Catalyst and its application and method for removing carbonyl sulfide from natural gas

Abstract

The present invention belongs to the field of desulfurization technology, and specifically relates to a catalyst and its application and a method for removing carbonyl sulfide from natural gas. The catalyst comprises: a carrier, an alkali metal oxide and nickel oxide supported on the carrier; wherein, based on the total weight of the catalyst, the content of the carrier is 90-97wt%, the content of the alkali metal oxide is 2-6wt%, and the content of the nickel oxide is 1-4wt%; and at least part of the carrier is AlO(OH), χ-Al2O3, and η-Al2O3 phases. The catalyst has the advantages of high catalytic activity, good activity stability, and long service life. It can achieve a COS conversion rate of ≥99% and a service life of more than 8 years, effectively reducing the carbonyl sulfide content in natural gas.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202111250608.6, filed on October 26, 2021, entitled “COS conversion catalyst, preparation method and method for recovering sulfur from natural gas”, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention belongs to the technical field of desulfurization, and in particular relates to a catalyst and its application and a method for removing carbonyl sulfide from natural gas. Background Art

[0004] As a high-quality, efficient and clean fossil energy, natural gas accounts for about 25% of the world's primary energy consumption structure and has become an important energy source. In recent years, a number of new high-sulfur large-scale gas fields have been developed in my country, which has put forward new requirements for natural gas purification technology. The newly implemented national standard GB17820-2018 "Natural Gas" stipulates that the total sulfur content (measured in sulfur) of Class I gas is ≤20mg / m 3 , hydrogen sulfide content ≤6mg / m 3 , which puts higher demands on natural gas desulfurization technology.

[0005] Due to the high content of organic sulfur (primarily COS) in natural gas, a separate COS hydrolysis unit is typically installed before the Claus unit. Sinopec's Puguang Natural Gas Purification Plant installed a COS hydrolysis unit upstream of the sulfur recovery unit to reduce the organic sulfur content in natural gas. Natural gas contains a certain amount of carbon dioxide, which inhibits the COS hydrolysis reaction. This requires a high activity of the COS conversion catalyst in the natural gas sulfur recovery unit to meet desulfurization requirements.

[0006] CN1069673A discloses a room-temperature organic sulfur hydrolysis catalyst, which is composed of a potassium-containing compound and a carrier, wherein the carrier contains 2%-25% of K2CO3 by weight. The carrier is spherical γ-Al2O3 and must meet the following requirements: spherical diameter 2-8mm; water absorption rate 0.35-0.65mL / g; specific surface area 150-350m 2 / g; mechanical strength ≥30N / granule. The COS conversion rate of this catalyst is not high, and the COS content and space velocity of the processed raw gas are relatively low, respectively 1-5mg / m 3 and 2000h -1 .

[0007] USP4511668 discloses a COS hydrolysis catalyst using TiO2 as a carrier and containing at least one alkali metal, alkaline earth metal, Group IIB metal, and Group IVA metal as an active component. This catalyst also has a low COS conversion rate and a high reaction temperature (200-400°C). In addition, the use of titanium oxide as a carrier results in a high preparation cost and high catalyst attrition.

[0008] It can be seen that the COS conversion rate of the catalyst in the existing technology is not ideal and the desulfurization effect is average. It is urgent to develop a new organic sulfur conversion catalyst to solve the above problems. Summary of the Invention

[0009] The present invention aims to provide a catalyst, preparation method and application thereof to address the problems of existing organic sulfur conversion catalysts, such as unsatisfactory catalytic activity and COS conversion rate, high reaction temperature and poor activity stability.

[0010] To achieve the above-mentioned object, the first aspect of the present invention provides a catalyst comprising: a carrier, an alkali metal oxide and nickel oxide supported on the carrier; wherein, based on the total weight of the catalyst, the content of the carrier is 90-97wt%, the content of the alkali metal oxide is 2-6wt%, and the content of the nickel oxide is 1-4wt%; and at least a portion of the carrier is AlO(OH), χ-Al2O3 and η-Al2O3 phases.

[0011] The second aspect of the present invention provides use of the catalyst described in the first aspect in removing carbonyl sulfide.

[0012] The third aspect of the present invention provides a method for removing carbonyl sulfide from natural gas, comprising: contacting raw natural gas with a desulfurizing agent to react and separate to obtain product natural gas and H2S; wherein,

[0013] The desulfurizing agent is the catalyst described in the first aspect above;

[0014] The reaction conditions include: the volume space velocity of the raw natural gas is 1000-5000h -1 , the reaction temperature is 100-140℃.

[0015] Through the above technical solution, the present invention has the following beneficial effects:

[0016] (1) The catalyst provided by the present invention has the advantages of high catalytic activity, good activity stability, long service life, and low reaction temperature. It can achieve a COS conversion rate of ≥99%, an operating temperature of 100-140°C, and a service life of more than 8 years. In contrast, the COS conversion rate of catalysts in the prior art is generally no higher than 99%, and the service life does not exceed 6 years.

[0017] (2) It can be used in the organic sulfur conversion unit of natural gas purification plants, which can significantly improve the organic sulfur conversion rate of the unit and effectively reduce the total sulfur content in the product natural gas;

[0018] (3) The preparation process is simple and there is no secondary pollution during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 is the XRD pattern of the catalyst prepared in Example 1 of the present invention.

[0021] Figure 2 This is a pore size distribution test chart (mercury intrusion method) of the catalyst prepared in Example 1 of the present invention.

[0022] Figure 3 This is a pore size distribution test chart (mercury intrusion method) of the catalyst prepared in Comparative Example 6 of the present invention.

[0023] Figure 4 1 is a process flow chart of the COS conversion test in an embodiment of the present invention.

[0024] Description of Reference Numerals

[0025] 1. CH4, C2H6 gas cylinders 2. H2 gas cylinders

[0026] 3. H2S gas cylinder 4. Methyl mercaptan gas cylinder

[0027] 5. COS cylinder 6. CO2 cylinder

[0028] 7. Water bottle 8. Mass flow meter

[0029] 9. Pump 10. Buffer tank

[0030] 11. Reactor 12. Sulfur Accumulator

[0031] 13. Cold trap 14. Alkali washing tank

[0032] 15. Chromatography 16. Exhaust DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0035] A first aspect of the present invention provides a catalyst comprising: a carrier, an alkali metal oxide and nickel oxide supported on the carrier; wherein, based on the total weight of the catalyst, the content of the carrier is 90-97wt%, the content of the alkali metal oxide is 2-6wt%, and the content of the nickel oxide is 1-4wt%; and at least a portion of the carrier is AlO(OH), χ-Al2O3 and η-Al2O3 phases.

[0036] According to the present invention, on the basis of satisfying the above-mentioned quantitative relationship, in order to obtain better catalytic activity, activity stability and service life, preferably, based on the total weight of the catalyst, the content of the carrier can be 93-95wt%, the content of the alkali metal oxide can be 3-4wt%, and the content of nickel oxide can be 2-3wt%.

[0037] According to the present invention, alkali metal oxide and nickel oxide are simultaneously loaded on the support of the catalyst, wherein the alkali metal oxide is preferably sodium oxide and / or potassium oxide.

[0038] According to the present invention, in the catalyst, the content of alkali metal oxide is preferably higher than that of nickel oxide. Preferably, the content of alkali metal oxide is 0.5-3 wt % higher than that of nickel oxide.

[0039] According to the present invention, the catalyst has a specific phase composition. Specifically, the specific phase of the catalyst is derived from the carrier contained in the catalyst, at least part of the carrier is AlO(OH), χ-Al2O3 and η-Al2O3 phases. In the XRD test spectrum of the catalyst, characteristic diffraction peaks of AlO(OH) appear at 2θ of 14.44°, 28.24°, 38.24° and 48.80°, and characteristic diffraction peaks of AlO(OH) appear at 2θ of 37.31°, 45 Characteristic diffraction peaks of η-Al2O3 appear at 2θ of 37.31°, 42.41°, 45.56° and 67.50°, characteristic diffraction peaks of χ-Al2O3 appear at 2θ of 37.80°, 45.90° and 67.00°, and no characteristic diffraction peaks of γ-Al2O3 are observed at 2θ of 37.80°, 45.90° and 67.00°, indicating that the catalyst contains AlO(OH), χ-Al2O3 and η-Al2O3 phases, but substantially does not contain γ-Al2O3. In the catalyst carrier, the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 is 1:(2-5):(0.2-0.6), preferably 1:(3-4):(0.4-0.5).

[0040] According to the present invention, in the catalyst, based on the total weight of the catalyst, the content of γ-Al2O3 does not exceed 0.5wt%, and the total content of AlO(OH), χ-Al2O3 and η-Al2O3 is not less than 90wt%.

[0041] In the present invention, the contents of AlO(OH), χ-Al2O3, and η-Al2O3 are calculated by the peak areas of the above-mentioned characteristic diffraction peaks.

[0042] According to the present invention, the catalyst has the above-mentioned specific phase composition and phase content, which is conducive to obtaining better catalytic activity, activity stability and service life.

[0043] According to the present invention, the catalyst has a high specific surface area and a large pore volume. Preferably, the specific surface area of the catalyst is greater than 300 m 2 / g, and a pore volume greater than 0.45mL / g, which can promote better catalytic activity, good activity stability and service life.

[0044] In the present invention, the specific surface area is measured by nitrogen adsorption method, and the pore volume is measured by mercury intrusion method.

[0045] According to the present invention, the catalyst has a relatively high weak basic center content. Preferably, the weak basic center content of the catalyst is 2.15-2.3 mmolCO2 / g catalyst, which can bring about better catalytic activity.

[0046] In the present invention, the weak basic center content is determined by measuring the amount of CO2 with a desorption temperature below 200° C. in a CO2-TPD spectrum obtained by testing the catalyst using a carbon dioxide temperature-programmed desorption method (CO2-TPD).

[0047] According to the present invention, the catalyst exhibits a bimodal pore size distribution in its pore structure, as measured by mercury intrusion porosimetry, with peaks located in the 1000-4000 nm and 4-20 nm ranges, respectively. Furthermore, the catalyst exhibits a high macropore content. In its pore structure, as measured by mercury intrusion porosimetry, the total volume of pores with a diameter greater than 75 nm accounts for at least 35% by volume of the total pore volume of the catalyst, thereby contributing to improved catalytic activity, excellent activity stability, and a longer service life.

[0048] In the present invention, the proportion of the sum of the volume of pores with a pore diameter greater than 75 nm is obtained by summing the volume of pores with a pore diameter greater than 75 nm in the pore structure data obtained by mercury intrusion porosimetry and dividing it by the total volume of all pores.

[0049] According to the present invention, preferably, in the pore structure of the catalyst measured by mercury intrusion porosimetry, based on the total pore volume of the catalyst, the sum of the volume of pores with a pore diameter greater than 75 nm accounts for 35-60% by volume.

[0050] In the present invention, the catalyst provided herein, when containing the aforementioned specific amounts of alkali metal oxide and nickel oxide, and a carrier composed of a specific phase, can produce a synergistic effect, resulting in significantly improved catalyst performance, characterized by high catalytic activity, good activity stability, long service life, and low reaction temperature. It can achieve a COS conversion rate of ≥ 99%, thereby significantly reducing the total sulfur content in natural gas. Outside of the aforementioned limited range, the resulting catalyst will not possess the comprehensive performance of the catalyst provided herein in terms of catalytic activity, activity stability, and service life.

[0051] According to the present invention, the catalyst carrier is prepared by rapidly de-powdering aluminum hydroxide, then loaded with alkali metal salts and nickel salts, and finally calcined to obtain the catalyst. Preferably, the catalyst provided by the present invention can be prepared by the following method, comprising:

[0052] (1) mixing aluminum hydroxide with a pore-enlarging agent to form a solid material;

[0053] (2) forming the solid material and a solution containing a binder, and sequentially aging, drying, and calcining the formed product to obtain a carrier;

[0054] (3) The carrier is loaded with alkali metal salt and nickel salt, and then dried and calcined in sequence to obtain a catalyst.

[0055] According to the present invention, in step (1), preferably, the specific surface area of the aluminum hydroxide that is quickly de-powdered is greater than 250m 2 / g, pore volume greater than 0.25mL / g; further preferably, the specific surface area is greater than 300m 2 / g, and the pore volume is as large as 0.35mL / g, which is conducive to obtaining better support performance and catalyst activity.

[0056] According to the present invention, in step (1), the pore-enlarging agent can be selected from sesbania powder, methylcellulose or starch, preferably sesbania powder. During the subsequent calcination process to prepare the carrier, the pore-enlarging agent will be completely decomposed, and it can be considered that the final catalyst does not contain the pore-enlarging agent.

[0057] According to the present invention, in step (1), the amount of the aluminum hydroxide powder is such that the content of the carrier is 90-97 wt%, preferably 93-95 wt%, based on the total weight of the catalyst. The amount of the pore-enlarging agent is 1-5 wt%, preferably 2-4 wt%, based on the total weight of the catalyst.

[0058] According to the present invention, in step (1), the present invention has no special limitation on the mixing, as long as the aluminum hydroxide quick-de-powdering agent can be evenly mixed with the pore-enlarging agent to obtain a uniform solid material that meets the molding process requirements.

[0059] According to the present invention, in step (2), the solution containing the binder can be used as long as it can effectively bond the particles of the solid material and enable molding. Preferably, an aqueous solution of the binder can be used. The present invention does not particularly limit the concentration of the binder in the solution, and it can be adjusted and selected according to the needs of the molding process. The binder can be selected from acetic acid, nitric acid or citric acid, preferably acetic acid. During the subsequent roasting process to prepare the carrier, the binder will be completely decomposed, and it can be considered that the catalyst finally obtained does not contain the binder component.

[0060] In the present invention, the amount of the binder is 1-3 wt%, preferably 1.5-2.5 wt%, based on the total weight of the catalyst.

[0061] According to the present invention, in step (2), the molding can adopt a rolling molding method, and conventional processes and equipment can be used. The molding process includes adding the solid material to a ball rolling machine, and spraying the binder-containing solution onto the material in the ball rolling machine, mixing and continuously rolling to obtain a spherical molded product.

[0062] According to the present invention, in step (2), the aging is preferably carried out under a steam atmosphere, and the aging conditions include: a temperature of 60-100° C., preferably 80-90° C.; and a time of 10-30 h, preferably 16-24 h.

[0063] According to the present invention, in step (2), the drying conditions include: temperature of 100-150° C., preferably 120-130° C.; time of 4-10 h, preferably 5-8 h.

[0064] According to the present invention, in step (2), the calcination conditions include: temperature of 380-550° C., preferably 400-450° C.; time of 3-10 h, preferably 4-6 h.

[0065] According to the present invention, in step (2), the calcination is carried out under an inert protective gas atmosphere. The inert protective gas can be an inert gas such as nitrogen, helium, argon, etc., preferably nitrogen. In the present invention, by using aluminum hydroxide with a specific pore structure to quickly de-powder and calcine at a relatively low temperature, the obtained calcined product mainly contains AlO(OH), χ-Al2O3 and η-Al2O3 phases, and the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 is 1:(2-5):(0.2-0.6), preferably 1:(3-4):(0.4-0.5), and basically does not contain γ-Al2O3, and the macropore content is high. After the active component is loaded, the catalyst obtained has a pore structure measured by mercury intrusion, in which the sum of the pore volume with a pore diameter greater than 75nm accounts for not less than 35% by volume, thereby having high decarbonylation sulfide activity and stability, and the service life of the catalyst is greatly improved.

[0066] According to the present invention, in step (3), the loading of alkali metal salts and nickel salts can be achieved by impregnating the support in an impregnation solution containing the above salts. The present invention has no particular limitation on the impregnation process, and conventional impregnation methods in the art can be used, and one-step impregnation or multi-step impregnation can be used. When one-step impregnation is used, the impregnation solution is a solution containing alkali metal salts and nickel salts; when multi-step impregnation is used, the impregnation solution can be a solution containing alkali metal salts and a solution containing nickel salts, respectively. The support can be impregnated in the solution containing alkali metal salts and the solution containing nickel salts successively. The present invention has no particular limitation on the order of impregnation of the support in different impregnation solutions. The impregnation solution can be obtained by dissolving the alkali metal salt and / or nickel salt in a solvent. Among them, the alkali metal salt can preferably be a carbonate and / or nitrate of an alkali metal, the nickel salt can preferably be at least one of nickel nitrate, nickel carbonate and nickel acetate, the alkali metal can preferably be sodium and / or potassium, and the solvent can preferably be water.

[0067] According to the present invention, in the impregnation solution, the amount of the alkali metal salt is such that the content of the alkali metal oxide loaded on the carrier is 2-6wt%, preferably 3-4wt%, based on the total weight of the catalyst; the amount of the nickel salt is such that the content of the nickel oxide loaded on the carrier is 1-4wt%, preferably 2-3wt%, based on the total weight of the catalyst; the amounts of the alkali metal salt and the nickel salt are such that in the catalyst, the content of the alkali metal oxide is higher than that of the nickel oxide, preferably, the content of the alkali metal oxide is 0.5-3wt% higher than that of the nickel oxide.

[0068] According to the present invention, in step (3), the impregnation can be carried out at room temperature, and the impregnation time is preferably 1-4 hours, more preferably 2-3 hours.

[0069] According to the present invention, in step (3), the impregnated support is dried under the following conditions: a temperature of 100-160° C., preferably 120-140° C., and a drying time of 2-8 hours, preferably 4-6 hours.

[0070] According to the present invention, in step (3), the dried support is calcined to obtain the COS conversion catalyst. Preferably, the calcination conditions include: a temperature of 360-600°C, preferably 400-500°C; and a time of 3-8 hours, preferably 3-5 hours.

[0071] The catalyst prepared by the above method, wherein at least part of the carrier is AlO(OH), χ-Al2O3 and η-Al2O3 phases, based on the total weight of the catalyst, the content of γ-Al2O3 does not exceed 0.5wt%, and the total content of AlO(OH), χ-Al2O3 and η-Al2O3 is not less than 90wt%, wherein the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 is 1:(2-5):(0.2-0.6); the carrier is loaded with alkali metal oxide and nickel oxide; based on the total weight of the catalyst, the content of the carrier is 90-97wt%, the content of the alkali metal oxide is 2-6wt%, and the content of the nickel oxide is 1-4wt%; in the catalyst, the content of the alkali metal oxide is preferably higher than that of the nickel oxide; the specific surface area of the catalyst is greater than 300m 2 / g, with a pore volume greater than 0.45mL / g; the catalyst has a weakly basic center content of 2.15-2.3mmolCO2 / g catalyst; the pore structure of the catalyst measured by mercury intrusion porosimetry shows a bimodal pore size distribution, with peaks located at 1000-4000nm and 4-20nm, respectively; based on the total pore volume of the catalyst, the sum of pores with a pore size greater than 75nm accounts for more than 35% by volume. The prepared catalyst has the advantages of high catalytic activity, good activity stability, long service life, and low reaction temperature, and can achieve a COS conversion rate of ≥99% with a service life of more than 8 years.

[0072] The second aspect of the present invention provides use of the catalyst described in the first aspect in removing carbonyl sulfide.

[0073] In the present invention, the catalyst has a specific content of alkali metal oxide and nickel oxide and a carrier composed of a specific phase, and has a high specific surface area and a large pore volume. It can efficiently convert carbonyl sulfide, has high catalytic activity, good activity stability, low operating temperature, long service life, and a wide range of applications. It can be used for the efficient removal of carbonyl sulfide in industries including but not limited to natural gas chemical industry and coal chemical industry.

[0074] The third aspect of the present invention provides a method for removing carbonyl sulfide from natural gas, comprising: contacting raw natural gas with a desulfurizing agent to react and separate to obtain product natural gas and H2S; wherein,

[0075] The desulfurizing agent is the catalyst described in the first aspect above;

[0076] The reaction conditions include: the volume space velocity of the raw natural gas is 1000-5000h -1 , the reaction temperature is 100-140℃.

[0077] In the present invention, the raw natural gas refers to natural gas that needs to be desulfurized, and the product natural gas refers to natural gas whose sulfur content meets the use requirements after desulfurization. The raw natural gas mainly contains methane and a small amount of alkanes such as ethane, as well as carbon dioxide, carbon monoxide, nitrogen, hydrogen, hydrogen sulfide, water vapor, organic sulfur, etc., among which the organic sulfur mainly includes carbonyl sulfide (COS) in the raw natural gas with a content of 20-600 mg / m 3 The method of the present invention can effectively convert carbonyl sulfide, the conversion reaction has good stability, the catalyst has a long service life, the reaction temperature is low, and the conversion rate of carbonyl sulfide can reach more than 99%, thereby significantly reducing the total sulfur content in the desulfurized natural gas product. Preferably, the total sulfur content in the desulfurized natural gas product is ≤20mg / m 3 .

[0078] The present invention will be described in detail below through examples. In the following examples and comparative examples, unless otherwise specified, all materials used are common commercially available products.

[0079] Aluminum hydroxide quick-drying powder was purchased from Shandong Zibo Kaiou New Materials Co., Ltd.

[0080] Example 1

[0081] (1) 1343g aluminum hydroxide was quickly de-powdered (specific surface area of 350m 2 / g, pore volume 0.60mL / g), 30g sesbania powder were mixed evenly to form a solid material;

[0082] (2) adding 15 g of acetic acid to 80 g of water and stirring uniformly to prepare an acetic acid solution; placing the solid material obtained in step (1) in a ball rolling machine, spraying the above-mentioned acetic acid solution on the solid material in the ball rolling machine, mixing and rolling the solid material to obtain small balls with a diameter of Φ3-4 mm; then, aging the small balls in a steam atmosphere at 90°C for 20 h, drying at 130°C for 5 h, and calcining at 400°C for 6 h in a nitrogen atmosphere to obtain a carrier;

[0083] (3) 58.7 g of potassium carbonate and 49.0 g of nickel nitrate were loaded onto the support prepared in step (2) by an equal volume impregnation method for 2.5 h; the impregnated support was dried at 130° C. for 4 h and then calcined at 400° C. for 5 h to obtain a catalyst (denoted as S1).

[0084] S1 was subjected to XRD test (Japan Rigaku Smartlab-3 X-ray diffractometer, using a one-dimensional detector, test parameters: tube voltage 40 kV, tube current 40 μA, Cu target, optical slit system IS = 0.5°, RS1 = 20 mm, RS2 = 20 mm, scanning speed 10 (d·min -1 ), scanning range 10°-70°), the results are as follows Figure 1As shown in Figure 2, the characteristic diffraction peaks of AlO(OH) appear at 14.44°, 28.24°, 38.24° and 48.80°, the characteristic diffraction peaks of η-Al2O3 appear at 37.31°, 45.93° and 66.76°, the characteristic diffraction peaks of χ-Al2O3 appear at 37.31°, 42.41°, 45.56° and 67.50°, and the characteristic diffraction peaks of χ-Al2O3 appear at 37.80°, 45.9 No characteristic diffraction peaks of γ-Al2O3 were observed at 0° and 67.00°; further, based on the peak areas of the above characteristic diffraction peaks of the test sample, the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 was calculated to be 1:3.5:0.45. Based on the total weight of S1, the content of γ-Al2O3 was 0.01wt%, and the total content of AlO(OH), χ-Al2O3 and η-Al2O3 was 94Wt%.

[0085] The pore structure of S1 was tested by mercury intrusion (PoreMaster-60 fully automatic mercury intrusion instrument from Quantachrome, USA, with a pore size range of 0.003-1000 μm, a low-pressure analysis pressure range of 1.5-350 kPa, and a high-pressure analysis pressure range of 140-420 kPa). The results showed that the sum of the pore volume with a pore size greater than 75 nm accounts for 48% of the total pore volume; the pore size distribution is as follows: Figure 2 As shown, it can be seen that the pore size has a bimodal distribution, with the peak positions being located at 1000-4000 nm and 4-20 nm respectively.

[0086] The specific surface area of S1 was measured by nitrogen adsorption method and was 314 m 2 ·g -1 The pore volume of S1 was measured by mercury intrusion porosimetry and was 0.53 mL·g -1 .

[0087] The weak basic center content of the catalyst was determined by the carbon dioxide temperature-programmed desorption method. The test process was as follows: 250 mg of catalyst sample was weighed, and the temperature was raised to 300°C under high-purity nitrogen (flow rate 30 mL / min) for catalyst pretreatment, maintained at 300°C for 20 minutes, then dropped to 30°C, switched to CO2 (flow rate 30 mL / min, concentration 99.999%) for adsorption for 30 minutes, and nitrogen was purged for 15 minutes after the adsorption was completed. The temperature was then raised to 700°C for desorption, and the heating rate was maintained at 10°C / min. During the heating process, a mass spectrometer was used to record the changing trend of CO2 (m / z=44) to obtain a CO2-TPD spectrum. The weak basic center content of S1 was calculated to be 2.25 mmol CO2 / g catalyst based on the amount of CO2 at a desorption temperature below 200°C.

[0088] The content of each component in catalyst S1, the phase composition and the physicochemical indicators are shown in Table 1.

[0089] Example 2

[0090] (1) 1357g aluminum hydroxide was quickly de-powdered (specific surface area 360m 2 / g, pore volume 0.65mL / g), 40g sesbania powder were mixed evenly to form a solid material;

[0091] (2) adding 20 g of acetic acid to 90 g of water and stirring uniformly to prepare an acetic acid solution; placing the solid material obtained in step (1) in a ball rolling machine, spraying the above-mentioned acetic acid solution onto the solid material in the ball rolling machine, mixing and rolling the solid material to obtain small balls with a diameter of Φ3-4 mm; then aging the small balls in a water vapor atmosphere at 85°C for 16 hours, drying at 125°C for 8 hours, and calcining at 430°C for 5 hours in a nitrogen atmosphere to obtain a carrier;

[0092] (3) 51.3 g of sodium carbonate and 31.9 g of nickel carbonate were loaded onto the support prepared in step (2) by an equal volume impregnation method for 3 h; the impregnated support was dried at 120° C. for 5 h and calcined at 500° C. for 3 h to obtain a catalyst (denoted as S2).

[0093] The content of each component in catalyst S2, the phase composition and the physicochemical indicators are shown in Table 1.

[0094] Example 3

[0095] (1) 1329g aluminum hydroxide was quickly de-powdered (specific surface area of 320m 2 / g, pore volume 0.53mL / g), 20g sesbania powder were mixed evenly to form a solid material;

[0096] (2) adding 25 g of acetic acid to 90 g of water and stirring to form an acetic acid solution; placing the solid material obtained in step (1) in a ball rolling machine, spraying the above-mentioned nitric acid solution onto the material in the ball rolling machine, mixing and rolling the material to obtain small balls with a diameter of Φ3-4 mm; then aging the small balls in a steam atmosphere at 80°C for 24 hours, drying at 120°C for 6 hours, and calcining at 450°C for 4 hours in a nitrogen atmosphere to obtain a carrier;

[0097] (3) 86.0 g of potassium nitrate and 100 g of nickel acetate tetrahydrate were loaded onto the support prepared in step (2) by an equal volume impregnation method for 2 h; the impregnated support was dried at 140° C. for 6 h and calcined at 450° C. for 4 h to obtain a catalyst (denoted as S3).

[0098] The content of each component, phase composition and physical and chemical indicators of catalyst S3 are shown in Table 1.

[0099] Example 4

[0100] (1) 1300g aluminum hydroxide was quickly de-powdered (specific surface area of 326m 2 / g, pore volume is 0.45mL / g), 20g methyl cellulose are mixed evenly to form a solid material;

[0101] (2) adding 30 g of citric acid to 80 g of water and stirring uniformly to prepare a citric acid solution; placing the solid material obtained in step (1) in a ball rolling machine, spraying the above-mentioned citric acid solution onto the material in the ball rolling machine, mixing and rolling the material to obtain small balls with a diameter of Φ3-4 mm; then aging the small balls in a water vapor atmosphere at 70°C for 12 hours, drying at 115°C for 4 hours, and calcining at 380°C for 3 hours in a nitrogen atmosphere to obtain a carrier;

[0102] (3) 73.4 g of potassium carbonate and 63.7 g of nickel carbonate were loaded onto the support prepared in step (2) by an equal volume impregnation method for 4 h; the impregnated support was dried at 100° C. for 2 h and calcined at 380° C. for 6 h to obtain a catalyst (denoted as S4).

[0103] The content of each component, phase composition and physical and chemical indicators of catalyst S4 are shown in Table 1.

[0104] Example 5

[0105] (1) 1386g aluminum hydroxide was quickly de-powdered (specific surface area of 330m 2 / g, pore volume is 0.57ml / g), 50g starch is mixed evenly to form a solid material;

[0106] (2) 54.8 g of acetic acid was added to 100 ml of water and stirred to form an acetic acid solution; the solid material obtained in step (1) was placed in a ball rolling machine, and the nitric acid solution was sprayed onto the material in the ball rolling machine, mixed, and rolled to form small balls with a diameter of Φ3-4 mm; the small balls were aged at 95° C. in a steam atmosphere for 28 h, dried at 140° C. for 10 h, and calcined at 520° C. in a nitrogen atmosphere for 8 h to obtain a carrier;

[0107] (3) 54.8 g of sodium carbonate and 15.9 g of nickel carbonate were loaded onto the support prepared in step (2) by an equal volume impregnation method for 1 h; the impregnated support was dried at 150° C. for 5 h and calcined at 550° C. for 8 h to obtain a catalyst (denoted as S5).

[0108] The content of each component, phase composition and physical and chemical indicators of catalyst S5 are shown in Table 1.

[0109] Example 6

[0110] The method of Example 1 was followed, except that the calcination temperature of the prepared carrier in step (2) was 600° C., and the calcination temperature of the impregnated carrier in step (3) was 580° C. Other conditions were the same as those in Example 1. A catalyst (denoted as S6) was obtained.

[0111] The content of each component in catalyst S6, the phase composition and the physical and chemical indicators are shown in Table 1.

[0112] Example 7

[0113] The method of Example 1 was followed, except that the amount of potassium carbonate used in step (3) was 29.4 g and the amount of nickel nitrate used was 98 g. Other conditions were the same as those of Example 1. A catalyst (denoted as S7) was obtained.

[0114] The content of each component, phase composition and physical and chemical indicators of catalyst S7 are shown in Table 1.

[0115] Comparative Example 1

[0116] The method of Example 1 was followed, except that nickel nitrate was not added in step (3). Other conditions were the same as those of Example 1. A catalyst (denoted as D1) was obtained.

[0117] The content of each component, phase composition and physicochemical indicators of catalyst D1 are shown in Table 1.

[0118] Comparative Example 2

[0119] The method of Example 2 was followed, except that sodium carbonate was not added in step (3). Other conditions were the same as those of Example 2. A catalyst (denoted as D2) was obtained.

[0120] The content of each component, phase composition and physicochemical indicators of catalyst D2 are shown in Table 1.

[0121] Comparative Example 3

[0122] The method of Example 1 was followed, except that metatitanic acid was used in place of aluminum hydroxide for rapid de-powdering in step (1). Other conditions were the same as those of Example 1. A catalyst (denoted as D3) was obtained.

[0123] The content of each component, phase composition and physicochemical indicators of catalyst D3 are shown in Table 1.

[0124] Comparative Example 4

[0125] The method of Example 1 was followed, except that step (1) was omitted and 1200 g of α-Al₂O₃ powder was used instead of the solid material obtained in step (1). Steps (2) and (3) were then carried out in sequence. Other conditions were the same as those of Example 1. A catalyst (denoted as D4) was obtained.

[0126] The content of each component, phase composition and physicochemical indicators of catalyst D4 are shown in Table 1.

[0127] Comparative Example 5

[0128] The method of Example 1 was followed, except that in step (1), the amount of alumina powder was adjusted from 1343 g to 1143 g; and in step (3), the "58.7 g potassium carbonate and 49.0 g nickel nitrate" were replaced with "278.9 g potassium carbonate and 24.5 g nickel nitrate." Other conditions were the same as in Example 1. A catalyst (denoted as D5) was obtained.

[0129] The content of each component, phase composition and physicochemical indicators of catalyst D5 are shown in Table 1.

[0130] Comparative Example 6

[0131] The method of Example 1 was followed, except that the calcination temperature in step (2) was changed to 800° C., and the calcination temperature of the impregnated support in step (3) was also 800° C. The other conditions were the same as those in Example 1. A catalyst (denoted as D6) was obtained.

[0132] The pore size distribution test (mercury intrusion method) of catalyst D6 is as follows: Figure 3 The content of each component, phase composition and physicochemical indicators of catalyst D6 are shown in Table 1.

[0133] Table 1

[0134]

[0135] Table 1

[0136]

[0137]

[0138] Note: In Table 1, the macropore ratio is the percentage of the sum of the pore volume with a pore diameter greater than 75 nm to the total pore volume of the catalyst;

[0139] The weight percentage of the phase is based on the total weight of the catalyst

[0140] Test Case

[0141] The catalysts S1-S7 and D1-D6 prepared in Examples 1-7 and Comparative Examples 1-6 were subjected to COS conversion tests in a 10 mL microreactor activity evaluation device to evaluate the catalyst performance. The method is as follows:

[0142] Aging treatment: Catalysts S1-S7 and D1-D6 were subjected to severe aging (calcined at 550°C for 2h, then heated with water vapor at a volume space velocity of 1000h -1 The catalyst was aged using steam for 8, 12, and 16 hours, respectively. The resulting harshly aged catalysts simulated the performance of catalysts after 4, 6, and 8 years of use, respectively.

[0143] COS conversion test: The reactor of the micro-reactor activity evaluation device is made of a stainless steel tube with an inner diameter of 20 mm. The reactor is placed in a constant temperature box. The specific process flow is as follows: Figure 4 The loading amount of the catalyst after harsh aging was 10 mL / (20-40 mesh), and quartz sand of the same particle size was loaded on the top for mixing and preheating. A Shimadzu GC-2014 gas chromatograph was used to online analyze the contents of H2S and COS in the reactor inlet and outlet gases. The TCD detector was used to analyze major sulfides, with GDX-301 as the support, the column temperature was 120°C, hydrogen as the carrier gas, and the post-column flow rate was 25 mL / min; the FPD detector was used to analyze trace sulfides, with GDX-301 as the support, the column temperature was 80°C, nitrogen as the carrier gas, and the post-column flow rate was 30 mL / min.

[0144] The composition of the raw natural gas at the reactor inlet is: CH4 content 91.49v%, ethane content 0.5v%, H2 content 0.01v%, CO2 content 3v%, water vapor content 5v%, H2S content 50mg / m 3 , methyl mercaptan content 11mg / m 3 、COS content 500mg / m 3 ;The volume space velocity of raw natural gas is 5000h -1 The reaction temperature was 130°C and the reaction time was 24 hours. The products at the reactor outlet were separated to obtain product natural gas and H2S. From the start of the reaction, the COS conversion rate and the total sulfur content in the product natural gas were tested every 1 hour until the end of the test. The average of the test results was taken as the final result. The results are shown in Table 2. The COS conversion rate was calculated according to formula (I):

[0145]

[0146] In formula (I), M0 and M1 represent the volume concentrations of COS at the inlet and outlet, respectively.

[0147] Table 2

[0148]

[0149] As can be seen from Table 2, the COS conversion rates of the catalysts S1-S7 provided by the present invention can all reach over 99% in the fourth year of use, and can still reach over 98.5% in the eighth year of use, showing excellent COS conversion activity, good activity stability, minimal activity decay after long-term use, and a service life of over 8 years. Furthermore, the catalysts are suitable for relatively low reaction temperatures (e.g., the reaction temperature of 130° C. used in the above-mentioned test), and can well meet the requirements of industrial plants for COS removal, resulting in a total sulfur content of less than 20 mg / m3 in the desulfurized natural gas product. 3 , meeting the Class I gas requirements specified in GB17820-2018. However, the carbonyl sulfide conversion activity of D1-D6 is significantly lower, and the catalyst life is significantly shorter.

[0150] The present invention designs the composition of the catalyst and utilizes the synergistic effect of specific contents of alkali metal oxides and nickel oxide and a carrier composed of a specific phase. This gives the catalyst the advantages of high catalytic activity, good activity stability, long service life, and low reaction temperature in the COS conversion reaction. The COS conversion rate can be achieved at least 99%, and the service life can reach more than 8 years.

[0151] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A catalyst for removing carbonyl sulfide from natural gas, characterized in that: The catalyst comprises: a carrier, an alkali metal oxide and nickel oxide supported on the carrier, wherein the alkali metal oxide is sodium oxide and / or potassium oxide; wherein, based on the total weight of the catalyst, the content of the carrier is 90-97wt%, the content of the alkali metal oxide is 2-6wt%, and the content of the nickel oxide is 1-4wt%; and the content of the alkali metal oxide is 0.5-3wt% higher than that of the nickel oxide. At least a portion of the support is composed of AlO(OH), χ-Al2O3, and η-Al2O3 phases. In the catalyst, based on the total weight of the catalyst, the content of γ-Al2O3 does not exceed 0.5wt%, and the total content of AlO(OH), χ-Al2O3, and η-Al2O3 is not less than 90wt%; and in the support, the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 is 1:(2-5):(0.2-0.6); The weak alkaline center content of the catalyst is 2.15-2.3 mmolCO2 / g catalyst; the pore structure of the catalyst measured by mercury intrusion porosimetry has a bimodal pore size distribution, with the bimodal peaks located at 1000-4000 nm and 4-20 nm, respectively; based on the total pore volume of the catalyst, the sum of the pore volume with a pore diameter greater than 75 nm accounts for more than 35% by volume.

2. The catalyst according to claim 1, wherein Based on the total weight of the catalyst, the content of the carrier is 93-95 wt %, the content of the alkali metal oxide is 3-4 wt %, and the content of nickel oxide is 2-3 wt %.

3. The catalyst according to claim 1, wherein In the carrier, the weight ratio of AlO(OH):χ-Al2O3:η-Al2O3 is 1:(3-4):(0.4-0.5).

4. The catalyst according to any one of claims 1 to 3, wherein The specific surface area of the catalyst is greater than 300m 2 / g, and the pore volume is greater than 0.45mL / g.

5. The catalyst according to claim 1, wherein Based on the total pore volume of the catalyst, the total volume of pores with a pore diameter greater than 75 nm accounts for 35-55% by volume.

6. A method for removing carbonyl sulfide from natural gas, comprising: The raw natural gas is contacted with the desulfurizer to react and separate to obtain product natural gas and H2S; wherein, The desulfurizer is the catalyst according to any one of claims 1 to 5; The reaction conditions include: the volume space velocity of the raw natural gas is 1000-5000h -1 , the reaction temperature is 100-140℃.

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