Deep desulfurization controllable modified porous composite adsorbent and preparation method thereof

Abstract

The present application belongs to the technical field of desulfurization adsorbent preparation, and particularly relates to a porous composite adsorbent with controllable modification for deep desulfurization and a preparation method thereof. The preparation method of the porous composite adsorbent is as follows: first, prepare a molecular sieve raw powder, then exchange the molecular sieve raw powder with ammonium salt and potassium salt to prepare a modified molecular sieve; impregnate the modified molecular sieve with an impregnation solution containing a metal nickel compound and a metal copper compound to obtain a modified molecular sieve loaded with active metals; modify alumina with organic zinc to obtain zinc-modified alumina; mix the modified molecular sieve loaded with active metals, the zinc-modified alumina, a binder and a pore-expanding agent uniformly, then knead and shape to obtain an adsorbent blank, and then sequentially perform drying, calcination, micro-activation, washing and reduction to obtain the porous composite adsorbent. The porous composite adsorbent prepared by the present application has a large specific surface area, high selectivity and high sulfur capacity, can reduce the content of organic sulfur such as thiophene to below 10 ppb, and has high activity after regeneration.

Description

Technical Field

[0001] This invention belongs to the field of desulfurization adsorbent preparation technology, specifically relating to a porous composite adsorbent with controllable modification for deep desulfurization and its preparation method. Background Technology

[0002] Petroleum fossil fuels generate large amounts of sulfides during industrial production, polluting the natural environment and harming human health. Therefore, it is necessary to remove sulfides from petroleum fossil fuels or their derivatives. Currently, common desulfurizing agents generally use porous materials such as molecular sieves and alumina as adsorbents, but these require loading with precious metals to achieve good desulfurization results. Furthermore, in traditional desulfurization processes, thiols, sulfides, and disulfides have simple structures and are easily removed, while thiophenes, benzothiophenes, dibenzothiophenes, and their derivatives are difficult to remove due to their aromatic structures and large steric hindrance.

[0003] Patent CN114433004A discloses a benzene desulfurizing agent, its preparation method, and its application. The method involves mixing 13X molecular sieve powder, potassium salt, and deionized water, followed by ion exchange treatment to obtain modified 13X molecular sieve. Then, 0.3-0.6% ruthenium is loaded onto the sieve, and it is kneaded with alumina to obtain the benzene desulfurizing agent. This desulfurizing agent can reduce the total sulfur content to below 10 ppb, exhibiting good desulfurization effect. However, ruthenium metal is expensive, resulting in a high cost for the desulfurizing agent.

[0004] Patent CN115770545A discloses a desulfurization adsorbent, its preparation method, and its application in deep benzene desulfurization. The method involves co-precipitating a mixed solution containing nickel and zinc with an alkaline salt solution, then adding an aluminum source solution and mixing. After processing under different conditions, a desulfurization adsorbent is obtained, wherein the nickel content is 20-60%, the zinc content is 3-10%, and the alumina content is 30-77%. This adsorbent has a space velocity of not less than 2 h⁻¹. -1 Under temperature conditions not exceeding 60℃, the effective sulfur capacity can exceed 1.0g thiophene / kg desulfurization adsorbent. Although it is not loaded with precious metals and the cost is reduced, the effective sulfur capacity is not high, and the service life or annual output will be reduced.

[0005] Currently, most desulfurization adsorbents on the market suffer from problems such as large particle size, limited increase in specific surface area and pore volume, inability to maximize the number of metal active sites, and high cost. This results in the need for long reaction times, large dosages, and high costs to achieve optimal desulfurization performance. Therefore, improving the performance of desulfurization adsorbents and reducing costs to obtain high-purity aromatic compounds is an urgent problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a porous composite adsorbent with controllable modification for deep desulfurization. This adsorbent has a large specific surface area, high selectivity, and high sulfur capacity, capable of reducing the content of organic sulfur compounds such as thiophene to below 10 ppb, and exhibits high activity after regeneration. The invention also provides a method for its preparation.

[0007] The preparation method of the deep desulfurization controllable modified porous composite adsorbent of the present invention includes the following steps:

[0008] (1) Aluminum source, silicon source, alkaline solution and mesoporous template agent are used to synthesize molecular sieve raw powder by hydrothermal method. The molecular sieve raw powder is then exchanged in a mixed solution of ammonium salt and potassium salt, and then dried and calcined to obtain modified molecular sieve.

[0009] (2) Disperse nickel and copper compounds in a dispersant to prepare an impregnation solution, and then impregnate the modified molecular sieve with the prepared impregnation solution to obtain a modified molecular sieve loaded with active metals.

[0010] (3) Aluminum source, acid source, organic zinc and precipitant are mixed to form a slurry, which is then aged, washed and dried to obtain zinc-modified alumina;

[0011] (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, binder, pore expander and deionized water evenly, and then knead them into shape to obtain the adsorbent blank;

[0012] (5) The adsorbent preform is successively dried, calcined, micro-activated, washed and reduced to obtain a porous composite adsorbent.

[0013] In step (1), when synthesizing molecular sieve raw powder, the mass ratio of the aluminum source, silicon source, alkaline solution and mesoporous template agent is 1:(1-150):(1-500):(0.01-20), preferably 1:(2-100):(5-300):(0.01-10).

[0014] The aluminum source is at least one of aluminum powder, sodium aluminate, aluminum trichloride, aluminum nitrate, and aluminum sulfate octadecahydrate.

[0015] The silicon source is at least one of silicon dioxide, silica, tetraethyl orthosilicate, and silica sol.

[0016] The alkaline solution is a sodium hydroxide solution, preferably with a concentration of 15-20 wt.%.

[0017] The mesoporous template agent is at least one of hexadecyltrimethylammonium bromide (CTAB), hexamethylammonium bromide (HMBr), hexadecyldimethyltrimethoxysilylpropylammonium chloride (TPHAC), P123, and F127.

[0018] In step (1), the molecular sieve raw powder can be synthesized using a conventional hydrothermal method. Specifically, the method is as follows:

[0019] Aluminate, silicon source, alkali solution, and mesoporous template agent are mixed and stirred until they form a white emulsion. Then, the mixture is placed in a polytetrafluoroethylene-lined reactor and crystallized for more than 48 hours to obtain molecular sieve raw powder.

[0020] In step (1), during the exchange, the mass ratio of the molecular sieve powder to ammonium salt, potassium salt and deionized water, based on the dry basis of the molecular sieve powder, is 1:(0.05-30):(0.1-25):(10-300), preferably 1:(0.1-20):(0.2-18):(20-250).

[0021] Wherein, the ammonium salt is at least one of ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium carbonate; the potassium salt is at least one of potassium chloride, potassium nitrate, potassium sulfate, and potassium carbonate; and during the exchange, the ammonium salt and potassium salt use the same anion type.

[0022] In step (1), the exchange temperature is 40-100℃ and the exchange time is 0.5-6h; preferably, the exchange temperature is 50-95℃ and the exchange time is 1-4h.

[0023] In step (1), the roasting temperature is 300-650℃ and the roasting time is 1-8h; preferably, the roasting temperature is 350-600℃ and the roasting time is 2-6h.

[0024] In step (1), the modified molecular sieve obtained is Y molecular sieve.

[0025] In step (2), the mass ratio of the nickel compound, copper compound and dispersant in the impregnation solution is 1:(0.1-2):(0.2-10), preferably 1:(0.5-1.5):(0.5-8).

[0026] The nickel compound is at least one of nickel nitrate, nickel oxide, nickel hydroxide, and nickel acetate.

[0027] The copper compound is at least one of copper nitrate, copper oxide, anhydrous copper sulfate, and copper chloride dihydrate;

[0028] The dispersant is at least one of anhydrous ethanol, methanol, formaldehyde, triethanolamine, and hydrochloric acid.

[0029] In step (2), the nickel and copper compounds are dispersed in a dispersant to form an impregnation solution by ultrasonic oscillation. The ultrasonic oscillation power is 30-200W and the time is 0.5-4h; preferably, the ultrasonic oscillation power is 50-150W and the time is 1-2h.

[0030] In step (2), the mass ratio of the modified molecular sieve to the impregnation solution is 1:(0.1-5), preferably 1:(0.2-3).

[0031] In step (2), the immersion temperature is 20-50℃ and the immersion time is 0.5-4h.

[0032] In step (3), the mass ratio of the aluminum source, acid source, organic zinc and precipitant in the slurry is 1:(0.05-15):(0.1-5):(0.01-5), preferably 1:(0.1-10):(0.2-2):(0.05-3).

[0033] The aluminum source is at least one of aluminum powder, sodium aluminate, aluminum trichloride, aluminum nitrate, and aluminum sulfate octadecahydrate.

[0034] The acid source is at least one of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and citric acid;

[0035] The organic zinc is at least one of diethyl zinc, dimethyl zinc, and zinc isooctanoate;

[0036] The precipitant is at least one of ammonia or urea.

[0037] In step (3), the aluminum source, acid source, organic zinc, and precipitant are mixed to form a slurry by stirring. The stirring rate is 30-550 rad / min, and the stirring time is 0.5-12 h; preferably, the stirring rate is 100-300 rad / min, and the stirring time is 2-10 h.

[0038] In step (3), the aging time is 0.5-4h, preferably 1-2h; the aging temperature is room temperature.

[0039] In step (3), at least one of deionized water, anhydrous ethanol, and anhydrous methanol is used for washing.

[0040] In step (3), the drying temperature is 50-150℃ and the drying time is 4-18h; preferably, the drying temperature is 80-135℃ and the drying time is 6-14h.

[0041] In step (4), the mass ratio of the modified molecular sieve loaded with active metal, zinc modified alumina, binder, pore expander and deionized water is (10-100):(1-25):(3-35):1:(5-100), preferably (15-90):(2-20):(5-30):1:(8-90).

[0042] The adhesive is at least one of kaolin, montmorillonite, and maifanite.

[0043] The pore-expanding agent is at least one of methylcellulose, ethylene oxide, and sodium alginate.

[0044] In step (5), the drying temperature is 70-200℃ and the drying time is 4-24h; preferably, the drying temperature is 80-180℃ and the drying time is 8-20h.

[0045] In step (5), the roasting temperature is 400-650℃ and the roasting time is 1-8h; preferably, the roasting temperature is 500-650℃ and the roasting time is 2-6h.

[0046] In step (5), the micro-activation solution used during micro-activation is at least one of ammonium carbonate solution, ammonium bicarbonate solution, ammonia solution, and sodium bicarbonate solution; the concentration of the micro-activation solution is 0.1-10 wt.%, preferably 0.2-5 wt.%. The micro-activation temperature is 10-50℃, and micro-activation is performed 1-5 times, each time for 10-90 min; preferably, the micro-activation temperature is 15-40℃, and micro-activation is performed 2-3 times, each time for 30-60 min.

[0047] In step (5), the washing is performed using a mixture of anhydrous ethanol and deionized water.

[0048] In step (5), the reducing atmosphere is 20-30% hydrogen gas introduced into argon gas, and the reducing conditions are a total space velocity of 100-400 h⁻¹. -1 The temperature is 350-680℃, and the time is 0.5-4h; preferably, the reduction conditions are a total space velocity of 200-300h. -1 Temperature 400-650℃, time 1-3h.

[0049] The porous composite adsorbent prepared by the above method has a specific surface area of ​​250-800 m². 2 / g, pore volume 0.5-1.2cm 3 / g, with an average pore size of 6-45nm and a bulk density of 0.35-0.85g / cm³. 3 The active components supported on it contain 0.01-15 wt.% Ni (in NiO form), 0.01-10 wt.% Cu, and 0.03-10 wt.% Zn.

[0050] Preferably, the porous composite adsorbent has a specific surface area of ​​300-750 m². 2 / g, pore volume 0.55-1.1cm 3 / g, with an average pore size of 10-38 nm and a bulk density of 0.4-0.7 g / cm³. 3 .

[0051] The porous composite adsorbent retains activity comparable to that of the fresh adsorbent after regeneration. The regeneration method is as follows:

[0052] The deactivated porous composite adsorbent was purged with pure nitrogen at 300℃ for 1 hour to remove residual hydrocarbon compounds. Then, the adsorbent was subjected to atmospheric pressure, 300℃, and a space velocity of 1000 h⁻¹. -1 A mixture of nitrogen and air with an oxygen content of 0.5% is introduced. When the sulfur content of the effluent is detected to be 10 ppm, the oxygen content is gradually increased to 1.0%, 1.5%, and 2.0%. After regeneration is completed, the temperature is lowered to obtain the regenerated porous composite adsorbent.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] (1) The porous composite adsorbent prepared by the present invention has an interlaced three-dimensional pore structure and a sheet structure, with a large specific surface area, high selectivity and high sulfur capacity.

[0055] (2) The porous composite adsorbent prepared by the present invention combines modified molecular sieve loaded with Ni and Cu active components with organic zinc modified alumina and lamellar porous materials. The addition of organic zinc can rely on the reaction of the mixture itself to generate small organic molecules that are wrapped by the slurry to form channels. Trace amounts of potassium can regulate the acidity of the molecular sieve and adsorbent, avoid excessive decomposition of sulfides, promote the bonding between active components and carrier, reduce carbon deposition, and improve the activity of adsorbent. At the same time, the adsorption process is accompanied by a combination of chemical adsorption and physical adsorption, maximizing the number of exposed active sites, promoting the removal of organic sulfides such as thiophene, achieving the effect of deep desulfurization, and reducing the content of organic sulfur such as thiophene to below 10 ppb.

[0056] (3) The porous composite adsorbent prepared by the present invention has a low regeneration temperature and simple regeneration conditions. After regeneration, it still has high activity compared with the fresh adsorbent. Attached Figure Description

[0057] Figure 1 The image shows the pore size distribution of the adsorbents prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0058] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the raw materials used in the embodiments are all commercially available conventional raw materials; unless otherwise specified, the process methods used in the embodiments are all conventional methods in the art.

[0059] Example 1

[0060] The porous composite adsorbent is prepared according to the method of the present invention, and the steps are as follows:

[0061] (1) Sodium aluminate, silica, sodium hydroxide solution (concentration 20wt.%), and hexadecyl dimethyltrimethoxysilylpropylammonium chloride were mixed and stirred evenly in a mass ratio of 1:3:5:0.3 until a white milky state was formed. Then, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized for 72 hours to obtain molecular sieve raw powder. Molecular sieve raw powder, ammonium chloride, potassium chloride, and deionized water were then exchanged at 80°C for 4 hours in a mass ratio of 1:1:2:35. After that, the mixture was dried at 100°C for 12 hours and calcined at 550°C for 6 hours to obtain modified molecular sieve.

[0062] (2) Nickel nitrate, copper nitrate, deionized water and anhydrous ethanol were mixed in a mass ratio of 1:0.5:1:0.5 and dispersed under ultrasonic conditions of 60W for 1 hour to prepare an impregnation solution. The modified molecular sieve was then impregnated with the prepared impregnation solution. The mass ratio of the modified molecular sieve to the impregnation solution was 1:1.5. The impregnation temperature was 40℃ and the impregnation time was 2 hours to obtain a modified molecular sieve loaded with active metal.

[0063] (3) Aluminum nitrate, nitric acid, diethylzinc and ammonia were mixed in a mass ratio of 1:2:1:1.5 and stirred for 6 hours at a stirring rate of 250 rad / min to form a slurry. After aging at room temperature for 2 hours, the slurry was washed with deionized water until neutral and dried at 100°C for 10 hours to obtain zinc-modified alumina.

[0064] (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, kaolin, montmorillonite, methylcellulose and deionized water in a mass ratio of 50:6:10:5:1:26 evenly, and then knead them into shape to obtain the adsorbent blank.

[0065] (5) The adsorbent preform was dried at 110℃ for 12 h, calcined at 450℃ for 4 h, activated three times with ammonium carbonate solution (concentration 2.5 wt.%, 30℃) for 30 min each time, and then washed 10 times with a mixture of anhydrous ethanol and deionized water (volume ratio 1:10, 70℃) for 30 min each time. After drying, 25% hydrogen gas was introduced into an argon atmosphere with a total space velocity of 250 h⁻¹. -1 The porous composite adsorbent was obtained by reducing it at 520℃ for 2 hours.

[0066] Example 2

[0067] The porous composite adsorbent is prepared according to the method of the present invention, and the steps are as follows:

[0068] (1) Sodium aluminate, silica sol, sodium hydroxide solution (concentration 15wt.%), and hexamethylammonium bromide were mixed and stirred evenly in a mass ratio of 1:2:5:0.01 until a white milky state was formed. Then, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized for 72 hours to obtain molecular sieve raw powder. Molecular sieve raw powder, ammonium carbonate, potassium carbonate, and deionized water were then exchanged at a mass ratio of 1:0.1:0.2:20 at 90℃ for 3 hours. After that, the mixture was dried at 100℃ for 12 hours and calcined at 600℃ for 2 hours to obtain modified molecular sieve.

[0069] (2) Nickel nitrate, anhydrous copper sulfate, deionized water and methanol were mixed in a mass ratio of 1:0.5:0.3:0.2 and dispersed under ultrasonic conditions of 60W for 1 hour to prepare an impregnation solution. The modified molecular sieve was then impregnated with the prepared impregnation solution. The mass ratio of the modified molecular sieve to the impregnation solution was 1:0.2. The impregnation temperature was 50℃ and the impregnation time was 0.5h to obtain a modified molecular sieve loaded with active metal.

[0070] (3) Aluminum nitrate, nitric acid, dimethyl zinc and ammonia water were mixed in a mass ratio of 1:0.1:0.2:0.05 and stirred at a stirring rate of 250 rad / min for 6 h to make a slurry. After aging at room temperature for 2 h, the slurry was washed with deionized water until neutral and dried at 100 °C for 10 h to obtain zinc modified alumina.

[0071] (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, kaolin, montmorillonite, sodium alginate and deionized water in a mass ratio of 15:2:1:4:1:8 and then knead them into shape to obtain the adsorbent blank.

[0072] (5) The adsorbent preform was dried at 150℃ for 8 hours, calcined at 550℃ for 3 hours, activated three times with ammonia solution (concentration 5.0 wt.%, 40℃) for 30 minutes each time, and then washed 10 times with a mixture of anhydrous ethanol and deionized water (volume ratio 1:10, 70℃) for 30 minutes each time. After drying, 20% hydrogen gas was introduced into an argon atmosphere with a total space velocity of 300 h⁻¹. -1 The porous composite adsorbent was obtained by reducing it at 550℃ for 2 hours.

[0073] Example 3

[0074] The porous composite adsorbent is prepared according to the method of the present invention, and the steps are as follows:

[0075] (1) Aluminum nitrate, silicon dioxide, sodium hydroxide solution (concentration 20wt.%), and P123 were mixed and stirred evenly in a mass ratio of 1:100:300:1 until a white milky state was formed. Then, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized for 60 hours to obtain molecular sieve raw powder. Molecular sieve raw powder, ammonium nitrate, potassium nitrate, and deionized water were then exchanged at 100℃ for 0.5 hours in a mass ratio of 1:10:5:60. After that, the mixture was dried at 100℃ for 12 hours and calcined at 650℃ for 1 hour to obtain modified molecular sieve.

[0076] (2) Nickel oxide, copper oxide, deionized water and anhydrous ethanol were mixed in a mass ratio of 1:1.5:4:4 and dispersed under ultrasonic conditions of 60W for 1 hour to prepare an impregnation solution. The modified molecular sieve was then impregnated with the prepared impregnation solution. The mass ratio of the modified molecular sieve to the impregnation solution was 1:3. The impregnation temperature was 20℃ and the impregnation time was 4 hours to obtain a modified molecular sieve loaded with active metal.

[0077] (3) Aluminum trichloride, hydrochloric acid, dimethyl zinc and urea were mixed in a mass ratio of 1:10:2:3 and stirred for 6 hours at a stirring rate of 250 rad / min to make a slurry. After aging at room temperature for 2 hours, the slurry was washed with deionized water until neutral and dried at 100°C for 10 hours to obtain zinc-modified alumina.

[0078] (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, kaolin, maifanite, sodium alginate and deionized water in a mass ratio of 90:20:10:20:1:90 evenly, and then knead them into shape to obtain the adsorbent blank.

[0079] (5) The adsorbent preform was dried at 70℃ for 24 h, calcined at 400℃ for 8 h, activated three times with ammonium bicarbonate solution (concentration 2.0 wt.%, 30℃) for 30 min each time, and then washed 10 times with a mixture of anhydrous ethanol and deionized water (volume ratio 1:10, 70℃) for 30 min each time. After drying, 30% hydrogen gas was introduced into an argon atmosphere with a total space velocity of 100 h⁻¹. -1 The porous composite adsorbent was obtained by reducing it at 350℃ for 4 hours.

[0080] Example 4

[0081] The porous composite adsorbent is prepared according to the method of the present invention, and the steps are as follows:

[0082] (1) Aluminum powder, silicon dioxide, sodium hydroxide solution (concentration 15wt.%), and hexadecyl dimethyltrimethoxysilylpropylammonium chloride were mixed and stirred evenly in a mass ratio of 1:50:100:10 until a white milky state was formed. Then, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized for 48 hours to obtain molecular sieve raw powder. Molecular sieve raw powder, ammonium nitrate, potassium nitrate and deionized water were then exchanged at 40℃ for 6 hours in a mass ratio of 1:20:18:250. After that, the mixture was dried at 100℃ for 12 hours and calcined at 300℃ for 8 hours to obtain modified molecular sieve.

[0083] (2) Nickel acetate, nickel nitrate, copper nitrate, deionized water and triethanolamine were mixed in a mass ratio of 0.5:0.5:1:2:1.5 and dispersed under ultrasonic conditions at a power of 60W for 1 hour to prepare an impregnation solution. The modified molecular sieve was then impregnated with the prepared impregnation solution. The mass ratio of the modified molecular sieve to the impregnation solution was 1:2. The impregnation temperature was 30℃ and the impregnation time was 3 hours to obtain a modified molecular sieve loaded with active metal.

[0084] (3) Sodium aluminate, aluminum nitrate, nitric acid, dimethyl zinc and urea were mixed in a mass ratio of 0.2:0.8:6:1:1.2 and stirred at a stirring rate of 250 rad / min for 6 h to make a slurry. After aging at room temperature for 2 h, the slurry was washed with deionized water until neutral and dried at 100 °C for 10 h to obtain zinc modified alumina.

[0085] (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, montmorillonite, maifanite, methylcellulose and deionized water in a mass ratio of 30:6:7:10:1:40, and then knead them into shape to obtain the adsorbent blank.

[0086] (5) The adsorbent preform was dried at 200℃ for 4 hours, calcined at 650℃ for 1 hour, activated three times with sodium bicarbonate (0.2 wt.%, 30℃) for 30 minutes each time, and then washed 10 times with a mixture of anhydrous ethanol and deionized water (volume ratio 1:10, 70℃) for 30 minutes each time. After drying, 25% hydrogen gas was introduced into an argon atmosphere with a total space velocity of 400 h⁻¹. -1 The porous composite adsorbent was obtained by reduction at 600℃ for 0.5 h.

[0087] Comparative Example 1

[0088] This comparative example does not involve the exchange modification of the molecular sieve powder. The only difference from Example 1 is that the molecular sieve powder prepared in step (1) is directly subjected to the operations in steps (2)-(5).

[0089] Comparative Example 2

[0090] This comparative example does not involve organozinc modification of alumina. The only difference from Example 1 is that step (3) is omitted, and an equal mass of alumina is used instead of the zinc-modified alumina in step (4).

[0091] Comparative Example 3

[0092] This comparative example only uses ammonium salt to exchange and modify the molecular sieve powder. The only difference from Example 1 is that potassium chloride is not added when exchanging and modifying the molecular sieve powder in step (1).

[0093] Comparative Example 4

[0094] This comparative example uses inorganic zinc instead of organic zinc to modify alumina. The only difference from Example 1 is that in step (3), diethyl zinc is replaced with zinc nitrate containing an equimolar amount of zinc.

[0095] Comparative Example 5

[0096] This comparative example uses calcium oxide instead of kaolin and montmorillonite as a binder. The only difference from Example 1 is that in step (4), an equal mass of calcium oxide is used instead of kaolin and montmorillonite.

[0097] Comparative Example 6

[0098] This comparative example uses only metallic nickel to load the modified molecular sieve, and the only difference from Example 1 is that copper nitrate is not added to the impregnation solution in step (2).

[0099] Comparative Example 7

[0100] This comparative example uses only metallic copper to load the modified molecular sieve, and the only difference from Example 1 is that nickel nitrate is not added to the impregnation solution in step (2).

[0101] The porous composite adsorbents prepared in each embodiment and comparative example were subjected to texture property testing, and the test results are shown in Table 1. Simultaneously, the pore size distribution of the porous composite adsorbents prepared in Example 1 and Comparative Example 1 was tested, and the results are shown in Table 1. Figure 1 As shown.

[0102] Table 1. Test results of the texture properties of porous composite adsorbents

[0103]

[0104] As shown in Table 1, compared with Example 1, the adsorbent prepared in Comparative Example 1 has a smaller pore volume and pore size, but a slightly larger specific surface area. This is because the molecular sieve was not modified for exchange, and the molecular sieve contains non-framework aluminum, which causes some blockage in some channels. The adsorbent prepared in Comparative Example 2 has a smaller specific surface area, pore volume, and pore size because the alumina was not modified with organozinc, and the pore structure in the alumina is not as rich as that of the alumina modified with organozinc. The pore volume and pore size of Comparative Example 3 are smaller, but the specific surface area is slightly larger. This is because the ammonium salt exchanges surface ions in the molecular sieve, and the entry into the channels is hindered due to the charge interaction between the ions, and the degree of exchange is not as good as in Example 1. The adsorbent prepared in Comparative Example 4 has a smaller pore volume and pore size, but a larger specific surface area. This is because the inorganic zinc cannot be effectively dispersed in the adsorbent and easily coats the surface of the alumina, causing aggregation between metal particles. The adsorbent prepared in Comparative Example 5 exhibits reduced specific surface area, pore volume, and pore size. This is because kaolinite's structure consists of SiO4 tetrahedral layers connected to AlO2(OH)4 octahedral layers. Montmorillonite has a similar structure to kaolinite and a similar material composition to molecular sieves, with more -OH groups and Si-O and Al-O bonds on its surface. Calcium oxide, being an ionic crystal, differs from molecular sieves in structure and composition, resulting in weaker inter-material bonding. Furthermore, montmorillonite and kaolinite have layered structures with richer pore structures. The adsorbent prepared in Comparative Example 6 shows reduced pore volume and pore size but increased specific surface area, indicating an interaction between metallic Ni and the pores, altering its structure and modifying its specific surface area. The adsorbent prepared in Comparative Example 7 also shows reduced specific surface area, pore volume, and pore size, suggesting that the addition of metallic Cu interacts with the pores, causing partial pore blockage.

[0105] from Figure 1 It can be seen that after the molecular sieve is modified, the pore size of the prepared adsorbent becomes larger, which is conducive to the diffusion of sulfides into the pores and improves the performance of the adsorbent. This indicates that the modified molecular sieve can remove some sodium ions and aluminum on the non-framework in the pores, and the change in pore structure increases the pore size while improving the performance of the catalyst.

[0106] The adsorption performance of the porous composite adsorbents prepared in each embodiment and comparative example was evaluated using the following methods:

[0107] A fixed-bed reactor was used, with 150g of porous composite adsorbent and 300g of alumina protective agent in the upper layer. The reaction temperature was controlled at 140-200℃, the reaction pressure at 0.4-1.0MPa, and the volume hourly space velocity at 1.0-3.5h⁻¹. -1 Collect the effluent, cool it to room temperature, and calculate the sulfur capacity.

[0108] The performance evaluation results of the adsorbent are shown in Table 2.

[0109] Table 2. Evaluation results of the adsorption performance of porous composite adsorbents

[0110]

[0111] As shown in Table 2, the porous composite adsorbent prepared by this invention, through modification of molecular sieves and loading of Ni and Cu active components, followed by modification of alumina with organic zinc, increases pore volume and pore size while maintaining a stable specific surface area. At the same time, the synergistic effect between zinc and metals Ni and Cu improves metal dispersion and significantly increases the number of active sites. Furthermore, potassium metal regulates the acidity of the adsorbent, reduces carbon deposition, and improves the activity and stability of the adsorbent. The porous composite adsorbent prepared by this invention has low cost and significant desulfurization effect.

[0112] Compared with Example 1, the molecular sieve in Comparative Example 1 was unmodified, resulting in low dispersion of the loaded metal active components, reduced active sites on the adsorbent surface, and poor desulfurization effect. In Comparative Example 2, the alumina was not modified with organic zinc, leading to a decrease in the specific surface area, pore volume, and pore size of the adsorbent. The distribution of active components on the adsorbent surface was uneven, resulting in low metal dispersion and poor desulfurization effect. In Comparative Example 3, only ammonium salt was used to exchange-modify the molecular sieve powder to obtain HY molecular sieve. However, the metal dispersion decreased, and without the regulation of acidity by metal K, the adsorbent deactivation rate accelerated, and the sulfur capacity decreased. In Comparative Example 4, after inorganic zinc was loaded with alumina, the pore volume and pore size of the prepared adsorbent decreased, the diffusion resistance of thiophene sulfur in the pores increased, the metal dispersion decreased, and deactivation was easier, resulting in a lower sulfur capacity. In Comparative Example 5, calcium oxide replaced kaolin and montmorillonite. Using desodium as a binder, the specific surface area, pore volume, and pore size of the prepared adsorbent are all reduced, the metal dispersion is decreased, and the number of metal active sites on the adsorbent surface is reduced. Therefore, the sulfur capacity result is still lower than that of Example 1. Comparative Example 6 only uses metallic nickel to load the modified molecular sieve. The single metal has limited control over the molecular sieve structure. The adsorbent does not contain metallic Cu active components. The metal pore volume and pore size are reduced, and the metal dispersion is smaller. Without the participation of metallic Cu, during the desulfurization evaluation process, metallic Ni and Zn on the adsorbent are prone to generating ZnS and NiS, which block the pores, reduce the number of active sites, and result in poor desulfurization effect. Comparative Example 7 only uses metallic copper to load the modified molecular sieve. The adsorbent lacks metallic Ni active components, has low metal dispersion, has limited adsorption capacity for thiophene sulfur, is easily deactivated, and has a small sulfur capacity.

[0113] In addition, to examine the regeneration performance of the porous composite adsorbents, the porous composite adsorbents prepared in the above examples and comparative examples were regenerated after adsorption performance evaluation. The regeneration conditions are as follows:

[0114] The deactivated adsorbent was purged with pure nitrogen at 300°C for 1 hour to remove residual hydrocarbon compounds. Subsequently, the adsorbent was purified at atmospheric pressure, 300°C, and a space velocity of 1000 h⁻¹. -1A mixture of nitrogen and air with an oxygen content of 0.5% is introduced. When the sulfur content of the effluent is detected to be 10 ppm, the oxygen content is gradually increased to 1.0%, 1.5%, and 2.0%. After regeneration is complete, the temperature is lowered.

[0115] After regeneration, the content of each active component in the regenerated adsorbent was measured, and the adsorption performance was evaluated again to calculate the sulfur capacity. The results of the regeneration performance evaluation are shown in Table 3.

[0116] Table 3. Evaluation results of the regeneration performance of porous composite adsorbents

[0117]

[0118]

[0119] As can be seen from Table 3, after the porous composite adsorbent prepared in this invention is regenerated, the active components are basically not lost. Compared with the fresh adsorbent, the changes in the metal active components are not significant, and the desulfurization effect is still good. This also indicates that the spatial structure of the regenerated adsorbent, such as the specific surface area, pore volume, and pore channels, has not changed.

[0120] Compared with Example 1, the adsorbent prepared in Comparative Example 1 showed that the content of each active component remained basically unchanged after regeneration, indicating that whether the molecular sieve was modified or not, the active components would not be lost due to catalyst deactivation and regeneration. However, since the molecular sieve was not modified, the adsorbent had relatively few active sites, and the dispersion and sulfur capacity were both small. The adsorbent prepared in Comparative Example 2 showed that the content of each active component remained basically unchanged after regeneration, indicating that since the alumina was not modified with organozinc, the active components would not be lost due to the lack of metallic Zn. Since the alumina was not modified with organozinc, the specific surface area, pore volume, and pore size of the adsorbent were reduced, the number of active sites decreased, and the metal dispersion and sulfur capacity were reduced. The adsorbent prepared in Comparative Example 3 was modified with ammonium salt only. After regeneration, the active components were basically not lost. However, the acidity of the adsorbent was too high, the deactivation rate was too fast during the evaluation process, the lifespan was short, and the sulfur capacity was low. The adsorbent prepared in Comparative Example 4 showed that after regeneration, the content of each active component remained basically unchanged. With stable component content, the pore size of the adsorbent decreased after inorganic zinc modification, hindering its adsorption capacity for thiophene molecules. Simultaneously, the metal dispersion also decreased, resulting in low sulfur capacity, and it was lower than that of the fresh adsorbent. In Comparative Example 5, the content of each active component remained stable after regeneration, but the addition of calcium oxide reduced the specific surface area and surface active sites, leading to decreased metal dispersion and sulfur capacity in the regenerated adsorbent, which was still lower than that of the fresh adsorbent. In Comparative Example 6, the content of each active component remained stable after regeneration. Without the participation of metallic Cu, sulfides easily accumulated on the adsorbent, clogging the pores, reducing active sites, lowering the metal dispersion, and resulting in poor sulfur capacity. In Comparative Example 7, the content of active components remained stable after regeneration, but the pore structure changed, resulting in low metal dispersion and a desulfurization effect inferior to Example 1 of this invention. Furthermore, the sulfur capacity tended to decrease after regeneration compared to the fresh adsorbent.

Claims

1. A method for preparing a porous composite adsorbent with controllable modification for deep desulfurization, characterized in that: Includes the following steps: (1) Aluminum source, silicon source, alkaline solution and mesoporous template agent are used to synthesize molecular sieve raw powder by hydrothermal method. The molecular sieve raw powder is then exchanged in a mixed solution of ammonium salt and potassium salt, followed by drying and calcination to obtain modified molecular sieve. (2) Disperse the nickel compound and copper compound in a dispersant to prepare an impregnation solution, and then impregnate the modified molecular sieve with the prepared impregnation solution to obtain a modified molecular sieve loaded with active metal; (3) Aluminum source, acid source, organic zinc and precipitant are mixed to form a slurry, which is then aged, washed and dried to obtain zinc-modified alumina; (4) Mix the modified molecular sieve loaded with active metal, zinc modified alumina, binder, pore expander and deionized water evenly, and then knead them into shape to obtain the adsorbent blank; (5) The adsorbent preform is successively dried, calcined, micro-activated, washed and reduced to obtain a porous composite adsorbent; In step (4), the adhesive is at least one of kaolin, montmorillonite, and maifanite; In step (5), the micro-activation is performed using a micro-activation solution; The micro-activation solution is at least one of ammonium carbonate solution, ammonium bicarbonate solution, ammonia solution, and sodium bicarbonate solution.

2. The preparation method of the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (1), when synthesizing molecular sieve powder, the mass ratio of the aluminum source, silicon source, alkaline solution and mesoporous template agent is 1:(1-150):(1-500):(0.01-20). The aluminum source is at least one of aluminum powder, sodium aluminate, aluminum trichloride, aluminum nitrate, and aluminum sulfate octadecahydrate. The silicon source is at least one of silicon dioxide, silica, tetraethyl orthosilicate, and silica sol. The alkaline solution is a sodium hydroxide solution; The mesoporous template agent is at least one of hexadecyltrimethylammonium bromide, hexamethylammonium bromide, hexadecyldimethyltrimethoxysilylpropylammonium chloride, P123, and F127.

3. The preparation method of the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (1), during the exchange, the mass ratio of the molecular sieve powder to ammonium salt, potassium salt and deionized water, based on the dry basis of the molecular sieve powder, is 1:(0.05-30):(0.1-25):(10-300). Wherein, the ammonium salt is at least one of ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium carbonate; the potassium salt is at least one of potassium chloride, potassium nitrate, potassium sulfate, and potassium carbonate; and during the exchange, the ammonium salt and potassium salt use the same anion type.

4. The preparation method of the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (1), the exchange temperature is 40-100℃ and the exchange time is 0.5-6h; the calcination temperature is 300-650℃ and the calcination time is 1-8h.

5. The method for preparing the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (2), the mass ratio of the nickel compound, copper compound, and dispersant in the impregnation solution is 1:(0.1-2):(0.2-10). The nickel compound is at least one of nickel nitrate, nickel oxide, nickel hydroxide, and nickel acetate. The metallic copper compound is at least one of copper nitrate, copper oxide, anhydrous copper sulfate, and copper chloride dihydrate; The dispersant is at least one of anhydrous ethanol, methanol, formaldehyde, triethanolamine, and hydrochloric acid.

6. The method for preparing the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (2), the mass ratio of the modified molecular sieve to the impregnation solution is 1:(0.1-5).

7. The method for preparing the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (3), the mass ratio of the aluminum source, acid source, organic zinc, and precipitant in the slurry is 1:(0.05-15):(0.1-5):(0.01-5). The aluminum source is at least one of aluminum powder, sodium aluminate, aluminum trichloride, aluminum nitrate, and aluminum sulfate octadecahydrate. The acid source is at least one of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and citric acid; The organic zinc is at least one of diethyl zinc, dimethyl zinc, and zinc isooctanoate; The precipitant is at least one of ammonia or urea.

8. The method for preparing the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (4), the mass ratio of the modified molecular sieve loaded with active metal, zinc-modified alumina, binder, pore expander and deionized water is (10-100):(1-25):(3-35):1:(5-100). The pore-expanding agent is at least one of methylcellulose, ethylene oxide, and sodium alginate.

9. The method for preparing the porous composite adsorbent with controllable modification for deep desulfurization according to claim 1, characterized in that: In step (5), the drying temperature is 70-200℃ and the drying time is 4-24h; The roasting temperature is 400-650℃, and the roasting time is 1-8 hours; The concentration of the micro-activation solution used during micro-activation is 0.1-10 wt.%. The reducing atmosphere consists of 20-30% hydrogen gas introduced into argon gas, and the reducing conditions are a total space velocity of 100-400 h⁻¹. -1 The temperature is 350-680℃, and the time is 0.5-4h.

10. A porous composite adsorbent with controllable modification for deep desulfurization prepared by the preparation method according to any one of claims 1-9, characterized in that: Specific surface area is 250-800 m² 2 / g, pore volume 0.5-1.2cm 3 / g, with an average pore size of 6-45nm and a bulk density of 0.35-0.85g / cm³. 3 The active components it supports contain 0.01-15 wt.% Ni, 0.01-10 wt.% Cu, and 0.03-10 wt.% Zn.

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