Spherical stepped-pore alumina, and preparation method and application thereof
By designing a stepped porous alumina, the problem of insufficient diffusion performance of the residue hydrotreating catalyst was solved, achieving efficient residue hydrotreating and extending the catalyst's service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SINOCHEM QUANZHOU PETROCHEM CO LTD
- Filing Date
- 2023-06-20
- Publication Date
- 2026-06-09
AI Technical Summary
Existing residue hydrotreating catalysts suffer from insufficient diffusion performance in their pore structure design, making it difficult for large molecular compounds to penetrate deep into the catalyst interior. Metals and coke easily clog the pore openings, leading to decreased catalyst activity and shortened service life.
Using stepped porous alumina as a catalyst support, the pore structure expands in a stepwise manner from the inside out, with macropores on the surface, mesopores in the middle layer, and micropores in the inner layer. By controlling the molding auxiliary materials and template agents, spherical alumina is prepared to ensure the diffusion and mass transfer of macromolecular compounds, while metals and carbon deposits are deposited inside.
It improves the diffusion performance of the catalyst, reduces orifice clogging, extends the service life of the catalyst, and enhances the efficiency and stability of residue hydrotreating.
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Figure CN116835621B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a spherical stepped porous alumina, its preparation method, and its application. Background Technology
[0002] As crude oil becomes increasingly heavy and of lower quality, and environmental regulations become more stringent, the use of hydrotreating technology to process residual oil can not only convert heavy oil into light oil products and improve crude oil utilization, but also reduce environmental pollution and meet environmental regulations. Therefore, residual oil hydrotreating technology has become the preferred technology for refining and chemical enterprises to process heavy oil.
[0003] Residue hydrotreating technologies generally include fixed-bed, moving-bed, fluidized-bed, and slurry-bed processes. Among these, fixed-bed residue hydrotreating technology has the highest maturity and is the most widely used. In fixed-bed residue hydrotreating technology, an upflow reactor (UFR) can be installed before the fixed-bed reactor to extend the unit's operating cycle. In the upflow reactor, the mixture of feedstock and hydrogen flows upward from the bottom of the reactor through the catalyst bed, causing the entire catalyst bed to be in a slightly expanded state. Therefore, the pressure drop in the reactor is small, and it can effectively remove impurities such as metals (mainly Ni and V), sulfur, and nitrogen from the feedstock, protecting the downstream fixed-bed catalyst and fully utilizing the overall catalyst performance, thereby extending the unit's operating cycle. It is generally believed that spherical catalysts with smaller particle sizes are more suitable for upflow residue hydrotreating.
[0004] Most metallic impurities in residual oil are found in macromolecular compounds such as asphaltenes and gums. These compounds have complex structures and large molecular sizes, making diffusion difficult within the catalyst channels. Therefore, residual oil hydrotreating is a typical internal diffusion-controlled process. Furthermore, coke and removed metals will deposit on the catalyst surface and within the channels. To prevent the deposited metals and coke from clogging the catalyst pores and causing rapid catalyst deactivation, upflow residual oil hydrotreating catalysts require excellent pore structures. The catalyst surface should have macropores to facilitate the diffusion and mass transfer of macromolecular compounds such as asphaltenes, while the interior should have a mesoporous structure to provide sufficient active surface area, thereby improving the catalyst's reactivity and extending its service life.
[0005] Patent CN 1665907A discloses an upflow hydrogenation catalyst whose support is composed of alumina with a pore volume of 0.6~1.1 mL / g and a specific surface area of 110~190 m². 2The catalyst has a pore size of approximately 0.1 inches (about 2.5 mm), with less than 35% having a diameter greater than 1000 angstroms and a peak pore size of 80–140 angstroms for nitrogen desorption. The catalyst is spherical or elliptical in shape. The average pore size is small, and compared to the catalyst prepared in US Patent 5472928, this catalyst exhibits higher hydrodesulfurization activity and lower hydrodemetallization activity. In heavy oil hydrotreating, the heavy feedstock is first contacted with the catalyst prepared according to US 5472928 under hydrodemetallization conditions, and then the product is contacted with this catalyst for hydrodesulfurization. While suitable as a hydrodesulfurization catalyst, it requires prior gradation with a hydrodemetallization catalyst to extend its lifespan; therefore, it is not suitable for use alone in an upflow reactor.
[0006] US Patent 4,448,896 discloses an alumina carrier with unobstructed pores and its preparation method. It uses boehmite as a raw material and carbon black powder as a pore-expanding agent, obtaining the alumina carrier through mixing, extrusion, drying, and calcination. Its drawback is that adding a small amount of carbon black powder easily forms "ink bottle" shaped pores, making it difficult to form unobstructed pores; adding too much carbon black powder significantly reduces the carrier's strength.
[0007] Patent CN 104646005A discloses a catalyst with an open "trumpet-shaped" pore structure and its preparation method. The catalyst support pores gradually increase in size from the particle center to the outer surface, with an average pore diameter of 19.0~30.0 nm. This method can alleviate the pore blockage problem to some extent, but the lack of large pores on the catalyst surface limits its improvement on catalyst diffusion performance, and large molecular reactants such as asphaltene still struggle to penetrate to the center of the catalyst particles. Summary of the Invention
[0008] To address the shortcomings of existing technologies, this invention provides a stepped porous alumina and its preparation method. This stepped porous alumina features large pore volume, large pore size, and pores that expand in a stepwise manner from the inside to the outside. At the same time, the surface of the stepped porous alumina contains a certain proportion of macroporous structures with a diameter of 100 nm or more, which gives it excellent diffusion performance. Therefore, it can be used as a catalyst support, especially as a catalyst support for upflow residue hydrotreating.
[0009] To achieve the above objectives, the present invention adopts the following technical solution:
[0010] A type of spherical, stepped-pore alumina, with a pore volume of 0.6–1.6 mL / g and a specific surface area of 80–250 m², determined by mercury porosimetry. 2 / g, the average pore diameter increases in a stepwise manner from the center of the sphere to the outer surface along the radial direction of the sphere. Specifically, the average pore diameter from the center of the sphere to a distance of 30-50% of the radius of the sphere is 10-25 nm; the average pore diameter from a distance of 30-50% of the radius of the sphere to a distance of 50-80% of the radius of the sphere is 20-40 nm; and the average pore diameter from a distance of 50-80% of the radius of the sphere to the outer surface of the sphere is 40-60 nm. The outer surface of the sphere contains macropores with a diameter of more than 100 nm, and the corresponding pore volume accounts for 20%-60% of the total pore volume.
[0011] The method for preparing the spherical stepped porous alumina includes the following steps:
[0012] (1) Mix boehmite PB-1 with molding auxiliary material evenly as powder A, mix boehmite PB-2 with molding auxiliary material evenly as powder B, and mix boehmite PB-2 with molding auxiliary material and template agent evenly as powder C.
[0013] (2) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder B is stopped. Then powder C is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the ball forming is completed.
[0014] (3) The obtained wet bulbs are cured, dried and calcined to obtain the spherical stepped porous alumina.
[0015] Furthermore, the pseudoboehmite PB-1 and PB-2 mentioned in step (1) can be commercially available products or products prepared by any method in the prior art, such as aluminum sulfate method, carbonization method, aluminum alkoxide hydrolysis method, hydrothermal method, etc.
[0016] Furthermore, the pseudoboehmite PB-1 has a pore volume of 0.8~1.2 mL / g and a specific surface area of 200~350 m². 2 / g, with a grain size d(120) of 8~20 nm; the pseudoboehmite PB-2 has a pore volume of 1.0~1.5 mL / g and a specific surface area of 80~200 m² / g. 2 / g, grain size d(120)≥25 nm.
[0017] Further, the molding auxiliary material mentioned in step (1) is selected from one or more of guar gum powder, starch, methylcellulose, polyacrylamide, and polycarboxylic acid, and its addition amount is 0.3~5% of the dry basis mass of the corresponding boehmite.
[0018] Further, the template agent in step (1) is one or more of the following high molecular polymer powders: polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, etc., and its addition amount is 5 to 30% of the dry basis mass of pseudoboehmite PB-2.
[0019] Further, the adhesive solvent mentioned in step (2) is a variety of adhesive solvents commonly used in the art. It can be aluminum sol and / or silica sol, or it can be an inorganic acid and / or organic acid solution. The mass concentration of the inorganic acid and / or organic acid is 2-20%. The inorganic acid can be one or more of nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid, preferably nitric acid. The organic acid can be one or more of oxalic acid, acetic acid, and citric acid.
[0020] Furthermore, the temperature for health preservation in step (3) is 10~40℃ and the time is 6~48 h.
[0021] Furthermore, the drying temperature in step (3) is 50~150 ℃ and the time is 1~24 h.
[0022] Furthermore, the roasting temperature in step (3) is 600~1000 ℃ and the time is 1~6 h.
[0023] The spherical stepped-pore alumina obtained above can be used as a catalyst support for residue hydrotreating, especially for upflow residue hydrotreating catalyst support.
[0024] The significant advantages of this invention are:
[0025] The alumina obtained in this invention exhibits a stepped pore structure. Its surface macroporous structure facilitates the diffusion and mass transfer of large molecular compounds, reducing surface-level reactions and preventing the removal of metals and carbon deposits from clogging the pore openings. The larger mesoporous structure in the middle layer effectively promotes the reaction process, allowing metals and carbon deposits to settle within the catalyst, while also facilitating the further diffusion of smaller compound molecules after metal removal into the inner layer. The smaller mesoporous structure in the inner layer has a large specific surface area, providing sufficient space for the reaction, and the product molecules can rapidly diffuse out due to the macroporous structure of the outer layer. Therefore, the alumina prepared by this invention exhibits excellent diffusion performance and is particularly suitable for use as a catalyst support in upflow residue hydrotreating.
[0026] The preparation method provided by this invention is simple, the process is concise, and the thickness of each layer can be flexibly adjusted and easily controlled, making it easy to apply in industry. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the radial pore size distribution of the spherical stepped porous alumina prepared in this invention. Detailed Implementation
[0028] A spherical stepped-pore alumina is prepared by the following steps:
[0029] (1) Mix boehmite PB-1 with molding auxiliary material evenly as powder A, mix boehmite PB-2 with molding auxiliary material evenly as powder B, and mix boehmite PB-2 with molding auxiliary material and template agent evenly as powder C.
[0030] (2) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder B is stopped. Then powder C is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the ball forming is completed.
[0031] (3) After the obtained wet bulbs are cured at 10~40℃ for 6~48 h, they are dried at 50~150℃ for 1~24 h, and then calcined at 600~1000℃ for 1~6 h to obtain the spherical stepped porous alumina.
[0032] In step (1), the molding auxiliary material is selected from one or more of guar gum powder, starch, methylcellulose, polyacrylamide, and polycarboxylic acids, and its addition amount is 0.3-5% of the dry basis mass of the corresponding boehmite. The template agent is one or more of high molecular polymer powders such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyurethane, and its addition amount is 5-30% of the dry basis mass of the boehmite PB-2.
[0033] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0034] Example 1
[0035] (1) Weigh 1000 g of pseudoboehmite PB-1 (pore volume of 1.0 mL / g, specific surface area of 220 m²) 2 / g, crystal size d(120) is 15 nm) and 25 g of guar gum powder, mix them evenly to obtain powder A; weigh 1000 g of pseudoboehmite PB-2 (pore volume is 1.2 mL / g, specific surface area is 120 m²) 2 / g, crystal size d(120) is 40 nm) and 25 g of guar gum powder, and mix them evenly to obtain powder B; weigh 1000 g of pseudoboehmite PB-2, 25 g of guar gum powder and 70 g of polyethylene powder, and mix them evenly to obtain powder C1.
[0036] (2) Add 20 g of citric acid and 35 g of nitric acid to 1000 g of water and stir to mix evenly to obtain peptide solvent P1.
[0037] (3) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent P1 to roll into balls. When the average wet ball size reaches 1.5 mm, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and the adhesive solvent P1 is sprayed to continue to form balls. When the average wet ball size reaches 3.0 mm, the feeding of powder B is stopped. Then powder C1 is fed into the sugar coating machine and the adhesive solvent P1 is sprayed to continue to form balls. When the average wet ball size reaches 4.0 mm, the ball forming is completed.
[0038] (4) The wet bulb was cured at room temperature for 24 h, then dried at 80 ℃ for 6 h, and finally calcined at 650 ℃ for 4 h to obtain alumina sample S1.
[0039] Example 2
[0040] (1) Weigh 1000 g of pseudoboehmite PB-1 (pore volume of 1.0 mL / g, specific surface area of 220 m²) 2 / g, crystal size d(120) is 15 nm) and 25 g of guar gum powder, mix them evenly to obtain powder A; weigh 1000 g of pseudoboehmite PB-2 (pore volume is 1.2 mL / g, specific surface area is 120 m²) 2 / g, crystal size d(120) is 40 nm) and 25 g of guar gum powder, mix them evenly to obtain powder B; weigh 1000 g of pseudoboehmite PB-2, 25 g of guar gum powder and 80 g of polyethylene powder, mix them evenly to obtain powder C2.
[0041] (2) Add 30 g of citric acid and 35 g of nitric acid to 980 g of water and stir to mix evenly to obtain peptide solvent P2.
[0042] (3) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent P2 to roll into balls. When the average wet ball size reaches 1.6 mm, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and the adhesive solvent P2 is sprayed to continue to form balls. When the average wet ball size reaches 2.8 mm, the feeding of powder B is stopped. Then powder C2 is fed into the sugar coating machine and the adhesive solvent P2 is sprayed to continue to form balls. When the average wet ball size reaches 4.0 mm, the ball forming is completed.
[0043] (4) The wet bulb was cured at room temperature for 24 h, then dried at 80 ℃ for 6 h, and finally calcined at 680 ℃ for 4 h to obtain alumina sample S2.
[0044] Example 3
[0045] (1) Weigh 1000 g of pseudoboehmite PB-1 (pore volume of 1.0 mL / g, specific surface area of 220 m²) 2 / g, crystal size d(120) is 15 nm) and 25 g of guar gum powder, mix them evenly to obtain powder A; weigh 1000 g of pseudoboehmite PB-2 (pore volume is 1.2 mL / g, specific surface area is 120 m²) 2 / g, crystal size d(120) is 40 nm) and 25 g of guar gum powder, mix them evenly to obtain powder B; weigh 1000 g of pseudoboehmite PB-2, 25 g of guar gum powder and 90 g of polyethylene powder, mix them evenly to obtain powder C3.
[0046] (2) Add 30 g of citric acid and 40 g of nitric acid to 980 g of water and stir to mix evenly to obtain peptide solvent P3.
[0047] (3) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent P3 to roll into balls. When the average wet ball size reaches 1.8 mm, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and the adhesive solvent P3 is sprayed to continue to form balls. When the average wet ball size reaches 3.2 mm, the feeding of powder B is stopped. Then powder C3 is fed into the sugar coating machine and the adhesive solvent P3 is sprayed to continue to form balls. When the average wet ball size reaches 4.0 mm, the ball forming is completed.
[0048] (4) The wet bulb was cured at room temperature for 24 h, then dried at 80 ℃ for 6 h, and finally calcined at 680 ℃ for 4 h to obtain alumina sample S3.
[0049] Comparative Example 1
[0050] (1) Weigh 1000 g of pseudoboehmite PB-1 (pore volume of 1.0 mL / g, specific surface area of 220 m²) 2 / g, crystal size d(120) is 15 nm) and 25 g of guar gum powder, are mixed evenly to obtain powder A.
[0051] (2) Add 20 g of citric acid and 35 g of nitric acid to 1000 g of water and stir to mix evenly to obtain peptide solvent P1.
[0052] (3) Powder A is fed into the sugar coating machine and the adhesive solvent P1 is sprayed to roll the balls. When the average particle size of the wet balls reaches 4.0 mm, the ball forming is completed.
[0053] (4) The wet bulb was cured at room temperature for 24 h, then dried at 80 ℃ for 6 h, and finally calcined at 650 ℃ for 4 h to obtain alumina sample CS-1.
[0054] Comparative Example 2
[0055] (1) Weigh 1000 g of pseudoboehmite PB-1 (pore volume of 1.0 mL / g, specific surface area of 220 m²) 2 / g, crystal size d(120) is 15 nm) and 25 g of guar gum powder, mix them evenly to obtain powder A; weigh 1000 g of pseudoboehmite PB-2 (pore volume is 1.2 mL / g, specific surface area is 120 m²) 2 / g, crystal size d(120) is 40 nm) and 25 g of guar gum powder, are mixed evenly to obtain powder B.
[0056] (2) Add 20 g of citric acid and 35 g of nitric acid to 1000 g of water and stir to mix evenly to obtain peptide solvent P1.
[0057] (3) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent P1 to roll into balls. When the average wet ball size reaches 1.5 mm, the feeding of powder A is stopped. Then powder B is fed into the sugar coating machine and the adhesive solvent P1 is sprayed to continue to form balls. When the average wet ball size reaches 4.0 mm, the ball forming ends.
[0058] (4) The wet bulb was cured at room temperature for 24 h, then dried at 80 ℃ for 6 h, and finally calcined at 650 ℃ for 4 h to obtain alumina sample CS-2.
[0059] 1. The physicochemical properties of the alumina obtained in the examples and comparative examples are listed in Table 1.
[0060] The method for determining the average pore diameter of alumina from the center to the outer surface is as follows: During the spherical formation process, when the spherical carrier grows to a certain particle size, the sample is taken out for conditioning, drying and calcination. The pore volume, specific surface area and average pore diameter of the sample are determined by physical adsorption, mercury porosimetry and other analytical methods. The average pore diameter from the center to the outer surface is calculated based on the relationship that the total pore volume and surface area of the sample are equal to the sum of the individual parts.
[0061] Table 1 Physicochemical properties of alumina samples obtained in the examples and comparative examples
[0062]
[0063] As shown in Table 1, the alumina prepared in the examples has an open, stepped-increase pore structure with larger pore volume and pore size. It also has a considerable proportion of pore structures with a diameter greater than 100 nm. The outer pore diameter is significantly larger than the inner pore diameter, and the pores are more open.
[0064] 2. Using the alumina obtained in the examples and comparative examples as a support, active metals were loaded using the same method, so that the corresponding catalysts all contained 5 wt% MoO3 and 1 wt% NiO. The demetallization performance of the obtained catalysts was then evaluated in a 200 mL residue oil hydrotreating pilot unit. The feedstock residue oil had a sulfur content of 4.27 wt%, a nitrogen content of 2870 ppm, a nickel content of 28 ppm, and a vanadium content of 85 ppm. The catalyst loading volume was 100 mL. Before evaluation, the catalyst was pre-sulfurized using a wet pre-sulfurization process. The reaction conditions were: reaction temperature 380℃, hydrogen partial pressure 15 MPa, and liquid hourly space velocity 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 760. The process conditions for evaluating each catalyst were identical.
[0065] The contents of nickel and vanadium in the oil before and after the reaction were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) (see GB / T 37160 for specific methods). The demetallization rate of each catalyst was calculated according to the following formula, and the evaluation results of the catalysts prepared by each alumina support are shown in Table 2.
[0066] .
[0067] Table 2. Results of demetallization rate determination of catalysts prepared using alumina as a support obtained in the examples and comparative examples.
[0068]
[0069] The results in Table 2 show that the catalysts using alumina as a support prepared in the examples have higher demetallization activity and better activity stability.
[0070] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. A method for preparing spherical stepped-pore alumina for use as a catalyst support in upflow residue hydrotreating, characterized in that: Includes the following steps: (1) Mix boehmite PB-1 with molding auxiliary material evenly as powder A, mix boehmite PB-2 with molding auxiliary material evenly as powder B, and mix boehmite PB-2 with molding auxiliary material and template agent evenly as powder C. (2) Powder A is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder A is stopped. Powder B is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the feeding of powder B is stopped. Then powder C is fed into the sugar coating machine and sprayed with adhesive solvent to form balls. When the average wet ball size reaches an appropriate size, the ball forming is completed. (3) The obtained wet bulbs are cured, dried and calcined to obtain the spherical stepped porous alumina; The pseudoboehmite PB-1 mentioned in step (1) has a pore volume of 0.8~1.2 mL / g and a specific surface area of 200~350 m². 2 / g, with a grain size d(120) of 8~20 nm; the pseudoboehmite PB-2 has a pore volume of 1.0~1.5 mL / g and a specific surface area of 80~200 m² / g. 2 / g, crystallite size d(120)≥25 nm; the template agent is one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyurethane, and its addition amount is 5~30% of the dry basis mass of pseudoboehmite PB-2; Based on mercury porosimetry, the pore volume of the obtained alumina is 0.6–1.6 mL / g, and the specific surface area is 80–250 m² / g. 2 / g, the average pore diameter increases in a stepwise manner from the center of the sphere to the outer surface along the radial direction of the sphere. Specifically, the average pore diameter from the center of the sphere to a distance of 30-50% of the sphere radius from the center is 10-25 nm; the average pore diameter from a distance of 30-50% of the sphere radius from the center to a distance of 50-80% of the sphere radius from the center is 20-40 nm; and the average pore diameter from a distance of 50-80% of the sphere radius from the center to the outer surface of the sphere is 40-60 nm. The outer surface of the sphere contains macropores with a diameter of more than 100 nm, and the pore volume corresponding to the macropores accounts for 20%-60% of the total pore volume.
2. The method for preparing spherical stepped-pore alumina according to claim 1, characterized in that: The molding auxiliary material mentioned in step (1) is selected from one or more of guar gum powder, starch, methylcellulose, polyacrylamide, and polycarboxylic acid, and its addition amount is 0.3~5% of the dry basis mass of the corresponding boehmite.
3. The method for preparing spherical stepped porous alumina according to claim 1, characterized in that: The temperature for conditioning in step (3) is 10~40℃ and the time is 6~48 h; the temperature for drying is 50~150℃ and the time is 1~24 h; the temperature for roasting is 600~1000℃ and the time is 1~6 h.