KR101587345B1

KR101587345B1 - Heterogeneous catalysts for ethylene production via ethanol dehydration and production method of ethylene using same

Info

Publication number: KR101587345B1
Application number: KR1020140042722A
Authority: KR
Inventors: 조정모; 김인애; 서영종
Original assignee: 롯데케미칼 주식회사
Priority date: 2014-04-10
Filing date: 2014-04-10
Publication date: 2016-01-20
Also published as: KR20150117378A

Abstract

Disclosed is an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrous ethanol into ethylene, an ethanol dehydration catalyst having an excellent ethylene production yield even in a low temperature region, and a process for producing ethylene using the same. The present invention relates to an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrated ethanol to ethylene, wherein the catalyst comprises ethanol in an amount of 0.05 to 1% by weight of gallium (Ga) in ZSM-5 Catalyst and a process for producing ethylene using the same.

Description

TECHNICAL FIELD [0001] The present invention relates to an ethanol dehydration catalyst for producing ethylene, and a method for producing ethylene using the same. BACKGROUND ART [0002]

The present invention relates to an ethanol dehydration catalyst and a process for producing ethylene using the same, and more particularly to an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrated ethanol into ethylene under low temperature conditions and a process for producing ethylene using the same will be.

The present invention is derived from research carried out as part of the industrial fusion technology development project supported by the Ministry of Commerce, Industry and Energy in 2013.

[Assignment number: 2013-10042712, Title: Development of new innovative chemical process and new catalyst]

As the potential for depletion of fossil fuels increases, there is an increasing interest in environmentally friendly new carbon resources that are renewable and sustainable. Among these resources, ethanol obtained from the fermentation of plants is mass-produced in Brazil and the United States, and many advanced and developing countries including these countries already use ethanol as transportation energy.

Ethanol can be used not only as a potential alternative energy source, but also in the production of various olefins, including ethylene, the basic raw material of the petrochemical industry through dehydration. The high conversion of ethylene by dehydration of ethanol is an endothermic reaction, and the process can be said to be an energy intensive process which consumes a lot of heat, such as pretreatment of raw materials and impurities removal of reactants and products. Therefore, it is required to design an energy-saving catalyst process capable of producing ethylene at a low temperature at a high yield.

Commercial dehydration catalysts for ethanol are generally alumina based catalysts, and ethylene production is performed in a high temperature range of 300 to 500 ° C. This requires a large amount of heat to control the reaction temperature and to preheat the raw material, and it may cause a lot of cost and problems from the operation and design of high temperature and high pressure. In addition, even if high yield of ethylene can be produced, when the conversion of ethanol and the selectivity of ethylene are not guaranteed at the same time in a certain temperature range, the performance of the catalyst as well as the post-treatment purification process using ethylene as a raw material Resulting in additional costs and lower purity of the product.

No. 0891001 discloses a process for preparing ZSM-5 / SAPO-34 complex catalyst by performing a series of steps of hydrothermally synthesizing and firing a crystalline ZSM-5 obtained by hydrothermal synthesis into SAPO-34 production process And a method of converting the oxygen-containing compound into a light olefin under the ZSM-5 / SAPO-34 composite catalyst obtained by this method to select a light olefin having a C2 to C4 range of at least 70 carbon mole% And a selectivity for propylene to [C3 / C2] ratio of 1.0 or higher can be maintained.

Patent No. 1085046 relates to a process for producing light olefins in the C2 to C4 range from oxygen-containing compounds such as methanol and dimethyl ether under a mordenite catalyst. Propylene and butene can be obtained in a yield of 60% by weight or more, In particular, it discloses a process for producing light olefins in which butene can be obtained at a very high yield of about 30% by weight.

Open Patent Application No. 2011-0043878 discloses a method of preparing SAPO-34 microspheres by preparing a microspheres by spray-drying a mixed slurry containing crystallized un-dried SAPO-34 slurry, a binder and additives, And SAPO-34 microspheres for use in a circulating fluidized bed reactor produced by this method, which exhibit high strength and excellent reaction activity.

(HZSM-5 Catalysts in Dehydration of Ethanol to Ethylene, Catalyst Letter 124, 384-391 (2008)) discloses that H ZSM-5 zeolite catalyst with phosphorus (P) impregnated with ZSM-5-ZSM-5 catalyst, which is a process for the dehydration of H- As well as the use of the same. In this paper, ethylene is mainly produced at 573 ~ 713K in the case of catalysts with a phosphorus content of 3.4 wt% or more, and ethylene and high hydrocarbon (C3-C9 + aliphatic and aromatic) High temperature dehydration of the catalyst is an essential reaction in order to enable the conversion of ethanol to ethylene in the catalyst having a phosphorus content of 3.4 wt% or more.

The catalysts disclosed in these patents and non-patent documents have a low yield of ethylene, selectively have a limitation in producing only ethylene in high purity, and can be said to be an inefficient process in which high energy is consumed for a high temperature reaction.

U.S. Pat. No. 4,873,392 discloses a catalyst for the conversion of ethanol to ethylene, which is a lanthanum-modified H-ZSM-5 catalyst, with improved catalytic activity at low temperatures. This patent suggests the possibility of the ethanol dehydration catalyst in a relatively low temperature range, however, a very low space velocity (WHSV) is required to exhibit significant catalytic activity, and the ethylene yield is also unsatisfactory.

Non-Patent Document 2 (Nina Zhan, Yi Hu, Heng Li, Dinghua Yu, Yu Wang Han, He Huang, Lanthanum-Phosphorous modified HZSM-5 catalysts in dehydration of ethanol to ethylene: A comparative analysis, Catalysis Communications 11, 633-637 2010) is a paper on the production of ethylene from hydrous ethanol using ZSM-5 catalyst impregnated with both lanthanum and phosphorus. In the case of a catalyst impregnated with both lanthanum and phosphorus, However, when a raw material having a high ethanol content is used, the activity is deteriorated. In order to overcome this problem, the reaction temperature must be set to a high temperature.

Some prior art documents provide examples using catalysts incorporating gallium into zeolites.

Non-Patent Document 3 (FJ Machadoa, CM Lopez, Y. Camposa, A. Bolivar, S. Yunes, The transformation of n-butane overGa / SAPO-11, The role of extra- framework gallium species, , 226, 241-252 (2002)) was used to prepare olefins from n-butane using a zeolite catalyst having gallium introduced as a dehydrogenation catalyst required for the production of isobutene. In this document, it has been reported that the isobutene selectivity of the product is improved through the dehydrogenation of normal butane when the zeolite catalyst with gallium at 500 ° C. under atmospheric pressure and relatively high temperature conditions is used as a catalyst. The catalyst used is more specifically a catalyst in which SAPO-11 is a starting catalyst and gallium is introduced at 0.25-2.2 wt%. However, since the olefin compound is prepared using a non-alcohol hydrocarbon compound as a raw material, the reaction follows the mechanism of dehydrogenation reaction (reaction mechanism) rather than dehydration reaction, and the selectivity of olefin is improved at a high temperature of 500 ° C .

In the non-patent reference 4 (R. Barthos, A. Szechenyi, and F. Solymosi / Decomposition and Aromatization of Ethanol on ZSM-Based Catalysts / J. Phys. Chem. B / 110, 21816-21825 Catalyst characteristics related to the improvement of selectivity of aromatic compounds are being studied using the added raw materials. Catalysts having excellent selectivity for the production of aromatics in a high temperature reaction at 500 to 600 ° C in a catalyst prepared by using H-ZSM5 as a starting catalyst and adding 2 wt% of metal (molybdenum, rhenium, zinc, gallium, etc.) The results of screening were presented, but no study on the selectivity or yield improvement of ethylene as the final product from the dehydration reaction of ethanol was conducted.

Non-patent document 5 (A. Ausavasukhi, T. Sooknoi / Additional Brønsted acid sites in [Ga] HZSM-5 formed by the presence of water / Applied Catalysis A: General / 361, 93-98 2. However, when a catalyst obtained by hydrothermally treating 1 wt% of steam at 425 ° C in the production of Ga-ZSM-5 by adding gallium at 3 wt% is applied, or when the water is directly added to the reactant stream, Experimental results are presented.

In these non-patent documents, since the reactants are not used as alcohols or the desired reaction product is not ethylene, the non-patent documents can not be used for the production technology of ethylene through the dehydration reaction of ethanol, which will be described later in the present invention In addition to the efficient catalytic reaction, the chemical route as well as the technical purpose can be seen as very different. The catalysts according to these processes have no or very limited ethylene selectivity or yield when ethylene is produced through the dehydration reaction of ethanol.

DISCLOSURE OF THE INVENTION Accordingly, it is an object of the present invention to provide an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrous ethanol into ethylene, which is excellent in ethylene production yield even in a low temperature range, And to provide a manufacturing method thereof.

The present invention also provides an ethanol dewatering catalyst having improved thermal stability of the catalyst and excellent inhibition of activity lowering by coking, and a process for producing ethylene using the same.

Also, it is intended to provide an ethanol dehydration catalyst and a process for producing ethylene using the same, in which ethylene can be obtained at a high yield without inactivation for a long time under a reaction condition of a low temperature region and a relatively high space velocity.

In order to solve the above problems, the present invention provides an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrated ethanol to ethylene, wherein the catalyst comprises 0.05 to 1% by weight of gallium (Ga) in ZSM-5 By weight based on the total weight of the dehydration catalyst.

Also, the present invention provides an ethanol dehydration catalyst characterized in that the water content of the hydrous ethanol is 30 wt% or less.

Also, the ZSM-5 has an Si / Al ₂ molar ratio of 20 to 45.

Also, the catalyst may further contain 0.05 to 0.5% by weight of lanthanum (La).

Also, the catalyst has an ethanol conversion rate of 99% or more and an ethylene selectivity of 96% or more as measured under the following conditions.

[Measuring conditions]

Measurement of ethanol conversion and ethylene selectivity after dehydration for 240 hours at a space velocity (WHSV) of 5hr ^-1 and 240 ° C.

According to another aspect of the present invention, there is provided a method for producing ethylene by dehydration of a feedstock comprising anhydrous ethanol or hydrated ethanol, comprising the steps of: preparing 220 g of an ethanol-dehydrating catalyst according to any one of claims 1 to 5, Wherein the feedstock is reacted at a space velocity (WHSV) of 0.1 to 50 h < ^-1 > at a reaction temperature of ~ 260 < 0 > C.

The performance of the heterogeneous catalyst for the production of ethylene by dehydration reaction of ethanol is characterized by high water conversion rate which can guarantee high conversion of ethanol and high selectivity of ethylene and long life time which enables stable operation of the catalyst process while maintaining the activity of the catalyst for a long time For example. For this purpose, it is necessary to maximize the yield of ethylene, which is a desired reaction, and to design an optimal catalyst capable of suppressing the rate of deactivation by the deposition of carbon on the catalyst surface and pores due to generation of side reactions, caulking. Especially, in the case of ethylene which is used for the production of ethylene glycol in the petrochemical process, when the high purity production is not carried out, the life time of the partial oxidation catalyst for producing ethylene oxide is shortened. Is required.

According to the present invention, as an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrated ethanol into ethylene, ZSM-5 is used as a base catalyst and gallium is contained at an optimum content, and even at a low temperature region of 220 to 260 ° C An energy-saving ethanol dehydration catalyst capable of producing ethylene at a high yield without being inactivated for a long time at a relatively high space velocity as well as capable of producing ethylene at a high yield, A manufacturing method can be provided.

1 is a graph showing X-ray diffraction analysis results of an ethanol dehydration catalyst prepared according to Examples 3, 4, 6, 7, 8 and Comparative Example 1 of the present invention.

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.

In order to selectively produce ethylene at a high yield while maintaining or maintaining the performance of the dehydration reaction of the catalyst in the low temperature region in the ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrous ethanol to ethylene, It is important to select the appropriate additives and composition, and optimize the feed conditions of the reactants to increase the conversion and selectivity of the desired product. Accordingly, it is required to develop a catalyst for designing an energy-saving process capable of obtaining ethylene at a high yield. In order to secure economical efficiency in relation to stable operation and maintenance of the process, Is required. Under these circumstances, the inventors of the present invention have found that ZSM-5 having a high acidity having a specific Si / Al ₂ molar ratio is selected as a basic catalyst and gallium is contained as a specific metal component, And it has been found that there is an optimum point of gallium content which enables ethylene production at a high yield and yield ethylene at a high yield without long inactivation under high space velocity reaction conditions.

Accordingly, the present invention relates to an ethanol dehydration catalyst for converting a feedstock containing anhydrous ethanol or hydrated ethanol to ethylene, wherein the catalyst contains ZSM-5 in an amount of 0.05 to 1% by weight of gallium (Ga) Ethanol dehydration catalyst.

In the present invention, the feedstock comprises anhydrous ethanol or hydrated ethanol, and the oxygenated compound is essentially a feedstock comprising ethanol. The composition of the anhydrous ethanol and the hydrous ethanol is not particularly limited. The anhydrous ethanol may be, for example, 99.96% by weight of synthetic ethanol. In the case of the hydrous ethanol, the water content is preferably 30% by weight or less, , Ethanol-derived from woody, starchy plants. If the moisture content of the functional ethanol is more than 30% by weight, the de-alumina phenomenon of the catalyst may be accelerated and may not be suitable as a raw material. In addition, trace amounts of hydrocarbon impurities (alcohols having different carbon numbers, aldehydes, etc.), which can be contained in the feedstock in the range of several tens to several hundreds ppm, can be removed through a purification process before and after the reaction process, Can be considered.

In the present invention, the ethanol dehydration catalyst is selected as a basic catalyst, ZSM-5, which is a non-homogeneous acid catalyst having a high acidity in order to increase the activity of the catalyst required for the dehydration reaction. ZSM-5 can be used after conversion to H-ZSM-5 having a hydrogen ion form with a cation according to a known method. For example, when the cation of the basic catalyst ZSM-5 is not a hydrogen ion, it can be prepared by calcining at 450 to 550 ° C for 6 hours or more after ion exchange. On the other hand, the acid sites of the basic catalyst can control the density of Bronsted acid through de-alumina. For this purpose, the basic carrier required for the production can be used by steam treatment at 500 to 700 ° C.

After the conversion to H-ZSM-5, the gallium precursor compound is used as a metal component and the gallium precursor compound having a desired composition is dispersed over a large area in the pores of the catalyst, and supported by calcination . As the gallium introduction method, ion exchange or impregnation may be used, but it is preferable to use an impregnation method which is easy to control the acid sites, especially the target composition. The method of impregnating the gallium precursor with H-ZSM-5 can be performed by, for example, hydrating a gallium precursor into water, impregnating the hydrated solution by adding the prepared H-ZSM-5, removing the solvent at 70 to 90 ° C, Lt; 0 > C for 6 to 24 hours and calcining at 450 to 550 < 0 > C for 6 hours or more. If the calcination temperature is too low, the activity of the catalyst may be deteriorated due to the non-normal metal addition due to the undecomposed precursor, and when the calcination temperature is excessively higher than 550 ° C., It may be difficult to obtain the desired activity of the catalyst.

At this time, the content of gallium introduced is influenced by the specific surface area, strong acid point, cation structure distribution and the like of the finally prepared ethanol dehydration catalyst, and the reaction activity, ethanol conversion and ethylene selectivity, carbon deposition amount, It is important that the optimum range is set. Therefore, in the present invention, it is confirmed that the optimum effect is achieved in the range of 0.05 to 1 wt% based on the weight of the finally produced catalyst, with the content of gallium introduced to dramatically improve both the catalyst property and the catalytic activity, To 0.75 wt%, and most preferably 0.25 to 0.5 wt%. When the gallium content is less than 0.05 wt% or exceeds 1 wt%, the yield in the low-temperature reaction region is unsatisfactory, the carbon deposition amount increases, and it may be difficult to maintain the activity for a long time.

The gallium precursor into, for example, gallium (Ⅱ) chloride (Ga ₂ Cl _4), gallium (Ⅲ) chloride (GaCl _3), gallium oxide (Ga ₂ O _3), anhydride or gallium in a hydrated form (Ⅲ) nitrate _{and; (Ga (NO 3) 3} · n H 2 O n ≥0) may be used, it may be added in amount to suit the final amount of gallium to the desired time of infiltration in the ZSM-5.

The ZSM-5 used as a base catalyst in the present invention preferably has a relatively low Si / Al ₂ molar ratio. This is because when the alumina content is low, that is, when the Si / Al ₂ molar ratio is high, the deactivation proceeds faster in a wide temperature range of 200 to 300 ° C. Also, the impregnated gallium does not reduce the density of the silica, while it can reduce the density of the alumina to greatly limit its activity enhancement. The change of catalytic properties due to the introduction of gallium was confirmed that the ratio of silica was not significantly changed but the ratio of alumina was greatly reduced in the analysis of the element such as XRF (XRF) after the catalyst production. Accordingly, in the present invention, it is preferable to select ZSM-5 having a high density of alumina. Considering the above-mentioned introduction amount of gallium, ZSM-5 having a Si / Al ₂ molar ratio of 20 to 45, preferably 23 to 35, The support can be evenly dispersed and the activity limit can be reduced, so that it is suitable as a support. When the Si / Al ₂ molar ratio is less than 20, the acid amount of the catalyst may increase and the catalyst may be inactivated due to caulking or the like. When the Si / Al ₂ molar ratio exceeds 45, the acid property of the catalyst may not be satisfactory and the ethanol conversion may be lowered.

The ethanol dehydration catalyst according to the present invention may be one prepared by using modified ZSM-5 as a starting catalyst with addition of various metals effective for dehydration. For example, gallium is introduced into ZSM-5 to which lanthanum (La) is added as described in the prior patent application (No. 10-2013-0042846) by the present inventors Can be slightly improved, and can have a favorable effect on maintaining long-term performance. However, in this case, when the total amount of metal added exceeds 1 wt%, the activity of the catalyst may be increased and it may not be effective to maintain stability. Therefore, in the present invention, it is preferable that lanthanum is added so that the total added amount of the metal does not exceed 1 wt% based on the weight of the finally produced catalyst, and it is introduced in an amount of 0.05 to 0.5 wt% considering the preferable gallium content.

The introduction of the lanthanum can be carried out in a similar manner to the above-mentioned introduction of gallium, that is, a method of hydrating a gallium precursor into water, adding ZSM-5 having lanthanum introduced thereto to the hydrated solution, drying and firing the same. At this time, the introduction order of lanthanum and gallium may be changed, and gallium may be introduced first and then lanthanum may be introduced into ZSM-5 into which gallium is introduced. However, when lanthanum and gallium are introduced at the same time without introducing them sequentially, uniform introduction of target elements may not be achieved due to limited mass transfer of the heterogeneous precursor mixture, which is not preferable. When the ion exchange method is used, the introduction order of the target component can be determined by the degree of relative ionization. In the impregnation method, it is preferable to dissolve the precursor in a solvent so that a large number of impurities can be impregnated on the inner surface of the catalyst.

By the lanthanum precursor is, for example, lanthanum chloride (LaCl _3), lanthanum oxide (La ₂ O _3), in the anhydrous or hydrated forms of lanthanum nitrate _{(La (NO 3) 3 ·} n H 2 O; n ≥0) , etc. May be used singly or in combination and may be added in a quantitative manner to the final content of the desired lanthanum when added to ZSM-5.

The ethanol dehydration catalyst according to the present invention described above is a catalyst added to disperse gallium or gallium and lanthanum in an optimum amount in a ZSM-5 support having a high acidity, and as shown in the following Examples and Experimental Examples, When the reaction is carried out under specific reaction conditions, particularly at a low temperature range, the conversion of reactants and the selectivity of ethylene are improved. Addition of a metal component of a specific composition increases the activity of the catalyst and exerts an excellent effect in maintaining the performance. Problems such as use of high temperature energy, low conversion and selectivity, and low catalytic activity in a short period of time, which are problems in the production of ethylene, can be solved.

For example, the ethanol dehydration catalyst according to the present invention may have a carbon deposition amount of less than 1 wt% measured by thermogravimetric analysis (TGA) after dehydration reaction at 240 ° C for 11.5 hours, a space velocity (WHSV) of 5 hr ^-1 And a measured ethanol conversion rate of 99% or more and an ethylene selectivity of 96% or more after dehydration at 240 ° C for 240 hours.

The ethanol dehydration catalyst according to the present invention can be used in a method for producing ethylene by dehydration reaction of a feedstock containing anhydrous ethanol or hydrated ethanol. In the presence of the above-described ethanol dehydration catalyst, Can be reacted at a space velocity (WHSV) of 0.1 to 50 h ^-1 to produce ethylene.

The anhydrous ethanol or hydrous ethanol which can be used as the feedstock is as described above and the feedstock can be supplied in vaporized form through preheating to minimize the large variation of the reaction temperature with latent heat. At this time, nitrogen gas or the like can be used as an inert carrier gas, and can be used in a range that does not affect the performance of the catalyst, specifically, the volume ratio of the vaporized ethanol feedstock to the inert gas is 100 or less have. If the volume ratio is more than 100, the reactant may deviate from the range of mass transfer reaching the catalyst surface.

When the ethanol dehydration catalyst according to the present invention is applied to the dehydration reaction, the reaction temperature may be in the range of 200 to 300 ° C, preferably 220 to 260 ° C. If the reaction temperature is lower than 220 ° C., the reaction can thermodynamically be a dominant side reaction of the production of diethylene ether (DEE) and the conversion rate can be greatly reduced. If the temperature is higher than 260 ° C., the conversion is 100% Proximity One heavy hydrocarbons, including aromatic compounds, may be produced and not suitable for ethylene production.

The space velocity (WHSV) may be in the range of 0.1 to 50 h ^-1 , preferably 0.5 to 10 h ^-1 . The space velocity represents the net mass flow rate of ethanol in the raw material to the catalyst mass applied to the reaction, and can be measured by controlling the initial mass of the catalyst and the feed flow rate of ethanol. If the space velocity is less than 0.1 h ^-1 , the conversion rate may increase but mass production of ethylene may be difficult. If the space velocity is more than 50 h ^-1 , the conversion rate may decrease and the catalyst may be inactivated and the catalyst life may be reduced.

Example 1

15 g of H-ZSM-5 (CBV 3024E, Zeolyst, USA) having a molar ratio Si / Al ₂ of 30 and gallium nitrate hydrate (Ga (NO ₃₎ ₃ were mixed to prepare a _{xH 2 O) (99.9% trace} metal basis, product number 289892, Sigma-Aldrich, USA) in an aqueous solution. At this time, the amount of water to be added to the pores of the catalyst was measured and added. The mixture was then mixed for 20 to 60 minutes and dried in an oven maintained at 80 DEG C for 12 hours. Thereafter, the dried solid matter was pulverized and dried at 200 ° C. for about 1 hour in a firing machine by temperature programming, heated to 550 ° C. and calcined for 6 hours to prepare an ethanol dehydration catalyst.

Example 2

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 0.1 wt%.

Example 3

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 0.25 wt%.

Example 4

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 0.5 wt%.

Example 5

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 0.75 wt%.

Example 6

An ethanol dehydration catalyst was prepared in the same manner as in Example 1 except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 1 wt%.

Example 7

15 g of H-ZSM-5 having a Si / Al ₂ molar ratio of 30 and 10 g of lanthanum nitrate hexahydrate (La (NO ₃ ) ₃ .6H ₂ O) determined to have a lanthanum content of 0.25 wt% (99.99% trace metal basis, product number 331937, Sigma-Aldrich, USA) were prepared and mixed in an aqueous solution. At this time, the amount of water to be added to the pores of the catalyst was measured and added. The mixture was then mixed for 20 to 60 minutes and dried in an oven maintained at 80 DEG C for 12 hours. Thereafter, the dried solid matter was pulverized and dried at 200 ° C. for about 1 hour in a firing machine by temperature programming, heated to 550 ° C. and then calcined for 6 hours to prepare a lanthanum-introduced catalyst. Thereafter, gallium nitrate hydrate quantified so that the gallium content corresponds to 0.25 wt% based on the weight of the catalyst to which the gallium was finally produced was prepared and mixed in the form of an aqueous solution, and then the method described in Example 1 was repeated to produce lanthanum And a gallium-introduced ethanol dehydration catalyst were prepared.

Example 8

An ethanol dehydration catalyst was prepared in the same manner as in Example 7 except that gallium nitrate hydrate was quantitatively determined so as to correspond to a gallium content of 0.5 wt% in Example 7.

Example 9

An ethanol dehydration catalyst was prepared in the same manner as in Example 3, except that H-ZSM-5 (CBV 2314, Zeolyst, USA) having a Si / Al ₂ molar ratio of 23 was used in Example 3.

Comparative Example 1

H-ZSM-5 having Si / Al ₂ molar ratio of 30 was prepared as an ethanol dehydration catalyst.

Comparative Example 2

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantified so that the gallium content in Example 1 was equivalent to 0.02 wt%.

Comparative Example 3

An ethanol dehydration catalyst was prepared in the same manner as in Example 1, except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 1 was equivalent to 1.25 wt%.

Comparative Example 4

An ethanol dehydration catalyst was prepared in the same manner as in Example 7 except that gallium nitrate hydrate was quantitatively determined so that the gallium content in Example 7 was equivalent to 0.75 wt%.

Comparative Example 5

In the same manner as in Example 7 except that lanthanum nitrate hexahydrate was quantitatively determined so that the lanthanum content was equivalent to 0.75 wt% in Example 7 and gallium nitrate hydrate was quantitatively determined so that the gallium content was equivalent to 0.25 wt% A dehydration catalyst was prepared.

Comparative Example 6

An ethanol dehydration catalyst was prepared in the same manner as in Example 3 except that H-ZSM-5 (CBV 5524G, Zeolyst, USA) having Si / Al ₂ molar ratio of 50 was used in Example 3.

Comparative Example 7

An ethanol dehydration catalyst was prepared in the same manner as in Example 3, except that H-ZSM-5 (CBV 8014, Zeolyst, USA) having a Si / Al ₂ molar ratio of 80 in Example 3 was used.

The composition of the ethanol dehydration catalyst according to the above Examples and Comparative Examples is shown in Table 1 below.

Experimental Example 1: Characterization of ethanol dehydration catalyst

(1) Pore analysis of the ethanol dehydration catalyst

In order to confirm the pore characteristics of the ethanol dehydration catalyst according to the present invention, the nitrogen adsorption / desorption experiments of the ethanol dehydration catalysts prepared according to Examples 2, 3, 4 and 7 and Comparative Examples 1, 3 and 4 were carried out. The micropore volume was measured. Table 2 below shows the results of measurement using BET (BELSORP-max, BEL-Japan).

Referring to Table 2, when BET surface area and micropore volume were greatly increased when gallium was introduced at a level of 0.1 wt% in the ethanol dehydration catalyst, it was found that the BET surface area and micropore volume decreased slightly as the gallium content was increased . In addition, when the lanthanum is introduced, the BET surface area and the increase of the micropore volume become much more noticeable, and the BET surface area and the micropore volume decrease as the amount of gallium introduced increases. It is believed that this is due to the partial clogging effect of the catalyst pores. On the other hand, the BET surface area of the prepared catalyst was in the range of 200 to 600 m 2 / g. When the BET surface area is less than 200 m 2 / g, the pore may be seriously clogged due to additives, Lt; 2 > / g, it can be considered that structural destruction occurred during the production process for controlling the catalyst acid sites.

(2) Effect of gallium and lanthanum on crystal structure of ethanol dehydration catalyst

In order to examine the effect of gallium and lanthanum on the crystal structure of the ethanol dehydration catalyst according to the present invention, X-ray diffraction analysis of the ethanol dehydration catalyst prepared according to Examples 3, 4, 6, 7, 8 and Comparative Example 1 XRD, Empyrean, PANalytical, Netherlands), and the results are shown in FIG.

Referring to FIG. 1, no extinction of the intrinsic property peak or other specific peak of H-ZSM-5 (see Comparative Example 1) was found. Therefore, it can be judged that the structure of the ZSM-5 has not been deformed.

Experimental Example 2: Ethylene production yield and catalytic activity analysis by ethanol dehydration reaction using an ethanol dehydration catalyst containing gallium and lanthanum

In order to analyze the production yield of ethylene by the ethanol dehydration reaction using the ethanol dehydration catalyst according to the present invention, the following reaction was carried out.

[Manufacturing reaction example]

The ethanol dehydration reaction was evaluated through a fixed bed reactor. 0.2 g of the catalyst for ethanol dehydration reaction prepared according to Examples and Comparative Examples was charged in a quartz reactor, and nitrogen and ethanol were introduced into the catalyst layer as a reactant to prepare ethylene. Nitrogen was used as a carrier, flow rate was 50 sccm, and ethanol was set at 0.020 ml / min using a HPLC pump (WHSV = 5 hr ^-1 ). The reaction pressure was set at atmospheric pressure. When the reaction temperature was controlled to be constant, dehydration was initiated by supplying ethanol. Ethanol (95% ethanol content) derived from Brazilian sugarcane was used as the raw material. The reaction products flowing out of the reactor were analyzed by time, and quantitated by gas chromatography, which can be analyzed in-line with a 10-port valve. First, the ethanol conversion and the ethylene selectivity of the basic catalyst H-ZSM-5 (Comparative Example 1) were measured according to the reaction temperature, and the results are shown in Table 3. The results are shown in Table 3, Ethanol conversion and ethylene selectivity were measured at a reaction temperature of 240 ° C, and the results are shown in Table 4 below. Here, the ethanol conversion and the ethylene selectivity were calculated according to the following equations (1) and (2). The reaction results were based on the results obtained after 11.5 hours elapsed from the start of the reaction.

First, as shown in Table 3, the results of the search for the reaction temperature of the base catalyst show that H-ZSM-5 having a Si / Al ₂ molar ratio of 30 exhibits the highest ethanol conversion and ethylene selectivity at 260 ° C have. Diethylene ether (DEE) was produced at a reaction temperature of less than 260 ° C., but heavy hydrocarbons including aromatics were predominantly produced at a reaction temperature exceeding 260 ° C.

Table 4 shows the results of the ethanol conversion and ethylene selectivity measurements of the catalysts prepared according to the examples and other comparative examples at a reaction temperature of 240 ° C at which the ethanol conversion and the ethylene selectivity are maintained at 90% Respectively. It can be seen that the conversion and selectivity of ethanol are greatly increased in the case of the catalysts in which gallium is introduced in an amount of 0.05 to 1 wt% (Examples 1 to 6) as compared with H-ZSM-5 (Comparative Example 1) . The activity of the catalysts within this composition range all showed a similar conversion rate of 99% or more, but the selectivity varied according to the composition. In the case of the catalyst containing less than 0.05% by weight of the catalyst into which gallium was introduced (Comparative Example 2), the performance was closer to that of the basic catalyst H-ZSM-5 (Comparative Example 1) In the case of the catalyst (Comparative Example 3), the selectivity of ethylene was greatly decreased, resulting in formation of a heavy hydrocarbon including an aromatic compound. Non-Patent Document 4 and Non-Patent Document 5 disclose that ZSM-5 is used as a starting catalyst and is effective in increasing the selectivity of an aromatic compound when the content of gallium is maintained at 2 wt% or more. In Comparative Example 3 The performance of the catalysts thus prepared is in good agreement with the qualitative characteristics that are distinguished from the performance of the catalysts prepared according to Examples 1 to 6. The above-mentioned prior patent applications of the present inventors have described that the introduction of lanthanum into H-ZSM-5 is effective for the production of ethylene through dehydration of ethanol. Particularly, when 0.25 wt% of lanthanum was introduced, the performance (or yield) and stability (or catalyst life time) were excellent. In order to determine whether the additional introduction of gallium was effective when La-ZSM-5 (0.25 wt%) in which lanthanum was introduced in the optimum composition instead of using H-ZSM-5 (Comparative Example 1) 7 and 8 and Comparative Examples 4 and 5, the performance was evaluated by varying the composition of the metal. (0.25 wt%) La-ZSM-5 (0.25 wt%) as compared with the catalyst prepared with H-ZSM-5 as the starting catalyst (Examples 3 and 4), the selectivity was slightly decreased and the conversion was slightly increased Respectively. In the case of the catalysts (Comparative Examples 4 and 5) in which the content of gallium was increased or the content of lanthanum was increased and the total metal content was introduced to 1 wt% or more, the ethanol conversion and the ethylene selectivity were greatly reduced to 90% or less. This means that for the production of high yield ethylene through dehydration of ethanol, the total content of the introduced metal as well as the optimum combination of ingredients should be controlled.

In order to investigate the effect of the reaction temperature on the two types of catalysts (Examples 3 and 4) which exhibited the best performance among the catalysts using H-ZSM-5 as a starting catalyst and introduced at different gallium contents, 11.5 The ethanol conversion and ethylene selectivity after the reaction were measured and the results are shown in Table 5 below.

As shown in Table 5, in the case of the catalyst in which gallium was introduced in an amount of 0.25% by weight (Example 3), the conversion and selectivity were all found to be 98% or more in the reaction temperature range of 230 to 240 ° C, (Example 4) showed relatively high conversion and selectivity only in a very narrow temperature range near 240 ° C.

H-ZSM-5 and ZSM-5 with a small amount of lanthanum were used as a starting catalyst and gallium was introduced to confirm whether the ethanol dehydration catalyst according to the present invention can produce ethylene in high yield without inactivity for a long time. (Examples 3 and 7), which were found to be the most excellent in the catalyst performance evaluation after 11.5 hours, were used to measure the ethanol conversion and ethylene selectivity over time up to 240 hours after starting the dehydration reaction The long life test of the catalyst was carried out and the results are shown in Table 6 below.

Referring to Table 6, when the ethanol feedstock was fed at a space velocity (WHSV) of 5 hr < ^-1 > using catalysts in which gallium was introduced in the optimum range of contents (Examples 3 and 7) Ethanol conversion of 99% or more and ethylene selectivity of 96 to 98% for 240 hours or more.

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

A method for producing ethylene by dehydration of a feedstock comprising hydrous ethanol derived from carbohydrate, woody or starch based plants and having a moisture content of 30% by weight or less,
Reacting the feedstock at a space velocity (WHSV) of 0.1 to 50 h < ^-1 > at a reaction temperature of 220 to 260 DEG C in the presence of an ethanol dehydration catalyst,
Wherein the total content of the gallium (Ga) and the lanthanum (La) is less than 1% by weight, and the content of gallium (Ga) and lanthanum (La) ,
The ZSM-5 has a Si / Al ₂ molar ratio of 23 to 35,
Wherein the ethylene conversion is at least 99% and the ethylene selectivity is at least 96% as measured under the following conditions.
[Measuring conditions]
Measurement of ethanol conversion and ethylene selectivity after dehydration for 240 hours at a space velocity (WHSV) of 5hr ^-1 and 240 ° C.

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