CN116282064A - 4A molecular sieve and preparation method thereof - Google Patents

4A molecular sieve and preparation method thereof Download PDF

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Publication number
CN116282064A
CN116282064A CN202310315193.9A CN202310315193A CN116282064A CN 116282064 A CN116282064 A CN 116282064A CN 202310315193 A CN202310315193 A CN 202310315193A CN 116282064 A CN116282064 A CN 116282064A
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molecular sieve
fly ash
granulation
stage
sio
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杜艳霞
李小燕
王强
赵飞燕
张艳娜
姬学良
张云峰
张玮琦
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Shenhua Zhunneng Resources Development and Utilisation Co Ltd
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Shenhua Zhunneng Resources Development and Utilisation Co Ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM

Abstract

The invention provides a 4A molecular sieve and a preparation method thereof. The preparation method comprises the following steps: sequentially granulating, aging and crystallizing a mixture of white mud, circulating fluidized bed fly ash and solid NaOH to obtain a 4A molecular sieve; wherein the white mud comprises 65 to 75 weight percent of SiO 2 12 to 20 weight percent of Al 2 O 3 0 to 0.2wt% of K 2 O and/or Na 2 O, 0-12 wt% loss on ignition, and the balance impurities; the circulating fluidized bed fly ash comprises 25 to 38 weight percent of SiO 2 40 to 55 weight percent of Al 2 O 3 0 to 0.5wt% of K 2 O and/or Na 2 O, 0-7wt% of loss on ignition, and the balance of impurities. The molecular sieve prepared by the method of the invention is granular, can be directly applied to the fields of chemical industry, medicine and the like, and has simple preparation process and low cost.

Description

4A molecular sieve and preparation method thereof
Technical Field
The invention relates to the field of molecular sieve preparation, in particular to a 4A molecular sieve and a preparation method thereof.
Background
The 4A molecular sieve is a cubic microporous molecular sieve with an aluminosilicate structure, and substances with the diameter smaller than 4A are sucked into crystals, so that the substances are separated from other substances, and the 4A molecular sieve has the structural characteristics of endowing the molecular sieve with special adsorption performance and is widely applied to chemical industry, medicines and impurity removal processes of chemicals. At present, the industrialized 4A molecular sieve is mostly prepared by adopting chemical reagents such as silicic acid, sodium silicate, sodium hydroxide and the like as raw materials, the purity of the raw materials is high, the prepared 4A molecular sieve has good performance, but the preparation cost of the 4A molecular sieve is high due to the high cost of the raw materials, so that the use cost of the 4A molecular sieve is increased. Therefore, searching for low cost raw materials to prepare 4A molecular sieves has become a focus of research.
Fly ash is a large amount of industrial solid waste in China, and the annual emission amount is up to 6 hundred million tons, so that the comprehensive utilization of the fly ash becomes a great way for solving the pollution caused by the emission of the fly ash. The main component of the fly ash is found to be SiO 2 And A1 2 O 3 The surface of the fly ash is in a porous structure, the specific surface area is large, the fly ash has certain surface activity, and the fly ash is a low-cost raw material for preparing the 4A molecular sieve. The white mud is solid waste residue generated by dissolving fly ash with hydrochloric acid to remove impurities, and the main component is SiO 2 And A1 which is poorly soluble in acid 2 O 3 Other impurities content not exceeding 5% (where TiO 2 About 4% by weight), and is more advantageous in preparing the 4A molecular sieve than fly ash with higher purity. Patent CN201811272197.9 discloses a method for preparing a 4A molecular sieve by taking white mud as a raw material, the method firstly carries out roasting treatment on the white mud, then carries out aluminum-silicon ratio adjustment and then melts with alkali, and finally carries out hydrothermal synthesis on molten clinker to prepare the molecular sieve. Patent CN201610228003.X discloses a method for preparing 4A molecular sieve by using white mud as raw material,the method comprises the steps of firstly, reacting white mud with alkali liquor to prepare silicon-rich filtrate, and then carrying out hydrothermal synthesis on the silicon-rich filtrate and alumina to prepare the molecular sieve. The preparation of the silicon-rich filtrate can produce hazardous waste solids containing a large amount of alkali liquor, the filtration after the hydrothermal synthesis can produce waste alkali liquor which cannot be reused and contains aluminum, the prepared molecular sieve is still powdery and cannot be directly used, and meanwhile, the overall process cost is higher.
Therefore, it is necessary to provide a preparation method of a 4A molecular sieve, so as to solve the problems that in the process of preparing the molecular sieve from white mud in the prior art, solid and liquid hazardous wastes are easy to generate, the prepared molecular sieve is powdery instead of granular, cannot be directly used, and the preparation process is complex and has high cost.
Disclosure of Invention
The invention mainly aims to provide a preparation method of a 4A molecular sieve, which aims to solve the problems that solid and liquid hazardous wastes are easy to generate in the process of preparing the molecular sieve from white mud in the prior art, the prepared molecular sieve is powdery instead of granular, cannot be directly used, and the preparation process is complex and has high cost.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a 4A molecular sieve, the method comprising: sequentially granulating, aging and crystallizing the mixture of the white mud, the circulating fluidized bed fly ash and the solid NaOH to obtain a 4A molecular sieve; wherein the white mud comprises 65 to 75 weight percent of SiO 2 12 to 20 weight percent of Al 2 O 3 0 to 0.2wt% of K 2 O and/or Na 2 O, 0-12 wt% loss on ignition, and the balance impurities; the circulating fluidized bed fly ash comprises 25 to 38 weight percent of SiO 2 40 to 55 weight percent of Al 2 O 3 0 to 0.5wt% of K 2 O and/or Na 2 O, 0-7wt% of loss on ignition, and the balance of impurities.
Preferably, the granulation is carried out in a granulator; and the granulation comprises a first granulation stage, wherein the stirring speed of the first granulation stage is 3700-4000 r/min, and the stirring time is 10-20 min.
Preferably, the granulation further comprises a second granulation stage after the first granulation stage, wherein the stirring rate of the second granulation stage is 3300-3500 r/min and the stirring time is 10-20 min.
Preferably, the granulation further comprises a third granulation stage after the second granulation stage, wherein the stirring rate of the third granulation stage is 1500-2000 r/min and the stirring time is 10-20 min.
Preferably, water is sprayed in the second granulation stage and the amount of water sprayed is 30% to 35% based on the total dry weight of the lime mud and fly ash.
Preferably, siO in the white mud and fly ash 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.5-2:1.
Preferably, the solid NaOH is according to Na of 0.8-1.2:1 2 O/Al 2 O 3 The molar ratio is mixed with the white mud and the fly ash.
Preferably, the aging is carried out at 60-90℃for 4-8 hours.
Preferably, the aging produces an aged product, and the aged product is crystallized in water, the crystallization being performed at 90 to 110 ℃ for 4 to 10 hours.
According to another aspect of the present invention, there is provided a 4A molecular sieve prepared by the above-described method of the present invention.
Aiming at the problems that solid and liquid hazardous wastes are easy to generate in the process of preparing the molecular sieve from the white mud in the prior art, the prepared molecular sieve is powdery rather than granular and cannot be directly used, and the preparation process is complex and high in cost, the problem of generating the solid and liquid hazardous wastes in the process of preparing the molecular sieve from the white mud is solved by selecting specific raw materials and the preparation process, the prepared molecular sieve is granular, and the molecular sieve can be directly applied to the fields of chemical industry, medicine and the like, and meanwhile, the preparation process is simple and the cost is low.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 shows XRD patterns of a 4A molecular sieve obtained according to example 8 of the present invention;
FIG. 2 shows an SEM image of a 4A molecular sieve obtained according to example 8 of the present invention (with magnification of 1.50 KX);
fig. 3 shows an SEM image of a 4A molecular sieve obtained according to example 8 of the present invention (with a magnification of 25.00 KX).
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
The present application is described in further detail below in conjunction with specific embodiments, which should not be construed as limiting the scope of the claims.
As described in the background section of the present application, there are problems in the prior art that solid and liquid hazardous wastes are easily generated in the process of preparing molecular sieves from white mud, the prepared molecular sieves are powdery rather than granular, cannot be directly used, and the preparation process is complex and has high cost. To solve this problem, the present application provides a method for preparing a 4A molecular sieve. The preparation method comprises the steps of sequentially granulating, aging and crystallizing a mixture of white mud, circulating fluidized bed fly ash and solid NaOH to obtain the 4A molecular sieve; wherein the white mud comprises 65 to 75 weight percent of SiO 2 12 to 20 weight percent of Al 2 O 3 0 to 0.2wt% of K 2 O and/or Na 2 O, 0 to 12wt% loss on ignition and the balance impurities (such as CaO, tiO) 2 、MgO、Fe 2 O 3 Etc.); the circulating fluidized bed fly ash comprises 25 to 38 weight percent of SiO 2 40 to 55 weight percent of Al 2 O 3 0 to 0.5wt% of K 2 O and/or Na 2 O, 0 to 7wt% loss on ignition and the balance impurities (such as CaO, mgO, tiO) 2 、Fe 2 O 3 Etc.).
The method reduces the cost of raw materials by selecting low-cost bulk industrial solid waste fly ash and white mud as raw materials, enables the prepared molecular sieve to be granular and can be directly used by performing a granulating step, omits a process for preparing the granular molecular sieve by using the powdery molecular sieve, avoids the problem that powder easily appears in the process blocks the holes of a device, and does not have roasting treatment in the preparation method of the method, thereby further reducing the production cost.
In the present invention, "the mixture of the white clay, the circulating fluidized bed fly ash, and the solid NaOH is granulated, aged, and crystallized in this order" means that the mixture of the white clay, the circulating fluidized bed fly ash, and the solid NaOH is directly granulated, and then aged and crystallized.
In the present invention, "aging" may be standing aging.
In the present invention, the 4A molecular sieve is a self-supporting type 4A molecular sieve.
In a preferred embodiment, the granulation of the present invention is carried out in a granulator; and the granulation comprises a first granulation stage, wherein the stirring speed of the first granulation stage is 3700-4000 r/min, and the stirring time is 10-20 min. The materials are scattered in the first granulating stage and are uniformly mixed, so that the impact of material agglomeration on the strength of the spherical cores is prevented.
In a preferred embodiment, the granulation further comprises a second granulation stage after the first granulation stage, wherein the second granulation stage has a stirring rate of 3300 to 3500r/min and a stirring time of 10 to 20min. A spherical core is formed in the second granulation stage.
In a preferred embodiment, the granulation further comprises a third granulation stage after the second granulation stage, wherein the third granulation stage has a stirring rate of 1500 to 2000r/min and a stirring time of 10 to 20min. The third granulation stage grows the pellets to form the desired granules having a diameter of 1.6-2.5 mm.
Preferably, water is sprayed in the second granulation stage and the amount of water sprayed is 30% to 35% based on the total dry weight of the lime mud and fly ash. Because the mixture of the white mud, the fly ash and the solid NaOH is sprayed into water in the second granulation stage to form spherical cores, no hazardous waste solid is produced in the stage, and the use of a binder is avoided.
The "water addition amount is 30 to 35% of the total dry weight of the white mud and the fly ash" means the weight (water) [ total dry weight (white mud+circulating fluidized bed fly ash) ] x 100%.
To further form a molecular sieve of higher crystallinity and greater compressive strength, in a preferred embodiment, the white mud is combined with SiO in the fly ash 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.5-2:1.
In order to further form higher crystallinity, higher compressive strength molecular sieves, in a preferred embodiment, the solid NaOH is in the range of 0.8 to 1.2:1 Na 2 O/Al 2 O 3 And mixing the white mud and the fly ash in a molar ratio.
The amount of NaOH is Na 2 A meter of O.
In order to strengthen the gel structure and to reduce the production of solid and liquid hazardous waste, in a preferred embodiment, the aging step is carried out at 60-90 ℃ for 4-8 hours.
In a preferred embodiment, the aging produces an aged product, which is crystallized in water at 90-110 ℃ for 4-10 hours, resulting in a higher crystallinity of the 4A molecular sieve produced. According to the method, the aging product obtained by the granulating and aging steps can be crystallized in water without adopting special crystallization solvents (such as common diethyl ether and alcohol solution) so as to obtain the 4A molecular sieve with higher crystallinity, and the preparation raw materials are cleaner and have no liquid hazardous waste.
According to yet another aspect of the present invention, there is provided a 4A molecular sieve prepared by the process of the present invention.
The advantageous effects of the present invention will be further described below with reference to examples.
Characterization of the properties of the 4A molecular sieves:
the crystallinity test method comprises the following steps: special analysis software for crystallinity of D8 ADVANCE Davinci diffractometer, bruce AXS, germany.
The compressive strength testing method comprises the following steps: testing was performed as required by the HG/T2783-2020 standard.
The composition of the white mud used in all examples is shown in table 1 below.
TABLE 1
SiO 2 Al 2 O 3 Na 2 O K 2 O TiO 2 LOI Impurity(s)
Content/wt% 65 20 0.02 0.02 4.3 10.2 0.46
The composition of the fly ash used in all examples is set forth in table 2 below.
TABLE 2
Figure BDA0004150073030000041
Note that: the impurities in tables 1 and 2 are Fe 2 O 3 Etc.
Example 1
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 4000r/min, the stirring time is 10min, the stirring speed of the second granulating stage is 3500r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of the white mud and the fly ash is 612ml, the stirring speed of the third granulating stage is 1500r/min, the stirring time is 20min, and the particles with the diameters ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to obtain a 4A molecular sieve having a crystallinity of 87% and a compressive strength of 35.8N.
Example 2
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 0r/min, the stirring time is 0min, the stirring speed of the second granulating stage is 3500r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of the white mud and the fly ash is 612ml, the stirring speed of the third granulating stage is 1500r/min, the stirring time is 20min, and the particles with the diameters ranging from 1.6mm to 2.5mm are formed. Aging the formed particles at 60deg.C for 8 hr, crystallizing at 90deg.C for 10 hr, and filtering and drying to obtain 4A molecular sieve with 86.7% crystallinity and 30.6N compressive strength。
Example 3
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 3600r/min, the stirring time is 10min, the stirring speed of the second granulating stage is 3500r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of white mud and fly ash is 612ml, the stirring speed of the third granulating stage is 1500r/min, the stirring time is 20min, and the particles with the diameters ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 86.7% and a compressive strength of 32.6N.
Example 4
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 4000r/min, the stirring time is 10min, the stirring speed of the second granulating stage is 3700r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of white mud and fly ash is 612ml, the stirring speed of the third granulating stage is 1500r/min, the stirring time is 20min, and the particles with the diameter less than or equal to 1.6mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to obtain a 4A molecular sieve having a crystallinity of 87.2% and a compressive strength of 9.6N.
Example 5
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 Sum of (2)Molar ratio of 2:1), then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 4000r/min, the stirring time is 10min, the stirring speed of the second granulating stage is 3200r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of white mud and fly ash is 612ml, the stirring speed of the third granulating stage is 1500r/min, and the stirring time is 20min, so that particles with the diameter less than or equal to 0.5mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 87.2% and a compressive strength of 4.7N.
Example 6
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 4000r/min, the stirring time is 10min, the stirring speed of the second granulating stage is 3500r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of the white mud and the fly ash is 612ml, the stirring speed of the third granulating stage is 2200r/min, the stirring time is 20min, and the particles with the diameters ranging from 1.0 mm to 2.0mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 86.9% and a compressive strength of 26.9N.
Example 7
1000g of white clay was mixed with 1040g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) to (1) is then Na according to 0.8:1 2 O/Al 2 O 3 480g of solid NaOH was added in a molar ratio to effect uniform mixing, and the resulting mixture was granulated in a granulator, wherein the stirring rate in the first granulation stage was 4000r/min, while stirringThe stirring speed in the second granulation stage is 3500r/min, the stirring time is 10min, the water spraying amount based on the total dry weight of the white mud and the fly ash is 612ml, the stirring speed in the third granulation stage is 1000r/min, the stirring time is 20min, and the particles with the diameters ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 60℃for 8 hours, then crystallized at 90℃for 10 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 86.7% and a compressive strength of 23.4N.
Example 8
1000g of white clay was mixed with 1320g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.8:1) and then Na according to 1.0:1 2 O/Al 2 O 3 The solid NaOH is added in a molar ratio of 726g for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulation stage is 3700r/min, the stirring time is 20min, the stirring speed of the second granulation stage is 3300r/min, the stirring time is 20min, the water spraying amount based on the total dry weight of the white mud and the circulating fluidized bed fly ash is 812ml, the stirring speed of the third granulation stage is 1500r/min, and the stirring time is 20min, so that the particles with the diameter ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 70℃for 6 hours, then crystallized at 100℃for 8 hours, and then filtered and dried to obtain a 4A molecular sieve having a crystallinity of 92% and a compressive strength of 37.9N.
Figure 1 shows the XRD spectrum of the 4A molecular sieve obtained according to example 8 of the present invention.
Fig. 2 shows an SEM image of a 4A molecular sieve obtained according to example 8 of the present invention (with magnification of 1.50 KX).
Fig. 3 shows an SEM image of a 4A molecular sieve obtained according to example 8 of the present invention (with a magnification of 25.00 KX).
Example 9
1000g of white clay was mixed with 2000g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.5:1) and then Na according to 0.8:1 2 O/Al 2 O 3 816g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 3700r/min, the stirring time is 20min, the stirring speed of the second granulating stage is 3300r/min, the stirring time is 20min, the water spraying amount based on the total dry weight of white mud and fly ash is 1050ml, the stirring speed of the third granulating stage is 1500r/min, the stirring time is 20min, and the particles with the diameter ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 90℃for 4 hours, then crystallized at 110℃for 6 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 87% and a compressive strength of 35.6N.
Example 10
1000g of white mud was mixed with 1500g of circulating fluidized bed fly ash (wherein the white mud was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.7:1) and then Na according to 0.8:1 2 O/Al 2 O 3 640g of solid NaOH is added in a molar ratio for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulating stage is 3700r/min, the stirring time is 20min, the stirring speed of the second granulating stage is 3300r/min, the stirring time is 20min, the water spraying amount based on the total dry weight of white mud and fly ash is 875ml, the stirring speed of the third granulating stage is 1500r/min, and the stirring time is 20min, so that particles with the diameter ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 70℃for 6 hours, then crystallized at 110℃for 4 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 90% and a compressive strength of 36.2N.
Example 11
A4A molecular sieve was prepared in the same manner as in example 8, except that Na was used in a ratio of 1.2:1 2 O/Al 2 O 3 876g of solid NaOH was added in a molar ratio to uniformly mix and form particles having a diameter in the range of 1.6 to 2.5mm, and the molecular sieve obtained had a crystallinity of 87.2% and a compressive strength of 35.1N.
Example 12
A4A molecular sieve was synthesized in the same manner as in example 8, except that the stirring rate in the first pelletization stage was 1000r/min, the stirring rate in the second pelletization stage was 2000r/min, and the stirring rate in the third pelletization stage was 3000r/min, to form < 0.5mm particles, and the obtained molecular sieve had a crystallinity of 86.4% and a compressive strength of 1.5N.
Example 13
A4A molecular sieve was prepared in the same manner as in example 8, except that 1000g of white clay was mixed with 4900g of circulating fluidized bed fly ash (wherein white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (1:1) is then Na according to 1.0:1 2 O/Al 2 O 3 2270g of solid NaOH was added in a molar ratio to uniformly mix to form particles having a diameter in the range of 1.6 to 2.5mm, and the molecular sieve obtained had a crystallinity of 78% and a compressive strength of 13.6N, but sodalite was formed in the molecular sieve.
Example 14
A4A molecular sieve was prepared in the same manner as in example 8, except that 1000g of white clay was mixed with 410g of circulating fluidized bed fly ash (wherein white clay was mixed with SiO in the fly ash 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 3:1), then Na according to 1.0:1 2 O/Al 2 O 3 334g of solid NaOH is added in a molar ratio for uniform mixing to form particles with the diameter ranging from 1.6mm to 2.5mm, the crystallinity of the obtained molecular sieve is 52.4 percent, the compressive strength is 7.5N, and the X-type molecular sieve is formed in the sample.
Example 15
A4A molecular sieve was prepared in the same manner as in example 8, except that 1000g of white clay was mixed with 1320g of circulating fluidized bed fly ash (wherein white clay was mixed with SiO in the fly ash 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.8:1) and then Na according to 0.6:1 2 O/Al 2 O 3 438g of solid NaOH was added to the mixture at a molar ratio to uniformly mix the mixture and form particles having a diameter in the range of 1.6 to 2.5mm, and the molecular sieve obtained had a crystallinity of 33.4% and a compressive strength of 6.5N.
Example 16
In the same way as in example 8The method for preparing the 4A molecular sieve is characterized in that 1000g of white mud is mixed with 1320g of circulating fluidized bed fly ash (wherein the white mud is mixed with SiO in the fly ash 2 Sum of (2) and Al 2 O 3 The molar ratio of the sum of (2) to (1.8:1) is then Na according to 2:1 2 O/Al 2 O 3 1460g of solid NaOH is added in a molar ratio for uniform mixing to form particles with the diameter ranging from 1.6mm to 2.5mm, and the obtained molecular sieve has the crystallinity of 73.6 percent and the compressive strength of 16.9N.
Example 17
1000g of white clay was mixed with 1320g of circulating fluidized bed fly ash (wherein the white clay was mixed with SiO in the fly ash) 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.8:1) and then Na according to 1.0:1 2 O/Al 2 O 3 The solid NaOH is added in a molar ratio of 726g for uniform mixing, and the obtained mixture is granulated in a granulator, wherein the stirring speed of the first granulation stage is 3700r/min, the stirring time is 20min, the stirring speed of the second granulation stage is 3300r/min, the stirring time is 20min, the water spraying amount based on the total dry weight of the white mud and the circulating fluidized bed fly ash is 812ml, the stirring speed of the third granulation stage is 2000r/min, and the stirring time is 10min, so that the particles with the diameter ranging from 1.6mm to 2.5mm are formed. The formed particles were aged at 70℃for 6 hours, then crystallized at 100℃for 8 hours, and then filtered and dried to give a 4A molecular sieve having a crystallinity of 91.8% and a compressive strength of 38.2N.
Table 3 below summarizes the crystallinity and compressive strength results of the 4A molecular sieves prepared according to the examples.
TABLE 3 Table 3
Figure BDA0004150073030000081
Figure BDA0004150073030000091
From the results of examples 1-2, it can be seen that example 1, in which granulation was performed in three stages, had better crystallinity and compressive strength than example 2, in which granulation was performed in two stages; as can be seen from the results of examples 1 and 3 to 7, the stirring rate in the first granulation stage was 3700 to 4000r/min and the stirring time was 10 to 20min; the stirring speed of the second granulation stage is 3300-3500 r/min, and the stirring time is 10-20 min; the stirring rate in the third granulation stage is 1500-2000 r/min, and the stirring time is 10-20 min, compared with examples 3-7, example 1 shows better compressive strength, wherein for example 4, no spherical cores are formed, particles are formed by water bonding agglomeration and collision, the compressive strength is lower, for example 5, no spherical cores are formed, the compressive strength is lower, and the particle size of the 4A molecular sieve obtained in examples 4-5 is smaller; from the results of example 8 and examples 12 to 16, it can be seen that example 8 shows a better compressive strength, and the granulation rate increases inversely for example 12, no granules can be formed, and the silicon aluminum structure is difficult to form with a large alkali content for example 16, mainly comprising sodalite.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method for preparing a 4A molecular sieve, the method comprising: sequentially granulating, aging and crystallizing the mixture of the white mud, the circulating fluidized bed fly ash and the solid NaOH to obtain the 4A molecular sieve; wherein the white mud comprises 65 to 75 weight percent of SiO 2 12 to 20 weight percent of Al 2 O 3 0 to 0.2wt% of K 2 O and/or Na 2 O, 0-12 wt% loss on ignition, and the balance impurities; the circulating fluidized bed fly ash comprises 25-38 wt% of SiO 2 40 to 55 weight percent of Al 2 O 3 0 to 0.5wt% of K 2 O and/or Na 2 O, 0-7wt% of loss on ignition, and the balance of impurities.
2. The method of claim 1, wherein the granulating is performed in a granulator; and the granulation comprises a first granulation stage, wherein the stirring rate of the first granulation stage is 3700-4000 r/min, and the stirring time is 10-20 min.
3. The method according to claim 2, wherein the granulation further comprises a second granulation stage after the first granulation stage, wherein the second granulation stage has a stirring rate of 3300 to 3500r/min and a stirring time of 10 to 20min.
4. A method of preparing according to claim 3, characterized in that the granulation further comprises a third granulation stage after the second granulation stage, wherein the third granulation stage has a stirring rate of 1500-2000 r/min and a stirring time of 10-20 min.
5. The method according to claim 3 or 4, characterized in that water is sprayed in the second granulation stage, and the water spray is 30-35% based on the total dry weight of the lime mud and the fly ash.
6. The method according to any one of claims 1 to 4, wherein the white mud and SiO in the fly ash are as follows 2 Sum of (2) and Al in both 2 O 3 The molar ratio of the sum of (2) is 1.5-2:1.
7. The process according to any one of claims 1 to 4, wherein the solid NaOH is in the form of Na 0.8-1.2:1 2 O/Al 2 O 3 And mixing the white mud and the fly ash in a molar ratio.
8. The preparation process according to any one of claims 1 to 4, wherein the aging is carried out at 60 to 90 ℃ for 4 to 8 hours.
9. The method according to any one of claims 1 to 4, wherein the aging produces an aged product, the aged product is crystallized in water, and the crystallization is performed at 90 to 110 ℃ for 4 to 10 hours.
10. A 4A molecular sieve prepared by the method of any one of claims 1 to 9.
CN202310315193.9A 2023-03-27 2023-03-27 4A molecular sieve and preparation method thereof Pending CN116282064A (en)

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