WO2020047902A1

WO2020047902A1 - Preparation method and use of molecular sieve catalyst

Info

Publication number: WO2020047902A1
Application number: PCT/CN2018/106165
Authority: WO
Inventors: 苏雄; 杨晓丽; 黄延强; 张涛
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2018-09-07
Filing date: 2018-09-18
Publication date: 2020-03-12
Also published as: CN110882715B; CN110882715A

Abstract

Disclosed is a method for preparing a molecular sieve catalyst. The method comprises: obtaining a ZSM-5 seed crystal gel solution; adding mixture I containing a silicon source, an aluminum source, an alkali and water to the ZSM-5 seed crystal gel solution to obtain a mixture, and aging same to obtain a solid gel; under a sealed condition, subjecting the solid gel to water steam-assisted crystallization, calcining same, carrying out ammonium ion exchange, and calcining same to obtain a nano-sized ZSM-5 molecular sieve; and subjecting the obtained nano-sized ZSM-5 molecular sieve to a water steam treatment and a phosphorus modification, and calcining same to obtain the molecular sieve catalyst. The catalyst has the characteristics of a uniform distribution of acidic sites and a high crystallinity, and the preparation process therefor produces less waste water, which is convenient for a scale-up production. The catalyst has a good hydrothermal stability during an alkylation reaction between ethanol and benzene, can maintain a high ethyl selectivity under the condition of a lower benzene-to-ethanol ratio; furthermore, there is a low content of xylene impurity in the product. Same has good industrial application prospects.

Description

Preparation method and application of molecular sieve catalyst

Technical field

The present application relates to a preparation method and application of a molecular sieve catalyst, and belongs to the field of materials.

Background technique

Ethylbenzene is an important commercial derivative of benzene in the current chemical industry. It is mainly used for dehydrogenation to styrene, and it is also an important raw material for the production of polystyrene and ABS resin. In recent years, the market demand for ethylbenzene has shown a clear upward trend. However, the depletion of petroleum resources and the soaring oil prices have greatly increased the cost of ethylene alkylation. It has become a trend to seek new raw materials instead of ethylene to produce ethylbenzene. As a renewable and clean energy, ethanol can be produced not only through the petroleum route, but also from large-scale production of agricultural and sideline products and coal, which saves costs from the source of ethanol production and also provides more space for the choice of raw materials for ethylbenzene production. Gas-phase alkylation of ethanol and benzene to ethylbenzene is based on low-cost renewable resources ethanol or coal-based ethanol. The process is environmentally friendly. It not only optimizes the product structure of the chemical market, increases economic benefits, but also contributes to the national energy strategy. Deployment has long-term implications.

The ethanol to ethylbenzene process is a process in which ethanol and benzene undergo ethanol dehydration and benzene alkylation simultaneously in the reactor. The catalyst used not only needs to meet the high dehydration selectivity and conversion of ethanol, but also has certain requirements for the catalytic efficiency of the alkylation of ethylene and benzene. ZSM-5 molecular sieve has strong acidic sites and can effectively catalyze ethanol dehydration and benzene alkylation at the same time; and the large-scale preparation process of the molecular sieve is relatively mature and has become the main catalyst in the reaction industry.

However, due to the narrow pores of the ZSM-5 molecular sieve, the mass transfer of reactants and products is limited; at the same time, the acidity of ZSM-5 is relatively strong, and the cracking reaction of ethylbenzene and polyalkylbenzene will occur, leading to the selectivity of ethylbenzene Decreased, the content of impurities such as toluene, xylene increased. In response to these problems, scholars at home and abroad have proposed many solutions, roughly as follows. First, the molecular sieve is expanded to increase its mass transfer efficiency. Li Jianjun of Xiamen University uses NaOH solution to ream the ZSM-5 molecular sieve, which improves the stability of the molecular sieve and the selectivity of ethylbenzene (Journal of Xiamen University (Natural Edition), 2012, 51, 5, 882-887); Wen Ding et al. The addition of Mg auxiliaries after treating ZSM-5 with alkali significantly increased the selectivity of ethylbenzene compared to the original parent molecular sieves (RSC Advances, 2014, 4, 50123-50129). Secondly, adding auxiliaries to the molecular sieve to adjust its acidic characteristics, thereby reducing side reactions, which is also the most commonly used method. Zhengzhou University of Light Industry Wei Huirong reported that a catalyst made of phosphate-magnesium composite modified ZSM-5 molecular sieves and Al ₂ O ₃ was used for the gas phase alkylation of ethanol to ethylbenzene. The molar ratio of benzene to ethanol was 340-400 ℃. The mass space velocity is 3.5-4.5h ^-1 , the molar conversion of benzene is 20%, the molar selectivity of ethylbenzene is 90%, and the active period is 630h (Journal of Zhengzhou University (Engineering Science Edition), 1992, 2, 60-65). Iron and titanium modified ZSM-5 was synthesized by Shanghai Baosteel Chemical Co., Ltd. and Shanxi Coal Chemistry Research Institute by impregnation method or ion-exchange method. It was formed by adding a binder and dilute nitric acid when the molar ratio of benzene to ethanol was 4. , Ethylbenzene selectivity is greater than 92% (Progress in Chemical Industry, 2008, 27, 1800-1804; CN101537269A). Shanghai Wuzheng Engineering Technology Co., Ltd. has developed a high Si / Al ZSM-5, adding a binder and IIA, IIIA, VA group elements or rare earth metals, such as Mg, B, P, La as additives, with high selectivity. Ethylbenzene (CN101450888A). Jiao Feng of Beijing University of Chemical Technology prepared boron-modified ZSM-5 molecular sieve by ion exchange method, and investigated the catalytic performance and desulfurization performance of alkylation of coking benzene and ethanol on a continuous fixed-bed reactor. The results of the reaction evaluation show that the selectivity of ethylbenzene is slightly reduced and the conversion of benzene is increased after the modification (Industrial Catalysis, 2009, 17, 58-61). However, none of these patents has publicly reported the preparation of nano-ZSM-5.

Summary of the Invention

According to one aspect of the present application, a method for preparing a molecular sieve catalyst is provided. The method has good reproducibility, generates less waste water, and can be used for large-scale production. The prepared molecular sieve catalyst has a relatively low reaction ratio of benzene to alcohol. High selectivity of ethyl group, low content of xylene impurities, and high hydrothermal stability.

The catalyst involved in this application has the characteristics of uniform acid site distribution, high crystallinity, and less waste water produced by the preparation process, which is convenient for scale-up production; the catalyst has good hydrothermal stability in the alkylation reaction between ethanol and benzene, and has lower benzene alcohol. Compared with the feed conditions, it can still maintain high ethyl selectivity, and the xylene impurity content in the product is low, which has a good industrial application prospect.

The molecular sieve catalyst described in this application is a small-grain ZSM-5 molecular sieve with high silicon content. The silicon-aluminum molar ratio SiO ₂ / Al ₂ O ₃ of the ZSM-5 molecular sieve is 80 to 140, and the crystal grain diameter of the molecular sieve is 50 to 300 nm.

The method for preparing a molecular sieve catalyst is characterized in that it includes:

(1) obtaining a ZSM-5 seed gel solution;

(2) adding the mixture I containing a silicon source, an aluminum source, an alkali and water to the ZSM-5 seed gel solution described in step (1) to obtain a mixture II, and aging to obtain a solid gel;

(3) Under a sealed condition, the solid gel water-vapor-assisted crystallization described in step (2), roasting I, ammonium ion exchange, roasting II to obtain nano ZSM-5 molecular sieve;

(4) The nano-ZSM-5 molecular sieve obtained in step (3) is subjected to steam treatment and phosphorus modification, and calcined III to obtain the molecular sieve catalyst.

Optionally, the method for obtaining the ZSM-5 seed gel solution in step (1) includes: stirring the solution containing a silicon source and a templating agent, and then refluxing to obtain the ZSM-5 seed gel solution.

Optionally, the molar ratio of the silicon source and the templating agent is 0.5 to 5: 1;

The stirring conditions are: stirring at 25-40 ° C in a water bath for 0.5-24 hours;

The conditions for the reflux are: in an oil bath at 80 to 160 ° C., the reflux treatment is performed for 24 to 120 hours.

Optionally, the upper limit of the molar ratio of the silicon source and the template is selected from 0.8: 1, 1: 1, 1.2: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1, 3.5: 1, 4 : 1, 4.5: 1, 4.8: 1 or 5: 1; the lower limit is selected from 0.5: 1, 0.8: 1, 1: 1, 1.2: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1, 3.5: 1, 4: 1, 4.5: 1 or 4.8: 1.

When a person skilled in the art implements the technical solution described in this application, he can select a specific molar ratio within a range of 0.5 to 5: 1 according to the actual needs of the silicon source and the template; The technical solution described in this application can be realized and the technical effect can be obtained.

Optionally, the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate;

The template agent is selected from at least one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetraethylammonium bromide, tetraethylammonium hydroxide, and tetrapropylammonium chloride.

Optionally, the molar ratio of silicon source, aluminum source, alkali and water in the mixture I in step (2) satisfies:

SiO ₂ : Al ₂ O ₃ : M ₂ O: H ₂ O = 10 ～ 300: 1: 0.1 ～ 20: 10 ～ 200;

Among them, water is calculated in the number of moles of H ₂ O itself, silicon source is calculated in the number of moles of SiO ₂ , aluminum source is calculated in the number of moles of Al ₂ O ₃ , and alkali is calculated in the number of moles of alkali metal oxide; where M is alkali metal;

The ZSM-5 seed gel solution is 5% to 50% of the total mass of the mixture II.

Optionally, the upper limit of the molar ratio (SiO ₂ / Al ₂ O ₃ ) of the silicon source to the aluminum source in the mixture I is selected from 20, 30, 40, 50, 60, 80, 100, 120, 150, 180, ₂₀₀ , 230, 250, 280, or 300; the lower limit is selected from 10, 20, 30, 40, 50, 60, 80, 100, 120, 150, 180, 200, 230, 250, or 280.

Optionally, the upper limit of the molar ratio (M ₂ O / Al ₂ O ₃ ) of the base to the aluminum source in the mixture I is selected from 0.2, 0.5, 0.8, 1.0, 1.5, 1.8, _{2.0, 2.5,} _{3, 5} , 8 , 10, 12, 15, 18, or 20; the lower limit is selected from 0.1, 0.2, 0.5, 0.8, 1.0, 1.5, 1.8, 2.0, 2.5, 3, 5, 8, 10, 12, 15, or 18.

Optionally, the upper limit of the molar ratio (H ₂ O / Al ₂ O ₃ ) of water to the aluminum source in the mixture I is selected from 15, 20, 30, 50, 60, 80, 100, 120, 150, 180, or 200 ; The lower limit is selected from 10, 15, 20, 30, 50, 60, 80, 100, 120, 150, or 180.

Optionally, the upper limit of the proportion of the ZSM-5 seed gel solution to the total mass of the mixture II is selected from 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45 % Or 50%; the lower limit is selected from 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%.

Optionally, the silicon source in step (2) is selected from at least one of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate. That is, the silicon source is any one or more mixed silicon sources of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate.

Optionally, the aluminum source is selected from at least one of sodium metaaluminate, aluminum powder, aluminum nitrate, and aluminum hydroxide. That is, the aluminum source is any one or more mixed aluminum sources of sodium metaaluminate, aluminum powder, aluminum nitrate, and aluminum hydroxide.

Optionally, the base is selected from at least one of sodium hydroxide and potassium hydroxide. That is, the base is one or a mixture of sodium hydroxide and potassium hydroxide.

Optionally, the aging conditions described in step (2) are: stirring at room temperature for 6 to 36 hours, and then stirring in a water bath at 40 to 70 ° C.

Optionally, the aging conditions described in step (2) are: stirring at room temperature for 12 to 36 hours, and then stirring in a water bath at 40 to 70 ° C.

Optionally, the conditions for the steam-assisted crystallization described in step (3) are: crystallization at 120 to 180 ° C. for 10 to 60 hours.

Optionally, the upper limit of the crystallization temperature is selected from 130 ° C, 140 ° C, 150 ° C, 160 ° C, 170 ° C, or 180 ° C; and the lower limit is selected from 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, or 170 ° C. ℃.

Optionally, the upper limit of the crystallization time is selected from 15h, 18h, 20h, 24h, 25h, 30h, 35h, 38h, 40h, 45h, 48h, 50h, 55h or 60h; the lower limit is selected from 10h, 15h, 18h, 20h, 24h, 25h, 30h, 35h, 38h, 40h, 45h, 48h, 50h or 55h.

Optionally, the conditions for firing I in step (3) are: firing at 300 to 600 ° C for 1 to 10 hours;

The conditions for the roasting II are: roasting at 400 to 600 ° C for 1 to 3 hours.

Optionally, the conditions for the roasting II are: roasting at 500 ° C for 2h.

Optionally, the upper limit of the temperature of the roasting I is 350 ° C, 400 ° C, 450 ° C, 500 ° C, 550 ° C, or 600 ° C; the lower limit is selected from 300 ° C, 350 ° C, 400 ° C, 450 ° C, 500 ° C, or 550 ° C .

Optionally, the upper temperature limit of the roasting I is 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h; the lower limit is selected from 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, or 9h .

Optionally, the heating rate of the roasting I is 8 to 12 ° C / min.

Optionally, the heating rate of the roasting I is 10 ° C / min.

Optionally, the conditions for the steam treatment in step (4) are: the pressure is normal pressure, the temperature is 300-700 ° C, and the time is 0.5-10 hours.

Optionally, the upper limit of the temperature of the water vapor treatment is selected from 350 ° C, 400 ° C, 450 ° C, 500 ° C, 550 ° C, 600 ° C, 650 ° C, or 700 ° C; the lower limit is selected from 300 ° C, 350 ° C, 400 ° C, 450 ° C, 500 ° C, 550 ° C, 600 ° C or 650 ° C.

Optionally, the upper limit of the water vapor treatment time is selected from 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h , 8.5h, 9h, 9.5h or 10h.

Optionally, the water vapor treatment includes: passing nitrogen through a water holding device and carrying water vapor through a molecular sieve bed, wherein a flow rate of the nitrogen is 2 to 50 ml / min.

Specifically, the method used for the water vapor treatment is that nitrogen gas passes through the water holding device and carries water vapor through the molecular sieve bed, wherein the flow rate of the nitrogen gas is 2 to 50 ml / min.

Optionally, the conditions for the phosphorus modification in step (4) are: placing the sample to be treated in a phosphorus-containing solution, and stirring;

The mass ratio of the phosphorus-containing solution to the sample to be processed is 1-50.

Optionally, the weight ratio of the phosphorus-containing solution and the ZSM-5 molecular sieve is 1-50.

Optionally, the upper limit of the mass ratio of the phosphorus-containing solution to the sample to be processed is selected from 2, 5, 8, 10, 15, 20, 25, 30, 35, 40, 45, or 50; the lower limit is selected from 1, 2, 5, 8, 10, 15, 20, 25, 30, 35, 40, or 45.

Optionally, the concentration of the phosphorus-containing solution is 0.02 to 10 mol / L;

The stirring conditions are: stirring in a water bath at 20 to 90 ° C for 0.5 to 15 hours, and the stirring speed is 50 to 400 rpm.

When a person skilled in the art implements the technical solution described in this application, he can select a specific stirring speed in the range of 50 to 400 rpm according to actual needs; within the above range, the present application can be implemented in this application. The technical solution obtains the technical effect.

Optionally, the upper limit of the concentration of the phosphorus-containing solution is selected from 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L L, 4mol / L, 4.5mol / L, 5mol / L, 5.5mol / L, 6mol / L, 6.5mol / L, 7mol / L, 7.5mol / L, 8mol / L, 8.5mol / L, 9mol / L , 9.5mol / L or 10mol / L; the lower limit is selected from 0.05mol / L, 0.1mol / L, 0.5mol / L, 1mol / L, 1.5mol / L, 2mol / L, 2.5mol / L, 3mol / L, 3.5mol / L, 4mol / L, 4.5mol / L, 5mol / L, 5.5mol / L, 6mol / L, 6.5mol / L, 7mol / L, 7.5mol / L, 8mol / L, 8.5mol / L, 9mol / L or 9.5mol / L.

Optionally, the phosphorus source of the phosphorus-containing solution includes at least one of phosphoric acid, diammonium phosphate, diammonium hydrogen phosphate, and ammonium phosphate;

The concentration of the phosphorus-containing solution is 0.1 to 5 mol / L.

Optionally, the concentration of the phosphoric acid is 85% by weight.

Optionally, the conditions for roasting III in step (4) are: roasting at 200 to 700 ° C for 1 to 10 hours.

Optionally, the upper temperature limit of the roasting III is selected from 250 ° C, 300 ° C, 350 ° C, 400 ° C, 450 ° C, 500 ° C, 550 ° C, 600 ° C, 650 ° C, or 700 ° C; and the lower limit is selected from 200 ° C, 250 ° C, 300 ° C, 350 ° C, 400 ° C, 450 ° C, 500 ° C, 550 ° C, 600 ° C or 650 ° C.

Optionally, the upper time limit of the roasting III is selected from 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h , 9h, 9.5h or 10h.

Optionally, the molecular sieve catalyst is a small-grain ZSM-5 molecular sieve with a high silicon content.

Optionally, the molecular sieve catalyst is a small-grain ZSM-5 molecular sieve with a grain diameter of 20 to 500 nm;

Optionally, the molecular sieve catalyst has a crystal grain diameter of 50-300 nm.

Optionally, the molecular sieve catalyst has a silicon-aluminum molar ratio SiO ₂ / Al ₂ O ₃ of 50-200.

Optionally, the molecular sieve catalyst has a silicon-aluminum molar ratio SiO ₂ / Al ₂ O ₃ of 80-140.

Optionally, the upper limit of the silicon-aluminum molar ratio SiO ₂ / Al ₂ O _{3 of} the molecular sieve catalyst is selected from 60, 70, 80, 82, 84, 90, 92, 96, 100, 107, 110, 112, 113, 120 , 124, 130, 132, 136, 140, 150, 160, 170, 180, 190 or 200.

Optionally, the method for preparing the molecular sieve catalyst includes:

1) Seed Synthesis

The silicon source was weighed and dissolved in deionized water, and a template agent was added, and the mixture was stirred in a water bath at 25 to 40 ° C for 0.5 to 24 hours; then transferred to an oil bath at 80 to 160 ° C and subjected to reflux treatment for 24 to 120 hours to obtain a seed gel solution. ;

2) Preparation of xerogel

The silicon source, aluminum source, alkali, and water were weighed according to the ratio and stirred to obtain a mixture. The molar ratios of the materials in the mixture were SiO ₂ , Al ₂ O ₃ , M ₂ O, and H ₂ O, respectively. SiO ₂ : Al ₂ O ₃ : M ₂ O: H ₂ O = 10 ～ 300: 1: 0.1 ～ 20: 10 ～ 200, where M is an alkali metal; add the above mixture to the seed gel solution, and stir at room temperature for 12 ～ 36h , Placed in a water bath at 40 to 70 ° C and stirred to evaporate water in the solution to obtain a solid gel;

3) Synthesis of ZSM-5 molecular sieve

The solid gel is ground into a powder and placed on a bracket; the whole is placed in a hydrothermal kettle containing 1-10 ml of water and sealed; placed at 120-180 ° C for crystallization and kept at a constant temperature for 10-60 hours; The product was filtered and washed until the washing solution became neutral, filtered, and dried at 60 to 120 ° C; then the sample was baked at 300 to 600 ° C for 1 to 10 hours; then, ammonium exchange and roasted to obtain ZSM-5 molecular sieve;

Wherein, the conditions for the ammonium ion exchange are: 3 times exchange with a 1 mol / L ammonium nitrate solution in a 70 ° C water bath condition;

4) Post-treatment of ZSM-5 molecular sieve

The sample obtained in 3) is subjected to steam treatment, wherein the processing conditions are normal pressure, the temperature is 300-700 ° C, and the time is 0.5-10 hours; the treated sample is placed in a phosphorus-containing solution in a water bath, and the phosphorus-containing solution is stirred. The concentration is 0.02 to 10 mol / L, the water bath temperature is 20 to 90 ° C, the stirring speed is 50 to 400 rpm, and the time is 0.5 to 15 hours; the treated sample is filtered and washed until the washing solution becomes neutral, and filtered, Drying treatment is performed at 60 to 120 ° C; the sample is then baked at 200 to 700 ° C for 1 to 10 hours to obtain the molecular sieve catalyst.

As one of the specific embodiments, the method for preparing the molecular sieve catalyst includes:

1.Synthesis of seed

The silicon source was weighed and dissolved in deionized water, and a template agent was added, and the mixture was stirred in a water bath at 25 to 40 ° C for 0.5 to 24 hours; then transferred to an oil bath at 80 to 160 ° C and subjected to reflux treatment for 24 to 120 hours to obtain a seed gel solution. .

2. Preparation of xerogel

According to a certain proportion were weighed silicon source, an aluminum source, an alkali, water was stirred uniformly to obtain a mixture, the mixture of each material respectively _{_{_{SiO 2, Al 2 O 3,}}} M 2 O, molar ratio of H ₂ O gauge was SiO _2: Al ₂ O ₃ : M ₂ O: H ₂ O = 10 ～ 300: 1: 0.1 ～ 20: 10 ～ 200, where M is an alkali metal; the above mixture is added to the seed gel solution and stirred at room temperature for 12 For ~ 36h, place in a water bath at 40 ~ 70 ° C and stir to evaporate the water in the solution to obtain a solid gel.

3. Synthesis of ZSM-5 molecular sieve

The solid gel is ground into a powder and placed on a polytetrafluoroethylene bracket; the whole is placed in a hydrothermal kettle containing 1-10 ml of water and sealed; placed in an oven at 120-180 ° C for crystallization and kept at a constant temperature 10 ～ 60h; filtering and washing the obtained product until the washing liquid becomes neutral, and the filtered cake is transferred to an oven at 60 ～ 120 ℃ for drying treatment; then the sample is roasted in a muffle furnace at 300 ～ 600 ℃ 1 ~ 10h; the catalyst is exchanged 3 times with ammonium nitrate solution (1mol / L, 70 ° C water bath), and calcined to obtain ZSM-5 molecular sieve.

4. Post-treatment of ZSM-5 molecular sieve

The sample obtained in step 3 is placed in a tube furnace for water vapor treatment, where the treatment conditions are normal pressure, the temperature is 300-700 ° C, and the time is 0.5-10 hours. Place the treated sample in a flask, add a phosphorus-containing solution, and transfer to a water bath for further processing. The concentration of the phosphorus-containing solution is 0.02 to 10 mol / L, the water bath temperature is 20 to 90 ° C, and the stirring speed is 50 to 400 rpm. Minutes and time is 0.5 ~ 15h. The processed sample is filtered and washed until the washing liquid becomes neutral, and the filtered cake is transferred to an oven at 60-120 ° C for drying treatment; then the sample is baked in a 200-700 ° C muffle furnace for 1-10 hours That is, a catalyst for gas-phase alkylation of ethanol and benzene to prepare ethylbenzene is obtained.

In step 1, the silicon source is any one or more mixed silicon sources of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate; template agents are tetrapropylammonium hydroxide and tetrapropylammonium bromide. Or any mixture of tetraethylammonium bromide, tetraethylammonium hydroxide, and tetrapropylammonium chloride.

The silicon source in step 2 is any one or more mixed silicon sources of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate; the aluminum source is sodium metaaluminate, aluminum powder, aluminum nitrate, and hydrogen Any one or more mixed aluminum sources in alumina; the base is any one or two mixtures of sodium hydroxide and potassium hydroxide.

The weight ratio of the seed gel solution added in step 2 to the mixture is 5% to 50%.

The method used for the high-temperature water vapor treatment in step 4 is that nitrogen passes through the H ₂ O-containing device and carries water vapor through the molecular sieve bed. The flow rate of nitrogen is 2-50 ml / min.

The phosphorus source used in step 4 is any one or two mixed phosphorous sources of 85% strength phosphoric acid, monoammonium phosphate, diammonium hydrogen phosphate, and ammonium phosphate; the concentration of the phosphorus-containing solution used is 0.1 to 5 mol / L. ; The weight ratio of the phosphorus-containing solution and the ZSM-5 molecular sieve is 1 to 50.

In another aspect of the present application, a catalyst for preparing ethylbenzene by gas-phase alkylation of ethanol and benzene is provided, which comprises at least one of a molecular sieve catalyst prepared according to any one of the methods described above.

In another aspect of the present application, a method for preparing ethylbenzene by gas-phase alkylation of ethanol and benzene is provided, which comprises: passing a raw material containing ethanol and benzene through a fixed-bed reactor containing a catalyst and reacting to obtain ethyl benzene;

Wherein, the catalyst is selected from at least one of molecular sieve catalysts prepared according to any one of the methods described above.

Optionally, the conditions for the reaction are:

The molar ratio of benzene to ethanol is 4 to 6: 1; the mass space velocity of ethanol is 0.5 to 2.5 h ^-1 , the reaction pressure is 0.5 to 2.5 MPa, and the reaction temperature is 300 to 500 ° C.

Optionally, the upper limit of the molar ratio of benzene to ethanol is selected from 4.5: 1, 4.8: 1, 5: 1, 5.2: 1, 5.5: 1, 5.8: 1, or 6: 1; and the lower limit is selected from 4: 1. 4.5: 1, 4.8: 1, 5: 1, 5.2: 1, 5.5: 1, or 5.8: 1.

Optionally, the upper limit of the mass space velocity of the ethanol is selected from 0.8h ^-1 , 1.0h ^-1 , 1.2h ^-1 , 1.5h ^-1 , 1.8h ^-1 , 2.0h ^-1 or 2.5h ^-1 ; It is selected from 0.5h ^-1 , 0.8h ^-1 , 1.0h ^-1 , 1.2h ^-1 , 1.5h ^-1 , 1.8h ^-1 or 2.0h ^-1 .

Optionally, the upper limit of the reaction pressure is selected from 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2.0 MPa, or 2.5 MPa; the lower limit is selected from 0.5 MPa, 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.5 MPa, 1.8MPa or 2.0MPa.

Optionally, the upper limit of the reaction temperature is selected from 320 ° C, 350 ° C, 380 ° C, 400 ° C, 450 ° C, 480 ° C, or 500 ° C; the lower limit is selected from 300 ° C, 320 ° C, 350 ° C, 380 ° C, 400 ° C, 450 ° C or 480 ° C.

The present application adopts a method of combining seed crystals with a solid phase crystallization method in a gel solution to synthesize nano-ZSM-5 molecular sieves with high crystallinity, which are used for gas-phase alkylation of ethanol and benzene after water vapor treatment and phosphorus modification. Preparation of ethylbenzene. Under relatively low benzyl alcohol (4-6: 1) process conditions, the catalyst not only has high ethyl selectivity, low xylene content in the product, but also has high resistance to hydrothermal stability.

The beneficial effects that this application can produce include:

1) The catalyst preparation process provided by this application is simple, has strong operability, generates little waste water, and can be industrially produced in large quantities.

2) The catalyst prepared by the present application can generate ethylbenzene with high selectivity under relatively low phenol ratio, and the xylene impurity content in the product is low, which saves energy consumption and reduces production cost for subsequent product separation.

3) The catalyst prepared by this application has strong stability, long regeneration period, saves investment cost, and has high applicable value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an XRD pattern of the ZSM-5 catalyst in Example 1 before treatment.

FIG. 2 is an XRD pattern of the ZSM-5 catalyst treated in Example 1. FIG.

FIG. 3a is a SEM image of the ZSM-5 catalyst in Example 1 before treatment; FIG. 3b is a SEM image of the ZSM-5 catalyst in Example 1 after water vapor and phosphoric acid treatment.

FIG. 4 is a schematic diagram of the ethanol conversion rate of the catalyst used in the ethanol to ethylbenzene reaction in Example 1. FIG.

FIG. 5 is a schematic diagram of ethylbenzene selection performance of the catalyst used in the ethanol production reaction of ethylbenzene in Example 1. FIG.

FIG. 6 is a schematic diagram of the content of xylene relative to ethylbenzene in the reaction product of the catalyst used for ethanol to ethylbenzene in Example 1. FIG.

detailed description

The following describes the application in detail with reference to the embodiments, but the application is not limited to these embodiments.

Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels.

Unless otherwise specified, the solvent of the solution used in the examples is water.

The analysis method in the embodiments of the present application is as follows:

X'pert-Pro X-ray diffractometer was used for XRD analysis by PANAnalytical Company of the Netherlands.

SEM analysis was performed using HITACHI S-5500FE-SEM electron microscope.

The PANAlytical Epsilon 5 energy dispersive X-ray fluorescence spectrometer XRF was used for the silicon-aluminum ratio test.

Micromeritics ASAP-2010 type physical adsorption instrument was used for pore structure test.

The conversion rate and selectivity in the examples of the present application are calculated as follows:

In the examples of the present application, the ethanol conversion rate, ethyl selectivity, and relative xylene content are all calculated based on the number of moles of carbon:

Ethanol conversion rate = (moles of ethanol feed-moles of ethanol in the product) / moles of ethanol feed

Ethyl selectivity = (moles of ethylbenzene in the product + moles of diethylbenzene in the product × 2) / moles of ethanol feed

Relative xylene content = moles of xylene in the product / moles of ethylbenzene in the product

Example 1

1) Take 25.0g of ethyl orthosilicate and dissolve it in 12.0g of deionized water, add 10ml of tetrapropylammonium hydroxide solution with a concentration of 3mol / L, stir at room temperature for 1h, put it in a 110 ° C oil bath and crystallize Reflux for 80 h to obtain a ZSM-5 seed gel solution.

2) 20.0 g of tetraethyl silicate, 0.7 g of sodium metaaluminate, 0.3 g of sodium hydroxide, and 7 g of water are mixed uniformly to obtain a mixed solution; the above mixed solution is added to 8.0 g of ZSM-5 seed solution, at room temperature Aging was carried out for 6 hours under stirring, and the solution was placed in a 50 ° C water bath to evaporate the water to dryness to obtain a solid gel.

3) Grind the solid gel into powder and transfer it to the PTFE holder; then add 5ml of deionized water to the hydrothermal kettle, transfer the holder to the hydrothermal kettle, seal, and place it in a 130 ° C oven. Crystallization for 48h; after the crystallized sample is filtered and washed, the filter cake is transferred to an 80 ° C oven for drying for 10h, and then placed in a muffle furnace at 500 ° C for 6h to heat up at 10 ° C / min; the calcined molecular sieve is used for A 1 mol / L ammonium nitrate aqueous solution was exchanged three times in a 70 ° C water bath for 3 hours each time, and then calcined at 500 ° C for 2 hours to obtain a ZSM-5 molecular sieve.

4) The ZSM-5 molecular sieve is placed in a reaction tube and treated with water vapor at 500 ° C. for 2 hours at normal pressure; a 1 mol / L phosphoric acid solution is weighed and the treated sample is mixed at a weight ratio of 5: 1 and placed at 50 ° Stir in a water bath for 2h (300 rpm), then filter and wash until the washing solution becomes neutral, dry the collected solid precipitate at 110 ° C for 12h, and calcine at 550 ° C for 4h to obtain the catalyst, labeled as 1 #.

The XRD patterns of the prepared catalysts before and after treatment, and the SEM images before and after treatment are shown in Figures 1 to 3, respectively. The molecular sieve can still maintain its MFI topology structure after hydrothermal and phosphoric acid modification treatment, and the morphology of the molecular sieve does not change much, which indicates that the synthesized molecular sieve has good resistance to hydrothermal stability.

Example 2

The ethyl orthosilicate in step 1) of Example 1 was replaced with 24.0 g of a silica sol (30 wt%) with an equimolar silicon content, and the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 2 #.

Example 3

The tetrapropylammonium hydroxide solution in step 1) of Example 1 was replaced with 6.3 g of tetraethylammonium bromide in an equimolar amount, and the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 3 #.

Example 4

Replace 20.0 g of tetraethyl silicate, 0.7 g of sodium metaaluminate, 0.3 g of sodium hydroxide in step 2) of Example 1 with 25.0 g of tetraethyl silicate, 0.5 g of sodium metaaluminate, and 0.26 g of hydroxide Sodium, the other synthetic conditions were kept unchanged, and a molecular sieve catalyst was obtained, labeled 4 #.

Example 5

20.0 g of tetraethyl silicate and 0.3 g of sodium hydroxide in step 2) of Example 1 were replaced with 18.0 g of water glass and 0.42 g of potassium hydroxide, and the rest of the synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, labeled 5 #.

Example 6

The 8g ZSM-5 seed solution in step 2) of Example 1 was replaced with 15g ZSM-5 seed solution, and the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 6 #.

Example 7

The 0.7 g of sodium metaaluminate and 8 g of ZSM-5 seed solution in step 2) of Example 1 were replaced with 0.9 g of aluminum nitrate nonahydrate and 12 g of ZSM-5 seed solution, and the remaining synthesis conditions remained unchanged to obtain a molecular sieve. Catalyst, labeled 7 #.

Example 8

1) Take 25.0g of ethyl orthosilicate and dissolve it in 12.0g of deionized water, add 10ml of tetrapropylammonium hydroxide solution with a concentration of 3mol·L ^-1 , stir for 1h at room temperature, and put it in a 110 ℃ oil bath. Crystallize to reflux for 80 h to obtain a ZSM-5 seed gel solution.

2) Mix 18.0g of water glass, 0.7g of aluminum powder, 0.3g of sodium hydroxide and 7g of water to obtain a mixed solution; add the above mixed solution to 10.0g of ZSM-5 seed solution, and stir and age at room temperature for 6h. Placed in a 50 ° C water bath to evaporate the water in the solution to dryness to obtain a solid gel;

3) Grind the solid gel into a powder and transfer it to a PTFE holder; then add 10ml of deionized water to the hydrothermal kettle, transfer the bracket to the hydrothermal kettle, seal, and place it in a 160 ° C oven. 38h; after filtering and washing the crystallized sample, the filter cake was transferred to an oven at 80 ° C for drying for 10h, and then placed in a muffle furnace at 500 ° C for 6h to heat up at a rate of 10 ° C / min; The 1mol / L ammonium nitrate solution was exchanged three times in a 70 ° C water bath for 3h each time, and then calcined at 500 ° C for 2h to obtain ZSM-5 molecular sieve.

4) Place the ZSM-5 molecular sieve in a reaction tube with water vapor at 400 ° C for 3h at normal pressure; weigh a 2mol / L phosphoric acid solution and mix the treated sample with a weight ratio of 5: 1, and place at 50 ° C. Stir in a water bath for 2 h (300 rpm), then filter and wash until the washing solution becomes neutral. The collected solid precipitate is dried at 110 ° C. for 12 h, and calcined at 550 ° C. for 4 h to obtain the catalyst used, which is marked as 8 #.

Example 9

1) Dissolve 20.0 g of ethyl orthosilicate in 12.0 g of deionized water, add 10 ml of a 3 mol / L tetrapropylammonium hydroxide solution, stir at room temperature for 1 h, and place it in a 110 ° C oil bath to crystallize Reflux for 80 h to obtain a ZSM-5 seed gel solution.

2) 20.0 g of tetraethyl silicate, 0.7 g of sodium metaaluminate, 0.3 g of sodium hydroxide, and 7 g of water are mixed uniformly to obtain a mixed solution; the above mixed solution is added to 8.0 g of ZSM-5 seed solution, at room temperature Aged for 6 hours under stirring, and placed in a 50 ° C water bath to evaporate the water in the solution to dryness to obtain a solid gel;

3) Grind the solid gel into powder and transfer it to the PTFE holder; then add 2ml of deionized water to the hydrothermal kettle, transfer the holder to the hydrothermal kettle, seal, and place it in a 180 ° C oven 24h; after filtering and washing the crystallized sample, the filter cake was transferred to an oven at 80 ° C for drying for 10h, and then placed in a muffle furnace at 500 ° C for 6h to heat up at a rate of 10 ° C / min; The 1mol / L ammonium nitrate solution was exchanged three times in a 70 ° C water bath for 3h each time, and then calcined at 500 ° C for 2h to obtain ZSM-5 molecular sieve.

4) The ZSM-5 molecular sieve is placed in a reaction tube and treated with water vapor at 500 ° C. for 2 hours at normal pressure; a 1 mol / L phosphoric acid solution is weighed and the treated sample is mixed at a weight ratio of 5: 1 and placed at 50 ° C. Stir in a water bath for 2h (300 rpm), then filter and wash until the washing solution becomes neutral, dry the collected solid precipitate at 110 ° C for 12h, and calcine at 550 ° C for 4h to obtain the used catalyst, labeled 9 # .

Example 10

The processing time of the water vapor in step 4) of Example 1 was changed from 2h to 4h at 500 ° C under normal pressure, and the remaining synthesis conditions were kept unchanged to obtain a molecular sieve catalyst, labeled 10 #.

Example 11

The phosphorus treatment conditions in step 4) of Example 1 were mixed from a 1 mol / L phosphoric acid solution with the treated sample at a weight ratio of 5: 1 and replaced with a 4 mol / L diammonium hydrogen phosphate solution and the treated sample with The weight ratio of 2: 1 was mixed, and the remaining synthesis conditions were kept unchanged to obtain a molecular sieve catalyst, which was labeled 11 #.

Example 12

The phosphorus treatment conditions in step 4) of Example 1 were mixed from a 1 mol / L phosphoric acid solution and the treated sample at a weight ratio of 5: 1 and replaced with a 0.2 mol / L ammonium dihydrogen phosphate solution and the treated sample. The mixture was mixed at a weight ratio of 30: 1, and the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 12 #.

Example 13

Replace the stirring temperature in step 1) of Example 1 with 25 ° C and the time with 24h; reflux temperature with 80 ° C and the time with reflux with 120h; the rest of the synthesis conditions remain unchanged, and molecular sieve catalysts are obtained, labeled 13 #.

Replace the stirring temperature in step 1) of Example 1 with 40 ° C. and time with 0.5 h; reflux temperature with 160 ° C. and reflux time with 24 h; the remaining synthesis conditions remain unchanged to obtain a molecular sieve catalyst. Marked 14 #.

Example 14

The stirring aging time in step 2) in Example 1 was replaced with 36h, and the temperature of the water bath was replaced with 40 ° C; the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 15 #.

The stirring aging time in step 2) in Example 1 was replaced with 12h, and the temperature of the water bath was replaced with 70 ° C; the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 16 #.

Example 15

Replace the crystallization temperature in step 3) in Example 1 with 120 ° C and the crystallization time with 60h; the roasting temperature before the ammonium nitrate solution exchange is replaced with 300 ° C, the roasting time is 10h, and the heating rate is replaced with 8 ° C / min, the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, labeled 17 #.

Replace the crystallization temperature in step 3) in Example 1 with 180 ° C and the crystallization time with 10h; the roasting temperature before the ammonium nitrate solution exchange is replaced with 600 ° C, the roasting time is 1h, and the heating rate is replaced with 12 ° C / min, the remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, labeled 18 #.

The calcination temperature after the exchange of the ammonium nitrate solution in step 3) in Example 1 was replaced with 600 ° C., and the calcination time was 1 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 19 #.

The calcination temperature after the exchange of the ammonium nitrate solution in step 3) in Example 1 was replaced with 400 ° C., and the calcination time was 3 hours. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 20 #.

Example 16

The temperature of the steam treatment in step 4) in Example 1 was replaced by 300 ° C., and the treatment time was replaced by 10 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 21 #.

The temperature of the steam treatment in step 4) in Example 1 was replaced with 700 ° C., and the treatment time was replaced with 0.5 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 22 #.

The concentration of the phosphoric acid solution in step 4) in Example 1 was replaced by 0.02 mol / L, and the weight ratio of the phosphoric acid solution to the treated sample was replaced by 50: 1. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained. For 23 #.

The concentration of the phosphoric acid solution in step 4) in Example 1 was replaced by 10 mol / L, and the weight ratio of the phosphoric acid solution to the treated sample was replaced by 1: 1. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, labeled as twenty four#.

The temperature of the water bath stirring in step 4) in Example 1 was replaced with 20 ° C., and the stirring time was replaced with 15 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 25 #.

The temperature of the water bath stirring in step 4) in Example 1 was replaced by 90 ° C., and the stirring time was replaced by 0.5 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was marked as 26 #.

The calcination temperature in step 4) in Example 1 was replaced with 200 ° C, and the calcination time was replaced with 10 hours. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 27 #.

The calcination temperature in step 4) in Example 1 was replaced by 90 ° C., and the calcination time was replaced by 1 h. The remaining synthesis conditions were kept unchanged, and a molecular sieve catalyst was obtained, which was labeled 28 #.

The molar ratios of ethyl orthosilicate and tetrapropylammonium hydroxide in step 1) in Example 1 were replaced by 0.5: 1, 2.5: 1, and 5: 1, respectively; the rest of the operations and conditions were the same as in Example 1 to obtain Molecular sieve catalysts are labeled 29 #, 30 # and 31 # respectively.

The stirring rate in the water bath in step 4) in Example 1 was replaced by 400 rpm and 50 rpm, respectively; the rest of the operations and conditions were the same as in Example 1 to obtain a molecular sieve catalyst, labeled 32 # and 33, respectively. #.

Example 17

The physical and chemical properties of the synthetic samples of Examples 1 to 16 were tested. See Table 1 for typical examples, corresponding to the samples in Examples 1 to 12.

Table 1 Physical and chemical properties of molecular sieve samples

Note: The relative crystallinity of the sample is based on Example 1 and is defined as 100%. The rest of the samples are based on the XRD diffraction pattern of the three strongest peaks (2θ = 7.96 °, 8.80 °, 23.16 °). The average of the samples compared.

It can be seen from Table 1 that the particle size distribution of the above synthetic samples is uniform and can be kept within 200nm. The synthesized nano-ZSM-5 molecular sieve has a good pore volume and acid content distribution, and the relative crystallinity of the molecular sieve is mostly Above 70%, the molecular sieve crystallizes well.

The test results of Examples 13 to 16 are similar to the above, the particle size range is 20-500 nm, and the SiO ₂ / Al ₂ O ₃ molar ratio is 50-200.

Example 18

The catalyst (50g) in each of the above embodiments was charged into a reaction tube of a fixed-bed reaction bed for reaction evaluation. The raw materials were benzene and ethanol, and the molar ratio of benzene to ethanol was 4: 1; the reaction temperature was 400 ° C and the mass of ethanol The space velocity is 1.2h ^-1 and the reaction pressure is 1.5MPa. The reaction products were analyzed by online gas chromatography.

The ethanol conversion rate, ethylbenzene selectivity, and xylene content in the product obtained by using the sample of Example 1 as a catalyst are sequentially shown in FIGS. 4 to 6. The reaction results of the above catalysts are shown in Table 2 under the same reaction conditions. It can be seen from the figure that the long-term reaction performance of the reaction is stable, the ethanol conversion rate is> 99%, the ethyl selectivity is> 99%, and the xylene impurity content in the stabilized product is less than 800 ppm.

Comparative Example 1

The catalyst was prepared by referring to the catalyst preparation method of Example 1 disclosed in the patent CN102372580B and used in the experimental reaction conditions in Example 18. The results of the catalytic reaction are shown in Table 2.

Comparative Example 2

The nanometer ZSM-5 (SiO ₂ / Al ₂ O ₃ = 25) produced by the purchased Nankai Molecular Sieve Plant was used as a catalyst, and the same modification treatment as in the catalyst of Example 1 was performed. The modified catalyst was used in the reaction conditions in Example 18. The catalytic reaction results are shown in Table 2. The experimental reaction conditions and catalytic reaction results are shown in Table 2. Table 2 shows the catalyst performance test structures of Examples 1 to 12, Comparative Example 1, and Comparative Example 2.

Table 2 Performance data of catalysts for gas-phase alkylation of ethanol and benzene

The catalytic performance tests of the molecular sieve catalyst samples in Examples 13 to 16 were similar to the results in Table 2. The ethanol conversion rate was above 95%, the ethyl selectivity was above 92%, and the relative xylene content was as low as 610 ppm.

Example 19

The catalyst (50g) in each of the above embodiments was charged into a reaction tube of a fixed-bed reaction bed for reaction evaluation. The raw materials were benzene and ethanol, and the molar ratio of benzene to ethanol was 6: 1; the reaction temperature was 450 ° C and the mass of ethanol The space velocity is 0.8h ^-1 and the reaction pressure is 1.5MPa. The reaction products were analyzed by online gas chromatography. The results of the catalytic reactions of the examples are shown in Table 3.

Comparative Example 3

The catalyst was prepared by referring to the catalyst preparation method of Example 1 disclosed in the patent CN102372580B and used for the reaction conditions in Example 19. The results of the catalytic reaction are shown in Table 3.

Comparative Example 4

The nanometer ZSM-5 (SiO ₂ / Al ₂ O ₃ = 25) produced by the purchased Nankai Molecular Sieve Plant was used as a catalyst, and the same modification treatment as in the catalyst of Example 1 was performed. The modified catalyst was used in the reaction conditions in Example 19, and the catalytic reaction results are shown in Table 3. The experimental reaction conditions and catalytic reaction results are shown in Table 3.

Table 3 Performance data of catalysts for gas-phase alkylation of ethanol and benzene

The catalytic performance tests of the molecular sieve catalyst samples in Examples 13 to 16 were similar to the results in Table 3. The ethanol conversion rate was above 96%, the ethyl selectivity was above 91%, and the relative xylene content was as low as 600 ppm.

Example 20

The sample (50 g) in Example 1 was packed in a reaction tube of a fixed-bed reaction bed for reaction evaluation. The raw materials were benzene and ethanol, and the molar ratio of benzene to ethanol was 5: 1; the reaction temperature was 300 ° C, and the ethanol mass was empty. The speed is 2.5h ^-1 and the reaction pressure is 0.5MPa. The reaction products were analyzed by online gas chromatography. The catalytic effect is similar to the test results of Example 1 in Table 1.

Example 21

The sample (50 g) in Example 1 was charged into a reaction tube of a fixed-bed reactor for reaction evaluation. The raw materials were benzene and ethanol, and the molar ratio of benzene to ethanol was 4: 1; the reaction temperature was 300 ° C, and the ethanol mass was empty. The speed is 2.5h ^-1 and the reaction pressure is 0.5MPa. The reaction products were analyzed by online gas chromatography. The catalytic effect is similar to the test results of Example 1 in Table 1.

Example 22

The phase structure analysis is performed on the molecular sieves obtained in Examples 1 to 16 without water vapor treatment and phosphorus modification, and the corresponding molecular sieve catalysts. Typical examples are shown in FIGS. 1 to 2.

Among them, FIG. 1 is an XRD pattern of the molecular sieve without water vapor treatment and phosphorus modification in Example 1, and FIG. 2 is an XRD pattern of the sample 1 # in Example 1. It can be seen from the figure that the synthesized parent molecular sieve is relatively crystallized It has a high degree. Although the relative crystallinity is significantly reduced after steam treatment and phosphorylation modification, it can still maintain the MFI topology.

The XRD patterns of the molecular sieves that have not been subjected to steam treatment and phosphorus modification and the corresponding molecular sieve catalysts in other embodiments are similar to FIG. 1 and FIG. 2, and the conclusions are similar to the above.

Example 23

Morphological analysis was performed on the molecular sieves obtained in Examples 1 to 16 without water vapor treatment and phosphorus modification, and the corresponding molecular sieve catalysts, as shown in FIG. 3. Among them, Fig. 3a corresponds to the electron microscope photograph of the molecular sieve obtained in Example 1 without post-treatment, and Fig. 3b corresponds to the electron microscope photograph of the molecular sieve obtained in Example 1 after water vapor and phosphoric acid modification treatment; The particle distribution is more uniform. Some small particles appear on the molecular sieves modified by water vapor and phosphoric acid, but most of the particle morphologies have not changed significantly.

The SEM images of the molecular sieves that have not been subjected to steam treatment and phosphorus modification and the corresponding molecular sieve catalysts in other embodiments are similar to FIG. 3a and FIG. 3b, respectively, and the conclusions are similar to the above.

The above are just a few examples of the present application, and do not limit the application in any way. Although the present application is disclosed in the preferred embodiment as above, it is not intended to limit the application. Any person skilled in the art, Without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to an equivalent implementation case, and all fall within the scope of the technical solution.

Claims

A method for preparing a molecular sieve catalyst, comprising:

(1) obtaining a ZSM-5 seed gel solution;

(2) adding the mixture I containing a silicon source, an aluminum source, an alkali and water to the ZSM-5 seed gel solution described in step (1) to obtain a mixture II, and aging to obtain a solid gel;

(3) Under a sealed condition, the solid gel water-vapor-assisted crystallization described in step (2), roasting I, ammonium ion exchange, roasting II to obtain nano ZSM-5 molecular sieve;

(4) The nano-ZSM-5 molecular sieve obtained in step (3) is subjected to steam treatment and phosphorus modification, and calcined III to obtain the molecular sieve catalyst.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the method for obtaining the ZSM-5 seed gel solution in step (1) comprises: stirring a solution containing a silicon source and a template agent, and then refluxing To obtain the ZSM-5 seed gel solution.
The method for preparing a molecular sieve catalyst according to claim 2, characterized in that the molar ratio of the silicon source and the template is 0.5 to 5: 1;

The stirring conditions are: stirring at 25-40 ° C in a water bath for 0.5-24 hours;

The conditions for the reflux are: in an oil bath at 80 to 160 ° C., the reflux treatment is performed for 24 to 120 hours.
The method for preparing a molecular sieve catalyst according to claim 3, wherein the silicon source is at least one selected from the group consisting of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate;

The template agent is selected from at least one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetraethylammonium bromide, tetraethylammonium hydroxide, and tetrapropylammonium chloride.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the molar ratio of silicon source, aluminum source, alkali and water in the mixture I in step (2) satisfies:

SiO 2 : Al 2 O 3 : M 2 O: H 2 O = 10 ～ 300: 1: 0.1 ～ 20: 10 ～ 200;

Among them, water is calculated in the number of moles of H 2 O itself, silicon source is calculated in the number of moles of SiO 2 , aluminum source is calculated in the number of moles of Al 2 O 3 , and alkali is calculated in the number of moles of alkali metal oxide; where M is alkali metal;

The ZSM-5 seed gel solution is 5% to 50% of the total mass of the mixture II.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the silicon source in step (2) is selected from at least one of tetraethyl orthosilicate, silica sol, water glass, and sodium silicate;

The aluminum source is selected from at least one of sodium metaaluminate, aluminum powder, aluminum nitrate, and aluminum hydroxide;

The base is selected from at least one of sodium hydroxide and potassium hydroxide.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the aging conditions in step (2) are: stirring at room temperature for 6 to 36 hours, and then stirring in a water bath at 40 to 70 ° C.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the conditions of the water vapor-assisted crystallization in step (3) are: crystallization at 120 to 180 ° C for 10 to 60 hours.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the conditions for the roasting I in step (3) are: firing at 300 to 600 ° C for 1 to 10 hours;

The conditions for the roasting II are: roasting at 400 to 600 ° C for 1 to 3 hours.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the conditions for the water vapor treatment in step (4) are: pressure is normal pressure, temperature is 300-700 ° C, and time is 0.5-10 hours.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the conditions for the phosphorus modification in step (4) are: placing the sample to be treated in a phosphorus-containing solution, and stirring;

The mass ratio of the phosphorus-containing solution to the sample to be processed is 1-50.
The method for preparing a molecular sieve catalyst according to claim 11, wherein the concentration of the phosphorus-containing solution is 0.02 to 10 mol / L;

The stirring conditions are: stirring in a water bath at 20 to 90 ° C for 0.5 to 15 hours, and the stirring speed is 50 to 400 rpm.
The method for preparing a molecular sieve catalyst according to claim 11, wherein the phosphorus source of the phosphorus-containing solution comprises at least one of phosphoric acid, diammonium phosphate, diammonium phosphate, and ammonium phosphate;

The concentration of the phosphorus-containing solution is 0.1 to 5 mol / L.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the conditions for the calcination III in step (4) are: calcination at 200 to 700 ° C for 1 to 10 hours.
The method for preparing a molecular sieve catalyst according to claim 1, wherein the molecular sieve catalyst is a small-grain ZSM-5 molecular sieve with a grain diameter of 20 to 500 nm.
The method for preparing a molecular sieve catalyst according to claim 15, wherein the molecular sieve catalyst has a crystal grain diameter of 50 to 300 nm.
The method for preparing a molecular sieve catalyst according to claim 15, wherein the molecular sieve catalyst has a silicon-aluminum molar ratio SiO 2 / Al 2 O 3 of 50-200.
The method for preparing a molecular sieve catalyst according to claim 17, wherein the molecular sieve catalyst has a silicon-aluminum molar ratio SiO 2 / Al 2 O 3 of 80-140.
The method for preparing a molecular sieve catalyst according to claim 1, comprising:

1) Seed Synthesis

The silicon source was weighed and dissolved in deionized water, and a template agent was added, and the mixture was stirred in a water bath at 25 to 40 ° C for 0.5 to 24 hours; then transferred to an oil bath at 80 to 160 ° C and subjected to reflux treatment for 24 to 120 hours to obtain a seed gel solution. ;

2) Preparation of xerogel

The silicon source, aluminum source, alkali, and water were weighed according to the ratio and stirred to obtain a mixture. The molar ratios of the materials in the mixture were SiO 2 , Al 2 O 3 , M 2 O, and H 2 O, respectively. SiO 2 : Al 2 O 3 : M 2 O: H 2 O = 10 ～ 300: 1: 0.1 ～ 20: 10 ～ 200, where M is an alkali metal; add the above mixture to the seed gel solution, and stir at room temperature for 12 ～ 36h , Placed in a water bath at 40 to 70 ° C and stirred to evaporate water in the solution to obtain a solid gel;

Among them, water is calculated in the number of moles of H 2 O itself, silicon source is calculated in the number of moles of SiO 2 , aluminum source is calculated in the number of moles of Al 2 O 3 , and alkali is calculated in the number of moles of alkali metal oxide; where M is alkali metal;

3) Synthesis of ZSM-5 molecular sieve

The solid gel is ground into a powder and placed on a bracket; the whole is placed in a hydrothermal kettle containing 1-10 ml of water and sealed; placed at 120-180 ° C for crystallization and kept at a constant temperature for 10-60 hours; The product was filtered and washed until the washing solution became neutral, filtered, and dried at 60 to 120 ° C; then the sample was baked at 300 to 600 ° C for 1 to 10 hours; then, ammonium exchange and roasted to obtain ZSM-5 molecular sieve;

Wherein, the conditions for the ammonium ion exchange are: 3 times exchange with a 1 mol / L ammonium nitrate solution in a 70 ° C water bath condition;

4) Post-treatment of ZSM-5 molecular sieve

The sample obtained in 3) is subjected to steam treatment, wherein the processing conditions are normal pressure, the temperature is 300-700 ° C, and the time is 0.5-10 hours; the treated sample is placed in a phosphorus-containing solution in a water bath, and the phosphorus-containing solution is stirred. The concentration is 0.02 to 10 mol / L, the water bath temperature is 20 to 90 ° C, the stirring speed is 50 to 400 rpm, and the time is 0.5 to 15 hours; the treated sample is filtered and washed until the washing solution becomes neutral, and filtered, Drying treatment is performed at 60 to 120 ° C; the sample is then baked at 200 to 700 ° C for 1 to 10 hours to obtain the molecular sieve catalyst.
A catalyst for preparing ethylbenzene by gas-phase alkylation of ethanol and benzene, comprising at least one of molecular sieve catalysts prepared by the method according to any one of claims 1 to 19.
A method for preparing ethylbenzene by gas-phase alkylation of ethanol and benzene, which comprises: reacting a raw material containing ethanol and benzene through a fixed-bed reactor containing a catalyst to obtain ethylbenzene;

The catalyst is selected from at least one molecular sieve catalyst prepared by the method according to any one of claims 1 to 19.
The method for preparing ethylbenzene by gas-phase alkylation of ethanol and benzene according to claim 21, wherein the reaction conditions are:

The molar ratio of benzene to ethanol is 4 to 6: 1; the mass space velocity of ethanol is 0.5 to 2.5 h -1 , the reaction pressure is 0.5 to 2.5 MPa, and the reaction temperature is 300 to 500 ° C.