CN112744848B - Production process of aluminum sol and aluminum sol prepared by production process - Google Patents
Production process of aluminum sol and aluminum sol prepared by production process Download PDFInfo
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- CN112744848B CN112744848B CN201911053407.XA CN201911053407A CN112744848B CN 112744848 B CN112744848 B CN 112744848B CN 201911053407 A CN201911053407 A CN 201911053407A CN 112744848 B CN112744848 B CN 112744848B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/0004—Preparation of sols
- B01J13/0043—Preparation of sols containing elemental metal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
Abstract
The invention relates to the field of aluminum sol production, and discloses an aluminum sol production process and an aluminum sol prepared by the production process, wherein the process comprises the following steps: contacting a first aluminum source with a first alkali source to obtain a first reaction solution with the pH value of 3-5, then carrying out primary heating and aging, contacting the solution subjected to primary heating and aging, a second aluminum source with a second alkali source to obtain a second reaction solution with the pH value of 3-4.5, then carrying out secondary heating and aging, and carrying out common electrodialysis on the obtained salt-containing aluminum sol to obtain aluminum sol and recovered salt; performing bipolar membrane electrodialysis on the recovered salt to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2); the first temperature-rising aging and the second temperature-rising aging are carried out at a temperature of not more than 100 ℃. The production process provided by the invention has low production cost, can reduce the subsequent concentration pressure, has mild conditions in the whole production process, basically does not generate waste emissions, and can prepare the aluminum sol product with good quality.
Description
Technical Field
The invention relates to the field of preparation of aluminum sol, in particular to a production process of aluminum sol and the aluminum sol prepared by the production process.
Background
The alumina sol is a colloidal solution in which positively charged fine particles of hydrated alumina are uniformly dispersed in water. Currently, aluminum sols are widely used in industry as catalyst binders and water treatment flocculants. The nomenclature of the aluminium sols varies according to the field of application, for example: when used in a catalyst binder, is commonly referred to as an alumina sol; when used in a flocculant, the flocculant is referred to as polyaluminum chloride or aluminum chlorohydrate, but the structural formula of the flocculant can be expressed as follows: [ Al ] 2 (OH) n Cl 6-n ·xH 2 O] m (n＝1-5，m>0)。
The properties of the aluminum sol can be generally expressed by the aluminum content, and the aluminum-chlorine ratio (i.e., the ratio of aluminum element to chlorine element, either by weight or by mole), or the degree of base, which is the molar ratio of hydroxide to aluminum in the polyaluminum chloride.
The preparation method of the aluminum sol is various, and the common preparation method mainly comprises the following steps: the metal aluminum method, the organic alkoxide hydrolysis method, the electrolysis method, the inorganic salt raw material method, the powder dispersion method and the like, wherein the metal aluminum method for preparing aluminum sol by using metal aluminum and hydrochloric acid is still the main production method.
US4028216a firstly introduces a detailed preparation method of metal aluminum sol, which has a simple process flow and is easy to operate, but since the method is to prepare aluminum sol by electrolysis of aluminum hydroxide, the production cost is too high, a large amount of electric energy is consumed, meanwhile, hydrogen generated in the preparation process also brings a potential safety hazard, and the used hydrochloric acid corrodes equipment.
The organic alkoxide hydrolysis method can prepare sol with high purity, large specific surface and uniform particle size distribution. The method is suitable for preparing the alumina powder with high purity requirement. However, the greatest difficulty in the preparation process of the method is that the raw materials are sensitive to water, the hydrolysis reaction is very rapid, precipitates are easy to form, and the raw materials are expensive, flammable, toxic, difficult to store and bring difficulty to industrialization.
CN1177653A reports that the aluminum sol is prepared by adopting an electrolytic method, the polyaluminium chloride is synthesized by an electrochemical method with low voltage and large current, and a common anionic membrane with low price is adopted, so that the preparation cost of the product is reduced, and the method is relatively environment-friendly. However, the electrolytic water consumption is excessive, the initial cost is high (electrodes are needed in the repeating unit), chlorine gas may be generated, and potential safety hazards exist.
The inorganic salt raw material method has the advantages of low price of raw materials, simple method, reduction of the production cost of the aluminum sol, and lower purity of the sol.
The alumina sol prepared by the powder dispersion method omits a hydrolysis step, the process is simple, and the raw materials are industrial products, so that the price is low, the storage is convenient, and the industrialization is easy to realize. However, the raw materials often contain impurities, and the purity of the prepared aluminum sol is relatively low.
Nowadays, the requirements for environmental protection in industrial development and production processes are becoming more and more strict, and the atom economy of the reaction process is being emphasized more and more, so that it becomes more and more important to seek a new low-cost and efficient alumina sol production process.
Disclosure of Invention
The invention aims to provide an aluminum sol production process and an aluminum sol prepared by the production process, the process has low production cost and mild conditions in the whole production process, basically does not generate waste emissions, and the prepared aluminum sol product has good quality and is formed by Al 13 Mainly comprises the following steps.
In order to achieve the above object, a first aspect of the present invention provides a process for producing an aluminum sol, the process comprising:
(1) Carrying out first contact on a first aluminum source and a first alkali source to obtain a first reaction solution, wherein the pH of the first reaction solution is 3-5;
(2) Carrying out second contact on the first reaction liquid, a second aluminum source and a second alkali source to obtain a second reaction liquid, wherein the pH value of the second reaction liquid is 3-4.5;
(3) Carrying out second ageing on the second reaction solution to obtain salt-containing aluminum sol, wherein the second ageing is carried out at the temperature of not more than 100 ℃;
(4) Carrying out common electrodialysis on the salt-containing aluminum sol to obtain aluminum sol and recovered salt;
(5) And (3) performing bipolar membrane electrodialysis on the recovered salt to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2).
The second aspect of the invention provides an aluminum sol prepared by the production process, wherein Al element in the aluminum sol is mainly Al 13 In the form of a sol, which is substantially free of monomeric aluminum.
The aluminum sol production process and the aluminum sol prepared by the production process have the following advantages:
(1) The production process provided by the invention is environment-friendly in the whole production process, basically does not generate waste, and is mild in condition, short in reaction period and low in reaction temperature in the whole production process;
(2) The production process provided by the invention has the advantages that the raw materials adopted are low in price, the utilization rate of the raw materials is high, and further the production cost is low;
(3) The aluminum sol prepared by the production process provided by the invention has high purity, low impurity content, good quality and higher aluminum-chlorine ratio;
(4) The Al element in the alumina sol prepared by the production process provided by the invention is mainly Al 13 In the form of a sol which is substantially free from monomeric aluminum, al 13 The existence of the aluminum sol enables the aluminum sol to have better cohesiveness, and when the aluminum sol is used in a catalyst, the pore volume of the catalyst can be well reserved, and the phenomenon of pore blocking when the traditional aluminum sol is used in the catalyst is overcome;
(5) The alumina sol synthesized by the production process provided by the invention has higher alumina content, and the subsequent concentration pressure is reduced.
Drawings
FIG. 1 shows an alumina sol S1 prepared in example 1 of the present invention 27 Al NMR spectrum.
FIG. 2 shows an alumina sol D1 prepared in comparative example 1 of the present invention 27 Al NMR spectrum.
Fig. 3 is a view for explaining a preferred embodiment of a general electrodialysis involved in the production process of an alumina sol according to the present invention.
Fig. 4 is a diagram for explaining a preferred embodiment of bipolar membrane electrodialysis involved in the production process of an alumina sol according to the present invention.
Description of the reference numerals
1: cation exchange membrane 2: anion exchange membranes
3: bipolar membrane 101: cathode electrode
102: anode 103: cathode chamber
104: anode chamber 105: desalination chamber
106: the concentration chamber 201: cathode electrode
202: anode 203: cathode chamber
204: anode chamber 205: salt chamber
206: acid chamber 207: alkali chamber
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a production process of an aluminum sol, which comprises the following steps:
(1) Carrying out first contact on a first aluminum source and a first alkali source to obtain a first reaction solution, wherein the pH of the first reaction solution is 3-5;
(2) Carrying out second contact on the first reaction liquid, a second aluminum source and a second alkali source to obtain a second reaction liquid, wherein the pH value of the second reaction liquid is 3-4.5;
(3) Carrying out second ageing on the second reaction solution to obtain salt-containing aluminum sol, wherein the second ageing is carried out at the temperature of not more than 100 ℃;
(4) Carrying out common electrodialysis on the salt-containing aluminum sol to obtain aluminum sol and recovered salt;
(5) And (3) performing bipolar membrane electrodialysis on the recovered salt to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2).
According to the present invention, the first aluminum source and the second aluminum source may be the same or different, and preferably, each of the first aluminum source and the second aluminum source is independently at least one selected from the group consisting of an aluminum salt, polyaluminum chloride, and aluminum isopropoxide. Further preferably, the aluminum salt is at least one selected from the group consisting of aluminum chloride, aluminum nitrate and aluminum sulfate. The polyaluminum chloride can be commercial polyaluminum chloride.
According to a preferred embodiment of the invention, the first aluminium source is aluminium chloride. Specifically, the first aluminum source may be used in the form of a solution. Specifically, the concentration of the first aluminum source may be 1 to 32 wt%.
According to a preferred embodiment of the present invention, the second aluminum source is at least one selected from the group consisting of aluminum chloride, polyaluminum chloride and aluminum isopropoxide, preferably polyaluminum chloride.
In the research process, the inventor of the present invention finds that when the first aluminum source is aluminum chloride and the second aluminum source is polyaluminum chloride, it is more beneficial to reduce the subsequent concentration pressure.
The terms "first" and "second" are not used in any limiting sense, but are used to distinguish between operations performed at different stages or between materials added at different stages.
In the present invention, the first alkali source and the second alkali source may be the same or different, and the alkali may be an alkali substance sufficient to convert the aluminum source into the aluminum sol. Preferably, the first and second alkali sources are each independently selected from the group consisting of alkali metal hydroxide, NH 3 ·H 2 O and an organic base. Specific examples of the alkali metal hydroxide may include, but are not limited to, naOH and/or KOH. Specific examples of the organic base may include, but are not limited to, at least one of n-butylamine, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.
The first and second sources of base are typically provided in the form of aqueous solutions. The concentration of the first and second alkalinity sources in the aqueous solution may be selected according to the type of alkalinity source, for example: for aqueous ammonia, the concentration may be 1 to 25% by weight, preferably 2 to 20% by weight; for alkali metal hydroxides, the concentration may be from 5 to 20% by weight, preferably from 12 to 18% by weight; for the organic base, the concentration thereof may be 3 to 20% by weight, preferably 5 to 15% by weight.
The amounts of the first alkali source and the second alkali source can be selected according to the amounts of the first aluminum source and the second aluminum source. Preferably, the mass ratio of the total amount of the first alkali source and the second alkali source to the total amount of the first aluminum source and the second aluminum source is (0.2-1.5): 1, preferably (0.3-1): 1, more preferably (0.39-0.6): 1, the first and second alkali sources are substituted with OH - And/or N, wherein the first aluminum source and the second aluminum source are calculated by aluminum element. When the alkali source contains OH - Or N, the amount of the alkali source is OH - Or N is counted; when the alkali source contains OH - When N is used, the amount of the alkali source is OH - And (6) counting. For example, tetrapropylammonium hydroxide is used in an amount of OH - And (6) counting.
According to a preferred embodiment of the present invention, the mass ratio of the first aluminum source to the second aluminum source is (0.1-2): 1, preferably (0.3-1.5): 1, more preferably (0.5-1): 1, more preferably (0.59-0.73): 1.
according to the production process provided by the present invention, the first aluminum source and the first alkali source in step (1) may be subjected to the first contact under conventional conditions, for example, normal temperature (25 ℃) and normal pressure. Typically, the duration of the first contact is sufficient to convert the first source of aluminum to a salt-containing aluminum sol and is based on a pH of 3 to 5, typically the duration of the first contact may be 1 to 24 hours, preferably 2 to 18 hours. From the viewpoint of further improving the uniformity of the contact reaction, the first contact is preferably carried out under conditions accompanied by stirring.
According to a preferred embodiment of the present invention, the pH of the first reaction solution is 3 to 5, more preferably 3 to 4.5, and still more preferably 3.3 to 4.5.
According to the present invention, preferably, the process further comprises: and (2) carrying out first aging on the first reaction solution in the step (1), and then carrying out the step (2).
According to a preferred embodiment of the present invention, the process for producing an aluminum sol comprises:
(1) Carrying out first contact on a first aluminum source and a first alkali source to obtain a first reaction solution, wherein the pH of the first reaction solution is 3-5; subjecting the first reaction solution to a first aging, the first aging being performed at a temperature of not more than 100 ℃;
(2) Carrying out second contact on the reaction liquid after the first aging in the step (1), a second aluminum source and a second alkali source to obtain a second reaction liquid, wherein the pH value of the second reaction liquid is 3-4.5;
(3) Carrying out second ageing on the second reaction solution to obtain salt-containing aluminum sol, wherein the second ageing is carried out at the temperature of not more than 100 ℃;
(4) Carrying out common electrodialysis on the salt-containing aluminum sol to obtain aluminum sol and recovered salt;
(5) And (3) performing bipolar membrane electrodialysis on the recovered salt to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2).
According to the invention, preferably, the first ageing is carried out at a temperature of between 30 and 95 ℃, preferably between 30 and 70 ℃, more preferably between 35 and 55 ℃.
According to the present invention, it is further preferred that the time of the first aging is 10 to 120min, preferably 20 to 60min.
In the step (2) of the present invention, the first reaction solution obtained in the step (1) is preferably contacted with the second aluminum source and the second alkali source in the second contact with stirring, from the viewpoint of further improving the uniformity of the contact reaction.
According to a preferred embodiment of the present invention, the pH of the second reaction solution is 3 to 4.5, more preferably 3.3 to 4.5, and still more preferably 3.7 to 4.5.
According to the invention, the temperature of the second ageing is preferably at least 10 ℃ higher, preferably between 10 and 35 ℃ higher, and more preferably between 15 and 30 ℃ higher than the temperature of the first ageing.
According to a preferred embodiment of the invention, the second aging is carried out at a temperature of 40 to 95 ℃, preferably 40 to 80 ℃, more preferably 60 to 80 ℃, even more preferably 70 to 80 ℃.
According to a preferred embodiment of the invention, the second aging is carried out for a period of 3 to 10 hours, preferably 4 to 8 hours.
According to the invention, preferably, the first aging and the second aging are each independently carried out under stirring conditions.
The stirring in the above different steps is not particularly limited in the present invention, and may be conventional mechanical stirring or magnetic stirring.
According to the invention, the production process is not limited to only two contacts with an alkali source and aging. Preferably, the above production process provided by the present invention may further comprise repeating the steps (2) and (3), and then performing the steps (4) and (5). Namely, the heated solution obtained in the step (3) is contacted with an aluminum source and an alkali source to obtain a reaction solution with the pH of 3-4.5, and the reaction solution is aged again.
According to the production process of the aluminum sol, in the step (4), common electrodialysis is carried out on the salt-containing aluminum sol to obtain the aluminum sol and the recovered salt, and the aluminum sol is used as an aluminum sol product or is used as the aluminum sol product after partial solvent in the aluminum sol is removed. In the present invention, electrodialysis in which the stack of the electrodialyzer used does not contain bipolar membranes is referred to as general electrodialysis (herein, also simply referred to as electrodialysis), and electrodialysis in which the stack of the electrodialyzer used contains bipolar membranes is referred to as bipolar membrane electrodialysis.
The invention can directly send the salt-containing aluminum sol obtained in the step (3) into the step (4) for common electrodialysis.
And (4) desalting the salt-containing aluminum sol by adopting common electrodialysis to obtain the aluminum sol (desalted aluminum sol) and recycling salt. The electrodialyzer used for the ordinary electrodialysis may be a conventional electrodialyzer capable of carrying out the above-mentioned treatment process.
According to a preferred embodiment of the present invention, the membrane stack of the electrodialyzer used for the general electrodialysis in step (4) has at least one membrane unit. As shown in fig. 3, the membranes in the membrane unit are a cation exchange membrane 1 and an anion exchange membrane 2, and the cation exchange membrane 1 and the anion exchange membrane 2 are arranged at intervals to divide the internal space of the membrane unit into a desalination chamber 105 and a concentration chamber 106. During electrodialysis, the salt-containing aluminum sol enters the desalting chamber 105, water enters the concentrating chamber 106, cations and anions generated by the aluminum salt enter the concentrating chamber through the cation exchange membrane 1 and the anion exchange membrane 2 respectively in the common electrodialysis process, the aluminum sol is retained in the desalting chamber, so that the aluminum sol is obtained from the desalting chamber 105, and the solution of the recovered salt is obtained from the concentrating chamber 106.
Fig. 3 exemplarily shows the configuration of one membrane unit, but it is understood by those skilled in the art that the membrane stack may have a plurality of membrane units shown in fig. 3, for example, it may be generally 1 to 200 membrane units, preferably 2 to 100 membrane units, more preferably 3 to 50 membrane units, further preferably 5 to 30 membrane units, such as 8 to 15 membrane units.
The cation exchange membrane and the anion exchange membrane can be selected conventionally, can be a homogeneous phase ion exchange membrane, can also be a heterogeneous phase ion exchange membrane, and can also be a combination of the homogeneous phase ion exchange membrane and the heterogeneous phase ion exchange membrane. Preferably, the cation exchange membrane and the anion exchange membrane are each homogeneous ion exchange membranes, more preferably are each homogeneous styrene-type ion exchange membranes.
As shown in FIG. 3, in a conventional electrodialyzer, a cation exchange membrane 1 and an anion exchange membrane 2 are arranged at intervals between a cathode 101 and an anode 102. In general, the ion exchange membrane adjacent to the cathode 101 is a cation exchange membrane, and the chamber formed by the cathode 101 and the adjacent cation exchange membrane is a cathode chamber 103; the ion exchange membrane adjacent to the anode 102 is an anion exchange membrane, and the chamber formed by the anode 102 and the adjacent anion exchange membrane is an anode chamber 104. In the case of ordinary electrodialysis, an electrode solution is fed into the cathode chamber 103 and the anode chamber 104.
The polar liquid is an aqueous solution of electrolyte. The electrolyte may be an inorganic electrolyte and/or an organic electrolyte, and specific examples thereof may include, but are not limited to, at least one of ammonium sulfate, sodium nitrate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium nitrate, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium hydroxide, potassium hydroxide, formic acid, acetic acid, sodium formate, potassium formate, and quaternary ammonium type electrolytes. Preferably, the electrolyte is an inorganic electrolyte. More preferably, the electrolyte is sodium sulfate and/or ammonium sulfate. Further preferably, the cation of the electrolyte is the same as the cation of the salt in the salt-containing aluminum sol.
In general electrodialysis, the electrolyte in the electrode solution entering the cathode chamber and the anode chamber may be the same or different in type and content. From the viewpoint of ease of operation, the kinds and contents of electrolytes in the electrode solutions introduced into the cathode chamber and the anode chamber are the same. Generally, the electrolyte content in the polar liquid may be 1 to 15% by weight, preferably 3 to 10% by weight.
In a conventional electrodialysis process, the current density may be in the range of 5 to 1000 amps per square meter, preferably 10 to 500 amps per square meter, more preferably 12 to 200 amps per square meter, even more preferably 15 to 100 amps per square meter, such as 15 to 40 amps per square meter. The magnitude of the current density can be controlled by controlling the magnitude of the voltage applied to the stack.
In the course of research, the inventors of the present invention have found that, in the case of performing general electrodialysis, after a certain period of electrodialysis has been performed, the internal resistance of the electrodialyzer increases, so that normal electrodialysis cannot be performed, and shutdown for maintenance is required. Analysis shows that the reason for increasing the internal resistance of the electrodialyzer is mainly that the surface of the cation exchange membrane close to the cathode, which faces the side of the desalting chamber, is seriously scaled. In view of the above, the inventors of the present invention have conducted intensive studies and found that, in the electrodialysis process, if the electrolyte content in the electrode solution entering the cathode chamber is controlled to 5 to 7 wt%, and the current density is controlled to 20 to 35 amperes per square meter in the electrodialysis process, not only can a high electrodialysis efficiency be maintained, but also the tendency of scaling of the membrane surface on the side of the cation exchange membrane close to the cathode facing the desalination chamber can be effectively suppressed, and the frequency of shutdown maintenance can be reduced. In this case, the content of the electrolyte in the electrode solution introduced into the anode chamber may be controlled to 5 to 7% by weight from the viewpoint of ease of operation.
In a common electrodialysis process, the temperature of the salt-containing aluminium sol entering the desalination chamber may be in the range of 5-35 deg.c, preferably 20-30 deg.c. The content of aluminium in the salt-containing aluminium sol subjected to conventional electrodialysis, expressed as Al, may be 1-30 wt.%, preferably 1.5-15 wt.% 2 O 3 And (6) counting. From the viewpoint of further extending the service life of a conventional electrodialyser while taking operational efficiency into consideration, the content of aluminum in the salt-containing alumina sol subjected to conventional electrodialysis is preferably 2 to 10% by weight, more preferably 4 to 9% by weight.
In the step (4), the number of the conventional electrodialysers may be one or two or more. When the number of the common electrodialysers is more than two, the common electrodialysers may be connected in series, in parallel or in a combination of series and parallel. The series connection means that a plurality of electrodialysers are connected together in an end-to-end mode to form a flow path of fluid, and desalted alumina sol output by the electrodialyser positioned at the upstream then enters the electrodialyser directly connected with the upstream to continue electrodialysis, so that the multistage electrodialysis is realized. The parallel connection means that the salt-containing alumina sol of a plurality of electrodialysers has the same source, and forms a branch flow with the same source but without physical distribution connection, thereby realizing multi-machine parallel treatment and improving the treatment capacity of the device. The series connection and parallel connection combined use means that when a plurality of electrodialysers are combined for use, the parallel connection and the series connection are mixed for use, as an example of the series connection and parallel connection combined use, a plurality of groups of electrodialysers can be arranged, the electrodialysers are connected in parallel between each group, and the electrodialysers are connected in series in each group, so that the multistage electrodialysis can be realized, and higher treatment capacity can be obtained.
The production process of the aluminum sol comprises the following steps (5): and (3) performing bipolar membrane electrodialysis on the recovered salt to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2). And outputting the product acid.
The bipolar membrane electrodialyzer adopted by the bipolar membrane electrodialysis can be a two-compartment bipolar membrane electrodialyzer or a three-compartment bipolar membrane electrodialyzer.
As an example of a two-compartment bipolar membrane electrodialyzer, the membrane units of the membrane stack of the bipolar membrane electrodialyzer contain bipolar membranes and anion exchange membranes arranged at intervals, the compartment between the anion exchange layer and the anion exchange membrane of the bipolar membranes is an alkali compartment, and the compartment between the cation exchange layer and the anion exchange membrane of the bipolar membranes is an acid compartment. In the bipolar membrane electrodialysis, the recovered salt enters the alkali chamber, the water enters the acid chamber, the anion formed by the recovered salt enters the acid chamber through the anion exchange membrane, and the hydrogen ion (H) generated by the water electrolysis of the bipolar membrane + ) Combines to produce a recovered acid, cations formed from the recovered salt in the alkaline compartment, and hydroxide ions (OH) produced by the electrolysis of water using the bipolar membrane - ) Combining to form the recovered base.
As another example of a two-compartment bipolar membrane electrodialyzer, the membrane units of the membrane stack of the bipolar membrane electrodialyzer contain bipolar membranes and cation exchange membranes arranged at intervals, the compartment between the cation exchange layer and the cation exchange membrane of the bipolar membranes is an acid compartment, and the compartment between the anion exchange layer and the cation exchange membrane of the bipolar membranes is an alkali compartment. When bipolar membrane electrodialysis is carried out, recovered salt enters an acid chamber, water enters an alkali chamber, cations formed by the recovered salt enter the alkali chamber through a cation exchange membrane and are combined with hydroxide ions generated by bipolar membrane electrolysis water to form recovered alkali, and anions formed by the recovered salt are combined with hydrogen ions generated by the bipolar membrane electrolysis water in the acid chamber to generate product acid.
In a preferred embodiment, as shown in fig. 4, the membranes in the membrane unit of the membrane stack of the bipolar membrane electrodialyzer are a bipolar membrane 3, an anion exchange membrane 2 and a cation exchange membrane 1, the bipolar membrane 3 is separated by two of the anion exchange membrane 2 and the cation exchange membrane 1, the internal space of the membrane unit is divided into an acid chamber 206, a salt chamber 205 and a base chamber 207, the salt chamber 205 is located between the acid chamber 206 and the base chamber 207, wherein the compartment between the adjacent anion exchange membrane 2 and the cation exchange membrane 1 is the salt chamber 205, the compartment between the cation exchange layer of the bipolar membrane 3 and the anion exchange membrane 2 is the acid chamber 206, and the compartment between the anion exchange layer of the bipolar membrane 3 and the cation exchange membrane 1 is the base chamber 207. During electrodialysis, recovered salt enters the salt chamber 205, water respectively enters the acid chamber 206 and the alkali chamber 207, under the action of an electric field, cations formed by the recovered salt in the salt chamber 205 enter the alkali chamber 207 through the cation exchange membrane 1 and are combined with hydroxide ions formed by water electrolysis of the bipolar membrane 3 to generate recovered alkali; the anions formed by the recovered salt enter the acid chamber 206 through the anion exchange membrane 2 and are combined with the hydrogen ions formed by the water electrolysis of the bipolar membrane 3 to generate recovered acid. The water output from the salt chamber of the bipolar membrane electrodialysis can be recycled as the water inlet of a concentration chamber of the common electrodialysis and a chamber (such as an acid chamber and an alkali chamber of a three-compartment bipolar membrane electrodialysis device) of the bipolar membrane electrodialysis, which takes water as a feed material.
Fig. 4 exemplarily shows the construction of one membrane unit of a three-compartment bipolar membrane electrodialyzer, but it will be understood by those skilled in the art that a membrane stack of a bipolar membrane electrodialyzer may have a plurality of membrane units shown in fig. 4, and may typically be 1 to 200 membrane units, preferably 2 to 100 membrane units, more preferably 3 to 50 membrane units, and further preferably 5 to 30 membrane units, such as 8 to 15 membrane units.
In the step (5), the number of bipolar membrane electrodialysers may be one or two or more. When the number of the bipolar membrane electrodialysers is two or more, the bipolar membrane electrodialysers may be connected in series, may be connected in parallel, or may be a combination of series and parallel connections. The series connection means that a plurality of bipolar membrane electrodialysers are connected together in an end-to-end connection mode to form a fluid flow path, and feed liquid output by a salt chamber of the bipolar membrane electrodialyser positioned at the upstream enters the bipolar membrane electrodialyser directly connected with the downstream to continue the bipolar membrane electrodialysis, so that the multistage bipolar membrane electrodialysis is realized. The parallel connection means that the sources of the recovered salts of a plurality of bipolar membrane electrodialysers are the same, and the bipolar membrane electrodialysers form a branch flow which has no stream communication but has the same source, so that the multi-machine parallel treatment is realized, and the treatment capacity of the device is improved. The series connection and parallel connection combined use means that when a plurality of bipolar membrane electrodialysers are combined for use, parallel connection and series connection are mixed for use, as an example of the series connection and parallel connection combined use, a plurality of groups of bipolar membrane electrodialysers can be arranged, the bipolar membrane electrodialysers are connected in parallel between each group, and the bipolar membrane electrodialysers are connected in series in each group, so that the multistage bipolar membrane electrodialysis can be realized, and higher treatment capacity can be obtained.
In the bipolar membrane electrodialysis process, polar liquid is introduced into a cathode chamber and an anode chamber of the bipolar membrane electrodialysis device. The types of electrolytes in the electrode solutions introduced into the cathode chamber and the anode chamber may be the same or different, and are preferably the same. The electrolyte in the polar liquid may be an inorganic electrolyte and/or an organic electrolyte, and specific examples thereof may include, but are not limited to, one or more of ammonium sulfate, sodium nitrate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium nitrate, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium hydroxide, potassium hydroxide, formic acid, acetic acid, sodium formate, potassium formate, and quaternary ammonium type electrolytes. Preferably, the electrolyte is an inorganic electrolyte. More preferably, the electrolyte is sodium sulfate and/or ammonium sulfate. Further preferably, the cation of the electrolyte is the same as the cation of the recovered salt.
The electrolyte contents in the polar liquids introduced into the cathode compartment and the anode compartment of the bipolar membrane electrodialyzer may be the same or different, preferably the same. Generally, the electrolyte content in the polar liquid may be 1 to 10% by weight, preferably 3 to 8% by weight.
In step (5), the bipolar membrane electrodialysis may be carried out under conditions sufficient to recover the salt-forming product acid and to recover the base. Generally, in the bipolar membrane electrodialysis process, the voltage may be in the range of 5-30V, preferably 8-25V, more preferably 10-20V. In the process of bipolar membrane electrodialysis, the temperature of the solution containing the recovered salt passed into the salt compartment can be in the range of 10-60 deg.C, preferably 15-40 deg.C, more preferably 20-30 deg.C.
According to the production process of the aluminum sol, the recovered alkali obtained by bipolar membrane electrodialysis can be recycled for the step (1) and/or the step (2), so that the production process of the aluminum sol basically has no waste discharge, and green and environment-friendly production is realized. The solution for recovering the alkali obtained by bipolar membrane electrodialysis can be directly circulated, or can be circulated after concentration.
According to the process for producing an aluminum sol of the present invention, the aluminum sol obtained in step (4) has a low salt content (usually, the mass content of the salt in the aluminum sol obtained in step (4) is 200ppm or less), and can be directly output as an aluminum sol product or output as an aluminum sol product after removing a part of the solvent in the aluminum sol.
According to the process for producing an aluminum sol of the present invention, the aluminum sol can be concentrated by removing a part of the solvent from the aluminum sol by a conventional method, for example, the aluminum sol can be partially removed by evaporation at a temperature of 50 to 150 ℃, preferably 70 to 120 ℃, and more preferably 80 to 95 ℃. The amount of the solvent to be removed can be selected according to the specific application of the aluminum sol. Typically, with alumina (i.e., al) 2 O 3 ) The content of aluminum in the aluminum sol product is generally controlled to 10 to 30% by weight, preferably 15 to 25% by weight, and the aluminum sol is particularly suitable as a binder for a catalyst.
According to the second aspect of the invention, the invention also provides the aluminum sol prepared by the production process, wherein in the aluminum sol, al element is mainly Al 13 In the form of a sol which is substantially free of monomeric aluminum. The Al element is mainly Al 13 The formal presence means that 50% or more of the Al element is present as Al 13 The form exists. The aluminum sol does not contain monomer aluminum basically, namely the aluminum element exists in the form of the monomer aluminum and has the content of less than 10 percent.
The Al element can exist in a form of 27 And determining an Al NMR spectrum. In that 27 Al is Al at delta 60-61 in an Al NMR spectrum 13 The characteristic peak of the tetra-coordinated aluminum is that the delta is Al at the position of 10-12 13 And/or Al 30 Delta is a characteristic peak of dimeric aluminum at 2-3, and delta is a characteristic peak of monomeric aluminum at 0. The Al can be determined according to the peak area of the characteristic peak 13 Amount of Al element formally present.
According to a preferred embodiment of the present invention, the aluminum sol has an aluminum to chlorine mass ratio of 1 to 1.6, preferably 1 to 1.4, and more preferably 1 to 1.2.
According to the inventionIn a preferred embodiment, al is used as Al in the alumina sol 2 O 3 The aluminum content is 5 to 30% by weight.
The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.
In the following examples, the content of aluminum in the prepared aluminum sol product was measured by the method specified in RIPP34-90, and the content of chlorine in the prepared aluminum sol product was measured by the ion chromatography method.
The pH of the alumina sol was measured using a pH meter (from Mettler-Toriledo).
And (3) determining the existence form of the Al element in the alumina sol by adopting a nuclear magnetic resonance spectrometer.
Example 1
(1) 515g of ammonia water having a concentration of 15% by weight was slowly added to 900g of an aluminum chloride solution having a concentration of 20% by weight with stirring at ambient temperature (25 ℃ C., the same applies hereinafter) to obtain a first reaction solution having a pH of 3.4 with stirring for 0.5 hour, the temperature of the first reaction solution was raised to 50 ℃ C., and the reaction was stirred at that temperature for 0.5 hour;
(2) Introducing 200g of polyaluminum chloride (Al element content 51.06 g) into the heated solution obtained in step (1) with stirring, and adding 190g of 20 wt% aqueous ammonia to obtain a second reaction solution having a pH of 3.9;
(3) The temperature of the second reaction solution was raised to 80 ℃ and stirred at this temperature for 3 hours, then cooled to ambient temperature to give a concentration of 5.01% by weight (as Al) 2 O 3 Meter) of a salt-containing aluminium sol;
(4) Ordinary electrodialysis: and (3) storing the salt-containing alumina sol obtained in the step (3) in a circulating tank, introducing the salt-containing alumina sol into a desalting chamber of common electrodialysis from the circulating tank, introducing deionized water into a concentrating chamber of the common electrodialyzer, and introducing polar liquid (wherein the electrolyte in the polar liquid is ammonium sulfate, and the content of the electrolyte in the polar liquid is 5 wt%) into a cathode chamber and an anode chamber of the common electrodialyzer to carry out the common electrodialysis. Wherein the membrane stack of the common electrodialyzer has 10 membrane units, and adopts cation exchange membrane and anion exchange membrane (purchased from Beijing Tint Runfan technology development)Limited, membrane stack size 200X 400 mm) is a homogeneous styrene ion exchange membrane, and the current density is controlled to be 35mA/cm in the electrodialysis process 2 At 20 deg.C, communicating the desalting chamber of a common electrodialyzer with a circulation tank, and performing common electrodialysis for 1 hr to obtain desalted alumina sol (made of Al) 2 O 3 9.6% by weight of aluminum and 200ppm or less by mass of salt) and an ammonium chloride solution as a recovered salt;
(5) Bipolar membrane electrodialysis: and (3) feeding the recovered salt ammonium chloride solution obtained in the step (4) into a salt chamber of a bipolar membrane electrodialyzer, simultaneously feeding deionized water into an acid chamber and an alkali chamber of the bipolar membrane electrodialyzer, feeding polar liquid (wherein the electrolyte in the polar liquid is ammonium sulfate, and the content of the electrolyte in the polar liquid is 5 wt%) into a cathode chamber and an anode chamber of the bipolar membrane electrodialyzer, performing bipolar membrane electrodialysis for 0.5 hour, obtaining hydrochloric acid serving as a product acid from the acid chamber, and obtaining ammonia water serving as recovered alkali from the alkali chamber. And (3) outputting hydrochloric acid as a product, concentrating ammonia water to a concentration of 15 wt%, and circularly conveying the concentrated ammonia water to the step (1) and the step (2). Wherein, the membrane stack of the bipolar membrane electrodialyzer has 10 membrane units, the adopted cation exchange membrane, anion exchange membrane and bipolar membrane (purchased from Beijing Tingting Membrane technology development Limited, the size of the membrane stack is 200 x 400 mm) are homogeneous styrene ion exchange membranes, the voltage is constant at 20V in the bipolar membrane electrodialysis process, and the temperature of the recovered ammonium chloride solution sent into the bipolar membrane electrodialyzer is 20 ℃;
(6) Concentrating: stirring the desalted alumina sol obtained in the step (4) at the temperature of 85 ℃ to remove part of water to obtain the solution with the concentration of 21.0 weight percent (based on Al) 2 O 3 Meter) of the aluminum sol product.
Of aluminium sols 27 The NMR spectrum of Al is shown in FIG. 1, and it can be seen from FIG. 1 that Al exists at a delta of 60 to 61 13 The characteristic peak of monomeric aluminum does not exist at a position where delta is 0, and it can be seen that Al element is mainly Al 13 The form exists.
Comparative example 1
50g of an aluminum ingot was put into 400g of concentrated hydrochloric acid (37 wt%) with stirring, and the temperature was raisedKeeping the temperature at 85 ℃ for 7 hours to obtain the concentration of 20.9 weight percent (based on Al) 2 O 3 Meter) of the alumina sol D1, the mass ratio of aluminum to chlorine of the alumina sol D1 is 1. Of the aluminium Sol D1 27 The NMR spectrum of Al is shown in FIG. 2, and it can be seen from FIG. 2 that Al exists at a delta of 60 to 61 13 But the characteristic peak of the four-coordinate aluminum is weaker, the characteristic peak of the monomer aluminum exists at delta of 0, and Al exists at delta of 10-12 13 And/or Al 30 And a peak characteristic of dimeric aluminium is present at δ of 2-3.
Example 2
(1) 660g of a 15 wt% aqueous sodium hydroxide solution was slowly added to 920g of a 20 wt% aqueous aluminum chloride solution at ambient temperature (25 ℃ C., the same applies hereinafter) with stirring to obtain a first reaction solution having a pH of 3.3 with stirring for 1 hour, the temperature of the first reaction solution was raised to 55 ℃ C., and the reaction was stirred at that temperature for 1 hour;
(2) Introducing 200g of polyaluminum chloride (Al element content 51.06 g) into the heated solution obtained in step (1) with stirring, and adding 100g of a 20 wt% sodium hydroxide solution to obtain a second reaction solution having a pH of 3.8;
(3) The temperature of the second reaction solution was raised to 80 ℃ and stirred at that temperature for 4.5 hours, then cooled to ambient temperature to give a concentration of 4.9 wt.% (as Al) 2 O 3 Meter) of a salt-containing aluminium sol;
(4) Ordinary electrodialysis: and (3) storing the salt-containing alumina sol obtained in the step (3) in a circulating tank, introducing the salt-containing alumina sol into a desalting chamber of common electrodialysis from the circulating tank, introducing deionized water into a concentrating chamber of the common electrodialyzer, and introducing polar liquid (wherein the electrolyte in the polar liquid is sodium sulfate, and the content of the electrolyte in the polar liquid is 7 wt%) into a cathode chamber and an anode chamber of the common electrodialyzer to carry out the common electrodialysis. Wherein the membrane stack of the common electrodialyzer has 10 membrane units, the adopted cation exchange membrane and anion exchange membrane (available from Beijing Tingting Membrane technology development Limited, with the size of the membrane stack being 200 × 400 mm) are homogeneous styrene ion exchange membranes, and in the electrodialysis process, the current density is controlled to be 20mA/cm 2 Temperature ofCommunicating the desalting chamber of a common electrodialyzer with a circulation tank at 30 deg.C, and performing common electrodialysis for 1.2 hr to obtain desalted alumina sol (made of Al) 2 O 3 1-2 wt% of aluminum and 200ppm or less of salt by mass) and a sodium chloride solution as a recovered salt;
after the ordinary electrodialyzer runs for 21 hours under the condition, the efficiency is reduced, the shutdown maintenance finds that the surface of the cation exchange membrane adjacent to the cathode is scaled, and after the cation exchange membrane adjacent to the cathode is replaced, the electrodialyzer returns to normal operation;
(5) Bipolar membrane electrodialysis: and (3) feeding the recovered salt sodium chloride solution obtained in the step (4) into a salt chamber of a bipolar membrane electrodialyzer, simultaneously feeding deionized water into an acid chamber and an alkali chamber of the bipolar membrane electrodialyzer, feeding polar liquid (wherein the electrolyte in the polar liquid is sodium sulfate, and the content of the electrolyte in the polar liquid is 5 wt%) into a cathode chamber and an anode chamber of the bipolar membrane electrodialyzer, performing bipolar membrane electrodialysis for 0.5 hour, obtaining hydrochloric acid serving as a product acid from the acid chamber, and obtaining a sodium hydroxide solution serving as recovered alkali from the alkali chamber. And (3) outputting hydrochloric acid as a product, concentrating the sodium hydroxide aqueous solution to a concentration of 15 wt%, and circularly conveying the concentrated sodium hydroxide aqueous solution to the step (1) and the step (2). Wherein, the membrane stack of the common electrodialysis has 10 membrane units, the adopted cation exchange membrane, anion exchange membrane and bipolar membrane (purchased from Beijing Tingting technology development Limited company, the size of the membrane stack is 200 multiplied by 400 mm) are homogeneous styrene ion exchange membranes, the voltage is constant at 20V in the bipolar membrane electrodialysis process, and the temperature of the recovered sodium chloride solution sent into the bipolar membrane electrodialyzer is 20 ℃;
(6) Concentrating: stirring the desalted alumina sol obtained in the step (4) at the temperature of 85 ℃ to remove part of water to obtain the concentration of 19.8 weight percent (based on Al) 2 O 3 Meter) of the aluminum sol product.
Of products based on aluminium sols 27 The NMR spectrum of Al is similar to that of FIG. 1, with Al present at delta 60-61 13 The characteristic peak of monomeric aluminum does not exist at a position where delta is 0, and it can be seen that Al element is mainly Al 13 The form exists.
Example 3
(1) 515g of ammonia water having a concentration of 15% by weight was slowly added to 900g of an aluminum chloride solution having a concentration of 20% by weight with stirring at ambient temperature (25 ℃ C., the same applies hereinafter) to obtain a first reaction solution having a pH of 3.4 with stirring for 0.5 hour, the temperature of the first reaction solution was raised to 50 ℃ C., and the reaction was stirred at that temperature for 0.5 hour;
(2) Introducing 200g of polyaluminum chloride (Al element content: 51.06 g) into the heated solution obtained in step (1) with stirring, and adding 352g of a 15% by weight n-butylamine solution to obtain a second reaction solution having a pH of 4.1;
(3) The temperature of the second reaction solution was raised to 80 ℃ and stirred at this temperature for 4 hours, then cooled to ambient temperature to give a concentration of 4.7% by weight (as Al) 2 O 3 Meter) of a salt-containing aluminium sol;
(4) Common electrodialysis: and (3) storing the salt-containing alumina sol obtained in the step (3) in a circulating tank, introducing the salt-containing alumina sol into a desalting chamber of common electrodialysis from the circulating tank, introducing deionized water into a concentrating chamber of the common electrodialyzer, and introducing polar liquid (wherein the electrolyte in the polar liquid is ammonium sulfate, and the content of the electrolyte in the polar liquid is 5 wt%) into a cathode chamber and an anode chamber of the common electrodialyzer to carry out the common electrodialysis. Wherein the membrane stack of the common electrodialyzer has 10 membrane units, the adopted cation exchange membrane and anion exchange membrane (purchased from Beijing Tint Runfei technology development Limited, with the size of the membrane stack being 200 × 400 mm) are homogeneous styrene ion exchange membranes, and in the electrodialysis process, the current density is controlled to be 35mA/cm 2 At 20 deg.C, communicating the desalting chamber of a common electrodialyzer with a circulation tank, and performing common electrodialysis for 1 hr to obtain desalted alumina sol (made of Al) 2 O 3 1-2% by weight of aluminum and 200ppm or less by mass of salt) and an ammonium chloride solution as a recovered salt.
(5) Bipolar membrane electrodialysis: and (3) feeding the recovered ammonium chloride solution obtained in the step (4) into a salt chamber of a bipolar membrane electrodialyzer, simultaneously feeding deionized water into an acid chamber and an alkali chamber of the bipolar membrane electrodialyzer, feeding polar liquid (wherein the electrolyte in the polar liquid is ammonium sulfate, and the content of the electrolyte in the polar liquid is 5 wt%) into a cathode chamber and an anode chamber of the bipolar membrane electrodialyzer, performing bipolar membrane electrodialysis for 0.5 hour, obtaining hydrochloric acid serving as a product acid from the acid chamber, and obtaining a mixture of ammonia water and n-butylamine serving as recovered alkali from the alkali chamber. And (3) outputting hydrochloric acid as a product, concentrating ammonia water to a concentration of 15 wt%, and circularly conveying the concentrated ammonia water to the step (1) and the step (2). Wherein, the membrane stack of the bipolar membrane electrodialyzer has 10 membrane units, the adopted cation exchange membrane, anion exchange membrane and bipolar membrane (purchased from Beijing Tingting Membrane technology development Limited, the size of the membrane stack is 200 x 400 mm) are homogeneous styrene ion exchange membranes, the voltage is constant at 20V in the bipolar membrane electrodialysis process, and the temperature of the recovered ammonium chloride solution fed into the bipolar membrane electrodialyzer is 20 ℃.
(6) Concentrating: stirring the desalted aluminum sol obtained in the step (4) at a temperature of 85 ℃ to remove part of water to obtain a solution with a concentration of 19.9 wt% (based on Al) 2 O 3 Meter) of the aluminum sol product.
Of products based on aluminium sols 27 The Al NMR spectrum is similar to that of FIG. 1, with Al present at delta 60-61 13 The characteristic peak of monomeric aluminum does not exist at a position where delta is 0, and it can be seen that Al element is mainly Al 13 The form exists.
Example 4
(1) While stirring, 480g of a 15 wt% aqueous potassium hydroxide solution was slowly added to 750g of a 20 wt% aluminum chloride solution at ambient temperature (25 ℃ C., the same applies hereinafter), while stirring, to obtain a first reaction solution having a pH of 3.3, the temperature of the first reaction solution was raised to 50 ℃ C., and the reaction was stirred at that temperature for 0.5 hour;
(2) Introducing 200g of polyaluminum chloride (Al element content 51.06 g) into the heated solution obtained in step (2) with stirring, and adding 220g of a 15 wt% aqueous solution of potassium hydroxide to obtain a second reaction solution having a pH of 4.5;
(3) The temperature of the second reaction solution was raised to 70 ℃ and stirred at this temperature for 4.5 hours, then cooled to ambient temperature to give a concentration of 4.8 wt.% (expressed as Al) 2 O 3 Meter) of a salt-containing aluminium sol;
step (4), step (5) and step (6) were performed according to step (4), step (5) and step (6) of example 1, respectively. A concentration of 21% by weight (in terms of Al) is obtained 2 O 3 Meter) of the aluminum sol product.
Of sol products 27 The Al NMR spectrum is similar to that of FIG. 1, with Al present at delta 60-61 13 The characteristic peak of coordination aluminum of IV does not exist at the position where delta is 0, and the Al element is mainly Al 13 The form exists.
Example 5
The process of example 1 was followed except that the first reaction solution in step (1) and the second reaction solution in step (3) were both heated to 50 ℃ and the stirring reaction time in step (3) was extended to 8 hours. The concentration obtained in step (3) is 5.8 wt% (based on Al) 2 O 3 Meter) of a salt-containing aluminium sol. Step (4), step (5) and step (6) were performed according to step (4), step (5) and step (6) of example 1, respectively. A concentration of 21% by weight (in terms of Al) is obtained 2 O 3 Meter) of the aluminum sol product.
Of products based on aluminium sols 27 The Al NMR spectrum is similar to that of FIG. 1, with Al present at delta 60-61 13 The characteristic peak of monomeric aluminum does not exist at a position where delta is 0, and it can be seen that Al element is mainly Al 13 The form exists.
Example 6
The procedure of example 1 was followed except that the first reaction solution in step (1) and the second reaction solution in step (3) were both heated to 80 ℃. Step (4), step (5) and step (6) were performed according to step (4), step (5) and step (6) of example 1, respectively. A concentration of 21% by weight (in terms of Al) is obtained 2 O 3 Meter) of the aluminum sol product.
Of products based on aluminium sols 27 The Al NMR spectrum is similar to that of FIG. 1, with Al present at delta 60-61 13 The peak of monomeric aluminum is absent at a position where δ is 0, and it can be seen that the Al element is mainly Al 13 The form exists.
As can be seen from the above examples and comparative examples, the present invention is usedThe process of the invention does not need to introduce additional impurities in the preparation process of the aluminum sol, so the prepared aluminum sol has low impurity content and can produce high-quality aluminum sol products; the raw materials adopted by the process are low in price and high in utilization rate, so that the production cost is low; the whole production process has mild conditions, low reaction temperature and short reaction period. The Al element in the alumina sol prepared by the production process is mainly Al 13 The aluminum sol basically does not contain monomer aluminum, the existence of four-coordinate aluminum enables the aluminum sol to have better cohesiveness, and the aluminum sol can better keep the pore volume of the catalyst when being used in the catalyst, overcomes the phenomenon of pore blocking when the traditional aluminum sol is used in the catalyst, and in addition, the aluminum sol synthesized by the production process provided by the invention has higher content of alumina, and reduces the subsequent concentration pressure. The production process of the invention can not only produce high-quality alumina sol products, but also basically does not produce waste in the whole production process, thereby being a green and environment-friendly production process.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (36)
1. A process for producing an aluminium sol, the process comprising:
(1) Carrying out first contact on a first aluminum source and a first alkali source to obtain a first reaction solution, wherein the pH of the first reaction solution is 3-5;
(2) Carrying out second contact on the first reaction liquid, a second aluminum source and a second alkali source to obtain a second reaction liquid, wherein the pH value of the second reaction liquid is 3-4.5;
(3) Carrying out second ageing on the second reaction solution to obtain salt-containing aluminum sol, wherein the second ageing is carried out at the temperature of not more than 100 ℃;
(4) Carrying out common electrodialysis on the salt-containing aluminum sol to obtain aluminum sol and recycling salt;
(5) Subjecting the recovered salt to bipolar membrane electrodialysis to respectively obtain a product acid and a recovered alkali, and recycling at least part of the recovered alkali for the step (1) and/or the step (2);
the first and second aluminum sources are each independently an aluminum salt and/or an aluminum isopropoxide;
the first and second alkali sources are each independently selected from the group consisting of alkali metal hydroxide, NH 3 ·H 2 O and an organic base.
2. The process of claim 1, wherein,
the aluminum salt is selected from at least one of aluminum chloride, polyaluminum chloride, aluminum nitrate and aluminum sulfate.
3. The process of claim 1, wherein,
the first aluminum source is aluminum chloride;
the second aluminum source is selected from at least one of aluminum chloride, polyaluminum chloride and aluminum isopropoxide.
4. The process of claim 3, wherein,
the second aluminum source is polyaluminum chloride.
5. The process of claim 3, wherein,
the first aluminum source is used in the form of a solution.
6. The process of claim 1, wherein,
the alkali metal hydroxide is sodium hydroxide and/or potassium hydroxide;
the organic base is at least one selected from the group consisting of n-butylamine, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.
7. The process of any of claims 1-6, wherein the total amount of the first and second alkalinity sourcesThe mass ratio to the total amount of the first aluminum source and the second aluminum source is (0.2-1.5): 1, the first and second alkali sources are substituted with OH - And/or N, wherein the first aluminum source and the second aluminum source are calculated by aluminum element.
8. The process of claim 7, wherein the mass ratio of the total amount of the first and second soda sources to the total amount of the first and second aluminum sources is (0.3-1): 1, the first and second alkali sources are OH - And/or N, wherein the first aluminum source and the second aluminum source are calculated by aluminum elements.
9. The process according to any one of claims 1 to 6,
the mass ratio of the first aluminum source to the second aluminum source is (0.1-2): 1.
10. the process of claim 9, wherein,
the mass ratio of the first aluminum source to the second aluminum source is (0.3-1.5) calculated by aluminum element: 1.
11. the process of claim 10, wherein,
the mass ratio of the first aluminum source to the second aluminum source is (0.5-1) calculated by aluminum element: 1.
12. the process according to any one of claims 1 to 6, wherein the pH of the first reaction liquid is 3 to 4.5.
13. The process according to any one of claims 1 to 6,
the process also comprises the following steps: and (2) carrying out first aging on the first reaction solution in the step (1), and then carrying out the step (2).
14. The process of claim 13, wherein,
the first ageing is carried out at a temperature of 30-95 ℃;
the first aging time is 10-120min.
15. The process of claim 14, wherein,
the first ageing is carried out at a temperature of 30-70 ℃;
the first aging time is 20-60min.
16. The process of claim 15, wherein,
the first aging is carried out at a temperature of 35-55 ℃.
17. The process of claim 13, wherein the second aging temperature is at least 10 ℃ higher than the first aging temperature.
18. The process of claim 17, wherein the second aging temperature is 10-35 ℃ higher than the first aging temperature.
19. The process of claim 18, wherein the second aging temperature is 15-30 ℃ higher than the first aging temperature.
20. The process according to any one of claims 1 to 6,
the second ageing is carried out at a temperature of 40-95 ℃;
the second aging time is 3-10h.
21. The process of claim 20, wherein,
the second ageing is carried out at a temperature of 40-80 ℃;
the time of the second aging is 4-8h.
22. The process of claim 21, wherein,
the second aging is carried out at a temperature of 60-80 ℃.
23. The process according to any one of claims 1 to 6,
the pH of the second reaction solution is 3.3 to 4.5.
24. The process as claimed in any one of claims 1 to 6, wherein the electrodialyzer membrane stack for the general electrodialysis has at least one membrane unit, wherein the membranes in the membrane unit are an anion exchange membrane and a cation exchange membrane, the anion exchange membrane and the cation exchange membrane are arranged at intervals, the internal space of the membrane unit is divided into a desalting chamber and a concentrating chamber, the salt-containing alumina sol enters the desalting chamber, water enters the concentrating chamber, the alumina sol is obtained from the desalting chamber, and the salt is recovered from the concentrating chamber in the general electrodialysis process.
25. A process as defined in claim 24 wherein the conditions of the common electrodialysis include: the electrolyte content in the polar liquid introduced into the cathode chamber and the anode chamber of the electrodialyzer is the same or different and is 1-15 wt%; during the electrodialysis, the current density is 5-1000 amperes per square meter.
26. The process of claim 25, wherein the conditions of the common electrodialysis comprise: the electrolyte content in the electrode solution introduced into the cathode chamber and the anode chamber of the electrodialyzer is the same or different and is 3-10 wt% respectively; during the electrodialysis, the current density is 10-500 amperes per square meter.
27. The process of claim 26, wherein,
the conditions of the ordinary electrodialysis include: the concentration of the electrolyte in the polar liquid fed into the cathode chamber of the electrodialyser is 5-7 wt%; during the electrodialysis, the current density is 20-35 amperes per square meter.
28. The process of claim 25, wherein,
the electrolyte is at least one of ammonium sulfate, sodium nitrate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium nitrate, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium hydroxide, potassium hydroxide, formic acid, acetic acid, sodium formate, potassium formate and quaternary ammonium type electrolyte.
29. A process as claimed in any one of claims 1 to 6, wherein the salt-containing aluminium sol subjected to conventional electrodialysis has an aluminium content of 2 to 10% by weight, the aluminium being Al 2 O 3 And (6) counting.
30. A process as claimed in claim 29, wherein the salt-containing aluminium sol subjected to conventional electrodialysis has an aluminium content of 4-9% by weight, expressed as Al 2 O 3 And (6) counting.
31. The process according to claim 1, wherein the bipolar membrane electrodialysis employs a bipolar membrane electrodialyzer having at least one membrane unit, wherein the membranes of the membrane unit are a bipolar membrane, an anion exchange membrane and a cation exchange membrane, the bipolar membrane, the anion exchange membrane and the cation exchange membrane partition the interior space of the membrane unit into an acid compartment, a salt compartment and a base compartment, the salt compartment being located between the acid compartment and the base compartment, the recovered salt being passed into the salt compartment, and water being passed into the acid compartment and the base compartment, respectively, and wherein during bipolar membrane electrodialysis, the product acid is obtained from the acid compartment and the recovered base is obtained from the base compartment.
32. The process of claim 31, wherein,
the conditions of the bipolar membrane electrodialysis comprise: the concentration of electrolyte in polar solution introduced into the cathode chamber and the anode chamber of the bipolar membrane electrodialyzer is the same or different and is 1-10 wt%; in the bipolar membrane electrodialysis process, the voltage is 5-30V.
33. The process of claim 32, wherein,
the conditions of the bipolar membrane electrodialysis comprise: the concentrations of electrolytes in polar liquids introduced into a cathode chamber and an anode chamber of the bipolar membrane electrodialyzer are the same or different and are respectively 3-8 wt%; in the bipolar membrane electrodialysis process, the voltage is 8-25V.
34. The process of claim 33, wherein,
the conditions of the bipolar membrane electrodialysis comprise: in the bipolar membrane electrodialysis process, the voltage is 10-20V.
35. The aluminum sol obtained by the production process according to any one of claims 1 to 34, wherein the aluminum sol is obtained by using Al 13 Al element exists in the form of 50% or more of Al element, and Al element exists in the form of single aluminum in the form of 10% or less of Al element.
36. The aluminum sol according to claim 35, wherein,
the mass ratio of aluminum to chlorine of the aluminum sol is 1-1.6.
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