CN115959678B - A ZSM-12 molecular sieve and preparation method thereof - Google Patents
A ZSM-12 molecular sieve and preparation method thereof Download PDFInfo
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Abstract
本发明涉及一种ZSM‑12分子筛的制备方法，其包括以下步骤：将铝源Y溶于水中，搅拌至为澄清溶液；将无机碱M溶于水中，搅拌至为澄清溶液后滴加入澄清溶液，得混合溶液；将模板剂Q1、模板剂Q2溶于水中，搅拌至为澄清溶液后滴加入混合溶液；将硅源X加入混合溶液中；加入水混合均匀后得到凝胶，最终凝胶中H2O与硅源X的摩尔之比为10‑35:1；所得凝胶在150‑180℃晶化10‑96h；将晶化后的产物用蒸馏水洗涤，在100‑120℃下干燥2‑3h，在300‑600℃下焙烧10‑20h。该方法合成出的树枝状ZSM‑12分子筛具有更高的双支链异构化性能。
The present invention relates to a preparation method of a ZSM-12 molecular sieve, which comprises the following steps: dissolving an aluminum source Y in water and stirring to obtain a clear solution; dissolving an inorganic base M in water and stirring to obtain a clear solution and then dropping the clear solution to obtain a mixed solution; dissolving a template agent Q1 and a template agent Q2 in water and stirring to obtain a clear solution and then dropping the clear solution; adding a silicon source X to the mixed solution; adding water and mixing uniformly to obtain a gel, wherein the molar ratio of H2O to the silicon source X in the final gel is 10-35:1; the obtained gel is crystallized at 150-180°C for 10-96h; washing the crystallized product with distilled water, drying at 100-120°C for 2-3h, and calcining at 300-600°C for 10-20h. The dendritic ZSM-12 molecular sieve synthesized by the method has higher double-branched chain isomerization performance.
Description
Technical Field
The invention relates to the field of molecular sieve catalytic material synthesis, in particular to a dendritic ZSM-12 molecular sieve and a preparation method thereof.
Background
ZSM-12 zeolite is a high-silicon zeolite with one-dimensional twelve-membered ring pore channel structure. It was synthesized for the first time in 1974 by Rosinski and Rubin et al, and the pore size of the ZSM-12 zeolite made it excellent in catalytic performance during isomerization, hydrocarbon cracking and conversion, etc. During the last decades, researchers have made extensive research efforts on the synthesis of ZSM-12 zeolite. Among these, the template agents used in the synthesis of ZSM-12 zeolite were found to be various in types, such as tetraethylammonium, benzyltrimethylammonium, bisquaternary ammonium salts, and the like. The ZSM-12 molecular sieve synthesized by using different types of templates can obtain products with different morphologies, and can obtain rod-shaped, spherical, block-shaped and other morphologies. Products of different morphologies generally have an impact on catalytic performance.
The patent application CN 106517240A prepares a snowflake ZSM-12 molecular sieve by designing a novel template; the addition amount of each reaction raw material in the process of synthesizing the ZSM-12 molecular sieve is as follows: 15-40H 2O:SiO2:0-0.01Al2O3:0.06-0.14Na2 O or K 2 O, 0.1-0.3 template agent. The novel template agent can be obtained by reacting methyl pyrrolidine with dichlorobenzene in ethanol for 2 days, and is not easy to obtain.
Patent CN 106966408B reacts at least one of 1, 4-p-dichlorobenzyl, α' -dibromo-p-xylene and 1, 4-benzenediol with diamine species to obtain a bifunctional template agent, and synthesizing a hierarchical pore ZSM-12 molecular sieve through the template agent. The bifunctional template agent in the patent cannot be directly obtained from the market and needs to be synthesized by oneself.
Patent US 8679451 B2 prepares ZSM-12 as an aggregate using 1, 6-bis (2, 3-dimethylimidazole) hexane with another organic amine as a dual template agent in the form of aggregates, wherein each aggregate comprises a plurality of elongated crystals. Each individual crystallite is needle-shaped, having a width of between 15 and 25nm and a length of between 60 and 80 nm. The method also has the problems of difficult preparation and difficult acquisition of the template agent.
The patent CN 106698465B restricts the growth of crystals by adding micron-sized carbon materials, so as to prepare the ZSM-12 molecular sieve smaller than 100 nm; this method of adding a hard template, while allowing a molecular sieve of uniform size to be obtained, increases the difficulty in removing the template at a later stage.
Patent application CN104445262a produces ZSM-12 molecular sieves with specific crystal orientations by modifying the template, changing the aluminum source. The molecular sieve preferentially grows along at least one crystal face of (0, 2), (3,0,0) (0,0,6). But the patent does not mention the growth variations of other crystal planes than the above three.
The prior art mainly controls the synthesis morphology of the ZSM-12 molecular sieve by changing the type of the template, and besides the common template, the template for forming ZSM-12 with specific morphology is expensive, and some templates need to be prepared at present and are not easy to obtain.
Disclosure of Invention
Aiming at the problems that the template agent for synthesizing ZSM-12 molecular sieve with specific morphology in the prior art is expensive, some of the template agent needs to be prepared at present and is not easy to obtain, the invention provides a ZSM-12 molecular sieve and a preparation method thereof, and the preparation method can use the template agent which is easy to obtain and a double-template agent method to synthesize the ZSM-12 molecular sieve with dendritic structure. The product has high crystallinity, does not contain other crystal impurities, and synthesizes ZSM-12 molecular sieves with different scales, and the scale range is different from 5-13 mu m.
In addition, the preparation method of the ZSM-12 molecular sieve provided by the invention promotes the growth of the (1, 0) crystal face of the molecular sieve, inhibits the growth of the (0, 1, 5) crystal face, promotes the growth of ZSM-12 along the x-axis direction, and can know that the shape of the ZSM-12 molecular sieve is regulated and controlled to be a specific dendritic shape. Compared with the conventional single template agent synthesis method, the dendritic ZSM-12 molecular sieve synthesized by the method has higher double branched chain isomerization performance.
In order to achieve the above purpose, the invention provides a preparation method of ZSM-12 molecular sieve, comprising the following steps:
(1) Firstly, dissolving an aluminum source Y in water, and stirring to obtain a clear solution;
(2) Dissolving inorganic alkali M in water, stirring until the solution is clear, and then dropwise adding the clear solution in the step (1) to obtain a mixed solution;
(3) Dissolving a template agent Q1 and a template agent Q2 in water, stirring until the solution is clear, and then dropwise adding the mixed solution in the step (2);
(4) Adding a silicon source X into the mixed solution in the step (3);
(5) Adding water, uniformly mixing to obtain gel, wherein the molar ratio of H 2 O to silicon source X in the final gel is 10-35:1;
(6) Crystallizing the gel at 150-180deg.C for 10-96 hr;
(7) Washing the crystallized product with distilled water, drying at 100-120deg.C for 2-3 hr, and roasting at 300-600deg.C for 10-20 hr;
The molar ratio of each material in the synthesis mixture obtained in the step (7) is X:Y=70-150:1, M:X=0.01-0.4:1, (Q1+Q2) X=0.20-0.40:1, and Q1:Q2=1.7-2.5:1; preferably, X: y=100-130:1, m: x=0.05-0.2:1, (q1+q2): x=0.20-0.35:1, q1: q2=1.8-2.4:1.
Specifically, the template agent Q1 is a main structure guiding agent, and the cooperation of alkali metal ions and the template agent Q2 can control the crystal form of ZSM-12 to grow along a specific direction and a specific crystal face, so that the molecular sieve with a specific morphology is finally formed.
The 2 theta value A=7.28+/-0.10 and B=20.59+/-0.10 of the corresponding characteristic peaks of the molecular sieve, the corresponding crystal faces are (1, 0) and (0, 1, 5) respectively, and after the template agent Q2 is added, the molecular sieve grows along the (1, 0) crystal face and inhibits the growth of the (0, 1, 5) crystal face. When only the template Q1 was used, the relative intensity was in the range of a/b=1 to 10, and after the template Q2 was added, the relative intensity was in the range of a/b=0.1 to 0.5.
The (1, 0) crystal face of ZSM-12 intersects with the x axis, and after the template agent Q2 is added, the molecular sieve is more beneficial to growth along the x axis direction. The (0, 1, 5) crystal face is parallel to the x axis, and after the template agent Q2 is added, the growth of the crystal face can be inhibited, so that the axial diameter ratio of the molecular sieve is longer, and finally a dendritic structure is formed.
The method is characterized in that a dendritic ZSM-12 molecular sieve is used as a catalyst, n-dodecane is used as a raw material, and the conversion rate of the isomerization of the double branched chain of the product is analyzed by contacting the raw material with a bed catalyst. The specific reaction parameters are as follows: reaction temperature: 220-260 ℃ and 2-4MPa.
Specifically, in the invention, the gel is required to be configured under milder conditions, the feeding sequence is an aluminum source, an alkali source, a template agent Q1, a template agent Q2 and a silicon source, the feeding method ensures that the silicon source and the first substances can be completely and uniformly mixed, local non-uniform mixing is not caused due to agglomeration under the condition of over alkali, and finally the silica white impurity appears.
Specifically, the preparation method uses a dual-template agent, and prepares the ZSM-12 molecular sieve with dendritic morphology by blending the alkali-silicon ratio and the mode-silicon ratio.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that the aluminum source Y is preferably at least one selected from water-soluble aluminum salt, alkali metal aluminate, aluminum alkoxide and metal aluminum.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that the aluminum source Y is preferably at least one selected from aluminum sulfate, aluminum nitrate, aluminum hydroxide, hydrated aluminum oxide and aluminum isopropoxide.
The preparation method of the ZSM-12 molecular sieve according to the invention, wherein the hydrated alumina is preferably at least one selected from boehmite, gibbsite and pseudo boehmite.
The preparation method of the ZSM-12 molecular sieve is characterized in that the silicon source X is preferably at least one selected from silicon dioxide, alkali metal silicate and tetraalkyl orthosilicate.
The preparation method of the ZSM-12 molecular sieve of the invention is characterized in that the silicon dioxide is preferably at least one selected from silicon dioxide colloid suspension, silicon dioxide precipitation and gas phase silicon dioxide, preferably, the silicon dioxide content in the silicon dioxide colloid suspension is 30-40 wt%, more preferably, the silicon source X is silica sol (the silica sol belongs to one of the silicon dioxide colloid suspensions); the alkali metal silicate is at least one selected from potassium silicate and sodium silicate.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that the inorganic base M is preferably at least one selected from sodium hydroxide, potassium hydroxide and lithium hydroxide.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that the template agent Q1 is preferably at least one selected from methyl tripropyl ammonium bromide, methyl tripropyl ammonium chloride, tetraethylammonium hydroxide and tetraethylammonium bromide.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that the template agent Q2 is preferably an organic structure directing agent, and further preferably the organic structure directing agent is at least one selected from hexamethyldiammonium chloride, N, N, N ', N' -tetramethyl-1, 4-butanediamine and tetramethyl ethylenediamine.
The preparation method of the ZSM-12 molecular sieve provided by the invention is characterized in that preferably, in the step (1), other trivalent elements Y1 are added, wherein the other trivalent elements Y1 are at least one selected from As, ti, ge, sn, fe, B, ga, be and Zn, and the molar ratio of the other trivalent elements Y1 to an aluminum source Y is 0-1.0:1 and is not 0.
The preparation method of the ZSM-12 molecular sieve according to the invention is characterized in that preferably, in the step (4), other tetravalent elements X1 are added, wherein the other tetravalent elements X1 are selected from at least one of Ge and Sn, and the molar ratio of the other tetravalent elements X1 to a silicon source X is 0-1.00:1 and is not 0.
In order to achieve the above purpose, the invention also provides a ZSM-12 molecular sieve, which is prepared by the preparation method of the ZSM-12 molecular sieve, wherein the ZSM-12 molecular sieve does not contain other crystal impurities, has the particle size range of 5-13 mu m, and has dendritic morphology.
The beneficial effects of the invention are as follows:
the preparation method of the ZSM-12 molecular sieve provided by the invention uses the easily obtained template agent, adopts a double template agent method, promotes the growth of the (1, 0) crystal face of the molecular sieve, inhibits the growth of the (0, 1, 5) crystal face, promotes the growth of ZSM-12 along the x-axis direction, and can know that the shape of the ZSM-12 molecular sieve is regulated to be a specific dendritic shape. Compared with the conventional single template agent synthesis method, the dendritic ZSM-12 molecular sieve synthesized by the method has higher double branched chain isomerization performance.
The dendritic ZSM-12 molecular sieve product obtained finally has high crystallinity and does not contain other crystal impurities. And ZSM-12 molecular sieves with different scales can be synthesized, and the scale ranges from 5 mu m to 13 mu m.
Drawings
FIG. 1 is an XRD spectrum of ZSM-12 molecular sieve obtained in example 1.
FIG. 2 is an XRD spectrum of the ZSM-12 molecular sieve obtained in example 2.
FIG. 3 is an XRD spectrum of the ZSM-12 molecular sieve obtained in comparative example 1.
FIG. 4 is a scanning electron microscope image of the ZSM-12 molecular sieve obtained in example 1.
FIG. 5 is a scanning electron microscope image of the ZSM-12 molecular sieve obtained in example 2.
FIG. 6 is a scanning electron microscope image of the ZSM-12 molecular sieve obtained in comparative example 1.
Detailed Description
The following describes embodiments of the present invention in detail: the present example is implemented on the premise of the technical scheme of the present invention, and detailed implementation modes and processes are given, but the protection scope of the present invention is not limited to the following examples, and experimental methods without specific conditions are not noted in the following examples, and generally according to conventional conditions.
The preparation method of the ZSM-12 molecular sieve provided by the invention comprises the following steps:
(1) Firstly, dissolving an aluminum source Y in water, and stirring to obtain a clear solution;
(2) Dissolving inorganic alkali M in water, stirring until the solution is clear, and then dropwise adding the clear solution in the step (1) to obtain a mixed solution;
(3) Dissolving a template agent Q1 and a template agent Q2 in water, stirring until the solution is clear, and then dropwise adding the mixed solution in the step (2);
(4) Adding a silicon source X into the mixed solution in the step (3);
(5) Adding water, uniformly mixing to obtain gel, wherein the molar ratio of H 2 O to silicon source X in the final gel is 10-35:1;
(6) Crystallizing the gel at 150-180deg.C for 10-96 hr;
(7) Washing the crystallized product with distilled water, drying at 100-120deg.C for 2-3 hr, and roasting at 300-600deg.C for 10-20 hr;
The molar ratio of each material in the synthesis mixture obtained in the step (7) is X:Y=70-150:1, M:X=0.01-0.4:1, (Q1+Q2) X=0.20-0.40:1, and Q1:Q2=1.7-2.5:1; preferably, X: y=100-130:1, m: x=0.05-0.2:1, (q1+q2): x=0.20-0.35:1, q1: q2=1.8-2.4:1.
Specifically, the template agent Q1 is a main structure guiding agent, and the cooperation of alkali metal ions and the template agent Q2 can control the crystal form of ZSM-12 to grow along a specific direction and a specific crystal face, so that the molecular sieve with a specific morphology is finally formed.
The 2 theta value A=7.28+/-0.10 and B=20.59+/-0.10 of the corresponding characteristic peaks of the molecular sieve, the corresponding crystal faces are (1, 0) and (0, 1, 5) respectively, and after the template agent Q2 is added, the molecular sieve grows along the (1, 0) crystal face and inhibits the growth of the (0, 1, 5) crystal face. When only the template Q1 was used, the relative intensity was in the range of a/b=1 to 10, and after the template Q2 was added, the relative intensity was in the range of a/b=0.1 to 0.5.
The (1, 0) crystal face of ZSM-12 intersects with the x axis, and after the template agent Q2 is added, the molecular sieve is more beneficial to growth along the x axis direction. The (0, 1, 5) crystal face is parallel to the x axis, and after the template agent Q2 is added, the growth of the crystal face can be inhibited, so that the axial diameter ratio of the molecular sieve is longer, and finally a dendritic structure is formed.
The method is characterized in that a dendritic ZSM-12 molecular sieve is used as a catalyst, n-dodecane is used as a raw material, and the conversion rate of the isomerization of the double branched chain of the product is analyzed by contacting the raw material with a bed catalyst. The specific reaction parameters are as follows: reaction temperature: 220-260 ℃ and 2-4MPa.
Specifically, in the invention, the gel is required to be configured under milder conditions, the feeding sequence is an aluminum source, an alkali source, a template agent Q1, a template agent Q2 and a silicon source, the feeding method ensures that the silicon source and the first substances can be completely and uniformly mixed, local non-uniform mixing is not caused due to agglomeration under the condition of over alkali, and finally the silica white impurity appears.
In some embodiments, it is preferred that the aluminum source Y is selected from at least one of a water-soluble aluminum salt, an alkali metal aluminate, an aluminum alkoxide, and metallic aluminum.
In some embodiments, it is preferred that the aluminum source Y is selected from at least one of aluminum sulfate, aluminum nitrate, aluminum hydroxide, hydrated aluminum oxide, aluminum isopropoxide.
In some embodiments, it is preferred that the hydrated alumina is selected from at least one of boehmite, gibbsite, and pseudo-boehmite.
In some embodiments, it is preferred that the silicon source X is selected from at least one of silica, alkali metal silicate, tetraalkylorthosilicate.
In some embodiments, it is preferred that the silica is selected from at least one of silica colloid suspension, silica precipitate, fumed silica, preferably the silica colloid suspension has a silica content of 30wt% to 40wt%, more preferably the silica source X is a silica sol (silica sol is one of silica colloid suspensions); the alkali metal silicate is at least one selected from potassium silicate and sodium silicate.
In some embodiments, it is preferable that the inorganic base M is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide.
In some embodiments, it is preferred that the templating agent Q1 is selected from at least one of methyltripropyl ammonium bromide, methyltripropyl ammonium chloride, tetraethylammonium hydroxide, tetraethylammonium bromide.
In some embodiments, it is preferred that the templating agent Q2 is an organic structure directing agent, and it is further preferred that the organic structure directing agent is selected from at least one of hexamethyldiammonium chloride, N' -tetramethyl-1, 4-butanediamine, tetramethyl ethylenediamine.
In some embodiments, it is preferred that step (1) further comprises adding an additional trivalent element Y1, said additional trivalent element Y1 being selected from at least one of As, ti, ge, sn, fe, B, ga, be and Zn, the molar ratio of the additional trivalent element Y1 to the aluminum source Y being 0-1.0:1 and not 0.
In some embodiments, it is preferred that step (4) further comprises adding another tetravalent element X1, wherein the other tetravalent element X1 is at least one selected from Ge and Sn, and the molar ratio of the other tetravalent element X1 to the silicon source X is 0-1.00:1, and is not 0.
In order to achieve the above purpose, the invention also provides a ZSM-12 molecular sieve, which is prepared by the preparation method of the ZSM-12 molecular sieve, wherein the ZSM-12 molecular sieve does not contain other crystal impurities, has the particle size range of 5-13 mu m, and has dendritic morphology.
Example 1:
(1) 0.10g NaAlO 2 was dissolved in 6g H 2 O and stirred to a clear solution.
(2) 0.17G of NaOH is dissolved in 3g H 2 O, and after being stirred into clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 2.68G of organic template Q1 methyltripropyl ammonium bromide and 0.09g of template Q2 tetramethyl ethylenediamine are dissolved in 10g H 2 O, and the solution is stirred to be a clear solution and then added dropwise to the mixed solution in the step (2).
(4) 18.5G of silica sol having a silica content of 30% was added to the mixed solution in step (3).
(5) 35.82G H 2 O was added and mixed well to give a gel.
(6) The gel obtained was crystallized at 160℃for 60h.
(7) Washing the crystallized product with distilled water, drying at 120 deg.c for 2 hr, and roasting at 300 deg.c for 20 hr.
The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.006Al2O3:0.125Na2O:0.14Q1:0.06Q2。
As shown in figure 1, the product has a structure of ZSM-12 zeolite molecular sieve A/B=1.6 belonging to MTW through X-ray diffraction analysis, and the morphology of the synthesized product can be seen to be in a dendritic structure through a scanning electron microscope photograph, the length of a trunk is about 13 mu m, a branch structure is formed, and the branch length is about 1 mu m. FIG. 4 is a Scanning Electron Microscope (SEM) photograph of ZSM-12 zeolite at this ratio.
Example 2:
(1) 0.23g NaAlO 2 was dissolved in 13.8g H 2 O and stirred to a clear solution.
(2) 0.36G of NaOH is dissolved in 6.3g H 2 O, and after stirring to be a clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 5.55G of organic template Q1 methyltripropyl ammonium bromide and 0.39g of template Q2 tetramethyl ethylenediamine are dissolved in 21g H 2 O, and the mixture in the step (2) is added dropwise after being stirred until the mixture is clear.
(4) 18.5G of silica sol having a silica content of 30% was added to the mixed solution in step (3).
(5) 4.3G of H 2 O was added and mixed well to give a gel.
(6) The gel obtained was crystallized at 160℃for 60h.
(7) The crystallized product was washed with distilled water, dried at 110℃for 3 hours, and calcined at 500℃for 15 hours.
The ratio of the reaction raw materials is as follows:
10H2O:SiO2:0.014Al2O3:0.125Na2O:0.29Q1:0.11Q2。
As shown in figure 2, the product is a ZSM-12 zeolite molecular sieve belonging to MTW in the structure through X-ray diffraction analysis, A/B=4, and the morphology of the synthesized product can be seen to show that the length of a trunk of a dendritic structure is about 5 mu m, a branch structure appears, and the branch length is about 4 mu m through a scanning electron microscope. FIG. 5 is a Scanning Electron Microscope (SEM) photograph of ZSM-12 zeolite at this ratio.
Example 3:
(1) 0.22g NaAlO 2 was dissolved in 13.2g H 2 O and stirred to a clear solution.
(2) 0.03G of NaOH is dissolved in 1g H 2 O, and after being stirred into clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 4.21G of organic template Q1 methyltripropyl ammonium bromide and 0.22g of template Q2 tetramethyl ethylenediamine are dissolved in 16g H 2 O, and the mixture solution in the step (2) is added dropwise after being stirred until the mixture solution is clear.
(4) 18.5G of silica sol having a silica content of 40% by weight was added to the mixed solution in step (3).
(5) 35.8G H 2 O is added and mixed uniformly to obtain gel.
(6) The gel obtained was crystallized at 170℃for 36h.
(7) Washing the crystallized product with distilled water, drying at 100deg.C for 3 hr, and calcining at 600deg.C for 10 hr.
The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.014Al2O3:0.01Na2O:0.22Q1:0.09Q2。
example 4:
(1) 0.13g NaAlO 2 was dissolved in 7.8g H 2 O and stirred to a clear solution.
(2) 1.22G of NaOH is dissolved in 21.5g H 2 O, and after stirring to be a clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 4.21G of organic template Q1 methyltripropyl ammonium bromide and 0.30g of template Q2 tetramethyl ethylenediamine are dissolved in 16g H 2 O, and the mixture solution in the step (2) is added dropwise after stirring until a clear solution.
(4) 18.5G of silica sol having a silica content of 30% was added to the mixed solution in step (3).
(5) 2.1G of H 2 O was added and mixed well to give a gel.
(6) The gel obtained was crystallized at 165℃for 50 hours.
(7) Washing the crystallized product with distilled water, drying at 100deg.C for 3 hr, and calcining at 600deg.C for 10 hr.
The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.008Al2O3:0.40Na2O:0.22Q1:0.12Q2。
example 5:
(1) 0.13g NaAlO 2 and 0.38g Ti (SO 4)2·9H2 O in 7.8g H 2 O) were stirred to a clear solution.
(2) 1.22G of NaOH is dissolved in 21.5g H 2 O, and after stirring to be a clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 4.21G of organic template Q1 methyltripropyl ammonium bromide and 0.30g of template Q2 tetramethyl ethylenediamine are dissolved in 16g H 2 O, and the mixture solution in the step (2) is added dropwise after being stirred until the mixture solution is clear.
(4) 18.5G of silica sol having a silica content of 30% was added to the mixed solution in step (3).
(5) 2.1G of H 2 O was added and mixed well to give a gel.
(6) The gel obtained was crystallized at 165℃for 50 hours.
(7) Washing the crystallized product with distilled water, drying at 100deg.C for 3 hr, and calcining at 600deg.C for 10 hr.
The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.008Al2O3:0.016TiO2:0.40Na2O:0.22Q1:0.12Q2.
example 6:
(1) 0.22g NaAlO 2 was dissolved in 13.2g H 2 O and stirred to a clear solution.
(2) 0.03G of NaOH is dissolved in 1g H 2 O, and after being stirred into clear solution, the clear solution in the step (1) is added dropwise to obtain a mixed solution.
(3) 4.21G of organic template Q1 methyltripropyl ammonium bromide and 0.22g of template Q2 tetramethyl ethylenediamine are dissolved in 16g H 2 O, and the mixture solution in the step (2) is added dropwise after stirring until a clear solution.
(4) 18.5G of silica sol having a silica content of 30% and 66.02g of Na 2GeO3 were added to the mixed solution in step (3).
(5) 17.2G of H 2 O was added and mixed well to obtain a gel.
(6) The gel obtained was crystallized at 170℃for 36h.
(7) Washing the crystallized product with distilled water, drying at 100deg.C for 3 hr, and calcining at 600deg.C for 10 hr.
The ratio of the reaction raw materials is as follows:
35H2O:SiO2:GeO2:0.014Al2O3:0.01Na2O:0.22Q1:0.09Q2。
Example 7:
The molecular sieves synthesized in example 3 and comparative example 1 were used as catalysts to carry out isomerization reaction on n-dodecane, and the catalysts in example 3 can improve the yield of the two-branched isomer, and specific results and reaction data are shown in table 1:
TABLE 1
Comparative example 1:
47.2g H 2O,0.13g NaAlO2 g of NaOH, 0.17g of silica sol with 30% of silicon dioxide content, 8.04g of organic template agent Q1 methyl tripropyl ammonium bromide are placed in a beaker according to the sequence of an aluminum source, an alkali source, the template agent Q1 and a silicon source to be uniformly stirred, then the gel is added into a polytetrafluoroethylene reaction kettle, crystallization is carried out at 160 ℃ for 120 hours, crystallization is complete, and a product is obtained after suction filtration and drying. The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.008Al2O3:0.125Na2O:0.42Q1。
as shown in FIG. 3, the structure of the molecular sieve is ZSM-12 zeolite molecular sieve belonging to MTW by X-ray diffraction analysis, the ratio A/B=0.4 of peak intensity, and the ratio of the axes to the diameters of the synthesized products is 2:1, the length is 1500nm, and the width is 700nm as can be seen by a scanning electron microscope photograph. FIG. 6 is a Scanning Electron Microscope (SEM) photograph of ZSM-12 zeolite synthesized at this ratio.
Comparative example 2:
47.2g H 2O,0.13g NaAlO2 g of NaOH, 0.17g of silica sol with 30% of silicon dioxide content and 0.03g of organic template agent Q2 tetramethyl ethylenediamine are placed in a beaker according to the sequence of an aluminum source, an alkali source, the template agent Q2 and a silicon source to be uniformly stirred, then the gel is added into a polytetrafluoroethylene reaction kettle, crystallization is carried out for 120 hours at 160 ℃, and the product is obtained after suction filtration and drying. The ratio of the reaction raw materials is as follows:
35H2O:SiO2:0.008Al2O3:0.125Na2O:0.03Q2。
The product obtained by X-ray diffraction analysis is amorphous silicon aluminum, and the ZSM-12 zeolite molecular sieve of MTW is not formed.
As can be seen from the comparison of the above examples and comparative examples, the preparation method of ZSM-12 molecular sieve provided by the invention uses the easily obtained template agent, adopts the double template agent method, promotes the growth of the (1, 0) crystal face of the molecular sieve, inhibits the growth of the (0, 1, 5) crystal face, promotes the growth of ZSM-12 along the x-axis direction, and can be known to regulate the shape of the ZSM-12 molecular sieve to be a specific dendritic shape. Compared with the conventional single template agent synthesis method, the dendritic ZSM-12 molecular sieve synthesized by the method has higher double branched chain isomerization performance.
Of course, the present invention is capable of other various embodiments and its several details are capable of modification and variation in light of the present invention by one skilled in the art without departing from the spirit and scope of the invention.
Claims (11)
1. The preparation method of the ZSM-12 molecular sieve is characterized by comprising the following steps of:
(1) Dissolving an aluminum source Y in water, and stirring to obtain a clear solution;
(2) Dissolving inorganic alkali M in water, stirring until the solution is clear, and then dropwise adding the clear solution in the step (1) to obtain a mixed solution;
(3) Dissolving a template agent Q1 and a template agent Q2 in water, stirring until the solution is clear, and then dropwise adding the mixed solution in the step (2);
(4) Adding a silicon source X into the mixed solution in the step (3);
(5) Adding water, uniformly mixing to obtain gel, wherein the molar ratio of H 2 O to silicon source X in the final gel is 10-35:1;
(6) Crystallizing the gel at 150-180deg.C for 10-96 hr;
(7) Washing the crystallized product with distilled water, drying at 100-120deg.C for 2-3 hr, and roasting at 300-600deg.C for 10-20 hr;
The molar ratio of each material in the synthesis mixture obtained in the step (7) is X:Y=70-150:1, M:X=0.01-0.4:1, (Q1+Q2) X=0.20-0.40:1, and Q1:Q2=1.7-2.5:1;
the template agent Q1 is at least one selected from methyl tripropyl ammonium bromide, methyl tripropyl ammonium chloride, tetraethyl ammonium hydroxide and tetraethyl ammonium bromide;
The template agent Q2 is at least one selected from hexamethyldiammonium chloride, N, N, N ', N' -tetramethyl-1, 4-butanediamine and tetramethyl ethylenediamine.
2. The method for preparing ZSM-12 molecular sieve according to claim 1, wherein the molar ratio of each material in the synthesis mixture obtained in the step (7) is X: y=100 to 130:1, m: x=0.05 to 0.2:1, (q1+q2): x=0.20 to 0.35:1, q1:q2=1.8 to 2.4:1.
3. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the aluminum source Y is selected from at least one of a water-soluble aluminum salt, an alkali metal aluminate, an aluminum alkoxide, and a metal aluminum.
4. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the aluminum source Y is at least one selected from aluminum sulfate, aluminum nitrate, aluminum hydroxide, hydrated alumina, and aluminum isopropoxide.
5. The method for preparing a ZSM-12 molecular sieve according to claim 4, wherein the hydrated alumina is at least one selected from the group consisting of boehmite, gibbsite and pseudo boehmite.
6. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the silicon source X is at least one selected from the group consisting of silica, alkali metal silicate, and tetraalkyl orthosilicate.
7. The method for preparing the ZSM-12 molecular sieve according to claim 6, wherein the silica is at least one selected from silica colloid suspension, silica precipitate and fumed silica, the silica content in the silica colloid suspension is 30wt% to 40wt%, and the silica source X is silica sol; the alkali metal silicate is at least one selected from potassium silicate and sodium silicate.
8. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the inorganic base M is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.
9. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the step (1) further comprises adding other trivalent element Y1, wherein the other trivalent element Y1 is at least one selected from As, ti, ge, sn, fe, B, ga, be and Zn, and the molar ratio of the other trivalent element Y1 to the aluminum source Y is 0-1.0:1, and is not 0.
10. The method for preparing a ZSM-12 molecular sieve according to claim 1, wherein the step (4) further comprises adding other tetravalent element X1, wherein the other tetravalent element X1 is at least one selected from Ge and Sn, and the molar ratio of the other tetravalent element X1 to the silicon source X is 0 to 1.00:1, and is not 0.
11. A ZSM-12 molecular sieve, characterized in that it is prepared by a process for preparing a ZSM-12 molecular sieve according to any of claims 1-9, said ZSM-12 molecular sieve being free of other crystalline impurities, having a particle size in the range of 5-13 μm and a dendritic morphology.
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