Pseudo-boehmite as well as preparation method and application thereof

Abstract

The invention relates to the field of pseudo-boehmite, and discloses pseudo-boehmite as well as a preparation method and application thereof, the pore volume of the pseudo-boehmite is 0.5-0.7 mL / g, the peptization index DI is 95-99%, and the pore volume retention rate after peptization is greater than 70%. According to the pseudo-boehmite, by controlling reaction conditions and purified water aging conditions, a new weak base environment is provided for crystal growth, particle growth and interaction among particles are adjusted, the pseudo-boehmite with high peptizing property is obtained, the pore volume retention rate after peptizing is relatively high, and the pseudo-boehmite has relatively large pore volume.

Description

Technical Field

[0001] The invention relates to the field of pseudo-boehmite, and in particular to pseudo-boehmite and a preparation method and application thereof. Background Art

[0002] CCUS technologies are emerging in an endless stream, mainly focusing on "carbon-to-chemistry", that is, using carbon dioxide to produce inorganic and organic chemical products, including methanol, formic acid, olefins, aromatics, urea, carbonates, etc.

[0003] However, in the process of preparing pseudo-boehmite by carbonization, low concentration of CO2 easily causes sodium aluminate to undergo hydrolysis reaction (NaAlO2+2H2O→Al(OH)3+NaOH), thereby producing gibbsite impurities. Therefore, in the prior art, the volume concentration of carbon dioxide in preparing pseudo-boehmite by carbonization is mostly above 30%.

[0005] CN111592022A discloses a method for preparing pseudo-boehmite by carbonization, wherein a sodium aluminate solution having a total alkali content of 45-55 g / L, an aluminum oxide content of 40-45 g / L, and a caustic coefficient αk of 1.5-1.7 is used as a raw material, and a volume fraction of 35-40% is introduced at a pressure of 0.85-0.9 kg / cm 2 The carbon dioxide gas is used to age the mother liquor to obtain a pseudo-boehmite product with a peptization index greater than 97%.

[0006] CN110304644A discloses a method for producing high-purity and high-viscosity pseudo-boehmite, which comprises reacting a high-purity sodium aluminate solution with a carbon dioxide gas having a concentration of 30-50% to obtain a high-purity pseudo-boehmite wet filter cake, adding a high-purity hydrated slurry and a high-carbon alcohol additive, and reacting the mixture at 100-200°C and a pressure of 0.5-1MPa for 2-24 hours to obtain a high-purity and high-viscosity pseudo-boehmite having a pore volume of 0.5-0.6mL / g.

[0007] CN102838148B discloses a carbonization reaction device, which adds a self-priming agitator assembly to make the gas distribution uniform, the bubble size small, and the gas utilization rate high, so as to obtain pseudo-boehmite with uniform grain size and concentrated pore size distribution. The invention uses mother liquor aging and CO2 volume concentration of 50%-98% gas.

[0008] CN103449485B discloses a device for producing pseudo-boehmite, which continuously adds sodium aluminate solution into an ejector, and introduces a mixed gas of air and carbon dioxide into the ejector, so that the sodium aluminate solution forms a strong liquid flow and is fully mixed with the carbon dioxide gas, thereby improving production efficiency and maintaining stable product quality. The invention uses mother liquor aging and a gas with a CO2 volume concentration of 80%-100%.

[0009] CN112755936A discloses a device for preparing pseudo-boehmite, which combines a membrane assembly unit and a stirring unit, increases the dispersion of CO2 gas, and makes the gas-liquid mixing more complete. At the same time, the stirring unit can remove the aluminum glue on the surface of the membrane assembly, thereby extending the service life of the membrane assembly, maintaining stable product quality, and long-term operation of the device. The invention uses a gas with a CO2 volume concentration of 10% to 60%, does not mention the aging process, and does not mention the product properties. It is impossible to use a mixed gas with a CO2 volume fraction of less than 10%, and the CO2 capture rate is not described.

[0010] At present, there are the following problems: (1) It is difficult to utilize low-concentration CO2 in the carbonization method for preparing pseudo-boehmite; (2) In order to improve gas utilization and enhance gas-liquid mass transfer, the internal components of the carbonization method for preparing pseudo-boehmite are complex and costly, and it is difficult to take into account the capture rate of low-concentration CO2. Therefore, it is urgent to develop a highly peptized pseudo-boehmite and a method for efficiently utilizing low-concentration CO2 to prepare high-purity pseudo-boehmite. Summary of the invention

[0011] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a pseudo-boehmite and a preparation method and application thereof. The pseudo-boehmite provides a new weak alkaline environment for crystal growth by controlling reaction conditions and water purification aging conditions, regulates particle growth and interaction between particles, and obtains highly peptized pseudo-boehmite. The pore volume retention rate after peptization is high and the pore volume is large.

[0012] In order to achieve the above object, the first aspect of the present invention provides a pseudo-boehmite, wherein the pseudo-boehmite has a pore volume of 0.5-0.7 mL / g, a peptization index DI of 95-99%, and a pore volume retention rate after peptization greater than 70%.

[0013] A second aspect of the present invention provides a method for preparing pseudo-boehmite, wherein the method is carried out in a pseudo-boehmite reaction system, and the reaction system comprises:

[0014] A column reactor is used to contact the sodium aluminate solution with a CO2 gas source to perform a gelling reaction;

[0015] The height-to-diameter ratio of the reactor is ≥3;

[0016] At least one porous partition is provided inside the reactor;

[0017] The preparation method comprises:

[0018] (1) introducing a CO2 gas source into a column reactor through an air inlet to react with the sodium aluminate solution in the reactor to form a gel, and stopping the gel reaction when the pH value of the solution is 9-11;

[0019] (2) mixing the filtered solid from the slurry of step (1) with deionized water for aging reaction to obtain pseudo-boehmite;

[0020] The mass ratio of the deionized water to the mass ratio of the sodium aluminate in terms of alumina added in the gelling reaction is 25-90.

[0021] The third aspect of the present invention provides pseudo-boehmite obtained by the preparation method described in the second aspect.

[0022] A fourth aspect of the present invention provides an application of the pseudo-boehmite described in the first aspect or the third aspect in the field of petrochemical industry.

[0023] Through the above technical solution, the beneficial effects obtained are as follows:

[0024] (1) The pseudo-boehmite provided by the present invention is obtained by controlling the reaction conditions such as pH value, reactant concentration, CO2 gas source superficial gas velocity and clean water aging conditions to obtain highly peptized pseudo-boehmite, which has a high pore volume retention rate after peptization and a large pore volume;

[0025] (2) The pseudo-boehmite preparation method provided in the present invention adopts a clean water aging method, and the aging is carried out at high temperature to provide a new weak alkaline environment for crystal growth, regulate particle growth and the interaction between particles, and promote crystal growth. The above pseudo-boehmite reaction system can make the CO2 capture rate not less than 50%;

[0026] (3) In the present invention, the pseudo-boehmite provided has good peptization solubility and high pore volume retention after peptization, and can be widely used in the field of petrochemical industry, especially as a binder for catalytic cracking catalysts. It can enrich the medium and macropore structure in the catalyst while improving the strength of the catalyst, enhance the conversion of heavy oil, improve the product distribution of residual oil cracking, and improve the economic benefit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the pseudo-boehmite reaction system.

[0028] Description of Reference Numerals

[0029] 1-Sodium aluminate inlet 2-Reaction chamber 3-CO2 gas source inlet

[0030] 4-conical air chamber 5-porous partition 6-air inlet (only one is marked)

[0031] 7-Detection port 8-Exhaust port 9-Discharge port DETAILED DESCRIPTION

[0032] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0033] A first aspect of the present invention provides a pseudo-boehmite, wherein the pseudo-boehmite has a pore volume of 0.5-0.7 mL / g, a peptization index DI of 95-99%, and a pore volume retention rate after peptization greater than 70%.

[0034] According to the present invention, preferably, the pore volume of the pseudo-boehmite is 0.5-0.7 mL / g, such as 0.5 mL / g, 0.55 mL / g, 0.6 mL / g, 0.65 mL / g, 0.7 mL / g, or any range therebetween, 0.55-0.7 mL / g. The pseudo-boehmite has a larger pore volume.

[0035] In the present invention, the pore volume of the pseudo-boehmite is determined by the BET method, using the ASAP 2405N V1.01 automatic adsorption instrument of Micromeritics Company of the United States, and the low temperature static nitrogen adsorption capacity method. -2 The sample was vacuum degassed at 300°C for 4 h, and N2 was used as the adsorption medium to measure the adsorption-desorption isotherm of the sample at 77.4 K. The specific surface area (SBET) of the sample was calculated according to the BET formula, and the volume of N2 adsorbed by the sample at the relative pressure p / p0=0.98 was measured and converted into liquid nitrogen volume, i.e., pore volume.

[0036] According to the present invention, preferably, the peptization index DI of the pseudo-boehmite is 97-99%.

[0037] In the present invention, the peptization index (DI) is determined by the following method: weigh 10 grams of pseudo-boehmite, roast it at 600°C for 3 hours, cool it in a desiccator, and after the temperature drops to room temperature, weigh W0 grams to obtain a solid content a0=W0 / 10, weigh the weight of pseudo-boehmite m1=10 / a0 grams, put the weighed m1 gram of pseudo-boehmite in a beaker, add deionized water to a slurry mass concentration of 10%, stir evenly, then add 1.8 g of dilute hydrochloric acid (mass concentration 36%), stir for 20 minutes, pour all the solution into a centrifuge tube, put it in a centrifuge, and centrifuge it at a speed of 2000 rpm for 20 minutes. Pour out the upper colloidal solution, put it in a weighed crucible, dry it at 80℃ for 24 hours, then roast it at 600℃ for 3 hours, cool it in a desiccator, and after the temperature drops to room temperature, weigh it to get m2 grams. The peptization index DI = (m2 / 10)*100%.

[0038] According to the present invention, preferably, the pore volume retention rate of the pseudo-boehmite after peptization is greater than 70%, preferably 75-82%. In the present invention, the pore volume retention rate after peptization refers to the ratio of the pore volume of the pseudo-boehmite after peptization to the pore volume of the pseudo-boehmite before peptization. In the present invention, the pseudo-boehmite has a high pore volume retention rate after peptization and has a stable macroporous structure.

[0039] In the present invention, the peptization conditions are as follows: the pseudo-boehmite sample is mixed with deionized water to form a slurry with a mass concentration of 10%, and the mixture is stirred at room temperature according to n(H + ) / n(Al2O3)=0.2, add hydrochloric acid to the pseudo-boehmite sample and stir for 20 minutes.

[0040] According to the present invention, preferably, in the IR spectrum 3600-3800cm -1 The value of the hydroxyl peak integrated area per mg of pseudo-boehmite sample is not less than 2, preferably 2 to 3. In the present invention, the hydroxyl peak integrated area per mg of pseudo-boehmite sample meets the above definition, which can ensure that the pseudo-boehmite sample has excellent peptization performance.

[0041] In the present invention, the IR spectrum is obtained by measuring the IR spectrum using a Nicolet 870 Fourier infrared spectrometer from Nicolet, USA. Specifically, the sample is pressed into a self-supporting sheet, placed in an infrared cell, treated at 450°C for 3 hours under vacuum conditions, and the infrared spectrum of the sample is measured. -1 The surface hydroxyl peaks in the range of 3600-3800 cm -1 A baseline is drawn within the range, and after baseline correction, the area enclosed by the baseline and the spectrum curve is taken as the peak area of ​​the hydroxyl peak.

[0042] According to the present invention, preferably, the pore volume of the pseudo-boehmite after peptization is 0.4-0.55 mL / g.

[0043] According to the present invention, preferably, the relative crystallinity of the pseudo-boehmite is 75-98%, preferably 80-95%.

[0044] In the present invention, the relative crystallinity and grain size of the pseudo-boehmite are measured by X-ray powder diffraction (XRD) using RIPP145-90 and RIPP146-90 standard methods (see "Petrochemical Analysis Methods" (RIPP Test Methods) edited by Yang Cuiding et al., Science Press, published in 1990). The grain size calculation formula is: Wherein K=1.075, λ is the wavelength of the anode radiation Kα1 spectrum line, β1 is the integrated width of the diffraction peak of the (130) crystal plane of pseudo-boehmite, and θ is the Bragg diffraction angle of the diffraction peak.

[0045] In the present invention, preferably, the pseudo-boehmite has high purity, and the content of alumina trihydrate heterocrystalline phase in the pseudo-boehmite is less than 1wt%, preferably without a gibbsite heterocrystalline phase. The content of alumina trihydrate heterocrystalline phase in the pseudo-boehmite is determined according to RIPP138-90 alumina trihydrate heterocrystalline phase content.

[0046] A second aspect of the present invention provides a method for preparing pseudo-boehmite, wherein the method is carried out in a pseudo-boehmite reaction system, and the reaction system comprises:

[0047] A column reactor is used to contact the sodium aluminate solution with a CO2 gas source to perform a gelling reaction;

[0048] The height-to-diameter ratio of the reactor is ≥3;

[0049] At least one porous partition is provided inside the reactor;

[0050] The preparation method comprises:

[0051] (1) introducing a CO2 gas source into a column reactor through an air inlet to react with the sodium aluminate solution in the reactor to form a gel, and stopping the gel reaction when the pH value of the solution is 9-11;

[0052] (2) mixing the filtered solid from the slurry of step (1) with deionized water for aging reaction to obtain pseudo-boehmite;

[0053] The mass ratio of the deionized water to the mass ratio of the sodium aluminate in terms of alumina added in the gelling reaction is 25-90.

[0054] In the present invention, the preparation method of the pseudo-boehmite adopts a clean water aging method, and the aging is carried out at high temperature to provide a new weak alkaline environment for crystal growth, regulate particle growth and interaction between particles, and promote crystal growth. The preparation using the pseudo-boehmite reaction system can make the CO2 capture rate not less than 50%.

[0055] In the present invention, the pseudo-boehmite reaction system has a simple equipment structure and occupies a small area. The porous baffles can, on the one hand, break up bubbles, reduce bubble size, increase gas-liquid contact area, and enhance mass transfer; on the other hand, the porous baffles can effectively prolong the residence time of CO2 gas in the liquid phase under high gas velocity conditions, increase gas content and effectively improve CO2 capture rate.

[0056] According to the present invention, the air inlet holes are evenly distributed on the porous baffle, and the number of air inlet holes on each porous baffle is not particularly limited. Those skilled in the art can calculate and determine it based on the diameter of the column reactor, the aperture of the air inlet holes, and the spacing between the air inlet holes. Preferably, the number of the air inlet holes is ≥2. According to the present invention, preferably, the geometric center spacing between any two adjacent air inlets is not less than 2.5 times their maximum diameters. The maximum diameter refers to the corresponding diameter of the air inlet with the larger diameter of the two adjacent air inlets. The geometric center spacing refers to the straight-line distance between the geometric center positions of the corresponding air inlets. Preferably, the geometric center spacing between any two adjacent air inlets is not greater than 5 times their maximum diameters.

[0057] According to the present invention, preferably, the aperture of the air inlet holes of the porous partition is independently 3-10 mm, such as 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any range therebetween, preferably 5-8 mm. In the present invention, the air inlet holes are arranged in the above preferred manner, so that the CO2 gas source can break the bubbles when passing through the porous partition, reduce the bubble size, increase the gas-liquid contact area, and enhance mass transfer.

[0058] According to the present invention, preferably, the column reactor is a multi-section column reactor. The use of a multi-section column reactor can reduce the footprint of the device and reduce production investment.

[0059] According to the present invention, preferably, an air inlet and a conical air chamber are further provided at the bottom of the reactor. The air inlet is connected to the conical air chamber whose cross section gradually increases upward, and the top of the conical air chamber is connected to the reaction chamber of the reactor. By adopting the above embodiment, the CO2 gas source can be fully contacted with the sodium aluminate solution, and the gelling reaction is more thorough.

[0060] According to the present invention, the cone angle of the conical air chamber is not particularly limited, as long as the purpose of the present invention can be achieved. Preferably, the cone angle of the conical air chamber is 50-70°.

[0061] According to the present invention, the height-to-diameter ratio of the column reactor is not particularly limited, and those skilled in the art can adjust it adaptively according to the number of porous baffles. Preferably, the height-to-diameter ratio of the column reactor is 4-10. In the present invention, the height-to-diameter ratio refers to the ratio of the height direction of the column reactor to the reactor diameter, and the reactor diameter refers to the diameter of the cross section of the column reactor, and the cross-sectional size of the column reactor is consistent. The reactor diameter is not particularly limited, and those skilled in the art can adjust it adaptively according to the reactant feed amount and the column reactor capacity.

[0062] According to the present invention, preferably, the porous partition is circular. Preferably, the porous partition is arranged perpendicular to the inlet direction of the CO2 gas source, the circular porous partition is connected to the inner wall of the reactor, and the number of the porous partitions is 2-5. In the present invention, the porous partition can prolong the residence time of the CO2 gas source in the liquid phase under high gas velocity conditions, thereby increasing the gas holdup and CO2 capture rate.

[0063] According to the present invention, preferably, the distance between any two adjacent porous baffles satisfies: 2 times the reactor diameter ≤ porous baffle spacing ≤ 3 times the reactor diameter. In the present invention, the distance between any two adjacent porous baffles is controlled to meet the above range, which can improve the CO2 capture rate while ensuring uniform reaction.

[0064] In the present invention, the porous partition closest to the air inlet is arranged at the place where the top of the conical air chamber is connected to the reaction chamber, and other arrangement positions are not particularly limited as long as the spacing is met.

[0065] In the present invention, the column reactor is provided with a sodium aluminate inlet connected to the reaction chamber for adding a sodium aluminate solution into the column reactor; wherein the position of the sodium aluminate inlet on the column reactor is not particularly limited, as long as the sodium aluminate solution can be added.

[0066] According to the present invention, in some embodiments, the column-type reactor is provided with a detection port connected to the reaction chamber for monitoring the reaction temperature and reaction progress of the reaction system; wherein, those skilled in the art can understand that, when conducting a gelling reaction, the reaction progress can be reflected by the pH value of the reaction system, that is, the detection port can detect the pH value.

[0067] In the present invention, the "reaction system" refers to a system for carrying out a reaction in the reaction chamber of the column-type reactor of the reaction system of the present invention, which is a gel-forming reaction in the present invention.

[0068] According to the present invention, in some embodiments, the column-type reactor is provided with a discharge port connected to the reaction chamber for removing the reaction material finally obtained from the reaction system.

[0069] According to the present invention, in some embodiments, the column reactor is provided with an exhaust port connected to the reaction chamber for the series connection of multiple reaction systems and / or the discharge of unreacted gas materials. When using the reaction system of the present invention to prepare pseudo-boehmite, part of the CO2 gas source may not be fully reacted. By adopting this embodiment, the utilization rate of the CO2 gas source can be further improved.

[0070] According to the present invention, it can be understood that when multiple reaction systems are used in series, the exhaust port in the previous reaction system is connected to the CO2 gas source inlet assembly of the subsequent reaction system.

[0071] According to the present invention, preferably, in the aging reaction, the mass ratio of the deionized water to the mass ratio of the sodium aluminate in terms of alumina added in the gelling reaction is 25-90, such as 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, preferably 30-70. In the present invention, adding too much deionized water will reduce the pore volume of the pseudo-boehmite, and too little will affect the peptization performance.

[0072] According to the present invention, preferably, the conditions of the aging reaction include: a temperature not less than 100°C, preferably 100-120°C; an aging time of 120-280 minutes, preferably 180-240 minutes. Aging under the above high temperature conditions can promote particle growth and obtain pseudo-boehmite with a higher pore volume retention rate after peptization.

[0073] According to the present invention, preferably, the CO2 gas source has an apparent gas velocity of 0.6-12 cm / s, such as 0.6 cm / s, 1.2 cm / s, 1.5 cm / s, 1.8 cm / s, 2 cm / s, 2.1 cm / s, 2.4 cm / s, 3 cm / s, 4 cm / s, 5 cm / s, 6 cm / s, 7 cm / s, 8 cm / s, 9 cm / s, 10 cm / s, 12 cm / s, or any range therebetween. For example, for a reactor having a diameter of 10 cm and a height-to-diameter ratio of 3-10, the apparent gas velocity is 1.2-2.5 cm / s. In the present invention, those skilled in the art can adapt the apparent gas velocity of the CO2 gas source according to the reactor diameter.

[0074] In the present invention, the term "superficial gas velocity" refers to the ratio of the gas flow rate to the cross-sectional area of ​​the column-type reactor.

[0075] According to the present invention, preferably, the volume concentration of CO2 in the CO2 gas source is not greater than 20%, preferably 5-20%. In the present invention, the volume of gas refers to the volume under standard conditions.

[0076] According to the present invention, preferably, the CO2 gas source is prepared from high-concentration CO2 gas; wherein, high-concentration CO2 gas refers to a gas in which the volume concentration of CO2 in the gas is greater than 20%.

[0077] According to the present invention, in some embodiments, the CO2 gas source comes from industrial flue gas. The industrial flue gas mainly contains N2 and CO2, and may contain a small amount of SO x 、NO x , O2 and very little dust and other components; exemplified industrial flue gases include FCC regeneration flue gas, thermal power plant flue gas, steel plant flue gas, flue gas generated by boilers, flue gas generated by combustion furnaces and flue gas generated by calcining furnaces, etc.; preferably, the industrial flue gas is washed industrial flue gas, specifically, the industrial flue gas is washed by a flue gas washing tower, and the washing method is a conventional method in the field, which will not be described in detail in the present invention.

[0078] In the present invention, CO2 in industrial flue gas is used to prepare pseudo-boehmite, which can reduce CO2 gas emissions and reduce the cost of preparing pseudo-boehmite, thereby realizing resource utilization of CO2 gas. Usually, the concentration of CO2 gas in industrial flue gas is lower than 20%, which is lower than the value that can be achieved by the carbonization method in the prior art. By adopting the preparation method of the present invention, high-purity, high-peptized pseudo-boehmite can be prepared under the condition of low CO2 gas concentration, and the CO2 capture rate is not less than 50%.

[0079] According to the present invention, preferably, the mass concentration of the sodium aluminate solution is 5-40 g / L, such as 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, or any range therebetween, preferably 15-40 g / L, in terms of Al2O3. In the present invention, the sodium aluminate solution refers to a solution formed by mixing sodium aluminate with water.

[0080] According to the present invention, the conditions of the gelation reaction are not particularly limited. According to a preferred embodiment of the present invention, the conditions of the gelation reaction include: a reaction temperature lower than 50°C, for example, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or any range therebetween, preferably 5-40°C.

[0081] According to the present invention, in some embodiments, the conditions of the gelling reaction include: the end point of the gelling reaction is a pH value of 9-11; wherein, it is understood that when the gelling reaction reaches the end point, the introduction of the CO2 gas source can be stopped. In the present invention, the pH value of the gelling reaction solution is not easy to be too low, and a low pH value is easy to cause the formation of dawsonite, which is difficult to remove in the subsequent process; the pH value of the gelling reaction solution is not easy to be too high, which is easy to cause the formation of gibbsite impurities.

[0082] According to the present invention, it is understandable that the reaction mass obtained by the aging reaction may contain some impurities (such as sodium ions). In order to obtain high-quality pseudo-boehmite dry powder, in some embodiments, the preparation method further includes: washing and drying the solid matter in the reaction mass obtained by the aging reaction.

[0083] According to the present invention, there is no particular limitation on the method of obtaining the solid matter in the reaction mass obtained by the aging reaction, for example, the solid matter can be obtained by filtration. According to one embodiment of the present invention, the end point of the washing is: the pH value of the water after washing is 7-7.5.

[0084] According to the present invention, as long as the purpose of the present invention can be achieved, the drying method and conditions are not particularly limited. In some embodiments, the drying conditions include: a drying temperature of 60-120°C, preferably 70-100°C, and / or a drying time of 2-6 hours, preferably 2-4 hours.

[0085] According to the present invention, there may still be some unreacted CO2 gas sources in the reaction system, which can be discharged from the exhaust port. In order to further improve the utilization rate of the CO2 gas source, in some embodiments, the preparation method also includes introducing the unreacted CO2 gas source discharged from the exhaust port into the corresponding reaction system through the CO2 gas source intake assembly of the next reaction system to continue to contact with the sodium aluminate solution in the column reactor in the next reaction system to carry out a gelation reaction.

[0086] In the present invention, the pseudo-boehmite is prepared by the above preparation method, and the CO2 capture rate is high, and the CO2 capture rate is ≥50%.

[0087] In the present invention, the CO2 capture rate is calculated by the following formula:

[0088]

[0089] The third aspect of the present invention provides pseudo-boehmite obtained by the preparation method described in the second aspect.

[0090] A fourth aspect of the present invention provides an application of the pseudo-boehmite described in the first aspect or the third aspect in the field of petrochemical industry.

[0091] According to the present invention, preferably, the pseudo-boehmite is used in the field of catalytic cracking catalysts.

[0092] In the present invention, the pseudo-boehmite has good peptization solubility and high pore volume retention after peptization, and can be widely used in the field of petrochemical industry, especially as a binder for catalytic cracking catalysts. It can enrich the medium and macropore structure in the catalyst while improving the strength of the catalyst, enhance the conversion of heavy oil, improve the product distribution of residual oil cracking, and improve the economic benefit.

[0093] According to a preferred embodiment of the present invention, the preparation of the pseudo-boehmite is Figure 1 In the reaction system, sodium aluminate solution is added into the reaction chamber 2 through the sodium aluminate inlet 1, and the CO2 gas source enters the reaction chamber 2 through the CO2 gas source inlet 3 and the conical gas chamber 4 in turn. The CO2 gas source breaks the bubbles through the inlet hole 6 on the porous partition 5 and reacts with the sodium aluminate solution to form a gel. The pH and temperature of the solution in the reaction chamber 2 are monitored through the detection port 7. When the pH is 9-11, the CO2 gas source is stopped from being introduced. The unreacted CO2 gas source is discharged through the exhaust port 8. The slurry after the reaction is transferred to the aging kettle through the discharge port 9 for aging. The aged slurry is filtered, washed and dried to obtain pseudo-boehmite dry powder.

[0094] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, all reagents used are commercially available, and the room temperature is 25°C;

[0095] The test methods for the crystallinity, specific surface area and pore volume of pseudo-boehmite, the test method for the trihydrate impurity content, the peptization index, and the calculation method for the CO2 capture rate are described in the aforementioned specification and will not be repeated here.

[0096] Example 1

[0097] like Figure 1 As shown, the reactor used in the embodiment has a height-to-diameter ratio of 5, a volume of 4.15 L (including a conical air chamber), a cone angle of the conical air chamber of 60°, a reactor diameter of 10 cm, and the reactor is provided with 3 porous partitions. The distance between two adjacent porous partitions is 2 times the diameter of the reactor. Each porous partition is provided with 19 air inlet holes, and the aperture of the air inlet holes is 6 mm. The geometric center distance between any two adjacent air inlet holes is 17.5 mm.

[0098] A sodium aluminate solution with a mass concentration of 10g / L (in terms of Al2O3) is added to the reaction chamber 2 through the sodium aluminate inlet 1, and a CO2 gas source (CO2 volume concentration of 5%, the rest is nitrogen) enters the reaction chamber 2 through the CO2 gas source inlet 3 and the conical gas chamber 4 in turn. The apparent gas velocity of the CO2 gas source is 1.6cm / s. The CO2 gas source breaks the bubbles through the inlet 6 on the porous partition 5, and reacts with the sodium aluminate solution to form a gel at room temperature. The pH of the solution in the reaction chamber 2 is monitored through the detection port 7. When the pH is 10.5, the CO2 gas source is stopped. The slurry after the reaction is transferred to the aging kettle through the discharge port 9 for aging, the reaction slurry is separated into solid and liquid, and deionized water 70 times the mass of aluminum oxide in the sodium aluminate solution is added to the wet filter cake, stirred evenly, and aged for 3 hours at 100°C. After aging, the slurry was filtered and washed until the pH value of the washed water was 7. The filter cake was dried at 100° C. for 3 hours to obtain pseudo-boehmite A1. The properties are shown in Table 1. The unreacted CO2 gas source was discharged through the exhaust port 8.

[0099] Example 2

[0100] use Figure 1 A reaction system is prepared, wherein a sodium aluminate solution with a concentration of 25 g / L (in terms of Al2O3) is added to the reaction chamber 2 through the sodium aluminate inlet 1, and a CO2 gas source (CO2 volume concentration is 10%, and the rest is nitrogen) enters the reaction chamber 2 through the CO2 gas source inlet 3 and the conical gas chamber 4 in turn. The superficial gas velocity of the CO2 gas source is 2.2 cm / s. The CO2 gas source breaks the bubbles through the inlet 6 on the porous partition 5, and reacts with the sodium aluminate solution to form a gel at room temperature. The pH of the solution in the reaction chamber 2 is monitored through the detection port 7. When the pH is 10.2, the CO2 gas source is stopped from being introduced. The unreacted CO2 gas source is discharged through the exhaust port 8. The slurry after the reaction is transferred to the aging kettle through the discharge port 9 for aging, the reaction slurry is subjected to solid-liquid separation, and deionized water 50 times the mass of alumina in the sodium aluminate solution is added to the wet filter cake, stirred evenly, and aged at 100°C for 4 hours. After aging, the slurry was filtered and washed until the pH value of the washed water was 7. The filter cake was dried at 100° C. for 3 hours to obtain pseudo-boehmite A2, whose physicochemical properties are shown in Table 1.

[0101] Example 3

[0102] use Figure 1A reaction system is prepared, wherein a sodium aluminate solution with a concentration of 35 g / L (in terms of Al2O3) is added to the reaction chamber 2 through the sodium aluminate inlet 1, and a CO2 gas source (CO2 volume concentration is 15%, and the rest is nitrogen) enters the reaction chamber 2 through the CO2 gas source inlet 3 and the conical gas chamber 4 in turn. The superficial gas velocity of the CO2 gas source is 2 cm / s. The CO2 gas source breaks the bubbles through the inlet 6 on the porous partition 5, and reacts with the sodium aluminate solution to form a gel at room temperature. The pH of the solution in the reaction chamber 2 is monitored through the detection port 7. When the pH is 10, the CO2 gas source is stopped from being introduced. The unreacted CO2 gas source is discharged through the exhaust port 8. The slurry after the reaction is transferred to the aging kettle through the discharge port 9 for aging, the reaction slurry is subjected to solid-liquid separation, and deionized water 35 times the mass of alumina in the sodium aluminate solution is added to the wet filter cake, stirred evenly, and aged for 3 hours at 110°C in purified water. After aging, the slurry was filtered and washed until the pH value of the washed water was 7. The filter cake was dried at 100° C. for 3 hours to obtain pseudo-boehmite A3, whose physicochemical properties are shown in Table 1.

[0103] Example 4

[0104] use Figure 1 A reaction system is prepared, wherein a sodium aluminate solution with a concentration of 40 g / L (in terms of Al2O3) is added to the reaction chamber 2 through the sodium aluminate inlet 1, and a CO2 gas source (CO2 volume concentration is 20%, and the rest is nitrogen) enters the reaction chamber 2 through the CO2 gas source inlet 3 and the conical gas chamber 4 in turn. The superficial gas velocity of the CO2 gas source is 1.8 cm / s. The CO2 gas source breaks the bubbles through the inlet hole 6 on the porous partition 5, and reacts with the sodium aluminate solution to form a gel at room temperature. The pH of the solution in the reaction chamber 2 is monitored through the detection port 7. When the pH is 10, the CO2 gas source is stopped from being introduced. The unreacted CO2 gas source is discharged through the exhaust port 8. The slurry after the reaction is transferred to the aging kettle through the discharge port 9 for aging, the reaction slurry is subjected to solid-liquid separation, and deionized water 30 times the mass of alumina in the sodium aluminate solution is added to the wet filter cake, stirred evenly, and aged at 120°C for 4 hours. After aging, the slurry was filtered and washed until the pH value of the washed water was 7. The filter cake was dried at 100° C. for 3 hours to obtain pseudo-boehmite A4, whose physicochemical properties are shown in Table 1.

[0105] Example 5

[0106] Pseudo-boehmite was prepared according to the method of Example 3, except that two porous baffles were provided in the column reactor (one was still provided at the place where the top of the conical gas chamber was connected to the reaction chamber, and the other was provided at a height-to-diameter ratio of 3 from the place where the top of the conical gas chamber was connected to the reaction chamber), to obtain pseudo-boehmite A5, whose physicochemical properties are shown in Table 1.

[0107] Comparative Example 1

[0108] Pseudo-boehmite was prepared according to the method of Example 3, except that the reactor was not provided with a porous baffle, to obtain pseudo-boehmite D1, the physicochemical properties of which are shown in Table 1.

[0109] Comparative Example 2

[0110] Pseudo-boehmite was prepared according to the method of Example 3, except that the reactor was not provided with a porous baffle and the superficial gas velocity of the CO2 gas source was 1 cm / s, to obtain pseudo-boehmite D2, the physicochemical properties of which are shown in Table 1.

[0111] Comparative Example 3

[0112] Pseudo-boehmite was prepared according to the method of Example 3, except that the amount of water used for aging was 20 times the mass of the feed alumina. Pseudo-boehmite D3 was obtained, and its physicochemical properties are shown in Table 1.

[0113] Comparative Example 4

[0114] Pseudo-boehmite was prepared according to the method of Example 3, except that the amount of water used for aging was 100 times the mass of the feed alumina. Pseudo-boehmite D4 was obtained, and its physicochemical properties are shown in Table 1.

[0115] Comparative Example 5

[0116] Commercially available macroporous aluminum stone (purchased from Shandong Aluminum, with a macroporous pore volume of 0.6 mL / g) was used as D5, and its physicochemical properties are shown in Table 1.

[0117] Table 1

[0118]

[0119] Note: The value of the integrated area is the value of the integrated area of ​​the hydroxyl peak per mg of pseudo-boehmite sample.

[0120] It can be seen from the results in Table 1 that the pseudo-boehmite provided by the present invention is prepared using a low-concentration carbon dioxide gas source as a raw material, and the reaction system and the preparation method are improved. The obtained pseudo-boehmite has a large pore volume, good peptization solubility, a high pore volume retention rate after peptization, and a CO2 capture rate of not less than 50%.

[0121] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A pseudo-boehmite, characterized in that: The pseudo-boehmite has a pore volume of 0.5-0.7 mL / g, a peptization index DI of 95-99%, and a pore volume retention rate of more than 70% after peptization.

2. The pseudo-boehmite according to claim 1, wherein: The pore volume of the pseudo-boehmite is 0.55-0.7 mL / g; Preferably, the peptization index DI of the pseudo-boehmite is 97-99%; Preferably, the pore volume retention rate of the pseudo-boehmite after peptization is 75-82%; Preferably, in the IR spectrum 3600-3800cm -1 The value of the integrated area of ​​the hydroxyl peak per mg of pseudo-boehmite sample is not less than 2, preferably 2-3; Preferably, the pore volume of the pseudo-boehmite after peptization is 0.4-0.55 mL / g.

3. A method for preparing pseudo-boehmite, characterized in that: The method is carried out in a pseudo-boehmite reaction system, and the reaction system comprises: A column reactor is used to contact the sodium aluminate solution with a CO2 gas source to perform a gelling reaction; The height-to-diameter ratio of the reactor is ≥3; At least one porous partition is provided inside the reactor; The preparation method comprises: (1) introducing a CO2 gas source into a column reactor through an air inlet to react with the sodium aluminate solution in the reactor to form a gel, and stopping the gel reaction when the pH value of the solution is 9-11; (2) mixing the filtered solid from the slurry of step (1) with deionized water for aging reaction to obtain pseudo-boehmite; The mass ratio of the deionized water to the mass ratio of the sodium aluminate in terms of alumina added in the gelling reaction is 25-90.

4. The preparation method according to claim 3, wherein The porous partition is also provided with at least one air inlet hole, preferably, the number of the air inlet holes is ≥2; Preferably, the apertures of the air inlet holes of the porous partition are independently 3-10 mm, preferably 5-8 mm; Preferably, the geometric center distance between any two adjacent air inlet holes is not less than 2.5 times their maximum diameters.

5. The preparation method according to claim 3 or 4, wherein The column reactor is a multi-section column reactor; Preferably, an air inlet and a conical air chamber are also provided at the bottom of the reactor; Preferably, the cone angle of the conical air chamber is 50-70°; Preferably, the height-to-diameter ratio of the column reactor is 4-10.

6. The preparation method according to any one of claims 3 to 5, wherein: The porous partition is circular; Preferably, the number of the porous partitions is 2-5; Preferably, the distance between any two adjacent porous partitions satisfies: 2 times the reactor diameter ≤ the distance between the porous partitions ≤ 3 times the reactor diameter.

7. The preparation method according to any one of claims 3 to 6, wherein: The superficial gas velocity of the CO2 gas source is 0.6-12 cm / s; Preferably, the volume concentration of CO2 in the CO2 gas source is not greater than 20%, preferably 5-20%; Preferably, the low-concentration CO2 gas is prepared by mixing high-concentration CO2 gas and / or comes from industrial flue gas; Calculated in terms of Al2O3, the mass concentration of the sodium aluminate solution is 5-40 g / L, preferably 15-40 g / L.

8. The preparation method according to any one of claims 3 to 7, wherein: The conditions of the gelling reaction include: the reaction temperature is less than 50°C, preferably 5-40°C; Preferably, in the aging reaction, the ratio of the mass of deionized water to the mass of aluminum oxide in the sodium aluminate solution added during the gelling reaction is 30-70; Preferably, the conditions of the aging reaction include: a temperature not less than 100° C., preferably 100-120° C.; and an aging time of 120-280 minutes, preferably 180-240 minutes.

9. The preparation method according to any one of claims 3 to 8, wherein: The preparation method further comprises: washing and drying the solid matter in the reaction material obtained by the aging reaction; Preferably, the end point of the washing is: the pH value of the water after washing is 7-7.5; Preferably, the drying conditions include: a drying temperature of 60-120° C., preferably 70-100° C., and / or a drying time of 2-6 hours, preferably 2-4 hours.

10. Pseudo-boehmite obtained according to the preparation method according to any one of claims 3 to 9.

11. Application of the pseudo-boehmite according to any one of claims 1 to 2 and 10 in the field of petrochemical industry; Preferably, the pseudo-boehmite is used in the field of catalytic cracking catalysts.

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