KR20200116428A - A supported catalyst for non-oxidative dehydrogenation of alkane and method for preparing alkene using the same - Google Patents

Abstract

The present invention relates to a catalyst for dehydrogenation of alkanes and a method for producing alkenes using the same. More specifically, the present invention relates to a catalyst having high catalytic activity and high selectivity to propene in a process of producing propene by dehydrogenation of propane, and a method for producing propene using the same. The catalyst includes a complex metal oxide represented by chemical formula 1: Cu_aZr_(1-a)O_b, and is used in dehydrogenation of alkanes having 2 to 6 carbon atoms.

Description

Catalyst for direct dehydrogenation of alkanes and method for producing alkenes using the same {A SUPPORTED CATALYST FOR NON-OXIDATIVE DEHYDROGENATION OF ALKANE AND METHOD FOR PREPARING ALKENE USING THE SAME}

The present invention relates to a supported catalyst for dehydrogenation of alkanes and a method for producing alkenes using the same.

Alkene compounds such as ethene (ethylene), propene (propylene) and butene, that is, olefin compounds, are widely used in the petrochemical industry as basic materials for synthesis of other compounds or polymers.

For example, in the case of ethylene, it is an olefin compound having the simplest structure, and is used as a basic monomer for the synthesis of polyethylene or other polymers, and is also used for welding or fruit ripening.

Propylene, along with ethylene, is the most basic substance used as a measure of the petrochemical industry. It has a methyl group and an ethylenically unsaturated bond, so it can be converted into various chemical substances. It is mainly used for the production of polypropylene, which is typically a thermoplastic plastic, and is also used as a raw material for acrylonitrile, propylene oxide, epoxy resin, oxo alcohol, and isopropyl alcohol.

In the case of butene, it is used as a copolymerization monomer with ethylene and propylene, or is used in the production of butadiene, which is another major industrial raw material.

In general, these olefin compounds are produced as a by-product in the refining process of crude oil or obtained by the thermal decomposition process of naphtha, but in recent years, in order to meet the high demand in the petrochemical industry, it is also through the dehydrogenation process of lower hydrocarbons using a catalyst. Is being produced.

In particular, in the case of propylene, the use of it as a vehicle or refill material is rapidly increasing, and the demand is increasing.However, since the existing crude oil refining process or naphtha cracking process is mainly concentrated on the production of ethylene, the increase in the supply of propylene is There are restrictions, and technology for diversifying propylene supply is drawing attention.

The dehydrogenation reaction of alkanes is a major reaction capable of producing such an olefin compound, and can be carried out in the presence of a noble metal catalyst or a transition metal catalyst under high temperature and low pressure conditions.

In the case of a noble metal catalyst, it is known that the reaction proceeds by a direct dehydrogenation mechanism in which hydrogen is adsorbed at the active point, and in the case of a transition metal oxide, it is known that the reaction proceeds by a partial oxidation mechanism of the lattice oxygen of the catalyst.

A catalyst such as platinum is known as a noble metal catalyst, and a catalyst in which chromium oxide or vanadium oxide is supported as an active phase on an alumina carrier is known as a transition metal catalyst.

However, there is a problem in that it is difficult to obtain a sufficient yield of propylene without an oxidizing agent with only a single metal, and due to a low surface area, there is a problem that the catalytic activity is easily deteriorated, so that while showing high activity in the reaction, high selectivity for a specific product There is a need for catalyst research.

The present specification is intended to provide a catalyst for dehydrogenation of alkanes, exhibiting high activity in the dehydrogenation reaction of alkanes, and high selectivity for specific alkenes.

In addition, the present specification is to provide a method of preparing an alkene using the catalyst.

The present specification is intended to provide a catalyst, which is used in the dehydrogenation reaction of an alkane having 2 to 6 carbon atoms, including a composite metal oxide represented by the following formula (1).

[Formula 1]

Cu _a Zr _1-a O _b

In Formula 1,

a is greater than or equal to 0, less than 1,

b is greater than or equal to 1 and less than or equal to 2.

In this case, in Formula 1, a is greater than 0 and less than 1, that is, it may be desirable to necessarily include a copper component.

In addition, a is greater than or equal to about 0.01, less than or equal to about 0.3, or greater than or equal to about 0.01, less than or equal to about 0.2, and further comprising a copper component in a specific range of content It may be desirable.

According to an embodiment of the present invention, the composite metal oxide may have a BET surface area value of about 40 m ² /g or more. Specifically, the lower limit may be about 40 m ² /g or more, or about 50 m ² /g or more, or about 60 m ² /g or more, and the upper limit is about 100 m ² /g or less, or about 80 m It may be more desirable to be less than or equal to ² /g, or less than or equal to about 77 m ² /g.

According to another embodiment of the present invention, the composite metal oxide may have a total acidity of about 0.17 mmol/g or less according to NH ₃ -TPD analysis. Specifically, the lower limit may be about 0.001 mmol/g or more, or about 0.05 mmol/g or more, or about 0.07 mmol/g or more, and the upper limit is about 0.17 mmol/g or less, or about 0.16 mmol/g or less, Or less than about 0.15 mmol/g may be more preferred.

In this case, the composite metal oxide may have an acidity of about 0.1 mmol/g or less according to NH ₃ -TPD analysis between 290 °C and 330 °C. Specifically, the lower limit may be about 0.001 mmol/g or more, or about 0.005 mmol/g or more, and the upper limit is about 0.1 mmol/g or less, or about 0.07 mmol/g or less, or about 0.06 mmol/g or less, or It may be more desirable to be less than or equal to about 0.03 mmol/g.

According to another embodiment of the present invention, the composite metal oxide may not include a single CuO phase.

Specifically, when the composite metal oxide is analyzed by an X-ray diffraction spectrum, a peak due to CuO alone may not be observed.

In addition, when the composite metal oxide is analyzed by an X-ray diffraction spectrum, a peak due to tetragonal ZrO2 may be observed.

Meanwhile, the present specification is to provide a catalyst composition comprising the above-described catalyst and a carrier on which the catalyst is supported.

In this case, the carrier may include at least one selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, and zirconium oxide.

On the other hand, the present specification includes the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbons by contacting the above-described catalyst with an alkane having 2 to 6 carbons, carbon It is intended to provide a method for producing a number of 2 to 6 alkenes.

In addition, the present specification includes the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbons by contacting the catalyst composition described above with an alkane having 2 to 6 carbons, It is intended to provide a method of preparing an alkene having 2 to 6 carbon atoms.

In this case, the alkane having 2 to 6 carbon atoms is at least one selected from the group consisting of propane, butane, pentane, and hexane;

The alkene having 2 to 6 carbon atoms may be at least one selected from the group consisting of propene, butane, pentene, and hexene.

According to an embodiment of the present invention, the manufacturing method includes the steps of activating the catalyst using an active gas; And contacting the activated catalyst with an alkane having 2 to 6 carbon atoms.

In addition, the dehydrogenation reaction may be performed at about 300 to about 800 °C, or about 500 to about 700 °C, or about 550 to about 650 °C.

The terms used in the present specification are only used to describe exemplary embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present specification, terms such as "comprise", "include" or "have" are used to describe implemented features, numbers, steps, components, or combinations thereof, and one or more other features, numbers, and steps , Components, combinations or additions thereof are not excluded.

The present invention will be described in detail below and exemplify specific embodiments, as various changes can be made and various forms can be obtained. However, this is not to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present specification, the dehydrogenation reaction of an alkane having 2 to 6 carbon atoms means that hydrogen is adsorbed at the active point of the catalyst, so that two different hydrogens bonded to adjacent carbons of the alkane are removed. As a result, it refers to a direct dehydrogenation reaction in which a double bond is formed between adjacent carbons, which is distinguished from an oxidative dehydrogenation reaction through a partial oxidation mechanism of oxygen located in the lattice of the catalyst.

This direct dehydrogenation reaction can be briefly expressed as the following reaction mechanism.

In the above reaction scheme, R1 and R2 may each independently, be the same as or differently from each other, be hydrogen or an alkyl having 1 to 4 carbon atoms.

Hereinafter, the present invention will be described in detail.

According to an aspect of the present invention, there is provided a catalyst comprising a composite metal oxide represented by the following formula (1) and used in the dehydrogenation reaction of an alkane having 2 to 6 carbon atoms.

[Formula 1]

Cu _a Zr _1-a O _b

In Formula 1,

a is greater than or equal to 0, less than 1,

b is greater than or equal to 1 and less than or equal to 2.

As described above, the direct dehydrogenation of alkanes is a reaction in which hydrogen atoms bonded to adjacent carbons are removed from alkanes to produce an olefin having a carbon double bond.

This direct dehydrogenation reaction, although the reaction mechanism itself is very simple, is a highly endothermic reaction, and is thus thermodynamically disadvantageous. Therefore, in order to increase the yield of alkenes, reaction conditions at a very high temperature are required, and generally, under a temperature condition of about 500 to about 800°C, and a pressure condition of about 0.5 to about 2 atm, metals such as platinum It proceeds in the presence of a catalyst.

However, when a catalyst is used and the temperature is increased to increase the conversion rate, the carbon-carbon bond of the reactant alkanes is broken, and side reactions such as decomposition into smaller alkanes increase as hydrogen is added. There is a problem in that by-products such as coke or tar are rapidly deposited on the carrier, and the activity of the catalyst is rapidly deteriorated.

The inventors of the present invention, when using a metal catalyst of a specific composition, the activity for the dehydrogenation reaction of alkanes is very high, the selectivity for a specific olefin is very high, it is possible to suppress the generation of by-products. Accordingly, it was discovered that high catalytic activity can be stably maintained, and the present invention was completed.

According to an embodiment of the present invention, a catalyst for dehydrogenation of alkane having 2 to 6 carbon atoms includes a composite metal oxide represented by the following formula (1).

[Formula 1]

Cu _a Zr _1-a O _b

In Formula 1,

a is greater than or equal to 0, less than 1,

b is greater than or equal to 1 and less than or equal to 2.

In Formula 1, a is the ratio of copper (Cu) contained in the composite metal oxide, which is greater than or equal to 0 and less than 1. That is, the composite metal oxide may be in the form of a zirconium oxide that does not contain copper, or may be a form of a copper-zirconium composite metal oxide that includes both copper and zirconium.

And, in Formula 1, b is the ratio of oxygen (O) contained in the composite metal oxide, greater than or equal to 1, and less than or equal to 2, in which case, b is, copper contained in the composite metal oxide And the ratio of zirconium and the number of oxidation of each atom of copper and zirconium.

In this case, in Formula 1, a is greater than 0 and less than 1, that is, it may be desirable to necessarily include a copper component.

In addition, a is greater than or equal to about 0.01, less than or equal to about 0.3, or greater than or equal to about 0.01, less than or equal to about 0.2, and further comprising a copper component in a specific range of content It may be desirable.

In the composite metal oxide composition of the catalyst, the zirconium (Zr) component can play a role of providing an active point of the reaction mainly in the above-described dehydrogenation reaction of alkanes.

In the composite metal oxide composition of the catalyst, since the copper (Cu) component generally has a lower oxidation number than zirconium, when incorporated into the zirconium oxide lattice structure, oxygen defects of zirconium oxide may be generated. This oxygen deficiency point can accelerate the formation of zirconium atoms in a coordination bond unsaturated state showing activity against the dehydrogenation reaction of propane, and therefore, the copper component can serve as a kind of cocatalyst.

From this point of view, when the ratio of copper is too high outside the above range, there may be a problem in that the conversion rate of alkanes is lowered by covering the active point of zirconium, and the beneficial effect of the addition of copper may be deteriorated.

On the other hand, when the ratio of the copper is too low, sintering of the metal occurs and coke is easily produced, and thus, a problem in that the catalytic activity decreases may occur.

According to an embodiment of the present invention, the composite metal oxide may have a BET surface area value of about 40 m ² /g or more. Specifically, the lower limit may be about 40 m ² /g or more, or about 50 m ² /g or more, or about 60 m ² /g or more, and the upper limit is about 100 m ² /g or less, or about 80 m It may be more desirable to be less than or equal to ² /g, or less than or equal to about 77 m ² /g.

As described above, the composite metal oxide used as a catalyst according to an aspect of the present invention has a relatively large specific surface area value compared to the conventional alkane dehydrogenation catalyst, and thus has a wide contact area with gas during reaction, It can provide a sufficient reactive active point.

If the BET surface area value is too small, a sufficient active point may not be provided to the catalytically active metal, and thus a problem in that the activity for the reaction is deteriorated may occur.

According to another embodiment of the present invention, the composite metal oxide may have a total acidity of about 0.17 mmol/g or less according to NH ₃ -TPD analysis. Specifically, the lower limit may be about 0.001 mmol/g or more, or about 0.05 mmol/g or more, or about 0.07 mmol/g or more, and the upper limit is about 0.17 mmol/g or less, or about 0.16 mmol/g or less, Or less than about 0.15 mmol/g may be more preferred.

In this case, the composite metal oxide may have an acidity of about 0.1 mmol/g or less according to NH ₃ -TPD analysis between 290 °C and 330 °C. Specifically, the lower limit may be about 0.001 mmol/g or more, or about 0.005 mmol/g or more, and the upper limit is about 0.1 mmol/g or less, or about 0.07 mmol/g or less, or about 0.06 mmol/g or less, or It may be more desirable to be about 0.03 mmol/g or less.

According to another embodiment of the present invention, the composite metal oxide may not include a single CuO phase. In the present specification, the fact that the composite metal oxide does not include a single CuO phase as described above means that all copper (Cu) components in the composite metal oxide form a composite metal oxide crystal together with zirconium, so that the copper oxide alone does not form a crystal. Means not.

This can be confirmed by X-ray diffraction analysis.

Specifically, zirconium oxide is generally known to have a monoclinic structure at room temperature, but monoclinic zirconium oxide (m-ZrO2) is generally 2theta = 28.5 degree (111￣) on the X-ray diffraction spectrum, Specific peaks such as 31.5 degree (111), 34.5 degree (002), 35.5 degree (200), 49.5 degree, and 50.5 degree (122) can be observed.

In the lattice of such pure zirconium oxide, when elements of different sizes or different oxidation numbers are mixed, structural defects (oxygen defect points) are formed, and structural changes in the form of tetragonal occur to stabilize them. . In this case, tetragonal zirconium oxide (t-ZrO2) is typically 2theta = 30.5 degree (101), 35.5 degree (110), 50.5 degree (112), and 60.5 degree (211) on the X-ray diffraction spectrum. Peaks can be observed.

Likewise, when CuO forms a single crystal, in general, according to the X-ray diffraction spectrum, 2theta = 32.5 degree (110), 36 degree (002), 39 degree (111), 49 degree (-202), and 62 degree A specific peak of (-113) can be observed.

In the composite metal oxide used in the catalyst according to an embodiment of the present invention, for the same reason as described above, when the composite metal oxide is analyzed by an X-ray diffraction spectrum, a peak due to CuO alone may not be observed.

However, the measurement may be expressed differently within an error range of about -0.5 degree to +0.5 degree, depending on a measurement condition or an analysis method, and each peak may appear in an overlapping form in a similar range.

In this case, it can be confirmed by the peaks appearing at 2theta = 32.5 degree (110) and 62 degree (-113) among the specific peaks caused by CuO alone, but in the composite metal oxide of the present invention, it is difficult to find such a peak.

In this way, the catalyst according to an embodiment of the present invention has high activity and selectivity in the dehydrogenation reaction of alkanes, because CuO does not exist as a single phase and all forms a composite metal oxide crystal of Cu-Zr-O. You will be able to.

In the direct dehydrogenation reaction of alkanes, the zirconium atom in the unsaturated state of the coordination bond acts as an active point of the reaction. The zirconium atom in the unsaturated state of the coordination bond corresponds to the Lewis acid site when viewed as an acid point, of which the strong acid point rather promotes the formation of coke in the reaction, thereby promoting the activity of the catalyst. Since it can be reduced, the weak acid point serves as the preferred active point of the reaction.

Since the catalyst according to an embodiment of the present invention contains zirconium and copper in a specific ratio, as described above, the catalyst has relatively few strong acid points and relatively large acid point distributions. Accordingly, Can exhibit excellent catalytic activity in direct dehydrogenation of kane.

The composite metal oxide as described above is a sequential impregnation method, a co-precipitation method, and a sol-gel method using salts of these metals as a precursor of the metal. ), etc., can be prepared by a method generally used in the production of metal oxides.

The salt of copper that can be used at this time is a copper oxide containing Cu ₂ O, CuO, Cu ₂ O _3, etc., a halide of copper that may be represented by CuX, or CuX ₂ (X is a halogen element), Hydroxides of copper, nitrates of copper, sulfates of copper, organic acid salts of copper, and the like, and hydrates thereof may also be used.

In addition, the zirconium salt may also include zirconium halides including Cl, Br, I, etc., zirconium hydroxide, zirconium nitrate, zirconium sulfate, or zirconium organic acid salt, and hydrates thereof Can be used.

These precursors may be prepared in the form of a solution using an aqueous solution or other solvent, and for precipitation activation, an acid such as nitric acid, hydrochloric acid, or sulfuric acid, or a base that does not generate metal ions such as ammonia is used, It can also be prepared in a pH-adjusted form.

According to the sequential impregnation method, first, the copper is first precipitated, and after the precipitation is completed, the zirconium may be precipitated again.

Specifically, water or other solvent as a medium for the precipitation reaction is prepared, and nitric acid, hydrochloric acid, or sulfuric acid is optionally added thereto, and then the above-described copper precursor is added and stirred, and the pH is adjusted to about 7 By controlling as above, copper oxide is precipitated.

Separately, a solution prepared by dissolving the above-described zirconium precursor in nitric acid, hydrochloric acid, or sulfuric acid-added water or other solvent was prepared, added to the copper precipitation mixture prepared above, stirred, and then the pH was adjusted to about 7 By controlling the above and forming a precipitate, a composite oxide of copper and zirconium can be obtained.

The solution in which the precipitate is formed is aged at a temperature of about 80° C. to about 150° C. for about 1 hour to about 24 hours, and the precipitate is filtered through filtration, and then washed with distilled water until the pH becomes about 7.

After washing, drying at a temperature of about 80° C. to about 150° C. for about 1 hour to about 24 hours to obtain a powder of a composite metal oxide, optionally, at a temperature of about 500° C. to about 700° C. The firing process may be further performed.

In the case of using the sequential impregnation method, the order of precipitation of copper and zirconium may be reversed, and zirconium may be precipitated first, and copper may be precipitated later.

According to the co-precipitation method, it is possible to proceed by a method in which copper and zirconium are simultaneously precipitated.

Specifically, water or other solvent as a medium for the precipitation reaction is prepared, nitric acid, hydrochloric acid, or sulfuric acid is optionally added thereto, and then the above-described copper precursor and zirconium precursor are respectively added to adjust the concentration, and stirred. After that, the pH is adjusted to about 7 or more to precipitate a composite metal oxide of copper and zirconium.

The solution in which the precipitate is formed is aged at a temperature of about 80° C. to about 150° C. for about 1 hour to about 24 hours, and the precipitate is filtered through filtration, and then washed with distilled water until the pH becomes about 7.

After washing, drying at a temperature of about 80° C. to about 150° C. for about 1 hour to about 24 hours to obtain a powder of a composite metal oxide, optionally, at a temperature of about 500° C. to about 700° C. The firing process may be further performed.

In the case of other sol-gel methods, it is possible to proceed without significantly different from the methods generally used in the technical field to which the present invention belongs, and the present invention is not necessarily limited thereto.

However, among the sequential impregnation method, co-precipitation method, and sol-gel method, in the case of the sequential impregnation method, the copper component is not mixed with the zirconium oxide and is distributed only on the surface of the zirconium oxide, so that the activity of the catalyst does not increase significantly. Problems may occur, and it may be preferable to use a coprecipitation method or a sol-gel method rather than a sequential impregnation method.

Meanwhile, the present specification is to provide a catalyst composition comprising the above-described catalyst and a carrier on which the catalyst is supported.

That is, the above-described composite metal oxide of copper and zirconium, as such, may be used in the dehydrogenation reaction of alkanes, and in terms of improving reaction activity, etc., it may be used in the form of a supported catalyst supported on a carrier. .

In this case, the carrier may include at least one selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, and zirconium oxide.

And, when used as a supported catalyst, the catalyst composition, based on 100 parts by weight of the carrier, about 0.01 to about 10 parts by weight of the composite metal oxide, preferably about 0.1 to about 5 parts by weight, or about 0.5 to about 2 It may include parts by weight.

Such a supported catalyst may be prepared by a method of adding a carrier together during a precipitation reaction in the process of preparing a composite metal oxide such as the sequential impregnation method or coprecipitation method described above.

On the other hand, the present specification includes the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbons by contacting the above-described catalyst with an alkane having 2 to 6 carbons, carbon It is intended to provide a method for producing a number of 2 to 6 alkenes.

In addition, the present specification includes the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbons by contacting the catalyst composition described above with an alkane having 2 to 6 carbons, It is intended to provide a method of preparing an alkene having 2 to 6 carbon atoms.

The dehydrogenation reaction of such alkanes, as described above, may be briefly represented by the following reaction mechanism, and may proceed in a two-step reaction.

First, in the first step, each hydrogen bonded to an alkane having 2 to 6 carbon atoms is aligned with the catalytically active metal, and in any one hydrogen, the bond between carbon and hydrogen is broken, and the hydrogen is Adsorbed on the catalytically active metal, alkenyl radicals can be formed.

In the second step, thereafter, in the other hydrogen, which has been bonded to the adjacent carbon, the bond between carbon and hydrogen is broken, and the hydrogen is adsorbed to the catalytically active metal, forming a double bond between the carbon-carbon.

Then, thereafter, hydrogen adsorbed on the catalytically active metal is released, and the catalyst can be regenerated.

At this time, the alkane having 2 to 6 carbon atoms, alkane having 2 to 6 carbon atoms, propane, butane, pentane, and hex At least one selected from the group consisting of hexane; The alkene having 2 to 6 carbon atoms may be at least one selected from the group consisting of propene, butane, pentene, and hexene, and more preferably, the Alkane having 2 to 6 carbon atoms may be propane, and an alkene having 2 to 6 carbon atoms may be propene.

The alkanes may be in the form of a straight chain or branched chain, and the alkene may also have a straight chain or branched form, depending on the structure of the alkane as a reactant, in this case, the edge portion of the straight or branched chain, or the middle Among the parts, the double bond may be formed anywhere a double bond can be formed.

In addition, the dehydrogenation reaction of the alkanes may proceed at two or more positions in the alkane molecule when the number of carbon atoms in the reactant is 4 or more, and in this case, the product may be produced in the form of diene.

Specifically, when the reactant is butane, 1,3-butadiene may be formed as a product, and when the reactant is pentane, 1,3-pentadiene or 1,4-pentadiene may be formed as a product. And, when the reaction product is hexane, the product is 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2,4-hexadiene, or 1,3,5-hexatriene May be formed.

When such a diene-type compound is formed, the dehydrogenation reaction of the alkane may proceed at the same time at two or more positions in the alkane molecule, or the alkene is first formed by the first reaction, and then sequentially at other sites of the molecule. As a result, the second or third dehydrogenation reaction may proceed.

However, in terms of the reaction activity and selectivity of the catalytically active metal, the reactant is most preferably propane, and accordingly, the product is most preferably propene.

And, specifically, the method of producing an alkene having 2 to 6 carbon atoms includes: activating the catalyst using an active gas; And contacting the activated catalyst with an alkane having 2 to 6 carbon atoms.

In this case, as the active gas, a reducing gas such as carbon monoxide, hydrogen, ethylene, ethane, or methane may be used, and in this case, an inert gas such as nitrogen or a group 18 gas may be used as a carrier gas. Such an active gas may react with oxygen on a highly reactive catalyst surface to activate the catalyst.

This pretreatment may be performed under a temperature condition of about 500 to about 700°C. At this time, the injection amount (Standard Cubic Centimeter per Minute, sccm, cm ³ /min) may proceed at a rate of about 10 to about 100 sccm, or about 20 to about 50 sccm. However, the present invention is not necessarily limited thereto, and this may vary depending on the pretreatment temperature and the amount of catalyst injected into the pretreatment.

Then, after that, by contacting the activated catalyst with an alkane having 2 to 6 carbon atoms, the dehydrogenation reaction may be proceeded.

The dehydrogenation reaction is about 300 to about 800 °C, preferably about 500 to about 700 °C, more preferably about 550 to about 650 °C under a temperature condition, the reaction product inside the reactor containing the catalyst alkanes It may proceed in the form of supplying in gaseous form. When the temperature is too low, there may be a problem in that the activity of the reaction decreases, and when the temperature is too high, a problem in that the decomposition reaction of alkanes used as a reactant proceeds may occur.

And, when supplying, the reactant alkane may be injected using an inert gas such as nitrogen as a carrier gas, and the injection amount may be controlled by a mass flow controller or the like. The amount of reactants injected (Standard Cubic Centimeter per Minute, sccm, cm ³ /min) is based on the total input gas of about 10 to about 100 sccm, or about 20 to about 70 sccm, of which reducing gas: carrier gas It may be desirable to proceed so that the ratio is about 0.01:1 to about 0.3:1. However, the present invention is not necessarily limited to these conditions, and it may be adjusted differently depending on the amount of catalyst input, the type of reactant, the reaction temperature, and the specific composition of the catalyst.

The catalyst for dehydrogenation of alkanes according to an aspect of the present invention has high activity for dehydrogenation of alkanes, can maintain high activity for a long time, and exhibits high selectivity for specific alkenes.

Therefore, when producing an alkene using the catalyst according to an aspect of the present invention, it is possible to achieve a higher yield than the conventional.

1 is an XRD analysis spectrum of a composite metal oxide used in a catalyst according to an embodiment of the present invention.
2 is a spectrum obtained by analyzing an acid point of a composite metal oxide used in a catalyst according to an embodiment of the present invention.
3 is an ammonia elevated temperature desorption analysis spectrum of a composite metal oxide used in a catalyst according to an embodiment of the present invention.
4 is a graph summarizing the yield and selectivity of propene in the method for producing an alkene according to an embodiment of the present invention.

Hereinafter, the functions and effects of the invention will be described in more detail through specific embodiments of the invention. However, these embodiments are only presented as examples of the invention, and the scope of the invention is not determined thereby.

<Example>

Preparation of composite metal oxide

Example 1:

ZrO(NO ₃ ) ₂ was dissolved as a zirconium precursor in 200 ml of distilled water to prepare an aqueous solution having a concentration of 0.1 M.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours to prepare zirconium oxide.

Example 2:

ZrO(NO ₃ ) ₂ was used as a zirconium precursor, and Cu(NO ₃ ) ₂ 3H ₂ O was used as a copper precursor.

A zirconium precursor (0.095 M) and a copper precursor (0.005 M) were dissolved in 200 ml of distilled water to prepare an aqueous solution of 0.1 M based on metal cations.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours, and a copper-zirconium composite metal oxide Was prepared.

Example 3:

ZrO(NO ₃ ) ₂ was used as a zirconium precursor, and Cu(NO ₃ ) ₂ 3H ₂ O was used as a copper precursor.

A zirconium precursor (0.092 M) and a copper precursor (0.008 M) were dissolved in 200 ml of distilled water to prepare an aqueous solution of 0.1 M based on a metal cation.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours, and a copper-zirconium composite metal oxide Was prepared.

Example 4:

ZrO(NO ₃ ) ₂ was used as a zirconium precursor, and Cu(NO ₃ ) ₂ 3H ₂ O was used as a copper precursor.

A zirconium precursor (0.090 M) and a copper precursor (0.010 M) were dissolved in 200 ml of distilled water to prepare an aqueous solution of 0.1 M based on metal cations.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours, and a copper-zirconium composite metal oxide Was prepared.

Example 5:

ZrO(NO ₃ ) ₂ was used as a zirconium precursor, and Cu(NO ₃ ) ₂ 3H ₂ O was used as a copper precursor.

A zirconium precursor (0.085 M) and a copper precursor (0.015 M) were dissolved in 200 ml of distilled water to prepare an aqueous solution of 0.1 M based on a metal cation.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours, and a copper-zirconium composite metal oxide Was prepared.

Example 6:

ZrO(NO ₃ ) ₂ was used as a zirconium precursor, and Cu(NO ₃ ) ₂ 3H ₂ O was used as a copper precursor.

A zirconium precursor (0.075 M) and a copper precursor (0.025 M) were dissolved in 200 ml of distilled water to prepare an aqueous solution of 0.1 M based on a metal cation.

An aqueous ammonia solution (concentration: 28 to 30 wt% based on NH ₃ ) was slowly added dropwise thereto, and the pH was adjusted to 9 to proceed with the precipitation reaction.

The mixture solution in which the precipitate was formed was sealed, and left at about 373 K for about 12 hours, after which it was filtered to filter out the precipitate.

The obtained precipitate was washed several times with distilled water until the pH reached 7, transferred to an oven, dried at about 383 K for about 12 hours, and then calcined again at about 873 K for 3 hours, and a copper-zirconium composite metal oxide Was prepared.

The composite metal oxide prepared in the above example was subjected to XRD analysis.

Cu content ratio analysis:

For the composite metal oxide prepared in the above example, an ICP-OES (inductively coupled plasma-optical emission spectroscopy) analysis was performed using an ARCOS FHM22 device manufactured by SPECTRO.

Surface area analysis:

For the composite metal oxide prepared in the above example, the BET surface area was measured using an ASAP2010 instrument manufactured by Micromeritics.

Scattered point analysis:

With respect to the composite metal oxide prepared in the above example, NH ₃ -TPD analysis was performed using a Belcat II instrument manufactured by MicrotracBEL.

The analysis results are summarized in Table 1 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Cu content (mol%) 0 5.2 7.6 11 16 27 BET surface area (m ² /g) 42 62 72 77 75 60 mountain
point
minute
three Peak 1 0.024 0.028 0.021 0.028 0.032 0.029 Peak 2 0.063 0.086 0.096 0.087 0.067 0.040 Peak 3 0.065 0.017 0.022 0.014 0.020 0.008 Peak1+2 0.087 0.114 0.117 0.115 0.099 0.069 Total Acidity 0.152 0.131 0.139 0.129 0.119 0.077

1 is an XRD analysis spectrum of a composite metal oxide used in a catalyst according to an embodiment of the present invention.

Referring to Figure 1, it can be seen the elemental composition of the composite metal oxide used in the catalyst according to an embodiment of the present invention.

Specifically, zirconium oxide is generally known to have a monoclinic structure at room temperature, and this structure can be confirmed by the m-ZrO2 related peak in FIG. 1.

When elements of different sizes or different oxidation numbers are incorporated in the lattice of such pure zirconium oxide, structural defects (oxygen defect points) are formed, and structural changes in the form of tetragonal occur to stabilize them. This can be confirmed by the t-ZrO2 related peak in FIG. 1.

In the case of FIG. 1, the XRD peak related to CuO is not observed, which means that the copper component is well dispersed on the zirconium oxide.

2 is a spectrum obtained by analyzing an acid point of a composite metal oxide used in a catalyst according to an embodiment of the present invention.

Referring to Figure 2, it can be seen the acid point distribution of the composite metal oxide used in the catalyst according to an embodiment of the present invention.

The acid point of the catalyst is divided into a Bronsted acid point and a Lewis acid point.In general, a zirconium atom in a coordination bond unsaturated state due to the formation of an oxygen defect point is known as a Lewis acid point, and such a Lewis acid point is a dehydrogenation reaction. Serves as the active point of the.

Referring to FIG. 2, in the case of the composite metal oxide used in the present invention, it can be seen that the catalyst has only Lewis acid points even after copper is incorporated.

3 is an ammonia elevated temperature desorption analysis spectrum of a composite metal oxide used in a catalyst according to an embodiment of the present invention.

Referring to FIG. 3, the acid point of the composite metal oxide used in the catalyst according to an embodiment of the present invention can be analyzed.

In NH3-TPD analysis, ammonia, which is a basic substance, is adsorbed on the surface of the catalyst, and then ammonia is desorbed while raising the temperature at a constant rate, and the acid point intensity on the catalyst is evaluated based on the desorption temperature, and It is an analytical method that measures the number.

Referring to FIG. 3, in the case of the composite metal oxide used in the catalyst according to an embodiment of the present invention, as copper is added, the number of strong acid points at which ammonia is desorbed at a high temperature rapidly decreases, and a low temperature It can be clearly seen that the number of weak acid points desorbed from is increasing.

Comparative Example 1

The precursor of platinum (Pt) is Chloroplatinic acid hexahydrate (H ₂ PtCl ₆ xH ₂ O, Sigma-aldrich, ~38% Pt basis), and the precursor of tin (Sn) is Tin chloride dihydrate (SnCl ₂ 2H ₂ O Sigma- aldrich) was used.

As a carrier, γ-Al ₂ O ₃ (Sasol Puralox Scca 5/150) was used.

Distilled water was used as the supported solvent.

A catalyst was prepared such that the amount of Pt supported was 0.5 wt% and the amount of Sn supported was 1.5 wt% based on 1 g of the support.

After completely dissolving the amount of Pt and Sn precursor derived by inverse calculation based on the amount supported in distilled water corresponding to the pore volume of the catalyst, dropwise dropwise mixing was performed on the Al ₂ O ₃ . (using the incipient wetness impregnation method)

This was transferred to an oven, dried at about 110° C. for about 12 hours, and then calcined for about 3 hours under an air atmosphere at a temperature of about 600° C. to prepare a Pt/Al ₂ O ₃ catalyst.

Comparative Example 2

Chromium nitrate nonahydrate (Cr(NO ₃ ) ₃ 9H ₂ O, 99% ACROS) was used as a precursor of chromium (Cr), except that it was 5 wt% based on Cr based on 1 g of the carrier, the same as in Comparative Example 1 By the method, a catalyst was prepared.

Preparation of propene through dehydrogenation of propane

Using the catalysts prepared in Examples and Comparative Examples, propane dehydrogenation was performed by the following method.

First, 0.03 g of quartz wool, 0.2 g of the supported catalyst, was charged in a quartz reactor having an inner diameter of 0.8 cm and a length of 50 cm.

First, argon gas was injected into the reactor while heating the reactor at a constant rate to 873 K for about 60 minutes. (30 sccm)

After the reactor temperature reached 873 K, a mixed gas of hydrogen (5 sccm) and argon (45 sccm) was supplied for about 60 minutes to activate the catalyst, followed by purging with argon gas for about 15 minutes.

Under the conditions of 873 K and atmospheric pressure, a mixture gas of propane (8 sccm) and argon (52 sccm) was injected into the reactor, while propane dehydrogenation was performed.

The reaction proceeded for about 30 minutes, and the product was analyzed over time after the start of the reaction to confirm the decrease in catalytic activity according to the progress of the reaction.

The product was analyzed through gas chromatography (YL6500 GC) equipped with a flame ionization detector (FID).

Through FID, products such as methane, ethane, ethene, propane, and propene were analyzed, and through this, the propene conversion rate, propene selectivity, and propene yield were calculated. (Unit: mol%)

The analysis results are summarized in Tables 2, 3, 4 and 4 below.

Propylene yield (%) Example 1
(0) Example 2
(5) Example 3
(8) Example 4
(10) Example 5
(15) Example 6
(25) 5 minutes 21.3 25.7 26.1 26.2 22.7 21.0 11 minutes 15.4 17.8 18.2 18.2 16.4 14.0 17 minutes 11.7 12.8 13.5 13.4 12.1 9.9 23 minutes 9.3 10.0 10.5 10.3 9.4 7.4 29 minutes 7.3 7.9 8.3 8.0 7.2 5.6

Propane Conversion Rate (%) Example 1
(0) Example 2
(5) Example 3
(8) Example 4
(10) Example 5
(15) Example 6
(25) 5 minutes 21.7 26.1 26.5 26.6 23.0 21.3 11 minutes 15.7 18.0 18.5 18.4 16.6 14.2 17 minutes 11.9 13.0 13.7 13.6 12.3 10.1 23 minutes 9.5 10.2 10.7 10.5 9.6 7.5 29 minutes 7.5 8.1 8.5 8.2 7.4 5.7

Propylene selectivity (%) Example 1
(0) Example 2
(5) Example 3
(8) Example 4
(10) Example 5
(15) Example 6
(25) 5 minutes 98.6 98.4 98.5 98.6 98.7 98.6 11 minutes 98.5 98.6 98.7 98.6 98.7 98.5 17 minutes 98.2 98.3 98.5 98.4 98.4 98.2 23 minutes 97.9 97.9 98.2 98.0 98.1 97.8 29 minutes 97.5 97.6 98.0 97.7 97.7 97.3

Referring to the above table and FIG. 4, it can be clearly confirmed that the catalyst according to an embodiment of the present invention has high catalytic activity and high selectivity to propene in the production of propene. In the case of the catalyst according to an embodiment, it can be seen that even though it is a bulk catalyst, it exhibits a better effect than the existing supported catalyst.

In addition, the platinum catalyst or chromium catalyst used in the past is very expensive and has an adverse effect on the environment. It is thought that it can replace environmental limitations.

Claims (15)

A catalyst comprising a composite metal oxide represented by the following formula (1) and used in the dehydrogenation reaction of an alkane having 2 to 6 carbon atoms:
[Formula 1]
Cu _a Zr _1-a O _b
In Formula 1,
a is greater than or equal to 0, less than 1,
b is greater than or equal to 1 and less than or equal to 2.
The method of claim 1,
Wherein a is greater than 0 and less than 1, the catalyst.
The method of claim 1,
Wherein a is greater than or equal to 0.01 and less than or equal to 0.3.
The method of claim 1,
The composite metal oxide has a BET surface area value of 40 m ² /g or more.
The method of claim 1,
The composite metal oxide has a total acidity of 0.17 mmol/g or less according to NH ₃ -TPD analysis, a catalyst.
The method of claim 1,
The composite metal oxide has an acidity of 0.1 mmol/g or less according to NH ₃ -TPD analysis between 290°C and 330°C.
The method of claim 1,
The composite metal oxide does not contain a CuO single phase, a catalyst.
The method of claim 1,
When the composite metal oxide is analyzed by an X-ray diffraction spectrum, a peak due to tetragonal ZrO2 is observed.
A catalyst composition comprising the catalyst according to claim 1 and a carrier on which the catalyst is supported.
The method of claim 9,
The carrier, a catalyst composition comprising at least one selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, and zirconium oxide.
The catalyst according to claim 1, comprising the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbons by contacting an alkane having 2 to 6 carbons, Method for producing 6-member alkene.
The catalyst composition according to claim 9, comprising the step of conducting a dehydrogenation reaction of an alkane having 2 to 6 carbon atoms by contacting an alkane having 2 to 6 carbon atoms. A method for producing an alkene of to 6.
The method of claim 11 or 12,
Alkane having 2 to 6 carbon atoms is at least one selected from the group consisting of propane, butane, pentane, and hexane;
The alkene having 2 to 6 carbon atoms is at least one selected from the group consisting of propene, butane, pentene, and hexene, alkenes having 2 to 6 carbon atoms ( alkene).
The method of claim 11 or 12,
Activating the catalyst using an active gas; And
A method for producing an alkene having 2 to 6 carbons, comprising the step of contacting an activated catalyst with an alkane having 2 to 6 carbons.
The method of claim 11 or 12,
The dehydrogenation reaction is carried out at 300 to 800 °C, a method for producing an alkene having 2 to 6 carbon atoms.

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