CN111484032A - Method for preparing molecular sieve by using white mud as raw material - Google Patents

Method for preparing molecular sieve by using white mud as raw material Download PDF

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CN111484032A
CN111484032A CN201910080200.5A CN201910080200A CN111484032A CN 111484032 A CN111484032 A CN 111484032A CN 201910080200 A CN201910080200 A CN 201910080200A CN 111484032 A CN111484032 A CN 111484032A
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molecular sieve
clinker
white mud
silicon
solution
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闫学良
孙琦
刘汇东
张中华
常彬杰
高星
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China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
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China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/14—Type A
    • C01B39/16—Type A from aqueous solutions of an alkali metal aluminate and an alkali metal silicate excluding any other source of alumina or silica but seeds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/20—Faujasite type, e.g. type X or Y
    • C01B39/22—Type X
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/36—Pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
    • C01B39/38—Type ZSM-5
    • C01B39/40—Type ZSM-5 using at least one organic template directing agent

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  • Silicates, Zeolites, And Molecular Sieves (AREA)

Abstract

The invention relates to a method for preparing a molecular sieve by taking white mud as a raw material, which comprises the following steps: leaching the white mud with alkali liquor and separating to obtain silicon solution and desiliconized white mud; mixing the desiliconized white mud with an auxiliary agent M and an auxiliary agent Q to prepare raw slurry, sintering the raw slurry to form clinker, and dissolving out the clinker to obtain clinker dissolving liquid; mixing the clinker dissolved liquid and at least a part of the silicon dissolved liquid, carrying out first crystallization, and separating to obtain a 4A type molecular sieve or a 13X type molecular sieve and a first filtrate; mixing the first filtrate, a template agent and optional residual silica solution, performing second crystallization, and separating to obtain a ZSM-5 type molecular sieve and a second filtrate; wherein, the auxiliary M is at least one of quick lime, limestone, magnesium oxide and magnesium carbonate, and the auxiliary Q is sodium carbonate and/or potassium carbonate. The method can fully utilize the white mud as resources without additionally adding a silicon source and an aluminum source, and realizes the complete consumption of the extracted silicon element and the extracted aluminum element.

Description

Method for preparing molecular sieve by using white mud as raw material
Technical Field
The invention relates to the field of molecular sieves, in particular to a method for preparing a molecular sieve by taking white mud as a raw material.
Background
The fly ash is solid waste in the production process of a power plant, and has large discharge amount and serious pollution. Since fly ash contains useful mineral resources such as alumina, many studies have been made on the comprehensive utilization of fly ash. The 'one-step acid dissolution method' pioneered by Shenhua group is feasible in industrialized test verification technology, and is expected to be popularized in a large scale due to the characteristics of short process flow and the like. However, after the aluminum is extracted by the method, a large amount of tailings, commonly called white mud, is generated, and calculated by the process of extracting aluminum oxide by the acid method of fly ash in the quasi-gel region, 1 ton of aluminum oxide is produced by every 2.5 tons of fly ash, and simultaneously 1.5 tons of white mud is discharged, so that the emission is large, and the environment is polluted.
There has been some prior art relating to the reuse of lime mud, CN103738977A discloses a process for preparing a type 4A molecular sieve starting from lime mud, said process comprising: adding a sodium hydroxide solution into the white mud, reacting, filtering and collecting filtrate; and adding sodium metaaluminate into the filtrate, and preparing the 4A type molecular sieve by a hydrothermal synthesis process.
CN103663487A discloses a method for synthesizing a Y-type molecular sieve by using white mud as a raw material, which comprises the following steps: preparing a sodium metaaluminate structure directing agent; leaching the white mud with a sodium hydroxide solution; adding water glass, sodium metaaluminate, sodium hydroxide and deionized water into the leaching filtrate to prepare reaction gel; crystallizing, washing and drying to obtain the solid Y-shaped molecular sieve. However, both of the above methods have problems that the raw material of the white mud cannot be sufficiently used to some extent and a large amount of residue is generated, and particularly, about 15 to 20% of alumina in the white mud is discarded as waste, and an aluminum source needs to be additionally added in the preparation process of the molecular sieve.
The preparation of 4A type molecular sieve from residue of aluminum sulfate extracted from fly ash discloses that the 4A type molecular sieve is synthesized by solid phase synthesis method using residue of aluminum sulfate extracted from fly ash as raw material, and the 4A type molecular sieve is prepared by uniformly mixing residue of aluminum extracted from fly ash by acid method with alkali, roasting and crystallizing. Although the method realizes full utilization of the white mud through solid-phase synthesis, the method still needs to add aluminum source-aluminum hydroxide, needs a large amount of caustic soda, has high cost, large reaction energy consumption and high requirement on equipment, and is not easy to realize in actual production. No independent, perfect and mild-condition method for recycling the white mud is reported in the prior art.
Therefore, a simple method for preparing the molecular sieve, which can more effectively utilize the white mud without additionally adding a silicon source and an aluminum source, has low requirements on equipment and can realize complete consumption of the white mud, is urgently needed.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, white mud cannot be fully recycled, a silicon source and an aluminum source are required to be additionally added, the requirement on equipment is high, and the like, and provides a method for preparing a molecular sieve by using the white mud as a raw material.
The inventor of the invention finds in research that the material composition of the white mud has specificity compared with the fly ash: the silicon content is more enriched than that of common fly ash, the aluminum content is obviously reduced, and acid soluble elements such as Fe, Mg and the like are greatly removed in the process of extracting aluminum by an acid method, wherein SiO2With Al2O3The molar ratio (hereinafter, it may be expressed as a silicon-aluminum ratio, or SiO)2/Al2O3) About 10: 1. the mole ratio of silicon and aluminum in the white mud can not be completely matched with the high-silicon molecular sieve and the low-silicon molecular sieve, and if the residue of extracting aluminum by the acid method of fly ash is directly used for synthesizing the low-silicon molecular sieve (such as the 4A molecular sieve)The silicon-aluminum ratio is about 2-3; 13X type molecular sieve, the silicon-aluminum ratio is about 2-3), Si is obviously excessive, and an aluminum source needs to be added; when the Al-Si-Al-Si-. On the other hand, in the white mud, low-activity components such as mullite, quartz, anatase and the like are further enriched compared with the original fly ash, so that the improvement of the utilization rate of the white mud is restricted. Therefore, it is necessary to consider the above factors comprehensively how to reasonably and better utilize the silicon and aluminum resources in the white mud and prepare the molecular sieve without adding additional silicon and aluminum sources. The inventor proposes the method of the invention to improve the utilization rate of the white mud and realize the complete consumption of the white mud through the co-production of the 4A type molecular sieve (or the 13X type molecular sieve) and the ZSM-5 type molecular sieve.
The first aspect of the invention provides a method for preparing a molecular sieve by taking white mud as a raw material, which comprises the following steps:
(1) leaching the white mud with alkali liquor and separating to obtain silicon solution and desiliconized white mud;
(2) mixing the desiliconized white mud with an auxiliary agent M and an auxiliary agent Q to prepare raw slurry, sintering the raw slurry to form clinker, and dissolving out the clinker to obtain clinker dissolving liquid;
(3) mixing the clinker dissolving liquid and at least a part of the silicon dissolving liquid, carrying out first crystallization, and separating to obtain a 4A type molecular sieve or a 13X type molecular sieve and a first filtrate;
(4) and carrying out second crystallization on the first filtrate, the template agent and the optional residual silicon solution, and separating to obtain the ZSM-5 type molecular sieve and a second filtrate.
The auxiliary M is at least one selected from quick lime, limestone, magnesium oxide and magnesium carbonate, and the auxiliary Q is sodium carbonate and/or potassium carbonate.
The method can fully utilize the white mud as resources, and maximally extract the silicon element and the aluminum element from the white mud, so that the clinker dissolved-out residue amount is less, and the clinker dissolved-out residue contains less aluminum element and less silicon element; preparing a low silicon-aluminum ratio molecular sieve and a high silicon-aluminum ratio molecular sieve under the condition of not additionally adding a silicon source and an aluminum source, and completely absorbing the extracted silicon element and aluminum element by a series preparation process of the molecular sieves; meanwhile, the method has low requirement on equipment, and can use the existing equipment to prepare the molecular sieve.
Drawings
FIG. 1 is a schematic flow diagram of one embodiment of the process of the present invention.
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 method for preparing a molecular sieve by taking white mud as a raw material, which comprises the following steps:
(1) leaching the white mud with alkali liquor and separating to obtain silicon solution and desiliconized white mud;
(2) mixing the desiliconized white mud with an auxiliary agent M and an auxiliary agent Q to prepare raw slurry, sintering the raw slurry to form clinker, and dissolving out the clinker to obtain clinker dissolving liquid;
(3) mixing the clinker dissolving liquid and at least a part of the silicon dissolving liquid, carrying out first crystallization, and separating to obtain a 4A type molecular sieve or a 13X type molecular sieve and a first filtrate;
(4) carrying out second crystallization on the first filtrate, the template agent and the optional residual silicon solution, and separating to obtain a ZSM-5 type molecular sieve and a second filtrate;
the auxiliary agent M is at least one selected from quick lime, limestone, magnesium oxide and magnesium carbonate, and the auxiliary agent Q is sodium carbonate and/or potassium carbonate.
In the invention, the white mud is tailings generated after aluminum is extracted from the fly ash by a one-step acid dissolution method. The white mud mainly comprises: SiO 22、Fe2O3、Al2O3And TiO2. E.g. in lime mud, SiO2May be present in an amount of about 70-80 wt.%, Al2O3May be present in an amount of about 10-15 wt%, TiO2May be present in an amount of about 3 to about 8 weight percent.
In the process according to the invention, in step (1), the lime mud is leached with a lye, the leaching being carried out in order to achieve the removal of silicon from the lime mud to obtain a solution of silicon, the lye used being an aqueous solution of a strong base which can be selected according to the prior art, for example an alkali metal and/or alkaline earth metal hydroxide, preferably an aqueous solution of potassium hydroxide and/or sodium hydroxide, the concentration of the lye being adjusted as required, for example 60 to 300 g/L, the lye being used in an amount of 2 to 6m per 1000kg of the lime mud3。
In the method of the present invention, in step (1), the leaching conditions are: the temperature is 50-150 ℃, preferably 95-110 ℃; the time is 0.5-5 h.
In the method, in the step (1), the white mud is leached and separated to obtain a silicon solution and desiliconized white mud. The desiliconized white mud mainly contains Al2O3、SiO2And TiO2In which Al is2O3In an amount of about 40-70 wt%, SiO2Is present in an amount of about 5-25% by weight, the major phases being mullite and anatase.
In the method of the present invention, the step (2) is to activate the aluminum element in the desilicated white mud to extract the aluminum element from the desilicated white mud. In the process of preparing the raw slurry, the addition amounts of the auxiliary agent M and the auxiliary agent Q can be determined according to the components of the desiliconized white mud, and the amounts of the auxiliary agent M and the auxiliary agent Q are adjusted to enable the raw slurry to have the composition of [ A ]2O]/([Al2O3]+[Fe2O3]) The molar ratio is 0.5-2.2 in terms of [ EO ]]/([SiO2]+[TiO2]) The molar ratio is 0.5-2.5, and the water content is 35-50 wt%, wherein A2O and EO are in the form of oxides of the auxiliary Q and the auxiliary M, respectively. Preferably, the composition of the raw slurry is [ A ]2O]/([Al2O3]+[Fe2O3]) The molar ratio is 1.5-2.2 in terms of [ EO ]]/([SiO2]+[TiO2]) In a molar ratio of 0.8-1.2 and a water content of 35-50 wt.%, in the process according to the invention, the auxiliaries M and Q can be added in step (2) in any suitable form for preparing a green slurry, for example in solid form or in the form of an aqueous solution.
In the method of the invention, in step (2), the sintering is carried out to activate the aluminum element in the desilicated white mud, and the alumina insoluble in the desilicated white mud and existing in mullite phase is sintered and converted into soluble salt such as sodium aluminate. In the invention, the amount of the auxiliary M and the auxiliary Q is set to be [ A ] in the composition of the raw slurry2O]/([Al2O3]+[Fe2O3]) The molar ratio is 0.5-2.2 in terms of [ EO ]]/([SiO2]+[TiO2]) The molar ratio is 0.5-2.5, which is set in order to react as much as possible of the element Al with the auxiliary Q during sintering to form a soluble salt containing the element Al. Since the presence of the element Fe also consumes a part of the auxiliary Q during sintering, the presence of the element Fe also needs to be taken into account. At the same time set with [ EO]/([SiO2]+[TiO2]) The molar ratio is 0.5-2.5, which is to make silicon element react with the assistant M to generate silicate during sintering, so as to release element Al to react with the assistant Q. The sintering conditions are as follows: the temperature is 1000-1300 ℃, preferably, the temperature is 1000-1150 ℃; the time is 0.5-2 h.
In the method of the present invention, in the step (2), after the clinker is sintered to form the clinker, the clinker is subjected to dissolution, wherein the dissolution comprises placing the clinker in water or an aqueous solution, the aqueous solution is a solution using water as a solute, the water or the aqueous solution is used for dissolving the aluminum soluble salt in the clinker, the aqueous solution can be arbitrarily selected according to the prior art as long as the purpose of dissolving the aluminum soluble salt in the clinker is achieved, preferably, the aqueous solution is selected from dilute solution of sodium hydroxide, dilute solution of potassium hydroxide, aqueous solution of sodium carbonate, aqueous solution of potassium carbonate or a mixed solution of any combination of the sodium hydroxide and the potassium hydroxide, and the concentration of the dilute solution of sodium hydroxide or potassium hydroxide can be adjusted as required, and for example, the concentration can be 10-30 g/L.
In the method of the present invention, in the step (2), the dissolution conditions are: the temperature is 60-90 ℃ and the time is 0.5-3 h. The dissolution is intended to extract the aluminium element from the clinker in the form of soluble aluminium salts. And dissolving the clinker to obtain clinker dissolving liquid and clinker dissolving residues. The clinker leaching solution mainly contains aluminum soluble salt such as sodium aluminate and/or potassium aluminate, the clinker leaching residue mainly contains calcium silicate and titanium-rich ore, and when the content of titanium element in the clinker leaching residue exceeds 30 wt%, the clinker leaching residue can be used as raw material for extracting silicon dioxide.
In a preferred embodiment of the method of the invention, the amounts of the auxiliary M and the auxiliary Q are adjusted so that [ A ] is the ratio of the raw slurry composition2O]/([Al2O3]+[Fe2O3]) Calculated as a molar ratio of 2, [ EO ]]/([SiO2]+[TiO2]) The calculated molar ratio is 1, the prepared raw slurry can be sintered at a lower temperature, for example, at the temperature of 1000-1150 ℃, and the obtained clinker is less in clinker dissolution residue after dissolution.
In another preferred embodiment of the method of the present invention, the amounts of the auxiliary M and the auxiliary Q are adjusted so that [ A ] is the ratio of the raw slurry composition2O]/([Al2O3]+[Fe2O3]) In a molar ratio of 1, with [ EO ]]/([SiO2]+[TiO2]) The calculated molar ratio is 2, the prepared raw slurry is sintered at the temperature of 1200-1300 ℃, the obtained clinker is dissolved out to generate clinker dissolved-out residues, and Al in the clinker dissolved-out residues2O3The content of (A) is small.
In the present invention, the method may further comprise pulverizing the clinker, preferably to a particle size of 3-8mm, prior to the dissolution step.
In the method, in the step (3), the clinker dissolution liquid and at least a part of the silicon dissolution liquid are mixed, a first crystallization reaction is carried out, and a 4A type molecular sieve or a 13X type molecular sieve and a first filtrate are obtained through filtration. The dosage of clinker dissolving liquid and silicon dissolving liquid is adjusted to obtain the 4A type molecular sieve or the 13X type molecular sieve.
In a preferred embodiment of the method of the present invention, in step (3), the clinker dissolution liquid and 20-100 wt% of the silicon dissolution liquid are mixed and subjected to first crystallization, and the 4A type molecular sieve or 13X type molecular sieve is obtained through separation, and the first filtrate.
In the method of the invention, Al is used in the first filtrate2O3The calculated Al content is 1-5 g/L, and the condition of the first crystallization can be selected according to the molecular sieve to be prepared and the prior art.
As discovered by the inventor, after the first filtrate, the template and the optional residual silicon solution are mixed, SiO in the obtained mixed solution2/Al2O3The molar ratio is 20-120, Na2O/Al2O3The mixed liquid can be used for preparing the ZSM-5 type molecular sieve through crystallization reaction, wherein the molar ratio is 2-12. The templating agent may be selected according to the prior art, and may be selected, for example, from at least one of tetraethylammonium hydroxide, tetrapropylammonium bromide, isopropylamine, tetraethylammonium hydroxide, and di-n-propylamine.
In the present invention, the "optional remaining silicon solution" is understood to be: 1) if clinker dissolution liquid is used for crystallization with a part of the silicon dissolution liquid in the step (3) to prepare a 4A type molecular sieve or a 13X type molecular sieve, the optional remaining silicon dissolution liquid is understood as the silicon dissolution liquid remaining after the step (3) is carried out, and the process is shown in figure 1; 2) if the clinker dissolution liquid and the whole silicon dissolution liquid are used for preparing the 4A type molecular sieve or the 13X type molecular sieve through crystallization reaction in the step (3), the optional residual silicon dissolution liquid is understood as not using the silicon dissolution liquid.
In the present invention, in the step (4), the conditions of the second crystallization may be adjusted according to the prior art. After the second crystallization, the main component of the second filtrate obtained by separation is sodium hydroxide solution and Al2O3The calculated content of the aluminum element is 0-1 g/L. in a preferred embodiment, the second filtrate can be returned to the step (1) as alkali liquor to remove the silicon element in the lime mud.
According to the method, the steps of dissolving silicon in the alkali liquor and dissolving aluminum in the sintered clinker are adopted to extract all or as much as possible silicon and aluminum in the white mud, so that the obtained clinker is less in dissolved residue, and the residual silicon and aluminum in the clinker dissolved residue are less, so that the white mud is fully recycled; and the total consumption of the extracted silicon element (silicon dissolving liquid) and aluminum element (clinker dissolving liquid) is realized by the serial preparation process of the low-silicon-aluminum-ratio molecular sieve and the high-silicon-aluminum-ratio molecular sieve under the condition of not additionally adding a silicon source and an aluminum source; meanwhile, the method has low requirement on equipment, and can use the existing equipment.
The present invention will be described in detail below by way of examples.
The white mud used in the examples is waste residue produced by extracting alumina from fly ash from power plants in the inner Mongolia, quasi-Gill area by a one-step acid dissolution method. The content of silicon oxide in the white mud is 78.7 percent, the content of aluminum oxide is 13.4 percent, and the content of titanium oxide is 5.2 percent; the main phase components are amorphous silicon dioxide, mullite and anatase, and the main components are shown in table 1.
Example 1
(1) Taking 1000g of white mud with the composition, and adding the white mud and the sodium hydroxide solution with the concentration of 170 g/L according to the ratio of 1000kg to 4m3The mixture is stirred and reacted for 2 hours at the temperature of 90 ℃, and then filtered and washed to obtain a silicon solution (the main component is a sodium silicate solution containing a small amount of sodium aluminate solution) and desiliconized white mud, wherein the main components of the desiliconized white mud are shown in table 1, the silicon oxide content is 23.2%, the aluminum oxide content is 56.7%, the titanium oxide content is 11.7%, and the main phases are mullite and anatase.
(2) Mixing desiliconized white mud with limestone and sodium carbonate solution to prepare raw slurry, wherein the raw slurry is composed of Na2O]/([Al2O3]+[Fe2O3]) Calculated molar ratio is 2, calculated as [ CaO ]]/([SiO2]+[TiO2]) The calculated molar ratio is 1, the water content is 40 percent, the raw slurry is sprayed into a rotary kiln to be sintered for 1.5 hours at the temperature of 1000 ℃, the clinker generated by sintering is crushed to the particle size of 3-8mm, the clinker is dissolved out for 1 hour at the temperature of 75 ℃ in water, and the generated clinker is dissolved outThe main component of the solution is sodium aluminate, 185g of clinker dissolution residues are generated after dissolution, and the main component is shown in table 1.
(3) Mixing 50 wt% of the silicon-dissolving solution and clinker-dissolving solution, and stirring (adding [ Na ] into the mixed solution)2O]/[SiO2]The molar ratio is 1.3 in terms of [ SiO ]2]/[Al2O3]The calculated molar ratio is 2.2), carrying out first crystallization, then washing, filtering and drying to obtain the molecular sieve and first filtrate, wherein the molecular sieve is shown to be the 4A type molecular sieve through XRD test.
(4) Mixing the rest of the silicon solution, the first filtrate and a template agent tetrapropylammonium bromide for second crystallization, and then washing and filtering to obtain a molecular sieve and a second filtrate (Al is used in the second filtrate)2O3The calculated aluminum element content is 0.1 g/L), the obtained molecular sieve is shown to be a ZSM-5 type molecular sieve through XRD test, and the second filtrate is returned to the silicon dissolving process in the step (1).
Example 2
A molecular sieve was prepared as described in reference to example 1, except that:
(3) mixing 70 wt% silicon solution and clinker solution under stirring (adding Na into the mixture)2O]/[SiO2]The molar ratio is 1.4 in terms of [ SiO ]2]/[Al2O3]The calculated molar ratio is 4), carrying out first crystallization, then washing and filtering to obtain a molecular sieve and a first filtrate, wherein the molecular sieve is shown to be the 13X type molecular sieve through XRD test.
(4) Mixing the rest silicon solution, the first filtrate and template agent tetrapropylammonium bromide for crystallization, washing and filtering to obtain the molecular sieve and the second filtrate (wherein Al is used as the raw material)2O3Aluminum source content of 0.5 g/L), the obtained molecular sieve shows a ZSM-5 type molecular sieve by XRD test, and the second filtrate is returned to the step of dissolving silicon in the step (1).
Example 3
A molecular sieve was prepared as described in reference to example 1, except that:
(3) mixing all the silicon-dissolving liquid and clinker dissolving liquid (adding Na into the mixed liquid)2O]/[SiO2]The molar ratio is 1.8. With [ SiO ]2]/[Al2O3]The calculated molar ratio is 5), carrying out first crystallization, then washing and filtering to obtain a molecular sieve and a first filtrate, wherein the molecular sieve is shown to be a 13X type molecular sieve through XRD test.
(4) Mixing the rest silicon solution, the first filtrate and template agent tetrapropylammonium bromide for crystallization, washing and filtering to obtain the molecular sieve and the second filtrate (wherein Al is used as the raw material)2O3Aluminum source content of 0.5 g/L), the obtained molecular sieve shows a ZSM-5 type molecular sieve by XRD test, and the second filtrate is returned to the step of dissolving silicon in the step (1).
Example 4
A molecular sieve was prepared as described in reference to example 1, except that:
(3) mixing 20 wt% silicon solution and clinker solution under stirring (Na is added to the mixture)2O]/[SiO2]The molar ratio is 1.1 in terms of [ SiO ]2]/[Al2O3]The calculated molar ratio is 2), carrying out first crystallization, then washing and filtering to obtain the molecular sieve and first filtrate, wherein the molecular sieve is shown to be the 4A type molecular sieve through XRD test.
(4) Mixing the rest silicon solution, the first filtrate and template agent tetrapropylammonium bromide for crystallization, washing and filtering to obtain the molecular sieve and the second filtrate (wherein Al is used as the raw material)2O3Aluminum source content of 0.8 g/L), the obtained molecular sieve shows a ZSM-5 type molecular sieve by XRD test, and the second filtrate is returned to the step of dissolving silicon in the step (1).
Example 5
A molecular sieve was prepared by the method described in reference to example 1, except that, in the step (2), desilicated white mud was mixed with quicklime and a sodium carbonate solution to prepare raw slurry so that the composition of the raw slurry was made of [ Na ]2O]/([Al2O3]+[Fe2O3]) The molar ratio is 1 in terms of [ CaO ]]/([SiO2]+[TiO2]) The calculated molar ratio is 2, the water content is 42 percent, the raw slurry is sprayed into a rotary kiln to be sintered for 1h at 1250 ℃, the dissolved clinker residue generated after the clinker is dissolved out is obtained and is 240g after hydrothermal dealkalization, and the dissolved clinker is dissolved outThe main components of the residue are shown in Table 1. Al in the second filtrate2O3The calculated aluminum element content is 1 g/L.
Example 6
Molecular sieves were prepared as described in example 1, except that raw slurry was prepared by mixing desiliconized white mud with magnesium carbonate and potassium carbonate solution in step (2) so that the composition of the raw slurry was represented by [ K ]2O]/([Al2O3]+[Fe2O3]) The molar ratio is 2 in terms of [ MgO]/([SiO2]+[TiO2]) The calculated molar ratio is 1, the water content is 42 percent, the raw slurry is sprayed into a rotary kiln to be sintered for 1.5 hours at 1150 ℃, the clinker generated by sintering is crushed to the particle size of 3-8mm, the clinker is dissolved out for 1 hour at 75 ℃ in a potassium hydroxide dilute solution (the concentration is 15 g/L), the main component of the generated clinker dissolution liquid is potassium aluminate, and the dissolved clinker residue is 215g after dissolution, wherein the main component is shown in the table 1.
As a result, Al is contained in the second filtrate2O3The aluminum source content was 0.5 g/L.
Example 7
A molecular sieve was prepared as described in reference to example 1, except that,
in step (2), the green slurry prepared according to example 1 was sprayed into a rotary kiln and sintered at 1300 ℃ for 2 hours to produce 198g of clinker-dissolving residue, the main components of which are shown in Table 1.
As a result, Al is contained in the second filtrate2O3The aluminum source content was 0.6 g/L.
TABLE 1
Clinker leaching residue component Example 1 Example 5 Example 6 Example 7
Total weight/g 185 240 215 198
Al2O3Per weight percent 1.35 1.2 1.25 1.38
SiO2Per weight percent 35.2 25.3 25.9 35.5
TiO2Per weight percent 27.6 21.7 21.9 26.7
Fe2O3Per weight percent 2.7 1.8 2.2 2.6
Na2O/weight% 1.5 1.2 1.4 1.7
As can be seen from the results in table 1, the method of the present invention can maximize resource utilization of the white mud, maximize extraction of silicon and aluminum from the white mud, and simultaneously, no additional silicon source and aluminum source are required in the preparation of the molecular sieve. The method of the invention can remove Al in the white mud2O3The content is reduced to below 2 percent, and the total consumption of the silicon dissolving liquid and the clinker dissolving liquid can be realized by preparing the molecular sieve through the process flow of the invention.
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 (10)

1. A method for preparing a molecular sieve by taking white mud as a raw material comprises the following steps:
(1) leaching the white mud with alkali liquor and separating to obtain silicon solution and desiliconized white mud;
(2) mixing the desiliconized white mud with an auxiliary agent M and an auxiliary agent Q to prepare raw slurry, sintering the raw slurry to form clinker, and dissolving out the clinker to obtain clinker dissolving liquid;
(3) mixing the clinker dissolving liquid and at least a part of the silicon dissolving liquid, carrying out first crystallization, and separating to obtain a 4A type molecular sieve or a 13X type molecular sieve and a first filtrate;
(4) mixing the first filtrate, a template agent and optionally the rest of the silica solution for second crystallization, and separating a product to obtain a ZSM-5 type molecular sieve and a second filtrate;
the auxiliary agent M is at least one selected from quick lime, limestone, magnesium oxide and magnesium carbonate, and the auxiliary agent Q is sodium carbonate and/or potassium carbonate.
2. The method according to claim 1, wherein in step (1), the lye is an aqueous solution of potassium hydroxide and/or sodium hydroxide, preferably the lye has a concentration of 60-300 g/L.
3. The method as claimed in claim 2, wherein, in the step (1), the alkali liquor is used in an amount of 2-6m with respect to 1000kg of the lime mud3。
4. The process according to claim 1, wherein in step (1) the leaching conditions are: the temperature is 50-150 ℃ and the time is 0.5-5 h.
5. The method according to claim 1, wherein in step (2), the amounts of desilicated white mud, auxiliary agent M and auxiliary agent Q are adjusted so that the composition of the raw slurry is [ A ]2O]/([Al2O3]+[Fe2O3]) The molar ratio is 0.5-2.2, preferably 1.5-2.2; with [ EO ]]/([SiO2]+[TiO2]) In a molar ratio of 0.5 to 2.5, preferably 0.8 to 1.2, where A2O and EO are in the form of oxides of the auxiliary Q and the auxiliary M, respectively.
6. The method according to claim 1, wherein, in step (2), the sintering conditions are: the temperature is 1000-1300 ℃, and preferably 1000-1150 ℃; the time is 0.5-2 h.
7. The method according to claim 1, wherein in step (2) the dissolution comprises placing the clinker in water or an aqueous solution, preferably the aqueous solution is selected from a mixed solution of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, potassium carbonate solution or any combination thereof.
8. The process according to claim 1 or 7, wherein in step (2), the conditions of the dissolution are: the temperature is 60-90 ℃ and the time is 0.5-3 h.
9. The method as claimed in claim 1, wherein, in step (3), the clinker dissolution liquid and 20-100 wt% of the silicon dissolution liquid are mixed and subjected to first crystallization, and a 4A type molecular sieve or a 13X type molecular sieve is separated, and a first filtrate is obtained.
10. The method of claim 1, wherein, in step (4), the templating agent is selected from at least one of tetraethylammonium hydroxide, tetrapropylammonium bromide, isopropylamine, tetraethylammonium hydroxide, and di-n-propylamine.
CN201910080200.5A 2019-01-28 2019-01-28 Method for preparing molecular sieve by using white mud as raw material Pending CN111484032A (en)

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