75 wt% Fe2O3, 1.42 wt% CaO, and the remainder is Al2O3.

[0044] Comparative Example 2

[0045] Weigh 22g of oxalic acid (H2C2O4), add 40g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 10g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 100nm and add it to the above oxalic acid solution. Heat to 60℃ and stir for 4h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 20 30g of FeN3O8 and 15g of calcium nitrate (Ca(NO3)2) were dissolved in 20mL of deionized water. The two solutions were mixed, and 150g of pseudoboehmite powder (containing 66wt% Al2O3) was added. The mixture was kneaded, extruded, dried at 110℃ for 5h, and calcined at 600℃ for 4h to obtain the catalyst.

[0046] The catalyst contains 8.21 wt% TiO2, 5.42 wt% Fe2O3, 4.21 wt% CaO, and the remainder is Al2O3.

[0047] Comparative Example 3

[0048] Weigh 12.5g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 30nm, and weigh 150g of pseudoboehmite powder (containing 66wt% Al2O3). Mix the two materials thoroughly, add 65mL of 5wt% nitric acid aqueous solution, knead, extrude, dry at 110℃ for 5h, and calcine at 550℃ for 4h to obtain TiO2-Al2O3 support; weigh EDTA iron ammonium (C 10 H 20 35g of FeN3O8 and 5g of potassium carbonate (K2CO3) were mixed and dissolved in 60mL of deionized water; TiO2-Al2O3 support was added and impregnated until complete absorption; the mixture was dried at 110℃ for 10h and calcined at 500℃ for 5h to obtain the catalyst.

[0049] The catalyst contains 10.1 wt% TiO2, 6.23 wt% Fe2O3, 2.75 wt% K2O, and the remainder is Al2O3.

[0050] Comparative Example 4

[0051] Weigh 25g of oxalic acid (H2C2O4), add 40g of hydrogen peroxide (H2O2 content 27wt%), and dissolve in 10mL of deionized water. Weigh 10g of anatase-type nano-titanium oxide (TiO2) with an average particle size of 50nm and add it to the above oxalic acid solution. Heat to 60℃ and stir for 4h to obtain a transparent solution for later use. Weigh EDTA ferric ammonium (C 10 H 20 40g of FeN3O8 and 7g of potassium carbonate (K2CO3) were dissolved in 35mL of deionized water. The two solutions were mixed, and 150g of pseudoboehmite powder (containing 66wt% Al2O3) was added. The mixture was kneaded, extruded, dried at 110℃ for 5h, and calcined at 550℃ for 5h to obtain the catalyst.

[0052] The catalyst contains 8.09 wt% TiO2, 7.12 wt% Fe2O3, 3.85 wt% K2O, and the remainder is Al2O3.

[0053] test

[0054] The catalysts prepared according to the embodiments and comparative examples of the present invention were applied to the Claus sulfur recovery reaction in a fixed-bed reactor with a catalyst loading of 10 mL and a gas hourly space velocity of 3000 h⁻¹. -1 The reaction temperature was 250℃. The simulated gas composition (V / V) was: H₂S 2%, SO₂ 1%, O₂ 3400ppm, H₂O 30%, CO₂ 1.0%, CO₂ 2%, with the remainder being N₂. Each catalyst was continuously evaluated for 100 hours, and the average value was taken. The experimental results are shown in Table 1.

[0055] Table 1 Performance Test Results

[0056]

[0057] The above data demonstrate that the Claus reaction activity, organic sulfur hydrolysis activity, and oxygen removal capacity of the catalyst of this invention are all better than those of the catalyst prepared in the comparative example.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sulfur recovery catalyst, characterized in that, The sulfur recovery catalyst uses Al2O3 as a support and is loaded with TiO2, Fe2O3, and A. x O y A is selected from at least one of alkali metals or alkaline earth metals.

2. The sulfur recovery catalyst according to claim 1, characterized in that, A is selected from at least one of Ca, Mg, Ba, Na, and K.

3. The sulfur recovery catalyst according to claim 1, characterized in that, The sulfur recovery catalyst, by mass fraction, contains 1wt%~15wt% TiO2, 0.5wt%~10wt% Fe2O3, and A... x O y The content is 0.1wt%~5wt%, with the remainder being Al2O3.

4. The method for preparing the sulfur recovery catalyst according to claim 1, characterized in that, Includes the following steps: S1 uses oxalic acid, hydrogen peroxide and titanium dioxide to prepare a mixed aqueous solution, and reacts to obtain solution A; S2 prepares aqueous solution B using complexed iron salt and salt containing A; S3. The solution A obtained in step S1 and the aqueous solution B obtained in step S2 are mixed to obtain a Ti-Fe-A composite complex solution, which is then impregnated with an Al2O3 support and calcined to obtain the sulfur recovery catalyst.

5. The preparation method according to claim 4, characterized in that, In step S1, the molar ratio of TiO2, H2C2O4, H2O2, and H2O is 1:(1~3):(2~5):(10~100).

6. The preparation method according to claim 4, characterized in that, In step S1, the reaction temperature is 20~90℃ and the reaction time is 1~20h.

7. The preparation method according to claim 4, characterized in that, In step S2, the complexed iron salt is selected from at least one of EDTA ferric ammonium, EDTA ferric sodium, and ferric citrate; the salt containing A is selected from at least one of soluble salts.

8. The preparation method according to claim 4, characterized in that, In step S3, the calcination temperature is 400~700℃ and the time is 1~20h.

9. The preparation method according to claim 4, characterized in that, In step S2, the molar ratio of complexed iron salt, salt containing A, and H2O is 1:(0.25~5):(10~50).

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