Continuous synthesis device and method for pseudo-boehmite

Abstract

The invention discloses a continuous synthesis device and method for pseudo-boehmite, and belongs to the field of chemical material synthesis. The device comprises a raw material storage tank, a rotary liquid membrane reactor, a stirring tank, a tubular reactor, a vibration motor and a heating device. Three raw materials stored in different raw material storage tanks are conveyed into a liquid membrane reactor through a pump in a parallel flow mode, slurry generated after reaction flows into a stirring tank by means of gravity and then is conveyed into a tubular reactor which is placed in a heating device and preheated to a set temperature through a pump, and the tubular reactor and a vibration motor are fixed to the same vibration platform. The vibration motor is arranged outside the heating device, and vibration waves generated during operation of the vibration motor are conducted to the tubular reactor through the vibration platform. The slurry is aged in the tubular reactor and enters a product collecting tank after flowing out. The obtained pseudo-boehmite is uniform in particle size distribution, the particle size fluctuation range is small in the continuous synthesis period, energy consumption is reduced through continuous preparation, and efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a continuous synthesis device and method for pseudo-boehmite, belonging to the field of chemical material synthesis. Background Art

[0002] Pseudo-boehmite, with the chemical formula AlOOH·nH2O (n = 0.08 - 0.62), is a hydrate of alumina with relatively low crystallinity. Pseudo-boehmite has a wide range of applications. For example, the acidified pseudo-boehmite slurry obtained by adding acid to pseudo-boehmite and peptizing it can be used as a binder for preparing fluid catalytic cracking (FCC) catalysts; pseudo-boehmite can be calcined at different temperatures to prepare alumina with different crystal forms such as γ-Al2O3, δ-Al2O3, θ-Al2O3, and α-Al2O3.

[0003] The main production methods of pseudo-boehmite include: (1) the inorganic aluminum salt precipitation method, such as co-precipitation of aluminum sulfate and sodium meta-aluminate or neutralization of sodium meta-aluminate with CO2 gas, followed by aging, washing, and drying to obtain pseudo-boehmite products; (2) the alkoxyaluminum hydrolysis method, such as hydrolysis of aluminum isopropoxide, followed by aging, washing, and drying to obtain pseudo-boehmite products. Currently, most industrial production of pseudo-boehmite uses batch processes, and the equipment used is mostly autoclave reactors. Due to the relatively long duration of the precipitation reaction, the particles formed first stay in the autoclave for a long time, and through growth, aggregation, etc., the final particle size is relatively large; while the particles formed later have a short residence time and a relatively small final particle size. This ultimately results in product quality problems such as uneven product particle size distribution and large fluctuations in product performance between batches. At the same time, it also has the common disadvantages of batch processes, such as low efficiency, high energy consumption, and high labor intensity. For this reason, continuous production processes for pseudo-boehmite have been developed.

[0004] For example, the device used in Patent CN112694112A includes: a series of a first reaction kettle, a second reaction kettle, and an aging device; continuously adding an aluminum sulfate solution to the first reaction kettle, and simultaneously adding a carbonate solution in a co-current manner to obtain a mixed material; when the mixed material reaches or is higher than the overflow port of the first reaction kettle, it enters the second reaction kettle, and at the same time, adding an aluminum-containing alkaline solution to the second reaction kettle in a co-current manner for a neutralization reaction to obtain a slurry, controlling the residence time of the slurry in the second reaction kettle; when the slurry reaches or is higher than the overflow port of the second reaction kettle, it enters the aging device to start aging, and then through filtration, the obtained filter cake is washed and dried to obtain pseudo-boehmite. Although this method can achieve continuous operation, it still cannot solve the problem of uneven product particle size distribution.

[0005] The device used in Patent CN111377466A includes: a kettle reactor, a hydrocyclone separator, an aging device, and a mixing device, with two reactors, two hydrocyclone separators, and two aging devices respectively; through the preparation and separation of aluminum hydroxide in the primary and secondary reactors, combined with adjusting the pH value with an alkaline solution and the aging reaction of a flocculant, multiple separations and aging of the slurry are achieved, and finally washing and drying are carried out in the mixing device to obtain the pseudo-boehmite product. This method has a relatively complex process, and the particle size distribution of the product is still relatively wide. Summary of the Invention

[0006] To solve the above problems, the present invention provides a continuous synthesis device and method for pseudo-boehmite.

[0007] A device for continuously preparing pseudo-boehmite includes a raw material storage tank, a rotating liquid film reactor, a stirring tank, a tubular reactor, a vibration motor, a heating device, pipelines and valves connecting them to each other, and a pump for providing power, etc. Three raw materials stored in different raw material storage tanks are transported in parallel by the pump to the liquid film reactor, and the slurry generated after the reaction flows into the stirring tank by gravity, and then is transported by the pump into the tubular reactor placed in the heating device and preheated to a set temperature. The tubular reactor and the vibration motor are fixed on the same vibration platform, and the vibration motor is placed outside the heating device, and the vibration wave generated during its operation is transmitted to the tubular reactor through the vibration platform. The slurry completes the aging process in the tubular reactor and flows out and enters the product collection tank.

[0008] The rotating liquid film reactor includes a kettle body, a stator, a rotor, a feed inlet, a discharge outlet, and a motor, etc.

[0009] The rotating liquid film reactor has a total of three feed inlets, which are respectively connected to three raw material storage tanks; preferably, the three feed inlets are at the same horizontal plane and have the same spacing.

[0010] The stirring tank is a double-layer structure with a jacket, and the temperature of the slurry can be controlled by introducing water, oil, etc. into the jacket.

[0011] The shape of the tubular reactor can be spiral, four-leaf clover, U-shaped, etc.; the inner diameter of the tubular reactor is 4.0 - 15.0 mm.

[0012] The heating device is an oven, a water bath, an oil bath, a sand bath, etc. The heating temperature is 30 - 70 °C.

[0013] The vibration motor is preferably a two-stage vibration motor.

[0014] The tubular reactor and the vibration motor are placed on the same platform, the tubular reactor is located inside the heating device, and the vibration motor is located outside the heating device;

[0015] A method for using an apparatus for continuously preparing pseudo-boehmite, comprising the following steps:

[0016] Three solutions of raw material 1, raw material 2, and raw material 3 flow through different feed ports and enter a rotating liquid film reactor. Under the high shear force provided by a rotor rotating at high speed therein, the three raw materials are rapidly mixed to achieve uniform nucleation. After the slurry flows out of the discharge port of the rotating liquid film reactor, it flows into a stirring tank by virtue of the head difference, and then is pumped to a tubular reactor connected to a vibration motor. After passing through the tubular reactor, a pseudo-boehmite slurry with a uniform particle size distribution is obtained.

[0017] The above-mentioned raw material 1 is an aqueous solution of aluminum sulfate, aluminum nitrate, aluminum chloride, or a mixture thereof, wherein the mass fraction of aluminum is 1.0% - 2.5%. Raw material 2 is an aqueous solution of sodium aluminate, wherein the mass fraction of aluminum is 2.0% - 6.0%. Raw material 3 is an aqueous solution of a surfactant, wherein the mass fraction of the surfactant is 0.1% - 1.0%.

[0018] By adjusting the flow rates of raw material 1 and raw material 2, the pH value of the slurry flowing out of the discharge port of the rotating liquid film reactor is 8.0 - 10.0, and the flow rate of raw material 3 is equivalent to 5% - 50% of the sum of the flow rates of raw material 1 and raw material 2;

[0019] The residence time of the slurry in the stirring tank is 10.0 - 30.0 min;

[0020] The flow rate of the slurry entering the tubular reactor is equal to the sum of the flow rates of the three raw materials, and the residence time of the slurry therein is 1.0 - 5.0 hr.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The obtained pseudo-boehmite has a uniform particle size distribution, a small fluctuation amplitude of the particle size during continuous synthesis, and continuous preparation reduces energy consumption and improves efficiency. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. The following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings, wherein:

[0024] Figure 1Schematic flow chart of the present invention. 1 - Storage tank for raw material 1; 2 - Storage tank for raw material 2; 3 - Storage tank for raw material 3; 4 - Pump for raw material 1; 5 - Pump for raw material 2; 6 - Pump for raw material 3; 7 - Rotating liquid film reactor; 8 - Stirring tank; 9 - Slurry pump; 10 - Tubular reactor; 11 - Shock-absorbing spring; 12 - Heating device; 13 - Vibration conduction plate; 14 - Vibration motor; 15 - Product tank.

[0025] Figure 2 Particle size distribution diagram of solid particles in the pseudo-boehmite slurry prepared in the example and comparative example of the present invention. Detailed implementation manners

[0026] Example 1

[0027] Weigh 300.0 g of solid Al2(SO4)3·18H2O and completely dissolve it in 900 mL of deionized water to obtain raw material 1. Weigh 320.0 g of solid NaAlO2 and completely dissolve it in 900 mL of deionized water to obtain raw material 2. Weigh 2.5 g of polyvinylpyrrolidone (K = 30) solid and completely dissolve it in 500 mL of deionized water to obtain raw material 3. The tubular reactor used is spiral, placed in an oven. The inner diameter of the reactor is 9 mm, the spiral curvature radius is 125 mm, the number of spiral turns is 20, and the liquid holdup is about 1.0 L. Turn on the water bath connected to the jacket of the stirring tank and set the temperature to 60°C. Turn on the oven where the spiral coil is placed and set the temperature to 60°C. After the water bath and the oven are heated to the set value for 30 min, turn on the liquid film reactor and set the rotation speed to 3000 r / min. At the same time, turn on the pumps for raw material 1, raw material 2, and raw material 3, with flow rates of 300 mL / h, 300 mL / h, and 100 mL / h respectively. At this time, the pH value of the slurry at the outlet of the liquid film reactor is 9.0. The obtained slurry flows out from the outlet of the liquid film reactor and enters the stirring tank, and the stirring speed is controlled at 300 r / min. After 15 min, turn on the slurry pump, set the slurry flow rate to 700 mL / h, turn on the vibration motor, and set the vibration frequency to 10 Hz. The residence time of the slurry in the tubular reactor is 1.4 h, and a laser particle size analyzer is used to measure the particle size of the solid particles in the outflowing slurry.

[0028] Example 2

[0029] Weigh 100.0 g of solid Al(NO3)3·9H2O and completely dissolve it in 620 mL of deionized water to obtain Feedstock 1. Weigh 100.0 g of solid NaAlO2 and completely dissolve it in 660 mL of deionized water to obtain Feedstock 2. Weigh 0.5 g of polyethylene glycol solid and completely dissolve it in 250 mL of deionized water to obtain Feedstock 3. The tubular reactor used is four-leaf clover-shaped and placed in an oven. The inner diameter of the reactor is 4 mm, the curvature radius of a single four-leaf clover petal is 60 mm, there are 25 four-leaf clovers in total, and the holdup is about 0.5 L. Turn on the water bath connected to the jacket of the stirred tank and set the temperature to 50 °C. Turn on the oven with a spiral coil and set the temperature to 50 °C. After the water bath and the oven have heated up to the set value for 30 min, turn on the liquid membrane reactor and set the rotation speed to 4000 r / min. At the same time, turn on the pumps for Feedstock 1, Feedstock 2, and Feedstock 3, with flow rates of 200 mL / h, 200 mL / h, and 100 mL / h respectively. At this time, the pH value of the slurry at the outlet of the liquid membrane reactor is 9.3. The obtained slurry flows out from the outlet of the liquid membrane reactor and enters the stirred tank, and the stirring speed is controlled at 400 r / min. After 15 min, turn on the slurry pump and set the slurry flow rate to 500 mL / h. Turn on the vibration motor and set the vibration frequency to 8 Hz. The residence time of the slurry in the tubular reactor is 1.0 h, and a laser particle size analyzer is used to measure the particle size of the solid particles in the outflowing slurry.

[0030] Comparative Example 1

[0031] Weigh 300.0 g of solid Al2(SO4)3·18H2O and completely dissolve it in 900 mL of deionized water to obtain Feedstock 1. Weigh 320.0 g of solid NaAlO2 and completely dissolve it in 900 mL of deionized water to obtain Feedstock 2. Weigh 2.5 g of polyvinylpyrrolidone (K = 30) solid and completely dissolve it in 500 mL of deionized water to obtain Feedstock 3. The tubular reactor used is spiral-shaped and placed in an oven. The inner diameter of the reactor is 9 mm, the spiral curvature radius is 125 mm, the number of spiral turns is 20, and the holdup is about 1.0 L. Turn on the water bath connected to the jacket of the stirred tank and set the temperature to 60 °C. Turn on the oven with a spiral coil and set the temperature to 60 °C. After the water bath and the oven have heated up to the set value for 30 min, turn on the liquid membrane reactor and set the rotation speed to 3000 r / min. At the same time, turn on the pumps for Feedstock 1, Feedstock 2, and Feedstock 3, with flow rates of 300 mL / h, 300 mL / h, and 100 mL / h respectively. At this time, the pH value of the slurry at the outlet of the liquid membrane reactor is 9.0. The obtained slurry flows out from the outlet of the liquid membrane reactor and enters the stirred tank, and the stirring speed is controlled at 300 r / min. After 15 min, turn on the slurry pump and set the slurry flow rate to 700 mL / h. The residence time of the slurry in the tubular reactor is 1.4 h, and a laser particle size analyzer is used to measure the particle size of the solid particles in the outflowing slurry.

[0032] Comparative Example 2

[0033] Weigh 100.0 g of solid Al(NO3)3·9H2O and completely dissolve it in 620 mL of deionized water to obtain Raw Material 1. Weigh 100.0 g of solid NaAlO2 and completely dissolve it in 660 mL of deionized water to obtain Raw Material 2. The tubular reactor used is four-leaf clover-shaped and placed in an oven. The inner diameter of the reactor is 4 mm, the curvature radius of a single four-leaf clover petal is 60 mm, there are 25 four-leaf clovers in total, and the holdup is about 0.5 L. Turn on the water bath connected to the jacket of the stirring tank and set the temperature to 50 °C. Turn on the oven with the spiral coil and set the temperature to 50 °C. After the water bath and the oven are heated to the set value for 30 min, turn on the liquid film reactor and set the rotation speed to 4000 r / min. At the same time, turn on the pumps for Raw Material 1 and Raw Material 2, with flow rates of 250 mL / h and 250 mL / h respectively. At this time, the pH value of the slurry at the outlet of the liquid film reactor is 9.3. The obtained slurry flows out from the outlet of the liquid film reactor and enters the stirring tank, and the stirring speed is controlled at 400 r / min. After 15 min, turn on the slurry pump, set the slurry flow rate to 500 mL / h, turn on the vibration motor, and set the vibration frequency to 8 Hz. The residence time of the slurry in the tubular reactor is 1.0 h, and a laser particle size analyzer is used to measure the particle size of the solid particles in the outflowing slurry.

[0034] Comparative Example 3

[0035] Weigh 300.0 g of solid Al2(SO4)3·18H2O and completely dissolve it in 900 mL of deionized water to obtain Raw Material 1. Weigh 320.0 g of solid NaAlO2 and completely dissolve it in 900 mL of deionized water to obtain Raw Material 2. Weigh 2.5 g of polyvinylpyrrolidone (K = 30) solid and completely dissolve it in 500 mL of deionized water to obtain Raw Material 3. Turn on the water bath connected to the jacket of the stirring tank and set the temperature to 60 °C. After the water bath is heated to the set value for 30 min, turn on the liquid film reactor and set the rotation speed to 3000 r / min. At the same time, turn on the pumps for Raw Material 1, Raw Material 2, and Raw Material 3, with flow rates of 300 mL / h, 300 mL / h, and 100 mL / h respectively. At this time, the pH value of the slurry at the outlet of the liquid film reactor is 9.0. The obtained slurry flows out from the outlet of the liquid film reactor and enters the stirring tank, and the stirring speed is controlled at 300 r / min. After 15 min, turn off the three raw material pumps and the liquid film reactor, and the slurry continues to be stirred in the stirring tank for 1.4 h. A laser particle size analyzer is used to measure the particle size of the solid particles in the slurry.

Claims

1. An apparatus for continuously preparing pseudo-boehmite, characterized in that, It includes raw material storage tanks, a rotating liquid film reactor, a stirring tank, a tubular reactor, a vibrating motor, a heating device, and pipelines and valves connecting them; three raw materials stored in different raw material storage tanks are transported in parallel by pumps to the liquid film reactor, and the slurry generated after the reaction flows into the stirring tank by gravity, and then is transported by a pump to the tubular reactor placed in the heating device and preheated to the set temperature. The tubular reactor and the vibrating motor are fixed on the same vibrating platform. The vibrating motor is placed outside the heating device, and the vibration waves generated during its operation are conducted to the tubular reactor through the vibrating platform; the slurry completes the aging process in the tubular reactor and flows out and into the product collection tank; The rotating liquid film reactor includes a reactor body, a stator, a rotor, a feed inlet, a discharge outlet, and a motor; There are three feed inlets for the rotating liquid film reactor, which are respectively connected to three raw material storage tanks. The three feed inlets are at the same horizontal plane and have the same spacing.

2. The device for continuously preparing pseudo-boehmite according to claim 1, wherein The stirring tank is a double-layer structure with a jacket, and the slurry temperature can be controlled by passing water or oil into the jacket.

3. The apparatus for continuously preparing pseudo-boehmite according to claim 1, characterized in that, The shape of the tubular reactor can be spiral, four-leaf clover, or U-shaped; the inner diameter of the tubular reactor is 4.0 - 15.0 mm.

4. The apparatus for continuously preparing pseudo-boehmite according to claim 1, wherein, The heating device is an oven, a water bath, an oil bath, or a sand bath; the heating temperature is 30 - 70 °C.

5. The device for continuously preparing pseudo-boehmite according to claim 1, wherein The vibrating motor is preferably a two-stage vibrating motor.

6. The device for continuously preparing pseudo-boehmite according to claim 1, wherein, The tubular reactor and the vibrating motor are placed on the same platform. The tubular reactor is located inside the heating device, and the vibrating motor is located outside the heating device.

7. A method of applying the device as claimed in claim 1, characterized in that, It includes the following steps: Solutions of raw material 1, raw material 2, and raw material 3 flow in parallel through different feed inlets into the rotating liquid film reactor. Under the shearing force provided by the rotor therein, the three raw materials are mixed to achieve uniform nucleation; the slurry flows out of the discharge outlet of the rotating liquid film reactor and flows into the stirring tank by the potential difference, and then is transported by a pump to the tubular reactor connected to the vibrating motor. After passing through the tubular reactor, a pseudo-boehmite slurry with a uniform particle size distribution is obtained; The above-mentioned raw material 1 is an aqueous solution of aluminum sulfate, aluminum nitrate, aluminum chloride, or a mixture thereof, in which the mass fraction of aluminum is 1.0% - 2.5%. Raw material 2 is an aqueous solution of sodium aluminate, in which the mass fraction of aluminum is 2.0% - 6.0%. Raw material 3 is an aqueous solution of a surfactant, in which the mass fraction of the surfactant is 0.1% - 1.0%; By adjusting the flow rates of raw material 1 and raw material 2, the pH value of the slurry flowing out of the discharge outlet of the rotating liquid film reactor is 8.0 - 10.0, and the flow rate of raw material 3 is equivalent to 5% - 50% of the sum of the flow rates of raw material 1 and raw material 2; The residence time of the slurry in the stirring tank is 10.0 - 30.0 min; The flow rate of the slurry entering the tubular reactor is equal to the sum of the flow rates of the three raw materials, and the residence time of the slurry therein is 1.0 - 5.0 hr.

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