Method for preparing ethylbenzene through liquid phase alkylation

Abstract

The invention relates to a method for preparing ethylbenzene through liquid-phase alkylation, which comprises the following steps: contacting ethylene-containing raw material dry gas and benzene with a catalyst, and carrying out liquid-phase alkylation reaction to obtain a reaction product containing ethylbenzene, wherein the conditions of the liquid phase alkylation reaction are as follows: the reaction temperature is 100-300 DEG C, the reaction pressure is 1.0-4.0 MPa, the molar ratio of benzene to ethylene is (2: 1)-(8: 1), and the weight space velocity of ethylene is 0.2-2.0 h <-1 >; based on the total weight of the catalyst, the catalyst comprises 60-90 wt% of a three-dimensional twelve-membered ring molecular sieve and 40-10 wt% of an aluminum-containing oxide, the three-dimensional twelve-membered ring molecular sieve comprises a BEA structure molecular sieve, and the molar ratio of SiO2 to Al2O3 is 4-30. The method can solve the problems of low purity and high energy consumption of ethylbenzene products prepared by a gas phase method.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and in particular, to a method for preparing ethylbenzene by liquid phase alkylation. Background Art

[0002] Ethylbenzene is an important basic chemical raw material, which is mainly used as a raw material for the production of styrene monomer. Styrene is an important monomer for the synthesis of polymer materials, mainly used to produce polystyrene and copolymer ABS resin, etc. In recent years, my country's demand for styrene, especially high-quality styrene, has been increasing. At present, the production of ethylbenzene mainly adopts the production method of alkylation of benzene and ethylene.

[0003] According to the different sources of ethylene, the production process of ethylbenzene is divided into pure ethylene process (the raw material ethylene is polymerization grade ethylene) and crude ethylene (the raw material is dry gas containing ethylene, generally referring to catalytic cracking dry gas, ethane cracking gas or catalytic cracking dry gas) process; according to the different phases of the alkylation reaction, it can be divided into liquid phase process and gas phase process. The liquid phase process has mild reaction conditions, and the quality of ethylbenzene products prepared is better than that of the gas phase process, and the energy and material consumption are lower. Regardless of pure ethylene or crude ethylene units, it is the preferred process route for industrialization. At present, all newly built pure ethylene ethylbenzene units adopt the liquid phase process route, and the ethylbenzene produced by the liquid phase ethylbenzene process route accounts for more than 90% of the total ethylbenzene production. However, the raw material ethylene of the liquid phase process is usually polymerization grade ethylene. More than 95% of ethylene in the world is obtained by steam cracking technology, which has a complex process and high investment.

[0004] In addition, as crude oil becomes heavier and worse, the shortage of light hydrocarbon raw materials for steam cracking is becoming increasingly serious, resulting in the economic benefits of pure ethylene liquid phase production of ethylbenzene technology being limited. In response to the above situation, a heavy oil catalytic cracking (DCC) process using heavy oil as raw material has been developed. The ethylene mass fraction in the dry gas produced by this technology is 12-40%, which can directly react with benzene to produce ethylbenzene. Chinese patent ZL200510011505.9 discloses a catalyst for catalyzing the production of ethylbenzene from ethylene and benzene in dry gas, as well as a preparation method and application. When the catalyst is used to catalyze the production of ethylbenzene from ethylene and benzene in dry gas, the catalytic dry gas contains 10-60% ethylene, 100-5000ppm H2S, 1.0-5.0%v COx, 0.1-1.5%v oxygen, and 1000-4000ppm water. The conversion rate of ethylene is above 95%, the selectivity of ethylbenzene is above 90%, the selectivity of ethylation is above 99%, and the xylene content in pure ethylbenzene is less than 100ppm. Other related patents include ZL200610046750.8, ZL200510105256.X, ZL200410037433.0, ZL200410021102.8, ZL201110105517.3, ZL201510324493.9, etc. These technologies use catalytic dry gas to remove propylene and then directly enter the alkylation reactor to react with benzene for alkylation. However, due to the use of the gas phase method, this technology has the problems of high reaction temperature, high energy consumption, high material consumption and high xylene content in the ethylbenzene product.

[0005] In recent years, based on the fact that the heavy oil catalytic cracking (DCC) process is not suitable for processing low-quality heavy oil raw materials, a new high-efficiency catalytic cracking (RTC) process technology using low-quality heavy oil as raw material has been developed; based on the comprehensive utilization of dry gas from large refineries and the utilization of ethane, ethane cracking technology has been developed, and the mass fraction of ethylene in the dry gas of the above process has been further increased to 40-70%, and the concentration has been greatly increased. The above dry gas market price advantage is obvious. Using ethylene in dry gas as raw material to produce ethylbenzene (catalytic dry gas to ethylbenzene process) can greatly increase its added value and have good economic benefits. If the problems of high energy consumption and high xylene content can be solved, it will be of great significance both in terms of raw material cost and product quality. The liquid phase method can solve the above problems, but due to the low operating temperature of the liquid phase method and the slow diffusion of the reactants in the micropores of the molecular sieve, the liquid phase method often uses molecular sieves with larger pore sizes, such as MWW (MCM-22, etc.) molecular sieves. However, in addition to ethylene, concentrated ethylene dry gas also contains non-olefin substances such as ethane and methane, which reduces the probability of ethylene contacting the active center of the catalyst, leading to problems such as low activity and poor selectivity, and the dry gas-liquid phase method has not been industrialized. The reason for the immaturity of the catalyst is that it cannot adapt to the gas-liquid-solid three-phase reaction at low temperatures, and its activity and selectivity are low.

[0006] CN107827692B discloses a method for producing ethylbenzene from high-concentration ethylene gas, including the following process: dividing the raw material concentrated ethylene dry gas into multiple strands and correspondingly entering multiple absorption towers; the first absorption tower additionally provides raw material benzene as an absorbent; the gaseous material coming out of the absorption tower enters the gas phase alkylation reactor for treatment; and the liquid material enters the liquid phase alkylation reactor for reaction; the material after the liquid phase alkylation reaction is divided into two strands, wherein the first strand of material returns to the absorption tower of this level as an absorbent, and the second strand of material enters the next level absorption tower as an absorbent; after the strand splitting reaction, one strand of the material finally formed returns to the last absorption tower, and the other strand enters the benzene recovery tower; the ethylbenzene-rich material is extracted from the benzene recovery tower and enters the ethylbenzene recovery tower to form ethylbenzene distillate. This patent mainly adopts a liquid phase production process, with a low reaction temperature, and has the advantages of energy saving and environmental protection, a high product conversion rate, and the xylene content produced is controlled below 100ppm, and the product quality is good. Although the above patents are reports on the partial liquid phase method for preparing ethylbenzene from dry gas, the process flow is complicated, and major changes need to be made to the existing process, and the catalyst performance itself has not been improved. Summary of the invention

[0007] The purpose of the present disclosure is to provide a method for preparing ethylbenzene by liquid phase alkylation, so as to solve the problems of low purity and high energy consumption of ethylbenzene produced by gas phase method.

[0008] In order to achieve the above object, the present disclosure provides a method for preparing ethylbenzene by liquid phase alkylation, comprising the following steps:

[0009] The raw material dry gas containing ethylene and benzene are contacted with a catalyst to carry out a liquid phase alkylation reaction to obtain a reaction product containing ethylbenzene; wherein the conditions of the liquid phase alkylation reaction include: a reaction temperature of 140 to 200°C, a reaction pressure of 1.0 to 4.0 MPa, a benzene / ethylene molar ratio of 2:1 to 8:1, and an ethylene weight space velocity of 0.2 to 2.0 h -1 ; Based on the total weight of the catalyst, the catalyst contains 60 to 90 weight % of a three-dimensional twelve-membered ring molecular sieve and 10 to 40 weight % of an aluminum-containing oxide; the three-dimensional twelve-membered ring molecular sieve includes a BEA structure molecular sieve, and the molar ratio of SiO2 / Al2O3 is 4 to 30.

[0010] Optionally, the BEA structure molecular sieve is prepared by a method comprising the following steps:

[0011] S1, mixing a silicon source, an aluminum source, a template, an alkali and water to form a raw material mixture;

[0012] S2, subjecting the raw material mixture to a first crystallization treatment under a first crystallization condition, and then to a second crystallization treatment under a second crystallization condition;

[0013] Preferably, in step S1, the silicon source is calculated as SiO2, the aluminum source is calculated as A12O3, the molar ratio of SiO2 / A12O3 in the raw material mixture is 4-60, preferably 6-30, the molar ratio of H2O / SiO2 is 6-60, preferably 8-40, the molar ratio of template / SiO2 is 0.1-0.28, preferably 0.1-0.14, and the molar ratio of NaOH / SiO2 is 0.01-0.2, preferably 0.1-0.15.

[0014] Optionally, in step S1, the silicon source is selected from one or more of amorphous silica, silica sol, silica gel, diatomaceous earth and water glass; the aluminum source is selected from one or more of aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride and aluminum oxide; the base is an inorganic base, preferably the base is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide; the template is selected from one or more of tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

[0015] Optionally, in step S2, the first crystallization conditions include: temperature of 80-140° C., time of 12-48 h, and pressure of autogenous pressure; preferably, temperature of 110-130° C., time of 18-24 h;

[0016] The second crystallization conditions include: temperature of 100-180°C, time of 24-72h, and pressure of autogenous pressure; preferably, temperature of 120-160°C, time of 36-60h;

[0017] Optionally, after step S2, the method further includes: washing and drying the solid product obtained by the second crystallization treatment.

[0018] Optionally, the catalyst is prepared by a method comprising the following steps:

[0019] S3, mixing the three-dimensional twelve-membered ring molecular sieve and the binder, performing a molding process, a first drying process and a first calcination process to obtain a first product;

[0020] S4, subjecting the first product to a second drying treatment and a second calcination treatment.

[0021] Optionally, the conditions of the first calcination treatment include: calcination at 200-350° C. for 1-4 h in a water vapor atmosphere, with a water flow rate of 0.02-0.2 ml / g min; then calcination at 300-500° C. for 0.2-1 h in an ammonia vapor atmosphere, with an ammonia concentration of 0.01-0.1 mol / L and an ammonia flow rate of 0.02-0.2 ml / g min;

[0022] Preferably, the calcination is carried out at 250-300°C for 2-3h under a water vapor atmosphere, with a water flow rate of 0.04-0.08ml / gmin; and then the calcination is carried out at 350-450°C for 0.5-0.8h under an ammonia vapor atmosphere, with an ammonia concentration of 0.02-0.06mol / L and an ammonia flow rate of 0.04-0.15ml / g min;

[0023] Optionally, the second calcination conditions include: a calcination temperature of 300-600° C., and a calcination time of 1-4 hours. Preferably, the calcination temperature is 400-500° C., and the calcination time is 2-3 hours.

[0024] Optionally, the binder is selected from one or more of alumina, aluminum sol and pseudo-boehmite;

[0025] Preferably, based on the total weight of the three-dimensional twelve-membered ring molecular sieve and the binder, the content of the three-dimensional twelve-membered ring molecular sieve is 50 to 90% by weight, preferably 60 to 80% by weight.

[0026] Optionally, the conditions of the liquid phase alkylation reaction include: reaction temperature of 120-220°C, reaction pressure of 1.0-4.0 MPa, benzene / ethylene molar ratio of 4:1-8:1, ethylene weight space velocity of 0.5-2.0 h -1 ;

[0027] Optionally, the raw dry gas containing ethylene includes one or more of catalytic cracking dry gas, ethane cracking dry gas, coking dry gas and methanol to olefins crude ethylene gas; preferably, the ethylene concentration in the raw dry gas is above 40 volume %; preferably 50-100 volume %.

[0028] Optionally, the BEA structure molecular sieve is a beta molecular sieve; preferably, the molar ratio of SiO2 / Al2O3 of the beta molecular sieve is 6 to 30, preferably 6 to 25;

[0029] Preferably, the average particle size of the beta molecular sieve is 0.01 to 0.2 μm, preferably 0.04 to 0.1 μm; the BET specific surface area is 400 to 700 m 2 / g, preferably 450 to 650 m 2 / g; total pore volume is 0.4~0.8cm 3 / g, preferably 0.5 to 0.8 cm 3 / g.

[0030] Optionally, based on the total weight of the catalyst, the catalyst comprises 60 to 80 weight percent of a three-dimensional twelve-membered ring molecular sieve and 20 to 40 weight percent of an aluminum-containing oxide;

[0031] Preferably, the aluminum-containing oxide is selected from one or more of aluminum oxide, aluminum sol and aluminum oxide-silicon oxide mixture; preferably aluminum sol and / or aluminum oxide.

[0032] Through the above technical scheme, the present disclosure provides a method for preparing ethylbenzene by liquid phase alkylation, which can realize the preparation of ethylbenzene under liquid phase reaction conditions, effectively improve the contact between ethylene and benzene molecules on the catalyst surface, inhibit the polymerization of ethylene itself, change the electric field structure in the catalyst pores, promote the adsorption of benzene, and inhibit the formation of diethylbenzene, thereby improving the ethylene conversion activity and ethylbenzene selectivity; compared with the liquid phase alkylation reaction of preparing ethylbenzene using low silicon-aluminum ratio beta molecular sieve and conventional beta molecular sieve, the method for preparing ethylbenzene provided by the present disclosure can achieve nearly complete conversion of ethylene at low temperature, high ethylation selectivity, and achieve the purpose of significantly reducing energy consumption and xylene content.

[0033] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0035] Figure 1 OH-IR spectra of the molecular sieves obtained in Preparation Example 1 and Comparative Example 1;

[0036] Figure 2 NH3-TPD spectra of the molecular sieves obtained in Preparation Example 1 and Comparative Example 1;

[0037] Figure 3 The XRD spectrum of the catalyst obtained in Preparation Example 1 is shown in FIG. DETAILED DESCRIPTION

[0038] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0039] The present disclosure provides a method for preparing ethylbenzene by liquid phase alkylation, comprising the following steps:

[0040] The raw material dry gas containing ethylene and benzene are contacted with a catalyst to carry out a liquid phase alkylation reaction to obtain a reaction product containing ethylbenzene; wherein the conditions of the liquid phase alkylation reaction include: a reaction temperature of 140 to 200°C, a reaction pressure of 1.0 to 4.0 MPa, a benzene / ethylene molar ratio of 2:1 to 8:1, and an ethylene weight space velocity of 0.2 to 2.0 h -1; Based on the total weight of the catalyst, the catalyst contains 60 to 90 weight % of a three-dimensional twelve-membered ring molecular sieve and 10 to 40 weight % of an aluminum-containing oxide; the three-dimensional twelve-membered ring molecular sieve includes a BEA structure molecular sieve, and the molar ratio of SiO2 / Al2O3 is 4 to 30.

[0041] The present disclosure provides a method for preparing ethylbenzene by liquid phase alkylation, which can realize the preparation of ethylbenzene under liquid phase reaction conditions, effectively improve the contact between ethylene and benzene molecules on the catalyst surface, inhibit the polymerization of ethylene itself, change the electric field structure in the catalyst pores, promote the adsorption of benzene, and inhibit the formation of diethylbenzene, thereby improving the ethylene conversion activity and ethylbenzene selectivity. Compared with the liquid phase alkylation reaction of preparing ethylbenzene using low silicon-aluminum ratio beta molecular sieve and conventional beta molecular sieve, the method for preparing ethylbenzene provided by the present disclosure can achieve nearly complete conversion of ethylene at low temperature, high ethylation selectivity, and achieve the purpose of significantly reducing energy consumption and xylene content.

[0042] In a preferred embodiment, the conditions of the liquid phase alkylation reaction include: reaction temperature of 120-220°C, reaction pressure of 1.0-4.0 MPa, benzene / ethylene molar ratio of 4:1-8:1, ethylene weight space velocity of 0.5-2.0 h -1 By preparing ethylbenzene according to the reaction conditions of this embodiment, a higher ethylene conversion rate and ethylation product selectivity can be obtained.

[0043] In a specific embodiment, the raw material dry gas containing ethylene includes one or more of catalytic cracking dry gas, ethane cracking dry gas, coking dry gas, and methanol to olefins crude ethylene gas; preferably, the ethylene concentration in the raw material dry gas is above 40 volume %; preferably 50-100 volume %.

[0044] In a preferred embodiment, the BEA structure molecular sieve is a beta molecular sieve; preferably, the molar ratio of SiO2 / Al2O3 of the beta molecular sieve is 6 to 30, preferably 6 to 25.

[0045] In a specific embodiment, the average particle size of the beta molecular sieve is 0.01 to 0.2 μm, preferably 0.04 to 0.1 μm; the BET specific surface area is 400 to 700 m 2 / g, preferably 450 to 650 m 2 / g; total pore volume is 0.4~0.8cm 3 / g, preferably 0.5 to 0.8 cm 3 / g.

[0046] In a preferred embodiment, in the OH-IR spectrum of the beta molecular sieve, at a wave number of 3610±40cm -1There is a first characteristic signal peak at the position, and the peak area of ​​the first characteristic signal peak is recorded as A1; at a wave number of 3775±40cm -1 There is a second characteristic signal peak at the position, and the peak area of ​​the second characteristic signal peak is recorded as A2; preferably, A1 / (A 1+ The value of A2)×100% is 50 to 70%, preferably 59 to 68%.

[0047] In a preferred embodiment, in the NH3-TPD spectrum of the catalyst, the proportion of strong acid to acid is 35-60%, preferably 40-50%. The high temperature (300-450°C) desorption peak in the NH3-TPD spectrum corresponds to the acid amount of the strong acid in the catalyst, and the low temperature (150-300°C) desorption peak corresponds to the weak acid amount. According to the present disclosure, the proportion of strong acid to acid is calculated by the following method: high temperature desorption peak area / (high temperature desorption peak+low temperature desorption peak area)×100%.

[0048] In a preferred embodiment, based on the total weight of the catalyst, the catalyst comprises 60 to 80 weight percent of a three-dimensional twelve-membered ring molecular sieve and 20 to 40 weight percent of an aluminum-containing oxide;

[0049] Preferably, the aluminum-containing oxide is selected from one or more of aluminum oxide, aluminum sol and aluminum oxide-silicon oxide mixture; preferably aluminum sol and / or aluminum oxide.

[0050] In a preferred embodiment, the BEA structured molecular sieve is prepared by a method comprising the following steps:

[0051] S1, mixing a silicon source, an aluminum source, a template, an alkali and water to form a raw material mixture;

[0052] S2, subjecting the raw material mixture to a first crystallization treatment under a first crystallization condition, and then to a second crystallization treatment under a second crystallization condition;

[0053] Preferably, in step S1, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the molar ratio of SiO2 / Al2O3 in the raw material mixture is 4 to 60, preferably 6 to 30, the molar ratio of H2O / SiO2 is 6 to 60, preferably 8 to 40, the molar ratio of template / SiO2 is 0.1 to 0.28, preferably 0.1 to 0.14, and the molar ratio of NaOH / SiO2 is 0.01 to 0.2, preferably 0.1 to 0.15. The molecular sieve prepared by the method provided in this embodiment is used in the catalyst for liquid phase alkylation to ethylbenzene, which can further improve the catalytic reaction effect.

[0054] In one embodiment, in step S1, the silicon source is selected from one or more of amorphous silica, silica sol, silica gel, diatomaceous earth and water glass; the aluminum source is selected from one or more of aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride and aluminum oxide; the base is an inorganic base, preferably the base is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide; the template is selected from one or more of tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

[0055] In one embodiment, in step S2, the first crystallization conditions include: temperature of 80-140° C., time of 12-48 hours, and pressure of autogenous pressure; preferably, temperature of 110-130° C., time of 18-24 hours;

[0056] The second crystallization conditions include: temperature of 100-180°C, time of 27-72h, and pressure of autogenous pressure; preferably, temperature of 120-160°C, and time of 36-60h. The present disclosure uses two stages of crystallization treatment to help improve the crystallinity of the molecular sieve, and the morphology of the molecular sieve is more regular.

[0057] In a specific embodiment, after step S2, the method further includes: washing and drying the solid product obtained from the second crystallization treatment.

[0058] In one embodiment, the catalyst is prepared by a method comprising the following steps:

[0059] S3, mixing the three-dimensional twelve-membered ring molecular sieve and the binder, performing a molding process, a first drying process and a first calcination process to obtain a first product;

[0060] S4, subjecting the first product to a second drying treatment and a second calcination treatment.

[0061] In a preferred embodiment, the conditions of the first calcination treatment include: calcining at 250-300°C for 1-4h in a water vapor atmosphere, with a water flow rate of 0.02-0.2ml / g min; then calcining at 300-500°C for 0.2-1h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.01-0.1mol / L and the ammonia flow rate is 0.02-0.2ml / g min. The first calcination treatment conditions provided in this embodiment use a special atmosphere protection procedure to activate the catalyst, the framework aluminum of the beta catalyst is retained to the maximum extent, and the amount of B acid is not easily lost; under the programmed calcination conditions of water vapor and ammonia vapor, the aluminum sol inhibits the removal of the framework aluminum on the one hand, and on the other hand, the framework aluminum migrates to the surface of the molecular sieve to form new active centers. When used for the liquid-phase alkylation reaction of high-concentration ethylene and benzene, the contact between ethylene and benzene molecules on the catalyst surface is effectively improved, the polymerization of ethylene itself is inhibited, the electric field structure in the catalyst pores is changed, the adsorption of benzene is promoted, and the formation of diethylbenzene is inhibited, thereby improving the ethylene conversion activity and ethylbenzene selectivity.

[0062] In a preferred embodiment, the conditions of the first calcination treatment include: calcining at 250-300°C for 2-3 hours in a water vapor atmosphere, with a water flow rate of 0.04-0.08 ml / g min; then calcining at 350-450°C for 0.5-0.8 hours in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.02-0.06 mol / L and the ammonia flow rate is 0.04-0.15 ml / g min.

[0063] In one embodiment, the second calcination conditions include: a calcination temperature of 300-600° C. and a calcination time of 1-4 hours. Preferably, the calcination temperature is 400-500° C. and the calcination time is 2-3 hours.

[0064] In one embodiment, the binder is selected from one or more of alumina, alumina sol and pseudo-boehmite;

[0065] Preferably, based on the total weight of the three-dimensional twelve-membered ring molecular sieve and the binder, the content of the three-dimensional twelve-membered ring molecular sieve is 50 to 90% by weight, preferably 60 to 80% by weight.

[0066] The present disclosure is further described in detail by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0067] In the following embodiments and comparative examples:

[0068] The OH-IR test instrument of the molecular sieve is the FTS 3000 Fourier transform infrared spectrometer produced by BIQ-RAD Company of the United States. The test conditions include pressing the sample into a tablet and sealing it in the in-situ cell of the infrared spectrometer. Evacuate to 10- 3 Pa, keep constant temperature for 60 min, then cool to room temperature, measure wavenumber range 3000~4000cm -1 ;

[0069] The test instrument for NH3-TPD of molecular sieve is Autochem II 2920 programmed temperature desorber produced by Micromeritics. The test conditions include weighing 0.1g of molecular sieve sample with a particle size of 20-40 mesh and loading it into a sample tube, placing it in a thermal conductivity cell heating furnace, using He gas with a flow rate of 50ml / min as a carrier gas to heat it to 600℃ and purge it for 1h to remove the adsorbent on the surface of the sample. Then cool it to 100℃, keep the temperature constant for 30min, switch to NH3 / He mixed gas (10% NH3+90% He) for adsorption for 30min, and then switch to He gas purge for 90min until the baseline is stable to remove NH3 that exists on the sample surface by physical adsorption. Desorption is carried out by heating it to 600℃ at a heating rate of 10℃ / min. The desorption amount of NH3 is determined by a TCD detector during the NH3 desorption process.

[0070] Unless otherwise specified, the raw materials used in the examples are all chemically pure reagents.

[0071] The following preparation examples were used to synthesize the catalyst.

[0072] Preparation Example 1

[0073] (1) Sodium aluminate, sodium hydroxide, coarse silica gel, tetraethylammonium hydroxide (TEAOH) and deionized water were added to a beaker at a molar ratio of SiO2 / A12O3=20, H2O / SiO2=8, TEAOH / SiO2=0.1 and NaOH / SiO2=0.1. After stirring at room temperature for 6 hours, the mixture was transferred to a crystallization kettle and crystallized at 120°C for 1 day (24 hours). The mixture was then heated to 140°C and crystallized for 2 days (48 hours). The crystallization solution was centrifuged, washed, filtered and dried to obtain a beta molecular sieve (molar ratio of SiO2 / Al2O3 is 18). The XRD spectrum of the molecular sieve is shown in FIG. Figure 3 As shown, it is shown that the prepared molecular sieve has a beta molecular sieve structure.

[0074] (2) The molecular sieve powder and aluminum sol in step (1) are mixed in a mass ratio of 70:30 (the content of the molecular sieve powder is 70% by weight), and kneaded into a shape. Take 20g of the molded molecular sieve, first roast it at 270°C for 3h in a water vapor atmosphere, with a water flow rate of 0.06ml / g min; then roast it at 400°C for 0.5h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.05mol / L and the flow rate is 0.06ml / g min; after drying the obtained product, roast it at 450°C for 2.5h in an air atmosphere, and the obtained catalyst product is recorded as Cat-1.

[0075] Preparation of Comparative Example 1

[0076] This preparation comparative example refers to the preparation method in Preparation Example 1, and the difference from Preparation Example 1 is that: in step (1), sodium aluminate, sodium hydroxide, coarse silica gel, tetraethylammonium hydroxide (TEAOH) and deionized water are added to a beaker at a molar ratio of SiO2 / A12O3=3, H2O / SiO2=6, TEAOH / SiO2=0.1, NaOH / SiO2=0.1, and the rest of the process is the same as Preparation Example 1. The molar ratio of SiO2 / Al2O3 of the prepared molecular sieve is 3, and the obtained catalyst product is recorded as DB-1.

[0077] The OH-IR spectra of the molecular sieves obtained in Preparation Example 1 and Comparative Example 1 are as follows: Figure 1 As shown by Figure 1 It can be seen that the molecular sieve has a wave number of 3610cm -1 The peak at wave number 3775 cm -1 The peak at corresponds to the non-tetracoordinated aluminum connected to the framework. Figure 1 Preparation Example 1 adopts the method disclosed in the present invention, which can effectively protect the tetra-coordinated aluminum of the molecular sieve framework.

[0078] The NH3-TPD spectra of the catalysts obtained in Preparation Example 1 and Comparative Example 1 are as follows: Figure 2 As shown by Figure 2 It can be seen that the total acid amount at 200°C corresponds to the weak amount of the catalyst, and the total acid amount at 350°C corresponds to the amount of strong acid in the catalyst. It can be seen from the figure that Preparation Example 1 can effectively increase the amount of medium and strong acid in the beta molecular sieve; the results of the proportion of strong acid to acid amount in the NH3-TPD spectrum are listed in Table 1.

[0079] Preparation Comparative Example 2

[0080] This preparation comparative example refers to the preparation method in Preparation Example 1, and the difference from Preparation Example 1 is that: in step (2), the molecular sieve raw powder of step (1) is mixed with alumina in a mass ratio of 70:30, and pressed into tablets to obtain a molecular sieve mixed with a binder. After taking 20 g, it is mixed with NH4Cl and deionized water in a ratio of 1:1:10, stirred at 80°C for 4h, centrifuged, filtered, dried, and then calcined at 550°C in an air atmosphere for 5h to obtain a catalyst. The obtained catalyst product is recorded as DB-2.

[0081] Preparation Comparative Example 3

[0082] This comparative example refers to the preparation method in Preparation Example 1, and the difference from Preparation Example 1 is:

[0083] The beta molecular sieve prepared in step (1) was replaced with a commercially available FAU configuration molecular sieve (the molar ratio of SiO2 / Al2O3 was 4) and used for the catalyst preparation in step (2). The process conditions were the same as those in Preparation Example 1, and the obtained catalyst product was recorded as DB-3.

[0084] Preparation Comparative Example 4

[0085] The catalyst was prepared by referring to the method of Example 1 of CN115869990A and was recorded as DB-4.

[0086] Preparation Example 2

[0087] (1) Sodium aluminate, sodium hydroxide, coarse silica gel, tetraethylammonium hydroxide (TEAOH) and deionized water were added into a beaker at a molar ratio of SiO2 / A12O3=20, H2O / SiO2=8, TEAOH / SiO2=0.1 and NaOH / SiO2=0.1. After stirring at room temperature for 6 hours, the mixture was transferred into a crystallization kettle and crystallized at 120°C for 1 day (24 h). The mixture was then heated to 140°C and crystallized for 2 days (48 h). The crystallization liquid was centrifuged, washed, filtered and dried to obtain beta molecular sieve raw powder (molar ratio of SiO2 / Al2O3 is 18).

[0088] (2) The molecular sieve powder and alumina in step (1) are mixed in a mass ratio of 80:20 (the content of the molecular sieve powder is 80% by weight), and kneaded into a shape. Take 20g of the molded molecular sieve, first roast it at 270°C for 3h in a water vapor atmosphere, with a water flow rate of 0.06ml / g min; then roast it at 400°C for 0.5h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.05mol / L and the flow rate is 0.06ml / g.min; after drying the obtained product, roast it at 450°C for 2.5h in an air atmosphere, and the obtained catalyst product is recorded as Cat-2.

[0089] Preparation Example 3

[0090] (1) Sodium aluminate, sodium hydroxide, coarse silica gel, tetraethylammonium hydroxide (TEAOH) and deionized water were added into a beaker at a molar ratio of SiO2 / A12O3=30, H2O / SiO2=10, TEAOH / SiO2=0.1 and NaOH / SiO2=0.1. After stirring at room temperature for 6 hours, the mixture was transferred into a crystallization kettle and crystallized at 140°C for 2 days (48 hours) and then heated to 160°C for 1 day (24 hours). The crystallization solution was centrifuged, washed, filtered and dried to obtain beta molecular sieve (SiO2 / Al2O3 molar ratio is 29).

[0091] (2) The molecular sieve powder and aluminum sol in step (1) are mixed in a mass ratio of 70:30 (the content of the molecular sieve powder is 70% by weight), and kneaded into a shape. Take 20g of the molded molecular sieve, first roast it at 270°C for 3h in a water vapor atmosphere, with a water flow rate of 0.06ml / g min; then roast it at 400°C for 0.5h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.05mol / L and the flow rate is 0.06ml / g min; after drying the obtained product, roast it at 450°C for 2.5h in an air atmosphere, and the obtained catalyst product is recorded as Cat-3.

[0092] Preparation Example 4

[0093] This preparation example refers to the method in Preparation Example 1, and the difference from Preparation Example 1 is:

[0094] In step (2), 20 g of the formed molecular sieve is first calcined at 300° C. for 3 h in a water vapor atmosphere with a water flow rate of 0.08 ml / g min; then calcined at 450° C. for 0.8 h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.04 mol / L and the flow rate is 0.08 ml / g min; the obtained product is dried and calcined at 450° C. for 2.5 h in an air atmosphere, and the obtained catalyst product is recorded as Cat-4.

[0095] Preparation Example 5

[0096] This preparation example refers to the method in Preparation Example 1, and the difference from Preparation Example 1 is:

[0097] In step (2), 20 g of the formed molecular sieve is first calcined at 200° C. for 1 h in a water vapor atmosphere with a water flow rate of 0.02 ml / g min; then calcined at 500° C. for 0.2 h in an ammonia vapor atmosphere, wherein the ammonia concentration is 0.05 mol / L and the flow rate is 0.02 ml / g min; the obtained product is dried and calcined at 600° C. for 1 h in an air atmosphere, and the obtained catalyst product is recorded as Cat-5.

[0098] Preparation Example 6

[0099] This preparation example refers to the method in Preparation Example 1, and the difference from Preparation Example 1 is:

[0100] In step (1), the raw material mixture is transferred to a crystallization kettle and crystallized at 140° C. for 72 h (one-step crystallization treatment). The remaining process is the same as in Example 1; the obtained catalyst product is recorded as Cat-6.

[0101] The molar ratio of SiO2 / Al2O3, Al / (A 1+ The values ​​of A2)×100%, structural parameters and the B acid content of the catalyst at 350°C are listed in the following Table 1.

[0102] Table 1

[0103]

[0104] Reaction Example

[0105] The products obtained from the above preparation examples, preparation comparative examples and preparation comparative examples are used for concentrated ethylene dry gas (catalytic cracking dry gas or ethane cracking dry gas) and benzene liquid phase alkylation to prepare ethylbenzene, wherein the concentrated ethylene dry gas comprises: ethylene 40.51 volume%, ethane 32.66 volume%, 4.57 volume%, and 22.26 volume%. The reaction conditions include: crushing the catalyst, sieving through 20-40 mesh, loading into a fixed bed catalyst, and reacting with concentrated ethylene dry gas and benzene as raw materials. The reaction conditions are listed in Table 2, and the reaction results of continuous reaction for 24 hours are listed in Table 2.

[0106] Wherein, ethylene conversion rate (%) = (ethylene in feedstock - ethylene in product) / ethylene in feedstock × 100%;

[0107] Selectivity of ethylated product (%) = ethylated product in product / all products × 100%.

[0108] Table 2

[0109]

[0110] According to the data in Tables 1 and 2 above, we can see that:

[0111] Comparing Example 1 with Comparative Example 1, the low silicon-aluminum ratio beta molecular sieve was used in Comparative Example 1. Although the low silicon-aluminum ratio beta molecular sieve has a higher acid content, its crystals are larger and the diffusion path is longer. 10Aromatic hydrocarbons are not easy to desorb and are prone to more side reactions, so the ethylation selectivity is low. The effect of the present disclosure cannot be achieved by simply increasing the amount of beta molecular sieve acid. The molecular sieve provided in Preparation Example 1 has better catalytic performance in the reaction.

[0112] Comparing Preparation Example 1 with Preparation Comparative Example 2, the catalyst obtained by using conventional catalyst preparation process in Preparation Comparative Example 2 has three disadvantages in the alkylation reaction of ethylbenzene by concentrated ethylene dry gas and benzene liquid phase: low ethylene conversion rate, high content of xylene in by-products, and relatively low selectivity of ethylation. The present disclosure provides a method for preparing a catalyst, which can achieve higher raw material conversion and high selectivity and product purity of product ethylbenzene.

[0113] Preparation Example 1 was compared with Preparation Comparative Examples 3 to 4. In Preparation Comparative Example 3, the beta molecular sieve was replaced with a commercially available FAU configuration molecular sieve. Preparation Comparative Example 4 used a catalyst prepared using the prior art. Compared with Preparation Comparative Examples 3 to 4, the catalyst obtained in Preparation Example 1 had higher ethylene conversion rate and ethylation selectivity in the reaction of concentrated ethylene dry gas (catalytic cracking dry gas or ethane cracking dry gas) and benzene liquid phase alkylation to prepare ethylbenzene, and lower xylene content.

[0114] Comparing Preparation Example 1 with Preparation Example 3, it can be seen that the beta molecular sieve of Preparation Example 1 has a SiO2 / Al2O3 molar ratio within a preferred range. Compared with the catalyst of Preparation Example 3, the catalyst obtained in Preparation Example 1 has higher ethylene conversion rate and ethylation selectivity in the reaction of concentrated ethylene dry gas (catalytic cracking dry gas or ethane cracking dry gas) and benzene liquid phase alkylation to prepare ethylbenzene, and lower xylene content.

[0115] Comparing Preparation Examples 1 and 4 with Preparation Example 5, it can be seen that the catalysts prepared in Preparation Examples 1 and 4 are prepared according to the conditions within the preferred range of the present disclosure, and the catalysts obtained in Preparation Examples 1 and 4 have higher ethylene conversion rate and ethylation selectivity in the reaction of concentrated ethylene dry gas and benzene liquid phase alkylation to prepare ethylbenzene, and lower xylene content.

[0116] Comparing Preparation Example 1 with Preparation Example 6, it can be seen that in Preparation Example 1, the molecular sieve is prepared according to the multi-stage crystallization process, and the catalyst obtained in Preparation Example 1 has higher ethylene conversion rate and ethylation selectivity, and lower xylene content.

[0117] Comparing Reaction Examples 1 to 2 with Reaction Examples 8 to 9, it can be seen that under the conditions of using the same catalyst (CAT-1), Reaction Examples 1 to 2 carry out liquid-phase alkylation to produce ethylbenzene according to the reaction conditions within the preferred range provided in the present disclosure, which can achieve higher olefin conversion rate and ethylation selectivity.

[0118] The preferred embodiments of the present disclosure are described in detail above; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0119] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0120] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing ethylbenzene by liquid phase alkylation, characterized in that: The following steps are involved: The raw material dry gas containing ethylene and benzene are contacted with a catalyst to carry out a liquid phase alkylation reaction to obtain a reaction product containing ethylbenzene; The conditions of the liquid phase alkylation reaction include: reaction temperature of 100-300°C, reaction pressure of 1.0-4.0 MPa, benzene / ethylene molar ratio of 2:1-8:1, ethylene weight space velocity of 0.2-2.0 h -1 ; Based on the total weight of the catalyst, the catalyst contains 60 to 90 weight % of a three-dimensional twelve-membered ring molecular sieve and 10 to 40 weight % of an aluminum-containing oxide; the three-dimensional twelve-membered ring molecular sieve includes a BEA structure molecular sieve, and the molar ratio of SiO2 / Al2O3 is 4 to 30.

2. The method according to claim 1, characterized in that The BEA structure molecular sieve is prepared by a method comprising the following steps: S1, mixing a silicon source, an aluminum source, a template, an alkali and water to form a raw material mixture; S2, subjecting the raw material mixture to a first crystallization treatment under a first crystallization condition, and then to a second crystallization treatment under a second crystallization condition; Preferably, in step S1, the silicon source is calculated as SiO2, the aluminum source is calculated as A12O3, the molar ratio of SiO2 / A12O3 in the raw material mixture is 4-60, preferably 6-30, the molar ratio of H2O / SiO2 is 6-60, preferably 8-40, the molar ratio of template / SiO2 is 0.1-0.28, preferably 0.1-0.14, and the molar ratio of NaOH / SiO2 is 0.01-0.2, preferably 0.1-0.

15.

3. The method according to claim 2, characterized in that In step S1, the silicon source is selected from one or more of amorphous silica, silica sol, silica gel, diatomaceous earth and water glass; the aluminum source is selected from one or more of aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride and aluminum oxide; the base is an inorganic base, preferably the base is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide; the template is selected from one or more of tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

4. The method according to claim 2, characterized in that: In step S2, the first crystallization conditions include: temperature of 80-140°C, time of 12-48h, and pressure of autogenous pressure; preferably, temperature of 110-130°C, time of 18-24h; The second crystallization conditions include: temperature of 100-180°C, time of 24-72h, and pressure of autogenous pressure; preferably, temperature of 120-160°C, time of 36-60h; Optionally, after step S2, the method further includes: washing and drying the solid product obtained by the second crystallization treatment.

5. The method according to claim 1, characterized in that The catalyst is prepared by a method comprising the following steps: S3, mixing the three-dimensional twelve-membered ring molecular sieve and the binder, performing a molding process, a first drying process and a first calcination process to obtain a first product; S4, subjecting the first product to a second drying treatment and a second calcination treatment.

6. The method according to claim 5, characterized in that The conditions of the first calcination treatment include: calcination at 200-350°C for 1-4h in a water vapor atmosphere, with a water flow rate of 0.02-0.2ml / gmin; then calcination at 300-500°C for 0.2-1h in an ammonia vapor atmosphere, with an ammonia concentration of 0.01-0.1mol / L and an ammonia flow rate of 0.02-0.2ml / gmin; Preferably, the calcination is carried out at 250-300°C for 2-3h under a water vapor atmosphere, with a water flow rate of 0.04-0.08ml / g min; and then the calcination is carried out at 350-450°C for 0.5-0.8h under an ammonia vapor atmosphere, with an ammonia concentration of 0.02-0.06mol / L and an ammonia flow rate of 0.04-0.15ml / g min; Optionally, the second calcination conditions include: a calcination temperature of 300-600° C., and a calcination time of 1-4 hours. Preferably, the calcination temperature is 400-500° C., and the calcination time is 2-3 hours.

7. The method according to claim 5, characterized in that The binder is selected from one or more of alumina, aluminum sol and pseudo-boehmite; Preferably, based on the total weight of the three-dimensional twelve-membered ring molecular sieve and the binder, the content of the three-dimensional twelve-membered ring molecular sieve is 50 to 90% by weight, preferably 60 to 80% by weight.

8. The method according to claim 1, characterized in that The conditions of the liquid phase alkylation reaction include: reaction temperature of 120-220° C., reaction pressure of 1.0-4.0 MPa, benzene / ethylene molar ratio of 4:1-8:1, ethylene weight space velocity of 0.5-2.0 h -1 ; Optionally, the raw dry gas containing ethylene includes one or more of catalytic cracking dry gas, ethane cracking dry gas, coking dry gas and methanol to olefins crude ethylene gas; preferably, the ethylene concentration in the raw dry gas is above 40 volume %; preferably 50-100 volume %.

9. The method according to claim 1, characterized in that: The BEA structure molecular sieve is a beta molecular sieve; preferably, the molar ratio of SiO2 / Al2O3 of the beta molecular sieve is 6 to 30, preferably 6 to 25; Preferably, the average particle size of the beta molecular sieve is 0.01 to 0.2 μm, preferably 0.04 to 0.1 μm; the BET specific surface area is 400 to 700 m 2 / g, preferably 450 to 650 m 2 / g; total pore volume is 0.4~0.8cm 3 / g, preferably 0.5 to 0.8 cm 3 / g.

10. The method according to claim 1, characterized in that Based on the total weight of the catalyst, the catalyst comprises 60 to 80 weight percent of a three-dimensional twelve-membered ring molecular sieve and 20 to 40 weight percent of an aluminum-containing oxide; Preferably, the aluminum-containing oxide is selected from one or more of aluminum oxide, aluminum sol and aluminum oxide-silicon oxide mixture; preferably aluminum sol and / or aluminum oxide.

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