Alumina carrier and its preparation method

Abstract

This invention discloses an alumina support and its preparation method. The alumina support includes an alumina matrix and first sheet-like alumina particles grown in situ on the outer surface of the matrix. The alumina matrix includes granular alumina particles and second sheet-like alumina particles. The size of the first sheet-like alumina particles is 100~600nm, and the sheet-like particles on the surface are stacked to form pores of 40-300nm. The preparation method is as follows: (1) Mix γ-phase alumina powder with propylene oxide aqueous solution and perform hydrothermal treatment to obtain sheet-like boehmite HP1; (2) Mix the sheet-like boehmite HP1 and boehmite P2 from step (1) to form an alumina support precursor; (3) Place the alumina support precursor in propylene oxide solution for a second hydrothermal treatment, and the treated material is used to obtain the alumina support. This alumina support has a rich macroporous content and can be used in macromolecular catalytic reactions, especially suitable for the hydrotreating process of heavy residue oil.

Description

Technical Field

[0001] This invention belongs to the field of materials synthesis, and specifically relates to an alumina carrier and its preparation method. Background Technology

[0002] With the increasing trend of deteriorating crude oil quality and increasingly stringent environmental regulations, residue hydrotreating technology has become a key technology for refineries to improve light oil yield. Among them, the fixed-bed process has developed rapidly due to its advantages such as simple equipment, easy operation, and low investment costs, and is the most widely used and technologically mature residue hydrotreating technology in industry to date.

[0003] Residue oil is the heaviest and most structurally complex fraction of petroleum distillates, enriched with most of the impurities from crude oil, such as sulfur, nitrogen, heterocyclic compounds, soluble metal compounds, gums, and asphaltenes. Therefore, it is also the most difficult fraction to process. Consequently, after prolonged chemical reactions, residual oil fixed-bed hydrotreating catalysts accumulate large amounts of metallic impurities and coke, leading to catalyst deactivation and the formation of...

[0004] The main cause of reaction pressure drop is the presence of metal deposits and coke. These deposits can cover the active sites of the catalyst and block the pores, leading to catalyst deactivation. The pore size of the catalyst is generally determined by the alumina support; therefore, preparing alumina supports with large pores is of great significance.

[0005] CN104646008A discloses a low-quality heavy oil hydrodesulfurization and demetallization catalyst and its preparation method. The catalyst uses alumina as a support and Group VIII and VIB elements, particularly Ni-Mo, as the active components. The catalyst has a pore volume of 0.61-0.70 mL / g and a specific surface area of ​​155-200 m². 2 / g, with an average pore diameter of 13.0-18.0 nm. The preparation method of this catalyst involves treating the shaped and calcined support particles with an acid solution of continuously increasing concentration. Although this method can make the average pore diameter of the final catalyst gradually increase from the center to the outer surface along the radial direction of the catalyst particles to a certain extent, the pores on the support surface are small, which is not conducive to the diffusion of residual oil reactant molecules into the interior of the catalyst, and the surface has poor resistance to metal deposition and carbon buildup.

[0006] CN110935461A discloses a method for preparing a heavy oil hydrodemetallization catalyst. The method includes: (1) mixing a physical pore expander, boehmite, and active metal components, kneading, drying, and calcining to obtain a modified alumina support SI; (2) impregnating SI with an unsaturated impregnation solution I for hydrotreating, followed by drying and calcining to obtain a modified alumina support SII; (3) mixing SII, ammonium bicarbonate, and water, followed by sealed heat treatment, and then drying and calcining the heat-treated material to obtain support SIII; (4) impregnating support SIII with a supersaturated impregnation solution II for hydrotreating, followed by drying and calcining to obtain the catalyst. The alumina support prepared by this method has a rod-shaped surface structure, forming open pores, which improves the catalyst's resistance to metal deposition and carbon buildup. However, the rod-shaped alumina grown on the surface is easy to detach, and the firmness of its bond with the main alumina needs to be further improved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an alumina support and its preparation method. The alumina support is mainly composed of alumina in two forms: granular and flake-like, and has a high macroporous content. This alumina support can be used in macromolecular catalytic reactions and is particularly suitable for the hydrotreating process of heavy residue oil.

[0008] The alumina carrier of the present invention includes an alumina matrix and first sheet-like alumina particles grown in situ on the outer surface of the matrix. The alumina matrix includes granular alumina particles and second sheet-like alumina particles. The size of the first sheet-like alumina particles is 100~600nm, and the sheet-like particles on the surface are stacked to form channels of 40-300nm.

[0009] In the alumina matrix, the size of the granular alumina particles is 20~150nm; the size of the second sheet-like alumina particles is 100~600nm, preferably 100~400nm.

[0010] The first sheet-like alumina particles have a coverage rate of 85%-100% on the outer surface of the alumina substrate, wherein the coverage rate refers to the percentage of the surface occupied by the first sheet-like alumina particles on the outer surface of the alumina substrate.

[0011] In the alumina carrier of the present invention, the contents of the first and second sheet-like alumina particles are 30wt%-60wt%, and the contents of the granular alumina are 40wt%-70wt%.

[0012] The specific surface area of ​​the alumina carrier of the present invention is 185-350 m². 2 / g, with a pore volume of 0.7-1.1mL / g, and pores of 10-30nm accounting for 60%-75% of the total pore volume.

[0013] The method for preparing the alumina support of the present invention includes the following steps:

[0014] (1) Mix γ-phase alumina powder with propylene oxide aqueous solution, and then perform a first hydrothermal treatment. After treatment, the material is filtered, washed and dried to obtain flaky pseudoboehmite HP1.

[0015] (2) The sheet-like pseudoboehmite HP1 and pseudoboehmite P2 from step (1) are mixed and kneaded into a mold, and the molded material is dried and calcined to obtain an alumina carrier precursor.

[0016] (3) The alumina carrier precursor from step (2) is mixed with propylene oxide solution for a second hydrothermal treatment. After treatment, the material is filtered, washed, dried and calcined to obtain the alumina carrier.

[0017] In the method of this invention, the γ-phase alumina powder in step (1) is generally obtained by calcining pseudoboehmite. The pseudoboehmite particles are generally granular and can be commercially available products or prepared by methods such as acid precipitation, alkali precipitation, or aluminum alkoxide hydrolysis. The calcination temperature is 450-550℃, and the calcination time is 4-8 hours.

[0018] In the method of the present invention, the concentration of the propylene oxide aqueous solution in step (1) is 2.5wt%-12wt%, preferably 4wt%-8wt%, and the mass ratio of the amount of propylene oxide aqueous solution to the mass ratio of γ-phase alumina powder is 3:1-10:1, preferably 4:1-8:1.

[0019] In the method of the present invention, the first hydrothermal treatment in step (1) is generally carried out in a closed container, preferably a high-pressure autoclave, the closed heat treatment temperature is 110-180℃, preferably 120-160℃, the closed heat treatment time is 4-8 hours, and the pressure inside the sealed container during the closed heat treatment is the self-generated pressure.

[0020] In the method of the present invention, the drying temperature in step (1) is 100-160℃ and the drying time is 2-8 hours.

[0021] In the method of the present invention, the pseudoboehmite P2 mentioned in step (2) can be prepared by existing methods. The particle morphology is generally granular, such as acid precipitation, alkali precipitation, aluminum alkoxide hydrolysis, etc., and preferably pseudoboehmite with a pore size of 10-20 nm.

[0022] In the method of the present invention, the mass ratio of pseudoboehmite HP1 to pseudoboehmite P2 in step (2) is 3:7-3:2.

[0023] In the method of this invention, the kneading and molding in step (2) is carried out using conventional methods in the art. During the molding process, conventional molding aids, such as adhesives, extrusion aids, etc., can be added as needed. The adhesive is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid, etc., and the mass percentage concentration of the adhesive is 0.5%-2%. The amount of adhesive used depends on the molding effect. The extrusion aid is guar gum powder, and the amount added is 1%-3% of the final alumina carrier weight.

[0024] In the method of the present invention, the drying temperature in step (2) is 100-160℃, the drying time is 6-10 hours, the calcination temperature is 450-750℃, preferably 500-600℃, and the calcination time is 4-6 hours.

[0025] In the method of the present invention, the concentration of the propylene oxide aqueous solution in step (3) is 2.5wt%-12wt%, preferably 4wt%-8wt%, and the mass ratio of the amount of propylene oxide aqueous solution to the mass ratio of the alumina carrier precursor is 3:1-10:1, preferably 4:1-8:1.

[0026] In the method of the present invention, the second hydrothermal treatment in step (3) is generally carried out in a closed container, preferably a high-pressure autoclave, the closed heat treatment temperature is 110-180℃, preferably 120-160℃, the closed heat treatment time is 14-20 hours, and the pressure inside the sealed container during the closed heat treatment is the self-generated pressure.

[0027] In the method of the present invention, the drying temperature in step (3) is 100-160℃, the drying time is 6-10 hours, the calcination temperature is 450-750℃, preferably 500-600℃, and the calcination time is 4-6 hours.

[0028] The alumina support of the present invention has abundant and interconnected macropores, which can be used in the reaction of macromolecular multiphase catalysts, and is particularly suitable for the hydrotreating process of heavy residue oil.

[0029] The present invention also provides a hydrogenation catalyst comprising the aforementioned alumina support.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) In this invention, γ-phase alumina powder is heat-treated in propylene oxide solution. During the heat treatment, the γ-phase alumina powder undergoes a rehydration reaction and forms platy boehmite. The platy particles accumulate to form a large number of macropores. During extrusion molding, both platy and granular forms of boehmite are selected. Because the platy particles support each other, the macropores formed are preserved relatively completely, ensuring the macropore content of the final carrier.

[0032] (2) When the alumina carrier precursor is subjected to secondary heat treatment in propylene oxide solution, the particles on the carrier surface are rehydrated twice, and the resulting sheet-like particles grow in situ on the carrier surface and form open channels of 40-300 nm. The sheet-like particles have a strong interaction with the carrier and are not easy to fall off. The open channels on the surface are conducive to the diffusion of macromolecular reactants into the interior of the carrier, thereby improving the utilization rate of the internal channels of the carrier. Attached Figure Description

[0033] Figure 1 is a SEM image of the platy boehmite prepared in Example 1.

[0034] Figure 2 is a SEM image of the outer surface of the alumina carrier prepared in Example 1. Detailed Implementation

[0035] The technical solution and effects of the present invention will be further illustrated below with reference to the embodiments, but the invention is not limited to the following embodiments. In the present invention, wt% represents mass fraction.

[0036] BET Method: The pore structure of the carriers in the examples and comparative examples was characterized using N2 physical adsorption-desorption. The specific procedure was as follows: The pore structure of the samples was characterized using an ASAP-2420 N2 physical adsorption-desorption instrument. A small amount of sample was vacuum-treated at 300℃ for 3-4 hours, and finally, the product was placed under liquid nitrogen cryogenic conditions (-200℃) for nitrogen adsorption-desorption testing. The specific surface area was obtained according to the BET equation, and the pore volume and pore diameter distribution below 30nm were obtained according to the BJH model.

[0037] The microstructure of the alumina support was characterized using scanning electron microscopy. The specific operation was as follows: The microstructure of the support was characterized using a JSM-7500F scanning electron microscope with an accelerating voltage of 5KV, an accelerating current of 20µA, and a working distance of 8mm. Example 1

[0038] (1) γ-phase alumina powder was obtained by calcining boehmite powder at 450℃ for 5 hours. 100 g of γ-phase alumina powder was weighed and 530 g of 6.5 wt% propylene oxide aqueous solution was added. The mixture was magnetically stirred for 30 minutes. The mixture was then transferred to an autoclave, sealed, and heated at 145℃ for 5.5 hours. After cooling, the solid material was filtered, washed, and dried at 120℃ for 6 hours to obtain flaky boehmite. The scanning electron microscope image is shown below. Figure 1 .

[0039] (2) Weigh 133g of the flaky boehmite from step (1), 200g of the boehmite P2, and 0.5g of guar gum powder. Mix the above materials evenly, add an appropriate amount of acetic acid aqueous solution with a mass concentration of 1%, knead, extrude into strips, dry the formed material at 120℃ for 8 hours, and calcine the dried material in air at 550℃ for 5 hours to obtain the alumina carrier precursor.

[0040] (3) Weigh 100 g of the alumina carrier precursor from step (2), add 550 g of a 6.3 wt% propylene oxide aqueous solution, stir magnetically for 30 minutes, then transfer the mixture into an autoclave, seal it, and heat it at 150°C for 17 hours. After cooling, filter and wash the solid material, dry it at 120°C for 8 hours, and calcine it at 600°C for 5 hours to obtain alumina carrier S-1. The scanning electron microscope image of the outer surface of the carrier is shown in the figure. Figure 2 The properties of the carrier are shown in Table 1. Example 2

[0041] Same as Example 1, except that in step (1), the concentration of the propylene oxide solution is 5.5 wt%, the amount of solution used is 610 g, the hydrothermal treatment temperature is 135 °C, and the treatment time is 6.5 hours. In step (2), the amount of flaky boehmite added is 164 g. In step (3), the concentration of the propylene oxide solution is 5.2 wt%, the amount of solution used is 650 g, the hydrothermal treatment temperature is 140 °C, and the treatment time is 18 hours, thus obtaining the alumina carrier S-2 of the present invention. The properties of the carrier are shown in Table 1. Example 3

[0042] Same as Example 1, except that in step (1), the concentration of the propylene oxide solution is 4.5 wt%, the amount of solution used is 750 g, the hydrothermal treatment temperature is 125 °C, and the treatment time is 7.5 hours. In step (2), the amount of flaky boehmite added is 107 g. In step (3), the concentration of the propylene oxide solution is 7.4 wt%, the amount of solution used is 450 g, the hydrothermal treatment temperature is 130 °C, and the treatment time is 19 hours, thus obtaining the alumina carrier S-3 of the present invention. The properties of the carrier are shown in Table 1. Example 4

[0043] Same as Example 1, except that in step (1), the concentration of the propylene oxide solution is 7.5 wt%, the amount of solution used is 420 g, the hydrothermal treatment temperature is 155 °C, and the treatment time is 4.5 hours. In step (2), the amount of flaky boehmite added is 245 g. In step (3), the concentration of the propylene oxide solution is 4.3 wt%, the amount of solution used is 750 g, the hydrothermal treatment temperature is 160 °C, and the treatment time is 16 hours, thus obtaining the alumina carrier S-4 of the present invention. The properties of the carrier are shown in Table 1.

[0044] Comparative Example 1

[0045] Same as Example 1, except that the hydrothermal treatment time in step (1) was 1.5 hours, and no flaky particles were observed to be generated in the powder after hydrothermal treatment. The hydrothermal treatment time in step (3) was 2.5 hours, and no flaky particles were observed to be generated on the surface of the carrier after hydrothermal treatment. The comparative alumina carrier S-5 was obtained, and the properties of the carrier are shown in Table 1.

[0046] Comparative Example 2

[0047] Same as Example 1, except that the propylene oxide aqueous solution in steps (1) and (3) is replaced with ethylene oxide aqueous solution of the same concentration. No flaky particles were observed to be generated in the powder after hydrothermal treatment in step (1), and no flaky particles were observed to be generated on the surface of the carrier after hydrothermal treatment in step (3). The comparative alumina carrier S-6 was obtained, and the properties of the carrier are shown in Table 1.

[0048] Comparative Example 3

[0049] Same as Example 1, except that the concentration of propylene oxide aqueous solution in steps (1) and (3) is 1.0 wt%, no flaky particles are observed to be generated in the powder after hydrothermal treatment in step (1), and no flaky particles are observed to be generated on the surface of the carrier after hydrothermal treatment in step (3). Comparative alumina carrier S-7 is obtained, and the properties of the carrier are shown in Table 1.

[0050] Comparative Example 4

[0051] Same as Example 1, except that the hydrothermal treatment temperature in steps (1) and (3) is 55°C. No flaky particles were observed to be generated in the powder after hydrothermal treatment in step (1), and no flaky particles were observed to be generated on the surface of the carrier after hydrothermal treatment in step (3). Comparative alumina carrier S-8 was obtained, and the properties of the carrier are shown in Table 1.

[0052] Table 1 Properties of Alumina Supports

[0053] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 carrier S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 <![CDATA[Specific surface area, m 2 / g]]> 187 195 175 201 183 175 186 181 Pore ​​volume, mL / g 0.91 0.89 0.94 0.92 0.88 0.83 0.87 0.88 10-30nm pore content, % 63.4 66.7 60.5 68.9 51.3 42.5 43.7 43.1 Alumina content in flakes, % 42.1 45.4 36.8 56.7 — — — — The size of the first sheet-like alumina particle is in nm. 110-520 120-535 125-550 115-560 — — — — First layer of alumina particle coverage, % 95 93 91 94 — — — — The size of the second sheet-like alumina particles is in nm. 100-360 110-380 120-385 105-390 — — — —

[0054] From the data in Table 1 and Figure 1-2 As can be seen, compared with the comparative example, the alumina carrier prepared by the method of the present invention has larger surface pores, better openness, and a higher content of 10-30nm pores. Example 5

[0055] 50 g of the alumina support from the above examples and comparisons was weighed and placed in a spray impregnation boiling pot. The alumina support was impregnated by a saturated impregnation solution containing molybdenum oxide at a concentration of 8.5 g / 100 mL and nickel oxide at a concentration of 2.2 g / 100 mL. The impregnated material was dried at 120 °C for 4 hours and calcined at 500 °C for 5 hours to obtain hydrogenation demetallization catalysts Cat-1 to Cat-8. These catalysts were then loaded into fixed-bed hydrogenation reactors. The feedstocks were processed (see Table 2). The experimental conditions were as follows: reaction temperature 380 °C, hydrogen-to-oil volume ratio 850, and liquid hourly space velocity 0.65 h⁻¹. -1 The hydrogen partial pressure was 14.0 MPa, and the impurity removal properties were obtained after 2000 hours of continuous operation. See Table 3 for the properties of the impurity removal.

[0056] Table 2 Properties of Crude Oil

[0057]

[0058] Table 3 Evaluation results of the catalyst

[0059] catalyst Cat-1 Cat-2 Cat-3 Cat-4 Cat-5 Cat-6 Cat-7 Cat-8 Relative Ni+V removal rate, % 141 135 146 138 100 94 97 98

[0060] As can be seen from the results in Table 3, the hydrodemetallization catalyst prepared using alumina as a support by the method of the present invention has high demetallization Ni and V activity as well as high activity stability.

Claims

1. An alumina support, characterized by: The alumina carrier comprises an alumina matrix and first flaky alumina particles grown in situ on the outer surface of the matrix, the alumina matrix comprises granular alumina particles and second flaky alumina particles, the size of the first flaky alumina particles is 100-600 nm, the surface flaky particles are accumulated to form 40-300 nm channels, the size of the granular alumina particles is 20-150 nm, and the size of the second flaky alumina particles is 100-600 nm; the coverage of the first flaky alumina particles on the outer surface of the alumina matrix is 85%-100%, wherein the coverage refers to the percentage of the surface occupied by the first flaky alumina particles in the outer surface of the alumina matrix; the specific surface area of the alumina carrier is 185-350 m 2 / g, the pore volume is 0.7-1.1 mL / g, and the pore volume of 10-30 nm pores accounts for 60%-75% of the total pore volume; and the preparation method of the alumina carrier comprises the following steps: (1) mixing γ-phase alumina powder and propylene oxide aqueous solution, then performing first hydrothermal treatment, and then filtering, washing and drying the treated material to obtain flaky pseudo-boehmite HP1; (2) mixing and kneading the flaky pseudo-boehmite HP1 of step (1) with pseudo-boehmite P2, drying and calcining the formed material to obtain an alumina carrier precursor; (3) mixing the alumina carrier precursor of step (2) with propylene oxide aqueous solution to perform second hydrothermal treatment, and then filtering, washing, drying and calcining the treated material to obtain the alumina carrier; the concentration of the propylene oxide aqueous solution in steps (1) and (3) is 2.5wt%-12wt%, and the mass ratio of the propylene oxide aqueous solution to the γ-phase alumina powder is 3:1-10:1; the first hydrothermal treatment of step (1) and the second hydrothermal treatment of step (3) are performed in a sealed container, the sealed heat treatment temperature is 110-180℃, the sealed heat treatment time is 4-8 hours, and the pressure in the sealed container during the sealed heat treatment is autogenous pressure.

2. The alumina support of claim 1, wherein: The second flaky alumina particle size is 100-400 nm.

3. The alumina support of claim 1, wherein: The first and second flaky alumina particle content is 30wt%-60wt%, and the particulate alumina particle content is 40wt%-70wt%.

4. A process for the production of the alumina carrier as claimed in any one of claims 1 to 3, characterized in that The following is included: (1) mixing γ phase alumina powder with propylene oxide aqueous solution, then performing first hydrothermal treatment, filtering, washing and drying the treated material to obtain flaky pseudo-boehmite HP1; (2) mixing the flaky pseudo-boehmite HP1 of step (1) with pseudo-boehmite P2, drying and calcining the formed material to obtain an alumina carrier precursor; (3) mixing the alumina carrier precursor of step (2) with propylene oxide aqueous solution to perform second hydrothermal treatment, filtering, washing, drying and calcining the treated material to obtain an alumina carrier.

5. The method of claim 4, wherein: The propylene oxide aqueous solution concentration of step (1) is 4wt%-8wt%, and the mass ratio of propylene oxide aqueous solution to γ phase alumina powder is 4:1-8:

1.

6. The method of claim 4, wherein: The first hydrothermal treatment of step (1) is a closed heat treatment at a temperature of 120-160℃.

7. The method of claim 4, wherein: The pseudo-boehmite P2 of step (2) is in a particulate form, and the pore size of the pseudo-boehmite P2 is 10-20 nm.

8. The method of claim 4, wherein: The mass ratio of the pseudo-boehmite HP1 to the pseudo-boehmite P2 of step (2) is 3:7-3:

2.

9. The method of claim 4, wherein: The propylene oxide aqueous solution concentration of step (3) is 4wt%-8wt%, and the mass ratio of propylene oxide aqueous solution to alumina carrier precursor is 4:1-8:

1.

10. The method of claim 4, wherein: The second hydrothermal treatment of step (3) is a closed heat treatment at a temperature of 120-160℃.

11. The method of claim 4, wherein: The drying temperature of step (3) is 100-160℃, the drying time is 6-10 hours, the calcination temperature is 450-750℃, and the calcination time is 4-6 hours.

12. Use of the alumina carrier of any one of claims 1-3 in a macromolecular heterogeneous catalyst reaction.

13. A hydrogenation catalyst characterized by The catalyst includes the alumina carrier of any one of claims 1-3.

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