Desulfurization method of propylene-rich stream

Abstract

The present invention discloses a propylene-rich material flow desulfurization method, which comprises: in a liquid phase fixed bed reactor, contacting a propylene-rich material flow with a desulfurization catalyst, and carrying out desulfurization treatment, wherein the desulfurization catalyst contains Al2O3, Na, Mg, Ag and rare earth metal; and (2) carrying out regeneration treatment on the used desulfurization catalyst by using propane containing 5-10vol% of hydrogen as regeneration gas. According to the method disclosed by the invention, Na-Mg-Ag-rare earth metal-Al2O3 is adopted as a desulfurization catalyst, so that the desulfurization capacity is good, sulfur-containing compounds in the propylene-rich material flow prepared by directly cracking crude oil can be effectively removed, the use temperature is low, additional reaction is not introduced, and downstream hydrogenation and separation processes are not influenced; and the desulfurization catalyst is repeatedly regenerated under the condition that hydrogen and propane are used as media.

Description

Technical Field

[0001] This invention relates to the field of desulfurization technology, and more specifically, to a desulfurization method for propylene-rich streams. Background Technology

[0002] In the crude oil refining process, many impurities in crude oil are removed and refined at the later stages of the refining process, targeting products from different distillation ranges. Because crude oil steam cracking technology makes it difficult to remove and refine impurities at the earlier stages of steam cracking, impurity removal can only be carried out specifically in the separation process. Unlike ordinary cracking processes, crude oil cracked gas generally contains hydrogen sulfide and organic sulfides. While most of the hydrogen sulfide can be removed in an alkaline scrubbing tower, carbonyl sulfide, carbon disulfide, and organic sulfur cannot be removed in existing separation processes. This is highly detrimental to downstream separation and the production of ethylene and propylene, necessitating the establishment of dedicated organic sulfur refining and removal units. Sulfur compounds can be divided into inorganic sulfur and organic sulfur. Inorganic sulfur mainly includes hydrogen sulfide and sulfur dioxide, which are relatively easy to remove industrially using solvent absorption or desulfurizing agents. Organic sulfur mainly includes thiols, thioethers, thiophene, carbonyl sulfide, carbon disulfide, etc., which are more difficult to remove. Currently, the commonly used industrial methods are hydrogenation and catalytic hydrolysis for desulfurization.

[0003] Hydrodesulfurization involves catalytically hydrogenating organic sulfur in the feedstock to convert it into inorganic sulfur, which is then removed. Currently, the hydrodesulfurizing agents used in industry are mainly catalysts with Co, Mo, and Ni as the main active components. CN114768863A discloses a heavy oil hydrodesulfurization catalyst that adds a special molecular sieve coating to an alumina support loaded with active metal W-Mo-Ni-Co to block contact between the active metal and sulfur, reducing sulfur poisoning of the active metal. However, the preparation process of this catalyst is complex, the reaction temperature is high, and the investment and operating costs are increased.

[0004] Catalytic hydrolysis desulfurization involves first hydrolyzing sulfides onto a catalyst to convert them into hydrogen sulfide, which is then adsorbed and removed. Currently, commercially available traditional organic sulfur hydrolysis desulfurizers mainly include alumina-based, titanium dioxide-based, or activated carbon-based iron oxide desulfurizers, zinc oxide desulfurizers, activated carbon desulfurizers, and nano-adsorbent materials. Organic sulfur (mainly COS) and inorganic sulfur (mainly H2S) present in blast furnace gas are primarily removed using hydrolysis desulfurizers. Traditional organic sulfur hydrolysis desulfurizers have short service lives, high replacement costs, and the waste generated after replacement places a heavy burden on steel companies.

[0005] The propylene-rich stream obtained from the staged separation of cracked gas contains 1-7 mol% MAPD and a small amount of butadiene, which are highly reactive substances that easily initiate hydrogenation, oxidation, polymerization, and adsorption reactions on the surface of the desulfurization catalyst. How to effectively remove carbonyl sulfide, carbon disulfide, and organic sulfur without triggering excessive catalytic reactions places extremely high demands on the desulfurization process and catalyst performance. Furthermore, the total sulfur content in the propylene-rich stream obtained from direct crude oil cracking is generally tens to hundreds of ppm. Using adsorption desulfurization, the catalyst cannot operate for extended periods; repeated regeneration is necessary to ensure long-term catalyst utilization. Currently, nitrogen and methane hydrogen are commonly used regeneration gases in industrial ethylene cracking units. However, due to the frequent regeneration of desiccants and hydrogenation catalysts, the usage of nitrogen and methane hydrogen cannot guarantee the regeneration and reuse of the desulfurization catalyst. Therefore, it is essential to find a new regeneration gas medium for the desulfurization catalyst. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of difficulty in removing organic sulfur and difficulty in regenerating desulfurization catalysts in existing technologies, and to provide a desulfurization method for propylene-rich streams. This desulfurization method uses Na-Mg-Ag-rare earth metal-Al2O3 as a desulfurization catalyst to remove trace sulfur-containing compounds in propylene-rich streams in the direct cracking of crude oil to propylene process. It can achieve efficient sulfur removal and purification under normal low temperature liquid phase conditions, without triggering other reactions in the propylene-rich streams, and the desulfurization catalyst can be repeatedly regenerated and used.

[0007] To achieve the above objectives, the present invention provides a desulfurization method for propylene-rich streams, the desulfurization method comprising:

[0008] (1) In a liquid-phase fixed-bed reactor, a propylene-rich stream is contacted with a desulfurization catalyst for desulfurization treatment; wherein the desulfurization catalyst contains Al2O3, Na, Mg, Ag and rare earth metals;

[0009] (2) Use propane containing 5-10 vol% hydrogen as regeneration gas to regenerate the desulfurization catalyst after use.

[0010] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0011] (1) The method of the present invention uses Na-Mg-Ag-rare earth metal-Al2O3 as a desulfurization catalyst, which has good desulfurization ability and can effectively remove sulfur-containing compounds from the propylene-rich stream produced by direct cracking of crude oil. It has a low operating temperature, does not introduce additional reactions, and does not affect the downstream hydrogenation and separation process. Furthermore, the desulfurization catalyst is repeatedly regenerated under the conditions of hydrogen and propane as media, and the desulfurization performance decays very little.

[0012] (2) The method of the present invention uses propane containing 5-10 vol% hydrogen as a medium to regenerate the desulfurization catalyst and remove the sulfur-containing compounds adsorbed on the catalyst. The removed sulfur-containing compounds enter the light hydrocarbon cracking furnace with the regeneration gas to react and generate hydrogen sulfide and sulfur dioxide, which are then absorbed by the alkaline washing tower. It is green and environmentally friendly, with no environmental pollution problems, and ensures the long-term stable operation capability of the crude oil cracking unit. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the desulfurization reaction process of a propylene-rich stream obtained from direct cracking of crude oil according to one embodiment of the present invention.

[0014] Figure 2 This is a schematic diagram of the regeneration process of a desulfurization catalyst provided in one embodiment of the present invention.

[0015] Explanation of reference numerals in the attached figures

[0016] Figure 1 middle:

[0017] Ⅰ: Ethane removal tower; Ⅱ: Heat exchanger before desulfurization reactor;

[0018] III: Desulfurization reactor (single-stage bed, one in operation and one on standby); IV: Heat exchanger before the C2 hydrogenation reactor;

[0019] V: C2 hydrogenation reactor (first stage / several reactors in series);

[0020] 1: Material exiting from the top of the ethane stripper; 2: Material entering the desulfurization reactor;

[0021] 3: Outlet material of the desulfurization reactor; 4: Inlet material of the C2 hydrogenation reactor;

[0022] 5: Hydrogen; 6: Outlet material from the C2 hydrogenation reactor.

[0023] Figure 2 middle:

[0024] A: Ethylene distillation column; B: Heater; C: Desulfurization reactor;

[0025] D: Heat exchanger; E: Light hydrocarbon cracking furnace; F: Alkali washing tower;

[0026] 11: Partial recycled ethane feedstock; 11': Remaining recycled ethane feedstock; 12: Purge nitrogen;

[0027] 13: Regenerated gas after heating (circulating ethane); 14: Regenerated sulfur-containing circulating ethane;

[0028] 15: Sulfur-containing ethane cracking feedstock; 16: Cracking gas; 17: Cracking gas after alkali washing. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] This invention provides a desulfurization method for propylene-rich streams, the desulfurization method comprising:

[0031] (1) In a liquid-phase fixed-bed reactor, a propylene-rich stream is contacted with a desulfurization catalyst for desulfurization treatment; wherein the desulfurization catalyst contains Al2O3, Na, Mg, Ag and rare earth metals;

[0032] (2) Use propane containing 5-10 vol% hydrogen as regeneration gas to regenerate the desulfurization catalyst after use.

[0033] According to the present invention, the propane containing 5-10 vol% hydrogen is obtained by adding a measured amount of hydrogen or methane hydrogen to the propane stream. Preferably, the methane hydrogen contains more than 80% hydrogen by mass and less than 5 ppm CO by mass.

[0034] According to the present invention, the methane hydrogen can be derived from the outlet of the methanation reactor.

[0035] This invention employs a propane stream containing 5-10 vol% hydrogen to regenerate a desulfurization catalyst. The regeneration medium is a recycled propane stream containing 5-10 vol% hydrogen, used at a relatively high temperature to remove sulfur-containing compounds adsorbed on the desulfurization catalyst. This method allows for the removal of trace amounts of sulfur from the desulfurization catalyst and its repeated reuse through reduction and regeneration.

[0036] According to this invention, the inventors unexpectedly discovered through research that the Na-Mg-Ag-rare earth metal-Al2O3 catalyst not only possesses excellent desulfurization capability, achieving desulfurization at a lower temperature—far below the desulfurization temperatures of hydrogenation and hydrolysis—thus avoiding unnecessary reactions; but also, under propane and hydrogen as media, this desulfurization catalyst can be repeatedly regenerated with minimal degradation in desulfurization performance. The method of this invention has advantages such as simple process, no additional reactions, no impact on downstream hydrogenation and separation processes, and energy savings.

[0037] According to some embodiments of the present invention, based on the total weight of the desulfurization catalyst, the weight content of Na is 2-15 wt%, preferably 5-10 wt%; the weight content of Mg is 2-8 wt%, preferably 4-6 wt%; the weight content of Ag is 0.5-5 wt%, preferably 1-3 wt%; and the weight content of rare earth metals is 15-30 wt%, preferably 18-25 wt%.

[0038] According to this invention, the content of each element can be determined by ICP spectroscopy or calculated based on the input amount.

[0039] According to some embodiments of the present invention, the rare earth metal is selected from at least one of La, Ce, Pr, Nd, Sm, Yb, Lu, Sc and Y.

[0040] Preferably, the rare earth metal is selected from at least one of La, Ce, Pr, Lu, Sc and Y.

[0041] According to some embodiments of the present invention, the desulfurization catalyst further contains a modifying component; the modifying component is selected from at least one of K, Ca, Ga, In, Zn, Mn, Re, Au, Group VIII elements, Group IB elements, Group IVA elements, Group IVB elements, Group VA elements, and Group VIB elements.

[0042] According to some preferred embodiments of the present invention, the modified component is selected from at least one of the elements K, Ca, Ga, In, Fe, Mn, Re, Co, Pb, Zr, Mo and W.

[0043] According to some embodiments of the present invention, the weight content of the modified component is <10wt%, preferably 0.5-5wt%, based on the total weight of the desulfurization catalyst.

[0044] According to some embodiments of the present invention, the desulfurization catalyst further contains Al(OH)3.

[0045] According to some embodiments of the present invention, based on the total weight of Al2O3 and Al(OH)3, the weight content of the γ phase in the crystal form of Al2O3 is >80%, and the weight content of Al(OH)3 is <10wt%.

[0046] According to some embodiments of the present invention, the desulfurization catalyst of the present invention is formed by mixing and pressing Al2O3, Na, Mg, Ag, rare earth metals and modifying components; the weight percentage of Na in the catalyst is 2-15%, the weight percentage of Mg is 2-8%, the weight percentage of Ag is 0.5-5%, the weight percentage of rare earth metals is 15-30%, the weight percentage of modifying components is <10%, and the remainder is a mixture of Al2O3 and Al(OH)3, wherein the weight percentage of the γ phase in the crystal form of Al2O3 is >80%, and the weight percentage of Al(OH)3 is <10%.

[0047] According to some embodiments of the present invention, the specific surface area of ​​the desulfurization catalyst is 100-500 m². 2 / g, preferably 180-400m 2 / g, more preferably 200-300m 2 / g.

[0048] According to the present invention, the aforementioned desulfurization catalyst is prepared by mixing, pressing, and impregnating with a loading agent.

[0049] According to some embodiments of the present invention, a method for preparing a desulfurization catalyst is provided, which includes the following steps:

[0050] Step 1: Mix the powdered raw materials; add an aqueous solution containing Na and Mg compounds to the powdered raw materials, then knead and shape them; perform the first drying, tableting and first calcination to obtain the catalyst precursor;

[0051] Step 2: Load the precursor of the modified component onto the catalyst precursor obtained in Step 1, and perform a second drying and a second calcination.

[0052] The preparation of this invention also includes a reduction step, preferably performed before the use of a catalyst, and the specific reduction conditions include:

[0053] The reduction temperature is 160-320℃, preferably 200-280℃; the temperature fluctuation range is ±2℃, preferably ±1℃; the time is greater than 6 hours, preferably 10-24 hours.

[0054] According to some embodiments of the present invention, the gas used for reduction includes hydrogen and other gases, the other gases being nitrogen and / or methane, and the volume content of hydrogen being 50-100%.

[0055] According to some embodiments of the present invention, the powdered raw material includes alumina powder, rare earth metal compound powder, and silver compound powder. The silver compound is selected from at least one of silver nitrate, silver oxide, and silver perrhenate.

[0056] According to some embodiments of the present invention, the alumina powder is selected from boehmite powder and optionally alumina powder.

[0057] According to some embodiments of the present invention, the alumina powder is obtained by calcining pseudoboehmite powder at a temperature selected from 350-650°C.

[0058] According to some embodiments of the present invention, the amount of alumina powder used accounts for 0-20 wt% of the total amount of alumina powder.

[0059] According to some embodiments of the present invention, the powdered raw material further includes a forming and pore-forming agent, wherein the amount of the forming and pore-forming agent accounts for 0-5 wt% of the total amount of the alumina powder.

[0060] According to some embodiments of the present invention, the molding pore-forming agent is selected from at least one of cellulose, urea, ethylenediamine and polymer.

[0061] According to some embodiments of the present invention, the cellulose is selected from at least one of methylcellulose, hydroxypropyl methylcellulose and sodium hydroxymethylcellulose.

[0062] According to some embodiments of the present invention, the polymer is selected from at least one of polyethylene microspheres, polystyrene, polyvinyl alcohol, and polyethylene glycol.

[0063] According to some embodiments of the present invention, the temperature of the first drying is 60-120°C, and the time is 8-24 hours.

[0064] According to some embodiments of the present invention, the temperature of the first calcination is 350-600℃, preferably 420-520℃; the pressure is 2-5MPa, preferably 3-4MPa; and the time is 4-20 hours, preferably 6-10 hours.

[0065] According to some embodiments of the present invention, the atmosphere for high-pressure calcination of the catalyst precursor during tableting is selected from at least one of inert gas, nitrogen, air, and oxygen.

[0066] According to some embodiments of the present invention, the oxygen content in the atmosphere is 0-40 wt%, preferably 15-25 wt%.

[0067] According to some embodiments of the present invention, the Na compound is selected from at least one of sodium carbonates, halides, acetates, citrates, and organic compounds.

[0068] According to some embodiments of the present invention, the Mg compound is selected from at least one of magnesium carbonates, halides, acetates, citrates, and organic compounds.

[0069] According to some embodiments of the present invention, the modified component is loaded in the form of a solution containing a precursor of the modified component, and the loading method is impregnation.

[0070] According to some embodiments of the present invention, the precursor of the modified component is selected from at least one of the halides, nitrates, acetates, carbonates, sulfates, hydroxides, ammonides, and organometallic compounds of the modified component.

[0071] According to some preferred embodiments of the present invention, the modified component is selected from at least one of the elements K, Ca, Ga, In, Fe, Mn, Re, Co, Pb, Zr, Mo and W.

[0072] According to some embodiments of the present invention, the temperature of the second drying is 60-160°C.

[0073] According to some embodiments of the present invention, the temperature of the second calcination is 350-600°C.

[0074] According to some embodiments of the present invention, the atmosphere for the second calcination is selected from at least one of an inert gas, nitrogen, and air.

[0075] According to the present invention, the preparation method of the above-mentioned desulfurization catalyst adopts tableting and impregnation technology, but is not limited to the above-mentioned method.

[0076] According to some embodiments of the present invention, the propane is derived from the bottom feed of a propylene distillation column; wherein the mass content of propane is greater than 99 wt% and the mass content of propylene is less than 1 wt%.

[0077] According to some embodiments of the present invention, the propylene-rich stream originates from at least one of the top of the depropanizer and the bottom of the deethanizer in a crude oil direct cracking process.

[0078] According to some embodiments of the present invention, the propylene-rich stream contains sulfur-containing compounds; the total sulfur molar content of the sulfur-containing compounds, calculated as elemental sulfur, is 1-100 ppm, preferably 20-50 ppm.

[0079] According to some embodiments of the present invention, the sulfur-containing compound is selected from at least one of carbonyl sulfide, carbon disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan, and propanethiol.

[0080] According to some embodiments of the present invention, the total sulfur molar content of dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan and propanethiol, calculated as elemental sulfur, is 0-60 ppm, preferably 5-30 ppm.

[0081] According to some embodiments of the present invention, the propylene-rich stream also contains at least one of propane, propylene, methyl acetylene (MA), propylene (PD), and C4 fraction.

[0082] According to some embodiments of the present invention, in the propylene-rich stream, the molar content of propylene is 80-95 mol, the total molar content of methyl acetylene and propadiene (MAPD) ​​is 1-7 mol, the total molar content of propane is 2-20 mol, the molar content of C4 fraction is 0.001-2.0 mol, and the molar content of C2 fraction is less than 0.1 mol.

[0083] According to some embodiments of the present invention, the conditions for the desulfurization treatment include: a temperature of 10-80°C, preferably 30-50°C; a pressure of 0.4-5 MPa, preferably 1.5-3 MPa; and a liquid hourly space velocity of 5-80 h⁻¹. -1 Preferably 20-40h -1 .

[0084] According to some embodiments of the present invention, the conditions for the regeneration treatment include: a temperature of 150-250°C, preferably 190-230°C; a time of 4-48 hours, preferably 8-24 hours; and a circulating ethane space velocity of 100-2000 h⁻¹. -1 Preferably 200-800h -1 .

[0085] According to some embodiments of the present invention, the mass content of the sulfur-containing compounds removed after the regeneration treatment in the regeneration gas is less than 1000 ppm, preferably less than 800 ppm, and more preferably less than 500 ppm.

[0086] According to the present invention, the sulfur content control obtained by the regeneration process is achieved by adjusting the flow rate of propane containing 5-10 vol% hydrogen.

[0087] According to some embodiments of the present invention, the method further includes: cracking the sulfur-containing compound obtained after the regeneration treatment in a light hydrocarbon cracking furnace, and then absorbing the hydrogen sulfide and sulfur dioxide generated by the cracking in an alkaline washing tower.

[0088] This invention employs a propane stream containing 5-10 vol% hydrogen to regenerate a desulfurization catalyst. The regeneration medium is a recycled propane stream containing 5-10 vol% hydrogen, used at a relatively high temperature to remove sulfur-containing compounds adsorbed on the catalyst. The resulting sulfur compounds are fed into a light hydrocarbon cracking furnace, where they are cracked into hydrogen sulfide and sulfur dioxide, which are then absorbed in an alkaline scrubbing tower along with the cracked gas. This regeneration process achieves trace sulfur removal and regeneration of the desulfurization catalyst for repeated use.

[0089] The sulfur-containing compounds obtained after regeneration are fed into a light hydrocarbon cracking furnace along with the circulating propane regeneration gas for cracking; the regeneration temperature of the desulfurization catalyst is 150-250℃.

[0090] According to some embodiments of the present invention, the sulfur-containing compound obtained after the regeneration treatment is selected from at least one of hydrogen sulfide, carbonyl sulfide, carbon disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan, propanethiol, tert-butanethiol, butanethiol, thiophene, and tetrahydrothiophene.

[0091] According to some embodiments of the present invention, the total sulfur molar content of the sulfur-containing compounds after the removal treatment of the propylene-rich stream is less than 1 ppm, calculated as elemental sulfur.

[0092] According to the present invention, the total sulfur molar content of sulfur-containing compounds before and after desulfurization treatment refers to the sulfur element content at the reactor inlet and outlet and the sulfur element content at the outlet, respectively.

[0093] like Figure 1 The diagram shows a desulfurization reaction process for a propylene-rich stream obtained from direct cracking of crude oil according to one embodiment of the present invention. The material 1 collected from the top of the deethaner I is heated by heat exchanger II before the desulfurization reactor, and the resulting inlet material 2 enters the desulfurization reactor III for desulfurization reaction. The resulting outlet material 3 is heated by heat exchanger IV before the C2 hydrogenation reactor, and the resulting inlet material 4 is mixed with hydrogen 5 and enters the C2 hydrogenation reactor V for hydrogenation reaction, resulting in the outlet material 6 of the C2 hydrogenation reactor.

[0094] like Figure 2 The diagram shows a regeneration process of a desulfurization catalyst according to one embodiment of the present invention. A portion of the recycled ethane material 11 from the ethylene distillation tower A is heated by heater B, and the resulting regenerated gas (recycled ethane) 13 enters the desulfurization reactor to regenerate the desulfurization catalyst. The regenerated sulfur-containing recycled ethane 14 is then heated by heat exchanger D and mixed with the remaining recycled ethane material 11' from the ethylene distillation tower A to form sulfur-containing ethane cracking feedstock 15. This feedstock then enters the light hydrocarbon cracking furnace E for cracking, and the resulting cracked gas 16 enters the alkaline washing tower F, ultimately forming alkaline-washed cracked gas 17. Before regeneration, nitrogen 12 is used to purge the existing cracked gas in the reactor to ensure that there is no residual cracked gas in the reactor.

[0095] The method of this invention can effectively remove sulfur-containing compounds in the direct cracking of crude oil to propylene process. It has the advantages of low operating temperature, no introduction of additional reactions, and repeated use of catalyst by regeneration with circulating propane containing 5-10 vol% hydrogen. The regenerated sulfides can be collected by alkaline washing, without environmental pollution problems, and ensures the long-term stable operation of the crude oil cracking unit.

[0096] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0097] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0098] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0099] Unless otherwise specified, the reagents used in the examples and comparative examples are all conventionally used reagents in the art, and the methods used are all conventional methods in the art.

[0100] The pseudoboehmite powder used below was purchased from Sinopec Catalysts (Beijing) Co., Ltd., with a specific surface area of ​​270 m². 2 / g or more.

[0101] The content of each element in the following carrier and catalyst was determined by ICP spectroscopy.

[0102] Preparation Example

[0103] Dissolve 100g of silver nitrate in 200ml of deionized water. Dissolve 150g of ammonium perrhenate in 500ml of deionized water. Under stirring at 40℃, slowly add the silver nitrate aqueous solution, producing a white precipitate. After all the solution has been added, let it stand for 30 minutes, then stop adding and cool to room temperature. Remove the filtrate, wash the white precipitate three times with ether, and dry it under vacuum at 80℃ to obtain silver perrhenate.

[0104] Example 1

[0105] 1) Weigh 80g of pseudoboehmite powder, silver perrhenate containing 2g Ag, cerium carbon nitrate containing 18g Ce, 4g of methylcellulose, and 1g of polyethylene microspheres, and mix them in a mixer to obtain a uniform powdered raw material.

[0106] 2) Weigh out sodium carbonate containing 10g Na and add it to 45g deionized water to prepare an aqueous solution containing Na; weigh out magnesium nitrate containing 5g Mg and add it to 45g deionized water to prepare an aqueous solution containing Mg.

[0107] 3) The uniform powdered raw material is transferred to a kneader, and aqueous solutions containing Na and Mg are slowly added. After kneading for 20 minutes, the mixture is pressed into tablets to obtain cylindrical particles with a particle size of 5 mm. The tablets are dried at 110 °C for 16 h and calcined at 370 °C for 4 h under an air atmosphere at a pressure of 3 MPa to obtain the catalyst precursor.

[0108] 4) Prepare 80 mL of an aqueous solution containing 1.5 g Ga of gallium nitrate. Immerse the catalyst precursor in this solution and dry it at 120 °C for 12 h to obtain the catalyst precursor. Calcinate the precursor at 450 °C for 12 h to obtain the catalyst, denoted as A-1. The catalyst contains, by total weight, 10 wt% Na, 5 wt% Mg, 1.5 wt% Ga, 2 wt% Ag, 3.5 wt% Re, and 18 wt% Ce.

[0109] Example 2

[0110] 1) Prepare the catalyst precursor according to steps 1)-3) in Example 1;

[0111] 2) Prepare 90 mL of an aqueous solution containing 1.5 g of indium nitrate (In). Immerse the catalyst precursor in this solution, dry at 105 °C for 8 h, and calcine at 460 °C for 8 h to obtain the catalyst, denoted as A-2. The catalyst contains, by total weight, 10 wt% Na, 5 wt% Mg, 1.5 wt% In, 2 wt% Ag, 3.5 wt% Re, and 18 wt% Ce.

[0112] Example 3

[0113] 1) Weigh 80g of boehmite powder, silver nitrate containing 5g Ag, lanthanum nitrate containing 25g La, sodium carboxymethyl cellulose, and 1g of polystyrene, and mix them in a mixer to obtain a uniform powdered raw material.

[0114] 2) Weigh out 6g of sodium fluoride containing Na, add it to 50g of deionized water to prepare an aqueous solution containing Na; weigh out 4g of magnesium nitrate containing Mg, add it to 40g of deionized water to prepare an aqueous solution containing Mg.

[0115] 3) The uniform powdered raw material was transferred to a kneader, and aqueous solutions containing Na and Mg were slowly added. After kneading for 20 minutes, the mixture was pressed into tablets to obtain cylindrical particles with a particle size of 4.5 mm. The tablets were dried at 120 °C for 8 hours and then calcined at 440 °C for 3 hours in a nitrogen-oxygen mixed atmosphere with a pressure of 2.6 MPa and an oxygen content of 35% to obtain the catalyst precursor.

[0116] 4) Prepare 70 mL of an aqueous solution containing 1 g of potassium carbonate (K). Immerse the catalyst precursor in this solution, dry at 105 °C for 6 h, and calcine at 320 °C for 4 h to obtain the catalyst, denoted as A-3. The catalyst contains, by total weight, 6 wt% Na, 4 wt% Mg, 4 wt% K, 5 wt% Ag, and 25 wt% La.

[0117] Example 4

[0118] 1) Prepare the catalyst precursor according to steps 1)-3) in Example 3;

[0119] 2) Prepare 70 mL of an aqueous solution containing 4 g of Li in lithium hydroxide. Immerse the catalyst precursor in this solution, dry at 140 °C for 4 h, and calcine at 430 °C for 8 h to obtain the catalyst, denoted as A-4. The catalyst contains, by total weight, 6 wt% Na, 4 wt% Mg, 4 wt% Li, 5 wt% Ag, and 25 wt% La.

[0120] Example 5

[0121] 1) Weigh 84g of boehmite powder, silver oxide containing 1g of Ag, yttrium nitrate containing 16g of Y, 8g of hydroxypropyl methylcellulose, and 2g of polyvinyl alcohol, and mix them in a mixer to obtain a uniform powdered raw material.

[0122] 2) Weigh out sodium nitrate containing 12g Na and magnesium nitrate containing 7g Mg, add them to 80g of deionized water, and prepare an aqueous solution containing Na and Mg.

[0123] 3) The uniform powdered raw material is transferred into a kneader and the acidic aqueous solution is slowly added. After kneading for 2 hours, it is extruded and granulated to obtain columnar carrier particles with a particle size of 5 mm. It is dried at 110℃ for 8 hours and calcined at 420℃ for 6 hours under a nitrogen-oxygen mixed atmosphere with a pressure of 2 MPa and an oxygen content of 14% to obtain the catalyst precursor.

[0124] 4) Prepare 90 mL of an aqueous solution of ferric nitrate containing 3 g of Fe. Immerse the catalyst precursor in this solution, dry at 130 °C for 4 h, and calcine at 400 °C for 6 h to obtain the catalyst, denoted as A-5. The catalyst contains, by total weight, 12 wt% Na, 7 wt% Mg, 3 wt% Fe, 1 wt% Ag, and 16 wt% Y.

[0125] Example 6

[0126] 1) Weigh 100g of pseudoboehmite powder, silver nitrate containing 4.5g Ag, scandium oxide containing 20g Sc, 5g of methylcellulose, and 3g of polyethylene microspheres, and mix them in a mixer to obtain a uniform powdered raw material.

[0127] 2) Weigh out 4g of sodium chloride containing Na and 3g of magnesium chloride containing Mg, add them to 75g of deionized water, and prepare an aqueous solution containing Na and Mg.

[0128] 3) The uniform powdered raw material is transferred into a kneader and the acidic aqueous solution is slowly added. After kneading for 2 hours, it is extruded and granulated to obtain columnar carrier particles with a particle size of 5.5 mm. It is dried at 105℃ for 8 hours and calcined at 500℃ for 6 hours under an air atmosphere at a pressure of 4 MPa to obtain the catalyst precursor.

[0129] 4) Prepare 80 mL of an aqueous solution containing 0.5 g Ca of calcium bicarbonate. Immerse the catalyst precursor in this solution, dry at 105 °C for 8 h, and calcine at 400 °C for 6 h to obtain the catalyst, denoted as A-6. The catalyst contains, by total weight, 4 wt% Na, 3 wt% Mg, 0.5 wt% Ca, 4.5 wt% Ag, and 20 wt% Sc.

[0130] Comparative Example 1

[0131] 1) Weigh 131 g of boehmite powder, 5 g of guar gum powder, and 5 g of starch, and mix them in a mixer to obtain a uniform powdered raw material.

[0132] 2) Weigh 3g of concentrated nitric acid and add it to 100g of deionized water to prepare an acidic aqueous solution;

[0133] 3) The uniform powdered raw material is transferred into a kneader and the acidic aqueous solution is slowly added. After kneading for 2 hours, it is extruded and granulated to obtain columnar carrier particles with a particle size of 5 mm. It is dried at 120℃ for 8 hours and calcined at 550℃ for 6 hours under normal pressure and air atmosphere to obtain Al2O3 carrier.

[0134] 4) Prepare 90 mL of an aqueous solution containing 2 g AgNO3 and 10 g Na. Impregnate the obtained Al2O3 support in this solution, dry at 120 °C for 8 h, and calcine at 440 °C for 12 h to obtain the catalyst, denoted as D-1. The total weight of the catalyst contains 10 wt% Na and 2 wt% Ag.

[0135] Test Example 1

[0136] This test case illustrates the evaluation of the desulfurization catalyst's effect on sulfur removal from propylene-rich streams.

[0137] The trace sulfur removal process from the overhead stream of the propane stripper utilizes a single-stage liquid-phase fixed-bed reactor. Space velocity: 40 h⁻¹ -1 Pressure 2.3MPa, reactor inlet temperature 30-45℃.

[0138] Table 1 Composition and content of C4 fraction

[0139] composition Content (mol%) propylene 92.447 propane 4.085 MA 1.808 PD 1.456 C2 0.042 C4 0.078 carbonyl sulfide 25ppm Carbon disulfide 5ppm Methanethiol 7ppm Ethyl mercaptan 5ppm

[0140] The operating cycle refers to the time the system can operate while maintaining the total sulfur content at the reactor outlet below 1 ppm. The total sulfur content refers to the total molar content of sulfur-containing compounds in the material, expressed as elemental sulfur.

[0141] Table 2 Comparison of desulfurization performance of various catalysts

[0142]

[0143] Table 1 shows a comparison of the desulfurization capabilities of different catalysts for sulfur-containing crude oil cracking gas streams. It can be seen that, while ensuring the total outlet concentration is less than 1 ppm, the operating cycles of each catalyst are different; compared to the comparative examples, the desulfurization catalysts prepared in Examples 1-6 have longer operating times, lower reaction temperatures, and no reaction temperature rise.

[0144] Test Example 2

[0145] This test case is used to illustrate the evaluation of the sulfur removal effect of the desulfurization catalyst on the cracked gas stream after repeated regeneration.

[0146] A single-stage liquid-phase fixed-bed reactor was used, with a liquid space velocity of 20 h⁻¹. -1 Other process conditions, sulfur content, and material composition are the same as in Test 1.

[0147] The regeneration medium is propane gas containing 8 vol% hydrogen, the heating rate is 50℃ / h to 220℃, the regeneration time is 15 hours, and the propane regeneration space velocity is 500 h⁻¹.

[0148] Each catalyst is switched off for regeneration after running online for 48 hours each time, and then switched back into operation, and this process is repeated.

[0149] Table 3 Comparison of the maximum number of regeneration cycles for each catalyst to achieve acceptable total sulfur content at the outlet.

[0150]

[0151]

[0152] Table 2 presents a comparison of the number of times the catalysts can be repeatedly regenerated. Experiments show that, compared to the comparative example, the number of regeneration cycles for each catalyst is significantly increased, and they still maintain excellent sulfur removal and purification capabilities after regeneration, resulting in a substantial extension of catalyst lifespan.

[0153] Test Example 3

[0154] This test case illustrates the comparison of sulfides after regeneration of desulfurization catalysts under different media conditions.

[0155] A single-stage adiabatic liquid bed reactor was used, with a liquid space velocity of 1 h⁻¹. -1 Other process conditions, sulfur content, and material composition are the same as in Test 1.

[0156] Regeneration 1: The medium is propane gas containing 8 vol% hydrogen, the heating rate is 50℃ / h to 220℃, the regeneration time is 15 hours, and the propane regeneration space velocity is 500 h⁻¹. -1 .

[0157] Regeneration 2: The medium is propane gas containing 10 vol% hydrogen, the heating rate is 50℃ / h to 240℃, the regeneration time is 15 hours, and the propane regeneration space velocity is 100 h⁻¹. -1 .

[0158] Regeneration 3: The medium is propane gas containing 5 vol% hydrogen (containing 1000 ppm propylene), the heating rate is 50℃ / h to 190℃, the regeneration time is 15 hours, and the propane regeneration space velocity is 500 h⁻¹. -1 .

[0159] Comparison 1: The medium is nitrogen, the heating rate is 50℃ / h, reaching 240℃, the regeneration time is 15 hours, and the regeneration space velocity is 100h. -1 .

[0160] Comparison 2: The medium is pure propane gas, the heating rate is 50℃ / h, reaching 240℃, the regeneration time is 15 hours, and the propane regeneration space velocity is 50h⁻¹. -1 .

[0161] Table 4. Sulfur distribution and maximum peak content at the regeneration outlet of catalyst A-1 under different regeneration methods.

[0162]

[0163]

[0164] The experimental results in Table 3 show that hydrogen and propane, as regeneration gases, can remove sulfur adsorbed on the catalyst surface at high temperatures. The sulfur-containing compounds are then completely converted into hydrogen sulfide through cracking. Alkali washing can effectively recover the regenerated sulfur, meeting environmental protection requirements. The peak sulfur content varies depending on the space velocity and temperature. When the regeneration gas space velocity is low, the regenerated sulfur cannot be completely recovered in the alkaline washing tower. Nitrogen regeneration cannot enter the cracking system, thus preventing complete sulfur recovery and causing environmental pollution.

[0165] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A desulfurization method for propylene-rich streams, characterized in that, The desulfurization method includes: (1) In a liquid-phase fixed-bed reactor, a propylene-rich stream is contacted with a desulfurization catalyst for desulfurization treatment; wherein the desulfurization catalyst contains Al2O3, Na, Mg, Ag and rare earth metals; (2) Use propane containing 5-10 vol% hydrogen as regeneration gas to regenerate the desulfurization catalyst after use.

2. The desulfurization method according to claim 1, wherein, Based on the total weight of the desulfurization catalyst, the weight content of Na is 2-15 wt%, preferably 5-10 wt%; the weight content of Mg is 2-8 wt%, preferably 4-6 wt%; the weight content of Ag is 0.5-5 wt%, preferably 1-3 wt%; and the weight content of rare earth metals is 15-30 wt%, preferably 18-25 wt%.

3. The desulfurization method according to claim 1 or 2, wherein, The rare earth metal is selected from at least one of La, Ce, Pr, Nd, Sm, Yb, Lu, Sc and Y; Preferably, the rare earth metal is selected from at least one of La, Ce, Pr, Lu, Sc and Y.

4. The desulfurization method according to any one of claims 1-3, wherein, The desulfurization catalyst further contains a modifying component; the modifying component is selected from at least one of K, Ca, Ga, In, Zn, Mn, Re, Au, Group VIII elements, Group IB elements, Group IVA elements, Group IVB elements, Group VA elements, and Group VIB elements; Preferably, the modifying component is selected from at least one of the elements K, Ca, Ga, In, Fe, Mn, Re, Co, Pb, Zr, Mo and W.

5. The desulfurization method according to claim 4, wherein, The modified component has a weight content of <10 wt%, preferably 0.5-5 wt%, based on the total weight of the desulfurization catalyst.

6. The desulfurization method according to any one of claims 1-5, wherein, The desulfurization catalyst also contains Al(OH)3; Preferably, based on the total weight of Al2O3 and Al(OH)3, the weight content of the γ phase in the Al2O3 crystal form is >80%, and the weight content of Al(OH)3 is <10wt%.

7. The desulfurization method according to any one of claims 1-6, wherein, The specific surface area of ​​the desulfurization catalyst is 100-500 m². 2 / g, preferably 180-400m 2 / g, more preferably 200-300m 2 / g.

8. The desulfurization method according to any one of claims 1-7, wherein, The propane is derived from the bottom feed of a propylene distillation column; wherein the mass content of propane is greater than 99 wt% and the mass content of propylene is less than 1 wt%. And / or, the propylene-rich stream originates from at least one of the top of the depropanizer and the bottom of the deethanizer in a crude oil direct cracking process.

9. The desulfurization method according to any one of claims 1-8, wherein, The propylene-rich stream contains sulfur-containing compounds; the total sulfur molar content of the sulfur-containing compounds, calculated as elemental sulfur, is 1-100 ppm, preferably 20-50 ppm. Preferably, the sulfur-containing compound is selected from at least one of carbonyl sulfide, carbon disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan, and propanethiol; More preferably, the total sulfur molar content of dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan and propanethiol, calculated as elemental sulfur, is 0-60 ppm, preferably 5-30 ppm.

10. The desulfurization method according to claim 9, wherein, The propylene-rich stream also contains at least one of propane, propylene, methylacetylene, propadiene, and C4 fraction; Preferably, in the propylene-rich stream, the molar content of propylene is 80-95 mol, the total molar content of methylacetylene and propadiene is 1-7 mol, the total molar content of propane is 2-20 mol, the molar content of C4 fraction is 0.001-2.0 mol, and the molar content of C2 fraction is less than 0.1 mol.

11. The desulfurization method according to any one of claims 1-10, wherein, The desulfurization conditions include: a temperature of 10-80℃, preferably 30-50℃; a pressure of 0.4-5MPa, preferably 1.5-3MPa; and a liquid hourly space velocity of 5-80 h⁻¹. -1 Preferably 20-40h -1 .

12. The desulfurization method according to any one of claims 1-11, wherein, The regeneration conditions include: a temperature of 150-250℃, preferably 190-230℃; a time of 4-48 hours, preferably 8-24 hours; and a circulating ethane space velocity of 100-2000 h⁻¹. -1 Preferably 200-800h -1 .

13. The desulfurization method according to any one of claims 1-12, wherein, The mass content of sulfur compounds removed after the regeneration treatment in the regeneration gas is less than 1000 ppm, preferably less than 800 ppm, and more preferably less than 500 ppm.

14. The desulfurization method according to any one of claims 1-13, wherein, The method further includes: cracking the sulfur-containing compound obtained after the regeneration treatment in a light hydrocarbon cracking furnace, and then absorbing the hydrogen sulfide and sulfur dioxide produced by the cracking in an alkaline washing tower. Preferably, the sulfur-containing compound obtained after the regeneration treatment is selected from at least one of hydrogen sulfide, carbonyl sulfide, carbon disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, methanethiol, ethyl mercaptan, propanethiol, tert-butanethiol, butanethiol, thiophene, and tetrahydrothiophene.

15. The desulfurization method according to any one of claims 1-14, wherein, The total sulfur molar content of the sulfur-containing compounds in the propylene-rich stream after desulfurization treatment is less than 1 ppm, calculated as elemental sulfur.

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