KR102052437B1 - Method for selective ethylene production from propylene - Google Patents

Abstract

Provided is a process for preparing selective ethylene from propylene of the present invention, more specifically ZSM-5 catalyst with controlled Si / Al ₂ molar ratio and ethylene from propylene to produce ethylene with high selectivity from propylene in a controlled process. It provides a method of manufacturing.

Description

Method for selective ethylene production from propylene

The present invention relates to a process for producing ethylene selectively from propylene, and more particularly to a process for producing ethylene with high selectivity from propylene under certain zeolite catalysts and under certain conditions.

Light olefins, ethylene and propylene, are currently the main bulk chemicals in the petrochemical market and are important raw materials used in the manufacture of various chemicals such as plastics, synthetic rubber, packaging, textiles, building materials, furniture, and the like. Because of these diverse applications, the use of ethylene and propylene in the global market is expected to continue to increase in the future.

Particularly in the case of ethylene, more than 50% of ethylene is used in the production of polyethylene and ethylene copolymers worldwide, and in addition, various kinds called oxidization, hydrogenation, hydrogen halide, alkylation, hydration, oligomerization, hydroformylation, etc. Through chemical reactions, it is very important for chemical industry and is supplied with various raw compounds.

In the petrochemical industry, there are various routes to produce these light olefins, but steam for producing olefins by pyrolysing hydrocarbon raw materials such as gaseous raw materials (ethane, propane) and liquid raw materials (naphtha, gas oil) at high temperature with water vapor Cracking process is the most commonly used process. The yield of the product obtained through this steam cracking is largely determined according to the hydrocarbon raw materials used. In the case of ethane crackers using ethane as a raw material, ethylene is mainly produced (about 83% yield), and a little fuel oil is produced. Obtained as a byproduct.

However, naphtha crackers, which currently account for the largest number of crackers operating in the world for olefin production, can obtain C4 fraction, BTX aromatic fraction and other fuels as light by-products of ethylene and propylene, which are light olefins, where ethylene 32% It has a yield of about 16% propylene.

Although the amount of ethylene produced in the petroleum-derived naphtha cracking process, which is the most olefin-making process, is about 2 times higher than that of propylene production, the type of hydrocarbon raw materials used and the process applied differ from region to region. Due to the different kinds of industries that use light olefins to produce chemicals, the price gap between ethylene and propylene is inevitably caused by regional demand and supply, such as the United States, Europe, China, and Asia.

Therefore, the development of olefin interconversion technology is needed to balance this regional demand for light olefins supply-demand between ethylene and propylene.

In this olefin interconversion study, the propylene production process (Ethylene-to-Propylene, ETP) has been extensively studied from ethylene due to the expectation that the price and demand of propylene will be relatively higher than that of ethylene.

In recent years, however, many new ethane crackers have been supplied in the United States to use shale gas, a gaseous feedstock in the United States, but in Asia, as well as high ethylene demand, there are many, many such as naphtha crackers, PDH and MTP. Due to the availability of propylene sources, propylene is relatively cheaper than ethylene.

Therefore, there is a need to develop a process for selectively converting propylene to ethylene (Propylene-to-Ethylene, PTE) in Asia.

 In the 1960s, a triolefin process using olefin metathesis reaction was developed and commercialized as PTE related technology. This metathesis reaction uses a heterogeneous catalyst in which tungsten oxide is supported on a silica support, and theoretically converts 2 moles of propylene into one ethylene and 2-butene, respectively.

However, in order to maximize the ethylene yield in the process using metathesis reaction, since the ethylene one-pass selectivity is less than 35.3% in propylene self-metathesis reaction, the selectivity of ethylene is not high. The metathesis reactors of the raw material propylene and the main by-product butene and the reactors which decompose variously produced hydrocarbons must be composed essentially in series. Commercialization of selective ethylene production from propylene via metathesis routes has been discontinued for reasons such as such.

 Zeolites, on the other hand, have been used as solid acid catalysts in many catalytic processes in the chemical industry because of their unique shape selectivity and adjustable acid point. In particular, these features have led to high efficiencies in oil refinery and petrochemical processes. For example, zeolite catalysts exhibit high catalytic activity and production selectivity in a series of catalytic reactions such as cracking, isomerization, aromatization, disproportionation, alkylation. Zeolites as catalysts in ethylene production have mostly been used as additional processes in the overall process for improving the yield of light olefins, and ethylene is obtained through catalytic cracking of the reaction intermediates olefins and hydrocarbons. Ethylene selectivity was reported as low as 12-30% in this catalyst cracking.

Therefore, there are limitations in applying existing technologies and catalysts to produce selective ethylene from propylene, and new processes are needed to improve this.

International Publication No. WO2005-014169

The present invention provides a process for the selective production of ethylene from propylene, the process of producing ethylene using the metathesis of conventional commercialized propylene and the process of producing ethylene as a byproduct in olefin and hydrocarbon material cracking reactions. From ethylene with high selectivity.

In order to achieve the above object, the present invention provides a method for selectively producing ethylene from propylene under specific catalysts and controlled specific process conditions, the method for selectively producing ethylene from propylene of the present invention,

Preparing ethylene by reacting propylene under a ZSM-5 catalyst having a Si / Al ₂ molar ratio of 23 to 280.

Preferably the Si / Al ₂ molar ratio according to an embodiment of the present invention may be 30 to 100.

Preferably, the ZSM-5 catalyst of the present invention may be 0.5 to 5% by weight of phosphorus supported, phosphorus supported on the ZSM-5 catalyst is phosphoric acid (H ₃ PO ₄ ), the first ammonium phosphate salt ((NH ₄ ) One or more than one selected from H ₂ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), (C1-C10) alkyl phosphite and (C1-C10) alkyl phosphate It may be derived from a phosphorus compound.

The reaction for selectively producing ethylene from propylene according to an embodiment of the present invention is preferably performed at a temperature of 550 to 600 ° C., a pressure of 1 to 10 KPa, and a pressure of 0.1 to 10 hours ⁻¹ in terms of increasing the selectivity of ethylene. Weight hourly space velocity and a propylene and nitrogen dilution ratio of 1: 1 to 1:30.

ZSM-5 catalyst according to an embodiment of the present invention may be treated with 10 to 25 ml of the silylating agent based on 100 g of the ZSM-5 catalyst, the silylating agent is Si (R ¹ ) _{4 - n} (OR ² ) _It may be one or two or more selected from _n (where R ¹ and R ² are independently of each other (C1-C10) alkyl, n is an integer from 1 to 4).

Preferably ZSM-5 catalyst according to an embodiment of the present invention may be H-ZSM-5, La, Zn, Ni, Fe, Ga, Cu, Pd, Al, Co, M, Ce, Cr, Au, One or more selected from Pt, Re, Ru, and Ir may be supported.

Preferably the step of selectively producing ethylene from the propylene of the present invention may be carried out in a fixed bed reactor or a fluidized bed reactor, the conversion of propylene is at least 50%, the selectivity of ethylene may be at least 40%.

The process for the selective production of ethylene from propylene of the present invention is very selective in the selectivity of ethylene produced by using a ZSM-5 catalyst, a specific catalyst having a controlled Si / Al ₂ molar ratio, and reacting propylene under controlled specific reaction conditions. high.

Therefore, due to the recent low oil prices in the Asia-Pacific region, the use rate of naphtha crackers is high, and propylene is produced in large quantities in response to demand, and PDH and petroleum substitute, on-purpose processes for producing propylene from cheap natural gas (mostly propane) Alternatively, the MTP process using methanol, a non-petroleum-based raw material, has been newly constructed and operated to produce excessive propylene compared to local demand. Thus, the method for producing ethylene from the propylene of the present invention selects high-priced ethylene from low-cost propylene. It can produce economically, and it has an effect that can economically resolve the imbalance of demand-supply of ethylene-propylene.

1 is a graph showing the conversion of propylene and the yield of ethylene of Example 1 and Comparative Example 1 of the present invention.
2 is a graph showing the acidity and selectivity of ethylene, the Si / Al2 molar ratio and the conversion rate of propylene in Example 2 and Comparative Example 2 of the present invention.
3 to 4 are graphs showing the conversion rate of propylene and the selectivity of ethylene according to Example 3 of the present invention.
5 is a graph showing the conversion rate of propylene and the selectivity of ethylene according to Example 4 of the present invention.
6 is a graph showing the conversion rate of propylene and the selectivity of ethylene according to Example 5 of the present invention.
7 is a graph showing the conversion rate of propylene and the selectivity of ethylene according to Example 6 of the present invention.

The present invention provides a process for producing ethylene with high selectivity from propylene under specific catalysts and controlled specific process conditions.

Ethylene is prepared by contacting propylene with a ZSM-5 catalyst having a Si / Al ₂ molar ratio of 23 to 280.

The process for producing selective ethylene from propylene of the present invention can produce ethylene with high selectivity by contacting propylene under a specific catalyst having controlled conditions, and is not a preparation of olefins obtained from various by-products by pyrolysis of conventional olefins. It is a method to obtain ethylene with high selectivity from propylene.

Furthermore, the process for producing selective ethylene from propylene of the present invention can selectively obtain ethylene under specific catalysts and controlled specific process conditions.

In addition, the process for producing selective ethylene from propylene of the present invention is very economical because it is possible to obtain ethylene with surprisingly improved selectivity and simple process, unlike the conventional method, propylene is not a method for producing propylene from ethylene which is already known in various ways The supply imbalance of ethylene and propylene can be eliminated by providing a process for the selective production of ethylene from ethylene.

The specific catalyst used for the selective ethylene from propylene of the present invention is ZSM-5, unlike ZSM-11, ZSM-22, HY, SSZ-13, SAPO-34, SAPO-11, mordenite and beta, which are common zeolite catalysts. The conversion and selectivity of ethylene are surprisingly improved.

Preferably, the Si / Al ₂ molar ratio of ZSM-5 may be 23 to 280, and the strong acid point by the bridged Si-O-Al in the ZSM-5 catalyst is increased, resulting in excessive hydrocarbon cracking reaction or oligomer of olefin. Silica and neighboring aluminum in ZSM-5 are also used in terms of reducing the formation of by-products through polymerization and aromatization, and in order not to reduce the catalyst life due to coke deposition in the ZSM-5 catalyst pores and to reduce thermal and hydrothermal stability. In order to increase the conversion of propylene and the selectivity of ethylene by increasing the number of small ZSM-5 strong acid points generated due to the small number, the Si / Al ₂ mole ratio of ZSM-5 is preferably 30 to 100 days. Can be.

In terms of increasing the selectivity of ethylene, controlled reactions include temperatures of 550-600 ° C., atmospheric pressure of 1-10 KPa, hourly space velocity of propylene of 0.1-10 hours ⁻¹ and propylene and nitrogen of 1: 1-1: 30. It may be performed at the dilution ratio (volume ratio).

The combination of ZSM-5, which is a specific catalyst that satisfies a specific range of reaction conditions and specific conditions controlled as described above, greatly improves ethylene selectivity.

Preferably, the ZSM-5 catalyst of the present invention may be a catalyst supported by 0.5 to 5% by weight of phosphorus, and more preferably, a ZSM-5 catalyst supported by 0.75 to 1.5% by weight.

In general, zeolites can be deactivated in two aspects in solid acid catalysis. The first is when the reactants or products are deactivated by reacting at acid points to produce coke. It is possible to regenerate the catalyst by burning the coke. The second case is when aluminum, which acts as a scattering point in the zeolite, escapes out of the zeolite framework and weakens the acidic point so that deactivation occurs. The second case generally occurs irreversibly and especially well at moist conditions at high temperatures. Since this is an irreversible process, it is difficult to regenerate the catalyst, so it is necessary to prevent dealumination in the zeolite.

Therefore, in the present invention, to prevent such dealumination, the ZSM-5 catalyst may be modified with phosphorus.

In the ZSM-5 catalyst according to the present invention, the acid point is modified to phosphorus (P), which increases the hydrothermal stability of the aluminum in the skeleton, and weakens the strong acid point, thus making it possible to produce a part of the mid-century acid point.

Therefore, in the present invention, the ZSM-5 catalyst preferably controls the amount of phosphorus (P) to be treated, and 0.5 to 5% by weight of phosphorus (P) by weight based on the total amount of the ZSM-5 catalyst. ) May be contained. It prevents the decrease of hydrothermal stability of ZSM-5 catalyst and the number of strong acid points of ZSM-5 catalyst which is neutralized by phosphorus increases the initial acid strength of catalyst so that the selectivity of ethylene is not reduced by catalytic cracking of mixed raw materials. It is more desirable to solve the problem that the phosphoric acid neutralizes excessively strong phosphorus to deactivate the catalyst, and also the pores of the ZSM-5 catalyst due to phosphorus are blocked, and the specific surface area of the catalyst is greatly reduced to reduce the catalytic activity. Preferably, 0.75 to 1.5% by weight of phosphorus may be supported.

The phosphorus supported on the ZSM-5 catalyst of the present invention is phosphoric acid (H 3 PO 4), monobasic ammonium phosphate ((NH 4) H 2 PO 4), diammonium phosphate salt ((NH 4) 2 HPO 4), (C 1 -C 10) alkyl phosphorous acid (alkyl phosphite) And (C1-C10) alkyl phosphate, any one or two or more phosphorus compounds may be used, and in terms of increasing the selectivity of ethylene, preferably phosphoric acid (H 3 PO 4), a first ammonium phosphate ((NH 4) ) H 2 PO 4) and diammonium phosphate salt ((NH 4) 2 HPO 4) may be derived from a phosphorus compound selected from phosphoric acid compounds.

Alkyl as described herein includes both straight and branched chains, meaning a hydrocarbon radical of 1 to 10 carbon atoms, preferably a hydrocarbon radical of 1 to 5 carbon atoms.

When the phosphate compound is impregnated with the ZSM-5 catalyst, the position at which phosphorus (P) is impregnated little by little depending on the type of phosphorus compound, but in general, the particle size of the phosphate compound is relatively higher than the pore size of the crystalline zeolite. Because of its size, the infiltration and impregnation of the phosphorus compound into the pores of the crystalline zeolite is less than that of the outer surface of the zeolite, so that a relatively large amount of phosphorus (P) is present on the outer surface of the zeolite catalyst.

In the cracking reaction to decompose propylene, Brenstead acid point, which is the strong acid point of ZSM-5 catalyst, is used, and it is assumed that both the outer surface and the inner pore surface of the catalyst exist, and if the reaction occurs at the active point of the outer surface, ZSM- 5 It has been a factor to inhibit the shape selectivity of the catalyst, and to reduce the selectivity of the ethylene produced.

Therefore, it is determined that ethylene is produced with high selectivity by removing the external acidic point, which is the external catalyst active point, so that the reaction occurs only at the internal acidic point of the ZSM-5 catalyst.

That is, in the case of the ZSM-5 catalyst modified by impregnating phosphoric acid, the external acid point is appropriately inactivated, and the reaction mainly occurs at the acid point in the pores of the ZSM-5 catalyst, thereby increasing the selectivity of ethylene.

The method of impregnating a phosphorus compound according to an embodiment of the present invention on a ZSM-5 catalyst may be any conventional impregnation method. Specific examples include ion-exchange method, incipient wetness method, and solution. Both impregnation methods are applicable.

Reaction conditions for selectively producing ethylene from propylene according to an embodiment of the present invention preferably in terms of increasing the selectivity of ethylene, a temperature of 550 to 600 ℃, atmospheric pressure of 1 to 10 KPa, 0.1 to 10 hours ^-1 propylene Propylene and nitrogen dilution ratio (volume ratio) of 1: 1 to 1:30 and the hourly weight space velocity of, more preferably a temperature of 500 to 550 ℃, atmospheric pressure of 1 to 5 KPa, 1 to 2 hours ^-1 propylene The weight hourly space velocity of and propylene and nitrogen dilution ratio (volume ratio) of 1: 4 to 1: 16.5.

In the process for producing selective ethylene from propylene of the present invention, the outer surface may be modified by treating the ZSM-5 catalyst with a silylating agent to further improve the selectivity of ethylene. In this case, as the silylating agent that can be used, Si (R ¹ ) _4-n (OR ² ) _n (wherein R ¹ and R ² are independently of each other (C 1 -C 10) alkyl and n is an integer of 1 to 4). It may be one or two or more selected from, specifically, all 1 to 4 quaternary alkoxysilane is applicable, and specifically, quaternary alkoxysilane, tetramethoxysilane, tetraethoxysilane or tertiary alkoxysilane Trimethoxymethylsilane, trimethoxyethylsilane.

Particularly in the case of quaternary alkoxysilanes, four silanol groups are present to form a new bond with the reactive active site of the aluminosilicate outer surface of the ZSM-5 catalyst, thereby increasing the proportion of Si atoms present on the outer surface. It is more preferable because the reaction active point of the surface can be eliminated to cause the reaction in the pores to increase the selectivity of ethylene.

Specifically, the ZSM-5 catalyst according to an embodiment of the present invention may be treated with 10 to 25 ml of silylating agent based on 100 g of ZSM-5 catalyst, and the silylating agent may be tetramethoxysilane, tetraethoxysilane, It may be one or two or more selected from trimethoxymethylsilane and trimethoxyethylsilane.

Preferably ZSM-5 catalyst according to an embodiment of the present invention may be H-ZSM-5, La, Zn, Ni, Fe, Ga, Cu, Pd, Al, Co, M, Ce, Cr, Au, One or more selected from Pt, Re, Ru, and Ir may be supported.

Preferably, the step of selectively preparing ethylene from the propylene of the present invention may be carried out in a fixed bed reactor or an induction bed reactor as long as it is within the range recognized by those skilled in the art.

In the method for preparing selective ethylene from propylene of the present invention, the conversion rate of propylene may be 50% or more, the selectivity of ethylene may be 40% or more, preferably the conversion rate of propylene is 60%, and the selectivity of ethylene may be 70%. .

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to examples, but these examples are merely illustrative of the present invention, and the scope of the present invention is not limited only to these examples.

Preparation Example 1 Preparation of Catalyst Used in the Present Invention

SAPO-34, ZSM-11 and ZSM-22 (Journal of Nanoscience and Nanotechnology, 13 (2013) 2782-2788. Journal of the Chemical Society, Faraday Transactions, 87 (1991) 3709-3716. Catalysis Today 179 (2012) 61-72), and other commercialized products such as ZSM-5, ZSM-35 (Zeolist) and SSZ-13 (China holding company) were used.

Preparation Example 2 Preparation of ZSM-5 Catalyst Supported with Phosphorus

3 g of ZSM-5 zeolite was uniformly mixed with an aqueous solution mixed with 0.43 g of phosphoric acid (H ₃ PO ₄ , 85%), 1.789 g of ethanol, and 0.24 g of distilled water, and then the solvent was removed using a dry oven to support phosphoric acid. The sample prepared above was calcined at 500 ° C. for 5 hours to prepare a ZSM-5 catalyst having 1% by weight of phosphorus and used in this experiment.

By varying the molar ratio of zeolite and phosphoric acid, a ZSM-5 catalyst was prepared in which 0.5% by weight, 0.75% by weight, 1.25% by weight and 1.5% by weight of phosphorus were supported, respectively.

Preparation Example 3 Preparation of Silyzed ZSM-5 Catalyst

2 g of ZSM-5 and 50 ml of hexane were mixed, refluxed at 70 ° C. for 30 minutes, cooled to room temperature, and injected into 0.3 ml of TEOS (tetraethoxysilane), and then refluxed at 70 ° C. for 1 hour. The reaction mixture was cooled, washed with ethanol, dried for 2 hours using a dry oven, and then calcined at 500 ° C. for 4 hours and then applied to the experiment.

The silylated ZSM-5 was prepared in the same manner as above except that TMOS (tetramethoxysilane), TPOS (tetrapropoxysilane), and TBOS (tetrabutoxysilane) were used instead of TEOS as the silylating agent. Was prepared.

Example 1 and Comparative Example 1 Preparation of Ethylene from Propylene under Each Catalyst

After filling 0.5 g each of the ZSM-5 catalyst prepared in Preparation Example 1 of the present invention and each zeolite of FIG. 1 into a 0.5 inch fixed bed reactor, propylene was injected into the fixed bed reactor, but the reaction temperature of 550 ° C. was 0.1 Ethylene was prepared by the reaction under the conditions of MPa and a weight space velocity (WHSV) of 1.09 h ^{- 1} , a partial pressure of propylene of 0.0065 MPa, and a total flow rate of 70.6 ml / min. The yield is shown in FIG.

As shown in FIG. 1, it can be seen that the ZSM-5 catalyst of the present invention has a high conversion rate of propylene and a high yield of ethylene (catalyst of Comparative Example 1: catalysts other than ZSM-5 are all catalysts of Comparative Example 1). ).

Example 2 Preparation of Ethylene from Propylene According to Si / Al ₂ Molar Ratio

A ZSM-5 catalyst was used as a catalyst in Example 1, except that a ZSM-5 catalyst having a Si / Al ₂ molar ratio as described in Table 1 was used. 2 is shown.

As shown in Table 1 and Figure 2 it can be seen that the selectivity and yield of ethylene is significantly different depending on the Si / Al ₂ molar ratio.

Example 3 Preparation of Ethylene from Propylene under PSM Supported ZSM-5 Catalyst

Ethylene was prepared from propylene in the same manner as in Example 1 using the ZSM-5 catalyst and the ZSM-5 catalyst supported on phosphorus prepared in Preparation Example 2, and the acid point of ZSM-5 supported on phosphorus in Table 2 below. 3 shows the conversion of propylene and the selectivity of ethylene.

As shown in Table 2 and FIGS. 3 to 4, phosphorus-supported ZSM-5 has a controlled acid point to increase the selectivity of ethylene, and ZSM-5 having this controlled acid point has better conversion of propylene and ethylene. It can be seen that it has selectivity.

Example 4 Preparation of Ethylene from Propylene under ZSM-5 Catalyst with Temperature

In Example 1, except that the temperature is changed to 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃ and 650 ℃, respectively, was carried out in the same manner as in Example 1 to produce ethylene from propylene and the results are shown in FIG. Described.

As shown in Figure 5 it can be seen that the difference in the conversion rate of propylene and the selectivity of ethylene according to the temperature, it can be seen that the conversion and selectivity excellent at the same time at 550 to 600 ℃.

Example 5 Preparation of Ethylene from Propylene under ZSM-5 Catalyst at Partial Pressure

In Example 1, except that the partial pressure was changed as shown in FIG. 6, the same procedure as in Example 1 was carried out to produce ethylene from propylene, and the results are shown in FIG.

As shown in FIG. 6, it can be seen that the conversion rate of propylene and the selectivity of ethylene are clearly different according to the dilution ratio of propylene and nitrogen, and the dilution ratio of propylene and nitrogen is better at 1: 1 to 1: 30 and It can be seen that the selectivity is shown.

Specifically, when the injection amount of propylene is fixed at 4.6 ml / min, the nitrogen injection amount is in the range of 20 to 100 ml / min, that is, the dilution ratio of propylene and nitrogen is 1: 1 to 22, preferably 1: 1 to 20, more preferably 1 It can be seen that better conversion and selectivity are shown in: 4 to 16.5.

Example 6 Preparation of Ethylene from Propylene under Silyzed ZSM-5 Catalyst

Ethylene was prepared from propylene in the same manner as in Example 1 using the catalyst of silylated ZSM-5 (Si / Al ₂ molar ratio of 50) prepared in Preparation Example 3, and the conversion rate of propylene in FIG. And selectivity of ethylene.

As shown in FIG. 7, it can be seen that the catalyst of the silylated ZSM-5 differs significantly in the conversion of higher propylene and selectivity of ethylene.

Claims (11)

Preparing ethylene by reacting propylene under a ZSM-5 catalyst having a Si / Al ₂ molar ratio of 23 to 280;
Wherein the reaction is carried out at a temperature of 550-600 ° C., an hourly space velocity of propylene of 1-2 hours ⁻¹ and a propylene-nitrogen dilution ratio of 1: 4-1: 16.5. The method of claim 1,
The ZSM-5 catalyst is a method for producing selective ethylene from propylene having a Si / Al ₂ molar ratio of 30 to 100. The method of claim 1,
The ZSM-5 catalyst is a method for producing selective ethylene from propylene loaded with phosphorus 0.5 to 5% by weight. The method of claim 3,
Ethylene selected from propylene, characterized in that it is derived from one or more phosphorus compounds selected from phosphoric acid, ammonium monophosphate, diammonium phosphate, (C1-C10) alkylphosphorous acid and (C1-C10) alkylphosphate Manufacturing method. delete The method of claim 1,
The ZSM-5 catalyst is a method for producing selective ethylene from propylene, characterized in that treated with 10 to 25ml of the silylating agent based on 100g of ZSM-5 catalyst. The method of claim 6,
The silylating agent is one selected from Si (R ¹ ) _{4 - n} (OR ² ) _n , wherein R ¹ and R ² are independently of each other (C1-C10) alkyl and n is an integer from 1 to 4. Or a process for producing selective ethylene from two or more propylene. The method of claim 1,
Wherein the ZSM-5 catalyst is H-ZSM-5. The method of claim 1,
The ZSM-5 is characterized in that one or two or more selected from La, Zn, Ni, Fe, Ga, Cu, Pd, Al, Co, M, Ce, Cr, Au, Pt, Re, Ru, and Ir are supported. Process for producing selective ethylene from propylene. The method of claim 1,
Wherein said step is carried out in a fixed bed reactor or a fluidized bed reactor. The method of claim 1,
The method for producing selective ethylene from propylene having a conversion rate of propylene of 50% or more and ethylene selectivity of 40% or more.

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