KR20160014235A - Catalyst for production of light olefin and production method of light olefins through catalytic cracking of hydrocarbons using the catalyst - Google Patents

Abstract

Disclosed is a catalyst for manufacturing light olefin including ethylene and propylene by catalytic cracking of a hydrocarbon mixture having four to seven carbon atoms generated after naphtha cracking. The catalyst prevents activity of a catalyst from being degraded for a long term by having long catalytic life, while having physical and chemical properties of an existing catalyst by controlling chemical properties on the surface of crystal and inhibiting degradation of catalytic activity by carbon deposition. Provided in the present invention is a catalyst for manufacturing light olefin, which is a catalyst used in manufacturing of light olefin comprising ethylene and propylene by catalytic cracking a hydrocarbon mixture having four to seven carbon atoms generated after a naphtha cracking process. The catalyst has an outer surface acid site sealed by selective dealumination by having the zeolite catalyst treated and plasticized by an organic acid solution.

Description

FIELD OF THE INVENTION The present invention relates to a catalyst for the production of light olefins and a method for producing light olefins by catalytic catalytic cracking of a hydrocarbon mixture using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a catalyst for the production of light olefins and a process for producing light olefins by catalytic catalytic cracking of hydrocarbon mixtures using the same. More particularly, the present invention relates to a catalyst for catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after naphtha cracking, A catalyst capable of simultaneously improving the yield of light olefins and the catalyst life by improving the physicochemical properties of the catalyst for the preparation of light olefins used in the production of light olefins, and a process for producing light olefins by catalytic catalytic cracking of hydrocarbon mixtures using the same ≪ / RTI >

Ethylene and propylene are important raw materials for petrochemical products. Until now, most of ethylene and propylene have been produced by steam pyrolysis of hydrocarbons whose main components are paraffinic compounds, such as natural gas, naphtha and gas oil, at a high temperature of 800 ° C or higher under no catalyst condition without catalyst. In order to increase the yield of ethylene and propylene in steam cracking reaction of hydrocarbons, it is necessary to increase the conversion of hydrocarbons or increase the selectivity of olefins. However, various methods have been proposed to increase the yield of olefins because pure hydrothermal reaction only limits the conversion of hydrocarbons and selectivity of olefins.

Recently, catalytic decomposition technology using a catalyst has attracted attention as an energy saving technique which replaces the pyrolysis process. A typical technique used for producing light olefins through catalytic catalytic cracking is a catalytic cracking process using an acid catalyst. Particularly, zeolite among various acid catalysts is most widely used because it is easy to control the acidity through the change of the chemical composition of the zeolite, and the reaction conversion ratio and the yield of the light olefin finally obtained can be easily controlled due to the unique shape selectivity Because. ZSM-5, USY, REY, β-zeolite and the like are used as typical zeolites for catalytic catalytic cracking.

The ZSM-5 catalyst is a zeolite A having an 8-membered ring pore size and erionite and a 12-membered ring, Unlike the faujasite with super-cage, the mordenite with zeolite X and Y or the two-dimensional pore structure, the pore size of the medium-sized 10-membered ring And has a uniform pore size and structure by a pore structure formed by a three-dimensional intersection of a straight channel of 5.4 × 5.6 Å and a sinusoidal channel of 5.1 × 5.5 Å, (H. Krannila, WO Haag, BC Gates, J. Catal., Vol.135, p115, 1992), which is superior in shape selectivity, low inactivity and high in thermal stability due to high Si / Al ratio.

On the other hand, carbon deposition during the reaction is a major cause of the degradation of zeolite catalyst activity. Since the acid sites of the zeolite catalyst exist not only in the micropores but also on the crystal surface, the catalytic reaction proceeds even at the external surface acid sites. At the acid sites of the crystal surface, large molecules of hydrocarbons can be produced because there is no spatial limitation on the molecular shape and size of the product. The by-products thus formed are deposited on the surface of the crystal to block the diffusion of the molecules by blocking the pore openings, thereby causing the deactivation of the catalyst. Although the outer surface area of the zeolite is only about 5% of the total surface area, the reaction on the non-selective outer surface can not be ignored because carbon deposition takes place very quickly on the crystal surface. Therefore, in order to prevent the deactivation of the zeolite catalyst, it is important to remove the acid sites on the outer surface to improve the resistance of the catalyst to carbon deposition. That is, if the active sites existing on the outer surface are removed, it can be expected that the lifetime of the catalyst is greatly improved.

As the acidity of the catalyst is increased, the carbon deposition is so severe that studies for reducing the degree of deactivation by decreasing the catalyst acidity have continued. The most traditional reforming method to control zeolite acidity is dealumination. For example, by the method of steam treatment described in Weitkamp et al. (Catalysis and Zeolites, Fundamentals and Applications (J. Weitkamp and L. Puppe, Eds., Springer, 1999), pp. 127-155) , Treatment with silicon tetrachloride, treatment with hexafluorosilicate, and the like. Steam treatment of zeolite catalysts with strong acidity has also been shown to increase the yield of light olefins by suitably adjusting the ratio of Bronsted acid to Lewis acid (Chen, D., Sharma, S., Cardona-Martinez , N., Dumesic, JA, Bell, VA, Hodge, GD and Madon, RJ, "Acidity Studies of Fluid Catalytic Cracking Catalysts by Microcalorimetry and Infrared Spectroscopy", J. Catal., 136, 392-402 (1992)). However, in the steam treatment step, aluminum atoms are chemically removed from the crystalline silicate skeleton to form alumina particles, which cause partial occlusion of the pore entrances in the skeleton or affect the acid sites present in the zeolite skeleton, Which causes the structure to collapse and excessively reduce the acidity.

Another modification method is chemical vapor deposition of silicon tetrachloride on the zeolite to control the pore and surface acid sites of the zeolite, so that the selectivity of the specific product can be increased by using the shape selectivity of the zeolite. However, the chemical vapor deposition method has a disadvantage that it is expensive. To solve this problem, the research of the second generation catalyst is performed by the reaction in the liquid phase rather than the vapor deposition.

This method is a method of reacting a zeolite catalyst with a zeolite catalyst at a low temperature using TEOS (tetraethyl orthosilicate) or ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ), which is a compound containing silicon (Si) It is a method to remove. If the silane molecule is large, it can not enter into the zeolite pores, so it selectively reacts with the hydroxyl groups on the outer surface of the zeolite to shield the acid sites on the outer surface. However, depending on the throughput, there is a disadvantage that the acid sites of some outer surfaces remain or the silane molecules in the excessive treatment result in narrowing the pore openings as well as the acid sites on the outer surface, thereby lowering the activity and selectivity of the cracking reaction.

On the other hand, inorganic acid treatment methods such as hydrochloric acid, nitric acid, sulfuric acid and the like are also included in a conventional technique for inducing dealumination of zeolite, but these treatments do not show selectivity to the zeolite crystal surface. However, when oxalic acid is used, an aluminum oxalate complex is formed on the crystal surface of the zeolite to selectively remove aluminum atoms forming Bronsted or Lewis acid sites. This oxalic acid treatment method will minimize the undesirable side reactions occurring at the crystal surface of the zeolite catalyst, thereby increasing the selectivity of the hydrocarbon decomposition reaction and at the same time inhibiting carbon deposition and prolonging the catalyst life. However, there have been no reports on the production of light olefins by catalytic cracking of a mixture of C4 to C7 hydrocarbons such as C5 oil produced after a naphtha cracking process using a catalyst having a controlled acid density on the outer surface in this manner, C7 hydrocarbons in the production of light olefins by catalytic cracking has not been predicted to be technically satisfactory in terms of yield and catalyst life.

On the other hand, natural gas crackers for obtaining ethylene from natural gas, which is comparatively less expensive than naphtha due to rising oil prices and heavy crude oil, have been added. However, since ethylene can be selectively produced, it is unbalanced in the supply and demand of propylene Unlike in the case of natural gas-rich European countries, crude oil importing countries such as Korea depend on naphtha cracking, which is a disadvantage in terms of reducing greenhouse gas emissions. In Korea, the amount of ethylene obtained from the naphtha cracking process reaches 5 million tons per year, and the amount of C5 oil discharged as a by-product reaches 700 thousand tons, but it can not be used effectively. Therefore, there is a high need to develop a technology for controlling the supply and demand of ethylene, propylene and butene. For this purpose, a light olefin restructuring technology is required and utilization of C5 oil as a raw material for light olefin restructuring is also important.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a catalyst for the production of light olefins comprising ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms, which is produced after naphtha cracking, The present invention relates to a catalyst for the production of light olefins which can improve the prevention of catalyst deactivation in the long term by exhibiting better catalyst lifetime characteristics while maintaining the physical and chemical properties of existing catalysts by controlling the chemical properties of the surface, ≪ / RTI >

Also, it is intended to provide a catalyst for the production of light olefins which is capable of inhibiting deactivation of a catalyst and maximizing the yield of light olefins by introducing phosphorus and a rare earth metal into a catalyst whose acidity on the outer surface of the zeolite is controlled.

And a method for producing light olefins from a hydrocarbon mixture having 4 to 7 carbon atoms using the catalyst.

In order to solve the above problems, the present invention provides a catalyst used for producing light olefins comprising ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after a naphtha cracking step, Wherein the catalyst is treated and baked with an organic acid solution, and the outer surface acid point is shielded through the selective dealumination reaction.

Also, the zeolite catalyst has at least one skeletal type selected from the group consisting of MFI, MOR, LTA, BEA, FAU and TON, and the Si / Al atomic ratio is 5 to 1000.

The organic acid may be at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and tartaric acid. do.

And the organic acid is oxalic acid.

Wherein the concentration of the organic acid solution is 0.01 to 4M, and the organic acid solution to the catalyst volume ratio is 1: 1 to 10: 1.

The present invention also provides a catalyst for producing light olefins, wherein the catalyst further comprises phosphorus.

In addition, the phosphorus is phosphoric acid (H ₃ PO _4), ammonium phosphate _{((NH 4) H 2 PO} 4), phosphoric acid ammonium _{((NH 4) 2 HPO 4} ) and tricalcium phosphate of ammonium _{((NH 4) 3 PO 4} ) Wherein the catalyst comprises at least one phosphorus precursor selected from the group consisting of titanium and titanium.

The phosphorus is introduced by impregnation or ion exchange in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the catalyst.

And the catalyst further comprises a rare earth metal.

The rare earth metal may be at least one selected from the group consisting of La, Ce, Pr, Ne, Prommium, Sm, Eu, Gd, Wherein the catalyst is at least one selected from the group consisting of dysprosium (Dy), holmium (Ho), erbium (Er), thorium (Tm), ytterbium (Yb) and lutetium (Lu).

And the rare earth metal content is 2 or less in terms of the atomic ratio to the phosphorus.

Also, the hydrocarbon mixture having 4 to 7 carbon atoms is a C5 oil produced after the naphtha cracking process.

According to another aspect of the present invention, there is provided a process for producing light olefins comprising ethylene and propylene by catalytic catalytic cracking of a mixture of hydrocarbons having 4 to 7 carbon atoms, wherein the hydrocarbons at a reaction temperature of 300 to 700 ° C Wherein the mixture is reacted at a weight hourly space velocity (WHSV) of 1 to 20 h < ^-1 >.

According to the present invention, in a zeolite catalyst used for producing light olefins containing ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after a naphtha cracking step, an outer surface of the zeolite is treated with an organic acid solution such as oxalic acid The use of a catalyst having the property of removing only the acid sites on the outer surface by performing the selective dealumination reaction suppresses the rapid carbon deposition on the outer surface at the acid sites to improve the catalyst stability and improve the lifetime of the catalyst Catalytic catalytic cracking of a catalyst for producing an effective light olefin and a hydrocarbon mixture having 4 to 7 carbon atoms to produce a light olefin comprising ethylene and propylene.

In addition, when the phosphorus and rare earth metals are introduced into a zeolite catalyst pretreated with an organic acid such as oxalic acid, the acid and base properties of the catalyst can be controlled. When a catalyst having an appropriate atomic ratio is prepared, the production of light olefins And a method for producing light olefins containing ethylene and propylene by catalytic catalytic cracking of a catalyst for the production of light olefins having a stable and excellent activity over a long period of time and a hydrocarbon mixture having 4 to 7 carbon atoms.

FIG. 1 is a graph showing the results of measurement of yields of light olefins according to production examples using a ZSM-5 catalyst prepared according to Example 1 and Comparative Examples 1 to 3,
FIG. 2 is a graph showing the results of measurement of the yield and inactivation degree of light olefins according to the production examples using the ZSM-5 catalyst prepared according to Examples 1 and 2 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It is to be understood that various equivalents and modifications may be substituted for those at the time of the present application.

The present invention relates to a catalyst for use in the production of light olefins comprising ethylene and propylene by catalytic catalytic cracking of a mixture of hydrocarbons having 4 to 7 carbon atoms produced after a naphtha cracking process, And the outer surface acid point is shielded through selective de-aluminumation reaction.

The catalyst for the production of light olefins according to the present invention is used for preparing light olefins containing ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after a naphtha cracking step, Can be used for producing light olefins containing ethylene and propylene by catalytic catalytic cracking of C5 oil produced after the naphtha cracking process.

In the present invention, the skeleton type of the catalyst may be MFI, MOR, LTA, BEA, FAU or TON, and the Si / Al atomic ratio of 5 to 1000 may be selected. In this case, it is more preferable to select Si / Al atomic ratio of 5 to 500, more preferably 10 to 300, and most preferably 20 to 200. When the Si / Al atomic ratio is less than 5, there is no significant influence on the change of the catalyst activity. However, there may be a risk of inactivation due to coking or the like while the amount of the catalyst is increased. The conversion rate of the catalytic catalytic cracking reaction of the hydrocarbon mixture having 4 to 7 carbon atoms may not be satisfactory.

Further, the outer surface of the zeolite catalyst is treated and baked with an organic acid solution so as to shield the outer surface acid sites, whereby the carbon deposition is inhibited at the acid sites on the outer surface through the selective dealumination reaction, thereby improving the catalyst stability and lifetime of the catalyst . Oxalic acid is the most suitable organic acid to be used for selective dealumination of the outer surface. In addition, malonic acid, succinic acid, and succinic acid, which can not penetrate into zeolite pores due to their large molecular size for selective dealumination, Glutaric acid, adipic acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, and tartaric acid.

The preparation of a zeolite catalyst treated with such an organic acid solution can be carried out, for example, by: (a) hydrating an organic acid solution into water; (b) adding a zeolite catalyst to the hydrated solution to remove the acid sites on the outer surface through the dealumination reaction; And (c) washing, drying and heat-treating the solid product obtained in the step (b).

The organic acid solution used in the treatment of the organic acid solution may be used at a concentration of 0.01 to 4M at a volume ratio of 1: 1 to 10: 1 with respect to the catalyst to be treated, preferably at a concentration of 0.1 to 2M, : 1 to 5: 1. The heat treatment may be performed at 500 to 750 ° C for 1 to 10 hours.

In the present invention, the zeolite catalyst before the treatment with the organic acid solution may be cation-substituted. The cation substitution is for exchanging zeolite generally substituted with sodium ion (Na ⁺ ) with a proton (H ⁺ ), and the zeolite catalyst substituted with a proton is more effective in cracking reaction because acid strength is increased compared to other cations. The cation exchange may be carried out by adding the zeolite catalyst to a solution for substituting cation at 70 to 90 ° C and stirring the mixture at the same temperature for 2 to 4 hours. After the cation-substituted aqueous solution is filtered and washed, The cation exchange process may be repeated one to three times. The solution used in such cation exchange, the ammonium nitrate (NH ₄ NO _3), ammonium chloride (NH ₄ Cl), the group consisting of ammonium carbonate _{((NH 4) 2 CO 3} ) and ammonium fluoride (NH ₄ F) 1 < / RTI >

The cation-exchanged zeolite catalyst is preferably heat-treated. The heat treatment may be performed by firing at 400 to 700 ° C for 3 to 10 hours. If the temperature of the heat treatment is less than 400 ° C, the ammonium salt primarily substituted with the catalyst may not be sufficiently removed, so that the acid strength of the zeolite may be decreased. If the temperature exceeds 700 ° C, the catalyst collapse and the Bronsted acid point may disappear . If the heat treatment temperature is less than 3 hours, it may be difficult to remove sufficient ammonium salt, and if it exceeds 10 hours, power loss may occur. Here, it is preferable that the cation-substituted catalyst is dried at 100 to 120 ° C for 5 to 15 hours before the heat treatment, and then the heat treatment is performed.

According to one embodiment of the present invention, a phosphor may be further included in the zeolite catalyst treated with an organic acid. The phosphorus-containing catalyst may be impregnated with a phosphorus precursor or formed by an ion exchange method in a zeolite catalyst (which may be a cation-substituted catalyst) treated with an organic acid. In the present invention, however, It is preferable to use an impregnation method.

The impregnation of the phosphorus precursor with a zeolite catalyst treated with an organic acid can be carried out, for example, by a method in which the phosphorus precursor is hydrated in water, a zeolite catalyst treated with an organic acid is added to the hydrated solution, followed by drying and heat treatment . Specifically, the phosphorus precursor is dissolved in an amount of water (distilled water) capable of completely saturating the pore volume of the zeolite, stirred at room temperature for 1 to 2 hours, introduced into the zeolite catalyst treated with the organic acid, Followed by drying in an oven at 90 to 110 ° C. for 10 to 15 hours and then calcining at 500 to 750 ° C. for 1 to 10 hours. If the calcination temperature is less than 500 ° C., the organic and inorganic materials contained in the phosphorus precursor may not be completely removed. If the calcination temperature is more than 750 ° C., the phosphorus is not preferable from the viewpoint of energy efficiency, The organic and inorganic removal performance may be deteriorated.

At this time, it is important that the phosphorus precursor introduction amount is set to an optimal range with respect to the amount of the catalyst to be finally produced and the carbon deposition amount according to the catalytic reaction. Therefore, in the present invention, the phosphorus precursor introduction amount is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 3 parts by weight, and most preferably 0.1 to 1.5 parts by weight, based on 100 parts by weight of the zeolite catalyst , And most preferably 0.1 to 1 part by weight.

The phosphorus precursor is not particularly limited, but preferably phosphoric acid (H ₃ PO ₄ ), ammonium phosphate ((NH ₄ ) H ₂ PO ₄ ), ammonium phosphate ((NH ₄ ) ₂ HPO ₄ ) ammonium _{((NH 4) 3 PO 4} ) or the like can be used.

According to another embodiment of the present invention, a catalyst capable of controlling acid and base characteristics of the catalyst can be realized by further including a rare earth metal in the zeolite catalyst into which the phosphorus is introduced. At this time, the rare earth metal may be introduced by treatment with a rare earth metal precursor.

The impregnation or ion exchange method is used as the rare earth metal precursor introduction method, but in the present invention, it is preferable to use an impregnation method which is easy to control acid and base properties. The method of impregnating the rare earth metal precursor with the phosphorus-introduced zeolite catalyst can be carried out in a similar manner to the phosphorus precursor introduction, that is, the rare earth metal precursor is hydrated in water and the zeolite catalyst into which the phosphorus is introduced into the hydrated solution Impregnation, drying and heat treatment may be used. Specifically, the rare earth metal precursor is dissolved in an amount of water (distilled water) capable of completely saturating the pore volume of the zeolite, stirred at room temperature for 1 to 2 hours, introduced into the zeolite catalyst into which the phosphorus is introduced, Followed by drying in an oven at 90 to 110 ° C. for 10 to 15 hours, followed by baking at 500 to 750 ° C. for 1 to 10 hours.

At this time, it is important that the rare earth metal precursor introduction amount is set to an optimal range in relation to the amount of acid, the amount of the base and the amount of carbon deposition according to the catalytic reaction in the final catalyst. Therefore, in the present invention, the content of the rare earth metal precursor introduced is preferably 2 or less in terms of atomic ratio to phosphorus, more preferably 0.1 to 1.5 in atomic ratio, and 0.2 to 0.5 in atomic ratio Most preferred.

As the rare earth metal contained in the rare earth metal precursor, lanthanum (La), Ce, Pr, Ne, Prommium, Sm, At least one member selected from the group consisting of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thorium (Tm), ytterbium (Yb) and lutetium (Lu) Lanthanum may be selected. For example, when lanthanum is selected as the rare earth metal, lanthanum nitrate (La (NO ₃ ) ₃ .6H ₂ O) may be introduced in the form of a precursor.

The catalyst for producing light olefins according to the present invention can be used in the production of light olefins containing ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after the naphtha cracking process. At this time, the hydrocarbon mixture is reacted at a reaction temperature of 300 to 700 ° C. in the presence of the mixed catalyst at a weight hourly space velocity (WHSV) of 1 to 20 h ^-1 to prepare a light olefin. If the weight-space velocity is less than 1h ^-1 is possible to increase the conversion rate, but may reduce the selectivity due to side reaction, 20h ^- if more than ¹ may reduce the conversion rate and lead to decreased catalyst life.

Example  One

100 ml of 1 molar ammonium nitrate (NH ₄ NO ₃ , manufactured by Junsei) was prepared at 80 ° C. for cation exchange with the ZSM-5 catalyst. Then, a ZSM-5 catalyst (Si / Al atomic ratio: 140, ), And the mixture was stirred at 80 占 폚 for 3 hours. The cation-substituted aqueous solution was subjected to a further two-step cation exchange process through filtration and washing. The cation-substituted solid product was dried at 110 ° C for 10 hours and then calcined at 550 ° C for 4 hours to prepare a cation-substituted ZSM-5 catalyst. Then, 25 ml of oxalic acid solution having a concentration of 0.1 mole per 1 g of the catalyst was prepared with respect to the cation-substituted ZSM-5 catalyst, and the mixture was stirred under refluxing at 80 ° C for 6 hours. Thereafter, the catalyst was filtered with hot distilled water to remove the aluminum oxalate complex, dried at room temperature for 24 hours, at 110 ° C for 2 hours, and then calcined at 550 ° C for 4 hours to prepare a ZSM-5 catalyst having acid sites selectively removed on its outer surface .

Comparative Example  One

A pure ZSM-5 catalyst was prepared in the same manner as in Example 1, except that the solution was not treated with the oxalic acid solution in Example 1.

Comparative Example  2

A method using a silica precursor to selectively remove the acid sites on the outer surface of the catalyst may be considered. For comparison with the catalyst treated with an organic acid according to the present invention, a silica precursor is used to remove ZSM-5 Catalyst. To this end, the cation-substituted ZSM-5 catalyst prepared in Comparative Example 1 was treated with a silica precursor (tetraethyl orthosilicate) in a liquid phase to support silica on the outer surface. The ZSM-5 catalyst was washed three times with hexane to remove moisture, and tetraethylorthosilicate dissolved in hexane was diluted so that the amount of silica supported was 1.5 parts by weight with respect to 100 parts by weight of the ZSM-5 catalyst. . The unreacted silica precursor was washed with hexane more than three times to remove it, dried at 110 ° C and then calcined at 550 ° C for 4 hours to prepare a silica-supported ZSM-5 catalyst on the outer surface.

Comparative Example  3

To the catalyst prepared in Comparative Example 2, 25 ml of a 0.1 molar oxalic acid solution per 1 g of the catalyst was prepared and stirred while refluxing at 80 캜 for 6 hours. Thereafter, the catalyst was filtered with hot distilled water to remove the aluminum oxalate complex, dried at room temperature for 24 hours, at 110 ° C for 2 hours, and then calcined at 550 ° C for 4 hours to prepare a ZSM-5 catalyst in which acid sites on the outer surface were selectively removed .

Example  2

A phosphorus precursor quantitated to contain 0.3 parts by weight of phosphorus based on 100 parts by weight of the ZSM-5 catalyst prepared in Example 1 was supported by impregnation. To this end, a predetermined amount of phosphoric acid (85%, H ₃ PO ₄ , manufactured by Sigma-Aldrich) corresponding to distilled water sufficient to saturate the pores with respect to the weight of the catalyst was dissolved in the ZSM-5 catalyst prepared in Example 1, Optionally impregnated with sufficient impregnation. When all the phosphoric acid was impregnated, the catalyst was dried in an oven at 100 ° C. for 12 hours and finally calcined at 550 ° C. for 4 hours to prepare phosphorus-introduced ZSM-5 catalyst. Then, lanthanum (La) among the rare earth metals was selected as a ZSM-5 catalyst into which phosphorus was introduced, and a catalyst quantitatively determined to have a lanthanum / phosphorus atom ratio of 0.3 was prepared. The introduction of lanthanum was prepared by impregnation, and a predetermined amount of lanthanum nitrate (La (NO ₃ ) ₃ .6H ₂ O, manufactured by Sigma-Aldrich) was dissolved in distilled water sufficient to saturate pores with respect to the weight of the catalyst, The prepared phosphor was loaded into the introduced ZSM-5 catalyst so that the impregnation was selectively and sufficiently carried in the pores. When all the quantities of lanthanum were impregnated, the catalyst was dried in an oven at 100 ° C. for 12 hours and finally calcined at 550 ° C. for 4 hours to prepare phosphorus and lanthanum-introduced ZSM-5 catalysts.

Experimental Example  1: Oxalic acid treated ZSM -5 production of light olefins by catalytic catalytic cracking of hydrocarbon mixtures using catalysts

In order to analyze the production yields of light olefins, particularly ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture using the catalyst according to the present invention, the following production reaction was carried out using the catalyst prepared in Example 1 and Comparative Examples 1 to 3 Respectively. The hydrocarbon mixture used as the reactant is a primary hydrogenated C5 oil used in the actual factory, and contains a large amount of cyclopentene, which is a coke inducing substance, so that it is easy to measure the quick deactivation behavior. The composition of the oil is shown in Table 1 below.

[Manufacturing reaction example]

The catalysts prepared according to Example 1 and Comparative Examples 1 to 3 were filled in a quartz reactor in an amount of about 15 to 30 mg for the catalytic catalytic cracking reaction of the C5 oil, Lt; 0 > C for 1 hour. After the catalytic activation, the reaction proceeded as the reactants passed through the catalyst bed in the reactor continuously. The weight hourly space velocity (WHSV) of the reactants was maintained at 8 h ^-1 and the catalytic catalytic cracking reaction temperature of the C5 oil was 600 ° C. The products produced after the reaction were analyzed by gas chromatography. The conversion of C5 fraction and the selectivity and yield of light olefins (ethylene and propylene) were calculated according to the reaction time of each catalyst, Respectively. Here, the conversion of C5 fraction, the selectivity of light olefins (ethylene), and the yield of light olefins (ethylene) are calculated according to the following equations (1) to (3).

1, when ZSM-5 catalyst (Comparative Example 1) was used, ZSM-5 catalyst having high initial activity but having a catalyst deactivation (yield reduction rate) Comparative Examples 2 to 3), and the catalyst deactivation degree was the slowest in the ZSM-5 catalyst treated with oxalic acid. The ZSM-5 catalyst treated with silica (Comparative Example 2) was partially inactivated compared to the pure ZSM-5 catalyst (Comparative Example 1), but the ZSM-5 catalyst treated with oxalic acid It can be seen that the initial yield is slightly higher than that of Example 1), while the yield reduction rate is faster. In addition, the ZSM-5 catalyst (Comparative Example 3) in which the silica and oxalic acid solution were mixed to remove the acid sites on the outer surface had a somewhat improved yield reduction rate compared to the ZSM-5 catalyst treated with silica (Comparative Example 2) It was found that the yield did not reach the ZSM-5 catalyst (Example 1) treated, while the yield was low. This difference in catalyst deactivation is due to the fact that the catalyst treated with the oxalic acid solution prepared according to the present invention is more resistant to carbon deposition than the pure ZSM-5 catalyst or the silica-treated catalyst because the external surface acid point is completely removed. This improved resistance to carbon deposition leads to less production of C5 olefins used as reactants and C5 or higher products produced by polymerisation of isomers and carbonium ions of C5 olefins produced during the course of the reaction, Thereby improving the long-term activity of the cracking reaction.

Experimental Example  2: Oxalic acid treatment with phosphorus and rare earth metals ZSM - 5 catalyst  Production yield of light olefins by catalytic catalytic cracking of hydrocarbons mixture and its effect on catalytic activity

ZSM-5 prepared according to Example 2 for the production yield analysis of light olefins, in particular ethylene and propylene, by catalytic catalytic cracking of hydrocarbon mixtures using oxalic acid-treated ZSM-5 catalyst with phosphorus and rare earth metals incorporated according to the present invention The production reaction was carried out using the catalyst according to the preparation reaction, and the results are shown in FIG. The results for the catalyst prepared according to Example 1 and Comparative Example 1 are shown for comparison and the hydrocarbon mixture used as the reactant is C5 oil of the composition of Table 1 above.

2, the light olefin yield and long-term activity can be measured by treating the catalyst with oxalic acid after treatment with a pure ZSM-5 catalyst (Comparative Example 1) or with a oxalic acid solution rather than a ZSM-5 catalyst (Example 1) It can be seen that it is the most excellent in the ZSM-5 catalyst (Example 2) in which the rare earth metal is introduced. That is, the introduced phosphorus component appropriately performs a role of further inhibiting deactivation of the ZSM-5 catalyst treated with oxalic acid by preventing dealumination in the framework, while the lanthanum component improves the basicity of the catalyst, And thus the selectivity of light olefins is increased. Thus, as in Example 2, a catalyst is prepared so as to control the acid and base characteristics of the catalyst to the optimum state, thereby suppressing the deactivation of the catalyst and improving the yield of light olefin Can be maximized.

While the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Such modifications and changes are to be considered as falling within the scope of the following claims.

Claims (13)

A catalyst used for producing light olefins comprising ethylene and propylene by catalytic catalytic cracking of a hydrocarbon mixture having 4 to 7 carbon atoms produced after a naphtha cracking process,
Wherein the catalyst is treated and fired with a solution of an organic acid in a zeolite catalyst to shield the outer surface acid sites through selective dealumination. The method according to claim 1,
Wherein the zeolite catalyst has at least one skeletal type selected from the group consisting of MFI, MOR, LTA, BEA, FAU and TON, and the Si / Al atomic ratio is 5 to 1000. The method according to claim 1,
Wherein the organic acid is at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and tartaric acid. The method according to claim 1,
Wherein the organic acid is oxalic acid. The method according to claim 1,
Wherein the concentration of the organic acid solution is 0.01 to 4M, and the organic acid solution to the catalyst volume ratio is 1: 1 to 10: 1. The method according to claim 1,
Wherein the catalyst further comprises phosphorus. The method according to claim 6,
The phosphorus is a phosphoric acid (H ₃ PO _4), ammonium phosphate _{((NH 4) H 2 PO} 4), phosphoric acid ammonium _{((NH 4) 2 HPO 4} ) and tricalcium phosphate of ammonium _{((NH 4) 3 PO 4} ) Wherein the catalyst comprises at least one phosphorus precursor selected from the group consisting of iron and iron. The method according to claim 6,
Wherein the phosphorus is introduced by impregnation or ion exchange in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the catalyst. The method according to claim 6,
Wherein the catalyst further comprises a rare earth metal. 10. The method of claim 9,
The rare earth metal is selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium Wherein the catalyst is at least one selected from the group consisting of Dy, Ho, Er, Tm, ytterbium and lutetium. 10. The method of claim 9,
Wherein the rare earth metal content is 2 or less in terms of the atomic ratio to the phosphorus. The method according to claim 1,
Wherein the hydrocarbon mixture having 4 to 7 carbon atoms is a C5 oil component produced after the naphtha cracking process. A process for producing light olefins comprising ethylene and propylene by catalytic catalytic cracking of a mixture of hydrocarbons having 4 to 7 carbon atoms,
A process for preparing a light olefin comprising reacting the hydrocarbon mixture at a reaction temperature of 300 to 700 ° C in the presence of a catalyst according to any one of claims 1 to 12 at a weight hourly space velocity (WHSV) of 1 to 20 h ^-1 .

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