Pseudo-boehmite, preparation method and application thereof, and pseudo-boehmite reaction system

Abstract

The invention relates to the field of pseudo-boehmite, and discloses pseudo-boehmite, a preparation method and application thereof, and a pseudo-boehmite reaction system, the R value of the pseudo-boehmite is greater than or equal to 1.3 and less than or equal to 1.6, R = D (130) / D (020), D (130) represents the grain size of a crystal face represented by a 130 peak in an XRD spectrogram of pseudo-boehmite grains, and D (020) represents the grain size of the crystal face represented by the 130 peak in the XRD spectrogram of the pseudo-boehmite grains. D (020) represents the grain size of a crystal face represented by a 020 peak in an XRD (X-Ray Diffraction) spectrogram of pseudo-boehmite grains, and the pore volume of the pseudo-boehmite is 0.6-0.9 mL / g; the specific surface area of the pseudo-boehmite is greater than or equal to 420 m < 2 > / g. According to the pseudo-boehmite, the growth speed of crystal grains on a crystal face represented by a 130 peak and a crystal face represented by a 020 peak is adjusted, so that the pseudo-boehmite with a specific crystal grain size is obtained, and meanwhile, the pseudo-boehmite has high specific surface area and 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, and a pseudo-boehmite reaction system. Background Art

[0002] CCUS (Carbon Capture, Utilization and Storage) is a technology for carbon capture, utilization and storage. CCUS technology can store carbon dioxide emitted during the production process, or purify it and put it into a new production process for recycling. CCUS technology turns carbon dioxide into resources, generates economic benefits, and is beneficial to the environment. 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] The total amount of carbon emissions in flue gas from the petroleum refining industry, power industry, steel industry, etc. is large, but the concentration of carbon dioxide in these industrial flue gases is mostly below 20%, and "carbon one chemistry" has high requirements for the purity of CO2. The use of CO2 in industrial flue gas needs to be purified and purified, which is costly. If the carbon dioxide in industrial flue gas is used for the carbonization method to prepare pseudo-boehmite, it will be low-cost, green and environmentally friendly, meet the requirements of the era of carbon reduction development, and achieve a win-win situation of carbon dioxide emission reduction and resource utilization.

[0004] 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 reacted at about 30°C to form a gel, thereby obtaining a pseudo-boehmite product with a gelling index greater than 97%.

[0006] CN110304644A discloses a method for producing high-purity and high-viscosity pseudo-boehmite, wherein a high-purity sodium aluminate solution is reacted with a carbon dioxide gas with a concentration of 30-50% at 25°C-30°C to obtain a high-purity pseudo-boehmite wet filter cake, and then a high-carbon alcohol additive is added to the slurry to react 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 with a pore volume of 0.5-0.6mL / g and a specific surface area of ​​less than 300m 2 / g.

[0007] CN102838148A discloses a carbonization reaction device, which is equipped with 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 device has a gelling temperature of 15-35°C and uses a gas with a CO2 volume concentration of 50%-98%.

[0008] CN103449485A discloses a device for producing pseudo-boehmite, which continuously adds a 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 slurry temperature generated by the gelling reaction of the device is 25-55°C, and the CO2 volume concentration is 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, makes the gas-liquid mixing more complete, and at the same time, because the stirring unit can remove the aluminum glue on the surface of the membrane assembly, the service life of the membrane assembly is extended, the product quality is maintained stable, and the device operates for a long period of time. The device uses gas with a CO2 volume concentration of 10%-60%. The product properties are not mentioned, and mixed gas with a CO2 volume fraction of less than 10% cannot be used, and the CO2 capture rate is not explained.

[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 device or system and 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 problems existing in the above-mentioned prior art and to provide a pseudo-boehmite and its preparation method and application, and a pseudo-boehmite reaction system. The pseudo-boehmite is obtained by adjusting the growth rate of the grains on the crystal plane represented by the 130 peak and the crystal plane represented by the 020 peak to obtain pseudo-boehmite of a specific grain size, and at the same time has a high specific surface area and a large pore volume.

[0012] In order to achieve the above-mentioned object, the first aspect of the present invention provides a pseudo-boehmite, wherein the R value of the pseudo-boehmite satisfies 1.3≤R≤1.6, wherein R=D(130) / D(020), the D(130) represents the grain size of the crystal plane represented by the 130 peak in the XRD spectrum of the pseudo-boehmite grains, and the D(020) represents the grain size of the crystal plane represented by the 020 peak in the XRD spectrum of the pseudo-boehmite grains, the 130 peak refers to the peak with 2θ of 34-43° in the XRD spectrum, and the 020 peak refers to the peak with 2θ of 10-15° in the XRD spectrum;

[0013] The pore volume of the pseudo-boehmite is 0.6-0.9 mL / g;

[0014] The specific surface area of ​​the pseudo-boehmite is ≥420m 2 / g.

[0015] A second aspect of the present invention provides a pseudo-boehmite reaction system, wherein the reaction system comprises:

[0016] A column reactor is used to contact the sodium aluminate solution with a CO2 gas source to perform a gelling reaction;

[0017] The height-to-diameter ratio of the reactor is ≥3;

[0018] At least one porous partition is provided inside the reactor;

[0019] The porous partition is also provided with at least one air inlet hole;

[0020] The diameter of the air inlet holes of the porous partition is independently 3-10 mm.

[0021] The third aspect of the present invention provides a method for preparing pseudo-boehmite, wherein the preparation method is carried out in the reaction system described in the second aspect, and the preparation method comprises:

[0022] (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 8-10;

[0023] (2) subjecting the product of step (1) to an aging reaction to obtain pseudo-boehmite;

[0024] The reaction temperature of the gelling reaction is 50°C-80°C; the ratio of the mass concentration of the sodium aluminate solution to the volume concentration of CO2 in the CO2 gas source is ≤2.

[0025] The fourth aspect of the present invention provides pseudo-boehmite obtained by the preparation method described in the third aspect.

[0026] The fifth aspect of the present invention provides a use of the pseudo-boehmite described in the first aspect or the fourth aspect in the field of catalysts and / or adsorbents.

[0027] Through the above technical solution, the beneficial effects obtained are as follows:

[0028] (1) The pseudo-boehmite provided by the present invention is obtained by adjusting the growth rate of the crystal grains on the crystal plane represented by the 130 peak and the crystal plane represented by the 020 peak to obtain pseudo-boehmite of a specific grain size, and has a high specific surface area and a large pore volume;

[0029] (2) In the present invention, the pseudo-boehmite reaction system provided has a simple equipment structure and a small footprint. The porous baffle is arranged perpendicular to the inlet direction of the CO2 gas source. On the one hand, it can break the bubbles, reduce the bubble size, increase the gas-liquid contact area, and enhance mass transfer; on the other hand, the porous baffle is arranged in the reactor with a height-to-diameter ratio ≥ 3. It can effectively prolong the residence time of CO2 gas in the liquid phase under high gas velocity conditions, increase the gas holdup and effectively improve the CO2 capture rate;

[0030] (3) In the present invention, the preparation method of pseudo-boehmite is prepared by using the above-mentioned pseudo-boehmite reaction system, controlling the reaction temperature and the ratio between the reactants, so that the grains can achieve directional growth. Without adding additional growth regulators, the growth rate of the grains on the 020 crystal plane and the 130 crystal plane is adjusted. On this basis, the primary particles are directional agglomerated to form larger elongated secondary particles, thereby obtaining lightweight pseudo-boehmite with high specific surface area and large pore volume;

[0031] (4) The pseudo-boehmite provided by the present invention can be used in the adsorbent field to efficiently adsorb impurities in liquids and gases; it can also be widely used in the catalyst field, especially as a precursor for hydrogenation catalyst carriers, and its specific grain size can improve the hydrogenation performance of the catalyst, especially the residual oil hydrodesulfurization performance. In addition, it can be used in the catalyst matrix to increase the specific surface area of ​​the catalyst and improve the catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the pseudo-boehmite reaction system.

[0033] Description of Reference Numerals

[0034] 1-Sodium aluminate liquid inlet 2-Reaction chamber 3-CO2 gas source inlet

[0035] 4-conical air chamber 5-porous partition 6-air inlet (only one is marked)

[0036] 7-Detection port 8-Exhaust port 9-Discharge port

[0037] 10- Jacket DETAILED DESCRIPTION

[0038] 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.

[0039] A first aspect of the present invention provides a pseudo-boehmite, wherein the R value of the pseudo-boehmite satisfies 1.3≤R≤1.6, wherein R=D(130) / D(020), the D(130) represents the grain size of the crystal plane represented by the 130 peak in the XRD spectrum of the pseudo-boehmite grains, and the D(020) represents the grain size of the crystal plane represented by the 020 peak in the XRD spectrum of the pseudo-boehmite grains, the 130 peak refers to the peak with 2θ of 34-43° in the XRD spectrum, and the 020 peak refers to the peak with 2θ of 10-15° in the XRD spectrum;

[0040] The pore volume of the pseudo-boehmite is 0.6-0.9 mL / g;

[0041] The specific surface area of ​​the pseudo-boehmite is ≥420m 2 / g.

[0042] In the present invention, the pseudo-boehmite limits the growth rate of the grains on the crystal plane represented by the 130 peak and the crystal plane represented by the 020 peak, thereby obtaining pseudo-boehmite of a specific grain size, which has a high specific surface area and a large pore volume.

[0043] According to the present invention, preferably, the R value of the pseudo-boehmite satisfies 1.3≤R≤1.6, such as 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, or any range between the two, 1.4≤R≤1.6. In the present invention, the pseudo-boehmite satisfying the above preferred R value range has a higher specific surface area and a larger pore volume.

[0044] According to the present invention, preferably, the relative crystallinity of the pseudo-boehmite is 75-98%, preferably 80-95%.

[0045] 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: (where D is the grain, K = 1.075, λ is the wavelength of the anode radiation Kα1 spectrum line, β1 is the half-peak width of the corrected diffraction peak, and θ is the Bragg diffraction angle of the diffraction peak). The grain size of (020) is calculated as D(020) with 2θ as the peak parameter of 10-15°, and the grain size of (130) is calculated as D(130) with 2θ as the peak parameter of 34-43°, and R = D(130) / D(020) is calculated.

[0046] In the present invention, the ranges of the values ​​of D(130) and D(020) are not particularly limited, but preferably D(130) is 4-5 nm, and D(020) is 2.5-3.5 nm.

[0047] 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.

[0048] According to the present invention, preferably, the pore volume of the pseudo-boehmite is 0.6-0.9 mL / g, for example, 0.6 mL / g, 0.65 mL / g, 0.7 mL / g, 0.75 mL / g, 0.8 mL / g, 0.85 mL / g, 0.9 mL / g, or any range therebetween, preferably 0.65-0.85 mL / g.

[0049] According to the present invention, preferably, the specific surface area of ​​the pseudo-boehmite is 420-460m 2 / g, for example 420m 2 / g, 425m 2 / g, 430m 2 / g, 435m 2 / g, 440m 2 / g, 445m 2 / g, 450m 2 / g, 455m 2 / g, 460m 2 / g, or any range between them.

[0050] In the present invention, the specific surface area and pore volume of the pseudo-boehmite are determined by the BET method using an ASAP 2405N V1.01 automatic adsorption instrument from Micromeritics, USA, and a low temperature static nitrogen adsorption capacity method. The sample is heated to 1.33×10 -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.

[0051] A second aspect of the present invention provides a pseudo-boehmite reaction system, wherein the reaction system comprises:

[0052] A column reactor is used to contact the sodium aluminate solution with a CO2 gas source to perform a gelling reaction;

[0053] The height-to-diameter ratio of the reactor is ≥3;

[0054] At least one porous partition is provided inside the reactor;

[0055] The porous partition is also provided with at least one air inlet hole;

[0056] The diameter of the air inlet holes of the porous partition is independently 3-10 mm.

[0057] In the present invention, the pseudo-boehmite reaction system has a simple equipment structure and a small footprint. The porous baffles can, on the one hand, break 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 increase CO2 capture rate. 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.

[0058] 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.

[0059] According to the present invention, the cone angle of the conical air chamber is not particularly limited, as long as it can achieve the purpose of the present invention. Preferably, the cone angle of the conical air chamber is 50-70°.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] According to the present invention, the air inlet holes are evenly distributed on the porous baffles, and the number of air inlet holes on each porous baffle is not particularly limited, and can be calculated by those skilled in the art 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.

[0065] According to the present invention, preferably, the geometric center distance 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 distance refers to the straight-line distance between the geometric center positions of the corresponding air inlets. Preferably, the geometric center distance between any two adjacent air inlets is not greater than 5 times their maximum diameters.

[0066] 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.

[0067] 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.

[0068] In the present invention, the reaction system further comprises a jacket, which has heating and heat preservation functions to provide the temperature required by the reaction system. In the present invention, heating or non-heating can be selected according to actual needs.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] The third aspect of the present invention provides a method for preparing pseudo-boehmite, wherein the preparation method is carried out in the reaction system described in the second aspect, and the preparation method comprises:

[0075] (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 8-10;

[0076] (2) subjecting the product of step (1) to an aging reaction to obtain pseudo-boehmite;

[0077] The reaction temperature of the gelling reaction is 50-80°C; the ratio of the mass concentration of the sodium aluminate solution to the volume concentration of CO2 in the CO2 gas source is ≤2.

[0078] In the present invention, the preparation method of the pseudo-boehmite adopts the above-mentioned pseudo-boehmite reaction system for preparation, controls the reaction temperature and the ratio between the reactants, so that the grains can achieve directional growth. Without adding an additional growth regulator, the growth rate of the grains on the 020 crystal plane and the 130 crystal plane is adjusted. On this basis, the primary particles are directional agglomerated to form larger elongated secondary particles, and lightweight boehmite with high specific surface area and large pore volume is obtained.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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%.

[0083] 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.

[0084] 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 lightweight pseudo-boehmite can be prepared under the condition of low CO2 gas concentration, and the CO2 capture rate is not less than 50%.

[0085] 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 10-40 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.

[0086] According to the present invention, preferably, the ratio of the mass concentration of the sodium aluminate solution to the volume concentration of CO2 in the CO2 gas source is ≤ 2, preferably 0.5-2. In the present invention, the reaction system meeting the above definition can reduce side reactions and reduce the content of gibbsite impurity crystals under the reaction system and preparation method.

[0087] According to the present invention, the conditions of the gelling reaction include: the reaction temperature is 50-80°C, such as 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any range between the two, preferably 60-75°C. In the present invention, the gelling reaction under the above conditions is helpful to adjust the growth rate of the grains on the 020 crystal plane and the 130 crystal plane, realize the directional growth of the pseudo-boehmite grains, and obtain lightweight pseudo-boehmite with high specific surface area and high pore volume. The above temperature can be achieved by a hot sodium aluminate solution, a hot CO2 gas source, or a reaction system.

[0088] 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 8-10. 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.

[0089] In the present invention, the pH value of the gelling reaction solution is the pH value of the solution at the gelling reaction temperature. The higher the gelling reaction temperature, the greater the degree of water ionization, and the pH value of the gelling reaction solution is smaller than the pH value of the solution at room temperature.

[0090] According to the present invention, as long as the purpose of the present invention can be achieved, the conditions of the aging reaction are not particularly limited. In some embodiments, the conditions of the aging reaction include: a temperature of 60-100°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any range therebetween, preferably 80-100°C; an aging time of 30-240 minutes, such as 30 minutes, 45 minutes, 60 minutes, 75 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 210 minutes, 240 minutes, or any range therebetween, preferably 60-180 minutes.

[0091] In the present invention, the device for performing the aging reaction is not particularly limited, as long as it can achieve the purpose of the present invention, and can be performed in a separate aging device or in the reaction system. According to a preferred embodiment of the present invention, the aging reaction is performed in a separate aging device.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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%.

[0097] In the present invention, the CO2 capture rate is calculated by the following formula:

[0098]

[0099] 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. The reaction temperature is reached and maintained through the jacket 10. When the pH is 8-10, 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 aged slurry is filtered, washed and dried to obtain pseudo-boehmite dry powder.

[0100] The fourth aspect of the present invention provides pseudo-boehmite obtained by the preparation method described in the third aspect.

[0101] The fifth aspect of the present invention provides a use of the pseudo-boehmite described in the first aspect or the fourth aspect in the field of catalysts and / or adsorbents.

[0102] The pseudo-boehmite provided by the present invention has a high specific surface area and a large pore volume, and can be used in the field of adsorbents to efficiently adsorb impurities in liquids and gases; it can also be widely used in the field of catalysts, especially as a precursor for hydrogenation catalyst carriers, and its specific grain size can improve the hydrogenation performance of the catalyst, especially the residual oil hydrodesulfurization performance. In addition, it can be used in catalyst matrix to increase the specific surface area of ​​the catalyst and improve the catalytic efficiency.

[0103] 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;

[0104] The crystallinity and grain size, specific surface area and pore volume test methods of pseudo-boehmite, the trihydrate impurity content, and the calculation method of CO2 capture rate are described in the above description and will not be repeated here.

[0105] Example 1

[0106] like Figure 1As 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.

[0107] A sodium aluminate solution with a mass concentration of 10 g / L (in terms of Al2O3) is added to the reaction chamber 2 through the sodium aluminate inlet 1, hot water is introduced into the jacket to make the solution temperature reach 60°C, a CO2 gas source (CO2 volume concentration is 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 CO2 gas source has an apparent gas velocity of 1.6 cm / s, the CO2 gas source breaks the bubbles through the inlet holes 6 on the porous partition 5, and reacts with the sodium aluminate solution to form a gel, the pH of the solution in the reaction chamber 2 is monitored through the detection port 7, the temperature of the reaction system is maintained through the jacket 10, and when the pH is 9.8, the introduction of the CO2 gas source is stopped, and 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 aging temperature is controlled at 80°C, and the aging time is 120 minutes. After aging, the slurry was filtered and washed, and the filter cake was dried at 100° C. for 3 hours to obtain pseudo-boehmite powder A1, whose physicochemical properties are shown in Table 1.

[0108] Example 2

[0109] use Figure 1 A reaction system is provided, wherein a sodium aluminate solution with a concentration of 15 g / L (in terms of Al2O3) is added to a reaction chamber 2 through a sodium aluminate inlet 1, hot water is introduced into the jacket to make the solution temperature reach 80°C, a CO2 gas source (CO2 volume concentration is 10%, the remainder is nitrogen) enters the reaction chamber 2 through a CO2 gas source inlet 3 and a conical gas chamber 4 in turn, the CO2 gas source has an apparent gas velocity of 2.2 cm / s, and the CO2 gas source breaks bubbles through an inlet hole 6 on a porous partition 5, and reacts with the sodium aluminate solution to form a gel, the pH of the solution in the reaction chamber 2 is monitored through a detection port 7, the temperature of the reaction system is maintained through a jacket 10, and when the pH is 9.2, the introduction of the CO2 gas source is stopped. The unreacted CO2 gas source is discharged through an exhaust port 8. The slurry after the reaction was transferred to the aging kettle through the discharge port 9 for aging. The aging temperature was controlled at 90°C and the aging time was 180 minutes. The slurry after the aging reaction was filtered and washed. The filter cake was dried at 100°C for 3 hours to obtain pseudo-boehmite powder A2. Its physicochemical properties are shown in Table 1.

[0110] Example 3

[0111] use Figure 1A reaction system is provided, wherein a sodium aluminate solution with a mass concentration of 30 g / L (in terms of Al2O3) is added to a reaction chamber 2 through a sodium aluminate inlet 1, hot water is introduced into the jacket to make the solution temperature reach 65°C, a CO2 gas source (CO2 volume concentration is 15%, and the rest is nitrogen) enters the reaction chamber 2 through a CO2 gas source inlet 3 and a conical gas chamber 4 in turn, and the CO2 gas source has an apparent gas velocity of 2 cm / s. The CO2 gas source breaks bubbles through an inlet hole 6 on a porous partition 5, and reacts with the sodium aluminate solution to form a gel, and the pH of the solution in the reaction chamber 2 is monitored through a detection port 7, and the temperature of the reaction system is maintained through a jacket 10. When the pH is 8.7, the introduction of the CO2 gas source is stopped. The unreacted CO2 gas source is discharged through an exhaust port 8. The slurry after the reaction was transferred to the aging kettle through the discharge port 9 for aging. The aging temperature was controlled at 90°C and the aging time was 120 minutes. The slurry after the aging reaction was filtered and washed. The filter cake was dried at 100°C for 3 hours to obtain pseudo-boehmite powder A3, whose physical and chemical properties are shown in Table 1.

[0112] Example 4

[0113] use Figure 1 A reaction system is provided, wherein a sodium aluminate solution with a mass concentration of 35 g / L (in terms of Al2O3) is added to a reaction chamber 2 through a sodium aluminate inlet 1, hot water is introduced into the jacket to make the solution temperature reach 75°C, a CO2 gas source (CO2 volume concentration is 20%, the remainder is nitrogen) enters the reaction chamber 2 through a CO2 gas source inlet 3 and a conical gas chamber 4 in turn, the CO2 gas source superficial gas velocity is 1.8 cm / s, the CO2 gas source breaks bubbles through an inlet hole 6 on a porous partition 5, and reacts with the sodium aluminate solution to form a gel, the pH of the solution in the reaction chamber 2 is monitored through a detection port 7, the temperature of the reaction system is maintained through a jacket 10, and when the pH is 8.3, the introduction of the CO2 gas source is stopped. The unreacted CO2 gas source is discharged through an exhaust port 8. The slurry after the reaction was transferred to the aging kettle through the discharge port 9 for aging. The aging temperature was controlled at 100°C and the aging time was 120 minutes. The slurry after the aging reaction was filtered and washed. The filter cake was dried at 100°C for 3 hours to obtain pseudo-boehmite powder A4, whose physicochemical properties are shown in Table 1.

[0114] Example 5

[0115] Pseudo-boehmite was prepared according to the method of Example 3, except that two porous baffles were set in the column reactor (one was still at the place where the top of the conical gas chamber was connected to the reaction chamber, and the other was set at a height-to-diameter ratio of 3 places away 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.

[0116] Example 6

[0117] Pseudo-boehmite was prepared according to the method of Example 3, except that the superficial gas velocity of the CO2 gas source was 4 cm / s, to obtain pseudo-boehmite A6, the physicochemical properties of which are shown in Table 1.

[0118] Comparative Example 1

[0119] 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.

[0120] Comparative Example 2

[0121] 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.

[0122] Comparative Example 3

[0123] Pseudo-boehmite was prepared according to the method of Example 3, except that the temperature of the sodium aluminate solution was 90° C. to obtain pseudo-boehmite D3, the physicochemical properties of which are shown in Table 1.

[0124] Comparative Example 4

[0125] Pseudo-boehmite was prepared according to the method of Example 3, except that the temperature of the sodium aluminate solution was 40° C., to obtain pseudo-boehmite D4, the physicochemical properties of which are shown in Table 1.

[0126] Comparative Example 5

[0127] Pseudo-boehmite was prepared according to the method of Example 3, except that the concentration of the sodium aluminate solution was 40 g / L (in terms of Al2O3), to obtain pseudo-boehmite D5, the physicochemical properties of which are shown in Table 1.

[0128] Table 1

[0129]

[0130] 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 lightweight pseudo-boehmite has a higher specific surface area and a larger pore volume, and the CO2 capture rate is not less than 50%.

[0131] 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 R value of the pseudo-boehmite satisfies 1.3≤R≤1.6, wherein R=D(130) / D(020), the D(130) represents the grain size of the crystal plane represented by the 130 peak in the XRD spectrum of the pseudo-boehmite grains, and the D(020) represents the grain size of the crystal plane represented by the 020 peak in the XRD spectrum of the pseudo-boehmite grains, the 130 peak refers to the peak with 2θ of 34-43° in the XRD spectrum, and the 020 peak refers to the peak with 2θ of 10-15° in the XRD spectrum; The pore volume of the pseudo-boehmite is 0.6-0.9 mL / g; The specific surface area of ​​the pseudo-boehmite is ≥420m 2 / g.

2. The pseudo-boehmite according to claim 1, wherein: The pore volume of the pseudo-boehmite is 0.65-0.85 mL / g; Preferably, the specific surface area of ​​the pseudo-boehmite is 420-460m 2 / g; Preferably, the R value of the pseudo-boehmite satisfies 1.4≤R≤1.6; Preferably, the relative crystallinity of the pseudo-boehmite is 75-98%, preferably 80-95%.

3. A pseudo-boehmite reaction system, characterized in that: 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 porous partition is also provided with at least one air inlet hole; The diameter of the air inlet holes of the porous partition is independently 3-10 mm.

4. The reaction system according to claim 3, 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.

5. The reaction system according to claim 3 or 4, 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.

6. The reaction system according to any one of claims 3 to 5, wherein: The number of the air inlet holes is ≥2; Preferably, the apertures of the air inlet holes of the porous partition are independently 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.

7. A method for preparing pseudo-boehmite, characterized in that: The preparation method is carried out in the reaction system described in any one of claims 3 to 6, and 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 8-10; (2) subjecting the product of step (1) to an aging reaction to obtain pseudo-boehmite; The reaction temperature of the gelling reaction is 50-80°C; the ratio of the mass concentration of the sodium aluminate solution to the volume concentration of CO2 in the CO2 gas source is ≤2.

8. The preparation method according to claim 7, 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; Preferably, the mass concentration of the sodium aluminate solution is 5-40 g / L, preferably 10-40 g / L, calculated as Al2O3; Preferably, the ratio of the mass concentration of the sodium aluminate solution to the volume concentration of CO2 in the CO2 gas source is 0.5-2.

9. The preparation method according to claim 7 or 8, wherein: The conditions of the gelling reaction include: the reaction temperature is 60-75°C; Preferably, the conditions of the aging reaction include: a temperature of 60-100° C., preferably 80-100° C.; an aging time of 30-240 minutes, preferably 60-180 minutes; Preferably, 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 7 to 9.

11. Use of the pseudo-boehmite according to any one of claims 1 to 2 and 10 in the field of catalysts and / or adsorbents.

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