A process for the preparation of ethylene and propylene

Abstract

The application provides a preparation method of ethylene and propylene, which comprises the following steps: carrying out cracking treatment on n-hexane under the action of a hydrogen type Beta molecular sieve catalyst containing lanthanum at 500-700 DEG C to obtain the ethylene and propylene; and the mass percentage of lanthanum in the hydrogen type Beta molecular sieve catalyst containing lanthanum is 0.7%-1.2%. The application is helpful to improve the yield of ethylene and propylene.

Description

[0001] The present application claims priority to the Chinese patent application No. 202510593058.X, filed on May 08, 2025, and entitled "Preparation method of ethylene and propylene", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of catalytic cracking of hydrocarbons, and in particular to a preparation method of ethylene and propylene. BACKGROUND

[0003] Ethylene, propylene and other olefins are important chemical raw materials, which have a wide range of applications in modern industry. They are the basic raw materials for the synthesis of plastics, rubbers, fibers and other high polymer materials, and play a crucial role in the development of the national economy.

[0004] In traditional chemical production, ethylene is mainly produced by steam cracking of hydrocarbon raw materials such as naphtha. Although this method is widely used in industry, it has some limitations: steam cracking needs to be carried out at high temperature (750-900℃), which has high energy consumption.

[0005] The existing methods for producing ethylene and propylene have the problems of low raw material conversion rate and high energy consumption. SUMMARY

[0006] The present application provides a preparation method of ethylene and propylene, which helps to improve the raw material conversion rate and the yield of ethylene and propylene, and reduce energy consumption.

[0007] The present application provides a preparation method of ethylene and propylene, comprising: under the action of a hydrogen-type Beta molecular sieve catalyst containing lanthanum, cracking treatment of n-hexane at 500-700℃ to obtain the ethylene and propylene; in the hydrogen-type Beta molecular sieve catalyst containing lanthanum, the mass percentage of lanthanum is 0.7%-1.2%.

[0008] Optionally, the method further comprises: 1) dissolving a raw material system comprising an aluminum source and an alkali source in water to obtain a first mixed solution; 2) adding sodium dodecyl benzene sulfonate into the first mixed solution, and then adding white carbon black to obtain a second mixed solution; 3) adding Beta molecular sieve seeds into the second mixed solution, and performing a crystallization reaction at 100-200 DEG C, and after the crystallization reaction is completed, sequentially performing filtration, washing, and drying to obtain a Beta molecular sieve catalyst; 4) performing ammonium ion exchange of the Beta molecular sieve catalyst in an ammonium salt aqueous solution, and then performing washing, drying, and first calcination to obtain a hydrogen-type Beta molecular sieve catalyst; 5) immersing the hydrogen-type Beta molecular sieve catalyst in a lanthanum salt aqueous solution, and then performing drying to obtain a solid powder; performing second calcination of the solid powder, and then placing the solid powder in hydrogen to obtain the hydrogen-type Beta molecular sieve catalyst containing lanthanum.

[0009] Optionally, step 2) further comprises: under the action of ultrasonic waves, adding the sodium dodecyl benzene sulfonate into the first mixed solution, and then adding the white carbon black to obtain the second mixed solution.

[0010] Optionally, in step 4), the number of times of ammonium ion exchange is at least 2.

[0011] Optionally, the aluminum source comprises one or more of sodium metaaluminate, aluminum sol, pseudo-boehmite, and aluminum sulfate.

[0012] Optionally, the alkali source comprises one or more of sodium hydroxide, ammonia water, and potassium hydroxide.

[0013] Optionally, the ammonium salt in the ammonium salt aqueous solution comprises one or more of ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0014] Optionally, the lanthanum salt in the lanthanum salt aqueous solution comprises one or more of lanthanum nitrate, lanthanum sulfate, lanthanum chloride, and lanthanum oxalate.

[0015] Optionally, the mass ratio of the white carbon black to the sodium dodecyl benzene sulfonate is 5:(0.1-0.3).

[0016] Optionally, in step 4), the temperature of the first calcination is 450-550 DEG C.

[0017] The present application provides a preparation method of ethylene and propylene, which utilizes a hydrogen-type Beta molecular sieve catalyst containing lanthanum to catalyze n-hexane cracking, and produces ethylene and propylene, and the raw material conversion rate and the yield of ethylene and propylene are both high, and the energy consumption is low. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 The graph of the type and mass percentage content of the product of Example 1;

[0020] Figure 2 The X-ray diffraction (XRD) graph of the lanthanum-containing hydrogen-type Beta molecular sieve catalyst (La-HBeta molecular sieve) of Example 1. DETAILED DESCRIPTION

[0021] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] In the prior art, the method for producing ethylene and propylene has the problems of low raw material conversion rate and high energy consumption.

[0023] In order to overcome the defects in the prior art, the present application provides a preparation method of ethylene and propylene, comprising: under the action of a lanthanum-containing hydrogen-type Beta molecular sieve catalyst, n-hexane is subjected to cracking treatment at 500-700℃ to obtain ethylene and propylene; in the lanthanum-containing hydrogen-type Beta molecular sieve catalyst (La-HBeta catalyst), the mass percentage content (loading amount) of lanthanum is 0.7%-1.2%.

[0024] According to research and analysis: n-hexane molecules rapidly diffuse in the pore channel of the La-HBeta catalyst → are adsorbed on the Bronsted acid (H acid) and La 3 + cooperative sites → form propylene (main product) and ethylene through β bond rupture → La species inhibits secondary cracking and aromatization side reactions → hydrogen reduces and eliminates carbon deposition and regenerates active sites. This mechanism achieves an optimal balance in the 0.7%-1.2% La loading amount range, realizing nearly 100% conversion rate and high olefin selectivity.

[0025] Exemplarily, the temperature of the above cracking treatment can be 500℃, 550℃, 560℃, 600℃, 650℃, 700℃, or a range formed by any two of them, preferably 550℃-650℃, for example 600℃.

[0026] Exemplarily, the mass percentage of lanthanum (loading) can be 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2% or a range between any two of them.

[0027] Specifically, the above-mentioned hydrogen-type Beta molecular sieve catalyst containing lanthanum and catalyst carrier with a mesh size of 20-40 mesh can be added into a reaction system containing n-hexane in a cracking reactor under an inert protective atmosphere to catalytically crack n-hexane, thereby obtaining ethylene and propylene.

[0028] Understandably, the inert protective atmosphere includes nitrogen, and the flow rate thereof can be 40-60 mL / min, such as 40, 50, 60 mL / min or a range between any two of them.

[0029] In specific implementation, the temperature in the cracking reactor can be equivalent to the temperature of the above-mentioned cracking treatment.

[0030] Understandably, the inert protective atmosphere includes nitrogen, and the flow rate thereof can be 40-60 mL / min, such as 40, 50, 60 mL / min or a range between any two of them.

[0031] The flow rate of n-hexane can be 10-20 mL / h, such as 10, 15, 20 mL / h or a range between any two of them.

[0032] The above-mentioned catalyst carrier includes quartz sand, and the mesh size thereof can be 20-40 mesh.

[0033] In addition, the usage ratio of the above-mentioned hydrogen-type Beta molecular sieve catalyst containing lanthanum and catalyst carrier can be 1:(35-40), such as 1:35, 1:36, 1:40 or a range between any two of them.

[0034] In some embodiments, the lanthanum-containing hydrogen-type Beta molecular sieve catalyst described above can be prepared by a method comprising at least the following processes: 1) dissolving a raw material system comprising an aluminum source and an alkali source in water to obtain a first mixed solution; 2) adding sodium dodecyl benzene sulfonate to the first mixed solution, and then adding white carbon black to obtain a second mixed solution; 3) adding Beta molecular sieve seeds to the second mixed solution, and performing a crystallization reaction at 100-200°C, and after the crystallization reaction is completed, sequentially performing filtration, washing, and drying to obtain a Beta molecular sieve catalyst; 4) performing ammonium ion exchange of the Beta molecular sieve catalyst in an ammonium salt aqueous solution, and then performing washing, drying, and first calcination to obtain a hydrogen-type Beta molecular sieve catalyst; 5) immersing the hydrogen-type Beta molecular sieve catalyst in a lanthanum salt aqueous solution, and then performing drying to obtain a solid powder; and performing second calcination of the solid powder, and then placing the solid powder in hydrogen to perform reduction to obtain the lanthanum-containing hydrogen-type Beta molecular sieve catalyst.

[0035] In step 1), the raw material system comprising the aluminum source and the alkali source is dissolved in water (e.g., deionized water) to obtain a first mixed solution.

[0036] In a specific implementation process, after the raw material system comprising the aluminum source and the alkali source is mixed with the deionized water, stirring can be performed to make the mixed solution clear, that is, to make the raw material system dissolve in the deionized water to obtain the first mixed solution.

[0037] The aluminum source can include one or more of sodium metaaluminate (NaAlO2), aluminum sol, pseudo-boehmite, and aluminum sulfate; and the alkali source can include one or more of sodium hydroxide (NaOH), ammonia, and potassium hydroxide.

[0038] The concentration of the aluminum source in the first mixed solution can be 0.03-0.05 g / mL, such as 0.03 g / mL, 0.04 g / mL, 0.05 g / mL, or a range formed by any two of them.

[0039] The concentration of the alkali source in the first mixed solution can be 0.05-0.10 g / mL, such as 0.05 g / mL, 0.06 g / mL, 0.07 g / mL, 0.08 g / mL, 0.09 g / mL, 0.10 g / mL, or a range formed by any two of them.

[0040] In a specific implementation, 0.7-0.9 g of the aluminum source and 1.3-1.5 g of the alkali source can be dissolved in 18-22 mL of deionized water to obtain the first mixed solution. Exemplarily, the mass of the aluminum source can be 0.7 g, 0.8 g, 0.9 g, or a range formed by any two of them, the mass of the alkali source can be 1.3 g, 1.4 g, 1.5 g, or a range formed by any two of them, and the volume of the deionized water can be 18 mL, 20 mL, 22 mL, or a range formed by any two of them.

[0041] Since the white carbon black is insoluble in water, it is difficult to industrialize the process of preparing molecular sieve by using white carbon black. However, it is found in the research that the hydrophilic treatment of the white carbon black by a suitable method can help to improve the solubility of the white carbon black in water and accelerate the dissolution process, which is helpful to realize the industrialization of the preparation of molecular sieve by using white carbon black.

[0042] Specifically, it is found through research that sodium dodecyl benzene sulfonate is an anionic surfactant, and its molecular structure is composed of an oil-loving alkyl chain (dodecyl) and a water-loving sulfonic acid group. When sodium dodecyl benzene sulfonate is added to water, sodium dodecyl benzene sulfonate molecules (surfactant molecules) will spontaneously form micelles in water under the hydrophilic action of the sulfonic acid group. The inside of the micelles is a hydrophobic core formed by the aggregation of the oil-loving alkyl chains, and the outside of the micelles is composed of the water-loving sulfonic acid group, which can be in contact with water. When white carbon black is added, sodium dodecyl benzene sulfonate molecules will be adsorbed on the surface of white carbon black particles by physical adsorption. Since the surface of white carbon black particles usually has a certain oil-loving property, the oil-loving alkyl chains of sodium dodecyl benzene sulfonate can interact with the surface of white carbon black, while the water-loving sulfonic acid group faces the water phase. Thus, a hydrophilic layer is formed on the surface of the white carbon black particles, and the originally strong oil-loving white carbon black particles are modified to have a certain hydrophilic property, thereby reducing the mutual attraction between the white carbon black particles and reducing the occurrence of agglomeration. When stirring, the white carbon black particles can be better dispersed in water to form a relatively stable dispersion system. That is, by adsorbing on the surface of the white carbon black particles, sodium dodecyl benzene sulfonate increases the surface hydrophilicity of the white carbon black particles, making them easier to disperse in water, which is conducive to the preparation of Beta molecular sieve catalyst with small interfacial tension and good dispersibility.

[0043] Therefore, in step 2), sodium dodecyl benzene sulfonate is added to the first mixed solution, and then white carbon black is added to obtain a second mixed solution.

[0044] The mass ratio of the above-mentioned white carbon black and sodium dodecyl benzene sulfonate can be 5:(0.1-0.3), for example, 5:0.1, 5:0.2, 5:0.3, or a range consisting of any two of them. The dispersibility of the white carbon black in the above preparation system can be better improved, and the interfacial tension and dispersibility of the Beta molecular sieve catalyst can be further improved.

[0045] The above step 2) further comprises: under the action of ultrasonic, sodium dodecyl benzene sulfonate is added to the first mixed solution, and then white carbon black is added to obtain a second mixed solution. The cavitation effect of ultrasonic waves can break the agglomeration of white carbon black, so that it can be better dispersed in water.

[0046] In particular implementation, the first mixed solution can be placed in an ultrasonic stirring device, and stirring and ultrasonic treatment are performed simultaneously, and sodium dodecyl benzene sulfonate is added into the first mixed solution, and after the sodium dodecyl benzene sulfonate is uniformly dispersed in the first mixed solution, white carbon black is added, and then ultrasonic stirring is performed at room temperature (for example, 20-25°C) for 22-26 hours, for example, 22 hours, 24 hours, 26 hours, or a range formed by any two of them, and then a second mixed solution is obtained.

[0047] The white carbon black includes fumed silica.

[0048] In step 3), the Beta molecular sieve seeds are added into the second mixed solution, and a crystallization reaction is performed at 100-200°C, and after the crystallization reaction is completed, filtration, washing, and drying are sequentially performed, and a Beta molecular sieve catalyst is obtained.

[0049] In particular implementation, after the Beta molecular sieve seeds are added into the second mixed solution, stirring can be performed at room temperature for 3-8 minutes, for example, 3 minutes, 5 minutes, 8 minutes, or a range formed by any two of them, and then the mixed solution (mixture) is transferred into a reaction kettle with a polytetrafluoroethylene inner cavity, and a crystallization reaction is performed at 100-200°C, and after the crystallization reaction is completed, filtration, washing, and drying are sequentially performed, and a Beta molecular sieve catalyst is obtained. The Beta molecular sieve catalyst can be used for preparing olefins with 2-4 carbon atoms, such as ethylene, propylene, and butene, from oil cracking, and has the advantages of high raw material conversion rate and low energy consumption, and also has the characteristics of low production cost and simple process flow.

[0050] In some embodiments, the mass ratio of the aluminum source and the Beta molecular sieve seeds can be (2-4):1, for example, 2:1, 3:1, 4:1, or a range formed by any two of them.

[0051] Illustratively, the temperature of the crystallization reaction can be 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, or a range formed by any two of them.

[0052] In addition, the time of the crystallization reaction can be 2-90 hours.

[0053] The operation conditions of the filtration, washing, and drying described above are not particularly limited in the embodiments of the present application, and conventional conditions in the field can be used.

[0054] The Beta molecular sieve seeds described above can be obtained by purchase.

[0055] In step 4), after the Beta molecular sieve catalyst is subjected to ammonium ion exchange in an aqueous ammonium salt solution, washing, drying, and first calcination are performed, and a hydrogen-type Beta molecular sieve catalyst is obtained. The hydrogen-type Beta molecular sieve catalyst has small interfacial tension and good dispersion performance.

[0056] Specifically, the ammonium salt in the ammonium salt aqueous solution includes one or more of ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0057] For example, the ammonium salt aqueous solution includes an ammonium nitrate aqueous solution, which can have a concentration of 0.5, 1, 1.5 mol / L, or a range defined by any two of the foregoing.

[0058] During the ammonium ion exchange, the temperature can be maintained at 70-90°C, for example, 70, 80, 90°C, or a range defined by any two of the foregoing, and the process can be performed under stirring.

[0059] The time for the ammonium ion exchange is not particularly limited in the embodiments of the present application, and can be, for example, 1 h, 2 h, 3 h, 4 h, or a range defined by any two of the foregoing.

[0060] The ammonium ion exchange can be performed at least twice, i.e., the ammonium ion exchange process with the above-mentioned temperature, stirring, and time can be repeated at least twice.

[0061] The washing and drying after the ammonium ion exchange can be performed according to conventional conditions in the art.

[0062] The first calcination can be performed at a temperature of 450-550°C, for example, 450, 500, 550°C, or a range defined by any two of the foregoing, and the first calcination can be performed for a time of 3-5 h, for example, 3, 4, 5 h, or a range defined by any two of the foregoing.

[0063] In step 5), the hydrogen-type Beta molecular sieve catalyst is immersed in a lanthanum salt aqueous solution, and then dried to obtain a solid powder; the solid powder is subjected to second calcination, and then placed in hydrogen to obtain a hydrogen-type Beta molecular sieve catalyst containing lanthanum.

[0064] The hydrogen-type Beta molecular sieve catalyst containing lanthanum has a small interfacial tension and good dispersing performance, and has the advantages of high raw material conversion rate and high conversion rate of alkenes with 2-4 carbon atoms (e.g., ethylene, propylene, butene).

[0065] In some embodiments, the lanthanum salt in the lanthanum salt aqueous solution includes one or more of lanthanum nitrate (e.g., lanthanum nitrate hexahydrate), lanthanum sulfate, lanthanum chloride, and lanthanum oxalate.

[0066] In specific implementations, the lanthanum salt can be added to water, and after stirring and dissolving, the lanthanum salt aqueous solution is obtained.

[0067] The process of immersing the hydrogen-type Beta molecular sieve catalyst in the lanthanum salt aqueous solution can include slowly pouring the lanthanum salt aqueous solution into a container (e.g., a beaker) containing the hydrogen-type Beta molecular sieve catalyst at room temperature.

[0068] In some embodiments, the time for the above impregnation is 8-12h.

[0069] In practice, the above drying process can include: placing the impregnated hydrogen form Beta zeolite catalyst into an oven, drying at 110-130℃, such as 110, 120, 130℃ or a range defined by any two of them, for 6-8h, and the drying process can be stirred 3-4 times.

[0070] The process of second calcination of the solid powder can include placing the solid powder into a crucible, and then placing it into a muffle furnace for second calcination.

[0071] The temperature for the second calcination can be 450-600℃, such as 450, 500, 600℃ or a range defined by any two of them, and the time for the second calcination can be 3-5h, such as 3, 4, 5h or a range defined by any two of them.

[0072] Next, the second calcined zeolite catalyst is placed in hydrogen for reduction, which specifically includes: placing it in a hydrogen gas stream and reducing at 250-350℃, such as 250, 300, 350℃ or a range defined by any two of them, for 2-4h, such as 2, 3, 4h or a range defined by any two of them.

[0073] The application will be further described below through specific examples and comparative examples. Unless otherwise specified, the reagents, materials and instruments used in the following are conventional reagents, conventional materials and conventional instruments, which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthesis methods.

[0074] Beta zeolite seed crystals: purchased from Nankai University Catalyst Factory.

[0075] Example 1

[0076] Preparation of hydrogen form Beta zeolite catalyst containing lanthanum (La-HBeta zeolite):

[0077] Dissolve 0.8g NaAlO2 and 1.4g NaOH in 20ml deionized water, stir until clear, to obtain a first mixed solution (solution A);

[0078] Under ultrasonic treatment and stirring, add 0.1g sodium dodecyl benzene sulfonate to the first mixed solution (solution A), and after uniform ultrasonic stirring, add 5g fumed silica (white carbon black) and ultrasonically stir at room temperature for 24h to obtain a second mixed solution;

[0079] Beta molecular sieve seeds 0.25 g were added to the second mixed solution, which was stirred at room temperature for 5 min, and then transferred to a Teflon-lined autoclave, which was crystallized at 120°C for 90 h. The product after the crystallization reaction was filtered, washed with deionized water, and dried in sequence to obtain a Beta molecular sieve catalyst;

[0080] The above-mentioned Beta molecular sieve catalyst 1.0 g was stirred in 50 mL of an aqueous NH4NO3 solution with a concentration of 1 mol / L at 80°C for 2 h to perform ammonium ion exchange, and then the above-mentioned ammonium ion exchange operation was repeated once. After filtration, washing, and drying, the first calcination was performed at 500°C for 4 h to obtain a hydrogen-type Beta molecular sieve catalyst (HBeta-SDBS molecular sieve).

[0081] La(NO3)3.6H2O 0.14 g was added to 3.5 mL of water to obtain a La(NO3)3 aqueous solution. The above-mentioned hydrogen-type Beta molecular sieve catalyst 5 g was immersed in the above-mentioned La(NO3)3 aqueous solution at room temperature for 10 h, and then the immersed hydrogen-type Beta molecular sieve catalyst was dried at 120°C for 7 h with stirring 4 times during the period to obtain a solid powder. The solid powder was subjected to the second calcination at 500°C for 4 h, and then placed in a hydrogen stream for reduction at 300°C for 3 h to obtain a hydrogen-type Beta molecular sieve catalyst containing lanthanum, and the loading amount (or mass percentage) of lanthanum was 0.9%.

[0082] Preparation of ethylene, propylene, and butene:

[0083] The above-mentioned hydrogen-type Beta molecular sieve catalyst containing lanthanum 0.1 g (20 mesh-40 mesh) and quartz sand 3.6 g (20 mesh-40 mesh) were added to a cracking reactor, which was kept at 600°C, and the flow rate of nitrogen in the reactor was 50 mL / min. Then, n-hexane was introduced (sampled) at a flow rate of 15 mL / h. After 10 min of reaction, the sample was analyzed.

[0084] The conversion rate of n-hexane in Example 1 was 100%, and in the product, the mass percentage of ethylene was 50.5%, the mass percentage of propylene was 14%, the mass percentage of methane was 12%, the mass percentage of ethane was 2%, the mass percentage of propane was 0.5%, the mass percentage of aromatic hydrocarbons was 9%, and the mass percentage of other products was 12%, as shown in Table 1. Figure 1

[0085] The XRD pattern of the hydrogen-type Beta molecular sieve catalyst containing lanthanum (La-HBeta molecular sieve) in Example 1 is shown in FIG. 1. Figure 2 .

[0086] Example 2 ​

[0087] This example is basically the same as example 1, except that:

[0088] The temperature in the cracking reactor is kept at 500°C; other conditions remain unchanged.

[0089] The conversion rate of n-hexane in example 2 is 94%; and in the product, the mass percentage of ethylene is 48.2%, the mass percentage of propylene is 13.5%, the mass percentage of methane is 8%, the mass percentage of ethane is 4.5%, the mass percentage of propane is 2.0%, the mass percentage of aromatic hydrocarbon is 6%, and the mass percentage of other products is 17.8%.

[0090] Example 3

[0091] This example is basically the same as example 1, except that:

[0092] The temperature in the cracking reactor is kept at 700°C; other conditions remain unchanged.

[0093] The conversion rate of n-hexane in example 3 is 99%; and in the product, the mass percentage of ethylene is 47.5%, the mass percentage of propylene is 7.8%, the mass percentage of methane is 23%, the mass percentage of ethane is 2.2%, the mass percentage of propane is 0.3%, the mass percentage of aromatic hydrocarbon is 9.5%, and the mass percentage of other products is 9.7%.

[0094] Example 4

[0095] This example is basically the same as example 1, except that:

[0096] The loading (or mass percentage) of lanthanum in the hydrogen-type Beta molecular sieve catalyst containing lanthanum is 0.7%; other conditions remain unchanged.

[0097] The conversion rate of n-hexane in example 4 is 98%; and in the product, the mass percentage of ethylene is 48.5%, the mass percentage of propylene is 13.5%, the mass percentage of methane is 12%, the mass percentage of ethane is 3%, the mass percentage of propane is 1%, the mass percentage of aromatic hydrocarbon is 8%, and the mass percentage of other products is 14%.

[0098] Example 5

[0099] This example is basically the same as example 1, except that:

[0100] The loading (or mass percentage) of lanthanum in the hydrogen-type Beta molecular sieve catalyst containing lanthanum is 1.2%; other conditions remain unchanged.

[0101] The conversion rate of n-hexane in Example 5 was 97%, and in the product, the mass percentage of ethylene was 49%, the mass percentage of propylene was 11%, the mass percentage of methane was 15%, the mass percentage of ethane was 3%, the mass percentage of propane was 1%, the mass percentage of aromatic hydrocarbon was 9%, and the mass percentage of other products was 12%.

[0102] Comparative Example 1

[0103] Preparation of the hydrogen-type Beta molecular sieve catalyst:

[0104] 0.8g of NaAlO2 and 1.4g of NaOH were dissolved in 20ml of deionized water, and stirred until clear to obtain a first mixed solution (solution A);

[0105] Under ultrasonic treatment and stirring, 0.1g of sodium dodecyl benzene sulfonate was added to the first mixed solution (solution A), and after ultrasonic stirring was uniform, 5g of fumed silica (white carbon black) was added, and ultrasonic stirring was performed at room temperature for 24h to obtain a second mixed solution;

[0106] 0.25g of Beta molecular sieve seeds was added to the second mixed solution, and after stirring at room temperature for 5min, it was transferred to a reaction kettle with a polytetrafluoroethylene inner cavity, and a crystallization reaction was performed at 120℃ for 90h. Then, the product after the crystallization reaction was sequentially filtered, washed with deionized water, and dried to obtain a Beta molecular sieve catalyst;

[0107] 1.0g of the above Beta molecular sieve catalyst was stirred in 50ml of 1mol / L NH4NO3 aqueous solution at 80℃ for 2h to perform ammonium ion exchange, and then the above ammonium ion exchange operation was repeated once. After filtration, washing, and drying, first calcination was performed at 500℃ for 4h to obtain a hydrogen-type Beta molecular sieve catalyst;

[0108] Preparation of ethylene, propylene, and butene:

[0109] 0.1g of the hydrogen-type Beta molecular sieve catalyst (20-40 mesh) and 3.6g of quartz sand (20-40 mesh) were added to a cracking reactor, the cracking reactor was kept at 400℃, and the nitrogen flow rate in the reactor was 50ml / min. Then, n-hexane was introduced at a flow rate of 15ml / h, and after 10min of reaction, sampling and analysis were performed.

[0110] The conversion rate of n-hexane in Comparative Example 1 was 10%, and in the product, the mass percentage of olefins with carbon atom numbers of 2-4 (ethylene, propylene, and butene) was 24%, and the mass percentage of other products was 76%.

[0111] Comparative Example 2

[0112] The present comparative example is basically the same as Comparative Example 1, except that:

[0113] The temperature in the cracking reactor is kept at 500°C; other conditions remain unchanged.

[0114] The conversion rate of n-hexane in Comparative Example 2 is 30%; and in the products, the mass percentage of olefins with carbon atoms of 2-4 (ethylene, propylene, butylene) is 50%, the mass percentage of aromatic hydrocarbons is 5%, and the mass percentage of other products is 45%.

[0115] Comparative Example 3

[0116] The present comparative example is basically the same as Example 1, except that:

[0117] The loading (or mass percentage) of lanthanum in the hydrogen-type Beta molecular sieve catalyst containing lanthanum is 0.6%; other conditions remain unchanged.

[0118] The conversion rate of n-hexane in Comparative Example 3 is 95%; and in the products, the mass percentage of ethylene is 41%, the mass percentage of propylene is 10%, the mass percentage of methane is 15%, the mass percentage of ethane is 5%, the mass percentage of propane is 3%, the mass percentage of aromatic hydrocarbons is 10%, and the mass percentage of other products is 16%.

[0119] Comparative Example 4

[0120] The present comparative example is basically the same as Comparative Example 1, except that:

[0121] The temperature in the cracking reactor is kept at 600°C; other conditions remain unchanged.

[0122] The conversion rate of n-hexane in Comparative Example 4 is 100%; and in the products, the mass percentage of olefins with carbon atoms of 2-4 (ethylene, propylene, butylene) is 39.6%, the mass percentage of aromatic hydrocarbons is 25%, and the mass percentage of other products is 35.4%.

[0123] Comparative Example 5

[0124] The present comparative example is basically the same as Comparative Example 1, except that:

[0125] No ultrasonic treatment process is added; other conditions remain unchanged.

[0126] The conversion rate of n-hexane in Comparative Example 5 is 9%; and in the products, the mass percentage of olefins with carbon atoms of 2-4 (ethylene, propylene, butylene) is 20%, and the mass percentage of other products is 80%.

[0127] Comparative Example 6

[0128] Preparation of H-Beta-TEA molecular sieve:

[0129] Firstly, 1.5 g of NaAlO2 and 0.80 g of NaOH were dissolved in 63 mL of deionized water, stirred until clear, then 97 mL of TEAOH (tetraethylammonium hydroxide) solution was added, and stirred at room temperature for 30 min; then 24 g of hydrophobic type white carbon black was added in batches to promote the dissolution of the white carbon black, and after stirring at room temperature overnight, the mixture was transferred to a polytetrafluoroethylene reaction kettle and crystallized at 140°C for 96 h;

[0130] After the crystallization was completed, the obtained Beta-TEA molecular sieve was centrifuged, washed with deionized water, dried, and finally calcined at 550°C for 5 h in an oxygen atmosphere to eliminate the organic template (tetraethylammonium hydroxide), thereby obtaining a Beta-TEA molecular sieve catalyst;

[0131] 1.0 g of the above Beta molecular sieve was added to 50 mL of an aqueous solution of NH4NO3 with a concentration of 1 mol / L, and stirred at 80°C for 2 h, then the above ion exchange process was repeated once, and then after filtration, washing, and drying, the H-Beta-TEA molecular sieve was obtained by calcining at 450°C for 5 h;

[0132] Preparation of ethylene, propylene, and butene:

[0133] The preparation of ethylene, propylene, and butene in this comparative example was carried out according to the method for preparing ethylene, propylene, and butene in Comparative Example 1, using the H-Beta-TEA molecular sieve described above as the catalyst.

[0134] The conversion rate of n-hexane in Comparative Example 6 was 5%, and the mass percentage of olefins with carbon atoms of 2-4 (ethylene, propylene, and butene) in the product was 26%, and the mass percentage of other products was 74%.

[0135] Comparative Example 7

[0136] This comparative example was basically the same as Comparative Example 2, with the only difference being:

[0137] The H-Beta-TEA molecular sieve of Comparative Example 6 was used to replace the hydrogen-type Beta molecular sieve catalyst of Comparative Example 2; other conditions remained unchanged.

[0138] The conversion rate of n-hexane in Comparative Example 7 was 20%, and the mass percentage of olefins with carbon atoms of 2-4 (ethylene, propylene, and butene) in the product was 35%, the mass percentage of aromatic hydrocarbons was 2.2%, and the mass percentage of other products was 62.8%.

[0139] Comparative Example 8

[0140] This comparative example is basically the same as Comparative Example 3, except that:

[0141] The H-Beta-TEA molecular sieve of Comparative Example 6 is used to replace the hydrogen-type Beta molecular sieve catalyst of Comparative Example 3; other conditions remain unchanged.

[0142] The conversion rate of n-hexane of Comparative Example 8 is 90%; and in the product, the mass percentage content of olefins with carbon atom number of 2-4 (ethylene, propylene, butene) is 46%, the mass percentage content of aromatic hydrocarbon is 21%, and the mass percentage content of other products is 33%.

[0143] Comparative Example 9

[0144] This comparative example is basically the same as Comparative Example 4, except that:

[0145] The H-Beta-TEA molecular sieve of Comparative Example 6 is used to replace the hydrogen-type Beta molecular sieve catalyst of Comparative Example 4; other conditions remain unchanged.

[0146] The conversion rate of n-hexane of Comparative Example 9 is 100%; and in the product, the mass percentage content of olefins with carbon atom number of 2-4 (ethylene, propylene, butene) is 37.5%, the mass percentage content of aromatic hydrocarbon is 34%, and the mass percentage content of other products is 28.5%.

[0147] Comparative Example 10

[0148] This comparative example is basically the same as Comparative Example 1, except that:

[0149] No sodium dodecyl benzene sulfonate is added, and other conditions remain unchanged.

[0150] The conversion rate of n-hexane of Comparative Example 10 is 8%; and in the product, the mass percentage content of olefins with carbon atom number of 2-4 (ethylene, propylene, butene) is 18%, and the mass percentage content of other products is 82%.

[0151] Comparative Example 11

[0152] Preparation of a Beta molecular sieve catalyst containing lanthanum:

[0153] 0.8g NaAlO2, 1.4g NaOH were dissolved in 20ml deionized water, stirred until clear, to obtain a first mixed solution (solution A);

[0154] Under ultrasonic treatment and stirring, 0.1g sodium dodecyl benzene sulfonate was added to the first mixed solution (solution A), and after ultrasonic stirring was uniform; then 5g fumed silica (white carbon black) was added, and ultrasonic stirring was carried out at room temperature for 24h, to obtain a second mixed solution;

[0155] Beta molecular sieve seeds 0.25 g were added to the second mixed solution, stirred at room temperature for 5 min, and then transferred to a Teflon-lined autoclave for crystallization at 120°C for 90 h. The product after the crystallization reaction was sequentially filtered, washed with deionized water, and dried to obtain a Beta molecular sieve catalyst;

[0156] La(NO3)3.6H2O 0.14 g was added to 3.5 mL of water and stirred to dissolve, obtaining a La(NO3)3 aqueous solution. 5 g of the above Beta molecular sieve catalyst was immersed in the La(NO3)3 aqueous solution at room temperature for 10 h, and then the immersed Beta molecular sieve catalyst was dried at 120°C for 7 h with stirring 4 times during the period, obtaining a solid powder. The solid powder was subjected to a second calcination at 500°C for 4 h, and then placed in a hydrogen stream for reduction at 300°C for 3 h, obtaining a Beta molecular sieve catalyst containing lanthanum (0.9% La-Beta molecular sieve), and the loading (or mass percentage) of lanthanum was 0.9%.

[0157] Preparation of ethylene, propylene, and butene:

[0158] 0.1 g of the Beta molecular sieve catalyst containing lanthanum (0.9% La-Beta molecular sieve) (20-40 mesh) and 3.6 g of quartz sand (20-40 mesh) were added to a cracking reactor, the cracking reactor was kept at 400°C, and the nitrogen flow in the reactor was 50 mL / min. Then, n-hexane was introduced at a flow rate of 15 mL / h. After 10 min of reaction, the sample was analyzed.

[0159] The conversion rate of n-hexane in Comparative Example 11 was 53%, and the mass percentage of olefins with carbon atoms 2-4 (ethylene, propylene, and butene) in the product was 31%, the mass percentage of aromatic hydrocarbons was 10%, and the mass percentage of other products was 59%.

[0160] Comparative Example 12

[0161] Preparation of a Beta molecular sieve catalyst containing lanthanum (La-Beta molecular sieve):

[0162] This comparative example is basically the same as Comparative Example 11, except that:

[0163] No sodium dodecyl benzene sulfonate was added, and other conditions remained unchanged.

[0164] The conversion rate of n-hexane in Comparative Example 12 was 32%, and the mass percentage of olefins with carbon atoms 2-4 (ethylene, propylene, and butene) in the product was 18%, the mass percentage of aromatic hydrocarbons was 8%, and the mass percentage of other products was 74%.

[0165] Comparative Example 13

[0166] This comparative example is substantially the same as Example 1, except that:

[0167] The loading (or mass percentage) of lanthanum in the hydrogen-type Beta molecular sieve catalyst containing lanthanum is 1.3%; other conditions remain unchanged.

[0168] The conversion rate of n-hexane in Comparative Example 13 is 92%; and in the products, the mass percentage of ethylene is 40%, the mass percentage of propylene is 9%, the mass percentage of methane is 18%, the mass percentage of ethane is 6%, the mass percentage of propane is 4%, the mass percentage of aromatic hydrocarbon is 12%, and the mass percentage of other products is 11%.

[0169] Comparative Example 14

[0170] Preparation of H-ZSM-5 molecular sieve catalyst containing lanthanum (La-HZSM-5):

[0171] Step 1: 1.0 g of commercial ZSM-5 molecular sieve (SiO2 / Al2O3molar ratio = 80) was subjected to ammonium ion exchange in 50 mL of 1 mol / L NH4NO3 aqueous solution at 80°C for 2 h, and then the above ammonium ion exchange operation was repeated once. After filtration, washing, and drying, the first calcination was performed at 500°C for 4 h to obtain a hydrogen-type ZSM-5 molecular sieve catalyst;

[0172] Step 2: 0.14 g of lanthanum nitrate hexahydrate was added to 3.5 mL of water to obtain a lanthanum nitrate aqueous solution; 5 g of the above hydrogen-type ZSM-5 molecular sieve catalyst was immersed in the above lanthanum nitrate aqueous solution at room temperature for 10 h, and then the immersed hydrogen-type ZSM-5 molecular sieve catalyst was dried at 120°C for 7 h with stirring 4 times during the period to obtain a solid powder; the solid powder was subjected to second calcination at 500°C for 4 h, and then was placed in a hydrogen stream for reduction at 300°C for 3 h to obtain a hydrogen-type ZSM-5 molecular sieve catalyst containing lanthanum, and the loading (or mass percentage) of lanthanum was 0.9%;

[0173] The reaction conditions for preparing ethylene, propylene, and butene were the same as those in Example 1 (the temperature was 600°C).

[0174] The conversion rate of n-hexane in Comparative Example 14 is 85%; in the products, the mass percentage of ethylene is 38%, the mass percentage of propylene is 9%, the mass percentage of methane is 16%, the mass percentage of ethane is 4%, the mass percentage of propane is 2%, the mass percentage of aromatic hydrocarbon is 13%, and the mass percentage of other products is 18%.

[0175] Comparative Example 15:

[0176] La-HY catalyst was prepared by loading La onto H-Y catalyst:

[0177] 1.0 g of a commercial Y-type molecular sieve with a Na content of less than 0.1% was converted into HY by NH4 + exchange (as in Step 1 of Comparative Example 14) to form HY;

[0178] La-HY catalyst was prepared by loading La onto H-Y catalyst as in Step 2 of Comparative Example 14, and the loading amount (or mass percentage) of La was 0.9%.

[0179] The reaction conditions for preparing ethylene, propylene and butylene were the same as in Example 1 (temperature was 600°C).

[0180] The conversion rate of n-hexane in Comparative Example 15 was 78%; in the products, the mass percentage of ethylene was 32%, the mass percentage of propylene was 7%, the mass percentage of methane was 14%, the mass percentage of ethane was 5%, the mass percentage of propane was 3%, the mass percentage of aromatic hydrocarbons was 15%, and the mass percentage of other products was 24%.

[0181] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that they can still modify the technical solutions described in the above examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of ethylene and propylene, characterized in that, The application relates to a method for preparing ethylene and propylene. The content of lanthanum in the hydrogen-type Beta molecular sieve catalyst containing lanthanum is 0.7%-1.2% by mass. The method further comprises: 1) dissolving a raw material system comprising an aluminum source and an alkali source in water to obtain a first mixed solution; 2) adding sodium dodecyl benzene sulfonate into the first mixed solution, and then adding white carbon black to obtain a second mixed solution; 3) adding Beta molecular sieve seeds into the second mixed solution, and performing a crystallization reaction at 100-200 DEG C; after the crystallization reaction is completed, performing filtration, washing and drying in sequence to obtain a Beta molecular sieve catalyst; 4) performing ammonium ion exchange of the Beta molecular sieve catalyst in an ammonium salt aqueous solution, and then performing washing, drying and first calcination to obtain a hydrogen-type Beta molecular sieve catalyst; 5) immersing the hydrogen-type Beta molecular sieve catalyst in a lanthanum salt aqueous solution, and then performing drying to obtain a solid powder; after the solid powder is subjected to second calcination, it is placed in hydrogen to be reduced to obtain the hydrogen-type Beta molecular sieve catalyst containing lanthanum. Step 2) further comprises:

2. The production method according to claim 1, characterized by, Under the action of ultrasonic waves, the sodium dodecyl benzene sulfonate is added into the first mixed solution, and then the white carbon black is added to obtain the second mixed solution. In step 4), the number of times of ammonium ion exchange is at least 2.

3. The preparation method according to claim 1, characterized in that, The aluminum source comprises one or more of sodium metaaluminate, aluminum sol, pseudo-boehmite and aluminum sulfate.

4. The method of claim 1, wherein, The alkali source comprises one or more of sodium hydroxide, ammonia water and potassium hydroxide.

5. The preparation method according to claim 1, characterized in that, The ammonium salt in the ammonium salt aqueous solution comprises one or more of ammonium nitrate, ammonium chloride and ammonium sulfate.

6. The method of claim 1, wherein, The lanthanum salt in the lanthanum salt aqueous solution comprises one or more of lanthanum nitrate, lanthanum sulfate, lanthanum chloride and lanthanum oxalate.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the white carbon black to the sodium dodecyl benzene sulfonate is 5: (0.1-0.3).

8. The method of claim 1, wherein, In step 4), the temperature of the first calcination is 450-550 DEG C.

9. The method of claim 1, wherein, ​

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