CN113636569B - Molecular sieve molding without acidity loss and preparation method thereof - Google Patents

Molecular sieve molding without acidity loss and preparation method thereof Download PDF

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CN113636569B
CN113636569B CN202110878040.6A CN202110878040A CN113636569B CN 113636569 B CN113636569 B CN 113636569B CN 202110878040 A CN202110878040 A CN 202110878040A CN 113636569 B CN113636569 B CN 113636569B
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CN113636569A (en
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刘家旭
贺宁
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Dalian University of Technology
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    • 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
    • C01B39/026—After-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
    • 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
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    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7007—Zeolite Beta
    • 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
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    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/38—Base treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/40—Special temperature treatment, i.e. other than just for template removal
    • 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
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/42—Addition of matrix or binder particles

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Abstract

The invention provides a molecular sieve molding without acidity loss and a preparation method thereof, which comprises the steps of mixing semi-crystallized molecular sieve raw powder with a binder, molding, drying, roasting, mixing with mother liquor, organic alkali and an aluminum source which are remained in the synthesized semi-crystallized molecular sieve raw powder, carrying out secondary crystallization, separating, drying and roasting to obtain the molecular sieve molding without acidity loss. The invention fully utilizes a large amount of active hydroxyl on the surface of the semi-crystallized molecular sieve, and because the semi-crystallized molecular sieve is in a semi-crystallized state, a plurality of pore channels are still in an open state, not only can nutrient substances in mother liquor be reused in the secondary crystallization process of the second molding, but also the double functions of etching and structure guiding are achieved due to the addition of organic alkali, and the binder and the aluminum source in the material are introduced into the skeleton growth of the molecular sieve in a secondary crystallization mode. Therefore, the formed molecular sieve prepared by the technology has no acidity loss, the pore canal of the material is smooth, and the existence of the binder is hardly seen.

Description

Molecular sieve molding without acidity loss and preparation method thereof
Technical Field
The invention belongs to the technical field of molecular sieve forming, and particularly relates to a molecular sieve forming object without acidity loss and a preparation method thereof. More particularly relates to a molecular sieve molding without acidity loss and a preparation method thereof, which are applied to the fields of catalytic materials, adsorption separation and the like.
Background
The zeolite molecular sieve has the characteristics of three-dimensional microporous structure, large specific surface area, adjustable acidity, good hydrothermal stability and mechanical stability, and the like, and is widely applied to the fields of catalysis and adsorption separation. Generally, the synthetic molecular sieves are in powder form, and the powder molecular sieves are not directly industrially applicable. Thus, molecular sieve molding gives materials with certain shape and mechanical strength, which are indispensable procedures for molecular sieve industrial application. However, during the molding process, a certain amount of binder is required. The common binders are usually weak acids or inert materials without acidity such as amorphous aluminum oxide, silicon oxide, kaolin, amorphous silicon aluminum, and the like. The addition of the catalyst reduces the content of the effective components of the molecular sieve, and can block the pore opening of the molecular sieve to influence the diffusion of reactants and products; has obvious influence on the performances of the catalyst, such as texture, mechanical strength, activity, acidity, service life and the like.
To solve this problem, binder-free shaped molecular sieves have emerged, namely: the molecular sieve molding contains little or no inert binder. For example, the method is that ZSM-5 powder and a binder containing silicon dioxide are mixed, molded and dried, and then the mixture is crystallized and roasted in organic amine or organic quaternary ammonium alkaline water solution or steam to obtain the product. Chinese patent CN103030156a, the process mixes ZSM-5 molecular sieve powder with amorphous silica binder; drying and then treating with water vapor or vapor containing inorganic ammonia to obtain the non-adhesive ZSM-5 molecular sieve. Chinese patent CN107512729a, the process mixes ZSM-5 molecular sieve with binder, pore-forming agent and aqueous acid solution, forming, drying to obtain ZSM-5 molecular sieve precursor; crystallizing a mixture of the ZSM-5 molecular sieve precursor, a second silicon source, a second aluminum source, an alkali source, an organic template agent and water, separating and drying a solid product, and finally obtaining the non-adhesive ZSM-5 molecular sieve catalyst; the method solves the problems of long secondary crystallization time, incomplete crystallization and poor catalytic performance in the preparation process of the binderless ZSM 5 molecular sieve catalyst.
Although the binderless molecular sieve can be obtained in the prior art, the pore canal is dredged by removing or converting the binder, and the problem of blocking the pore canal of the binder is well solved. However, the prepared non-binder molecular sieves need to be prepared into completely crystallized molecular sieve raw powder, and then mixed with a binder for molding and then crystallized. The acidity of the material is reduced compared with that of the original powder, namely, the material does not play a role in recovering or increasing the active center. Therefore, when the non-adhesive molded molecular sieve is prepared, how to ensure that the acid active center is not lost and the pore canal of the material is smooth is a great challenge for preparing the non-adhesive molded molecular sieve.
Disclosure of Invention
The invention provides a molecular sieve molding product without acidity loss and a preparation method thereof, which are used for solving the problem that the acidity of a molecular sieve and the smoothness of a pore canal of a material are reduced due to the existing molding. The invention takes semi-crystallized molecular sieve powder as raw material, and is formed by kneading with a binder. And then, the mother solution of the previous crystallization is utilized, and organic alkali and an additional aluminum source are added in the mother solution, so that the acid of the formed molecular sieve is obviously recovered (compared with the completely crystallized molecular sieve raw powder) while the binder is converted due to the fact that a large amount of surface hydroxyl bases of the semi-crystallized molecular sieve are easy to combine with the additional aluminum source, which is incomparable with the non-binder formed molecular sieve prepared by the prior art. The method has the advantages that the method shortens the synthesis time of the molecular sieve raw powder and the conversion time of the molding molecular sieve binder, makes full use of the mother liquor of molecular sieve synthesis, ensures that the mechanical strength of the obtained molding molecular sieve meets industrial production, and ensures that the acidity of the prepared molding molecular sieve is equivalent to that of the full-crystallized powdery molecular sieve, and ensures the smoothness of pore channels of molding materials due to the conversion of the binder.
The technical scheme of the invention is as follows:
a preparation method of a molecular sieve molding without acidity loss comprises the following steps:
s1, synthesizing semi-crystalline molecular sieve raw powder;
s2, uniformly mixing the semi-crystallized molecular sieve raw powder with a binder, extruding, forming and roasting to obtain a molecular sieve formed product containing the binder;
and S3, mixing the molecular sieve molding containing the binder with the organic alkali, the aluminum source and the mother solution reserved in the step S1 to obtain a mixed solution, performing secondary crystallization in an autoclave, separating and roasting a solid product after crystallization to obtain the molecular sieve molding without acidity loss.
In the step S1, the semi-crystallized molecular sieve raw powder is semi-crystallized ZSM-5 or Beta molecular sieve raw powder.
In the step S1, the semi-crystallization state ZSM-5 molecular sieve raw powder is synthesized according to the published literature 'catalytic journal, 32,1702-1711':
(1) Uniformly mixing sodium silicate, sodium hydroxide and water under intense stirring to prepare initial raw material silicon, and fully stirring for 1 hour;
(2) Under the intense stirring, uniformly mixing aluminum sulfate, sulfuric acid and water to prepare initial raw material aluminum, and fully stirring for 1 hour;
(3) Slowly dripping the completely dissolved raw material aluminum solution into the raw material silicon solution, stirring for 4-10 hours at room temperature, wherein the molar composition of the synthetic solution is as follows: 18Na 2 O:100SiO 2 :0.5～4Al 2 O 3 :12SO 4 2- :4000H 2 O；
(4) Filling the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature and time; the crystallization temperature is 130-190 ℃, and the hydrothermal crystallization time is 5 minutes-28 hours;
(5) The semi-crystallized ZSM-5 solid is obtained and is filtered, dried and roasted, and the obtained mother liquor is reserved (used in the step S3 of the invention); the drying temperature is 110 ℃, and the drying time is 8 hours; the roasting temperature is 500 ℃ and the roasting time is 10 hours.
In the step S1, the semi-crystallization state Beta molecular sieve raw powder is prepared according to the structure guiding effect research [ D ] of Beta zeolite seed crystal of publication' Zheng Bumei, and the following steps: university of company, university of worker, 2014 "synthesis:
(1) Uniformly mixing white carbon black, sodium hydroxide and water under intense stirring to prepare initial raw material silicon, and fully stirring for 1 hour;
(2) Slowly adding sodium metaaluminate into the liquid under intense stirring, adding 10wt.% Beta seed crystal, continuing intense stirring for 1 hour, and then carrying out high-speed shearing and emulsifying treatment for 10 minutes by adopting a shearing and emulsifying machine;
the molar composition of the synthetic solution is as follows: 8.9 to 16.4Na 2 O:30～60SiO 2 :1Al 2 O 3 :480～960H 2 O；
(3) Filling the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature and time; the crystallization temperature is 100-150 ℃, and the hydrothermal crystallization time is 5 minutes-18 hours;
(4) The semi-crystallized Beta solid is obtained and is filtered, dried and roasted, and the obtained mother liquor is reserved (used in the step S3 of the invention); the drying temperature is 110 ℃, and the drying time is 8 hours; the roasting temperature is 500 ℃ and the roasting time is 10 hours.
The binder in S2 is at least one selected from silica sol, silica gel, silica powder and solid silica gel; the mass ratio of the semi-crystalline molecular sieve raw powder to the binder is 1:1-9:1.
The organic base in S3 is at least one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, n-butylamine solution and ethylenediamine.
The aluminum source is at least one of aluminum oxide, aluminum nitrate, sodium metaaluminate and aluminum isopropoxide.
The mass ratio of the mother liquor, the organic alkali, the aluminum source (alumina) and the molecular sieve molding containing the binder in the S3 mixed solution is 10-50:0-1.5:0.01-0.05:5.
The conditions of the secondary crystallization are as follows: the temperature is 100-200 ℃ and the time is 5 minutes-50 hours.
The mother liquor in S3 is replaced by water or the original synthetic liquor in S1.
The method fully utilizes a large amount of active hydroxyl on the surface of the first-step semi-crystallized molecular sieve, and because the active hydroxyl is in a semi-crystallized state, a plurality of pore channels are still in an open state, not only can nutrient substances in mother liquor be reused in the secondary crystallization process of the second-time formed product, but also the double functions of etching and structure guiding are achieved due to the addition of organic alkali, and the binder in the material and an aluminum source are introduced into the skeleton growth of the molecular sieve in a secondary crystallization mode. Therefore, the formed molecular sieve prepared by the technology has no acidity loss, the pore canal of the material is smooth, and the existence of the binder is hardly seen.
The invention also provides a molecular sieve molding without acidity loss prepared by the method.
Compared with the prior art, the invention has the following beneficial effects:
the traditional molecular sieve forming technology reduces the content of active components of the molecular sieve due to the addition of the binder, and can block the pore opening of the molecular sieve, so that the texture, mechanical strength, activity, acidity, service life and other properties of the molecular sieve are obviously affected. The invention takes semi-crystallized molecular sieve raw powder as raw material, and the raw material is kneaded with a binder to form, then the synthetic mother liquor is fully utilized, organic alkali and aluminum source are added, and the added aluminum source and unreacted nutrient substances in the mother liquor can be combined with a large amount of active hydroxyl groups on the surface of the semi-crystallized molecular sieve, so that the acidity of the binder is obviously recovered while the binder is converted. The formed molecular sieve prepared by the method not only converts the binder and ensures the smoothness of pore channels of the material, but also has mechanical strength meeting the industrial production, and compared with the acidity of the full-crystallized powdery molecular sieve, the formed molecular sieve has no acidity loss.
Drawings
FIG. 1 is an XRD spectrum of comparative example D1# powder, D1# molded and example sample 1#.
FIG. 2 shows TEM characterization results of comparative example D1# powder, D1# molding, and example sample 1#.
Detailed Description
Comparative example 1
0.75g NaOH was weighed into 50g sodium Silicate (SiO) 2 Mass fraction 60%, na 2 O mass fraction 10%), stirring uniformly with a magnetic stirrer; 4.28g of aluminum sulfate was then completely dissolved in 5g of water, and 2.25g of concentrated sulfuric acid (98%) was slowly added; slowly dripping the completely dissolved aluminum sulfate solution into the solution containing sodium silicate, stirring at room temperature for 6 hours, wherein the molar composition of the synthetic solution is as follows: 18Na 2 O:100SiO 2 :2.5Al 2 O 3 :12SO 4 2- :4000H 2 O; putting the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature to 190 ℃ and the hydrothermal crystallization time to 16 hours; filtering, drying at 110 ℃ for 8 hours, and roasting at 500 ℃ for 10 hours to obtain ZSM-5 raw powder with complete crystallization, which is named as D1# powder. Taking 20 g of D1# powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Air atmosphere at 540 DEG CRoasting for 5 hours. The obtained product was designated as sample D1# molding.
Comparative example 2
Uniformly mixing 60g of white carbon black, 21.6g of sodium hydroxide and 32g of water, slowly adding 4.9g of sodium metaaluminate under intense stirring, adding 10wt.% Beta seed crystal (6.5 g), continuously and vigorously stirring for 1 hour, and then carrying out high-speed shearing and emulsifying treatment for 10 minutes by adopting a shearing emulsifying machine; the molar composition of the synthetic solution is as follows: 8.9Na 2 O:30SiO 2 :1Al 2 O 3 :960H 2 O; filling the obtained sol into an autoclave lined with polytetrafluoroethylene, wherein the crystallization temperature is 150 ℃, and the hydrothermal crystallization time is 48 hours; filtering, drying at 110 ℃ for 8 hours, and roasting at 500 ℃ for 10 hours to obtain Beta raw powder with complete crystallization, which is named as D2# powder. Taking 20 g of D2# powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃. The obtained product was designated as sample D2# molded.
Example 1
The first step: 0.75g NaOH was weighed into 50g sodium Silicate (SiO) 2 Mass fraction 60%, na 2 O mass fraction 10%), stirring uniformly with a magnetic stirrer; 4.28g of aluminum sulfate was then completely dissolved in 5g of water, and 2.25g of concentrated sulfuric acid (98%) was slowly added; slowly dripping the completely dissolved aluminum sulfate solution into the solution containing sodium silicate, stirring at room temperature for 6 hours, wherein the molar composition of the synthetic solution is as follows: 18Na 2 O:100SiO 2 :2.5Al 2 O 3 :12SO 4 2- :4000H 2 O; putting the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature to 135 ℃ and the hydrothermal crystallization time to 15 hours; the obtained semi-crystallized ZSM-5 solid is filtered, dried for 8 hours at 110 ℃ and roasted for 10 hours at 500 ℃ to obtain semi-crystallized ZSM-5 powder (raw powder), and the synthesized mother solution is reserved for subsequent molding.
And a second step of: taking 20 g of semi-crystallized ZSM-5 powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃ to obtain a semi-crystallized ZSM-5 shaped product containing the binder.
And a third step of: preparing 25g of mother liquor into tetrapropylammonium hydroxide alkali solution with the mass fraction of 0.6%, placing the tetrapropylammonium hydroxide alkali solution in a reaction kettle, adding 0.03g of aluminum oxide into the reaction kettle, adding 5g of the formed product of the semi-crystallized ZSM-5 containing the binder prepared in the second step into the reaction kettle, shaking the mixture uniformly, standing the mixture for 10 minutes, placing the reaction kettle into a baking oven at 170 ℃ for reaction for 24 hours, separating a solid product after the reaction is finished, washing the solid product to be neutral by deionized water, drying the solid product, and roasting the solid product in an air atmosphere at 540 ℃ for 5 hours. The resulting product was designated sample # 1.
Example 2
The first step: 0.75g NaOH was weighed into 50g sodium Silicate (SiO) 2 Mass fraction 60%, na 2 O mass fraction 10%), stirring uniformly with a magnetic stirrer; 4.28g of aluminum sulfate was then completely dissolved in 5g of water, and 2.25g of concentrated sulfuric acid (98%) was slowly added; slowly dripping the completely dissolved aluminum sulfate solution into the solution containing sodium silicate, stirring at room temperature for 6 hours, wherein the molar composition of the synthetic solution is as follows: 18Na 2 O:100SiO 2 :2.5Al 2 O 3 :12SO 4 2- :4000H 2 O; putting the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature to 135 ℃ and the hydrothermal crystallization time to 15 hours; the obtained semi-crystallized ZSM-5 solid is filtered, dried for 8 hours at 110 ℃ and roasted for 10 hours at 500 ℃ to obtain semi-crystallized ZSM-5 powder, and the synthetic mother solution is reserved for subsequent molding.
And a second step of: taking 20 g of semi-crystallized ZSM-5 powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃ to obtain a semi-crystallized ZSM-5 shaped product containing the binder.
And a third step of: preparing 25g of mother liquor into tetrapropylammonium hydroxide alkali solution with the mass fraction of 2.5%, placing the tetrapropylammonium hydroxide alkali solution in a reaction kettle, adding 0.03g of aluminum oxide into the reaction kettle, adding 5g of the formed product containing the binder semi-crystallized ZSM-5 prepared in the second step into the reaction kettle, shaking the mixture uniformly, standing the mixture for 10 minutes, placing the reaction kettle into a baking oven with the temperature of 170 ℃ for reaction for 24 hours, separating a solid product after the reaction is finished, washing the solid product to be neutral by deionized water, drying the solid product, and roasting the solid product in the air atmosphere with the temperature of 540 ℃ for 5 hours. The resulting product was designated sample # 2.
Example 3
The first step: 0.75g NaOH was weighed into 50g sodium Silicate (SiO) 2 Mass fraction 60%, na 2 O mass fraction 10%), stirring uniformly with a magnetic stirrer; 4.28g of aluminum sulfate was then completely dissolved in 5g of water, and 2.25g of concentrated sulfuric acid (98%) was slowly added; slowly dripping the completely dissolved aluminum sulfate solution into the solution containing sodium silicate, stirring at room temperature for 6 hours, wherein the molar composition of the synthetic solution is as follows: 18Na 2 O:100SiO 2 :2.5Al 2 O 3 :12SO 4 2- :4000H 2 O; filling the obtained sol into an autoclave lined with polytetrafluoroethylene, and controlling the hydrothermal crystallization temperature to 150 ℃ and the hydrothermal crystallization time to 8 hours; the obtained semi-crystallized ZSM-5 solid is filtered, dried for 8 hours at 110 ℃ and roasted for 10 hours at 500 ℃ to obtain semi-crystallized ZSM-5 powder, and the synthetic mother solution is reserved for subsequent molding.
And a second step of: taking 20 g of semi-crystallized ZSM-5 powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃ to obtain a semi-crystallized ZSM-5 shaped product containing the binder.
And a third step of: preparing 25g of mother liquor into tetrapropylammonium hydroxide alkali solution with the mass fraction of 2.1%, placing the tetrapropylammonium hydroxide alkali solution in a reaction kettle, adding 0.12g of aluminum nitrate into the reaction kettle, adding 5g of the formed product of the semi-crystallized ZSM-5 containing the binder prepared in the second step into the reaction kettle, shaking the mixture uniformly, standing the mixture for 10 minutes, placing the reaction kettle into a baking oven with the temperature of 200 ℃ for reacting for 18 hours, separating a solid product after the reaction is finished, washing the solid product to be neutral by deionized water, drying the solid product, and roasting the solid product in the air atmosphere with the temperature of 540 ℃ for 5 hours. The resulting product was designated sample 3#.
Examples 4 to 5
The procedure was as in example 3, except that the aluminum source and quality were changed and the other procedures were the same.
Examples numbering Sample numbering Type of aluminum source Aluminum source mass
Example 4 4# NaAlO 2 0.06g
Example 5 5# C 9 H 21 AlO 3 0.2g
Example 6
The first step: uniformly mixing 60g of white carbon black, 21.6g of sodium hydroxide and 32g of water, slowly adding 4.9g of sodium metaaluminate under intense stirring, adding 10wt.% Beta seed crystal (6.5 g), continuously and vigorously stirring for 1 hour, and then carrying out high-speed shearing and emulsifying treatment for 10 minutes by adopting a shearing emulsifying machine; the molar composition of the synthetic solution is as follows: 8.9Na 2 O:30SiO 2 :1Al 2 O 3 :960H 2 O; filling the obtained sol into an autoclave lined with polytetrafluoroethylene, wherein the crystallization temperature is 140 ℃, and the hydrothermal crystallization time is 32 hours; filtering, drying at 110 ℃ for 8 hours, and roasting at 500 ℃ for 10 hours to obtain Beta powder in a semi-crystallization state, wherein the synthesized mother liquor is reserved for subsequent molding.
And a second step of: taking 20 g of semi-crystallized Beta powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃ to obtain a semi-crystallized Beta molding containing the binder.
And a third step of: preparing 25g of mother liquor into tetraethylammonium hydroxide alkali solution with the mass fraction of 2.1%, placing the tetraethylammonium hydroxide alkali solution into a reaction kettle, adding 0.03g of aluminum oxide into the reaction kettle, adding 5g of the semi-crystallized Beta-shaped product containing the binder prepared in the second step into the reaction kettle, shaking the mixture uniformly, standing the mixture for 10 minutes, placing the reaction kettle into a baking oven with the temperature of 150 ℃ for reaction for 24 hours, separating a solid product after the reaction, washing the solid product to be neutral by deionized water, drying the solid product, and roasting the solid product in the air atmosphere with the temperature of 540 ℃ for 5 hours. The resulting product was designated sample 6#.
Example 7
The first step: uniformly mixing 60g of white carbon black, 21.6g of sodium hydroxide and 32g of water, slowly adding 4.9g of sodium metaaluminate under intense stirring, adding 10wt.% Beta seed crystal (6.5 g), continuously and vigorously stirring for 1 hour, and then carrying out high-speed shearing and emulsifying treatment for 10 minutes by adopting a shearing emulsifying machine; the molar composition of the synthetic solution is as follows: 8.9Na 2 O:30SiO 2 :1Al 2 O 3 :960H 2 O; filling the obtained sol into an autoclave lined with polytetrafluoroethylene, wherein the crystallization temperature is 140 ℃, and the hydrothermal crystallization time is 32 hours; filtering, drying at 110 ℃ for 8 hours, and roasting at 500 ℃ for 10 hours to obtain Beta powder in a semi-crystallization state, wherein the synthesized mother liquor is reserved for subsequent molding.
And a second step of: taking 20 g of semi-crystallized Beta powder, adding 17 g of 30wt% silica sol, uniformly mixing, extruding to form strips, and drying at 110 ℃. Roasting for 5 hours in an air atmosphere at 540 ℃ to obtain a semi-crystallized Beta molding containing the binder.
And a third step of: preparing 25g of mother liquor into tetraethylammonium hydroxide alkali solution with the mass fraction of 3.8%, placing the tetraethylammonium hydroxide alkali solution into a reaction kettle, adding 0.02g of aluminum oxide into the reaction kettle, adding 5g of the semi-crystallized Beta-shaped product containing the binder prepared in the second step into the reaction kettle, shaking the mixture uniformly, standing the mixture for 10 minutes, placing the reaction kettle into a baking oven with the temperature of 170 ℃ for reacting for 18 hours, separating a solid product after the reaction, washing the solid product to be neutral by deionized water, drying the solid product, and roasting the solid product for 5 hours in an air atmosphere with the temperature of 540 ℃. The resulting product was designated sample # 7.
Examples 8 to 9
The procedure was as in example 7, except that the aluminum source and quality were changed and the other procedures were the same.
Examples numbering Sample numbering Type of aluminum source Aluminum source mass
Example 8 8# NaAlO 2 0.024g
Example 9 9# C 9 H 21 AlO 3 0.08g
Example 10
XRD characterization is carried out on the samples prepared in the examples, taking comparative example D1# powder, D1# molding and example sample 1# as examples, and XRD spectrograms of the samples are shown in figure 1; comparative example D1# powder, D1# molded and example samples 1-5# relative crystallinity data are shown in Table 1. The results show that all samples are according with ZSM-5 structural features by XRD analysis, i.e. the obtained solid samples are ZSM-5 molecular sieves. XRD data results show that comparative example d1# shows a significant decrease in relative crystallinity compared to other samples due to the low molecular sieve content in the molding material caused by the introduction of the binder. However, the relative crystallinity of the molded sample prepared by the technology is recovered, which indicates that the alkali treatment after the molding of the semi-crystallized molecular sieve powder can convert the binder to generate a secondary crystallization phenomenon.
TABLE 1
Sample numbering Relative crystallinity
D1# powder 100％
D1# shaping 76％
1# 98％
2# 101％
3# 97％
4# 98％
5# 98％
Example 11
The samples prepared in the above examples were subjected to TEM characterization, taking comparative example D1# powder, D1# molding and example sample 1# as examples, and the TEM results are shown in FIG. 2. The results show that the comparative example D1# molding clearly presents two phases, binder and molecular sieve. However, the molded sample prepared by the present technique, sample # 1 from example 1, had very good fusion of the binder and molecular sieve, with the binder substantially disappearing.
Example 12
NH was performed on the samples prepared in the above examples 3 Calibration of the amount of TPD acid, acid distribution of comparative example D1# powder, D1# molding and example samples 1-5# are shown in Table 2. The results show that the comparative example D1# molding not only results in a decrease in the amount of effective molecular sieve due to the introduction of the binder, but also blocks the pores of the molecular sieve, and thus the decrease in acidity is remarkable. However, the acidity of the molded sample prepared by the technology, namely sample No. 1-5, is obviously recovered after the aluminum is supplemented by alkali treatment.
TABLE 2
Example 13
For Beta series samples, namely: d2# powder, d2# molded and example samples 6-9# were characterized by the same analysis, which had the same effect as the ZSM-5 series.

Claims (7)

1. A preparation method of a molecular sieve molding without acidity loss is characterized by comprising the following steps: the method comprises the following steps:
s1, synthesizing semi-crystalline molecular sieve raw powder;
s2, uniformly mixing the semi-crystallized molecular sieve raw powder with a binder, extruding, forming, drying and roasting to obtain a molecular sieve formed product containing the binder;
s3, mixing the molecular sieve molding containing the binder with the organic alkali, the aluminum source and the mother solution reserved in the S1 to obtain a mixed solution, performing secondary crystallization in an autoclave, separating, drying and roasting a solid product after crystallization to obtain a molecular sieve molding without acidity loss; the semi-crystalline state molecular sieve raw powder is semi-crystalline state ZSM-5 or Beta molecular sieve raw powder; the binder is at least one selected from the group consisting of silica sol, silica gel, silica powder and solid silica gel.
2. The method for producing a molecular sieve molded article free from acidity loss as claimed in claim 1, characterized by: the mass ratio of the semi-crystalline molecular sieve raw powder to the binder is 1:1-9:1.
3. The method for producing a molecular sieve molded article free from acidity loss as claimed in claim 1, characterized by: the organic base in S3 is at least one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, n-butylamine solution and ethylenediamine.
4. The method for producing a molecular sieve molded article free from acidity loss as claimed in claim 1, characterized by: the aluminum source in the step S3 is at least one of aluminum oxide, aluminum nitrate, sodium metaaluminate and aluminum isopropoxide.
5. The method for producing a molecular sieve molded article free from acidity loss as claimed in claim 1, characterized by: the conditions for the secondary crystallization in S3 are as follows: the temperature is 100-200 ℃ and the time is 5 minutes-50 hours.
6. The method for producing a molecular sieve molded article free from acidity loss as claimed in claim 1, characterized by: the mother liquor in S3 is replaced by water or the original synthetic liquor in S1.
7. A molecular sieve shaped article without acidity loss, characterized in that: obtained by the process of claim 1.
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