Synthetic method of SAPO-34 molecular sieve, synthetic molecular sieve and application thereof
阅读说明：本技术 Sapo-34分子筛的合成方法、合成的分子筛及其用途 (Synthetic method of SAPO-34 molecular sieve, synthetic molecular sieve and application thereof ) 是由 管洪波 刘红星 丁佳佳 陆贤 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种SAPO-34分子筛的合成方法、合成的分子筛及其在含氧化合物制烯烃的反应中的应用。该方法包括：对包含硅源、磷源、铝源、模板剂和水形成的混合物I,进行水热晶化,得到包含晶种的导向剂A；将磷源、铝源、硅源和水制成混合物Ⅱ,制成硅磷铝干胶B；将硅磷铝干胶B与导向剂A混合,得到混合物Ⅲ；混合物Ⅲ在140～170℃下水热处理0.1～12小时,然后在180～220℃下水热晶化2～48h,制得SAPO-34分子筛。采用本发明合成方法,分子筛收率高,所合成的SAPO-34分子筛结晶度高,产品质量好,用于含氧化合物制烯烃反应中,具有低碳烯烃收率高的优点。(The invention discloses a synthetic method of an SAPO-34 molecular sieve, the synthesized molecular sieve and application thereof in reaction for preparing olefin from oxygen-containing compounds. The method comprises the following steps: performing hydrothermal crystallization on a mixture I formed by a silicon source, a phosphorus source, an aluminum source, a template agent and water to obtain a directing agent A containing seed crystals; preparing a mixture II from a phosphorus source, an aluminum source, a silicon source and water to prepare a silicon-phosphorus-aluminum dry adhesive B; mixing the silicon-phosphorus-aluminum dry glue B with a guiding agent A to obtain a mixture III; and carrying out hydrothermal treatment on the mixture III at the temperature of 140-170 ℃ for 0.1-12 hours, and carrying out hydrothermal crystallization at the temperature of 180-220 ℃ for 2-48 hours to obtain the SAPO-34 molecular sieve. The synthesis method has the advantages of high molecular sieve yield, high crystallinity of the synthesized SAPO-34 molecular sieve, good product quality, and high yield of low-carbon olefin when being used in the reaction of preparing olefin from oxygen-containing compounds.)
1. A synthetic method of SAPO-34 molecular sieve comprises the following steps:
a) performing hydrothermal crystallization on a mixture I formed by a silicon source, a phosphorus source, an aluminum source, a template agent and water to obtain a directing agent A containing seed crystals;
b) preparing a mixture II from a phosphorus source, an aluminum source, a silicon source and water to prepare a silicon-phosphorus-aluminum dry adhesive B;
c) mixing the silicon-phosphorus-aluminum dry glue B obtained in the step B) with the guiding agent A obtained in the step a) to obtain a mixture III;
d) carrying out hydrothermal treatment on the mixture III obtained in the step c) at 140-170 ℃ for 0.1-12 hours, and carrying out hydrothermal crystallization at 180-220 ℃ for 2-48 hours to obtain the SAPO-34 molecular sieve.
2. The synthesis process according to claim 1, wherein in step a), the molar composition of the raw materials in mixture I is: mR (Si)aAlbPc)O2Wherein R is a template, m is the mole number of the template, m is 0.03-1.0, a is 0.01-0.30, b is 0.30-0.60, c is 0.30-0.60, and the condition that a + b + c is 1 is satisfied, and the aluminum source is calculated by Al: water 1: 5 to 60.
3. The synthesis method according to claim 1, wherein in the step b), the molar ratio of each substance is as follows: (Si)aAlbPc)O2A is 0.01 to 0.30, b is 0.30 to 0.60, c is 0.30 to 0.60, and the condition that a + b + c is 1 is satisfied, and an aluminum source is calculated as Al: water 1: 5 to 30.
4. The synthesis method according to claim 1, wherein in step c), the ratio of the directing agent A to the silicon-phosphorus-aluminum dry glue B is Al2O3And (2) the molar ratio is 1: (0.1-3.0).
5. The synthesis method according to claim 1, wherein the template is at least one selected from tetraalkylammonium compound, cyclohexylamine, morpholine, di-n-propylamine, tripropylamine, triethylamine, diethylamine, triethanolamine, and piperidine, and preferably the template is at least one selected from tetraethylammonium hydroxide, tetrapropylammonium bromide, triethylamine, diethylamine, and morpholine.
6. The synthesis method according to claim 1, wherein the hydrothermal crystallization conditions in step a) are as follows: performing hydrothermal crystallization at 180-220 ℃ for 0.1-12 h; the crystallization temperature is preferably 190-210 ℃, and the crystallization time is 2-6 hours.
7. The synthesis method according to claim 1, wherein the conditions of the hydrothermal treatment of step d) comprise: carrying out hydrothermal treatment at 150-170 ℃ for 0.5-4 hours.
8. The synthesis method according to claim 1 or 7, wherein the hydrothermal crystallization conditions of step d) comprise: the crystallization temperature is 180-200 ℃, and the crystallization time is 12-24 hours.
9. A SAPO-34 molecular sieve, characterized by: prepared by the synthesis method of any one of claims 1 to 8.
10. Use of the molecular sieve of claim 9 in an oxygenate to olefin reaction.
Technical Field
The invention relates to a synthetic method of an SAPO-34 molecular sieve, the synthetic molecular sieve and application thereof.
Background
Ethylene and propylene are important basic raw materials for modern petrochemical industry. The traditional preparation method of ethylene and propylene relies on petroleum raw materials, combines the actual distribution situation of fossil energy of rich coal, poor gas and little oil in China, improves and transforms the production level of the coal chemical industry in China, and develops a novel coal chemical industry technology to accord with the national security and energy strategy in China. The methanol-to-olefin route has attracted extensive attention because its raw material can be obtained from synthesis gas in large quantities, cheaply and conveniently, and therefore it has significant meaning to obtain ethylene and propylene in high yield from methanol conversion.
The core of the technology for preparing olefin from methanol is the development of a molecular sieve catalyst, and the catalyst used in the early stage of preparing olefin from methanol is mostly a silicon-aluminum zeolite molecular sieve such as ZSM-5, but the pore diameter is relatively large, the acidity is too strong, and the yield of low-carbon olefin is not high. In 1982, united states carbon compound company (UCC) synthesized SAPO series silicoaluminophosphate molecular sieves for the first time, among which SAPO-34 molecular sieves, which have a chabazite-like structure, a small pore diameter, moderate acidity and strong hydrothermal stability, and showed excellent low carbon olefin selectivity in the reaction of catalyzing methanol to prepare low carbon olefins, were attracting wide attention of researchers in China and foreign countries.
The synthesis method of the SAPO-34 molecular sieve comprises a hydrothermal synthesis method, a gas phase transfer synthesis method, a microwave synthesis method and the like, wherein the most common method is hydrothermal synthesis (USP4440871 and CN 1037334C, CN 1038125C, CN 1048428C), namely, a SAPO-34 molecular sieve product is obtained by crystallizing a crystallization liquid containing a silicon source, an aluminum source, a phosphorus source, a template and water in a high-temperature hydrothermal system. In the process of the SAPO-34 molecular sieve hydro-thermal synthesis, the mother liquor after the solid-liquid separation of the product and the wastewater for washing the molecular sieve contain a large amount of organic template agents, which brings harm to the environment, and the treatment cost of a large amount of wastewater also reduces the benefit of production enterprises. How to reduce the amount of waste water and the difficulty in recovering the organic template is a serious problem in the industrial process of the SAPO-34 molecular sieve.
The gas phase method has been intensively studied in the field of zeolite molecular sieves, particularly ZSM-5 molecular sieves, as a method for preparing molecular sieves, but few reports are made in the field of synthesis of aluminophosphate molecular sieves. The vapor phase method is characterized in that in the synthesis process, a molecular sieve synthesis precursor is prepared into dry glue under certain conditions, then the dry glue is placed on the upper part of a reaction kettle, a certain amount of mixed solution of organic amine and water is added to the bottom of the reaction kettle to serve as a template agent, and the dry glue is not contacted with a liquid phase part. Compared with the traditional hydrothermal synthesis, the gas phase method can greatly reduce the usage amount of the organic template agent, save the complex step of separating the product from the mother liquor, and easily recover and reuse the organic template agent, but on the other hand, the traditional gas phase method has the problems of low production efficiency and poor quality of molecular sieve products.
CN1363519A uses gas phase method to prepare SAPO-34 molecular sieve, which is characterized in that only the liquid phase part uses organic template agent, the crystallinity of the molecular sieve is poor. CN1693202A is a template agent put in the dry glue preparation process, but experiments prove that the SAPO-34 molecular sieve prepared by the method has unobvious improvement on the crystallinity, has poor activity when used for preparing olefin from methanol and has high coking rate. CN102372288A improves the problem of poor crystallinity of the obtained molecular sieve by adding fluoride to the preparation process of the dry glue.
In conclusion, the hydrothermal synthesis method has the problems of large consumption of organic template agent and generation of a large amount of wastewater, the traditional gas phase method has the problems of low production efficiency and poor quality of molecular sieve products, and although the gas phase method improves the product quality to a certain extent, the obtained molecular sieve still has the problems of low product crystallinity and poor product quality.
Disclosure of Invention
Aiming at the problems of low molecular sieve yield and poor product quality in the gas phase method in the prior art, the invention provides a synthetic method of an SAPO-34 molecular sieve, the synthesized molecular sieve and application thereof. The synthesis method has the advantages of high molecular sieve yield, high crystallinity of the synthesized SAPO-34 molecular sieve, good product quality, and high yield of low-carbon olefin when being used in the reaction of preparing olefin from oxygen-containing compounds.
The invention provides a synthesis method of an SAPO-34 molecular sieve, which comprises the following steps:
a) performing hydrothermal crystallization on a mixture I formed by a silicon source, a phosphorus source, an aluminum source, a template agent and water to obtain a directing agent A containing seed crystals;
b) preparing a mixture II from a phosphorus source, an aluminum source, a silicon source and water to prepare a silicon-phosphorus-aluminum dry adhesive B;
c) mixing the silicon-phosphorus-aluminum dry glue B obtained in the step B) with the guiding agent A obtained in the step a) to obtain a mixture III;
d) carrying out hydrothermal treatment on the mixture III obtained in the step c) at 140-170 ℃ for 0.1-12 hours, and carrying out hydrothermal crystallization at 180-220 ℃ for 2-48 hours to obtain the SAPO-34 molecular sieve.
According to one aspect of the invention, in step a), the molar composition of the raw materials in mixture I is: mR (Si)aAlbPc)O2Wherein R is a template, m is the mole number of the template, m is 0.03-1.0, a is 0.01-0.30, b is 0.30-0.60, c is 0.30-0.60, and the condition that a + b + c is 1 is satisfied, wherein the silicon source is calculated by Si, the aluminum source is calculated by Al, and the phosphorus source is calculated by P; the aluminum source is calculated as Al: water 1: 5 to 60.
According to one aspect of the invention, in step b), the molar ratio composition of each substance is: (Si)aAlbPc)O20.01-0.30% of a, 0.30-0.60% of b, 0.30-0.60% of c, and the condition that a + b + c is 1 is satisfied, wherein the silicon source is calculated by Si, the aluminum source is calculated by Al, and the phosphorus source is calculated by P; the aluminum source is calculated as Al: water 1: 5 to 30.
According to one aspect of the invention, in step c), the ratio of directing agent A and silicon-phosphorus-aluminum dry glue B is such that Al is contained therein2O3And (2) the molar ratio is 1: (0.1-3.0).
According to an aspect of the present invention, the conditions of the hydrothermal crystallization of step a) are as follows: performing hydrothermal crystallization at 180-220 ℃ for 0.1-12 h; the crystallization temperature is preferably 190-210 ℃, and the crystallization time is 2-6 hours.
According to one aspect of the invention, the conditions of the hydrothermal treatment of step d) comprise: carrying out hydrothermal treatment at 150-170 ℃ for 0.5-4 hours.
According to an aspect of the present invention, the hydrothermal crystallization conditions of step d) include: the crystallization temperature is 180-200 ℃, and the crystallization time is 12-24 hours.
The second aspect of the invention also provides the SAPO-34 molecular sieve, and the SAPO-34 molecular sieve is prepared according to the synthesis method of the SAPO-34 molecular sieve.
The third aspect of the invention also provides application of the SAPO-34 molecular sieve prepared by the SAPO-34 molecular sieve synthesis method in reaction for preparing olefin from oxygen-containing compounds.
In the process of synthesizing SAPO-34 by the traditional liquid phase method, water in the initial gel mixture plays a role of a solvent and also plays a role of adjusting the pH of the solution to meet the synthesis conditions, so that the using amount of the water cannot be reduced without limitation; after the solid-liquid separation of the product molecular sieve, a large amount of waste liquid containing the template agent needs to be treated, which not only causes economic waste, but also is a great challenge to environmental protection. In order to solve the problem, the traditional gas phase method for synthesizing SAPO-34 adopts a method of separating silicoaluminophosphate dry glue from a template solution to reduce the dosage of the template and water, but the traditional gas phase method has the problems of low production efficiency and low crystallinity of a molecular sieve, so that the traditional gas phase method is difficult to apply to industrial production.
In order to solve the problems, the invention specifically adopts the following steps: step a) firstly synthesizing a directing agent A containing a new large crystal, wherein the crystal has the characteristics of large grain size and many structural defects; step B) preparing silicon-phosphorus-aluminum dry glue B, wherein wastewater needing to be treated is not generated in the step; and c) adding the silicoaluminophosphate dry gel B into the guiding agent A, and carrying out hydrothermal treatment under the condition of being lower than the crystallization temperature, wherein at the moment, the newly-generated large crystals in the guiding agent A collapse into a large number of SAPO-34 molecular sieve fragments in structure and play a role in guiding seed crystals and structures for subsequent crystallization synthesis, and on the other hand, the template agent in the guiding agent fully acts with the silicoaluminophosphate dry gel B, and then the temperature is raised to the crystallization temperature required for synthesizing the SAPO-34 molecular sieve, so that the SAPO-34 molecular sieve product with high yield, good crystallinity and small particle size can be obtained. In the invention, the use of the silicon-phosphorus-aluminum dry glue effectively improves the utilization efficiency of the template agent and the solution water, reduces the pressure of the treatment of the synthetic waste liquid, and can obtain more molecular sieve products compared with the traditional liquid phase method; the preparation of the new large crystal in the guiding agent A and the hydrothermal pretreatment before crystallization synthesis play a good role in structure guiding for the hydrothermal crystallization synthesis of the molecular sieve, thereby obtaining the molecular sieve product with better crystallinity and grain size than the traditional gas phase method.
The SAPO-34 molecular sieve synthesized by the method is used in the reaction of preparing olefin from oxygen-containing compounds, and has the advantage of high yield of low-carbon olefin.
Drawings
FIG. 1 is an XRD pattern of the molecular sieves obtained in the examples and comparative examples;
FIG. 2 is an SEM photograph of a sample obtained in comparative example 1;
FIG. 3 is an SEM photograph of a sample obtained in comparative example 2;
FIG. 4 is an SEM photograph of a sample obtained in example 6.
Detailed Description
The following detailed description of the embodiments of the present invention is provided, but it should be noted that the scope of the present invention is not limited by the embodiments, but is defined by the appended claims.
All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, including definitions, will control.
When the specification concludes with claims with the heading "known to those skilled in the art", "prior art", or the like, to derive materials, substances, methods, procedures, devices, or components, etc., it is intended that the subject matter derived from the heading encompass those conventionally used in the art at the time the disclosure was made, but also include those that are not currently used, but would become known in the art to be suitable for a similar purpose.
In the context of the present specification, anything or things which are not mentioned, except where explicitly stated, are directly applicable to those known in the art without any changes. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or concepts resulting therefrom are considered part of the original disclosure or original disclosure of the invention, and should not be considered as new matters not disclosed or contemplated herein, unless a person skilled in the art would consider such a combination to be clearly unreasonable.
Unless otherwise expressly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise not in accordance with the conventional knowledge of those skilled in the art.
All pressures mentioned in this specification are gauge pressures unless explicitly stated.
The invention is further elucidated below.
The invention relates to a synthetic method of an SAPO-34 molecular sieve, which comprises the following steps:
a) subjecting a mixture I comprising a silicon source, a phosphorus source, an aluminum source, a templating agent and water to hydrothermal crystallization to obtain a directing agent A comprising seed crystals;
b) preparing a mixture II formed by a phosphorus source, an aluminum source, a silicon source and water into silicon-phosphorus-aluminum dry glue B;
c) adding the silicon-phosphorus-aluminum dry glue B into the guiding agent A to obtain a mixture III;
d) and carrying out hydrothermal treatment and hydrothermal crystallization on the mixture III to obtain the SAPO-34 molecular sieve.
Non-limiting examples of the silicon source according to one aspect of the present invention include at least one of silicate, white carbon, tetraalkyl silicate, silica sol, silicic acid, alkali metal silicate. The preferred silicon source is at least one of tetraalkyl silicate, silica, and silica sol.
According to one aspect of the invention, non-limiting examples of the source of phosphorus include at least one of phosphoric acid, triethyl phosphate, aluminophosphates, phosphorous acid, phosphates. The preferred phosphorus source is at least one of phosphoric acid, phosphate, phosphorous acid.
Non-limiting examples of aluminum sources according to one aspect of the invention include at least one of aluminum isopropoxide, aluminum phosphate, aluminum hydroxide, sodium aluminate, pseudoboehmite, alumina, aluminum trichloride. The preferred aluminum source is at least one of aluminum isopropoxide, pseudoboehmite, and alumina.
According to one aspect of the invention, non-limiting examples of templating agents include: tetraalkylammonium compound (including salts thereof), such as at least one of tetramethylammonium compound (including salts thereof), tetraethylammonium compound (including salts thereof), tetrapropylammonium compound (including salts thereof), and tetrabutylammonium compound (including salts thereof), cyclohexylamine, morpholine, di-n-propylamine, tripropylamine, triethylamine, diethylamine, triethanolamine, piperidine. The preferred templating agent is at least one of tetraethylammonium hydroxide, TEAOH, tetrapropylammonium bromide, TPA, triethylamine, diethylamine, morpholine.
According to an aspect of the present invention, the order of adding the silicon source, the phosphorus source, the aluminum source, the templating agent and the water in step a) is not particularly limited.
According to one aspect of the invention, the molar composition of the raw materials in the mixture I is: mR (Si)aAlbPc)O2Wherein R is a templating agent, m is the number of moles of templating agent, m is 0.03-1.0, a is 0.01-0.30, b is 0.30-0.60, c is 0.30-0.60, and the formula (a + b + c) is 1The method comprises the following steps of (1) preparing a silicon source, an aluminum source and a phosphorus source, wherein the silicon source is calculated by Si, the aluminum source is calculated by Al, and the phosphorus source is calculated by P; the aluminum source is calculated as Al: water 1: 5 to 60.
According to one aspect of the invention, the mixture I is selectively stirred and aged for 1-24 hours at room temperature, then is put into a crystallization kettle, and is subjected to hydrothermal crystallization for 0.1-12 hours at 180-220 ℃, preferably, the crystallization temperature is 190-210 ℃, and the crystallization time is 2-6 hours.
According to one aspect of the invention, the molar ratio of the substances in the mixture II is: (Si)aAlbPc)O20.01-0.30% of a, 0.30-0.60% of b, 0.30-0.60% of c, and the condition that a + b + c is 1 is satisfied, wherein the silicon source is calculated by Si, the aluminum source is calculated by Al, and the phosphorus source is calculated by P; the aluminum source is calculated as Al: water 1: 5 to 30.
According to an aspect of the present invention, the order of addition of the phosphorus source, the aluminum source, the silicon source and the water in step b) is not particularly limited.
According to one aspect of the invention, the preparation method of the silicon-phosphorus-aluminum dry glue B in the step B) is as follows: and (3) heating the mixture II to 80-100 ℃ under stirring, heating to evaporate part of water, and drying at 100-140 ℃ to obtain the silicon-phosphorus-aluminum dry glue B.
According to one aspect of the invention, the silicon-phosphorus-aluminum dry glue B is added into a guiding agent A solution to prepare a mixture III, and the guiding agent A and the silicon-phosphorus-aluminum dry glue B are mixed according to the proportion of Al in the mixture2O3And (2) the molar ratio is 1: (0.1 to 3).
According to one aspect of the invention, the silicon-phosphorus-aluminum dry glue B is ground or not ground.
According to one aspect of the invention, the mixture III is subjected to hydrothermal treatment at 140-170 ℃ for 0.1-12 hours, preferably at 150-170 ℃ for 0.5-4 hours.
According to one aspect of the invention, the hydrothermal crystallization temperature of the mixture III is 180-220 ℃, preferably 180-200 ℃, and the hydrothermal crystallization time is 2-48 hours, preferably 12-24 hours.
According to one aspect of the invention, after the end of the crystallization step, the mixture iii is subjected to any separation means conventionally known to separate the SAPO-34 product from the mixture obtained. The separation method includes, for example, a method of filtering, washing and drying the obtained mixture. Here, the filtering, washing and drying may be performed in any manner conventionally known in the art. As a specific example, as the filtration, for example, the obtained product mixture may be simply filtered with suction. Examples of the washing include washing with deionized water and/or ethanol. The drying temperature is, for example, 40 to 250 ℃, preferably 60 to 150 ℃, and the drying time is, for example, 8 to 30 hours, preferably 10 to 20 hours. The drying may be carried out under normal pressure or under reduced pressure.
According to one aspect of the present invention, the molecular sieve prepared according to the foregoing method may also be calcined, if desired, to remove the templating agent and any moisture and the like that may be present. The calcination can be carried out in any manner conventionally known in the art, for example, the calcination temperature is generally 300 to 800 ℃, preferably 400 to 650 ℃, and the calcination time is generally 1 to 10 hours, preferably 3 to 6 hours. In addition, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or oxygen.
According to one aspect of the invention, the molecular sieves prepared according to the foregoing methods can be formulated into molecular sieve catalyst compositions, as desired, particularly for industrial applications. The molecular sieve prepared according to the foregoing method is blended with a binder to form a slurry-like mixture, which is formed into useful shaped and sized particles by well-known techniques such as spray drying, pelletizing, extrusion, and the like.
Non-limiting examples of binders according to one aspect of the present invention include alumina, silica sol, or mixtures thereof.
According to one aspect of the invention, the molecular sieve or molecular sieve composition prepared according to the foregoing process can be used in an oxygenate to olefin reaction.
Non-limiting examples of oxygenates according to one aspect of the present invention include methanol, ethanol, n-propanol, isopropanol、C4-20Alcohols, methyl ethyl ether, dimethyl ether, diethyl ether, diisopropyl ether, formaldehyde, dimethyl carbonate, dimethyl ketone, or any combination thereof; preferably methanol, dimethyl ether, or any combination thereof. Methanol is more preferred.
According to one aspect of the invention, the olefins produced from the oxygenate typically have from 2 to 20 carbon atoms, preferably from 2 to 8 carbon atoms, more preferably from 2 to 6 carbon atoms, more preferably from 2 to 4 carbon atoms, and most preferably ethylene and/or propylene.
According to one aspect of the invention, the process for converting oxygenates to olefins is carried out in a reactor. The reactor may be a fixed bed, a fluidized bed (including a turbulent bed), preferably a continuous fluidized bed, most preferably a continuous high velocity fluidized bed. In a preferred embodiment, the continuous fluidized bed or high velocity fluidized bed comprises a reactor system, a regeneration system.
In accordance with one aspect of the invention, the best results are achieved when the conversion temperature used in the reactor system is controlled to a temperature of 200 to 700 deg.C, desirably 250 to 600 deg.C, and most desirably 300 to 500 deg.C. Lower temperatures generally result in lower reaction rates and the rate of formation of the desired olefin product is significantly slowed. However, at temperatures above 700 ℃, the process also does not produce optimal amounts of olefin product, and the rate of coke and light saturates formation on the catalyst becomes too fast.
According to one aspect of the invention, olefins will be formed in the reactor system over a wide range of pressures, including autogenous pressures. The pressure includes, but is not limited to, a pressure of 0.1kPa to 5MPa, desirably a pressure of 5kPa to 1MPa, and most desirably a pressure of 20kPa to 500 kPa. Pressures outside the above pressure ranges may also be used and are not excluded from the scope of the present invention. Lower and higher pressures can adversely affect selectivity, conversion, coke formation, and/or reaction rate; however, olefins can still be produced and therefore these pressure ranges are considered to be part of the present invention.
According to one aspect of the invention, for oxygen-containing compoundsThe weight space velocity WHSV of the conversion reaction is desirably high enough to maintain the catalyst in a fluidizable state under the reaction conditions and in the reactor's structure and design. WHSV is defined as the total weight of feedstock per hour per unit weight of catalyst in the reactor excluding any diluent added to the reactor. Generally, WHSV is in the range of l to 5000hr-1Preferably 2 to 3000hr-1More preferably 5 to 1500hr-1。
During the conversion of oxygenates to olefins, carbonaceous deposits accumulate on the catalyst used to promote the conversion reaction. In some cases, the accumulation of these carbonaceous deposits can result in a decrease in the catalytic ability of the oxygenate feed to light olefin conversion. In this case, the catalyst loses part of its activity. The catalyst is considered to be completely deactivated when the catalyst is no longer capable of converting the oxygenate to olefin product. As an optional step in the oxygenate to olefin reaction, a portion of the catalyst is withdrawn from the reactor and at least a portion of the catalyst withdrawn from the reactor is regenerated in a regeneration unit. By regeneration, it is meant that the carbonaceous deposits are at least partially removed from the catalyst. The regenerated catalyst, which may or may not be cooled, is then returned to the reactor. Desirably, the amount of the portion of the catalyst withdrawn for regeneration is 0.1 to 99% of the amount of the catalyst exiting the reactor. More desirably, the extraction is from 0.2% to 50%, most desirably from 0.5% to 5%.
The catalyst may be regenerated in any process, batch, continuous, semi-continuous, or a combination thereof. Continuous catalyst regeneration is a desirable process. Desirably, the catalyst is regenerated to a level of 0.01 to 15 wt% of the amount of carbon deposit. The regeneration temperature of the catalyst should be 250 to 750 ℃, and is desirably 500 to 700 ℃.
In the invention, the crystalline phase of the molecular sieve is carried out on a Bruker D8 polycrystalline X-ray diffraction (XRD) instrument, a graphite monochromator is used, a Cu-Ka ray source is used (Ka 1 wavelength lambda is 0.15406nm), the scanning angle 2 theta is 5-50 degrees, and the scanning speed is 1 degree/min.
In the invention, the morphology of the molecular sieve product is determined by a Scanning Electron Microscope (SEM). The Scanning Electron Microscope (SEM) picture of the molecular sieve is determined by a Nova NanoSEM 450 type scanning electron microscope, a sample is firstly ground to 200-400-mesh powder, the powder is fixed by double-sided conductive adhesive and then is tested in a high vacuum state, and the emission voltage of the microscope is 200 kV.
The invention is further illustrated by the following examples.
Comparative example 1
12.1 g of gamma-Al2O3And 30.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 35.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperature to form a uniform solution c; while stirring, 31 g of triethylamine and 3.0 g of silica Sol (SiO) were added to c in this order240 percent of mass content) and 27.0 g of deionized water, and fully stirring to obtain a mixture I; the mixture was crystallized at 200 ℃ for 24 hours, the product was centrifuged to give a solid product which was dried overnight in an oven at 110 ℃ and the resulting molecular sieve product weighed 19.6 grams.
Comparative example 2
12.1 g of gamma-Al2O3And 20.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 10.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperature to form a uniform solution c; to c was added 3.0 g of silica Sol (SiO)240 percent of mass content) and 15.0 g of deionized water, fully stirring, heating to 90 ℃, gradually increasing the viscosity of the solution along with the evaporation of water to form a colloid, and drying the colloid at 120 ℃. Grinding the dried colloid, placing the ground colloid on the upper part of a crystallization kettle, placing 31 g of triethylamine and 50 g of water at the bottom of the crystallization kettle, and carrying out gas phase crystallization at 200 ℃ for 24 hours to recover the product.
[ example 1 ]
Step a), 12.1 g of gamma Al2O3And 30.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 35.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperatureForming a homogeneous solution c; while stirring, 31 g of triethylamine and 3.0 g of silica Sol (SiO) were added to c in this order240 percent of mass content) and 27.0 g of deionized water, and fully stirring to obtain a mixture I; crystallizing the mixture I at 200 ℃ for 6 hours to obtain the directing agent A containing large-grain new crystals.
Step b), 12.1 g of gamma-Al2O3And 20.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 10.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperature to form a uniform solution c; while stirring, 3.0 g of silica Sol (SiO) was added to c240 percent of mass content) and 15.0 g of deionized water, fully stirring to obtain a mixture II, heating the mixture to 90 ℃, gradually increasing the viscosity of the solution along with the evaporation of water to form a colloid, and drying the colloid at 120 ℃ to obtain the silicon-phosphorus-aluminum dry glue B.
Step c), weighing 15.0 g of aluminum phosphate dry glue B ground by a ball mill, and adding the aluminum phosphate dry glue B into the guiding agent A to obtain a mixture III;
and d), putting the mixture III into a crystallization kettle, performing hydrothermal treatment at 170 ℃ for 3 hours, then crystallizing at 200 ℃ for 24 hours, performing centrifugal separation on the product, and drying in an oven at 110 ℃ for 24 hours to obtain a molecular sieve product, wherein the weight of the molecular sieve product is 30.1 g.
[ example 2 ]
Same as [ example 1 ], but 5.0 g of aluminum phosphate xerogel B is weighed and 23.1 g of final product is weighed.
[ example 3 ]
Same as [ example 1 ], but 10.0 g of aluminum phosphate gel B was weighed and the final product weighed 28.4 g.
[ example 4 ]
Same as [ example 1 ], but 20.0 g of aluminum phosphate gel B was weighed and the final product weighed 36.7 g.
[ example 5 ]
Same as [ example 1 ], except that the mixture I was crystallized at 210 ℃ for 4 hours, the aluminum phosphate dried gel B was added to the directing agent a, and then it was hydrothermally treated at 160 ℃ for 1 hour, and the final product weighed 31.2 g.
[ example 6 ]
Step a), 12.1 g of gamma Al2O3And 30.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 35.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperature to form a uniform solution c; while stirring was maintained, 15.0 g of triethylamine, 25.0 g of tetraethylammonium hydroxide and 3.0 g of silica Sol (SiO) were added to c in this order240 percent of mass content) and 27.0 g of deionized water, and fully stirring to obtain a mixture I; crystallizing the mixture I at 200 ℃ for 4 hours to obtain the directing agent A.
Step b), 12.1 g of gamma-Al2O3And 20.0 g of deionized water are mixed uniformly to form a solution a; 23.1 grams of phosphoric acid (85% by weight), 10.0 grams of deionized water were mixed well to form solution b; a and b are mixed and stirred for 2 hours at room temperature to form a uniform solution c; while stirring, 3.0 g of silica Sol (SiO) was added to c240 percent of mass content) and 15.0 g of deionized water, fully stirring to obtain a mixture II, heating the mixture to 90 ℃, gradually increasing the viscosity of the solution along with the evaporation of water to form a colloid, and drying the colloid at 120 ℃ to obtain the silicon-phosphorus-aluminum dry glue B.
And c), weighing 15.0 g of aluminum phosphate dry gel B ground by a ball mill, and adding the aluminum phosphate dry gel B into the guiding agent A to obtain a mixture III.
And d), putting the mixture III into a crystallization kettle, performing hydrothermal treatment at 150 ℃ for 1 hour, then crystallizing at 195 ℃ for 18 hours, performing centrifugal separation on the product, and drying in an oven at 110 ℃ for 24 hours to obtain a molecular sieve product, wherein the weight of the molecular sieve product is 27.2 g.
[ example 7 ]
Same as [ example 6 ], but 20.0 g of aluminum phosphate gel B was weighed and the final product weighed 35.6 g.
[ example 8 ]
XRD characterization of the products obtained in examples 1-7 and comparative examples 1-2 was performed, and as shown in FIG. 1, the results indicate that the products are SAPO-34 molecular sieves, and the samples in examples 1-7 and comparative example 1 have good crystallinity, and the sample in comparative example 2 has poor crystallinity.
[ example 9 ]
The SAPO-34 molecular sieves obtained in examples 1 to 7 and comparative examples 1 to 2 were evaluated in a fixed bed under the following reaction conditions: 2.0g of catalyst, pure methanol feeding, preheating temperature of 200 ℃, reaction temperature of 460 ℃, and space velocity (WHSV) of 6.0h-1And the pressure is 0.1 MPa. The results are shown in Table 1.
TABLE 1
Sample (I)
C2 ＝+C3 ＝/％
Example 1
81.8
Example 2
82.4
Example 3
82.7
Example 4
82.3
Example 5
82.2
Example 6
83.8
Example 7
83.5
Comparative example 1
82.1
Comparative example 2
78.4