CN113398985A - Synthesis method of central crossed zeolite flake solid acid catalyst - Google Patents

Synthesis method of central crossed zeolite flake solid acid catalyst Download PDF

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CN113398985A
CN113398985A CN202110659485.5A CN202110659485A CN113398985A CN 113398985 A CN113398985 A CN 113398985A CN 202110659485 A CN202110659485 A CN 202110659485A CN 113398985 A CN113398985 A CN 113398985A
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zeolite
reactor
acid catalyst
solid acid
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CN113398985B (en
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周丹
王婧
夏清华
鲁新环
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Hubei University
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Abstract

The invention discloses a method for synthesizing a central crossed zeolite flake solid acid catalyst, which comprises the following steps: 1) uniformly mixing a silicon source, deionized water, a template agent, a boron source, a sodium source, a titanium source and an aluminum source to prepare reaction gel; 2) placing the reaction gel in a reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis; 3) starting the heating and rotating functions of the reactor simultaneously, so that the reaction gel is dynamically crystallized for a period of time and then statically crystallized for a period of time to obtain a crude product; 4) the crude product is subjected to simple post-treatment to obtain the solid acid catalyst. According to the invention, the zeolite flake solid acid catalyst with the center cross morphology can be prepared by a crystallization switching mode of firstly carrying out dynamic hydrothermal crystallization and then carrying out static hydrothermal crystallization, and the catalytic performance is far superior to that of a zeolite catalytic material prepared by single dynamic hydrothermal crystallization or single static hydrothermal crystallization because the zeolite flake solid acid catalyst has high external specific surface area and high exposed catalytic activity sites.

Description

Synthesis method of central crossed zeolite flake solid acid catalyst
Technical Field
The invention relates to synthesis of zeolite molecular sieve solid acid, in particular to a synthesis method of a zeolite flake solid acid catalyst with high stability, controllable thickness and central cross morphology.
Background
The zeolite molecular sieve is an important microporous crystal material (the pore size is less than or equal to 2nm), is widely applied to the fields of adsorption, separation, catalysis, energy storage and the like, and plays an extremely important strategic position in national economy. However, the catalytic application of the zeolite molecular sieve is still mainly limited to the catalytic conversion of small organic molecules, because the microporous structure is not favorable for the diffusion of large substrate molecules, mass transfer, formation of intermediate transition states and the like.
Two-dimensional zeolite flakes have the advantage of a high external specific surface area compared to three-dimensional zeolite molecular sieve particles because their crystal growth in one dimension is limited, which makes the catalytically active sites distributed on the flakes more accessible to substrate molecules (especially large substrate molecules) to promote the reaction, and has attracted considerable research interest in recent years. The reported zeolite flakes are generally prepared by means of post-treatments such as layer exfoliation, interlayer expansion, and the like. However, the method of post-treatment has many problems, for example, it is difficult to ensure the uniformity of the resulting zeolite flakes, i.e., the thickness of the zeolite flakes is difficult to control; zeolite flakes are generally less stable because the surface of the zeolite flakes typically contains a large number of hydroxyl groups, which are susceptible to condensation polymerization after multiple catalytic reactions, thereby causing sheet-to-sheet blocking. The above problems greatly affect the catalytic performance of such catalytic materials. Therefore, it is highly desirable to prepare homogeneous zeolite flake catalytic materials having high stability.
Disclosure of Invention
The invention aims to solve the defects of the background technology and provide a synthesis method of a central crossed zeolite flake solid acid catalyst with high stability and controllable thickness. The method can synthesize the central crossed zeolite sheet with high stability and controllable thickness by controlling the zeolite crystallization process, namely adopting a switching crystallization mode of firstly carrying out dynamic hydrothermal crystallization and then carrying out static hydrothermal crystallization, and then obtaining the central crossed zeolite sheet solid acid catalyst by simple post-treatment.
The technical scheme of the invention is as follows: a method for synthesizing a central crossed zeolite flake solid acid catalyst with high stability and controllable thickness is characterized by comprising the following steps:
1) uniformly mixing raw materials to prepare reaction gel, wherein the raw materials comprise the following materials in parts by mole:
Figure BDA0003107026070000021
the silicon source is made of SiO2Metering the boron source with B2O3The sodium source is counted as Na2Calculated by O, the aluminum source is Al2O3The titanium source is calculated as TiO2Counting;
2) placing the reaction gel in a reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis;
3) heating the interior of the reactor, keeping the temperature, and simultaneously rotating the reactor around a horizontal axis at a rotation rate of 56-200 rpm for 2-15 h from the heating moment so as to perform dynamic hydrothermal crystallization on the reaction gel; after stopping rotating, keeping the reactor at a constant temperature and standing, and performing static hydrothermal crystallization on reaction gel to obtain a crude product;
4) and filtering, washing, drying and acid-treating the crude product or loading, filtering, washing, drying and roasting the crude product to obtain the zeolite flake solid acid catalyst with the central cross morphology.
Preferably, the heating temperature of the reactor in the step 3) is 60-200 ℃, and the heat preservation and standing time of the reactor is 36-360 h.
Further, in the step 3), the reactor is heated to 160-180 ℃ and then is subjected to heat preservation, the rotation time is 10-12 hours, the rotation speed is 120-170 rpm, and the heat preservation rest time of the reactor is 240-360 hours.
Furthermore, in the step 3), the temperature of the reactor is maintained after the reactor is heated to 170 ℃, the rotation time is 12h, the rotation speed is 140rpm, and the temperature-maintaining standing time of the reactor is 240 h.
Preferably, the silicon source in step 1) is one or more of fumed silica, ethyl orthosilicate, silica sol, white carbon black and water glass.
Preferably, the template in step 1) is piperidine, hexamethyleneimine, tetrabutylphosphine oxide, N-methylpyrrolidone, 3- (trimethoxy silane) propylhexadecyl dimethyl ammonium chloride, N-hexadecyl-N-methyl-triethylene diamine, hexamethyleneimine, 3- (trimethoxy silane) propyloctadecyl dimethyl ammonium chloride, Zn (NO)3)2·6H2One or more of O.
Preferably, the boron source in step 1) is boric acid and/or borate, and the sodium source is sodium hydroxide.
Preferably, the titanium source in step 1) is one or more of n-butyl titanate, tetraalkyl titanate and titanium halide, and the aluminum source is one or more of sodium metaaluminate, aluminum isopropoxide and aluminum hydroxide.
Preferably, the reactor in the step 2) is an oven with a horizontal rotating shaft.
Preferably, the method comprises the following steps:
1) uniformly mixing raw materials to prepare reaction gel, wherein the raw materials comprise the following materials in parts by mole: 1.0 part of silicon source, removing25 parts of ionized water, 1.5 parts of template agent, 0.67 part of boron source and 0.037 part of titanium source, wherein the silicon source is SiO2Metering the boron source with B2O3The titanium source is calculated as TiO2Counting;
2) placing the reaction gel in a reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis;
3) heating the interior of the reactor to 170 ℃, then preserving heat, and simultaneously starting the reactor to rotate around a horizontal axis for 12 hours from the heating moment at a rotation speed of 140rpm so as to perform dynamic hydrothermal crystallization on the reaction gel; after stopping rotating, keeping the temperature of the reactor and standing for 240 hours to perform static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) and filtering, washing, drying and acid treating the crude product or loading, filtering, washing, drying and roasting the crude product to obtain the central crossed zeolite flake solid acid catalyst.
The rotation speed and the rotation time during the dynamic hydrothermal crystallization, the sequence of the dynamic crystallization and the static hydrothermal crystallization time are all very critical:
the rotation speed is too high, the centrifugal force of the reaction kettle is too high, and reaction gel is gathered at the corner of the kettle wall and cannot be fully and uniformly mixed; too low a rate is not conducive to sufficiently uniform mixing of the reaction gel.
Too long a rotational crystallization time can result in changes in the morphology of the final product that do not result in zeolite flakes having a central cross-morphology. The rotating hydrothermal crystallization time cannot be too long, and must be limited to the crystal nucleation stage, and the time of the crystal nucleation stage has a certain relationship with the rotating speed. If the rotation crystallization time is too long and exceeds the crystal nucleation stage, crystal growth occurs at the moment, and the rotation hydrothermal condition can cause a growth mode of crystal cross symbiosis, so that disordered aggregates of zeolite sheets are obtained, and the central crossed zeolite sheets cannot be obtained. Too short a rotational crystallization time may result in a change in the morphology of the final product that does not result in zeolite flakes having a central cross-morphology. The long standing crystallization time is unnecessary, energy is wasted, and the zeolite crystallization is incomplete when the time is too short.
The order of dynamic state and static state is very critical during crystallization: the crystallization sequence of first dynamic and then static has a decisive effect on the formation of the central crossed zeolite sheets; if the order is reversed, namely static crystallization is carried out firstly and then dynamic crystallization is carried out, and the central crossed zeolite sheet cannot be obtained.
The dynamic crystallization in the invention adopts rotation around a horizontal rotating shaft, which is completely different from the stirring in the prior art: stirring in the prior art means that a stirring blade or a stirring paddle is arranged in a reaction kettle, the stirring blade or the stirring paddle is directly contacted with reaction gel in the crystallization process, the reaction gel is stirred through the mechanical motion of the stirring blade or the stirring paddle to realize dynamic crystallization, and the stirring direction is disordered. The crystallization reaction kettle used in the invention is not provided with any stirring blade or stirring paddle, and is not additionally provided with any object serving as a stirrer and the like, the reaction kettle is fixed on the horizontal rotating shaft by a fixing ring outside the reaction kettle, reaction gel inside the reaction kettle rolls and rotates along with a naturally generated centrifugal force in the process of rotating around the horizontal rotating shaft, and the direction of the centrifugal force is directed to the horizontal rotating shaft, namely the same direction, so that the crystallization kettle is beneficial to self-assembling of the crystal seeds into the crystal seed aggregate with certain orientation through high-frequency collision, which is completely different from the stirring dynamic crystallization in the prior art. The invention adopts a switching crystallization mode of firstly dynamic hydrothermal crystallization and then static hydrothermal crystallization to prepare the center crossed zeolite sheet solid acid catalyst according to the following principle: the seed crystal prepared under the dynamic hydrothermal condition has certain orientation, namely the tiny seed crystal is aggregated into a seed crystal aggregate with certain orientation under the dynamic hydrothermal high-frequency collision environment; under the subsequent static hydrothermal conditions, crystal growth proceeds along the crystal seed aggregates with orientation, so as to finally obtain the crude product of the central crossed zeolite flakes.
Unlike the zeolite flake solid acid catalytic material with stripped layers, the center crossed zeolite flake solid acid catalyst has high structural stability, and even if catalytic reaction is carried out for many times, the hydroxyl on the surface of the zeolite flake can not be adhered. After multiple catalytic reactions, the interlayer of the zeolite sheet catalytic material obtained by the interlayer expansion method is easily blocked by organic substrate molecules, so that the catalytic performance of the zeolite sheet catalytic material is influenced; the central crossed zeolite sheet catalytic material can still maintain excellent catalytic performance after multiple catalytic reactions.
The thickness of the zeolite flakes is related to the static crystallization time. The thickness of the zeolite sheet can be increased by properly prolonging the static crystallization time. Therefore, the thickness of the zeolite flake can be controlled by regulating and controlling the static crystallization time, and the center cross zeolite flake solid acid catalyst with good uniformity and high stability is obtained.
The invention has the beneficial effects that:
1. the zeolite sheet catalytic material with crossed centers is synthesized by adopting a switching crystallization mode of firstly dynamic hydrothermal crystallization and then static hydrothermal crystallization, the zeolite sheet has high external specific surface area and high exposed catalytic activity sites, and compared with a zeolite molecular sieve prepared by single dynamic hydrothermal crystallization or single static hydrothermal crystallization, the external specific surface area of the zeolite sheet catalytic material prepared by the method is increased by more than 30%, so that the catalytic activity of the catalyst is improved.
2. The order of dynamic crystallization first and static crystallization second is very critical. If the order is reversed, namely static crystallization is carried out firstly and then dynamic crystallization is carried out, the central crossed zeolite sheet catalytic material cannot be obtained.
3. The central cross zeolite flake solid acid catalyst prepared by the invention has excellent structural stability and chemical stability, and can still keep good physical and chemical properties in multiple catalytic reaction-circulation.
4. The thickness of the zeolite flakes is related to the static crystallization time. The thickness of the zeolite flake can be controlled by regulating and controlling the static crystallization time, and the center cross zeolite flake solid acid catalyst with good uniformity and high stability is obtained.
5. Simple synthesis process, easy operation, good reproducibility, low cost and environmental protection.
Drawings
FIG. 1 is an XRD pattern of a central crossed zeolite flake solid acid catalyst prepared in example 2;
FIG. 2 is a transmission electron micrograph of a center crossed zeolite flake solid acid catalyst prepared in example 2;
FIG. 3 is a transmission electron micrograph of the central crossed zeolite flake solid acid catalyst prepared in example 2 after 7 times of catalytic condensation reaction of benzaldehyde and ethylene glycol;
FIG. 4 is a scanning electron micrograph of the zeolitic material obtained in comparative example 1;
fig. 5 is a scanning electron micrograph of the zeolite material prepared in comparative example 2.
Detailed Description
The present invention is further illustrated in detail in the following specific examples (in the following examples, the silicon source is SiO2Metering boron source as B2O3The sodium source is calculated as Na2Calculated by O, the aluminum source is Al2O3The titanium source is calculated as TiO2Meter).
Example 1
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 3.0g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 0.6g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:0.5:0.07:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 2
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained above under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:1.5:0.67:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst. The XRD pattern is shown in figure 1.
Example 3
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 11.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 8.7g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:2:1:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 4
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 10.1g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 2.3g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 8.7g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:8:1.5:1: 0.1;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 5
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 50.4g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; adding 0.3g of ground aluminum isopropoxide into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 20 hours; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the obtained mixed solution under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar weight ratio of the silicon source, the deionized water, the template agent, the boron source and the aluminum source is 1:40:1.5:0.67:0.01 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 110rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished to perform static hydrothermal crystallization on the reaction gel, and obtaining a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 6
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 75.6g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; adding 0.3g of ground aluminum hydroxide into the mixed solution obtained in the step under the stirring condition, and continuing stirring for 20 hours; dissolving 0.6g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained in the previous step under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source to the deionized water to the template to the boron source to the aluminum source is 1:60:1.5:0.07:0.027 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 110rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 240 hours after the rotation is finished to perform static hydrothermal crystallization on the reaction gel, and obtaining a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 7
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained above under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:1.5:0.67:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 160 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 10 hours from the heating moment at the rotating speed of 120rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 360 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 8
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained above under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:1.5:0.67:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 180 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 11 hours from the heating moment at the rotating speed of 150rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 300 hours after the rotation is finished to perform static hydrothermal crystallization on the reaction gel, and obtaining a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 9
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained above under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:1.5:0.67:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, then preserving heat, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 300 hours after the rotation is finished to perform static hydrothermal crystallization on the reaction gel, and obtaining a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 10
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 31.5g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; slowly dripping 0.9g of tetrabutyl titanate into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution obtained above under the stirring condition, and continuing stirring for 2 hours until a gel solution is formed, wherein the molar ratio of the silicon source, the deionized water, the template agent, the boron source and the titanium source is 1:25:1.5:0.67:0.037 in the embodiment;
2) transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 170 ℃, keeping the temperature, simultaneously rotating the reactor around a horizontal axis for 12 hours from the heating moment at the rotating speed of 140rpm to perform dynamic hydrothermal crystallization on the reaction gel, keeping the temperature of the reactor static for 360 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 11
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 50.4g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; adding 2.9g of ground aluminum isopropoxide into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 20 hours; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution under the stirring condition, and continuously stirring for 2 hours until a gel solution is formed; in this example, the molar weight ratio of the silicon source, the deionized water, the templating agent, the boron source, and the aluminum source is 1:40:1.5:0.67: 0.1.
2) Transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 60 ℃, then preserving heat, simultaneously rotating the reactor for 2 hours around a horizontal axis from the heating moment at the rotating speed of 56rpm to perform dynamic hydrothermal crystallization on the reaction gel, preserving heat and standing the reactor for 36 hours after the rotation is finished to perform static hydrothermal crystallization on the reaction gel, and obtaining a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Example 12
The synthesis method of the central crossed zeolite flake solid acid catalyst provided by the embodiment comprises the following steps:
1) adding 8.9g of piperidine into 50.4g of deionized water, and uniformly stirring at room temperature to obtain a mixed solution; adding 2.9g of ground aluminum isopropoxide into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 20 hours; dissolving 5.8g of boric acid into the mixed solution obtained in the step under the stirring condition, and continuously stirring for 1 hour; slowly adding 4.2g of silicon dioxide into the mixed solution under the stirring condition, and continuously stirring for 2 hours until a gel solution is formed; in this example, the molar weight ratio of the silicon source, the deionized water, the templating agent, the boron source, and the aluminum source is 1:40:1.5:0.67: 0.1.
2) Transferring the prepared reaction gel into a high-pressure reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis (the reactor in the embodiment is an oven with a horizontal rotating shaft);
3) heating the inside of the reactor to 200 ℃, keeping the temperature, simultaneously rotating the reactor around a horizontal axis for 15 hours from the heating moment at the rotating speed of 200rpm to perform dynamic hydrothermal crystallization on the reaction gel, keeping the temperature of the reactor static for 360 hours after the rotation is finished, and performing static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) filtering the crude product, washing with water, drying in an oven at 80 ℃ for 12h, and performing acid treatment, wherein the acid treatment specifically comprises the following steps: acid washing with 2mol/l nitric acid solution at 80 ℃ for 20h, filtering the obtained solution, washing with water, and drying in an oven at 80 ℃ for 20h to obtain the crossed-center zeolite sheet solid acid catalyst.
Comparative example 1
Comparative example 1 and example 2 differ only in that: and 3) statically crystallizing the reaction kettle filled with the reaction gel at the same temperature for 252 hours without dynamic crystallization. As shown in fig. 4, the obtained product showed flower-like morphology, which is completely different from the plug-in card structure of the central crossed zeolite flake solid acid catalyst of the present invention.
Comparative example 2
Comparative example 2 and example 2 differ only in that: and 3) dynamically crystallizing the reaction kettle filled with the reaction gel at the same temperature and the rotating speed of 56rpm for 84 hours without static crystallization. As shown in FIG. 5, the obtained product has a hollow nest-like appearance, which is completely different from the plug-in card structure of the central crossed zeolite flake solid acid catalyst in the invention.
Performance testing
As can be seen from fig. 1, the central crossed zeolite flake material produced by the process of the present invention has a fully crystallized MWW topology.
It can be seen from fig. 2 that the lamellae of the central crossed zeolite flake material prepared by the present invention are staggered with each other to form a central plug-in card shape; after the central crossed zeolite flake catalyst obtained in example 2 participates in a condensation reaction of benzaldehyde and ethylene glycol (under the reaction conditions of 25mg of the catalyst, 6ml of cyclohexane, 5mmol of benzaldehyde, 7.5mmol of ethylene glycol, 5 hours of reaction time and 90 ℃), the shape of the central crossed zeolite flake catalyst is shown in figure 3, and the central crossed zeolite flake catalyst still has the shape characteristics of central crossing, so that the central crossed zeolite flake material has excellent structural stability; the physical parameters of the catalyst which participate in the condensation reaction of benzaldehyde and ethylene glycol in multiple cycles are shown in the following table 1, and it can be known that the physical parameters of the catalyst are not obviously changed after multiple reactions, and the material prepared by the invention has excellent structural stability.
In examples 2, 9, and 10, the thickness of the obtained zeolite flakes with the central cross morphology was about 1.8-2.0 nm, 2.1-2.3 nm, and 2.4-2.6 nm, respectively, only by changing the static crystallization time, i.e., by performing static crystallization for 240h, 300h, and 360h, respectively.
TABLE 1 solid acid catalyst of crossed-center zeolite flakes obtained in example 2 catalyzed the condensation reaction between benzaldehyde and ethylene glycol and the physical parameters of the samples before and after the catalyzed reaction
Figure BDA0003107026070000161
TABLE 2 results of solid acid catalysis of benzaldehyde condensation with ethylene glycol by the crossed-center zeolite flakes obtained in examples 1-10
Catalyst and process for preparing same Conversion ratio of benzaldehyde in condensation reaction of benzaldehyde and ethylene glycol (%)
Example 1 61.51
Example 2 63.28
Example 3 62.34
Example 4 62.68
Example 5 63.07
Example 6 61.98
Example 7 63.29
Example 8 62.94
Example 9 62.45
Example 10 62.69
Example 11 60.23
Example 12 60.78
The product obtained in comparative example 1 is referred to as comparative catalyst I, the product obtained in comparative example 2 is referred to as catalyst II, and the comparative catalyst I and the comparative catalyst II participate in the condensation reaction of benzaldehyde and ethylene glycol in the same molar amount as the catalyst obtained in the present invention, and the performance of the catalyst obtained in the present invention is shown in Table 3 below. As can be seen from Table 3, the zeolite flake catalyst of the present invention has an increased external specific surface area by 30% or more and an improved conversion by 14.95% or more.
TABLE 3 comparison of catalytic Properties
Figure BDA0003107026070000171

Claims (10)

1. A method for synthesizing a center crossed zeolite flake solid acid catalyst is characterized by comprising the following steps:
1) uniformly mixing raw materials to prepare reaction gel, wherein the raw materials comprise the following materials in parts by mole:
Figure FDA0003107026060000011
the silicon source is made of SiO2Metering the boron source with B2O3The sodium source is counted as Na2Calculated by O, the aluminum source is Al2O3The titanium source is calculated as TiO2Counting;
2) placing the reaction gel in a reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis;
3) heating the interior of the reactor, keeping the temperature, and simultaneously rotating the reactor around a horizontal axis at a rotation rate of 56-200 rpm for 2-15 h from the heating moment so as to perform dynamic hydrothermal crystallization on the reaction gel; after stopping rotating, keeping the reactor at a constant temperature and standing, and performing static hydrothermal crystallization on reaction gel to obtain a crude product;
4) and filtering, washing, drying and acid-treating the crude product or loading, filtering, washing, drying and roasting the crude product to obtain the zeolite flake solid acid catalyst with the central cross morphology.
2. The method for synthesizing the high-stability central crossed zeolite flake solid acid catalyst with controllable thickness according to claim 1, wherein the heating temperature of the reactor in the step 3) is 60-200 ℃, and the holding time of the reactor is 36-360 h.
3. The method for synthesizing the crossed-center zeolite flake solid acid catalyst as claimed in claim 2, wherein the reactor in the step 3) is heated to 160-180 ℃ and then is kept warm, the rotation time is 10-12 h, the rotation speed is 120-170 rpm, and the reactor is kept warm and is kept still for 240-360 h.
4. The method for synthesizing a crossed-center zeolite flake solid acid catalyst as claimed in claim 3, wherein the reactor in step 3) is heated to 170 ℃ and then is maintained at the temperature, the rotation time is 12h, the rotation speed is 140rpm, and the reactor is maintained at the stationary time for 240 h.
5. The method for synthesizing the crossed-center zeolite flake solid acid catalyst as claimed in claim 1, wherein the silicon source in step 1) is one or more of fumed silica, ethyl orthosilicate, silica sol, white carbon black and water glass.
6. The method of claim 1, wherein the template in step 1) is piperidine, hexamethyleneimine, tetrabutyl phosphine oxide, N-methylpyrrolidone, 3- (trimethoxy silane) propylhexadecyldimethyl ammonium chloride, N-hexadecyl-N-methyl-triethylene diamine, hexamethyleneimine, 3- (trimethoxy silane) propyloctadecyl dimethyl ammonium chloride, Zn (NO) is3)2·6H2One or more of O.
7. The method for synthesizing a crossed-center zeolite flake solid acid catalyst as claimed in claim 1, wherein the boron source in step 1) is boric acid and/or a borate salt and the sodium source is sodium hydroxide.
8. The method for synthesizing the crossed central zeolite flake solid acid catalyst as claimed in claim 1, wherein the titanium source in step 1) is one or more of n-butyl titanate, tetraalkyl titanate and titanium halide, and the aluminum source is one or more of sodium metaaluminate, aluminum isopropoxide and aluminum hydroxide.
9. The method for synthesizing a crossed-center zeolite flake solid acid catalyst as claimed in claim 1, wherein the reactor in step 2) is an oven with a horizontal rotating shaft.
10. The method of synthesizing a crossed-center zeolite flake solid acid catalyst of claim 1 comprising the steps of:
1) uniformly mixing raw materials to prepare reaction gel, wherein the raw materials comprise the following materials in parts by mole: 1.0 part of silicon source, 25 parts of deionized water, 1.5 parts of template agent, 0.67 part of boron source and 0.037 part of titanium source, wherein the silicon source is SiO2Metering the boron sourceB2O3The titanium source is calculated as TiO2Counting;
2) placing the reaction gel in a reaction kettle, sealing the reaction kettle, and fixing the reaction kettle in a reactor which has a heating function and can rotate around a horizontal axis;
3) heating the interior of the reactor to 170 ℃, then preserving heat, and simultaneously starting the reactor to rotate around a horizontal axis for 12 hours from the heating moment at a rotation speed of 140rpm so as to perform dynamic hydrothermal crystallization on the reaction gel; after stopping rotating, keeping the temperature of the reactor and standing for 240 hours to perform static hydrothermal crystallization on the reaction gel to obtain a crude product;
4) and filtering, washing, drying and acid treating the crude product or loading, filtering, washing, drying and roasting the crude product to obtain the central crossed zeolite flake solid acid catalyst.
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Publication number Priority date Publication date Assignee Title
CN102241407A (en) * 2011-04-29 2011-11-16 大连理工大学 Preparation method of SUZ-4 molecular sieve
CN105645430A (en) * 2016-02-25 2016-06-08 湖北大学 Crystal-seed method for rapidly synthesizing Ti-MWW molecular sieves through rotation
CN108975352A (en) * 2018-10-23 2018-12-11 福州大学 A kind of preparation method of nano pure silicone ZSM-5 zeolite
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