CN109174169B - Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof - Google Patents

Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof Download PDF

Info

Publication number
CN109174169B
CN109174169B CN201811214739.7A CN201811214739A CN109174169B CN 109174169 B CN109174169 B CN 109174169B CN 201811214739 A CN201811214739 A CN 201811214739A CN 109174169 B CN109174169 B CN 109174169B
Authority
CN
China
Prior art keywords
molecular sieve
sieve catalyst
catalyst
modified
aqueous solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811214739.7A
Other languages
Chinese (zh)
Other versions
CN109174169A (en
Inventor
吕宏安
何观伟
袁岚
张芳
王新星
崔楼伟
卞雯
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xi'an Origin Chemical Technologies Co ltd
Original Assignee
Xi'an Origin Chemical Technologies Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xi'an Origin Chemical Technologies Co ltd filed Critical Xi'an Origin Chemical Technologies Co ltd
Priority to CN201811214739.7A priority Critical patent/CN109174169B/en
Publication of CN109174169A publication Critical patent/CN109174169A/en
Application granted granted Critical
Publication of CN109174169B publication Critical patent/CN109174169B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/06—Washing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/10—Heat treatment in the presence of water, e.g. steam
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y02P30/40—Ethylene production

Abstract

The invention discloses a modified molecular sieve catalyst for preparing ethylene by ethanol dehydration, which takes HZSM-5 molecular sieve powder and macroporous pseudo-boehmite powder as raw materials to prepare an unmodified strip molecular sieve catalyst, and then sequentially uses Na2CO3The aqueous solution and the citric acid aqueous solution are subjected to alkali modification and acid modification, and are dried and roasted to obtain the aqueous solution; the invention also discloses application of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration. In the preparation and modification process of the catalyst, a stirring process is not needed, the preparation process is simplified, the weak acid amount on the surface of the catalyst is greatly improved, and the medium-strong acid amount is reduced, so that the catalytic performance of the modified molecular sieve catalyst on the reaction of preparing ethylene by ethanol dehydration is improved, the conversion rate of raw material ethanol and the selectivity of product ethylene are improved, and the service life of the modified molecular sieve catalyst is prolonged; the modified molecular sieve catalyst is simple to apply in the preparation of ethylene by ethanol dehydration and is suitable for popularization.

Description

Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof
Technical Field
The invention belongs to the technical field of catalyst preparation, and particularly relates to a modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof.
Background
Ethylene is one of the most basic raw materials in the organic chemical industry, and is mainly used for polymer materials such as synthetic resins, rubber, fibers, coatings, adhesives, surfactants and the like. Meanwhile, the modern ethylene industry produces ethylene and also obtains byproducts such as propylene, butadiene, benzene, xylene and the like, which are also important raw materials for manufacturing related synthetic materials. The main raw materials for the industrial production of ethylene at present come from two routes: first, the light hydrocarbon of natural gas processing factory: such as ethane, propane, butane, etc.; secondly, the processed products of the oil refinery: such as refinery gas, gasoline, diesel, etc.; the raw materials of the two ways can be cracked to obtain ethylene.
Today, the cost of ethylene production in petroleum routes is increasing and the price of ethylene is also increasing with increasing prices of petroleum resources. Under the background, the development of biological energy sources to prepare ethylene by utilizing renewable biomass resources becomes a necessary trend in the development of the ethylene industry at present and even later. Wherein, the ethanol is used as a raw material, and the ethanol dehydration process is utilized to prepare the ethylene, so that the industrial application is realized. As early as the first world war, fixed bed dehydration processes were developed and put into production in Europe; industrial devices are successively built in brazil, india and other countries in the last 60 years, 2-10 Kt ethylene is produced in the year at the time of scale, and the most widely used catalyst for preparing ethylene by ethanol dehydration is an active alumina catalyst. In the last 70 th century, the world energy crisis caused the price of petroleum to rise, and the process for producing ethylene by ethanol dehydration has attracted the attention of developed countries in the west. In addition to research on the process, various countries also show great enthusiasm in the field of catalyst research. In the last 80 th century, Syndol catalyst was developed by Halcon corporation, and the catalyst has good overall performance, but has the disadvantages of strict requirements on reaction conditions, high reaction temperature, high concentration requirement on ethanol raw materials, and high overall energy consumption; rigium et al use a 0.3mm to 1.0mm granular alumina dehydration catalyst, where the ethanol conversion rate reaches 99% at a reaction temperature of above 420 ℃, but the catalyst reaction temperature is high.
In the last 80 th century, researchers carried out a great deal of research on the ethanol dehydration performance of the HZSM-5 type molecular sieve developed by Mobil corporation in the united states, and as a result, the HZSM-5 type molecular sieve was found to show high activity in the reaction of preparing ethylene by ethanol dehydration due to its special three-dimensional pore structure, large specific surface area and unique surface acidity, and its main advantages include: excellent thermal stability, acid resistance, shape selectivity, water vapor stability and hydrophobicity. However, one of the main disadvantages of the HZSM-5 molecular sieve is that the acidity is strong, the carbon deposition rate of the catalyst is high due to a severe ethylene polymerization side reaction, and the pores in the molecular sieve are basically micropores and have limited carbon-containing capacity, so that the generated ethylene can further undergo a polymerization reaction at the acidic site of the catalyst to generate high-carbon compounds, which can rapidly accumulate in the pores to cause the pore channels of the catalyst to be blocked, thereby rapidly deactivating the catalyst. After partial dealuminization and desilication treatment is carried out on the molecular sieve through acid-base modification, the acid distribution on the surface of the molecular sieve can be changed, and the strong acid content on the surface of the molecular sieve is reduced; meanwhile, more mesoporous structures are generated, the pore volume of the mesoporous part is increased, and the carbon holding capacity of the catalyst is greatly improved, so that the carbon deposition rate of the catalyst can be reduced, and the activity stability of the molecular sieve dehydration catalyst is greatly improved.
At present, the acid-base modification process of the HZSM-5 molecular sieve has various defects: the method is mainly characterized in that a modification process is relatively complex, generally, acid-base modification is carried out on molecular sieve powder firstly, because raw materials exist in a powder form, in order to ensure the uniformity degree of modification, a mechanical stirring mode is adopted, so that the energy consumption in the modification process is high, the modified molecular sieve powder can be formed through the processes of drying, roasting and the like after modification, and then the modified molecular sieve powder is used as the raw material to be bonded, extruded, dried and roasted with macroporous pseudo-boehmite powder, so that the acid-base modified molecular sieve catalyst can be prepared. The whole process goes through the processes of drying and roasting twice, and some molecular sieves are further modified by superheated steam, so that the process is complex and the preparation cost is increased. In patent CN106215970A, Zhang Ruizhen et al performed modification research on ZSM-5 molecular sieve by using alkali/steam double modification method, and the molecular sieve after alkali treatment removed framework silicon, expanded framework pore structure, formed partial mesopores, and improved carbon capacity; the acidic proportion is modulated after the steam treatment, the carbon deposition resistance of the catalyst is enhanced, and the modified catalyst is used for aromatization of low-carbon hydrocarbonsIn the reaction, the stability of the catalyst is improved, and the service life is prolonged; however, in the modification process, after alkali modification, steam is required to be used for further modification at the temperature of 200-600 ℃, so that the energy consumption is high, and the process is complex. Lvjiang et al, China university of Petroleum, examined the effects of alkali treatment, first alkali treatment and then two-step acid treatment on the physicochemical properties of HZSM-5 molecular sieve and the alkylation reaction performance of benzene and methanol, wherein the alkali used is Na with a certain concentration2CO3The acid is HCl aqueous solution with certain concentration. The results show that: after alkali treatment with proper concentration, two-step acid treatment is carried out, on one hand, non-framework silicon-aluminum species of the molecular sieve can be removed, and the particles of the molecular sieve are more uniform; on the other hand, the strong acid center of the molecular sieve is reduced, the carbon deposition inactivation rate of the catalyst is reduced, and the benzene conversion rate is improved by more than 15%. The modification process is also complicated because the catalyst prepared by the alkali treatment needs two-step acid treatment to have higher reaction activity. In patent CN107876082A, liu bin et al performed alkali modification on a ZSM-5 molecular sieve, and the alkali-modified ZSM-5 molecular sieve has a low micropore ratio of its crystal grains, expands the range of micropores to mesopores and macropores (5 to 110nm) and has higher crystallinity, and modulates the acidity and pore structure of the molecular sieve through modification. The catalyst prepared by the molecular sieve is used in hexene aromatization reaction, and can effectively delay deactivation caused by coking, thereby prolonging the service life of the catalyst. However, the molecular sieve catalyst uses expensive organic alkali such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and the like in the modification, so that the preparation cost of the modified catalyst is high.
Disclosure of Invention
The invention aims to solve the technical problem of providing a modified molecular sieve catalyst for preparing ethylene by ethanol dehydration aiming at the defects of the prior art. The modified molecular sieve catalyst is prepared by sequentially carrying out primary alkali modification and primary acid modification on an unmodified molecular sieve catalyst, the modification uniformity of HZSM-5 molecular sieve powder is ensured without using a stirring process in the modification process, the weak acid amount on the surface of the catalyst is greatly improved, and the medium-strong acid amount is reduced, so that the catalytic performance of the modified molecular sieve catalyst on the reaction of preparing ethylene by ethanol dehydration is improved, the conversion rate of raw material ethanol and the selectivity of product ethylene are improved, and the service life of the modified molecular sieve catalyst is prolonged.
In order to solve the technical problems, the invention adopts the technical scheme that: a modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized by being prepared by the following method:
step one, uniformly mixing HZSM-5 molecular sieve powder, macroporous pseudo-boehmite powder and sesbania powder to obtain a mixture, adding a sodium carboxymethylcellulose aqueous solution into the mixture, uniformly mixing, rolling, sequentially extruding and drying, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the molar ratio of silicon to aluminum is 50-60, and the specific surface area is not less than 200m2Na/g, pore volume not less than 0.15mL/g2The mass percentage content of O is not more than 0.1 percent; the specific surface area of the macroporous pseudo-boehmite powder is not less than 250m2Na/g, pore volume of not less than 1.0mL/g2O is not more than 0.05 percent by mass, and Al2O3The mass percentage content of the compound is 70 percent; the sesbania powder in the unmodified strip molecular sieve catalyst accounts for 3.0 percent by mass; the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 0.5 percent, the adding volume of the sodium carboxymethyl cellulose aqueous solution is 34.5 to 36.5 percent of the mass of the mixture, the unit of the volume is mL, and the unit of the mass is g;
step two, adding the unmodified strip molecular sieve catalyst obtained in the step one into Na2CO3Heating the aqueous solution to perform alkali modification, taking out and drying to obtain an alkali-modified strip molecular sieve catalyst;
step three, adding the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a citric acid aqueous solution for acid modification, taking out and drying to obtain an acid-modified strip-shaped molecular sieve catalyst, and roasting the acid-modified strip-shaped molecular sieve catalyst to obtain a modified molecular sieve catalyst; HZSM-5 molecular sieve in the modified molecular sieve catalystThe mass percentage of the powder is 60-80 percent, and Al2O3The mass percentage of the component (A) is 20-40%.
Firstly, using HZSM-5 molecular sieve powder and macroporous pseudo-boehmite powder as raw materials to prepare an unmodified molecular sieve catalyst, and then sequentially immersing the unmodified molecular sieve catalyst into Na2CO3In the solution and the citric acid solution, the modified molecular sieve catalyst is obtained by respectively carrying out primary alkali modification and primary acid modification, because the unmodified molecular sieve catalyst is directly modified, the modification process does not need to use a stirring process to ensure the uniformity of modification of HZSM-5 molecular sieve powder, the preparation process is simplified, the aim of adjusting the surface acidity of the catalyst can be fulfilled, the weak acid amount is greatly improved, the medium-strong acid amount is reduced, because the reaction for preparing ethylene by ethanol dehydration is a reaction controlled by the catalytic activation of a weak acid center on the surface of the catalyst, the catalytic performance of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is greatly improved due to the increase of the weak acid amount on the surface of the modified molecular sieve catalyst, the conversion rate of raw material ethanol and the selectivity of product ethylene are further improved, and the defect that high-carbon compounds are formed by side reactions such as further polymerization of the generated by strong acid and the like to block catalyst pore channels is avoided, the carbon capacity and activity stability of the modified molecular sieve catalyst are enhanced.
The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized in that the unmodified bar-shaped molecular sieve catalyst and Na are obtained in the alkali modification process in the step two2CO3The mass ratio of the aqueous solution is 1: (20 to 30) said Na2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent.
The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized in that the mass ratio of the strip molecular sieve catalyst subjected to alkali modification to the citric acid aqueous solution in the acid modification process in the step three is 1: (20-30), the preparation raw material of the citric acid aqueous solution is citric acid monohydrate, and the citric acid monohydrate is an analytical reagent.
The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized in that the temperature of alkali modification and acid modification in the second step and the third step is 50-70 ℃, and the time is 2-4 hours. The temperature conditions of the alkali modification and the acid modification are mild, the time consumption is short, and the industrial application is facilitated.
The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized in that the drying temperature in the first step, the drying temperature in the second step and the drying time in the third step are 100-120 ℃, and the drying time is 2-4 hours. Drying within the temperature and time range can ensure that free water in the modified molecular sieve catalyst is fully removed, and reduce the influence of the free water on the performance of the modified molecular sieve catalyst.
The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized in that the roasting treatment process in the third step is as follows: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h. The molecular sieve catalyst obtained by roasting treatment can ensure the sufficient decomposition of the residual template agent of the molecular sieve and the activity of the components of the molecular sieve, can also ensure the sufficient decomposition of extrusion aids and pore-forming agents such as sesbania powder, sodium carboxymethylcellulose and the like added during preparation, ensures that a pore structure with certain distribution is formed in the catalyst, and facilitates the adsorption, reaction and desorption of molecules such as ethanol, water, ethylene and the like in the application process.
In addition, the invention also provides application of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration, which is characterized by comprising the following steps:
filling a modified molecular sieve catalyst into a fixed bed reactor, introducing nitrogen into the fixed bed reactor, and heating for activation;
and step two, introducing an ethanol water solution into the fixed bed reactor to carry out ethanol dehydration reaction to obtain ethylene.
The application is characterized in that the mass concentration of the ethanol aqueous solution in the step two is 50%, and the airspeed of the ethanol aqueous solution is 1.5h-1Introduction pressure of ethanol aqueous solutionThe force is 0.25MPa, and the temperature of the ethanol dehydration reaction is 240-350 ℃.
In the application process of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration, the modified molecular sieve catalyst has higher catalytic activity, better activity stability and longer service life, so that the efficiency of preparing ethylene by ethanol dehydration is increased, the regeneration frequency of the catalyst is reduced, and the economic benefit is improved.
Compared with the prior art, the invention has the following advantages:
1. the invention prepares the unmodified molecular sieve catalyst, and then carries out primary alkali modification and primary acid modification in sequence to obtain the modified molecular sieve catalyst, saves the stirring process of HZSM-5 molecular sieve powder in the acid-base modification process, thereby adjusting the acid distribution on the surface of the catalyst, greatly improving the weak acid amount, reducing the medium-strong acid amount, because the reaction for preparing ethylene by ethanol dehydration is a reaction controlled by the catalytic activation of weak acid centers on the surface of the catalyst, the increase of the weak acid amount on the surface of the modified molecular sieve catalyst greatly improves the catalytic performance of the modified molecular sieve catalyst on the reaction for preparing ethylene by ethanol dehydration, further improves the conversion rate of the raw material ethanol and the selectivity of the product ethylene, simultaneously avoids the defect that the strong acid causes the generated ethylene to further generate side reactions such as polymerization and the like to form high-carbon compounds to block the pore channels of the catalyst, and enhances the carbon capacity and the activity stability of the modified molecular sieve catalyst.
2. In the catalyst modification process, a preparation process of firstly preparing an unmodified catalyst and then carrying out acid-base modification on the catalyst is adopted, meanwhile, the acid is a citric acid solution with weak acidity, and the base is Na with weak alkalinity2CO3The alkali liquor and the prepared catalyst have less change of physical and chemical properties than those of the catalyst before modification, so that the surface acidity of the catalyst is changed while the physical structure of the catalyst is not greatly changed, the problem that the selectivity of ethylene is reduced due to the fact that the ethylene generated by reaction is polymerized and generates a high-carbon compound is further avoided, and the selectivity of the ethylene is improved.
3. The catalyst is adopted in the modification processIs commonly used and has lower price of Na2CO3And the citric acid monohydrate is respectively used as the preparation raw materials of the alkali modifier and the acid modifier, so that the use of expensive organic alkali modified raw materials such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and the like is avoided, and the preparation cost of the catalyst is further reduced.
4. The molecular sieve catalyst modified by the acid does not need to be roasted, and the obtained modified molecular sieve catalyst does not need to be adhered and extruded into strips, so that the preparation method is further simplified, and the preparation cost is reduced.
5. In the application process of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration, the modified molecular sieve catalyst has higher catalytic activity, better activity stability and longer service life, so that the efficiency of preparing ethylene by ethanol dehydration is increased, the regeneration frequency of the catalyst is reduced, and the economic benefit is improved.
The technical solution of the present invention is further described in detail by examples below.
Detailed Description
The modified molecular sieve catalyst of the present invention is described in detail by way of examples 1 to 6.
Example 1
The modified molecular sieve catalyst of this example was prepared by the following method:
uniformly mixing 70.0g of HZSM-5 molecular sieve powder, 43.0g of macroporous pseudo-boehmite powder and 3.5g of sesbania powder for 20min to obtain a mixture, adding 40.2mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruder to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in an oven at the temperature of 110 ℃ for 2h, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 60, and the specific surface area is 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface of the macroporous pseudo-boehmite powderProduct of 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of the unmodified bar-shaped molecular sieve catalyst obtained in the step one into 2750.0g of Na with the concentration of 0.2N2CO3Heating the aqueous solution in a three-neck flask at 50 ℃ for 4h for alkali modification, taking out the aqueous solution, and drying the aqueous solution at 110 ℃ for 2h to obtain an alkali-modified strip molecular sieve catalyst; the Na is2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 2500.0g of 0.2N citric acid aqueous solution, heating for 4h at 50 ℃ for acid modification, taking out, drying for 2h at 110 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 70% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 30%.
Comparative example 1
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
step one, uniformly mixing 70.0g of HZSM-5 molecular sieve powder, 43.0g of macroporous pseudo-boehmite powder and 3.5g of sesbania powder for 20min to obtain a mixture, adding 40.2mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, and extruding on a strip extruder to be straightPutting the cylindrical catalyst with the diameter of 2.0mm into an oven, drying for 2 hours at the temperature of 110 ℃, and naturally cooling to obtain a strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 60, and the specific surface area is 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface area of the macroporous pseudo-boehmite powder is 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent;
step two, putting 110.0g of the strip molecular sieve catalyst obtained in the step one into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 70% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 30%.
Example 2
The modified molecular sieve catalyst of this example was prepared by the following method:
uniformly mixing 80.0g of HZSM-5 molecular sieve powder, 28.6g of macroporous pseudo-boehmite powder and 3.4g of sesbania powder for 20min to obtain a mixture, adding 39.8mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding the mixture on a strip extruder to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in an oven at the temperature of 110 ℃ for 2h, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 60, and the specific surface area is 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface area of the macroporous pseudo-boehmite powder is 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of the unmodified bar-shaped molecular sieve catalyst obtained in the step one into 3300.0g of Na with the concentration of 0.2N2CO3Heating the aqueous solution in a three-neck flask at the temperature of 70 ℃ for 2h for alkali modification, taking out the aqueous solution, and drying the aqueous solution at the temperature of 120 ℃ for 4h to obtain an alkali-modified strip molecular sieve catalyst; the Na is2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 3000.0g of 0.2N citric acid aqueous solution, heating for 2h at 70 ℃ for acid modification, taking out, drying for 4h at 120 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 80% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 20%.
Comparative example 2
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
step one, uniformly mixing 80.0g of HZSM-5 molecular sieve powder, 28.6g of macroporous pseudo-boehmite powder and 3.4g of sesbania powder for 20min to obtain a mixture, then adding 39.8mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruding machine to form a cylindrical catalyst with the diameter of 2.0mm, placing the cylindrical catalyst in an oven, drying for 2h at the temperature of 110 ℃,naturally cooling to obtain the strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 60, and the specific surface area is 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface area of the macroporous pseudo-boehmite powder is 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent;
step two, adding 110.0g of the strip molecular sieve catalyst obtained in the step one into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 80% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 20%.
Example 3
The modified molecular sieve catalyst of this example was prepared by the following method:
step one, uniformly mixing 60.0g of HZSM-5 molecular sieve powder, 57.1g of macroporous pseudo-boehmite powder and 3.7g of sesbania powder for 20min to obtain a mixture, then adding 44.1mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding into a cylindrical catalyst with the diameter of 2.0mm on a strip extruding machine, placing the cylindrical catalyst in an oven, drying for 3h at the temperature of 100 ℃, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 50, and the specific surface area is 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface area of the macroporous pseudo-boehmite powder is 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of the unmodified bar-shaped molecular sieve catalyst obtained in the step one into 2200.0g of Na with the concentration of 0.2N2CO3Heating the aqueous solution in a three-neck flask at the temperature of 60 ℃ for 3h for alkali modification, taking out the aqueous solution, and drying the aqueous solution at the temperature of 100 ℃ for 3h to obtain an alkali-modified strip molecular sieve catalyst; the Na is2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 2000.0g of citric acid aqueous solution with the concentration of 0.2N, heating for 3h at the temperature of 60 ℃ for acid modification, taking out, drying for 3h at the temperature of 100 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 60% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 40%.
Comparative example 3
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
step one, uniformly mixing 60.0g of HZSM-5 molecular sieve powder, 57.1g of macroporous pseudo-boehmite powder and 3.7g of sesbania powder for 20min to obtain a mixture, then adding 44.1mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding into a cylindrical catalyst with the diameter of 2.0mm on a strip extruding machine, placing the cylindrical catalyst in an oven, drying for 3h at the temperature of 100 ℃, and naturally cooling to obtain a strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, and the molar ratio of silicon to aluminum is50, specific surface area 210m2Per g, pore volume of 0.18mL/g, Na2The mass percentage of O is 0.05 percent; the specific surface area of the macroporous pseudo-boehmite powder is 260m2Per g, pore volume of 1.10mL/g, Na20.03 percent of O and Al2O3The mass percentage content of the compound is 70 percent;
step two, putting 110.0g of the strip molecular sieve catalyst obtained in the step one into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 60% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 40%.
Example 4
The modified molecular sieve catalyst of this example was prepared by the following method:
uniformly mixing 70.0g of HZSM-5 molecular sieve powder, 43.0g of macroporous pseudo-boehmite powder and 3.5g of sesbania powder for 20min to obtain a mixture, adding 40.2mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruding machine to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in an oven at the temperature of 100 ℃ for 3h, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.1%; the specific surface area of the macroporous pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na20.05 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of unmodified strip molecular sieve catalyst obtained in the step one2750.0g of 0.2N Na were contained2CO3Heating the aqueous solution in a three-neck flask at 50 ℃ for 4h for alkali modification, taking out the aqueous solution, and drying the aqueous solution at 110 ℃ for 3h to obtain an alkali-modified strip molecular sieve catalyst; the Na is2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 2500.0g of 0.2N citric acid aqueous solution, heating for 4h at 50 ℃ for acid modification, taking out, drying for 3h at 110 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 70% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 30%.
Comparative example 4
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
uniformly mixing 70.0g of HZSM-5 molecular sieve powder, 43.0g of macroporous pseudo-boehmite powder and 3.5g of sesbania powder for 20min to obtain a mixture, adding 40.2mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruding machine to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in a drying oven at the temperature of 100 ℃ for 3h, and naturally cooling to obtain a strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.1%; the large holeThe specific surface area of the pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na20.05 percent of O and Al2O3The mass percentage content of the compound is 70 percent;
step two, putting 110.0g of the strip molecular sieve catalyst obtained in the step one into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 70% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 30%.
Example 5
The modified molecular sieve catalyst of this example was prepared by the following method:
uniformly mixing 80.0g of HZSM-5 molecular sieve powder, 28.6g of macroporous pseudo-boehmite powder and 3.4g of sesbania powder for 20min to obtain a mixture, adding 39.8mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruding machine to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in an oven at the temperature of 120 ℃ for 4h, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.1%; the specific surface area of the macroporous pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na20.05 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of the unmodified bar-shaped molecular sieve catalyst obtained in the step one into 3300.0g of Na with the concentration of 0.2N2CO3Heating the aqueous solution in a three-neck flask at 70 deg.CCarrying out alkali modification for 2h, taking out and drying for 4h at the temperature of 120 ℃ to obtain the alkali-modified strip molecular sieve catalyst; the Na is2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 3000.0g of 0.2N citric acid aqueous solution, heating for 2h at 70 ℃ for acid modification, taking out, drying for 4h at 120 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 80% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 20%.
Comparative example 5
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
uniformly mixing 80.0g of HZSM-5 molecular sieve powder, 28.6g of macroporous pseudo-boehmite powder and 3.4g of sesbania powder for 20min to obtain a mixture, adding 39.8mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding on a strip extruding machine to form a cylindrical catalyst with the diameter of 2.0mm, drying the cylindrical catalyst in a drying oven at the temperature of 120 ℃ for 4h, and naturally cooling to obtain a strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.10 percent; the specific surface area of the macroporous pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na2The mass percentage of O is 0.05％，Al2O3The mass percentage content of the compound is 70 percent;
step two, adding 110.0g of the strip molecular sieve catalyst obtained in the step one into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 80% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 20%.
Example 6
The modified molecular sieve catalyst of this example was prepared by the following method:
step one, uniformly mixing 60.0g of HZSM-5 molecular sieve powder, 57.1g of macroporous pseudo-boehmite powder and 3.7g of sesbania powder for 20min to obtain a mixture, then adding 44.1mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding into a cylindrical catalyst with the diameter of 2.0mm on a strip extruding machine, placing the cylindrical catalyst in an oven, drying for 3h at the temperature of 100 ℃, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.1%; the specific surface area of the macroporous pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na20.05 percent of O and Al2O3The mass percentage content of the compound is 70 percent; the mass content of sesbania powder in the unmodified molecular sieve catalyst is 3.0 percent;
step two, adding 110.0g of the unmodified bar-shaped molecular sieve catalyst obtained in the step one into 2200.0g of Na with the concentration of 0.2N2CO3Heating the aqueous solution in a three-neck flask at the temperature of 60 ℃ for 3h for alkali modification, taking out the aqueous solution, and drying the aqueous solution at the temperature of 120 ℃ for 4h to obtain an alkali-modified strip molecular sieve catalyst; said N isa2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent;
step three, adding 100.0g of the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a three-neck flask containing 2000.0g of citric acid aqueous solution with the concentration of 0.2N, heating for 3h at the temperature of 60 ℃ for acid modification, taking out, drying for 3h at the temperature of 100 ℃ to obtain an acid-modified strip-shaped molecular sieve catalyst, and then placing the acid-modified strip-shaped molecular sieve catalyst into a muffle furnace for roasting treatment to obtain a modified molecular sieve catalyst; the preparation raw material of the citric acid aqueous solution is citric acid monohydrate which is an analytical reagent; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 60% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 40%.
Comparative example 6
The modified molecular sieve catalyst of this comparative example was prepared by the following method:
step one, uniformly mixing 60.0g of HZSM-5 molecular sieve powder, 57.1g of macroporous pseudo-boehmite powder and 3.7g of sesbania powder for 20min to obtain a mixture, then adding 44.1mL of sodium carboxymethylcellulose aqueous solution with the mass concentration of 0.5% into the mixture, uniformly mixing, rolling for 40min, extruding into a cylindrical catalyst with the diameter of 2.0mm on a strip extruding machine, placing the cylindrical catalyst in an oven, drying for 3h at the temperature of 100 ℃, and naturally cooling to obtain a strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the silica-alumina molar ratio is 55, and the specific surface area is 200m2Per g, pore volume of 0.15mL/g, Na2The mass percentage of O is 0.1%; the specific surface area of the macroporous pseudo-boehmite powder is 250m2A pore volume of 1.0mL/g, Na20.05 percent of O and Al2O3The mass percentage content of the compound is 70 percent;
step two, mixing 110.0g of the strip molecular sieve catalyst obtained in the step one is put into a muffle furnace for roasting treatment to obtain a molecular sieve catalyst; the roasting treatment process comprises the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h; the modified molecular sieve catalyst contains 60% of HZSM-5 molecular sieve powder and Al2O3The mass percentage of (B) is 40%.
(1) The modified molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the molecular sieve catalysts prepared in comparative examples 1 to 6 of the present invention were tested for surface acidity, specific surface area, mesoporous pore volume and average pore diameter, wherein the method for testing surface acidity is NH3TPD method using a full-automatic temperature programmed chemical adsorption apparatus of Micromeritics AUTOCHEM 2920 manufactured by Mac USA, and a full-automatic specific surface area, mesoporous pore volume and average pore diameter analyzer of Nova 4200e manufactured by Quantachrome USA, the results of which are shown in tables 1 and 2 below.
Table 1 surface area, mesoporous pore volume, and average particle size of the molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the modified molecular sieve catalysts prepared in comparative examples 1 to 6
Figure BDA0001833263560000181
Figure BDA0001833263560000191
As can be seen from table 1, the specific surface area, the mesoporous pore volume, and the average pore diameter of the modified molecular sieve catalysts obtained through acid-base modification in examples 1 to 6 of the present invention are slightly larger than those of the molecular sieve catalysts prepared in comparative examples 1 to 6, which correspond to the specific surface area, the mesoporous pore volume, and the average pore diameter, which are obtained in comparative examples 1 to 6, respectively, indicating that part of the microporous structures inside the catalysts are fused during the acid-base modification process, and simultaneously, the acid-base modification process is performedThe sexual process also removes part of impurities remained in the catalyst pore channels, thereby leading to the increase of the average pore diameter; however, the preparation process of firstly preparing the unmodified catalyst and then modifying the catalyst with acid and base is adopted, and meanwhile, the acid is citric acid with weak acidity, and the base is Na with weak alkalinity2CO3Therefore, the catalyst prepared by the modification method has less change of various physical and chemical properties than that of the catalyst before modification, and ensures that the catalyst does not have larger change of physical structure while changing the surface acidity, thereby avoiding the defect that the selectivity of ethylene is reduced because the ethylene generated by reaction has polymerization side reaction to generate high-carbon compounds.
Table 2 surface acidity distribution of the molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the modified molecular sieve catalysts prepared in comparative examples 1 to 6
Figure BDA0001833263560000192
Figure BDA0001833263560000201
As can be seen from table 2, the weak acid amount at 70-250 ℃ on the surface of the modified molecular sieve catalyst obtained by acid-base modification in examples 1-6 of the present invention is greatly increased compared to that before modification in comparative examples 1-6, the average increase amplitude is over 55%, the medium strong acid amount at 250-450 ℃ is reduced to a certain extent, the average reduction amplitude is over 29%, and the strong acid amount at more than 450 ℃ of each catalyst before and after modification is not detected, because the reaction for preparing ethylene by ethanol dehydration is a reaction controlled by the catalytic activation of weak acid centers on the surface of the catalyst, the increase of the weak acid amount on the surface of the catalyst is beneficial to the reaction for generating ethylene, so that the conversion rate of raw material ethanol and the selectivity of the product ethylene can be increased, and too strong acid centers can cause the generated ethylene to further undergo side reactions such as polymerization and the like to form high carbon compounds, and further blocking the catalyst pore channel, causing the carbon deposition rate of the catalyst to be increased and the activity stability of the catalyst to be reduced, so that the molecular sieve catalyst prepared by the invention can improve the conversion rate of the raw material ethanol and the selectivity of the product ethylene.
The combined analysis of tables 1 and 2 shows that the HZSM-5 molecular sieve catalyst is sequentially subjected to Na treatment2CO3After the aqueous solution and the citric acid aqueous solution are subjected to two-step alkaline acid modification, the weak acid amount on the surface is greatly improved, the acid amount of medium-strong acid is properly reduced, and the mesoporous volume and the average pore diameter are slightly increased; the activity stability of the catalyst is improved, and the carbon-containing capability of the catalyst is also improved.
(2) The catalytic performances of the modified molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the molecular sieve catalysts prepared in comparative examples 1 to 6 were evaluated, and the specific procedures were as follows: cutting the catalyst into short strips with the length of 1 mm-3 mm, filling 50mL of the catalyst short strips into a stainless steel reaction tube with the size of phi 40 multiplied by 500mm, and introducing N into the stainless steel reaction tube2Heating a stainless steel reaction tube to 120 ℃, keeping the temperature constant for 2 hours to remove physical water in the catalyst, heating to 500 ℃ at the heating rate of 200 ℃/h, keeping the temperature constant for 2 hours to activate the catalyst, and activating N in the activation process2The space velocity is 500h-1(ii) a ② after the activation, the temperature in the stainless steel reaction tube is reduced to 240 ℃ at the cooling rate of 100 ℃/h, and the N is stopped to be led in when the temperature is constant and does not change any more2Starting to introduce 50% ethanol water solution, adjusting output of the ethanol water solution pump to control airspeed of the reaction liquid at 1.5h-1In order to activate stage N2Replacing the whole system, continuously replacing the system within 24h of the initial reaction after the raw material ethanol water solution is introduced, and fully replacing the residual N in the system2Ensuring that the sample obtained by subsequent sampling does not contain N2The error brought to gas analysis is avoided; thirdly, ethanol water solution with the mass concentration of 50 percent is continuously introduced to carry out ethanol dehydration reaction, the temperature in the stainless steel reaction tube is gradually increased and then slowly decreased due to the high surface activity of the catalyst after the ethanol water solution is introduced, and the timing is started after the temperature in the stainless steel reaction tube is decreased to a stable value, and the temperature is stableContinuously keeping the reaction for 10 hours under a certain condition, respectively taking a liquid sample and a gas product after the reaction, respectively analyzing the content of unreacted ethanol in a liquid phase and the purity of ethylene in a gas phase after the reaction, and calculating the conversion rate of the ethanol and the selectivity of the ethylene to obtain the initial activity of the catalyst, wherein the results are shown in the following table 3; fourthly, performing a service life evaluation experiment of the catalyst in a stainless steel reaction tube at the temperature of 240-350 ℃ by adopting a gradual temperature rise method, taking the condition that the ethanol conversion rate and the ethylene selectivity of the catalyst are not less than 95% as activity evaluation indexes, considering that the catalyst is inactivated at the temperature when one index of the two indexes is less than 95%, raising the temperature by 10 ℃ each time after the catalyst is inactivated until the central temperature of a bed layer reaches 350 ℃, stopping the evaluation experiment when the catalyst is inactivated at the temperature, and finishing the performance evaluation experiment; the total time of evaluation in the range of 240-350 ℃ in the stainless steel reaction tube is taken as the service life of the catalyst, in addition, after the temperature of the stainless steel reaction tube is increased each time in the catalyst service life evaluation experiment, the temperature in the catalyst needs a stabilization time of 4-8 h, the ethanol conversion rate and the ethylene selectivity of the catalyst can be rapidly increased in the period to reach the conversion rate and the selectivity index, therefore, the stabilization time is also taken into the effective reaction time, namely the service life, and the results are shown in the following table 4.
Wherein, the calculation formulas of the conversion rate of the ethanol and the selectivity of the ethylene are as follows:
ethanol conversion rate (mass of ethanol reacted)/(mass of ethanol entering reactor)
Ethylene selectivity (mass of ethylene produced)/(mass of ethanol reacted)
Table 3 initial activities of the molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the modified molecular sieve catalysts prepared in comparative examples 1 to 6
Figure BDA0001833263560000221
As can be seen from table 3, the modified molecular sieve catalysts obtained by acid-base modification in examples 1 to 6 of the present invention have equivalent initial ethanol conversion rate and ethylene selectivity to the molecular sieve catalysts prepared in corresponding comparative examples 1 to 6, which shows that although the specific surface area, mesoporous volume, average pore diameter, etc. of the modified catalysts are increased, the modified catalysts have no influence on the ethanol conversion rate and ethylene selectivity of the reaction for preparing ethylene by ethanol dehydration, and no significant side reaction of ethylene polymerization to generate high-carbon compounds occurs.
TABLE 4 service lives of the molecular sieve catalysts prepared in examples 1 to 6 of the present invention and the modified molecular sieve catalysts prepared in comparative examples 1 to 6
Figure BDA0001833263560000231
The average carbon deposition rate of the catalyst in table 4 means the mass percentage of carbon deposition generated on the surface of each catalyst per unit time in the catalyst.
As can be seen from table 4, the service life of the modified molecular sieve catalysts obtained through acid-base modification in examples 1 to 6 of the present invention is greatly prolonged, and the prolonged time is over 215 hours, compared with the service life of the molecular sieve catalysts prepared through corresponding comparative examples 1 to 6, the average carbon deposition rate of the modified molecular sieve catalysts obtained through acid-base modification in examples 1 to 6 is reduced by more than 1 time, which indicates that the service life of the acid-base modified molecular sieve catalysts is prolonged, the carbon capacity is increased, the carbon deposition rate is reduced, and the activity stability is better.
The use of the modified molecular sieve catalyst of the present invention in the catalytic dehydration of ethanol to ethylene is described in detail in examples 7 to 9.
Example 7
The application of the modified molecular sieve catalyst in the preparation of ethylene by catalyzing ethanol dehydration comprises the following steps:
step one, filling 40.0g of the modified molecular sieve catalyst prepared in the example 1 into a fixed bed reactor, then introducing nitrogen into the fixed bed reactor, raising the temperature of the fixed bed reactor to 500 ℃ within 2 hours, and activating the modified molecular sieve catalyst for 2 hours after the temperature is stabilized;
step two, introducing an ethanol water solution into the fixed bed reactor to carry out ethanol dehydration reaction to obtain ethylene; the mass concentration of the ethanol aqueous solution is 50 percent, and the airspeed of the ethanol aqueous solution is 1.5h-1The introducing pressure of the ethanol water solution is 0.25 MPa; the temperature of the ethanol dehydration reaction is 240-350 ℃, and when any numerical value of the ethanol conversion rate and the ethylene selectivity of the modified molecular sieve catalyst is less than 95% in the ethanol dehydration reaction process, the temperature of the ethanol dehydration reaction is increased by 10 ℃ to improve the activity of the modified molecular sieve catalyst to continue the ethanol dehydration reaction.
Example 8
The invention differs from example 7 in that the modified molecular sieve catalyst employed was prepared from example 5.
Example 9
The invention differs from example 7 in that the modified molecular sieve catalyst employed was prepared from example 6.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (7)

1. A modified molecular sieve catalyst for preparing ethylene by ethanol dehydration is characterized by being prepared by the following method:
step one, uniformly mixing HZSM-5 molecular sieve powder, macroporous pseudo-boehmite powder and sesbania powder to obtain a mixture, adding a sodium carboxymethylcellulose aqueous solution into the mixture, uniformly mixing, rolling, sequentially extruding and drying, and naturally cooling to obtain an unmodified strip molecular sieve catalyst; the average particle size of the HZSM-5 molecular sieve powder is 0.5 mu m, the molar ratio of silicon to aluminum is 50-60, and the specific surface area is not less than 200m2Na/g, pore volume not less than 0.15mL/g2Mass of OThe percentage content is not more than 0.1%; the specific surface area of the macroporous pseudo-boehmite powder is not less than 250m2Na/g, pore volume of not less than 1.0mL/g2O is not more than 0.05 percent by mass, and Al2O3The mass percentage content of the compound is 70 percent; the sesbania powder in the unmodified strip molecular sieve catalyst accounts for 3.0 percent by mass; the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 0.5%, the adding volume of the sodium carboxymethyl cellulose aqueous solution is 34.5-36.5% of the mass of the mixture, the unit of the volume is mL, and the unit of the mass is g;
step two, adding the unmodified strip molecular sieve catalyst obtained in the step one into Na2CO3Heating the aqueous solution to perform alkali modification, taking out and drying to obtain an alkali-modified strip molecular sieve catalyst; the temperature of the alkali modification is 50-70 ℃, and the time is 2-4 h;
step three, adding the alkali-modified strip-shaped molecular sieve catalyst obtained in the step two into a citric acid aqueous solution for acid modification, taking out and drying to obtain an acid-modified strip-shaped molecular sieve catalyst, and roasting the acid-modified strip-shaped molecular sieve catalyst to obtain a modified molecular sieve catalyst; the temperature of the acid modification is 50-70 ℃, and the time is 2-4 h; the modified molecular sieve catalyst comprises 60-80% of HZSM-5 molecular sieve powder and Al in percentage by mass2O3The mass percentage of the component (A) is 20-40%.
2. The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration according to claim 1, wherein in the second step, the unmodified bar-shaped molecular sieve catalyst and Na are used in the alkali modification process2CO3The mass ratio of the aqueous solution is 1: (20 to 30) said Na2CO3Preparation of aqueous solution raw Material Na2CO3For analytical reagent.
3. The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration according to claim 1, wherein the mass ratio of the bar molecular sieve catalyst after alkali modification to the aqueous solution of citric acid in the acid modification process in step three is 1: (20-30), the preparation raw material of the citric acid aqueous solution is citric acid monohydrate, and the citric acid monohydrate is an analytical reagent.
4. The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration according to claim 1, wherein the drying temperature in the first step and the drying temperature in the second step and the drying time in the third step are both 100 ℃ to 120 ℃ and the time is both 2h to 4 h.
5. The modified molecular sieve catalyst for preparing ethylene by ethanol dehydration according to claim 1, wherein the roasting treatment in step three is carried out by the following steps: heating to 250 ℃ at a heating rate of 100 ℃/h in an air atmosphere, keeping the temperature for 1h, then continuously heating to 350 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1h, and finally heating to 500 ℃ at a heating rate of 100 ℃/h, keeping the temperature for 1 h.
6. The application of the modified molecular sieve catalyst for preparing ethylene by ethanol dehydration as claimed in any one of claims 1 to 5 is characterized by comprising the following steps:
filling a modified molecular sieve catalyst into a fixed bed reactor, introducing nitrogen into the fixed bed reactor, and heating for activation;
and step two, introducing an ethanol water solution into the fixed bed reactor to carry out ethanol dehydration reaction to obtain ethylene.
7. The use of claim 6, wherein the mass concentration of the ethanol aqueous solution in the second step is 50%, and the space velocity of the ethanol aqueous solution is 1.5h-1The introducing pressure of the ethanol water solution is 0.25MPa, and the temperature of the ethanol dehydration reaction is 240-350 ℃.
CN201811214739.7A 2018-10-18 2018-10-18 Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof Active CN109174169B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811214739.7A CN109174169B (en) 2018-10-18 2018-10-18 Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811214739.7A CN109174169B (en) 2018-10-18 2018-10-18 Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof

Publications (2)

Publication Number Publication Date
CN109174169A CN109174169A (en) 2019-01-11
CN109174169B true CN109174169B (en) 2021-06-22

Family

ID=64945892

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811214739.7A Active CN109174169B (en) 2018-10-18 2018-10-18 Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof

Country Status (1)

Country Link
CN (1) CN109174169B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112657535B (en) * 2019-10-16 2023-01-24 中国石油化工股份有限公司 Olefin removal catalyst, and preparation method and application thereof
CN110981718B (en) * 2019-12-04 2022-08-05 万华化学集团股份有限公司 Method for preparing 3-hydroxypropionic acid by continuous hydration of acrylic acid

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101565346A (en) * 2008-04-24 2009-10-28 中国石油化工股份有限公司 Method for preparing ethylene by ethanol dehydration
CN103372456A (en) * 2012-04-13 2013-10-30 上海中科高等研究院 Molecular sieve based catalyst and preparation and application thereof
CN103506150A (en) * 2013-10-18 2014-01-15 中国科学院上海高等研究院 Water vapor modified catalyst for preparing gasoline from methanol, and preparation method and application of water vapor modified catalyst
CN106540736A (en) * 2016-10-14 2017-03-29 太原理工大学 A kind of hierarchical pore molecular sieve catalyst of Ethanol Dehydration ethylene and its preparation method and application
CN107282088A (en) * 2016-04-01 2017-10-24 神华集团有限责任公司 The method of organic oxygen-containing compound olefin hydrocarbon molecules sieve catalyst and preparation method thereof and organic oxygen-containing compound alkene

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10626019B2 (en) * 2014-12-30 2020-04-21 W. R. Grace & Co.-Conn. Methods for preparing zeolites with surfactant-templated mesoporosity and tunable aluminum content

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101565346A (en) * 2008-04-24 2009-10-28 中国石油化工股份有限公司 Method for preparing ethylene by ethanol dehydration
CN103372456A (en) * 2012-04-13 2013-10-30 上海中科高等研究院 Molecular sieve based catalyst and preparation and application thereof
CN103506150A (en) * 2013-10-18 2014-01-15 中国科学院上海高等研究院 Water vapor modified catalyst for preparing gasoline from methanol, and preparation method and application of water vapor modified catalyst
CN107282088A (en) * 2016-04-01 2017-10-24 神华集团有限责任公司 The method of organic oxygen-containing compound olefin hydrocarbon molecules sieve catalyst and preparation method thereof and organic oxygen-containing compound alkene
CN106540736A (en) * 2016-10-14 2017-03-29 太原理工大学 A kind of hierarchical pore molecular sieve catalyst of Ethanol Dehydration ethylene and its preparation method and application

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
酸碱改性HZSM-5分子筛上甲醇制取均四甲苯的研究;肖何等;《燃料化学学报》;20130131;第102-109页 *
高硅HZSM-5 分子筛的有机酸改性及其在甲醇制丙烯中的应用;陈小迪等;《石油化工》;20180515;第408-414页 *

Also Published As

Publication number Publication date
CN109174169A (en) 2019-01-11

Similar Documents

Publication Publication Date Title
RU2607633C2 (en) Moulded catalyst for converting methanol into aromatic hydrocarbons and method of producing said catalyst
JP5698142B2 (en) Method of purifying alcohol in the presence of acid catalyst before use
US11066343B2 (en) Method for producing p-xylene
CN109174169B (en) Modified molecular sieve catalyst for preparing ethylene by ethanol dehydration and application thereof
CN108529642A (en) A kind of preparation method of Cu-SSZ-13 molecular sieves
US11434183B2 (en) Catalyst for preparing ethylbenzene from ethanol and benzene, preparation therefor and use thereof
CN1067603C (en) Metal modified small-porosity P-Si-Al molecular sieve catalyst, its preparing process and use thereof
EA007767B1 (en) Production of olefins
CN111167509A (en) Carbon tetraolefin cracking catalyst, preparation method thereof and catalytic cracking method
CN105983435A (en) Butane isomerization catalyst and preparation method and application thereof
CN112495425A (en) Method for preparing p-coumaric acid ester by catalyzing lignin depolymerization through molybdenum oxide loaded by hierarchical pore molecular sieve
CN107790173B (en) Catalyst for preparing dimethyl sulfide and method for synthesizing dimethyl sulfide
CN107971008B (en) Catalytic cracking catalyst, preparation method thereof and petroleum hydrocarbon catalytic cracking method
CN103028435A (en) Catalyst for preparing propylene through conversion of methanol and preparation method of catalyst
CN102039150A (en) Preparation method of binderless Y zeolite catalyst
CN108033462B (en) Hierarchical porous LTL molecular sieve and synthesis method and application thereof
CN102039156B (en) Preparation method of binder-free beta zeolite catalyst
CN111253204B (en) Method for preparing ethylene by ethanol dehydration
CN107971007B (en) Catalytic cracking catalyst, preparation method thereof and petroleum hydrocarbon catalytic cracking method
CN111295243B (en) Catalyst for producing olefin by dehydrogenation of alkane and method for producing olefin using the same
CN107971005B (en) Catalytic cracking catalyst, preparation method thereof and petroleum hydrocarbon catalytic cracking method
CN107973305B (en) Mesoporous-rich IMF structure molecular sieve and preparation method thereof
Gui et al. Quasi-solid state synthesis of EU-1 zeolite and its catalytic properties for the isomerization of C 8 aromatics
US20110034750A1 (en) Process for the production of light olefins from ethanol in the presence of a macroporous catalyst that comes in the form of balls
CN114433076B (en) Supported hydrogenolysis catalyst and preparation method and application thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant