Preparation method of multi-template coupled porous spherical alumina

Abstract

The invention discloses a preparation method of multi-template coupled porous spherical alumina, which comprises the following steps: mixing an aluminum source, water and acid to obtain pseudo sol, adding a soft template agent, a hard template agent and a surfactant into the pseudo sol, uniformly stirring, and then carrying out ultrasonic treatment to obtain composite alumina sol; forming the composite aluminum sol through an oil ammonia column to obtain spherical gel, and then aging, washing, drying and calcining the spherical gel to obtain the spherical aluminum oxide. The spherical alumina prepared by the method has a large number of pores inside, so that the specific surface area and pore volume are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst carriers, and in particular relates to a method for preparing multi-template coupled porous spherical alumina. Background Art

[0002] With the rapid development of industrialization in my country, the consumption of fossil resources is increasing day by day. In 2022, my country's total crude oil imports will reach 508 million tons, and the export volume of refined oil will be 34.4875 million tons. γ-Al2O3 has the advantages of large specific surface area, excellent pore structure, high stability, many surface acid sites, and large adsorption capacity. It is widely used in the petrochemical field as a catalyst and catalyst carrier. Among the various forms of alumina carriers, spherical carriers have the advantages of high rolling properties, uniform stacking, and low wear, and are most widely used in the petrochemical field.

[0003] The main forming methods of spherical alumina include spherical spinning, spray drying, oil-ammonia column, hot oil column and water column. However, it is still a challenge to prepare spherical alumina with high purity, narrow particle size distribution, high hydrothermal stability, high mechanical strength and suitable for industrial production.

[0004] CN116059985A reports a method for synthesizing a spherical alumina carrier, which comprises adding a gelling agent and a curing agent to an aluminum sol, adding the mixed solution to an organic phase, adding an emulsifier to obtain an oil-in-water emulsion, and then molding to obtain spherical alumina.

[0005] CN115920977A provides a method for forming spherical alumina, which uses hydrated alumina as a raw material, acidifies and prepares alumina sol, then drips the sol into a pseudo-homogeneous organic solution formed by fully mixing ammonia and oil, washes, dries and calcines to obtain a spherical alumina carrier.

[0006] CN115872424A discloses a method for preparing spherical alumina, which uses pseudo-boehmite and alumina powder as raw materials, obtains a stable alumina slurry through acidification and addition of a gelling agent, and then obtains spherical alumina through shaping and solidification by an oil-ammonia column method, washing, drying and calcining.

[0007] The above patents focus on controlling the particle size, sphericity and other surface properties of spherical alumina, but neglect the exploration of the internal structure of alumina, and the research on the regulation of pore structure is not in-depth enough.

[0008] Therefore, it is necessary to focus on the regulation of the pore structure of spherical alumina to obtain an alumina carrier with richer pore structure and higher specific surface area. Summary of the invention

[0009] The object of the present invention is to provide a preparation method of multi-template coupled porous spherical alumina. The spherical alumina prepared by this method has a large number of pores inside, and is significantly distributed in both the mesoporous and macroporous ranges.

[0010] To achieve the above object, the present invention provides a preparation method of multi-template coupled porous spherical alumina. An aluminum source, water and an acid are mixed to obtain a pseudo sol. A soft template agent, a hard template agent and a surfactant are added to the pseudo sol. After stirring evenly, the mixture is ultrasonically treated to obtain a composite aluminum sol. The composite aluminum sol is formed into a spherical gel through an oil-ammonia column, and then the spherical gel is aged, washed, dried and calcined to obtain the spherical alumina.

[0011] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the conditions of the ultrasonic treatment are: the voltage of the ultrasonic instrument is set to 12 - 24 V, and the ultrasonic time is 0.5 - 10 min.

[0012] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the soft template agent is a water-insoluble liquid organic matter, preferably a liquid alkane, more preferably one or more of nonane, decane, undecane, dodecane and kerosene. The dosage of the soft template agent is 0.1% - 30% of the mass of the pseudo sol, preferably 5% - 15%.

[0013] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the hard template agent is a carbon-based solid organic matter and / or an inorganic matter, preferably activated carbon and / or starch. The dosage of the hard template agent is 1 - 50% of the mass of the soft template agent, preferably 5 - 10%.

[0014] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the molar ratio of hydrogen ions in the acid to aluminum ions in the aluminum source in the pseudo sol is 0.03 - 0.10.

[0015] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the surfactant is a hydrophilic surfactant, including one or more of anionic surfactants, cationic surfactants and non-ionic surfactants.

[0016] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the dosage of the surfactant is 0.01 - 2% of the mass of the pseudo sol.

[0017] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the calcination conditions are calcination at 550 - 650 °C for 2 - 4 h.

[0018] For the preparation method of multi-template coupled porous spherical alumina of the present invention, the aluminum source is one or more of pseudo-boehmite, boehmite and gibbsite.

[0019] The preparation method of the multi-template coupled porous spherical alumina according to the present invention, the specific surface area of the spherical alumina is 150 - 600 m 2 / g, and the macropore pore size distribution is 50 to 150 nm.

[0020] Advantages of the present invention:

[0021] By introducing a variety of templating agents into the pseudo sol, regulating the relevant dosages and ultrasonic treatment, through the interaction between the templating agents, a composite aluminum sol is obtained, and after forming and curing in an oil-ammonia column, spherical alumina with a variety of pore structure distributions is prepared, significantly increasing the specific surface area and pore volume.

[0022] This preparation method is simple to operate, low in cost, stable in the production process, and easy to produce on a large scale.

[0023] After a large number of pores are prepared inside the alumina in the present invention, the specific surface area is greatly improved, which is beneficial to the loading of the catalyst inside the alumina.

[0024] The present invention uses an ultrasonic instrument to emit ultrasonic waves to drive the hard templating agent to vibrate at a high frequency to break the soft templating agent inside the composite aluminum sol, reducing the size, and then after forming and curing, the pores formed inside the alumina are smaller and the specific surface area is higher.

[0025] The alumina prepared by the present invention has a large specific surface area and a diverse pore structure, with obvious distributions in both the mesopore and macropore ranges, which helps to significantly improve the dispersion and loading of the catalyst in the carrier, improve the performance in petroleum reforming, and has industrial production utilization value and commercial value. Description of the Drawings

[0026] Figure 1 Optical photograph of the multi-template coupled porous spherical alumina prepared in Example 1.

[0027] Figure 2 XRD spectrum of the multi-template coupled porous spherical alumina prepared in Example 1.

[0028] Figure 3 SEM photograph of the multi-template coupled porous spherical alumina prepared in Example 1.

[0029] Figure 4 XRD spectrum of the alumina prepared in Comparative Example 1.

[0030] Figure 5 SEM photograph of the alumina prepared in Comparative Example 1.

[0031] Figure 6 SEM photograph of the alumina prepared in Comparative Example 2. Detailed Embodiments

[0032] The present invention will be specifically described below through embodiments. It is necessary to point out here that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0033] Example 1

[0034] Step 1: Prepare a suspension with a solid content of 15% using 10 g of pseudo-boehmite (pore volume 0.64 mL / g, pore diameter 10.74 nm). Keep the hydrogen-aluminum ratio H + :Al 3+ = 0.05, and add 420 μL of concentrated nitric acid to obtain a pseudo sol.

[0035] Step 2: Add 1.5 g of dodecane and 0.1 g of activated carbon powder as template agents into the pseudo sol obtained in Step 1, and continuously stir. Then add 5 mg of cetyltrimethylammonium bromide (CTAB) as a surfactant, stir for 1 h, and then use a 12 V ultrasonic device to perform ultrasonic dispersion treatment for 0.5 min.

[0036] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether, with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m.

[0037] The spherical particles collected are aged in ammonia water for 12 h, then taken out and washed several times with deionized water. The product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology being spherical particles, an average diameter of 1.7 mm, a bulk density of 0.44 g / mL, a pore volume of 0.76 mL / g, and a specific surface area of 204.3 m 2 / g. There are multiple pore size distributions at 12 nm and 80 nm.

[0038] Example 2

[0039] Step 1: Prepare a suspension with a solid content of 20% using 10 g of pseudo-boehmite (the same as in Example 1). Keep the hydrogen-aluminum ratio H + :Al 3+ = 0.05, and add 420 μL of concentrated nitric acid to obtain a pseudo sol.

[0040] Step 2: Add 2 g of nonane and 0.05 g of starch as template agents into the pseudo sol obtained in Step 1, and continuously stir. Then add 2.5 mg of cetyltrimethylammonium chloride (CTAC) as a surfactant, stir for 1 h, and then use a 12 V ultrasonic device to perform ultrasonic dispersion treatment for 3 min.

[0041] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: The oil phase is petroleum ether with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m; the collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology being spherical particles, an average diameter of 1.9 mm, a bulk density of 0.55 g / mL, a pore volume of 0.65 mL / g, and a specific surface area of 189.5 m 2 / g. There are multiple pore size distributions at 11 nm and 112 nm.

[0042] Example 3

[0043] Step 1: Prepare a suspension with a solid content of 15% using 10 g of pseudo-boehmite (the same as in Example 1), and keep the hydrogen-aluminum ratio H + :Al 3+ = 0.03, add 420 μL of concentrated nitric acid to obtain a pseudo-sol;

[0044] Step 2: Add 2 g of kerosene and 0.1 g of activated carbon powder as template agents to the pseudo-sol described in Step 1, and continuously stir. Then add 0.5 mg of polyvinylpyrrolidone (PVP) as a surfactant, stir for 1 h, and then perform ultrasonic dispersion treatment for 5 min using a 24V ultrasonic device;

[0045] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: The oil phase is petroleum ether with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m; the collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 550 °C for 4 h to obtain the target product γ-aluminum oxide; with the chemical formula γ-Al2O3, its morphology being spherical particles, an average diameter of 1.7 mm, a bulk density of 0.61 g / mL, a pore volume of 0.65 mL / g, and a specific surface area of 193.5 m 2 / g. There are multiple pore size distributions at 10 nm and 82 nm.

[0046] Example 4

[0047] Step 1: Prepare a suspension with a solid content of 15% using 10 g of pseudo-boehmite (the same as in Example 1), and keep the hydrogen-aluminum ratio H + :Al 3+ = 0.03, add 420 μL of concentrated nitric acid to obtain a pseudo-sol;

[0048] Step 2: Add 10 g of dodecane and 0.15 g of activated carbon powder as template agents into the pseudo sol described in Step 1, and continuously stir. Then add 1200 mg of Tween 80 as a surfactant, stir for 1 h, and then perform ultrasonic dispersion treatment for 10 min using a 24V ultrasonic device;

[0049] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m; the collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology is spherical particles, the average diameter is 1.8 mm, the bulk density is 0.61 g / mL, the pore volume is 0.60 mL / g, and the specific surface area is 188.9 m 2 / g. There are multiple pore size distributions at 11 nm and 78 nm.

[0050] Example 5

[0051] Step 1: Prepare a suspension with a solid content of 15% using 10 g of pseudo-boehmite (the same as in Example 1), and keep the hydrogen-aluminum ratio H + :Al 3+ = 0.03, and add 420 μL of concentrated nitric acid to obtain a pseudo sol;

[0052] Step 2: Add 20 g of dodecane and 10 g of activated carbon powder as template agents into the pseudo sol described in Step 1, and continuously stir. Then add 1000 mg of CTAB as a surfactant, stir for 1 h, and then perform ultrasonic dispersion treatment for 10 min using a 24V ultrasonic device;

[0053] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m; the collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology is spherical particles, the average diameter is 1.8 mm, the bulk density is 0.45 g / mL, the pore volume is 0.79 mL / g, and the specific surface area is 385.9 m 2 / g. There are multiple pore size distributions at 13 nm and 89 nm.

[0054] Example 6

[0055] Step 1: Prepare a suspension with a solid content of 15% using 10 g of pseudo-boehmite (the same as in Example 1), and keep the hydrogen-aluminum ratio H +:Al 3+ 0.03 was added and 420 μL of concentrated nitric acid was added to obtain a pseudo sol;

[0056] Step 2: Add 0.07 g of dodecane and 0.02 g of activated carbon powder as template agents to the pseudo sol described in Step 1, and continuously stir. Then add 0.34 mg of CTAB as a surfactant, stir for 1 h, and then use a 24 V ultrasonic device for ultrasonic dispersion treatment for 10 min;

[0057] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether, with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m; the collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology is spherical particles, the average diameter is 1.7 mm, the bulk density is 0.69 g / mL, the pore volume is 0.55 mL / g, and the specific surface area is 201.3 m 2 / g. There are multiple pore size distributions at 11 nm and 76 nm.

[0058] Example 7

[0059] Step 1: 10 g of pseudo-boehmite (the same as in Example 1) was used to prepare a suspension with a solid content of 15%, and the hydrogen-aluminum ratio H + :Al 3+ = 0.1 was added and 840 μL of concentrated nitric acid was added to obtain a pseudo sol;

[0060] Step 2: Add 1.5 g of dodecane and 0.1 g of activated carbon powder as template agents to the pseudo sol described in Step 1, and continuously stir. Then add 5 mg of cetyltrimethylammonium bromide CTAB as a surfactant, stir for 1 h, and then use a 12 V ultrasonic device for ultrasonic dispersion treatment for 0.5 min;

[0061] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether, with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m;

[0062] The collected spherical particles are aged in ammonia water for 12 h, then taken out and washed several times with deionized water, and the product is dried at 80 °C for 10 h; after drying, the product is calcined at 600 °C for 3 h to obtain the target product γ-aluminum oxide, with the chemical formula γ-Al2O3, its morphology is spherical particles, the average diameter is 1.9 mm, the bulk density is 0.50 g / mL, the pore volume is 0.66 mL / g, and the specific surface area is 174.5 m 2 / g. There are multiple pore size distributions at 10 nm and 93 nm.

[0063] Comparative Example 1

[0064] To prepare template-free doped spherical alumina, first, 10 g of pseudo-boehmite (the same as in Example 1) was used to prepare a suspension with a solid content of 15%. While maintaining the hydrogen-aluminum ratio H + :Al 3+ = 0.05, 420 μL of concentrated nitric acid was added to obtain a pseudo-sol; after stirring for 3 h, the obtained pseudo-sol was dropped into an oil-ammonia column: the oil phase was petroleum ether with a height of 8 cm; the ammonia water phase was ammonia water with a mass fraction of 8 wt% and a height of 1 m; the subsequent steps were carried out according to the method of Example 1.

[0065] The characterization test results showed that the prepared alumina had obvious alumina diffraction peaks, no obvious macropores were observed inside, only the pores of pseudo-boehmite itself, and its specific surface area was 174.2 m 2 / g, and the pore size distribution only appeared at 10 nm.

[0066] Comparative Example 2

[0067] To prepare hard-template doped spherical alumina, Step 1: 10 g of pseudo-boehmite (the same as in Example 1) was configured into a suspension with a solid content of 15%. While maintaining the hydrogen-aluminum ratio H + :Al 3+ = 0.05, 420 μL of concentrated nitric acid was added to obtain a pseudo-sol;

[0068] Step 2: 0.1 g of activated carbon powder was added as a template agent to the pseudo-sol described in Step 1, and it was continuously stirred. Subsequently, 15 mg of CTAB was added as a surfactant, and it was stirred for 1 h. Then, ultrasonic dispersion treatment was carried out for 1 min using an ultrasonic device;

[0069] Step 3: The sol obtained in Step 2 was dropped into an oil-ammonia column: the oil phase was petroleum ether with a height of 10 cm; the ammonia water phase was ammonia water with a mass fraction of 8 wt% and a height of 1 m;

[0070] Step 4: The spherical gel obtained in Step 3 was taken out, washed, dried, and calcined to obtain spherical alumina.

[0071] The collected spherical particles were aged in ammonia water for 12 h, then taken out and washed several times with deionized water. The product was placed in an oven at 80 °C and dried for 10 h; after drying, the product was placed in a furnace at 600 °C and calcined for 3 h to obtain the target product γ-alumina; its chemical formula was γ-Al2O3, its morphology was spherical particles, the average diameter was 1.6 mm, the bulk density was 0.68 g / mL, the pore volume was 0.56 mL / g, and the specific surface area was 183.8 m 2 / g. The pore size distribution only appeared at 11 nm.

[0072] Comparative Example 3

[0073] Preparation of soft-template agent-doped spherical alumina, Step 1: Configure 10 g of pseudo-boehmite (same as in Example 1) into a suspension with a solid content of 15%, and keep the hydrogen-aluminum ratio H + :Al 3+ = 0.05, and add 420 μL of concentrated nitric acid to obtain a pseudo-sol;

[0074] Step 2: Add 1.5 g of dodecane as a template agent to the pseudo-sol obtained in Step 1, and continuously stir. Subsequently, add 15 mg of CTAB as a surfactant, stir for 1 h, and then use an ultrasonic device for ultrasonic dispersion treatment for 1 min;

[0075] Step 3: Drop the sol obtained in Step 2 into an oil-ammonia column: the oil phase is petroleum ether, with a height of 10 cm; the ammonia water phase is ammonia water with a mass fraction of 8 wt%, with a height of 1 m;

[0076] Step 4: Take out the spherical gel obtained in Step 3, wash, dry, and calcine it to obtain spherical alumina.

[0077] The collected spherical particles are aged in ammonia water for 12 h, and then taken out and washed several times with deionized water. The product is placed at 80 °C and dried for 10 h; after drying, the product is placed at 600 °C and calcined for 3 h to obtain the target product γ-alumina; its chemical formula is γ-Al2O3, its morphology is spherical particles, the average diameter is 1.6 mm, the bulk density is 0.44 g / mL, the pore volume is 0.72 mL / g, and the specific surface area is 209.6 m 2 / g. There are multiple pore size distributions at 11 nm and 216 nm.

[0078] Certainly, the present invention may also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of multi-template coupled porous spherical alumina, characterized in that, Mix an aluminum source, water, and an acid to obtain a pseudo sol. Add a soft template agent, a hard template agent, and a surfactant to the pseudo sol. After stirring evenly, perform ultrasonic treatment to obtain a composite aluminum sol. Shape the composite aluminum sol through an oil-ammonia column to obtain spherical gels, and then age, wash, dry, and calcine the spherical gels to obtain the spherical alumina.

2. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, wherein The conditions for ultrasonic treatment are as follows: the voltage of the ultrasonic instrument is set to 12 - 24 V, and the ultrasonic time is 0.5 - 10 min.

3. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that The soft template agent is a water-insoluble liquid organic compound, preferably a liquid alkane, more preferably one or more of nonane, decane, undecane, dodecane, and kerosene. The dosage of the soft template agent is 0.1% - 30% of the mass of the pseudo sol, preferably 5% - 15%.

4. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, wherein, The hard template agent is a carbon-based solid organic compound and / or an inorganic compound, preferably activated carbon and / or starch. The dosage of the hard template agent is 1 - 50% of the mass of the soft template agent, preferably 5 - 10%.

5. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, wherein, The molar ratio of hydrogen ions in the acid to aluminum ions in the aluminum source in the pseudo sol is 0.03 - 0.

10.

6. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that, The surfactant is a hydrophilic surfactant, including one or more of anionic surfactants, cationic surfactants, and non-ionic surfactants.

7. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that, The dosage of the surfactant is 0.0005% - 2% of the mass of the pseudo sol.

8. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that, The calcination conditions are calcination at 550 - 650 °C for 2 - 4 h.

9. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that, The aluminum source is one or more of pseudo-boehmite, boehmite, and gibbsite.

10. The preparation method of the multi-template coupled porous spherical alumina according to claim 1, characterized in that, The specific surface area of the spherical alumina is 150 - 600 m 2 / g, and the macropore pore size distribution is 50 to 150 nm.

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