Disclosure of Invention
The invention aims to provide a synthesis method of an MTT zeolite molecular sieve with a short-axis morphology, which aims to overcome the defect that an expensive auxiliary template agent is required to be used when the MTT zeolite molecular sieve with the short-axis morphology is prepared in the prior art.
In order to solve the above problems, the present invention provides a method for synthesizing a MTT zeolite molecular sieve having a short-axis morphology, comprising the following steps:
s1, uniformly mixing a silicon oxide source, an aluminum oxide source, an alkali metal source MeOH, an organic template agent R and deionized water, adding MTT molecular sieve seed crystal to form synthetic gel, and synthesizing SiO in the gel2/Al2O3=30~150,R/SiO2=0.3~0.9;MeOH/SiO2=0.3~0.9,H2O/SiO230-50 percent of MTT crystal seed, wherein the addition amount of the MTT crystal seed accounts for 1-5 percent of the total mass of the gel, and the organic template agent R is one or more of dimethylamine, isopropylamine and N, N-dimethyldiamide;
s2, under the sealing condition, keeping the temperature of the synthesized gel at 140-180 ℃ at the stirring speed of 300rpm and the heating speed of 5-20 ℃/min for 24-48 hours, and then cooling, filtering and drying to obtain the MTT zeolite molecular sieve with the axial-diameter length ratio of less than 10.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, has the advantages that the silicon-aluminum ratio of the synthesized MTT zeolite molecular sieve is 30-60, the crystallization temperature is 160-170 ℃, and the axial-diameter length ratio is less than 5.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft morphology, wherein a silicon oxide source is one or more of silica sol, silica gel, white carbon black, coarse silica gel and esters containing silicon oxide components. The ester containing the silicon oxide component may be methyl orthosilicate or ethyl orthosilicate, but is not limited thereto.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft shape, wherein an alumina source is one or more of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum hydroxide and pseudo-boehmite.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short-axis morphology, wherein an alkali metal source MeOH is NaOH and/or KOH.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft morphology, wherein an MTT molecular sieve crystal seed is a crystal with an MTT molecular sieve framework structure, and specifically can be one or more of ZSM-23, SSZ-32, KZ-1, EU-13 and ISI-6, but not limited thereto, and the crystal seed can be a crystal seed without an organic template or a crystal seed containing the organic template.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology comprises the following step of adding MTT crystal seeds in an amount of 1.5-4.5% of the total mass of the gel, and preferably, adding the MTT crystal seeds in an amount of 2-3% of the total mass of the gel.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, is characterized in that the stirring speed of the synthesized gel is 200-300 rpm.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, is characterized in that the temperature rise rate of the synthesized gel is 10-20 ℃/min.
The invention realizes the purpose of synthesizing the MTT zeolite molecular sieve with the short-axis crystal morphology under the relatively economic condition by simultaneously controlling the stirring speed and the heating rate and selecting specific crystal seeds. In the process, the proper stirring speed is controlled, the exchange process of substances in a reaction system is increased, the local concentration difference is reduced, and the reaction is rapidly carried out; meanwhile, the reaction rate is accelerated by utilizing higher temperature rise rate, the crystallization process can be completed in a short time, and the grain size of the molecular sieve is reduced; and proper seed crystal is selected as nucleating agent, which can provide crystal nucleus for the system, so that the reaction can be directly carried out; if no seed crystal exists, the growth of the molecular sieve needs a nucleation induction period of 1-2 days, and the nucleation amount is low, so that the crystal grows.
The invention has the beneficial effects that:
the method of the invention adopts a single cheap template agent, seed crystal auxiliary nucleation and rapid temperature rise method to complete the crystallization process in a short time. The MTT zeolite molecular sieve with the short-axis crystal morphology with the axial-to-diameter ratio of less than 10 and even less than 5 is formed.
Detailed Description
The present invention is described in further detail below by way of examples, which should not be construed as limiting the invention thereto.
A method for synthesizing an MTT zeolite molecular sieve with short-axis morphology comprises the following steps:
s1, uniformly mixing a silicon oxide source, an aluminum oxide source, an alkali metal source MeOH, an organic template agent R and deionized water, adding MTT molecular sieve seed crystal to form synthetic gel, and synthesizing SiO in the gel2/Al2O3=30~150,R/SiO2=0.3~0.9;MeOH/SiO2=0.3~0.9,H2O/SiO230-50 percent of MTT crystal seed, wherein the addition amount of the MTT crystal seed accounts for 1-5 percent of the total mass of the gel, and the organic template agent R is one or more of dimethylamine, isopropylamine and N, N-dimethyldiamide;
s2, under the sealing condition, keeping the temperature of the synthesized gel at 140-180 ℃ at the stirring speed of 300rpm and the heating speed of 5-20 ℃/min for 24-48 hours, and then cooling, filtering and drying to obtain the MTT zeolite molecular sieve with the axial-diameter length ratio of less than 10.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, has the advantages that the silicon-aluminum ratio of the synthesized MTT zeolite molecular sieve is 30-60, the crystallization temperature is 160-170 ℃, and the axial-diameter length ratio is less than 5.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft morphology, wherein a silicon oxide source is one or more of silica sol, silica gel, white carbon black, coarse silica gel and esters containing silicon oxide components. The ester containing the silicon oxide component may be methyl orthosilicate or ethyl orthosilicate, but is not limited thereto.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft shape, wherein an alumina source is one or more of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum hydroxide and pseudo-boehmite.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short-axis morphology, wherein an alkali metal source MeOH is NaOH and/or KOH.
The invention relates to a synthesis method of an MTT zeolite molecular sieve with a short shaft morphology, wherein an MTT molecular sieve crystal seed is a crystal with an MTT molecular sieve framework structure, and specifically can be one or more of ZSM-23, SSZ-32, KZ-1, EU-13 and ISI-6, but not limited thereto, and the crystal seed can be a crystal seed without an organic template or a crystal seed containing the organic template.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology comprises the following step of adding MTT crystal seeds in an amount of 1.5-4.5% of the total mass of the gel, and preferably, adding the MTT crystal seeds in an amount of 2-3% of the total mass of the gel.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, is characterized in that the stirring speed of the synthesized gel is 200-300 rpm.
The synthesis method of the MTT zeolite molecular sieve with the short-axis morphology, disclosed by the invention, is characterized in that the temperature rise rate of the synthesized gel is 10-20 ℃/min.
Example 1:
the feeding ratio of silicon to aluminum is 110, the usage amount of the seed crystal is 2.2 percent, and the MTT zeolite molecular sieve with the axial-diameter ratio less than 10 is quickly synthesized.
Synthesizing the MTT zeolite molecular sieve with the axial-diameter ratio of less than 10. The specific operation is as follows: 0.364g of Al was added under stirring2(SO4)3·18H2Dissolving O in 30g of water, then adding 0.48g of NaOH, and fully stirring to form a clear solution A; 2.5g of Isopropylamine (IPA) are weighed out and added to solution A, after dissolution, 12g of silica sol (containing SiO) are added230 percent of the mass) is stirred to form a uniform gel B; then adding 1.0g of MTT zeolite seed crystal ZSM-23, and continuing stirring for 10min to form gel C; the concrete composition is as follows: 109.00SiO2/1.00Al2O3/4.36Na2O/77.00IPA/3.0H2SO4/3036.00H2And O. Transferring the gel C into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, rapidly enabling the reaction kettle to reach 170 ℃ at the heating rate of 5 ℃/min, controlling the stirring rate at 300rpm, and carrying out hydrothermal reaction for 24 hours. After cooling, the product was filtered at room temperature, washed with water and dried at 80 ℃ to obtain 4.0g of sample. The product is the MTT zeolite molecular sieve with the axial-diameter ratio of 8-10 according to XRD characterization. Fig. 1 and 2 show the following.
Example 2:
the feeding silica-alumina ratio is 60, the using amount of the seed crystal is 3.0 percent, and the MTT zeolite molecular sieve with the axial-diameter ratio less than 5 is quickly synthesized.
Synthesizing the MTT zeolite molecular sieve with the axial-diameter ratio of less than 5. The specific operation is as follows: 0.664g of Al was added under stirring2(SO4)3·18H2Dissolving O in 35g of water, then adding 0.5g of NaOH, and fully stirring to form a clear solution A; 2.7g of Isopropylamine (IPA) are weighed out and added to solution A, after dissolution, 12g of silica sol (containing SiO) are added230 percent of the mass) is stirred to form a uniform gel B; then adding 1.5g of MTT zeolite seed crystal KZ-1, and continuing stirring for 10min to form gel C; the concrete composition is as follows: 60.00SiO2/1.00Al2O3/6.25Na2O/45.8IPA/3.0H2SO4/2430H2And O. Transferring the gel C into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, rapidly enabling the reaction kettle to reach 170 ℃ at the heating rate of 20 ℃/min, controlling the stirring rate at 200rpm, and carrying out hydrothermal reaction for 24 hours. After cooling, the product was filtered at room temperature, washed with water and dried at 80 ℃ to obtain 4.2g of a sample. The product is the MTT zeolite molecular sieve with the axial-diameter ratio of 4-5 according to XRD characterization. Fig. 3 and 4.
Example 3:
the feeding ratio of silicon to aluminum is 110, the usage amount of the seed crystal is 2.2 percent, and the MTT zeolite molecular sieve with the axial-diameter ratio less than 10 is quickly synthesized.
Synthesizing the MTT zeolite molecular sieve with the axial-diameter ratio of less than 10. The specific operation is as follows: 0.364g of Al was added under stirring2(SO4)3·18H2Dissolving O in 25.5g of water, adding 0.48g of NaOH, and fully stirring to form a clear solution A; 6.4g of dimethylamine (DMA, 30% by mass solution) are weighed out and added to the solution A, after dissolution, 12g of silica sol (containing SiO) are added230 percent of the mass) is stirred to form a uniform gel B; then adding 1.0g of MTT zeolite seed crystal SSZ-32, and continuing stirring for 10min to form gel C; the concrete composition is as follows: 109.00SiO2/1.00Al2O3/4.36Na2O/79.00DMA/3.0H2SO4/3036.00H2And O. Transferring the gel C into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, rapidly enabling the reaction kettle to reach 170 ℃ at the heating rate of 20 ℃/min, controlling the stirring rate at 300rpm, and carrying out hydrothermal reaction for 28 h. After cooling, the product is filtered at room temperature, washed with water, dried at 80 ℃, and then represented by XRD, the product is the MTT zeolite molecular sieve with the axial-to-diameter ratio of less than 10.
Comparative example 1
The feeding ratio of silicon to aluminum is 110, the stirring intensity is high, the low-temperature rate of rise is high, MTT crystal seeds are not introduced, and the MTT zeolite molecular sieve with the axial-to-diameter ratio of more than 20 is synthesized.
Gel B was prepared as described in example 1. The concrete composition is as follows: 109.00SiO2/1.00Al2O3/43.6Na2O/77.00IPA/3.0H2SO4/3036.00H2And O. Transferring the gel B into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, enabling the reaction kettle to reach 170 ℃ at the heating rate of 0.5 ℃/min, controlling the stirring rate at 300rpm, and carrying out hydrothermal reaction for 48 hours. After cooling, the product was filtered at room temperature to give a 3.96g sample. The product is the MTT zeolite molecular sieve with the axial-diameter ratio of more than 20 according to XRD and SEM characteristics. Fig. 5 and 6.
Comparative example 2
The feeding ratio of silicon to aluminum is 110, the stirring intensity is low, the temperature rising rate is high, MTT crystal seeds are introduced, and the MTT zeolite molecular sieve with the axial ratio of more than 15 is synthesized.
Gel C was prepared as described in example 1. The concrete composition is as follows: 109.00SiO2/1.00Al2O3/43.6Na2O/77.00IPA/3.0H2SO4/3036.00H2O。Transferring the gel C into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, enabling the reaction kettle to reach 170 ℃ at the heating rate of 5 ℃/min, controlling the stirring rate at 30rpm, and carrying out hydrothermal reaction for 48 hours. After cooling, the product was filtered at room temperature to give a 3.88g sample. The product is the MTT zeolite molecular sieve with the axial-diameter ratio of more than 15 according to XRD and SEM characteristics. Fig. 7 and 8 show the following.
Comparative example 3
The feeding ratio of silicon to aluminum is 110, the stirring intensity is high, the high temperature raising rate is high, MTT crystal seeds are not introduced, and the MTT zeolite molecular sieve with the axial ratio of more than 20 is synthesized.
Gel B was prepared as described in example 1. The concrete composition is as follows: 109.00SiO2/1.00Al2O3/43.6Na2O/77.00IPA/3.0H2SO4/3036.00H2And O. Transferring the gel B into a 100mL stainless steel reaction kettle with a polytetrafluoroethylene lining, enabling the reaction kettle to reach 170 ℃ at the heating rate of 5 ℃/min, controlling the stirring rate at 300rpm, and carrying out hydrothermal reaction for 48 hours. After cooling, the product was filtered at room temperature to give a 3.96g sample. The product is the MTT zeolite molecular sieve with the axial-diameter ratio of more than 20 according to XRD and SEM characteristics.
The method of the invention adopts a single cheap template agent, seed crystal auxiliary nucleation and rapid temperature rise method to complete the crystallization process in a short time. The MTT zeolite molecular sieve with the short-axis crystal morphology with the axial-to-diameter ratio of less than 10 and even less than 5 is formed.
The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.