CN110217804B

CN110217804B - ZSM-5 molecular sieve and preparation method thereof, hydrogen type ZSM-5 molecular sieve and application thereof, and methanol conversion method

Info

Publication number: CN110217804B
Application number: CN201810170630.1A
Authority: CN
Inventors: 邢爱华; 缪平; 桑宇
Original assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Current assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Priority date: 2018-03-01
Filing date: 2018-03-01
Publication date: 2021-01-22
Anticipated expiration: 2038-03-01
Also published as: CN110217804A

Abstract

The invention relates to the field of molecular sieves used for preparing olefin catalysts by methanol conversion, and discloses a ZSM-5 molecular sieve and a preparation method thereof, a hydrogen type ZSM-5 molecular sieve and application thereof, and a methanol conversion method, wherein the preparation method comprises the following steps: (1) mixing a first silicon source, a first aluminum source, a first alkali source, a first template agent, seed crystals, urea and water, and then aging to obtain gel; (2) sequentially carrying out low-temperature crystallization and high-temperature crystallization on the gel; (3) drying and roasting the solid product obtained by high-temperature crystallization in the step (2); the low-temperature crystallization temperature is 90-130 ℃, the high-temperature crystallization temperature is 150-180 ℃, the seed crystal is a spherical ZSM-5 molecular sieve containing a second template agent, and the seed crystal is obtained by crystallization at the temperature of 100-135 ℃. The molecular sieve provided by the invention has low production cost, can be used for preparing olefin by converting methanol, can improve the selectivity of propylene and butylene, and has longer service life.

Description

ZSM-5 molecular sieve and preparation method thereof, hydrogen type ZSM-5 molecular sieve and application thereof, and methanol conversion method

Technical Field

The invention relates to the field of molecular sieves used for preparing olefin catalysts through methanol conversion, in particular to a ZSM-5 molecular sieve and a preparation method thereof, and also relates to a hydrogen type ZSM-5 molecular sieve and application thereof, and the invention further relates to a methanol conversion method.

Background

Coal or natural gas is used as a raw material to synthesize methanol through synthesis gas, low-carbon olefin can be efficiently prepared through the methanol, a new raw material route is found for olefin production, and the energy crisis caused by the problem of petroleum and natural gas resources is greatly relieved. Propylene is an important organic chemical raw material, and with the rapid increase in the demand for derivatives such as polypropylene, the demand for the raw material propylene has also increased year by year. The carbon four-hydrocarbon has long been used as the main component of liquefied gas and is consumed as civil fuel. The chemical utilization rate of four carbon components in China is less than 40 percent, while the chemical utilization rate of four carbon components in the United states, Japan and Western Europe is up to more than 70 percent, and with the progress of separation technology, the application of four carbon components as chemical raw materials is developed rapidly. It is predicted that the carbon four component will be a high value petrochemical feedstock following ethylene and propylene. Therefore, the MTPB process for producing more butylene and propylene by methanol is a new chemical technology for preparing olefin by methanol by taking coal as a raw material after the MTO process for preparing ethylene and propylene by methanol and the MTP process for preparing propylene by methanol. One of the core technologies for preparing propylene and butylene through methanol conversion is a catalyst, and the properties and performance of the catalyst determine the development direction of a new process technology for preparing propylene and butylene through methanol conversion.

The ZSM-5 molecular sieve has stronger acidity, excellent shape selectivity and good hydrothermal stability, so that the ZSM-5 molecular sieve becomes a main active component for preparing propylene and butylene (MTPB) from methanol and has higher catalytic activity. However, the pure microporous structure and large particle size of the ZSM-5 molecular sieve result in that methanol molecules are not easy to contact the reaction center, products are not easy to diffuse, the acid distribution is not uniform, a large amount of non-target products are easily generated, and carbon deposition is rapidly generated to shorten the service life of the catalyst, so that the application of the ZSM-5 molecular sieve in the MTPB reaction is limited. The nanocrystallization of the ZSM-5 molecular sieve is beneficial to improving the mass transfer property and adjusting the acid property of the ZSM-5 molecular sieve, and the catalytic property of the ZSM-5 molecular sieve in the MTPB reaction is improved. The nanocrystallization of the ZSM-5 molecular sieve is beneficial to improving the mass transfer property and adjusting the acid property of the ZSM-5 molecular sieve, and the catalytic property of the ZSM-5 molecular sieve in the MTPB reaction is improved.

At present, there are various methods for synthesizing a nano-sized ZSM-5 molecular sieve, such as a seed crystal method, a solid-solid conversion method, a special solvent state method, a special template method, a special silicon source method, a special additive method, a low temperature crystallization method, etc., wherein the seed crystal method is one of the most commonly used and effective methods. The general steps of the seed crystal synthesis include: (1) preparing crystallized gel: calculating the adding amount of the raw materials according to a certain material proportioning relation, and mixing the template agent, water, sodium hydroxide, an aluminum source, a silicon source, seed crystals and urea according to a certain adding sequence; (2) aging; (3) and (3) crystallization: the temperature of the crystallization kettle is raised to 150 ℃ and 180 ℃, and the temperature is kept constant for a certain time under the autogenous pressure.

CN102874843A discloses a method for preparing a nano-scale ZSM-5 molecular sieve by a seed crystal method. The method is characterized by uniformly mixing aluminum isopropoxide, ethyl orthosilicate, tetrapropylammonium hydroxide and water, stirring and aging, drying the aged sol-gel into dry gel, grinding the dry gel into powdery dry gel powder serving as dry gel seed crystals, mixing the water, a silicon source, an aluminum source and the dry gel seed crystals, uniformly stirring, and statically crystallizing the mixture in a reaction kettle to obtain the nanoscale ZSM-5 molecular sieve.

CN102666385A discloses a method for preparing a nano-scale ZSM-5 molecular sieve by a seed crystal method. The method is characterized in that water glass and water are mixed for a certain time to obtain A, aluminum sulfate, sulfuric acid, water and seed crystal are mixed for a certain time to obtain B, then the A and the B are mixed, and hydrothermal crystallization is carried out for 24 hours at 170 ℃ to obtain the nano-scale ZSM-5 molecular sieve.

CN101983921A discloses a method for preparing a nano-scale ZSM-5 molecular sieve by a seed crystal method. The invention is characterized in that NaOH, silica sol and water are prepared into A, KF.2H is prepared₂Preparing B from O and water, preparing C from TPABr and water, and preparing D from aluminum sulfate, water and sodium sulfate. D was added slowly to A with stirring, followed by B and C, and stirred for 15 minutes. Then adding seed crystal, stirring and aging for 4 hours, and crystallizing for 20-30 hours at the temperature of 180 ℃ in a high-pressure stainless steel reaction kettle to obtain the nano-scale ZSM-5 molecular sieve.

Although the above methods can prepare the nanometer-sized ZSM-5 molecular sieve, there are many disadvantages, such as (1) the preparation process of the molecular sieve is complicated: CN102874843A needs to prepare dry glue powder, and CN101983921A needs to prepare a plurality of mixtures; (2) there is still a need to further reduce the size of the molecular sieves produced; (3) there is still a need to further improve the selectivity of catalysts for the conversion of methanol to propylene and butene.

Disclosure of Invention

The invention aims to overcome the defects that the preparation process of a ZSM-5 molecular sieve is complicated, the size of the prepared ZSM-5 molecular sieve is overlarge, and a catalyst for preparing propylene and butylene through methanol conversion has low selectivity and short service life, and provides the ZSM-5 molecular sieve, a preparation method thereof, a hydrogen type ZSM-5 molecular sieve, application thereof and a methanol conversion method.

The inventor of the invention discovers in the research process that the ZSM-5 molecular sieve with the nano-scale in the three axial directions of a, b and c can be obtained by selecting the spherical ZSM-5 molecular sieve which is obtained by low-temperature crystallization and contains the template agent as the seed crystal, adding urea into the prepared initial gel, aging for a certain time, and then carrying out low-temperature crystallization (90-130 ℃) and high-temperature crystallization (150-180 ℃); moreover, the ZSM-5 molecular sieve prepared by the method is converted into a hydrogen type molecular sieve by ion exchange and then used as a catalyst, and shows longer service life and higher selectivity. The present invention has been completed based on this finding.

According to a first aspect of the present invention, there is provided a process for the preparation of a ZSM-5 molecular sieve, the process comprising:

(1) mixing a first silicon source, a first aluminum source, a first alkali source, a first template agent, seed crystals, urea and water, and then aging to obtain gel;

(2) sequentially carrying out low-temperature crystallization and high-temperature crystallization on the gel;

(3) drying and roasting the solid product obtained by high-temperature crystallization in the step (2);

the low-temperature crystallization temperature is 90-130 ℃, the high-temperature crystallization temperature is 150-180 ℃, the seed crystal is a spherical ZSM-5 molecular sieve containing a second template agent, and the seed crystal is obtained by crystallization at the temperature of 100-135 ℃.

According to a second aspect of the present invention, there is provided a ZSM-5 molecular sieve produced by the preparation method of the present invention.

According to a third aspect of the present invention, there is provided a hydrogen form of the ZSM-5 molecular sieve, the hydrogen form of the ZSM-5 molecular sieve material being formed by ion exchange of the ZSM-5 molecular sieve provided by the present invention.

According to a fourth aspect of the invention, the invention provides an application of the hydrogen type ZSM-5 molecular sieve in the preparation of propylene and butylene through methanol conversion reaction.

According to a fifth aspect of the present invention, there is provided a method for producing propylene and butene by methanol conversion, the method comprising contacting methanol with the hydrogen type ZSM-5 molecular sieve provided by the present invention under the reaction conditions for producing propylene and butene by methanol conversion.

The invention provides a method for preparing propylene and butylene by methanol conversion, which comprises the step of contacting methanol with a hydrogen type ZSM-5 molecular sieve under the reaction condition of preparing the propylene and the butylene by the methanol conversion,

the hydrogen type ZSM-5 molecular sieve is prepared by the following steps:

(I) mixing a second silicon source, a second aluminum source, a second alkali source, a second template agent and water, sequentially performing second ageing and crystallization, and performing second drying on a solid product obtained by crystallization to obtain a spherical ZSM-5 molecular sieve containing the second template agent as a seed crystal;

wherein the molar ratio of the second silicon source, the second aluminum source, the second alkali source, the second template agent and the water is 100: (0.2-2): (1-10): (5-25): (1000-2000), wherein the second silicon source is SiO₂The second aluminum source is calculated as Al₂O₃The second alkali source is calculated by oxide;

the crystallization conditions include: the temperature is 100-135 ℃, the time is 24-96h,

(II) mixing a first silicon source, a first aluminum source, a first alkali source, a first template agent, the seed crystal, urea and water, and then aging to obtain gel;

(III) sequentially carrying out low-temperature crystallization and high-temperature crystallization on the gel; the low-temperature crystallization temperature is 90-130 ℃, and the high-temperature crystallization temperature is 150-180 ℃;

(IV) drying and roasting the solid product obtained by high-temperature crystallization in the step (III) to obtain the ZSM-5 molecular sieve;

(V) carrying out ion exchange on the ZSM-5 molecular sieve to obtain the hydrogen type ZSM-5 molecular sieve.

The invention has the following advantages:

(1) the addition of the seed crystal (the spherical ZSM-5 molecular sieve containing the second template) reduces the dosage of the first template and reduces the production cost;

(2) the spherical ZSM-5 molecular sieve crystallized and synthesized at lower temperature (100-135 ℃) is used as the seed crystal, and has higher product selectivity and longer service life than the ZSM-5 molecular sieve synthesized by using the sheet ZSM-5 molecular sieve as the seed crystal;

(3) the addition of urea (inhibitor) is more beneficial to the formation of a sheet ZSM-5 molecular sieve and the mass transfer in the methanol conversion process;

(4) compared with the crystallization at high temperature and constant temperature, the temperature-variable crystallization process of low temperature and high temperature is adopted in the invention, which is more favorable for improving the catalytic performance of the prepared molecular sieve;

(5) the ZSM-5 molecular sieve provided by the invention has smaller size, is beneficial to the diffusion of products such as propylene, butylene and the like, inhibits the side reactions such as hydrogen transfer, oligomerization, cyclization, aromatization and the like of olefin, and improves the selectivity of propylene and butylene;

(6) the preparation method of the ZSM-5 molecular sieve provided by the invention is simple in process flow, easy to implement and suitable for large-scale production.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) photograph of a seed crystal J-1 obtained in production example 1, and FIGS. 1a and 1b are SEM photographs of the seed crystal J-1 at different magnifications;

FIG. 2 is a Scanning Electron Microscope (SEM) photograph of a seed DJ-1 obtained in comparative preparation example 1;

FIG. 3 is a Scanning Electron Microscope (SEM) photograph of a seed DJ-3 obtained in comparative preparation example 3;

FIG. 4 is an XRD diffraction pattern of a ZSM-5 molecular sieve material, wherein curve A is the XRD pattern of the seed crystal J-1 prepared in preparation example 1; curve B is the XRD spectrum of comparative seed DJ-1 prepared in comparative preparation example 1; curve C is the XRD spectrum of the ball milled seed crystal J-1 of example 1; curve D is the XRD spectrum of the comparative seed DJ-1 after ball milling in comparative example 4;

FIG. 5 is a Scanning Electron Microscope (SEM) picture of molecular sieve S-1 prepared in example 1;

FIG. 6 is a Scanning Electron Microscope (SEM) image of comparative molecular sieve DS-4 prepared in comparative example 4.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

According to the preparation method of the present invention, the first silicon source may be various silicon sources conventional in the art, for example, may be one or more of silica sol, sodium silicate, ethyl orthosilicate and white carbon black, and preferably silica sol.

According to the preparation method of the present invention, the first aluminum source may be a water-soluble aluminate and/or a water-soluble aluminum salt of an inorganic acid. Specifically, the first aluminum source may be one or more of sodium metaaluminate, aluminum nitrate and aluminum sulfate, preferably sodium metaaluminate.

According to the preparation method of the present invention, preferably, the first alkali source is an inorganic alkali, and may be sodium hydroxide and/or potassium hydroxide, preferably sodium hydroxide.

According to the preparation method of the invention, the first template agent can be a template agent commonly used in the field of synthesis of ZSM-5 molecular sieves, preferably a water-soluble quaternary ammonium salt, more preferably at least one of tetrapropylammonium bromide, tetrapropylammonium hydroxide and tetramethylammonium hydroxide, and further more preferably the first template agent is tetrapropylammonium bromide and/or tetrapropylammonium hydroxide.

According to the preparation method of the present invention, there is no particular requirement on the order of mixing the first silicon source, the first aluminum source, the first alkali source, the first template, the seed crystal, the urea and the water, and the above raw materials may be mixed uniformly before the aging stage, for example, the first template, the first alkali source, the first aluminum source and the water may be mixed first, and after stirring uniformly, the first silicon source, the seed crystal and the urea may be added sequentially. The stirring time is not particularly limited as long as the raw materials can be uniformly mixed.

According to a preferred embodiment of the present invention, the preparation method further comprises: and performing ball milling on the seed crystal, and then mixing the seed crystal with a first silicon source, a first aluminum source, a first alkali source, a first template, urea and water. By adopting the preferred embodiment of the invention, the spherical ZSM-5 molecular sieve containing the second template agent is subjected to ball milling and then is mixed with other raw materials, so that the nucleation induction period is favorably shortened, and the yield of the nanosheet ZSM-5 molecular sieve can be improved.

The ball milling conditions are selected from a wide range, and preferably, the ball milling conditions comprise: the rotating speed is 200-800r/min, and the time is 1-8h, and more preferably, the rotating speed is 300-600r/min, and the time is 2-6 h.

In the preparation method provided by the invention, the used seed crystal is the spherical ZSM-5 molecular sieve formed by accumulating the nanocrystals, and compared with the flaky ZSM-5 molecular sieve serving as the seed crystal, the ZSM-5 molecular sieve synthesized by taking the spherical ZSM-5 molecular sieve formed by accumulating the nanocrystals as the seed crystal has higher product selectivity and longer service life when being used for preparing propylene and butylene through methanol conversion.

The sphere of the invention means that the size ratio in the three-dimensional direction of the space is close to or equal to 1: 1:1, in the shape of a cylinder.

According to a preferred embodiment of the present invention, the spherical ZSM-5 molecular sieve containing the second templating agent is present in an amount of from 8 to 14 wt%, more preferably from 9 to 12.5 wt%, and most preferably from 9.5 to 12.2 wt%. The content of the second template agent can be measured by thermogravimetric analysis.

According to a preferred embodiment of the present invention, the spherical ZSM-5 molecular sieve containing the second templating agent has an average particle size of 0.8 to 1.7. mu.m, preferably 0.9 to 1.2. mu.m.

The average particle size of the spherical ZSM-5 molecular sieve containing the second template is measured by the Malvern laser particle sizer method.

According to a preferred embodiment of the present invention, the spherical ZSM-5 molecular sieve containing the second template is formed by stacking nanoparticles having an average particle size of 60 to 150nm, preferably 80 to 110 nm.

In the invention, the average particle size of the nano particles is calculated by an XRD method according to a Scherrer formula.

According to a preferred embodiment of the present invention, the method for preparing the seed crystal includes: and mixing a second silicon source, a second aluminum source, a second alkali source, a second template agent and water, sequentially performing second ageing and crystallization, and performing second drying (without roasting) on a solid product obtained by crystallization.

The selection range of the second silicon source is the same as that of the first silicon source, and is not described herein again.

The selection range of the second aluminum source is the same as that of the first aluminum source, and is not described herein again.

The selection range of the second alkali source is the same as that of the first alkali source, and is not described herein again.

The selection range of the second template is the same as that of the first template, and is not described herein again.

In the above method for producing the seed crystal, the inhibitor (urea) is not added, and the second template is not calcined after the second drying so that the second template is present in the seed crystal.

According to the present invention, preferably, the molar ratio of the second silicon source, the second aluminum source, the second alkali source, the second template agent and the water is 100: (0.2-2): (1-10): (5-25): (1000-2000), more preferably 100: (0.5-1): (3-5): (10-15): (1200) 1800), wherein the second silicon source is SiO₂The second aluminum source is calculated as Al₂O₃The second alkali source is calculated by oxide.

According to the preparation method of the invention, the time for the second aging is selected in a wide range, and for example, the time can be 1-36h, and preferably 16-24 h. The temperature of the second aging is not particularly limited, and may be, for example, room temperature (10 to 40 ℃). According to the present invention, preferably, the crystallization conditions include: the temperature is 100-135 ℃, and the time is 24-96 h; further preferably, the temperature is 110-125 ℃ and the time is 55-72 h.

The mixture obtained by crystallization can be subjected to solid-liquid separation by a conventional separation method to separate out solids in the mixture. According to the method of the invention, solid-liquid separation can be realized by adopting filtration.

After crystallization, the solid product obtained by solid-liquid separation may be dried under conventional conditions to obtain the seed crystal. Specifically, the drying can be carried out at a temperature of 80-120 ℃, and the drying time can be selected according to the drying temperature, and can be generally 8-12 h.

It should be noted that the terms "first" and "second" in the present invention do not have any phase-limiting effect on the respective components. The preparation of the crystal seed and the preparation of the ZSM-5 molecular sieve both relate to a silicon source, an aluminum source, an alkali source, a template agent and the like. The terms "first" and "second" are used merely to distinguish between materials or processes in the preparation of the ZSM-5 molecular sieve and in the preparation of the seed crystal. The crystallization refers to crystallization in the process of preparing the seed crystal, and the low-temperature crystallization and the high-temperature crystallization refer to crystallization in the process of preparing the ZSM-5 molecular sieve.

According to a preferred embodiment of the present invention, the molar ratio of the first silicon source, the first aluminum source, the first alkali source, the first template agent, urea and water is 100: (0.2-2): (1-10): (1-10): (10-300): (1000-2000), more preferably 100: (0.4-1): (2-8): (2-8): (50-300): (1200-2000), more preferably 100: (0.4-1): (3.5-4.2): (5-8): (100-300): (1500-1900), wherein the first silicon source is SiO₂The first aluminum source is calculated by Al₂O₃The first alkali source is calculated by oxide, wherein, the seed crystal is calculated by SiO₂The mass ratio of the first silicon source is 0.01-0.1: 1, preferably 0.02 to 0.08: 1. in the preferred embodiment, the first template agent is used in a small amount, so that the production cost is saved.

According to the preparation method of the invention, the aging time can be the aging treatment time which is conventional in the field, for example, the aging treatment time can be 1-36h, and preferably 16-24 h. Here, the temperature for aging is not particularly limited, and it may be carried out at room temperature (10 to 40 ℃ C.), for example. According to the invention, the ageing is preferably dynamic, i.e. the ageing is carried out under stirring conditions, more preferably the rotation speed of the stirring is 50-100 r/min.

According to the preparation method, the variable temperature crystallization process of low temperature and high temperature is adopted, the temperature of the low temperature crystallization is 90-130 ℃, and the temperature of the high temperature crystallization is 150-180 ℃. The preferred embodiment is more beneficial to improving the catalytic performance (including product selectivity and service life) of the prepared molecular sieve.

According to a preferred embodiment of the present invention, the low temperature crystallization conditions include: the temperature is 90-130 ℃, and the time is 12-48h (preferably 18-30 h); the high-temperature crystallization conditions comprise: the temperature is 150 ℃ and 180 ℃, and the time is 12-48 h. The ZSM-5 molecular sieve prepared by the preferred embodiment has smaller size, higher product selectivity and longer service life.

According to the preparation method of the present invention, the low temperature crystallization and the high temperature crystallization can be performed in various conventional crystallization equipment, for example, in a high pressure reaction vessel.

According to the preparation method of the invention, the mixture obtained by high-temperature crystallization can be subjected to solid-liquid separation by adopting a conventional separation method so as to separate out solids in the mixture. According to the method of the invention, solid-liquid separation can be realized by adopting filtration.

After high-temperature crystallization, the solid product obtained by solid-liquid separation can be dried and roasted under the conventional conditions, so as to obtain the seed crystal. Specifically, the drying can be carried out at a temperature of 80-120 ℃, and the drying time can be selected according to the drying temperature, and can be generally 8-12 h.

In the invention, the roasting is mainly used for removing substances, such as a template, remained in the pore channels of the molecular sieve in the synthesis process of the ZSM-5 molecular sieve. The calcination may be carried out at a temperature of 450-600 ℃, and the duration of the calcination may be selected according to the calcination temperature, and may be generally 2-10 h. The calcination is generally carried out in an air atmosphere.

In order to further improve the catalytic performance of the ZSM-5 molecular sieve prepared, preferably, the roasting conditions include: roasting at the temperature of 250-330 ℃ for 2-6h, and then roasting at the temperature of 500-600 ℃ for 4-10 h; further preferably, the calcination is carried out at 250-330 ℃ for 2-6h, and then at 500-550 ℃ for 4-10 h.

According to a second aspect of the present invention, there is provided a ZSM-5 molecular sieve produced by the preparation method of the present invention. In a scanning electron microscope picture of the molecular sieve, the length of the a-axis direction is 260-320nm, the length of the b-axis direction is 80-120nm, and the length of the c-axis direction is 580-630 nm. The ZSM-5 molecular sieve provided by the invention has a flaky nano-grade structure and smaller size.

According to the invention, in the three-dimensional direction, the c-axis direction refers to the longest length direction of the ZSM-5 molecular sieve; the b-axis direction of the invention refers to the thinnest direction of the ZSM-5 molecular sieve.

According to a third aspect of the present invention, there is provided a hydrogen-type ZSM-5 molecular sieve, the hydrogen-type ZSM-5 molecular sieve being formed by ion-exchanging the ZSM-5 molecular sieve prepared by the preparation method of the present invention.

The ZSM-5 molecular sieve material prepared by the method is non-hydrogen type and can be converted into hydrogen type by ion exchange. The method of ion exchange in the present invention is not particularly limited, and the ion exchange can be carried out by a conventional method. For example, the ZSM-5 molecular sieve prepared by the preparation method of the invention can be subjected to ammonium exchange to be converted into an ammonium type ZSM-5 molecular sieve material, and then the ammonium type ZSM-5 molecular sieve material is roasted to obtain the hydrogen type ZSM-5 molecular sieve.

According to a fourth aspect of the invention, the invention provides an application of the hydrogen type ZSM-5 molecular sieve provided by the invention in the preparation of propylene and butylene through a methanol conversion reaction.

According to the application of the present invention, the ZSM-5 molecular sieve is subjected to ion exchange to form the hydrogen type ZSM-5 molecular sieve, and then the step of forming the hydrogen type ZSM-5 molecular sieve is included, for example, the hydrogen type ZSM-5 molecular sieve is subjected to tabletting and sieving to obtain the formed hydrogen type high silicon ZSM-5 molecular sieve, and the tabletting and sieving can be a method which is conventional in the field.

The method for preparing propylene and butylene by methanol conversion of the present invention is not particularly limited in the conditions for contacting methanol with the hydrogen type ZSM-5 molecular sieve, and may be carried out under the conventional reaction conditions for preparing propylene and butylene by methanol conversion.

In the following and comparative examples, the amount of template in the seed crystals was determined by thermogravimetric analysis, commercially available from NETZSCH under the designation STA 449F 3. The percentage weight loss of the seed between 300-500 ℃ was determined by thermogravimetric analysis, corresponding to the amount of template in the seed, wherein the test was carried out in an air atmosphere at a temperature rise rate of 10 ℃/min.

In the following preparations and comparative preparations, the morphology of the prepared molecular sieve was observed on a Scanning Electron Microscope (SEM) of Nova Nano SEM 450, model, available from FEI.

The average particle size of the seed crystals was measured using a malvern laser particle sizer Mastersizer 3000.

The phase results of the samples were characterized by a Bruker X-ray diffractometer model D8ADVANCE and the average particle size of the nanoparticles was calculated according to the Scherrer formula.

The following preparations and comparative preparations are used to illustrate the preparation of seed crystals.

Preparation example 1

Mixing 25.87g of TPAOH aqueous solution with the mass percent of 25% with 13g of deionized water, sequentially adding 0.71g of NaOH and 0.242g of sodium metaaluminate, and stirring at the speed of 200r/min for 1 hour to form transparent solution. 63g of silica sol having a mass content of 30% were added thereto, and the mixture was stirred at a speed of 200r/min for 1 hour. The mol ratio of the silica sol, sodium metaaluminate, NaOH, TPAOH and water is 100: 0.5: 2.8: 10.1: 1351.1 silica sol by SiO₂Calculated as Al, sodium metaaluminate₂O₃Calculated as Na, NaOH₂And (4) measuring O. Aging the obtained mixture at room temperature (25 deg.C) for 24h, transferring the aged reaction solution into a high-pressure reaction kettle, crystallizing at 125 deg.C for 72h, taking out, washing for 5 times, and filtering; finally, the mixture was dried at 110 ℃ for 5 hours to obtain seed crystal J-1.

XRD analysis of seed J-1 (as shown in FIG. 4, where curve A is seed J-1 from preparation 1) indicated that the material was ZSM-5 molecular sieve material. The appearance of the seed crystal J-1 is observed by using SEM, as shown in figure 1, and figures 1a and 1b are SEM images of the seed crystal J-1 under different magnifications to confirm that the seed crystal J-1 is a micron-sized spherical aggregate formed by stacking nano particles. The results of the average particle size of the nanoparticles, the average particle size of the micro-sized spherical aggregates, and the content of the template in the seed J-1 are shown in Table 1.

Preparation example 2

Mixing 25.87g of TPAOH aqueous solution with the mass percent of 25% with 13g of deionized water, sequentially adding 0.71g of NaOH and 0.242g of sodium metaaluminate, and stirring at the speed of 200r/min for 1 hour to form transparent solution. 63g of silica sol having a mass content of 30% were added thereto, and the mixture was stirred at a speed of 200r/min for 1 hour. The mol ratio of the silica sol, sodium metaaluminate, NaOH, TPAOH and water is 100: 0.5: 3: 10.8: 1440, silica sol SiO₂Calculated as Al, sodium metaaluminate₂O₃Calculated as Na, NaOH₂And (4) measuring O. Aging the obtained mixture at room temperature (25 deg.C) for 24h, transferring the aged reaction solution into a high-pressure reaction kettle, crystallizing at 115 deg.C for 60h, taking out, washing for 5 times, and filtering; finally drying at 110 ℃ for 5h to obtain the seed crystal J-2.

XRD analysis is carried out on the seed crystal J-2, and the material is a ZSM-5 molecular sieve material. And observing the appearance of the seed crystal J-2 by using an SEM (scanning electron microscope), and determining that the seed crystal J-2 is a micron-sized spherical aggregate formed by stacking nano particles. The results of the average particle size of the nanoparticles, the average particle size of the micro-sized spherical aggregates, and the content of the template in the seed J-2 are shown in Table 1.

Preparation example 3

Mixing 25.87g of TPAOH aqueous solution with the mass percent of 25% with 13g of deionized water, sequentially adding 0.71g of NaOH and 0.242g of sodium metaaluminate, and stirring at the speed of 200r/min for 1 hour to form transparent solution. 63g of silica sol having a mass content of 30% were added thereto, and the mixture was stirred at a speed of 200r/min for 1 hour. The mol ratio of the silica sol, sodium metaaluminate, NaOH, TPAOH and water is 100: 0.5: 3: 10.8: 1440, silica sol SiO₂Calculated as Al, sodium metaaluminate₂O₃Calculated as Na, NaOH₂And (4) measuring O. Aging the obtained mixture at room temperature (25 deg.C) for 24h, transferring the aged reaction solution into a high-pressure reaction kettle, crystallizing at 110 deg.C for 55h, taking out, washing for 5 times, and filtering; finally, the mixture was dried at 110 ℃ for 5 hours to obtain seed J-3.

XRD analysis is carried out on the seed crystal J-3, and the material is a ZSM-5 molecular sieve material. And observing the appearance of the seed crystal J-3 by using an SEM (scanning electron microscope), and determining that the seed crystal J-2 is a micron-sized spherical aggregate formed by stacking nano particles. The results of the average particle size of the nanoparticles, the average particle size of the micro-sized spherical aggregates, and the content of the template in the seed J-3 are shown in Table 1.

TABLE 1

Comparative preparation example 1

According toThe process of preparation example 1, except that during the preparation of the seed crystal, urea, SiO was added₂The molar ratio of silica sol to urea is 100: 100, and the crystallization temperature is higher than that of preparation example 1, and the specific crystallization conditions are as follows: crystallizing at 150 deg.C for 50h to obtain comparative seed DJ-1.

XRD analysis of comparative seed DJ-1 (as shown in FIG. 4, where curve B is comparative seed DJ-1 prepared in comparative preparation example 1) indicated that the material was ZSM-5 molecular sieve material. The morphology of the comparative seed DJ-1 was observed by SEM, and as shown in FIG. 2, the comparative seed DJ-1 was confirmed to be flaky.

Comparative preparation example 2

According to the method of preparation example 1, except that the seed preparation further comprises roasting the seed J-1 at 550 ℃ for 6h to obtain comparative seed DJ-2, and determining that the comparative seed DJ-2 does not contain the template through thermogravimetric analysis.

Comparative preparation example 3

Comparative seed DJ-3 having a spheroid-like shape was obtained by following the procedure of preparation example 1 except that the temperature of crystallization was 145 ℃.

XRD analysis of the comparative crystal seed DJ-3 shows that the material is ZSM-5 molecular sieve material. The morphology of the comparative seed DJ-3 was observed by SEM, and as shown in FIG. 3, the comparative seed DJ-3 was determined to be rod-shaped.

Example 1

(1) 12.21g of TPAOH aqueous solution with the mass percentage of 25 percent is mixed with 50g of deionized water, 0.842g of NaOH and 0.242g of sodium metaaluminate are sequentially added, and the mixture is stirred for 1 hour at the speed of 200r/min to form transparent solution. 58.62g of silica sol with a mass content of 30% was added, the mixture was stirred at a speed of 200r/min for 1 hour, and then 0.879g of seed crystal J-1 (as shown in FIG. 4, wherein curve C is the seed crystal J-1 after ball milling in example 1) and 17.58g of urea were added, the molar ratio of silica sol, sodium metaaluminate, NaOH, TPAOH, urea and water was 100: 0.5: 3.6: 5: 100: 1898 wherein the silica sol is SiO₂Calculating sodium metaaluminate by Al₂O₃Calculated as Na, NaOH₂And (4) measuring O. The resulting mixture was dynamically aged (stirring speed 100r/min) at room temperature (25 ℃) for 24h to obtain a gel.

(2) And transferring the gel to a high-pressure reaction kettle, crystallizing for 24 hours at 100 ℃, and then heating to 170 ℃ for crystallizing for 24 hours. And filtering the mixture obtained by crystallization, washing the obtained solid product with deionized water at room temperature (25 ℃), drying at 120 ℃ for 8h, and then roasting at 300 ℃ for 4h and 550 ℃ for 8h to obtain the molecular sieve S-1.

XRD analysis is carried out on the obtained molecular sieve S-1, and the molecular sieve material is confirmed to be ZSM-5 molecular sieve. As shown in FIG. 5, the morphology of the molecular sieve S-1 was observed by SEM, and the length of the molecular sieve S-1 in the a-axis direction was about 280-320nm, the length of the molecular sieve S-1 in the b-axis direction was about 80-120nm, and the length of the molecular sieve S-1 in the c-axis direction was about 580-630 nm.

Example 2

(1) 12.21g of TPAOH aqueous solution with the mass percentage of 25 percent is mixed with 50g of deionized water, 0.842g of NaOH and 0.242g of sodium metaaluminate are sequentially added, and the mixture is stirred for 1 hour at the speed of 200r/min to form transparent solution. Adding 58.62g of silica sol with the mass content of 30%, stirring at the speed of 200r/min for 1h, then adding 0.879g of seed crystal J-2 ball-milled for 4h at 300r/min and 17.58g of urea, wherein the molar ratio of the silica sol, sodium metaaluminate, NaOH, TPAOH, urea and water is 100: 0.5: 3.6: 5: 100: 1898 wherein the silica sol is SiO₂Calculating sodium metaaluminate by Al₂O₃Calculated as Na, NaOH₂And (4) measuring O. The resulting mixture was dynamically aged (stirring speed 100r/min) at room temperature (25 ℃) for 20h to obtain a gel.

(2) And transferring the gel to a high-pressure reaction kettle, crystallizing for 30 hours at 90 ℃, and then heating to 150 ℃ for crystallizing for 48 hours. And filtering the mixture obtained by crystallization, washing the obtained solid product with deionized water at room temperature (25 ℃), drying at 120 ℃ for 8h, and then roasting at 250 ℃ for 6h and 500 ℃ for 10h to obtain the molecular sieve S-2.

XRD analysis is carried out on the obtained molecular sieve S-2, and the molecular sieve material is confirmed to be a ZSM-5 molecular sieve. The morphology of the molecular sieve S-2 is similar to that of the molecular sieve S-1.

Example 3

(1) 9.65g of the powder with the mass percentage of 25 percentTPAOH aqueous solution and 20g deionized water mixed, sequentially added with 0.485g NaOH and 0.242g sodium metaaluminate, stirred at 200r/min for 1h, formed transparent solution. Adding 29.31g of silica sol with the mass content of 30%, stirring at the speed of 200r/min for 1h, then adding 0.439g of seed crystal J-3 and 26.37g of urea, wherein the seed crystal J-3 is ball-milled at the rotating speed of 600r/min for 2h, and the molar ratio of the silica sol, sodium metaaluminate, NaOH, TPAOH, urea and water is 100: 1: 4: 8: 300: 1813 dissolving silica sol with SiO₂Calculating sodium metaaluminate by Al₂O₃Calculated as Na, NaOH₂And (4) measuring O. The resulting mixture was dynamically aged (stirring speed 100r/min) at room temperature (25 ℃) for 16h to give a gel.

(2) And transferring the gel to a high-pressure reaction kettle, crystallizing for 18 hours at 130 ℃, and then heating to 180 ℃ for crystallization for 12 hours. And filtering the mixture obtained by crystallization, washing the obtained solid product with deionized water at room temperature (25 ℃), drying at 120 ℃ for 8h, and then roasting at 330 ℃ for 2h and 600 ℃ for 4h to obtain the molecular sieve S-3.

XRD analysis is carried out on the obtained molecular sieve S-3, and the molecular sieve material is confirmed to be a ZSM-5 molecular sieve. The morphology of the molecular sieve S-3 is similar to that of the molecular sieve S-1.

Example 4

The procedure of example 1 was followed except that the seed crystal J-1 was not ball-milled but directly mixed with other raw materials in accordance with the step (1) of example 1. Obtaining the molecular sieve S-4 of the invention.

XRD analysis is carried out on the obtained molecular sieve S-4, and the molecular sieve material is confirmed to be ZSM-5 molecular sieve.

Example 5

The process of example 1 was followed except that the calcination in step (2) was carried out at 550 ℃ for 10 hours. Obtaining the molecular sieve S-5 of the invention.

XRD analysis is carried out on the obtained molecular sieve S-5, and the molecular sieve material is confirmed to be a ZSM-5 molecular sieve.

Comparative example 1

The process of example 1 was followed except that the temperature of the high temperature crystallization was 200 ℃. Comparative molecular sieve DS-1 was obtained.

Comparative example 2

The process of example 1 was followed except that the temperature of the low-temperature crystallization was 80 ℃. Comparative molecular sieve DS-2 was obtained.

Comparative example 3

The process of example 1 was followed, except that the crystallization in the autoclave did not include low temperature crystallization, and the crystallization was carried out directly at a high temperature of 170 ℃ for 48 hours. Comparative molecular sieve DS-3 was obtained.

Comparative example 4

The procedure of example 1 was followed except that the seed crystal J-1 was replaced with the comparative seed crystal DJ-1 obtained in comparative preparation example 1 of an equal mass (as shown in FIG. 4, wherein curve D is the comparative seed crystal DJ-1 after ball milling in comparative example 4). Comparative molecular sieve DS-4 was obtained.

The morphology of the comparative molecular sieve DS-4 was observed by SEM, as shown in FIG. 6. As can be seen from a comparison of fig. 5 and 6, the molecular sieve produced by the method of example 1 of the present invention is smaller in size.

Comparative example 5

The procedure is as in example 1, except that the seed crystals J-1 are replaced by equivalent masses of comparative seed crystals DJ-2 from comparative preparation 2. Comparative molecular sieve DS-5 was obtained.

Comparative example 6

The procedure is as in example 1, except that the seed crystal J-1 is replaced by an equivalent mass of the comparative seed crystal DJ-3 obtained in comparative preparation 3. Comparative molecular sieve DS-6 was obtained.

The above examples demonstrate that the ZSM-5 molecular sieve material can be prepared by the method for preparing the ZSM-5 molecular sieve of the invention, and the prepared ZSM-5 molecular sieve has smaller size.

Test example 1

(1) The molecular sieve samples synthesized in the above examples and comparative examples were respectively treated with 0.5mol/L NH₄NO₃Solution (ZSM-5 molecular sieve and NH)₄NO₃NH in solution₄NO₃In a weight ratio of 1:10) at 80 ℃ for 3 times of ion exchange, converting into an ammonium type ZSM-5 molecular sieve, and then roasting at 400 ℃ for 10 hours to obtain the hydrogen type ZSM-5 molecular sieve.

(2) Hydrogen prepared in the step (1)And tabletting and screening the type ZSM-5 molecular sieve, and selecting particles of 20-40 meshes for reaction evaluation of preparing propylene and butylene by methanol conversion. The evaluation is carried out in a fixed bed reactor, raw material methanol enters a preheating furnace under the carrying of nitrogen as carrier gas after passing through a flow metering pump, is vaporized into gas in the preheating furnace, and then enters the fixed bed reactor for reaction. Wherein the loading of the catalyst is 1g, and the volume ratio of methanol to nitrogen is 4: 1, the weight space velocity of the methanol is 3h^-1The reaction temperature was 480 ℃ and the pressure was 0.1MPa (in terms of gauge pressure).

And when the reaction is carried out for 165h, analyzing the reaction product output from the fixed bed reactor by using an online gas chromatograph, and calculating the selectivity of ethylene, the selectivity of propylene, the selectivity of butylene, the total selectivity of propylene and butylene and the service life of the molecular sieve. The service life is defined as the reaction time at which the methanol conversion can reach 99% or more, and the results are shown in table 2.

TABLE 2

It can be seen from the results in table 2 that the hydrogen type ZSM-5 molecular sieve of the present invention can maintain high activity for a long time and has high selectivity to propylene and butene when used as a catalyst for methanol conversion reaction.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for preparing a ZSM-5 molecular sieve, the method comprising:

the low-temperature crystallization temperature is 90-130 ℃, the high-temperature crystallization temperature is 150-180 ℃, the seed crystal is a spherical ZSM-5 molecular sieve containing a second template agent, and the seed crystal is obtained by crystallization at the temperature of 100-135 ℃;

the spherical ZSM-5 molecular sieve containing the second template has the average particle size of 0.8-1.7 mu m, and is formed by stacking nanoparticles with the average particle size of 60-150 nm.

2. The production method according to claim 1, wherein the production method further comprises: and performing ball milling on the seed crystal, and then mixing the seed crystal with a first silicon source, a first aluminum source, a first alkali source, a first template, urea and water.

3. The method of claim 2, wherein the ball milling conditions comprise: the rotating speed is 200-800r/min, and the time is 1-8 h.

4. The preparation method of claim 3, wherein the ball milling conditions comprise: the rotating speed is 300-600r/min, and the time is 2-6 h.

5. The production method according to any one of claims 1 to 4, wherein the molar ratio of the first silicon source, the first aluminum source, the first alkali source, the first template, urea and water is 100: (0.2-2): (1-10): (1-10): (10-300): (1000-2000), wherein the first silicon source is SiO₂The first aluminum source is calculated by Al₂O₃The first alkali source is calculated by oxide, the seed crystal and SiO₂The mass ratio of the first silicon source is 0.01-0.1: 1.

6. according to the claimsThe preparation method according to claim 5, wherein the molar ratio of the first silicon source, the first aluminum source, the first alkali source, the first template agent, urea and water is 100: (0.4-1): (2-8): (2-8): (50-300): (1200-2000), wherein the first silicon source is SiO₂The first aluminum source is calculated by Al₂O₃The first alkali source is calculated by oxide, the seed crystal and SiO₂The mass ratio of the first silicon source is 0.02-0.08: 1.

7. the method according to any one of claims 1 to 4, wherein the aging time is 1 to 36 hours.

8. The production method according to any one of claims 1 to 4, wherein the conditions for the low-temperature crystallization include: the temperature is 90-130 ℃, and the time is 12-48 h; the high-temperature crystallization conditions comprise: the temperature is 150 ℃ and 180 ℃, and the time is 12-48 h.

9. The production method according to any one of claims 1 to 4, wherein the conditions for the calcination include: roasting at 250-330 deg.c for 2-6 hr and then at 500-600 deg.c for 4-10 hr.

10. The method according to any one of claims 1 to 4, wherein the spherical ZSM-5 molecular sieve containing the second template has a content of the second template of 8 to 14 wt%.

11. The method of claim 10, wherein the spherical ZSM-5 molecular sieve containing the second template has a content of the second template of 9 to 12.5 wt%.

12. The method of claim 1, wherein the spherical ZSM-5 molecular sieve containing the second template has an average particle size of 0.9 to 1.2 μm.

13. The method of claim 1, wherein the nanoparticles have an average particle size of 80-110 nm.

14. The production method according to any one of claims 1 to 4, wherein the seed crystal is produced by a method comprising:

and mixing a second silicon source, a second aluminum source, a second alkali source, a second template agent and water, sequentially performing second ageing and crystallization, and performing second drying on a solid product obtained by crystallization.

15. The preparation method according to claim 14, wherein the molar ratio of the second silicon source, the second aluminum source, the second alkali source, the second template agent and the water is 100: (0.2-2): (1-10): (5-25): (1000-2000), wherein the second silicon source is SiO₂The second aluminum source is calculated as Al₂O₃The second alkali source is calculated by oxide.

16. The production method according to claim 14, wherein the conditions of the second aging include: the time is 1-36 h.

17. The preparation method of claim 14, wherein the crystallization conditions include: the temperature is 100 ℃ and 135 ℃, and the time is 24-96 h.

18. The preparation method of claim 17, wherein the crystallization conditions include: the temperature is 110-125 ℃, and the time is 55-72 h.

19. A ZSM-5 molecular sieve produced by the method of any of claims 1-18.

20. A hydrogen form ZSM-5 molecular sieve formed by ion exchange of the ZSM-5 molecular sieve recited in claim 19.

21. Use of the hydrogen ZSM-5 molecular sieve of claim 20 in the conversion of methanol to propylene and butene.

22. A process for the conversion of methanol to propylene and butene comprising contacting methanol with the hydrogen ZSM-5 molecular sieve as claimed in claim 20 under reaction conditions for the conversion of methanol to propylene and butene.