A hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas and a preparation method thereof

Abstract

The application discloses a hydrolysis catalyst for removing carbonyl sulfur in flexible coking gas and a preparation method thereof, and belongs to the technical field of catalysts. The preparation method of the hydrolysis catalyst for removing carbonyl sulfur in flexible coking gas comprises four steps of preparing indium and cerium doped magnesium-aluminum hydrotalcite, surface modification, molding and sintering. The prepared hydrolysis catalyst for removing carbonyl sulfur in flexible coking gas has a carbonyl sulfur hydrolysis conversion rate of 98.1-99.9%.

Description

Technical Field

[0001] This invention relates to a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas and its preparation method, belonging to the field of catalyst technology. Background Technology

[0002] Flexible coking is a new process capable of processing various low-quality oil feedstocks such as residual oil, heavy sludge, waste asphalt, oil sands, and waste lubricating oil. One of its most significant advantages is its high adaptability to feedstocks, allowing it to process various heavy oils with high sulfur, high metal, and high residual carbon content. However, precisely because of the large fluctuations and inconsistent quality of feedstocks, and the fact that most feedstocks have high sulfur content, the fuel gas produced by flexible coking, i.e., flexible coking gas, has a relatively high carbonyl sulfide (COS) content. Carbonyl sulfide not only corrodes pipelines and equipment but can also poison downstream catalysts; therefore, the purification and desulfurization of flexible coking gas is crucial.

[0003] Methods for removing carbonyl sulfide mainly include adsorption, oxidation, hydroconversion, and catalytic hydrolysis. Among these, catalytic hydrolysis offers advantages such as high catalytic efficiency, low reaction temperature, and fewer side reactions, converting carbonyl sulfide into easily removable H₂S. Catalysts used for carbonyl sulfide hydrolysis are mainly of two types: non-metallic oxide catalysts and metal oxide catalysts. Non-metallic oxide catalysts are primarily activated carbon-based catalysts, possessing high porosity and large surface area. However, due to the easy covering of active sites by carbonyl sulfide during the hydrolysis reaction, rapid deactivation occurs, resulting in low sulfur capacity. Metal oxide catalysts mainly include low-temperature, high-activity, and high-sulfur-capacity catalysts with Al2O3 and TiO2 as supports and alkali metal or alkaline earth metal compounds as active components. However, these catalysts have problems such as high hydrolysis reaction temperature and narrow temperature range, low feed gas space velocity, and easy sulfation and poisoning of the catalyst surface when oxygen and sulfur dioxide are present in the feed gas. Therefore, there is an urgent need to develop a carbonyl sulfur hydrolysis catalyst with low hydrolysis temperature, good resistance to sulfur poisoning, and adaptability to high feed gas space velocity operating conditions.

[0004] Chinese patent CN118594598A discloses a flexible coking gas carbonyl sulfide hydrolysis catalyst and its preparation method. It describes the preparation of alumina-doped mesoporous carbon molecular sieves as catalyst supports and the use of a sol-gel method to load metal oxides as active components, thereby producing a highly stable carbonyl sulfide hydrolysis catalyst. However, the active component of the carbonyl sulfide hydrolysis catalyst prepared in this invention is supported on a mesoporous carbon molecular sieve. This structure is difficult to apply under high space velocity operating conditions because the active component supported on the support is easily detached under high gas flow scouring. Furthermore, the hydrolysis reaction temperature for removing carbonyl sulfide using this catalyst is relatively high (80°C), and the corresponding space velocity operating condition is relatively low (1200 h⁻¹). -1 .

[0005] Chinese patent CN104667926A discloses a low-temperature carbonyl sulfide hydrolysis catalyst and its preparation method, using modified γ-FeOOH as the active component. The modified γ-FeOOH catalyst is prepared by the following method: ferrous salt and a modifier are mixed uniformly to form a solution; a precipitant is added dropwise to the solution under stirring; the pH is adjusted to 6.5-8; after aging, centrifugation, and washing with water, a forming agent and a binder are added and kneaded; the mixture is then shaped and dried to obtain the product. The molar ratio of the modifier to the ferric salt in the modified γ-FeOOH is controlled to be 0.005-0.1, with an optimal molar ratio of 0.01-0.05. The low-temperature carbonyl sulfide hydrolysis catalyst obtained by this patent does not exhibit a high carbonyl sulfide removal rate in the low-temperature range of 30-60℃, reaching a maximum of only 96.8%, and the operating space velocity is relatively low, only 1000 h⁻¹. -1 .

[0006] As can be seen above, carbonyl sulfur hydrolysis catalysts still have significant drawbacks such as high hydrolysis reaction temperature and narrow temperature range, low feed gas space velocity and poor resistance to sulfur poisoning. Therefore, there is an urgent need for a carbonyl sulfur hydrolysis catalyst with low hydrolysis temperature, good resistance to sulfur poisoning and adaptability to high feed gas space velocity operating conditions. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas and its preparation method, achieving the following objective: to prepare a carbonyl sulfur hydrolysis catalyst with low hydrolysis temperature, good resistance to sulfur poisoning, and adaptability to high space velocity operating conditions of the feed gas.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas and its preparation method are disclosed. The hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas has a carbonyl sulfur hydrolysis conversion rate of 98.1% to 99.9%.

[0010] The preparation method of the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas includes four steps: preparation of indium cerium-doped magnesium aluminum hydrotalcite, surface modification, molding, and sintering.

[0011] The following are further improvements to the above technical solution:

[0012] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0013] Aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water are mixed and dissolved completely to obtain a mixed salt solution. Sodium hydroxide, sodium carbonate, and deionized water are then mixed and dissolved completely to obtain an alkaline solution. Deionized water is added to a precipitation vessel, and the mixed salt solution and alkaline solution are added dropwise to the vessel while continuously stirring. The dropwise rate of the mixed salt solution and alkaline solution is controlled to maintain the pH value in the precipitation vessel at 10-11. After the dropwise addition is complete, stirring continues until the co-precipitation reaction is complete. The solution is then aged, filtered, washed with water, dried, and calcined to obtain indium-cerium-doped magnesium-aluminum hydrotalcite.

[0014] In the mixed salt solution, the mass ratio of aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water is 20~70:10~50:2~7:1~2.5:260~480;

[0015] In the alkaline solution, the mass ratio of sodium hydroxide, sodium carbonate, and deionized water is 10~45:2~9:150~340;

[0016] In the precipitation vessel, the mass ratio of deionized water, mixed salt solution and alkaline solution is 90~160:50~90:30~65.

[0017] The continuous stirring is carried out at a stirring rate of 400-850 rpm.

[0018] Continue stirring until the co-precipitation reaction is complete, with a reaction time of 2 to 4.5 hours;

[0019] The aging process involves: allowing the liquid obtained from the complete co-precipitation reaction to stand at room temperature for 12-20 hours.

[0020] The water washing process involves washing the filtered solid with deionized water until the pH of the washing solution is 7-7.5.

[0021] The drying process involves a drying temperature of 70-95℃ and a drying time of 13-20 hours.

[0022] The roasting process involves roasting the dried solid at 400-500°C for 4-5.5 hours.

[0023] Step 2, Surface Modification

[0024] Indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier were added to a reaction vessel. The mixture was heated and kept at 50-70°C under sealed conditions. After stirring for 3-6.5 hours, the mixture was cooled to room temperature, discharged, filtered, washed with water, and dried to obtain surface-modified indium-cerium doped magnesium-aluminum hydrotalcite.

[0025] The composite modifier is composed of hydrazine and quaternary ammonium base;

[0026] The quaternary ammonium base is one or a mixture of two or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and hexamethyldiammonium hydroxide in any mass ratio;

[0027] In the composite modifier, the mass ratio of hydrazine to quaternary ammonium base is 3~19:49;

[0028] The mass ratio of the indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier is 40~90:220~440:15~45;

[0029] The stirring reaction is carried out at a stirring rate of 400~1000 rpm;

[0030] The water washing involves washing the solid with deionized water until the pH of the washing solution is 7-7.5;

[0031] The drying process involves a drying temperature of 70-90℃ and a drying time of 16-28 hours.

[0032] Step 3, Shaping

[0033] Surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water were added to a double planetary mixer. The stirring speed was controlled at 90-140 rpm and the dispersion speed at 8000-10000 rpm. After stirring and dispersing for 3-6 hours, a paste-like slurry was obtained. The paste-like slurry was then injected into an extruder to extrude long strip-shaped particles. After drying, the original hydrolysis catalyst particles were obtained.

[0034] The aluminum sol has a solid content of 20-40 wt% and a particle size of 10-100 nm.

[0035] The water-insoluble oxalate is one or more of calcium oxalate, aluminum oxalate, copper oxalate, molybdenum oxalate, and cobalt oxalate in any mass ratio.

[0036] The water-insoluble oxalate is in powder form with a particle size of 0.01~1μm;

[0037] The mass ratio of the surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water is 90~150:20~60:10~33:4~12:20~50.

[0038] The elongated particles have a cross-sectional diameter of 3-5.5 mm and a length of 6-17 mm.

[0039] The drying process involves a drying temperature of 85-97°C and a drying time of 20-36 hours.

[0040] Step 4, Sintering

[0041] The original hydrolysis catalyst particles were placed in a muffle furnace and heated from room temperature to 450-650°C at a heating rate of 1-4°C / min. After constant-temperature calcination for 5-8 hours, the material was naturally cooled to room temperature and discharged to obtain a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas.

[0042] Compared with the prior art, the present invention achieves the following beneficial effects:

[0043] 1. The hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas prepared in this invention uses indium-cerium-doped magnesium-aluminum hydrotalcite as the main active component. The two metal elements, indium and cerium, can form a solid solution during the calcination process. The surface of this oxide solid solution structure can simultaneously provide a large number of oxygen vacancies and basic sites, thereby giving the catalyst very high catalytic activity. Therefore, it can significantly improve the hydrolysis conversion rate of carbonyl sulfur.

[0044] 2. In this invention, a composite modifier composed of hydrazine and quaternary ammonium base is used to modify the surface of indium cerium-doped magnesium aluminum layered double hydroxide. Hydrazine and quaternary ammonium base can undergo alkaline etching reaction with the metal elements on the surface of indium cerium-doped magnesium aluminum layered double hydroxide. This reaction can not only increase the surface area of ​​indium cerium-doped magnesium aluminum layered double hydroxide, but also increase the alkaline sites on the surface of indium cerium-doped magnesium aluminum layered double hydroxide, thus significantly improving the catalytic activity of carbonyl sulfur hydrolysis catalyst.

[0045] 3. This invention increases the specific surface area of ​​the catalyst by adding water-insoluble oxalates. Water-insoluble oxalates act as pore-forming agents. During sintering, water-insoluble oxalates can slowly decompose to generate many micropores inside the catalyst. These micropores greatly increase the specific surface area inside the catalyst, thereby greatly increasing the active sites for catalytic reactions and ultimately improving the catalytic reaction efficiency. In addition, the corresponding oxides formed after the thermal decomposition of these oxalates, such as calcium oxalate, aluminum oxalate, copper oxalate, molybdenum oxalate, and cobalt oxalate, such as calcium oxide, aluminum oxide, copper oxide, molybdenum oxide, and cobalt oxide, also have carbonyl sulfide hydrolysis catalytic ability. Therefore, water-insoluble oxalates have the dual function of pore-forming and improving catalytic activity.

[0046] 4. This invention improves the catalyst's resistance to sulfur poisoning by adding nano-zinc aluminate. Nano-zinc aluminate has a very large specific surface area, and the aluminate ion is highly basic. Zinc ions also readily attach to sulfur, which promotes the affinity of nano-zinc aluminate for hydrogen sulfide and sulfur dioxide. This prevents the active sites of the carbonyl sulfur hydrolysis reaction from being over-occupied by hydrogen sulfide and sulfur dioxide, ultimately enhancing the catalyst's activity in carbonyl sulfur hydrolysis.

[0047] 5. The hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas obtained by the present invention has a carbonyl sulfur hydrolysis conversion rate of 98.1~99.9%. Attached Figure Description

[0048] Figure 1 The image shows a scanning electron microscope image with a cross-sectional magnification of 20,000 for the hydrolysis catalyst obtained in Example 1 for removing carbonyl sulfur from flexible coking gas.

[0049] Figure 2 The image shown is a scanning electron microscope (SEM) image with a cross-sectional magnification of 20,000 for the hydrolysis catalyst obtained in Example 2 for removing carbonyl sulfur from flexible coking gas. Detailed Implementation

[0050] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0051] Example 1: A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas

[0052] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0053] Aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water are mixed and dissolved completely to obtain a mixed salt solution. Sodium hydroxide, sodium carbonate, and deionized water are then mixed and dissolved completely to obtain an alkaline solution. Deionized water is added to a precipitation vessel, and the mixed salt solution and alkaline solution are added dropwise to the vessel while continuously stirring. The dropwise rate of the mixed salt solution and alkaline solution is controlled to maintain the pH value in the precipitation vessel at 10.6. After the dropwise addition is complete, stirring continues until the co-precipitation reaction is complete. The solution is then aged, filtered, washed with water, dried, and calcined to obtain indium-cerium-doped magnesium-aluminum hydrotalcite.

[0054] In the mixed salt solution, the mass ratio of aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water is 40:30:5:2:350.

[0055] In the alkaline solution, the mass ratio of sodium hydroxide, sodium carbonate, and deionized water is 25:6:260.

[0056] In the precipitation vessel, the mass ratio of deionized water, mixed salt solution and alkaline solution is 110:80:50.

[0057] The continuous stirring is performed at a stirring rate of 650 rpm.

[0058] Continue stirring until the co-precipitation reaction is complete, with a reaction time of 3.5 hours;

[0059] The aging process is as follows: the liquid obtained after the complete co-precipitation reaction is allowed to stand at room temperature for 17 hours.

[0060] The water washing involves washing the filtered solid with deionized water until the pH of the washing solution is 7.2.

[0061] The drying process is carried out at a temperature of 85°C for 16 hours.

[0062] The roasting process involves roasting the dried solid at 460°C for 5 hours.

[0063] Step 2, Surface Modification

[0064] Indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier were added to a reaction vessel. The temperature was raised and kept constant at 58°C under sealed conditions. After stirring and reacting for 5 hours, the temperature was lowered to room temperature, the material was discharged and filtered, and then washed with water and dried to obtain surface-modified indium-cerium doped magnesium-aluminum hydrotalcite.

[0065] The composite modifier is composed of hydrazine and quaternary ammonium base;

[0066] The quaternary ammonium base is tetramethylammonium hydroxide;

[0067] In the composite modifier, the mass ratio of hydrazine to quaternary ammonium base is 11:49;

[0068] The mass ratio of the indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier is 60:340:30.

[0069] The stirring reaction was carried out at a stirring rate of 600 rpm.

[0070] The water washing involves washing the solid with deionized water until the pH of the washing solution is 7.2.

[0071] The drying process is carried out at a temperature of 80°C for 22 hours.

[0072] Step 3, Shaping

[0073] Surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water were added to a double planetary mixer. The stirring speed was controlled at 120 rpm and the dispersion rate at 9000 rpm. After stirring and dispersing for 4 hours, a paste-like slurry was obtained. The paste-like slurry was then injected into an extruder to extrude long strip-shaped particles. After drying, the original hydrolysis catalyst particles were obtained.

[0074] The aluminum sol has a solid content of 35 wt% and a particle size of 40 nm.

[0075] The oxalate that is sparingly soluble in water is calcium oxalate;

[0076] The water-insoluble oxalate is in powder form with a particle size of 0.4 μm;

[0077] The mass ratio of the surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water is 120:50:23:9:30.

[0078] The elongated granules have a cross-sectional diameter of 5 mm and a length of 13 mm.

[0079] The drying process was carried out at a temperature of 89°C for 26 hours.

[0080] Step 4, Sintering

[0081] The original hydrolysis catalyst particles were placed in a muffle furnace and heated from room temperature to 550°C at a heating rate of 3°C / min. After being calcined at a constant temperature for 7 hours, the mixture was naturally cooled to room temperature, and the resulting material was discharged to obtain a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas.

[0082] Example 2: A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas

[0083] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0084] Aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water are mixed and dissolved completely to obtain a mixed salt solution. Sodium hydroxide, sodium carbonate, and deionized water are then mixed and dissolved completely to obtain an alkaline solution. Deionized water is added to a precipitation vessel, and the mixed salt solution and alkaline solution are added dropwise to the vessel while continuously stirring. The dropwise rate of the mixed salt solution and alkaline solution is controlled to maintain the pH value in the precipitation vessel at 10. After the dropwise addition is complete, stirring continues until the co-precipitation reaction is complete. The solution is then aged, filtered, washed with water, dried, and calcined to obtain indium-cerium-doped magnesium-aluminum hydrotalcite.

[0085] In the mixed salt solution, the mass ratio of aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water is 20:10:2:1:260.

[0086] In the alkaline solution, the mass ratio of sodium hydroxide, sodium carbonate, and deionized water is 10:2:150.

[0087] In the precipitation vessel, the mass ratio of deionized water, mixed salt solution and alkaline solution is 90:50:30.

[0088] The continuous stirring is carried out at a stirring rate of 400 rpm.

[0089] Continue stirring until the co-precipitation reaction is complete, with a reaction time of 2 hours;

[0090] The aging process is as follows: the liquid obtained after the complete co-precipitation reaction is allowed to stand at room temperature for 12 hours.

[0091] The water washing involves washing the filtered solid with deionized water until the pH of the washing solution is 7.

[0092] The drying process is carried out at a temperature of 70°C for 13 hours.

[0093] The roasting process involves roasting the dried solid at 400°C for 4 hours.

[0094] Step 2, Surface Modification

[0095] Indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier were added to a reaction vessel. The mixture was heated and kept at 50°C under sealed conditions. After stirring and reacting for 3 hours, the mixture was cooled to room temperature, discharged, filtered, washed with water, and dried to obtain surface-modified indium-cerium doped magnesium-aluminum hydrotalcite.

[0096] The composite modifier is composed of hydrazine and quaternary ammonium base;

[0097] The quaternary ammonium base is tetraethylammonium hydroxide;

[0098] In the composite modifier, the mass ratio of hydrazine to quaternary ammonium base is 3:49;

[0099] The mass ratio of the indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier is 40:220:15.

[0100] The stirring reaction was carried out at a stirring rate of 400 rpm.

[0101] The water washing involves washing the solid with deionized water until the pH of the washing solution is 7.

[0102] The drying process is carried out at a temperature of 70°C for 16 hours.

[0103] Step 3, Shaping

[0104] Surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water were added to a double planetary mixer. The stirring speed was controlled at 90 rpm and the dispersion speed at 8000 rpm. After stirring and dispersing for 3 hours, a paste slurry was obtained. The paste slurry was then injected into an extruder to extrude long strip particles. After drying, the original hydrolysis catalyst particles were obtained.

[0105] The aluminum sol has a solid content of 20 wt% and a particle size of 10 nm.

[0106] The oxalate that is sparingly soluble in water is aluminum oxalate;

[0107] The water-insoluble oxalate is in powder form with a particle size of 0.01 μm;

[0108] The mass ratio of the surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water is 90:20:10:4:20.

[0109] The elongated granules have a cross-sectional diameter of 3 mm and a length of 6 mm.

[0110] The drying process involves a drying temperature of 85°C and a drying time of 20 hours.

[0111] Step 4, Sintering

[0112] The original hydrolysis catalyst particles were placed in a muffle furnace and heated from room temperature to 450°C at a heating rate of 1°C / min. After being calcined at a constant temperature for 5 hours, the mixture was naturally cooled to room temperature, and the resulting material was discharged to obtain a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas.

[0113] Example 3: A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas

[0114] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0115] Aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water are mixed and dissolved completely to obtain a mixed salt solution. Sodium hydroxide, sodium carbonate, and deionized water are then mixed and dissolved completely to obtain an alkaline solution. Deionized water is added to a precipitation vessel, and the mixed salt solution and alkaline solution are added dropwise to the vessel while continuously stirring. The dropwise rate of the mixed salt solution and alkaline solution is controlled to maintain the pH value in the precipitation vessel at 11. After the dropwise addition is complete, stirring continues until the co-precipitation reaction is complete. The solution is then aged, filtered, washed with water, dried, and calcined to obtain indium-cerium-doped magnesium-aluminum hydrotalcite.

[0116] In the mixed salt solution, the mass ratio of aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water is 70:50:7:2.5:480.

[0117] In the alkaline solution, the mass ratio of sodium hydroxide, sodium carbonate, and deionized water is 45:9:340.

[0118] In the precipitation vessel, the mass ratio of deionized water, mixed salt solution and alkaline solution is 160:90:65.

[0119] The continuous stirring is performed at a stirring rate of 850 rpm.

[0120] Continue stirring until the co-precipitation reaction is complete, with a reaction time of 4.5 hours;

[0121] The aging process is as follows: the liquid obtained after the complete co-precipitation reaction is allowed to stand at room temperature for 20 hours.

[0122] The water washing involves washing the filtered solid with deionized water until the pH of the washing solution is 7.5.

[0123] The drying process is carried out at a temperature of 95°C for 20 hours.

[0124] The roasting process involves roasting the dried solid at 500°C for 5.5 hours.

[0125] Step 2, Surface Modification

[0126] Indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier were added to a reaction vessel. The mixture was heated and kept at 70°C under sealed conditions. After stirring and reacting for 6.5 hours, the mixture was cooled to room temperature, discharged, filtered, washed with water, and dried to obtain surface-modified indium-cerium doped magnesium-aluminum hydrotalcite.

[0127] The composite modifier is composed of hydrazine and quaternary ammonium base;

[0128] The quaternary ammonium base is tetrapropylammonium hydroxide;

[0129] In the composite modifier, the mass ratio of hydrazine to quaternary ammonium base is 19:49;

[0130] The mass ratio of the indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier is 90:440:45.

[0131] The stirring reaction was carried out at a stirring rate of 1000 rpm.

[0132] The water washing involves washing the solid with deionized water until the pH of the washing solution is 7.5.

[0133] The drying process is carried out at a temperature of 90°C for 28 hours.

[0134] Step 3, Shaping

[0135] Surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water were added to a double planetary mixer. The stirring speed was controlled at 140 rpm and the dispersion speed at 10,000 rpm. After stirring and dispersing for 6 hours, a paste-like slurry was obtained. The paste-like slurry was then injected into an extruder to extrude long strip-shaped particles. After drying, the original hydrolysis catalyst particles were obtained.

[0136] The aluminum sol has a solid content of 40 wt% and a particle size of 100 nm.

[0137] The water-insoluble oxalate is copper oxalate;

[0138] The water-insoluble oxalate is in powder form with a particle size of 1 μm;

[0139] The mass ratio of the surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water is 150:60:33:12:50.

[0140] The elongated granules have a cross-sectional diameter of 5.5 mm and a length of 17 mm.

[0141] The drying process was carried out at a temperature of 97°C for 36 hours.

[0142] Step 4, Sintering

[0143] The original hydrolysis catalyst particles were placed in a muffle furnace and heated from room temperature to 650°C at a heating rate of 4°C / min. After being calcined at a constant temperature for 8 hours, the mixture was naturally cooled to room temperature and discharged to obtain a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas.

[0144] Example 4: A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas

[0145] Step 1 is the same as in Example 1;

[0146] Step 2, Surface Modification

[0147] The quaternary ammonium base is tetrabutylammonium hydroxide, and the other operations are the same as in Example 1;

[0148] Step 3, Shaping

[0149] The water-insoluble oxalate is molybdenum oxalate, and the other operations are the same as in Example 1;

[0150] Step 4 is the same as in Example 1.

[0151] Example 5: A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas

[0152] Step 1 is the same as in Example 1;

[0153] Step 2, Surface Modification

[0154] The quaternary ammonium base is hexamethyldiammonium hydroxide, and the other operations are the same as in Example 1;

[0155] Step 3, Shaping

[0156] The water-insoluble oxalate is cobalt oxalate, and the other operations are the same as in Example 1;

[0157] Step 4 is the same as in Example 1.

[0158] Comparative Example 1: Based on Example 1, in step 1, the preparation of indium-cerium-doped magnesium-aluminum hydrotalcite, indium nitrate and cerium nitrate were not added. Instead, 5 parts of indium nitrate and 2 parts of cerium nitrate were replaced with 7 parts of deionized water. The specific operation is as follows:

[0159] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0160] Replace 5 parts indium nitrate and 2 parts cerium nitrate with 7 parts deionized water, and perform the other operations as in Example 1;

[0161] Steps 2, 3, and 4 are the same as in Example 1.

[0162] Comparative Example 2: Based on Example 1, in step 1, the preparation of indium-cerium-doped magnesium-aluminum hydrotalcite, indium nitrate was not added, and 5 parts of indium nitrate were replaced with 5 parts of deionized water in equal amounts. The specific operation is as follows:

[0163] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0164] Replace 5 parts of indium nitrate with 5 parts of deionized water, and perform the other operations as in Example 1;

[0165] Steps 2, 3, and 4 are the same as in Example 1.

[0166] Comparative Example 3: Based on Example 1, in step 1, the preparation of indium-cerium-doped magnesium-aluminum hydrotalcite, cerium nitrate was not added, and 2 parts of cerium nitrate were replaced with 2 parts of deionized water in equal amounts. The specific operation is as follows:

[0167] Step 1: Preparation of indium-cerium-doped magnesium-aluminum hydrotalcite

[0168] Replace 2 parts of cerium nitrate with 2 parts of deionized water, and perform the other operations as in Example 1;

[0169] Steps 2, 3, and 4 are the same as in Example 1.

[0170] Comparative Example 4: Based on Example 1, step 2 and surface modification were omitted. The specific operation is as follows:

[0171] Step 1 is the same as in Example 1;

[0172] Step 2, surface modification, is not performed;

[0173] Step 3, Shaping

[0174] The surface-modified indium cerium-doped magnesium aluminum hydrotalcite was replaced with an equal amount of indium cerium-doped magnesium aluminum hydrotalcite, and other operations were the same as in Example 1;

[0175] Step 4 is the same as in Example 1.

[0176] Comparative Example 5: Based on Example 1, in step 3, during molding, instead of adding water-insoluble oxalate, 23 parts of water-insoluble oxalate were replaced with 23 parts of surface-modified indium cerium-doped magnesium aluminum hydrotalcite. The specific operation is as follows:

[0177] Steps 1 and 2 are the same as in Example 1;

[0178] Step 3, Shaping

[0179] Replace 23 parts of water-insoluble oxalate with 23 parts of surface-modified indium cerium-doped magnesium aluminum hydrotalcite, and perform the other operations as in Example 1.

[0180] Step 4 is the same as in Example 1.

[0181] Comparative Example 6: Based on Example 1, in step 3, during molding, instead of adding nano-zinc aluminate, 9 parts of nano-zinc aluminate were replaced with 9 parts of surface-modified indium cerium-doped magnesium aluminum hydrotalcite. The specific operation is as follows:

[0182] Steps 1 and 2 are the same as in Example 1;

[0183] Step 3, Shaping

[0184] Nine parts of nano zinc aluminate were replaced with nine parts of surface-modified indium cerium-doped magnesium aluminum hydrotalcite, and other operations were the same as in Example 1.

[0185] Step 4 is the same as in Example 1.

[0186] Performance testing:

[0187] The hydrolysis catalysts obtained in Examples 1, 2, 3, 4, 5 and Comparative Examples 1, 2, 3, 4, 5, 6 for removing carbonyl sulfide from flexible coking gas were packed into a fixed-bed reactor. The inlet flue gas contained 1000 ppm carbonyl sulfide, 2 wt% water, 4000 ppm hydrogen sulfide, 6000 ppm sulfur dioxide, and the balance being N2. The reactor was subjected to a space velocity of 5000 h⁻¹. -1 The reaction temperatures were 30℃ and 60℃, and the space velocity was 10000 h⁻¹. -1 Under four reaction conditions (30℃, 60℃), the hydrolysis conversion rate of carbonyl sulfide was analyzed and calculated by gas chromatography to evaluate the performance of the catalyst in removing carbonyl sulfide.

[0188] The test results are shown in Table 1:

[0189] Table 1

[0190]

[0191] As can be seen from the test data in Table 1, Examples 1-5 at an airspeed of 5000 h⁻¹ -1The reaction temperatures were 30℃ and 60℃, and the space velocity was 10000 h⁻¹. -1 Under four reaction conditions (30℃, 60℃), the carbonyl sulfur hydrolysis conversion rate was above 98%. Furthermore, the inlet flue gas used in this invention contained high concentrations of sulfur dioxide and hydrogen sulfide, indicating that the hydrolysis catalyst obtained in this invention for removing carbonyl sulfur from flexible coking gas possesses excellent properties such as low hydrolysis temperature, good resistance to sulfur poisoning, and adaptability to high-space-velocity operation of the feed gas. In Comparative Examples 1, 2, and 3, the carbonyl sulfur hydrolysis conversion rate decreased significantly in Comparative Example 1 (without indium nitrate or cerium nitrate) or with only one of indium nitrate or cerium nitrate. In Comparative Example 2 (with only cerium nitrate) and Comparative Example 3 (with only indium nitrate), the carbonyl sulfur hydrolysis conversion rate decreased significantly. The conversion rates also decreased significantly, indicating that cerium nitrate and indium nitrate have a very good synergistic effect on improving the catalytic activity of the catalyst. This may be because the oxides of cerium and indium can form a solid solution, and the surface of this oxide solid solution structure can simultaneously provide a large number of oxygen vacancies and basic sites, thus giving the catalyst very high catalytic activity and ultimately greatly improving the hydrolysis conversion rate of carbonyl sulfide. In Comparative Example 4, without surface modification of indium-cerium-doped magnesium aluminum layered double hydroxides by the composite modifier composed of hydrazine and quaternary ammonium base, the hydrolysis conversion rate of carbonyl sulfide in Comparative Example 4 was significantly reduced to below 90%. This may be because hydrazine and quaternary ammonium base can react with the metal elements on the surface of indium-cerium-doped magnesium aluminum layered double hydroxides. An alkaline etching reaction occurs, which not only increases the surface area of ​​indium cerium-doped magnesium aluminum layered double hydroxide (ILDH) but also increases the number of alkaline sites on its surface, thus significantly improving the catalytic activity of the carbonyl sulfide hydrolysis catalyst. In Comparative Example 5, without the addition of water-insoluble oxalate, the carbonyl sulfide hydrolysis conversion rate decreased dramatically, reaching the lowest value among all examples and comparative examples. This indicates that water-insoluble oxalate plays a crucial role in the catalyst's catalytic efficiency because it acts as a pore-forming agent. During sintering, the water-insoluble oxalate undergoes slow thermal decomposition, generating numerous micropores within the catalyst. These micropores greatly increase the specific surface area within the catalyst. The addition of nano-zinc aluminate significantly increases the active sites for the catalytic reaction, ultimately improving the catalytic efficiency. In Comparative Example 6, without the addition of nano-zinc aluminate, the carbonyl sulfur hydrolysis conversion rate decreased to below 85.4%. This indicates that nano-zinc aluminate plays a crucial role in maintaining catalyst activity. This may be because nano-zinc aluminate can enhance the catalyst's resistance to sulfur poisoning. Nano-zinc aluminate has a very large specific surface area, and the aluminate ion is highly basic. Zinc ions also readily attach to sulfur, which promotes the affinity of nano-zinc aluminate for hydrogen sulfide and sulfur dioxide. This prevents the active sites for the carbonyl sulfur hydrolysis reaction from being over-occupied by hydrogen sulfide and sulfur dioxide, ultimately enhancing the catalytic activity of the carbonyl sulfur hydrolysis catalyst.

[0192] Appendix Figure 1 Appendix Figure 2 The images shown are scanning electron microscope (SEM) images with a cross-sectional magnification of 20,000, obtained from Examples 1 and 2, respectively, for the hydrolysis catalysts used to remove carbonyl sulfur from flexible coking gas. Both images clearly show the micropores and cavities inside the catalyst, as well as the tiny particles surrounding these micropore structures. These micropores and cavities are formed after the thermal decomposition of oxalate, which is insoluble in water. Moreover, the inner surfaces of the micropores and cavities, as well as the surfaces of the tiny particles, are relatively rough. This may be due to the etching of indium-cerium-doped magnesium-aluminum hydrotalcite by the composite modifier. The micropores, cavities, and rough surfaces clearly visible in these images can significantly increase the specific surface area of ​​the catalyst, thereby improving the catalytic activity and catalytic efficiency of the catalyst.

[0193] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas, characterized in that: The preparation method of the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas includes four steps: preparation of indium cerium-doped magnesium aluminum hydrotalcite, surface modification, molding, and sintering. The preparation of indium-cerium-doped magnesium-aluminum hydrotalcite involves completely dissolving aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water to obtain a mixed salt solution. Then, sodium hydroxide, sodium carbonate, and deionized water are completely dissolved to obtain an alkaline solution. Deionized water is added to a precipitation vessel, and while continuously stirring, the mixed salt solution and alkaline solution are dripped into the vessel. The dripping rate of the mixed salt solution and alkaline solution is controlled to maintain the pH value in the precipitation vessel at 10-11. After the dripping is complete, stirring continues until the co-precipitation reaction is complete. The mixture is then aged, filtered, washed, dried, and calcined to obtain indium-cerium-doped magnesium-aluminum hydrotalcite. The surface modification involves adding indium cerium-doped magnesium aluminum hydrotalcite, deionized water, and a composite modifier into a reaction vessel, heating and maintaining the temperature at 50-70°C under sealed conditions, stirring and reacting for 3-6.5 hours, cooling to room temperature, discharging and filtering, and then washing and drying to obtain surface-modified indium cerium-doped magnesium aluminum hydrotalcite. The composite modifier is composed of hydrazine and quaternary ammonium base; The quaternary ammonium base is one or a mixture of two or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and hexamethyldiammonium hydroxide in any mass ratio; The molding process involves adding surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water into a double planetary mixer. The mixing speed is controlled at 90-140 rpm and the dispersion speed at 8000-10000 rpm. After mixing and dispersing for 3-6 hours, a paste-like slurry is obtained. The paste-like slurry is then injected into an extruder to extrude long strip-shaped particles. After drying, the original hydrolysis catalyst particles are obtained. The water-insoluble oxalate is one or more of calcium oxalate, aluminum oxalate, copper oxalate, molybdenum oxalate, and cobalt oxalate in any mass ratio.

2. The method for preparing the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas according to claim 1, characterized in that: In the mixed salt solution, the mass ratio of aluminum nitrate, magnesium nitrate, indium nitrate, cerium nitrate, and deionized water is 20~70:10~50:2~7:1~2.5:260~480; In the alkaline solution, the mass ratio of sodium hydroxide, sodium carbonate, and deionized water is 10~45:2~9:150~340; In the precipitation vessel, the mass ratio of deionized water, mixed salt solution, and alkaline solution is 90~160:50~90:30~65.

3. The method for preparing the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas according to claim 1, characterized in that: In the composite modifier, the mass ratio of hydrazine to quaternary ammonium base is 3~19:49; The mass ratio of the indium-cerium doped magnesium-aluminum hydrotalcite, deionized water, and composite modifier is 40~90:220~440:15~45.

4. The method for preparing the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas according to claim 1, characterized in that: The aluminum sol has a solid content of 20-40 wt% and a particle size of 10-100 nm. The water-insoluble oxalate is in powder form with a particle size of 0.01~1μm.

5. The method for preparing the hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas according to claim 1, characterized in that: The mass ratio of the surface-modified indium cerium-doped magnesium aluminum hydrotalcite, aluminum sol, water-insoluble oxalate, nano zinc aluminate, and deionized water is 90~150:20~60:10~33:4~12:20~50. The elongated particles have a cross-sectional diameter of 3-5.5 mm and a length of 6-17 mm.

6. A hydrolysis catalyst for removing carbonyl sulfur from flexible coking gas prepared by any one of the preparation methods according to claims 1-5.

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