CN117566757A - Low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve and preparation method and application thereof - Google Patents

Low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve and preparation method and application thereof Download PDF

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CN117566757A
CN117566757A CN202311566611.8A CN202311566611A CN117566757A CN 117566757 A CN117566757 A CN 117566757A CN 202311566611 A CN202311566611 A CN 202311566611A CN 117566757 A CN117566757 A CN 117566757A
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molecular sieve
ssz
loess
silicon
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王玉峰
胡浩斌
张腊腊
宋娅丽
王艳艳
许宇辉
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Longdong University
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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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
    • B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
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    • B01J29/763—CHA-type, e.g. Chabazite, LZ-218
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
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Abstract

The invention provides a low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve, and a preparation method and application thereof. The method specifically comprises the following steps: takes loess as raw material, after activation treatment, only silicon source, template agent and water are added for blending, after aging, crystallization and ion exchange, the multilevel porous high silicon molecule with micropore-mesopore coexistence is obtained by calcinationScreen SSZ-13; the prepared high-silicon hierarchical pore molecular sieve SSZ-13 is in a spindle body gathered honeycomb structure, and the specific surface area is 425.3-486.19 m 2 Per gram, the pore size distribution range is 0.4925-51.4956 nm, and the pore volume distribution range is 0.0833-0.1810 cm 3 And/g, the average particle size is 4.814-5.589 μm. The microstructure of the obtained clay-based molecular sieve SSZ-13 has micropores-mesopores coexisting with multistage pores, and the clay-based molecular sieve SSZ-13 can be used as a catalyst to obviously improve the effect of the reaction of preparing olefin from methanol, in particular to improve the selectivity of propylene. In addition, the loess-based molecular sieve SSZ-13 has high silicon-aluminum ratio and contains a small amount of Fe 3+ The ion and the components of the molecular sieve SSZ-13 can also greatly improve the carbon deposition resistance and the catalytic activity of the molecular sieve SSZ-13 in the aspect of preparing propylene from methanol.

Description

Low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve and preparation method and application thereof
Technical Field
The invention belongs to the technical field of loess-based molecular sieve synthesis, and particularly relates to a high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve, and a preparation method and application thereof.
Background
Molecular sieves, also known as zeolites, are porous crystalline materials of aluminosilicates or aluminophosphates having an inorganic framework. The chemical general formula is (M' 2 M)O·Al 2 O 3 ·xSiO 2 ·yH 2 O, wherein M', M are each a monovalent or divalent cation, e.g. K + 、Na + And Ca 2+ 、Ba 2+ Etc. Because of the unique pore channel structure inside, the molecular sieve has excellent catalysis, ion exchange, selective adsorption, anti-fouling and other properties, and is widely applied to the industrial processes of adsorption separation, washing, catalysis and other industrial processes and the field of high-tech materials.
Molecular sieve SSZ-13 is an important industrial catalyst, and has the shape of microporous diamond zeolite with a cube structure, and from the viewpoint of a synthesis method, the molecular sieve SSZ-13 mainly comprises a hydrothermal method, a solid-phase grinding method, a dry gel conversion method, a crystal transformation method, an ultrasonic, microwave or crystal seed added auxiliary synthesis method and the like. At present, the molecular sieve SSZ-13 is synthesized by using N, N, N-trimethyl-1-adamantane ammonium hydroxide as a template agent and adopting a silicon source and an aluminum source of chemical reagents as a framework. However, the use of SSZ-13 is limited due to its expensive templating agent and cost. Meanwhile, the molecular sieve SSZ-13 has the defects of poor carbon deposition resistance, low propylene selectivity and the like when being used in the reaction of preparing olefin or propylene from methanol, and the industrial application of the molecular sieve SSZ-13 is limited.
In the prior art, the research on molecular sieve SSZ-13 comprises the following steps: patent 201910955427.X discloses a preparation method of an olefin catalyst, which synthesizes molecular sieve SSZ-13 by adopting a chemical reagent method, and evaluates the catalytic performance of the molecular sieve SSZ-13 in a methanol-to-olefin reaction by using a fixed bed, and the result shows that the mass selectivity of ethylene and propylene in pyrolysis gas is only about 35% and 46%, and the relatively high specific surface area of the molecular sieve leads to relatively poor carbon deposition resistance of the molecular sieve. Patent 201710161214.0 discloses a hierarchical pore SSZ-13 molecular sieve catalyst, and a synthesis method and application thereof. The method selects long-chain silane as an auxiliary agent for crystallization synthesis reaction, prepares the mole ratio of an alkali source, a silicon source, an aluminum source, a template agent, the long-chain silane and water, and adopts a sectional dynamic/static crystallization mode to obtain the high-crystallinity hierarchical pore SSZ-13 molecular sieve with orderly distributed micropores and mesopores. However, the method adopts a chemical reagent method to synthesize the porous molecular sieve SSZ-13, the synthesis cost is high, and meanwhile, an organic polymer material is also required to be added as an auxiliary agent, so that the environment is polluted, and the synthesis cost is increased. 202110698018.3 discloses a method for synthesizing SSZ-13 molecular sieves using diatomaceous earth as a silicon source. Because the diatomite contains Fe element, the diatomite can be directly introduced into the SSZ-13 molecular sieve in the crystallization process, so that the molecular sieve SSZ-13 has good high-temperature catalytic activity. However, the diatomite raw material used in the method is limited in reserve as a mineral product, and cannot be used for mass production of molecular sieves in northwest China.
In summary, the synthesis methods of molecular sieve SSZ-13 disclosed in the prior art all have the problems of high synthesis cost, incapability of large-scale production, environmental pollution and the like. Moreover, the problems mentioned above also affect the effect of molecular sieve SSZ-13 in the reaction of preparing olefins from methanol, such as poor anti-carbon deposition performance and low yields of ethylene and propylene.
Therefore, obtaining an SSZ-13 molecular sieve with excellent catalytic performance in a methanol-to-olefin reaction by a cheap and green synthesis method is a technical problem to be solved urgently by the technicians in the field.
Disclosure of Invention
The invention aims to provide a low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve. The invention takes loess produced in northwest China as a raw material, and can replace the chemical reagent raw material of the prior molecular sieve SSZ-13 by the processes of purification, acidification, alkalization, low-temperature hydrothermal crystallization and the like, and the low-cost high-silicon multistage pore molecular sieve SSZ-13 can be obtained after aging time and reaction time are controlled, ion exchange and calcination are carried out. The scheme of the invention only needs loess component, does not need to add an aluminum source, and has the advantages of simple steps, mild conditions, low cost, environmental friendliness and the like. The preparation method is simple and easy to implement, has wide and sufficient raw material sources, is particularly suitable for large-scale industrial production and preparation, can truly realize the recycling of loess, and can alleviate the problems of loess high-raw soil and ecological weakness and the like.
In order to achieve the above purpose, the invention provides a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve, which takes loess as a raw material, and only needs to be added with a silicon source, a template agent and water for blending after activation treatment, and the multistage high-silicon loess-based molecular sieve SSZ-13 with micropores-mesopores coexisting is obtained after aging, crystallization and ion exchange and calcination; the high-silicon hierarchical pore molecular sieve SSZ-13 is in a spindle body aggregation honeycomb structure, and the specific surface area is 425.3-486.19 m 2 Per gram, the pore size distribution range is 0.4925-51.4956 nm, and the pore volume distribution range is 0.0833-0.1810 cm 3 And/g, the average particle size is 4.814-5.589 μm.
In order to achieve the above purpose, the invention provides a preparation method of a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve, which specifically comprises the following steps:
s1, purifying: taking loess in northwest area as raw material, washing with water, and drying to obtain purified loess;
s2, acidizing: adding an acidulant into the product of the step, and performing an acidification reaction to obtain acidified loess;
s3, alkalizing: mixing the product of the step with an alkalizing agent, and calcining to obtain alkalized loess;
s4, crystallizing: adding a silicon source, a template agent and water into the product of the last step to lead the mole ratio of raw materials in the system to be SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, resulting in a formulated slurry; aging the prepared slurry at room temperature, and performing crystallization reaction under certain conditions to obtain an unactivated loess-based SSZ-13 molecular sieve;
s5 activated Huang Tuji SSZ-13 molecular sieves: combining unactivated loess-based molecular sieve SSZ-13 with NH 4 And (3) mixing Cl solutions to perform ion exchange reaction, filtering, collecting filter cakes, washing and calcining to obtain the active high-silicon multistage Kong Huangtu-based molecular sieve SSZ-13.
In a preferred embodiment, in the S1 purifying step, the molar ratio of silicon to aluminum in the loess is SiO 2 ∶Al 2 O 3 ＝(6.1～8.5)∶1。
In a preferred embodiment, in the step of S1 purification, the washing and drying conditions are any means known to those skilled in the art, as long as impurities can be removed, preferably, deionized water is used for washing, and 200 mesh sieve is used for filtering, and after repeating 3-5 times, the mixture is dried at 100-120 ℃ for 1-5 hours.
In a preferred embodiment, in the S2 acidification step, the acidulant comprises HCl, H 2 SO 4 、HNO 3 One or more of (a) and (b); the mass concentration of the acidulant is 10-30%, preferably 15-25%.
In a preferred embodiment, in the step of S2 acidification, the solid-to-liquid ratio of the acidulant to the purified loess is 1: (3-6), and preferably, the solid-to-liquid ratio of the acidulant to the purified loess is 1:4.
In a preferred embodiment, in the S2 acidification step, the acidification reaction conditions are: the reaction is stirred at 70-90 ℃ for 1-10 h, preferably at 80-85 ℃ for 4-8 h.
In a preferred embodiment, in the step of S2 acidification, after the acidification reaction is completed, washing with deionized water, filtering, and drying the filter residue to obtain the acidified loess.
The invention acidizes loess, which aims to: loess is a relatively complex silicate structure, its chemical composition removes SiO 2 、Al 2 O 3 In addition, also contains Fe 2 O 3 、CaO、MgO、TiO 2 And the like; therefore, most of CaO, mgO, tiO can be removed from the loess after acid treatment 2 The impurities are equal, and the whiteness of the molecular sieve SSZ-13 product based on the clay is increased; in order to modify molecular sieve SSZ-13, the acidification step requires control of the acidification time and temperature in order to retain a portion of the Fe ions in the catalyst for improved performance of the subsequent catalyst. Meanwhile, in order to prepare the high-silicon molecular sieve SSZ-13, the redundant Al must be dissolved out by acid 2 O 3 The method comprises the steps of carrying out a first treatment on the surface of the Acidification can damage the crystal structure of the loess layer and remove most of aluminum in loess; however, since a part of aluminum atoms are wrapped in the silicate crystal structure and cannot be completely dissolved out, a silicon source needs to be supplemented in the subsequent crystallization step to improve the silicon-aluminum ratio in the crystallization raw material.
In a preferred embodiment, in the step of S3 alkalizing, the alkalizing agent is one or more of NaOH, KOH, liOH; preferably, the alkalizing agent is NaOH solid powder.
In a preferred embodiment, in the S3 alkalizing step, the mass ratio of the alkalizing agent to the acidified loess is (0.5-2) to 1; preferably, the mass ratio of the alkalizing agent to the acidified loess is (1-1.5) to 1.
In a preferred embodiment, in the step of S3 alkalization, the calcination conditions are: calcining at 350-450 ℃ for 1-5 h; preferably, the calcination conditions are: calcining at 400 deg.c for 2-4 hr.
According to the invention, the alkalizing agent is added for activation treatment, so that the silicate crystal structure in loess can be completely destroyed, and silicon oxide crystals are dissolved out of loess to become amorphous active silica sol.
In a preferred embodiment, in the step of S4 crystallization, the template is N, N-trimethyl-1-adamantylammonium hydroxide (R).
In a preferred embodiment, in the step of S4 crystallization, the pH of the blended slurry is 13 to 14.
In a preferred embodiment, in the step of S4 crystallization, the aging time is 4 to 18 hours in order to ensure the generation of the pore size distribution (micropore-mesopore) of the hierarchical pore molecular sieve SSZ-13; preferably, the aging time is 6 to 12 hours.
The invention aims at increasing the number of crystal nuclei in a slurry system and reducing crystallization reaction time by aging at room temperature, and simultaneously controlling the aging time within a certain time range, wherein the molecular sieve SSZ-13 with Cheng Duoji holes is easier to generate by loess; however, if the aging time is too long, the microporous molecular sieve SSZ-13 with a cubic structure is easy to generate, and the mesoporous molecular sieve SSZ-13 cannot be obtained. Therefore, the aging time range is set, the number of crystal nuclei is controlled, the formation time of the molecular sieve SSZ-13 is shortened, the yield is improved, and the hierarchical pore molecular sieve SSZ-13 is easier to form.
In a preferred embodiment, in the step of crystallization of S4, in order to ensure the formation of the (microporous-mesoporous) hierarchical pore molecular sieve SSZ-13, the crystallization reaction temperature is 150-170 ℃ and the crystallization time is 36-72 h. Preferably, the crystallization reaction device is a closed reaction kettle; more preferably, the crystallization reaction temperature is 160-165 ℃ and the crystallization reaction time is 48-60 h.
In a preferred embodiment, in the step of S4 crystallization, in order to shorten the crystallization time and improve the crystallization effect, molecular sieve SSZ-13 seed crystals may be added into the blended slurry, preferably, the adding amount of the molecular sieve SSZ-13 seed crystals is 1-5% of the mass of the blended slurry; preferably, the adding amount of the molecular sieve SSZ-13 seed crystal is 2-3% of the mass of the prepared slurry.
In a preferred embodiment, after the crystallization step of S4 is completed, the method further comprises filtering, collecting the filter cake, washing to pH 9, and drying. Wherein the washing may be performed by conventional procedures known to those skilled in the art, for example washing the product 1 to 2 times with acidic water having a pH of 2 to 4; then washing the product with deionized water for 2-5 times until the pH=9; preferably, ultrasonic treatment can be further carried out when washing, so as to obtain a high-quality molecular sieve SSZ-13 product with a clean surface. The drying may be performed by any apparatus and method known to those skilled in the art, and preferably, the drying is performed at 80 to 120℃for 2 to 8 hours.
In a preferred embodiment, in the S5 activated Huang Tuji SSZ-13 molecular sieve step, the NH 4 The molar ratio of the addition of Cl to the alkalizing agent in S3 is 1: (1-3), preferably, the NH 4 The molar ratio of the addition of Cl to the alkalizing agent in S3 is 1:2.
in a preferred embodiment, in the S5 activated Huang Tuji SSZ-13 molecular sieve step, the ion exchange reaction conditions are: reacting for 1-3 h at 70-80 ℃; preferably, the ion exchange reaction conditions are: reacting for 2h at 75 ℃; more preferably, in order to enhance the ion exchange effect, the ion exchange may be performed twice under exactly the same treatment conditions.
In a preferred embodiment, in the S5 activated Huang Tuji SSZ-13 molecular sieve step, the conditions of the calcined filter cake are: calcining at 500-600 deg.c for 1-8 hr; preferably, the conditions of the calcined filter cake are: calcining at 550 ℃ for 3-6 h.
Another object of the present invention is to provide an application of a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve, specifically comprising: the loess-based SSZ-13 molecular sieve is applied to the fields of fine chemical industry, environmental protection, petrochemical industry, coal chemical industry and automobile exhaust treatment.
According to the technical scheme provided by the invention, the template agent is less in dosage based on raw materials and scheme design, an aluminum source is not required to be additionally added, only a silicon source is required to be supplemented, the silicon-aluminum ratio in the proportion is improved to 220, the prepared molecular sieve has a spindle body gathered honeycomb structure, and the microcosmic appearance is of a micropore-mesopore multi-level pore characteristic. Compared with the molecular sieve SSZ-13 prepared conventionally in the prior art, the molecular sieve has larger pore diameter and smaller specific surface area, and shows an obvious fusiform structure with spindle aggregation. When the molecular sieve SSZ-13 is used as a reaction catalyst for preparing olefin from methanol, the molecular sieve SSZ-13 is more favorable for generating propylene gas products with larger molecules, and meanwhile, the larger pore diameter of the loess-based molecular sieve SSZ-13 prepared by the invention endows the molecular sieve SSZ-13 with better carbon deposition resistance, so that conditions and directions are provided for large-scale development and use of the molecular sieve SSZ-13.
In a preferred embodiment, the loess-based SSZ-13 molecular sieve is used for preparing low-carbon olefin from methanol and removing NO in automobile exhaust X And the catalyst is used as a catalyst for catalytic reaction in the gas separation and adsorption process.
In a preferred embodiment, the loess-based SSZ-13 molecular sieve is used as a catalyst for preparing olefin from methanol to obtain high-selectivity low-carbon olefin, and specifically comprises the following steps:
and tabletting, crushing and sieving the high-silicon multi-stage Kong Huangtu-base SSZ-13 molecular sieve, taking 0.5-2 g of the molecular sieve to be filled into a fluidized bed reactor, introducing nitrogen as carrier gas, introducing methanol, and reacting at a certain temperature to obtain the low-carbon olefin product.
In a preferred embodiment, the loess-based SSZ-13 molecular sieve is tableted and crushed and then passed through a 50 mesh sieve.
In a preferred embodiment, the nitrogen flow is 30 to 100mL/min.
In a preferred embodiment, the reaction temperature is 400-480 ℃, and the mass concentration of the methanol is as follows: alcohol-water ratio (1-9): 1, the mass airspeed is 2 to 8 hours -1 . Preferably, the reaction temperature is 450 ℃, and the mass concentration of the methanol is as follows: alcohol-water ratio is 7:3, mass space velocity is 5h -1 When (1).
In a preferred embodiment, the loess-based SSZ-13 molecular sieve is used as a catalyst for preparing olefin from methanol, the selectivity of propylene is more than 56%, and the selectivity of ethylene is more than 47%.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. the loess-based molecular sieve SSZ-13 can be simply and rapidly prepared by taking loess as a raw material and activating and crystallizing the loess. From the viewpoint of raw materials, the loess has wide sources, convenient collection and huge reserves, and can greatly reduce the raw material purchasing cost; from the technical point of view, the preparation method has higher safety and lower energy consumption, and can reduce the cost of the production process; in addition, the acidulant, the alkalizing agent and the like used in the production process can be recycled, so that the waste liquid discharge is reduced, and the cost is further reduced. In conclusion, the loess-based SSZ-13 molecular sieve provided by the invention has the advantages of low cost, easiness in preparation and larger price, and can be used for large-scale industrial production.
2. According to the technical scheme provided by the invention, the high-silicon multistage Kong Huangtu-based molecular sieve SSZ-13 can be prepared under the condition that additives and aluminum sources are not needed to be added by controlling the raw material proportion, crystallization reaction conditions and the like. The formula is simple, and the preparation process is simple and safe.
3. From the product, the microstructure of the obtained clay-based molecular sieve SSZ-13 shows a spindle-aggregated honeycomb structure, and the aperture of the clay-based molecular sieve SSZ-13 is provided with micropores and mesopores which coexist in multiple stages, so that the clay-based molecular sieve SSZ-13 can be used as a catalyst to obviously improve the effect of the reaction of preparing olefin from methanol, and especially improve the selectivity of propylene with a larger molecular structure. On the other hand, the molecular sieve SSZ-13 has high silicon-aluminum ratio and contains a small amount of Fe 3+ The ion and the modification thereof can also greatly improve the anti-carbon property and the catalytic activity of the molecular sieve SSZ-13 in the aspect of preparing olefin from methanol.
Drawings
These and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following detailed description of the embodiments of the invention, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is an XRD pattern of a high silicon multistage Kong Huangtu-based molecular sieve SSZ-13 prepared in example 1 and a standard SSZ-13 molecular sieve;
FIG. 2 is an SEM image of a high silicon multistage Kong Huangtu-based molecular sieve SSZ-13 prepared according to example 1;
FIG. 3 is a graph of pore size distribution of high silicon multistage Kong Huangtu-based molecular sieve SSZ-13 prepared in example 1;
FIG. 4 is an N of a high silicon multistage Kong Huangtu-based molecular sieve SSZ-13 prepared in example 1 2 The drawing is sucked.
Detailed Description
For a better understanding of the present invention, those skilled in the art will now make further details with reference to the drawings and the detailed description, but it should be understood that the scope of the invention is not limited by the detailed description.
The embodiment of the invention solves the problems that the synthesis method of the molecular sieve SSZ-13 in the prior art has high synthesis cost, cannot realize large-scale production, causes environmental pollution and the like by providing the low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve and the preparation method and the application thereof. In addition, the invention can also effectively solve the technical problem that the existing SSZ-13 molecular sieve has poor effect in the reaction of preparing olefin from methanol.
The technical scheme of the invention aims to solve the problems, and the general idea is as follows:
unless otherwise indicated, the technical means used in the present invention are conventional means well known to those skilled in the art, and various raw materials, reagents, instruments, equipment, etc. used in the present invention are commercially available or can be prepared by existing methods. The reagents used in the invention are analytically pure unless otherwise specified. The room temperature in the present invention is 25℃unless otherwise specified.
In the present invention, the parts by weight may be those known in the art such as mu g, mg, g, kg, or may be multiples thereof such as 1/10, 1/100, 10 times, 100 times, etc.
In the embodiment of the invention, loess used is produced from northwest China, particularly from Qingyang city in Gansu province. Compared with other earths and raw materials, loess has the advantages of rich resources, no limitation of raw materials and the like, but has complex crystal structure and various components, and the synthesis and performance of the molecular sieve are affected by the mixed crystal components. The chemical composition analysis results of loess are shown in Table 1.
Table 1: loess content of each component
Example 1
Purifying: the loess raw material is washed with deionized water, filtered through a 200 mesh sieve, repeated 5 times, and dried at 120 ℃ for 3 hours. Obtaining purified loess;
acidifying, preparing 20% diluted sulfuric acid solution, adding purified loess 80g, maintaining solid-liquid ratio at 1:4, acidifying at 85deg.C for 5 hr, filtering, washing to neutrality, and oven drying at 120deg.C to obtain acidified loess.
Alkalizing, mixing 20g of acidified loess and 22g of sodium hydroxide solid uniformly, calcining at 400 ℃ for 2 hours, calcining twice, and cooling to room temperature to obtain alkalized loess for later use.
Crystallizing, namely, taking 21g of alkalized loess (10 g of loess and 11g of sodium hydroxide) according to the molar ratio of SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, with the addition of 52.83g of template (N, N, N-trimethyl-1-adamantylammonium hydroxide, 24 wt.%), 313.95g of silica sol (40 wt% SiO) 2 ) 1.3g of seed crystal and 142.287g of deionized water are uniformly stirred, at the moment, the pH=13 is about, the aging is carried out for 8 hours at room temperature, then the seed crystal is transferred into a high-pressure reaction kettle, the high-pressure reaction kettle is placed into an oven to react for 48 hours at the temperature of 165 ℃, after the reaction is finished, the seed crystal is washed by acid solution, the seed crystal is washed by deionized water until the pH=9, the seed crystal is filtered, and the seed crystal is dried for 6 hours at the temperature of 120 ℃ to obtain the unactivated loess-based SSZ-13 molecular sieve.
Activating Huang Tuji SSZ-13 molecular sieve: 7.35g NH 4 Cl, 80g deionized water to prepare NH with the mass concentration of about 10% 4 Adding the Cl solution into all the unactivated loess-based molecular sieves SSZ-13, mixing and stirring, performing ion exchange reaction at the reaction temperature of 75 ℃ for 2 hours, filtering and washing after the exchange is finished, and repeating the ion exchange twice to obtain the filter cake loess-based molecular sieves SSZ-13. Grinding the filter cake into powder, and calcining at 550 ℃ for 4 hours to finally obtain the activated high-silicon multistage Kong Huangtu-based molecular sieve SSZ-13.
The SSZ-13 molecular sieve prepared in the embodiment 1 of the invention is characterized and analyzed as follows:
1. x-ray diffraction analysis
The X-ray diffraction analysis (XRD) is mainly aimed at analyzing crystalline substances in minerals, and components of the crystalline substances in minerals and contents of the components can be obtained by analyzing diffraction peaks of XRD patterns. The present invention performs an X-ray diffraction scan of 10-80 degrees 2 theta on a standard SSZ-13 molecular sieve and the loess-based SSZ-13 molecular sieve prepared in example 1 of the present invention, and the result is shown in FIG. 1.
By comparison, as can be seen from FIG. 1, the characteristic peak-to-peak positions of the clay-based SSZ-13 molecular sieve are basically the same as those of the standard SSZ-13 molecular sieve, which indicates that the SSZ-13 molecular sieve is successfully prepared by taking loess as a raw material in the technical scheme of the invention.
2. Microscopic analysis
The morphology of the material was observed mainly by Scanning Electron Microscopy (SEM), and the average particle size was 5.132 μm as shown in fig. 2.
As can be seen from the figure, the loess-based SSZ-13 molecular sieve prepared by the method has a snail-shaped structure formed by the aggregation of spindles.
3. BET specific surface area test
The specific surface area of the prepared loess-based SSZ-13 molecular sieve is analyzed and detected by adopting a BET specific surface area analyzer, and the specific surface area of the loess-based SSZ-13 molecular sieve prepared by the invention is 425.3m 2 And/g, compared with the common SSZ-13 molecular sieve, the specific surface area is small, and the pore diameter is larger. The pore diameter distribution diagram is shown in figure 3, the pore diameter distribution is 0.5178-51.4956 nm, and the pore volume distribution range is 0.0926-0.1391 cm 3 /g; n of which is 2 The absorption drawing is shown in fig. 4, and the molecular sieve can be seen to have a micropore-mesopore multistage pore characteristic.
From the analysis, the loess-based SSZ-13 molecular sieve prepared by the invention has micropore-mesopore multi-level pore characteristics, and has higher carbon deposition resistance and propylene selectivity.
(II) testing the catalytic Effect of the SSZ-13 molecular sieves prepared in example 1 of the present invention
The catalytic performance of the high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve in the aspect of preparing low-carbon olefin from methanol is evaluated by using a fluidized bed, and the method specifically comprises the following steps of:
tabletting, crushing and sieving the high-silicon multi-stage Kong Huangtu-base SSZ-13 molecular sieve, taking 1g, filling into a fluidized bed reactor, introducing nitrogen as carrier gas, introducing 50mL/min of nitrogen flow, and then introducing methanol, wherein the mass concentration of the methanol is equal to that of the high-silicon multi-stage Kong Huangtu-base SSZ-13 molecular sieveThe alcohol-water ratio is 7:3, the reaction temperature is 450 ℃, and the methanol mass space velocity is 5h -1 The gas obtained was collected and analyzed qualitatively and quantitatively by gas chromatography.
Results determination: the mass selectivity of ethylene and propylene in the pyrolysis gas is 42.53% and 56.32% respectively.
Example 2
Purifying: the loess raw material is washed with deionized water, filtered through a 200 mesh sieve, repeated 5 times, and dried at 120 ℃ for 3 hours. Obtaining purified loess;
acidifying, preparing 20% diluted sulfuric acid solution, adding purified loess 80g, maintaining solid-liquid ratio at 1:4, acidifying at 85deg.C for 5 hr, filtering, washing to neutrality, and oven drying at 120deg.C to obtain acidified loess.
Alkalizing, mixing 20g of acidified loess and 22g of sodium hydroxide solid uniformly, calcining for 4 hours at 400 ℃, calcining for two times, and cooling to room temperature to obtain alkalized loess for later use.
Crystallizing, namely, taking 21g of alkalized loess (10 g of loess and 11g of sodium hydroxide) according to the molar ratio of SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, with the addition of 52.83g of template (N, N, N-trimethyl-1-adamantylammonium hydroxide, 24 wt.%), 313.95g of silica sol (40 wt% SiO) 2 ) 142.287g of deionized water are uniformly stirred, at the moment, the pH=13 is aged for 12 hours at room temperature, then the mixture is transferred into a high-pressure reaction kettle, the mixture is placed into an oven to react for 60 hours at 160 ℃, after the reaction is finished, the mixture is washed by an acid solution, washed by deionized water until the pH=9, filtered and dried for 6 hours at about 120 ℃ to obtain the unactivated loess-based SSZ-13 molecular sieve.
Activating Huang Tuji SSZ-13 molecular sieve: 7.35g NH 4 Cl, 80g deionized water to prepare NH with the mass concentration of about 10% 4 Adding the Cl solution into all the unactivated loess-based molecular sieves SSZ-13, mixing and stirring, performing ion exchange reaction at the reaction temperature of 80 ℃ for 2 hours, filtering and washing after the reaction is finished, and repeating the ion exchange twice to obtain the filter cake loess-based molecular sieves SSZ-13. Grinding the filter cake into powder, calcining at 550deg.C for 4 hr, and finallyObtaining the active loess-based molecular sieve SSZ-13.
Characterization analysis: microscopic analysis shows that the loess-based molecular sieve prepared by the method is in a spindle aggregation honeycomb structure, the pore diameter of the loess-based molecular sieve has micropores-mesopores concurrent multistage pores, and specific test data are as follows: specific surface area of 456.4m 2 Per gram, the pore size distribution range is 0.5055-50.3277 nm, and the pore volume distribution range is 0.0893-0.1320 cm 3 And/g, the average particle diameter is 5.089. Mu.m.
The catalytic performance of the high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve in the preparation of low-carbon olefin from methanol was evaluated under the same conditions as in example 1, and the results were as follows: the mass selectivity of ethylene and propylene in the pyrolysis gas is 44.87% and 52.65% respectively.
Example 3
Purifying: the loess raw material is washed with deionized water, filtered through a 200 mesh sieve, repeated 5 times, and dried at 120 ℃ for 2 hours. Obtaining purified loess;
acidifying, namely preparing mixed acid solution with the mass concentration of 25% by volume ratio of dilute hydrochloric acid to dilute nitric acid of 1:1, adding 80g of purified loess, keeping the solid-liquid ratio of 1:4, acidifying for 6 hours at 80 ℃, filtering, washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
Alkalizing, mixing 40g of acidified loess and 40g of sodium hydroxide solid uniformly, calcining at 450 ℃ for 4 hours, and cooling to room temperature to obtain alkalized loess for later use.
Crystallizing to obtain 10g of alkalized loess (5 g of loess, 5g of sodium hydroxide) according to the ratio of SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, 26.42g of template (N, N, N-trimethyl-1-adamantylammonium hydroxide, 24 wt%) 156.98g of silica sol (40 wt% SiO) 2 ) 71.144g of deionized water are uniformly stirred, at the moment, the pH=13 is aged for 8 hours at room temperature, then the mixture is transferred into a high-pressure reaction kettle, the mixture is placed into an oven to react for 72 hours at 160 ℃, after the reaction is finished, the mixture is washed by an acid solution, washed by deionized water until the pH=9, filtered and dried for 6 hours at about 120 ℃ to obtain the unactivated loess-based SSZ-13 molecular sieve.
Activating Huang Tuji SSZ-13 molecular sieve: will 3.675g NH 4 Cl, 40g deionized water to prepare NH with mass concentration of about 10% 4 Adding the Cl solution into all the unactivated loess-based molecular sieves SSZ-13, mixing and stirring, performing ion exchange reaction at the reaction temperature of 80 ℃ for 2 hours, filtering and washing after the reaction is finished, and repeating the ion exchange twice to obtain the filter cake loess-based molecular sieves SSZ-13. Grinding the filter cake into powder, and calcining at 550 ℃ for 4 hours to finally obtain the active loess-based molecular sieve SSZ-13.
Characterization analysis: microscopic analysis shows that the loess-based molecular sieve prepared by the method is in a spindle aggregation honeycomb structure, the pore diameter of the loess-based molecular sieve has micropores-mesopores concurrent multistage pores, and specific test data are as follows: specific surface area of 463.2m 2 Per gram, the pore size distribution range is 0.5011-48.1835 nm, and the pore volume distribution range is 0.0833-0.1181 cm 3 And/g, the average particle diameter is 4.814. Mu.m.
The catalytic performance of the high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve in the preparation of low-carbon olefin from methanol was evaluated under the same conditions as in example 1, and the results were as follows: the mass selectivity of ethylene and propylene in the pyrolysis gas is 47.63% and 50.47%.
Example 4
Purifying: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120deg.C for 3 hr. Obtaining purified loess;
acidifying, namely preparing mixed acid solution with the mass concentration of 25% by volume ratio of dilute hydrochloric acid to dilute nitric acid of 1:1, adding 80g of purified loess, keeping the solid-liquid ratio of 1:4, acidifying for 6 hours at 80 ℃, filtering, washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
Alkalizing, mixing 40g of acidified loess and 40g of sodium hydroxide solid uniformly, calcining for 3 hours at 450 ℃, and cooling to room temperature for later use.
Crystallizing to obtain 10g of alkalized loess (5 g of loess, 5g of sodium hydroxide) according to the ratio of SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, 26.42g of template (N, N, N-trimethyl-1-adamantylammonium hydroxide, 24 wt%) 1 were added56.98g of silica sol (40 wt% SiO) 2 ) 71.144g of deionized water and 0.7g of seed crystal are uniformly stirred, at the moment, the pH=13 is about, the mixture is aged for 8 hours at room temperature, then the mixture is transferred into a high-pressure reaction kettle, the high-pressure reaction kettle is placed into an oven to react for 60 hours at 165 ℃, after the reaction is finished, the mixture is washed by acid solution and deionized water, the mixture is washed to pH=9, the mixture is filtered, and the mixture is dried for 6 hours at about 120 ℃ to obtain the unactivated loess-based SSZ-13 molecular sieve.
Activating Huang Tuji SSZ-13 molecular sieve: will 3.675g NH 4 Cl, 40g deionized water to prepare NH with mass concentration of about 10% 4 Adding the Cl solution into all the unactivated loess-based molecular sieves SSZ-13, mixing and stirring, performing ion exchange reaction at the reaction temperature of 80 ℃ for 2 hours, filtering and washing after the reaction is finished, and repeating the ion exchange twice to obtain the filter cake loess-based molecular sieves SSZ-13. Grinding the filter cake into powder, and calcining at 550 ℃ for 6 hours to finally obtain the active loess-based molecular sieve SSZ-13.
Characterization analysis: microscopic analysis shows that the loess-based molecular sieve prepared by the method is in a spindle aggregation honeycomb structure, the pore diameter of the loess-based molecular sieve has micropores-mesopores concurrent multistage pores, and specific test data are as follows: specific surface area of 451.43m 2 Per gram, the pore diameter distribution range is 0.5255-51.3277 nm, and the pore volume distribution range is 0.0893-0.1320 cm 3 And/g, the average particle diameter is 5.589. Mu.m.
The catalytic performance of the high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve in the preparation of low-carbon olefin from methanol was evaluated under the same conditions as in example 1, and the results were as follows: the selectivity of ethylene and propylene in the pyrolysis gas is 45.78 and 52.55 percent.
Example 5
Purifying: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120deg.C for 2 hr. Obtaining purified loess;
acidifying, preparing 25% diluted hydrochloric acid solution, adding the purified loess 40g, maintaining solid-liquid ratio at 1:4, acidifying at 90deg.C for 5 hr, filtering, washing to neutrality, and oven drying at 120deg.C to obtain acidified loess.
Dry alkalization, namely, uniformly mixing 30g of acidified loess with 30g of sodium hydroxide solid, calcining for 4 hours at 450 ℃, and cooling to room temperature for later use.
Crystallizing to obtain 10g of alkalized loess (5 g of loess, 5g of sodium hydroxide) according to the ratio of SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, 26.42g of template (N, N, N-trimethyl-1-adamantylammonium hydroxide, 24 wt%) 156.98g of silica sol (40 wt% SiO) 2 ) 71.144g of deionized water are uniformly stirred, at the moment, the pH=13 is aged for 12 hours at room temperature, then the mixture is transferred into a high-pressure reaction kettle, the mixture is placed into an oven to react for 72 hours at 160 ℃, after the reaction is finished, the mixture is washed by an acid solution, washed by deionized water until the pH=9, filtered and dried for 6 hours at about 120 ℃ to obtain the unactivated loess-based SSZ-13 molecular sieve.
Activating Huang Tuji SSZ-13 molecular sieve: will 3.675g NH 4 Cl, 40g deionized water to prepare NH with mass concentration of about 10% 4 Adding the Cl solution into all the unactivated loess-based molecular sieves SSZ-13, mixing and stirring, performing ion exchange reaction at the reaction temperature of 75 ℃ for 2 hours, filtering and washing after the reaction is finished, and repeating the ion exchange twice to obtain the filter cake loess-based molecular sieves SSZ-13. Grinding the filter cake into powder, and calcining at 550 ℃ for 4 hours to finally obtain the active loess-based molecular sieve SSZ-13.
Characterization analysis: microscopic analysis shows that the loess-based molecular sieve prepared by the method is in a spindle aggregation honeycomb structure, the pore diameter of the loess-based molecular sieve has micropores-mesopores concurrent multistage pores, and specific test data are as follows: specific surface area of 486.19m 2 Per gram, the pore diameter distribution range is 0.4925-49.4356 nm, and the pore volume distribution range is 0.0881-0.1810 cm 3 And/g, the average particle diameter is 5.289. Mu.m.
The catalytic performance of the high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve in preparing low-carbon olefin from methanol was evaluated under the same conditions as in example 1, and the results were as follows: the mass selectivity of ethylene and propylene in the pyrolysis gas is 44.56% and 49.61%.
In summary, examples 1 and 4 of the present application are preparation schemes with seed crystals, and examples 2, 3 and 5 are preparation schemes without seed crystals, and it can be seen that the obtained high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieves are all in a spindle-aggregated honeycomb structure, have larger pore diameters and smaller specific surface areas, and are used as catalysts for preparing low-carbon olefins, and have higher selectivity to ethylene and propylene in pyrolysis gas.
The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (10)

1. A low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve is characterized in that loess is used as a raw material, after activation treatment, only a silicon source, a template agent and water are added for blending, and after aging, crystallization and ion exchange, the multistage high-silicon loess-base molecular sieve SSZ-13 with micropores-mesopores and multiple holes is obtained by calcination;
the high-silicon hierarchical pore molecular sieve SSZ-13 is in a spindle body aggregation honeycomb structure, and the specific surface area is 425.3-486.19 m 2 Per gram, the pore size distribution range is 0.4925-51.4956 nm, and the pore volume distribution range is 0.0833-0.1810 cm 3 And/g, the average particle size is 4.814-5.589 μm.
2. The method for preparing the low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve according to claim 1, which comprises the following steps:
s1, purifying: taking loess in northwest area as raw material, washing with water, and drying to obtain purified loess;
s2, acidizing: adding an acidulant into the product of the step, and performing an acidification reaction to obtain acidified loess;
s3, alkalizing: mixing the product of the step with an alkalizing agent, and calcining to obtain alkalized loess;
s4, crystallizing: adding a silicon source, a template agent and water into the product of the last step to lead the mole ratio of raw materials in the system to be SiO 2 ∶Al 2 O 3 Template agent Na 2 O∶H 2 O=220:1:6:24:2060, resulting in a formulated slurry; aging the prepared slurry at room temperature, and performing crystallization reaction under certain conditions to obtain an unactivated loess-based SSZ-13 molecular sieve;
s5 activated Huang Tuji SSZ-13 molecular sieves: combining unactivated loess-based molecular sieve SSZ-13 with NH 4 And (3) mixing Cl solutions to perform ion exchange reaction, filtering, collecting filter cakes, washing and calcining to obtain the active high-silicon multistage Kong Huangtu-based molecular sieve SSZ-13.
3. The method for preparing a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve according to claim 2, wherein in the S1 purification step, the molar ratio of silicon to aluminum in loess is SiO 2 ∶Al 2 O 3 ＝(6.1～8.5)∶1。
4. The method for preparing a low cost high silicon multistage Kong Huangtu based SSZ-13 molecular sieve according to claim 2, wherein in the step of S3 alkalizing, the calcination conditions are as follows: calcining at 350-450 deg.c for 1-5 hr.
5. The method for preparing a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve according to claim 2, wherein in the step of S4 crystallization, the template agent is N, N, N-trimethyl-1-adamantylammonium hydroxide; the aging time is 4-18 hours; the crystallization reaction temperature is 150-170 ℃ and the crystallization time is 36-72 h.
6. The method for preparing a low-cost high-silicon multistage Kong Huangtu-based SSZ-13 molecular sieve according to claim 5, wherein in the step of S4 crystallization, molecular sieve SSZ-13 seed crystals are added into the prepared slurry, and the adding amount of the seed crystals is 2-5% of the mass of the prepared slurry.
7. The method for preparing a low cost high silicon multi-stage Kong Huangtu base SSZ-13 molecular sieve according to claim 2, wherein in the step of S5 activating Huang Tuji SSZ-13 molecular sieve, the NH is 4 The molar ratio of the addition of Cl to the alkalizing agent in S3 is 1: (1-3).
8. The application of the low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve prepared by the method according to claim 2 or any one of claims 3-7, which is characterized in that the loess-base SSZ-13 molecular sieve is applied to the fields of fine chemical industry, environmental protection, petrochemical industry, coal chemical industry and automobile exhaust treatment.
9. The use as claimed in claim 8, wherein the loess-based SSZ-13 molecular sieve is used as a catalyst for preparing olefin from methanol to obtain high-selectivity light olefin, comprising the following steps:
and tabletting, crushing and sieving the high-silicon multi-stage Kong Huangtu-base SSZ-13 molecular sieve, taking 0.5-2 g of the molecular sieve to be filled into a fluidized bed reactor, introducing nitrogen as carrier gas, introducing methanol, and reacting at a certain temperature to obtain the low-carbon olefin product.
10. The use as claimed in claim 9, wherein the loess-based SSZ-13 molecular sieve is used as a catalyst for preparing olefin from methanol, the selectivity of propylene is up to 56% or more, and the selectivity of ethylene is up to 47% or more.
CN202311566611.8A 2023-11-22 2023-11-22 Low-cost high-silicon multistage Kong Huangtu-base SSZ-13 molecular sieve and preparation method and application thereof Pending CN117566757A (en)

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