KR20170068876A - Dehydrogenation Catalysts Having Metal Clusters Encapsulated on Titania and Process For Preparation Thereof - Google Patents

Abstract

The present invention relates to a dehydrogenation catalyst containing metal clusters in titania and a process for their preparation. Specifically, the present invention comprises an alumina support, a titania layer coated on the alumina support, and a hydrogen active metal cluster encapsulated through reduction of the titania layer, wherein the chemical adsorption amount of hydrogen according to temperature is 0.1 < H / M ₃₂₃ ] / [H / M ₅₇₃ ] < 1. Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts represent the adsorption temperature (K).

Description

TECHNICAL FIELD [0001] The present invention relates to a dehydrogenation catalyst containing metal clusters in titania, and a process for producing the dehydrogenation catalyst.

The present invention relates to a dehydrogenation catalyst containing metal clusters in titania and a process for their preparation.

In recent years, prices of olefins, which are raw materials for various petrochemical products, are skyrocketing in the petrochemical market. Of these, light olefins are used in a wide variety of synthetic rubber and copolymer containing n-butene, 1,3-butadiene, isobutene, etc., and their demand and value are increasing mainly in China have.

A method for obtaining such a light olefin is largely obtained by naphtha cracking, and there is a method of direct dehydrogenation of n-butane and the like. However, through the naphtha cracking, C ₄ The mixture is obtained from crude oil and is directly influenced by oil prices. Therefore, there is a problem that it is difficult to cope with changes in market conditions in response to an increasing demand. For this reason, the reaction of obtaining n-butene and 1,3-butadiene by dehydrogenating hydrogen from n-butane or n-butene or obtaining isobutene by dehydrogenation of isobutane is a recent reaction of n-butene , 1,3-butadiene, and isobutene.

Precious metal catalysts such as platinum are widely used as catalysts for the direct dehydrogenation reaction of n-butane. However, since platinum alone can not control many side reactions such as carbon deposition and decomposition, isomerization, aromatization and oligomerization of hard paraffin, various kinds of promoters and supports have been studied.

Supports for platinum-based catalysts known to be effective for the production of butenes by direct dehydrogenation of n-butane have been described by alumina supports [McNamara, J. M. Jackson, S. D. Lennon, Catal. Today, Vol. 81, p. 583 (2003)], Spinel series supports synthesized by adding magnesium or zinc to alumina to alleviate the acidity of alumina [S. Bocanegra, A. Ballarini, P. Zgolicz, O. Scelza, S. de Miguel, Catal. Today, Vol. 143, p. 334 (2009)], a support in which an alkali metal is added to alumina such as sodium-alumina [S. de Miguel, S. Bocanegra, J. Vilella, A. Guerrero-Ruiz, O. Scelza, Catal. Lett. 119, p. 5 (2007)], and supports synthesized with alumina such as zirconium [C. Larsen, J. M. Campos-Martin, J. L. G. Fierro, Langmuir Vol. 16, p. 10294 (2000)]. As the cocatalyst, there is a tin which lowers the adsorption energy of the coke precursor adsorbed on the platinum surface [A. Bocanegra, S. R. de Miguel, A. A. Castro, O. A. Scelza, Catal. Lett. (Liu Jinxiang, Gao Xiuying, Zhang Tao, Lin Liwu, Thermochim., Vol. 96, 129 (2004)). Acta 179, p.9 (1991)].

Despite the various catalysts described above, there is a need in the art for a dehydrogenation catalyst that still exhibits improved catalytic activity, and by this demand, the inventors have found that, even in the presence of impurities such as sulfur, Were investigated for the SMSI catalysts of platinum and titania.

As a result, in the dehydrogenation reaction of a hard alkane requiring a high temperature through the SMSI of platinum and titania, a catalyst which suppresses the hydrogenolysis of the CC bond, which is a side reaction for generating methane and ethane, while maintaining the dehydrogenation reaction, is invented , And found that by controlling the amount of titania, the selectivity of alkene by dehydrogenation is higher than that of conventional catalysts using platinum and tin.

In a specific example according to the present invention, there is provided a dehydrogenation catalyst having activity distinguishable from existing catalysts by controlling the amount of titania contained in the catalyst as a catalyst using a metal cluster and SMSI of titania, and a process for producing the same .

In addition, embodiments of the present invention provide a dehydrogenation catalyst having high dehydrogenation activity and inhibiting cleavage of C-C bond and having excellent thermal stability, and a method for providing the dehydrogenation catalyst.

According to a first aspect of the present invention,

Alumina support;

A titania layer coated on said alumina support; And

A hydrogen activated metal cluster encapsulated through reduction of the titania layer;

And a dehydrogenation catalyst having a chemical adsorption amount of hydrogen according to a temperature satisfying the following relationship:

0.1 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <1

Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts represent the adsorption temperature (K).

In one embodiment of the present invention, the relationship is 0.3 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <0.8.

In one embodiment of the present invention, the content of the titania layer is 2 to 20% by weight, based on the weight of the alumina support coated with the titania layer.

In one embodiment of the present invention, the content of the titania layer is 6 to 10% by weight based on the weight of the alumina support coated with the titania layer.

In one embodiment of the present invention, the hydrogen-active metal is at least one metal selected from Group IB, Group VIIB and Group VIII metals in the periodic table.

In one embodiment of the present invention, the diameter of the hydrogen-activated metal clusters is 0.5 to 50 nm.

In one embodiment of the present invention, the content of the hydrogen-active metal is 0.5 to 1.5% by weight based on the total weight of the dehydrogenation catalyst.

According to a second aspect of the present invention,

(a) dissolving a Ti precursor in deionized water and then adding an alumina support to coat the alumina support with titania; And

(b) providing a hydrogen-active metal precursor to the alumina support coated in step (a), and encapsulating the hydrogen-active metal clusters through reduction of titania, wherein the amount of chemical adsorption of hydrogen according to temperature is expressed by the following relationship Of the dehydrogenation catalyst.

0.1 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <1

Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts represent the adsorption temperature (K).

In one embodiment of the present invention, in the step (a), the Ti precursor is titanium oxysulfate, and the Ti precursor content is in the range of 0.1 to 5 wt% based on the weight of the alumina support coated with titania, 2 to 20% by weight.

In one embodiment of the present invention, the content of the hydrogen-active metal precursor in the step (b) is adjusted so that the content of the hydrogen-active metal is 0.5 to 1.5% by weight based on the total weight of the dehydrogenation catalyst.

In one embodiment of the present invention, the reduction of titania in the step (b) is performed by heat treatment at 300 to 800 ° C under a hydrogen atmosphere.

In one embodiment of the present invention, the step (a)

(a1) dissolving the Ti precursor in deionized water and then adding an alumina support;

(a2) stirring the solution to which the alumina support is added in step (a1) at 30 to 50 DEG C for 20 to 30 hours;

(a3) filtering the stirred solution in step (a2) and washing the filtered alumina support with deionized water and a KOH solution; And

(a4) drying the alumina support washed in step (a3), and calcining the dried alumina support at 300 to 500 DEG C for 1 to 3 hours;

.

According to a third aspect of the present invention,

There is provided a dehydrogenation method for producing an alkene from an alkane in the presence of a catalyst produced according to the process for producing the dehydrogenation catalyst.

In one embodiment of the present invention, the alkane and the alkene have 3 or 4 carbon atoms.

In one embodiment of the present invention, the dehydrogenation process is carried out at 500 to 800 ° C., and the molar ratio of hydrogen / alkane fed to the dehydrogenation process is 0.1 to 10.

The dehydrogenation catalyst provided according to an embodiment of the present invention has reaction characteristics distinct from conventional metal-supported catalysts in which hydrogen active metal clusters are surrounded by titania coated on an alumina support to cause reactions on metal surfaces. This reaction characteristic can be explained by the metal cluster and the SMSI of titania, which suppresses the disruption of the C-C bond, a side reaction of methane and ethane, while maintaining the dehydrogenation reactivity in the dehydrogenation reaction of the light alkane. Based on these basic characteristics, it is possible to control the amount of titania contained in the catalyst to exhibit higher selectivity of alkene by dehydrogenation than a conventional catalyst using a conventional platinum and tin, to prevent sintering of the metal, Excellent thermal stability can be secured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a method for producing a catalyst of the present invention. FIG.
FIG. 2 is a graph showing the activity against butane of a catalyst prepared by adjusting the amount of titania (4, 8, 10, 20 wt%). Specifically, FIG. 2A is a graph showing the conversion of butane according to the reaction time, and FIG. 2B is a graph showing the selectivity of butene, which is a target product of the present invention, according to the reaction time. Also, FIGS. 2C and 2D are graphs showing the selectivity for the hydrocracking reaction and the isomerization reaction, which may appear as side reactions, respectively, according to the reaction time.
3 is a graph showing the dehydrogenation evaluation results of propane and the results of regeneration experiments after the regeneration procedure of the catalysts deactivated by carbon deposition. Specifically, FIG. 3A is a graph showing the conversion of propane after the regeneration procedure for the PtSn / Al ₂ O ₃ catalyst according to the reaction time, and FIG. 3B is a graph showing the propene selectivity for the PtSn / Al ₂ O ₃ catalyst according to the reaction time. FIG. 3C is a graph showing the conversion of propane after the regeneration procedure with respect to the Pt-8TiO ₂ / Al ₂ O ₃ catalyst according to the reaction time, and FIG. 3D is a graph showing the propene selectivity with respect to the reaction time.
FIG. 4 is a graph showing the results after a 400 minute evaluation of each cycle by comparing a Pt-8TiO ₂ / Al ₂ O ₃ catalyst with a PtSn / Al ₂ O ₃ catalyst. Specifically, FIG. 4A is a graph showing the conversion of propane versus reaction time, and FIG. 4B is a graph showing selectivity of propene in reaction time.

The present invention can be achieved by the following description. The following description should be understood to describe preferred embodiments of the present invention, but the present invention is not necessarily limited thereto. It is to be understood that the accompanying drawings are included to provide a further understanding of the invention and are not to be construed as limiting the present invention. The details of the individual components may be properly understood by reference to the following detailed description of the related description.

The terms used in this specification can be defined as follows.

"Hydrogen-active metal" means a metal that is broadly capable of forming hydrogen activated by contact with molecular hydrogen, i.e., dissociated hydrogen.

"Dehydrogenation" refers to a reaction in which hydrogen in a compound is removed. According to an embodiment of the present invention, the dehydrogenation reaction may proceed with the use of a light alkane such as propane and butane as a reactant, and the reaction may result in butene and propene.

"C-C hydrogenolysis" means a reaction in which a single bond between carbon and carbon is cleaved by hydrogen. According to the embodiment of the present invention, a C-C hydrogenation decomposition reaction may occur as a side reaction of the dehydrogenation reaction, and since a light alkane is used as a reactant, methane, ethane, etc. may be generated as a product of the C-C hydrogenolysis reaction.

"Strong Metal-Support Interaction (SMSI)" means strong metal-support interaction. Specifically, the support can interact with the active material, and the interaction of the oxidant with the metal capable of reducing at high reducing temperatures is generally termed "Strong Metal-Support Interaction (SMSI) &quot;. The SMSI can affect the activity of the metal particle / support catalyst in many applications.

The dehydrogenation catalyst provided according to an embodiment of the present invention has a structure in which titania is coated on an alumina support and a cluster of the hydrogen-active metal (M) is contained therein through reduction of the coated titania.

The amount of chemical adsorption of hydrogen in the present specification can be measured using a volumtric method known in the art. When the amount of hydrogen chemical adsorption is measured by a method other than the volumetric method, for example, a pulsing method, there is a limit to actually observe an increase in the amount of chemical adsorption of hydrogen depending on the temperature. This is because the equilibrium time is not sufficient in the pulse method. That is, since the rate at which hydrogen diffuses into the inside of the catalyst is not sufficiently fast even at a high temperature, it is difficult to confirm the increase in the amount of chemical adsorption in the case of measuring the hydrogen while flowing in the form of a pulse in the form of a catalyst as in the pulse method.

The dehydrogenation catalyst provided according to the embodiment of the present invention shows a tendency that the amount of chemical adsorption of hydrogen increases as the temperature increases. Specifically, in the dehydrogenation catalyst, the chemical adsorption characteristic of hydrogen according to the temperature can be expressed by the following relationship:

0.1 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <1

Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts represent the adsorption temperature (K).

In a typical hydrogenation catalyst in which the metal is exposed to the outside, kinetic energy of adsorbed molecules increases with an increase in adsorption temperature, resulting in a typical characteristic that the amount of chemical adsorption decreases. The reason why the dehydrogenation catalyst according to the embodiment of the present invention exhibits hydrogen adsorption characteristics different from the behavior of the catalyst generally predicted is that it is difficult for hydrogen molecules to diffuse into the reduced titania at a low temperature (less than 323 K) It can be explained that the molecules can diffuse into the interior of the catalyst. The value of [H / M ₃₂₃ ] / [H / M ₅₇₃ ] may be determined according to the degree of coating of the titania layer reduced to the hydrogen active metal. According to one embodiment of the present invention, [H / M ₃₂₃ ] / [H / M ₅₇₃ ] may have a value between 0.1 and 1, more specifically between 0.3 and 0.8 . The reason for limiting the measured temperature of the above formula [H / M] to 323K and 573K is 323K is because it corresponds to the general chemical adsorption temperature in the art, 573K is a reversible hydrogen to the TiO ₂ surface, if it exceeds the temperature This is because the adsorption site is generated and the amount of chemical adsorption can not be explained only by chemical adsorption onto the surface of the hydrogen active metal. Therefore, the characteristics of the dehydrogenation catalyst in which the hydrogen-active metal is encapsulated by the titania layer using the formula [H / M ₃₂₃ ] / [H / M ₅₇₃ ], which can indicate the chemical adsorption of the hydrogen active metal surface with respect to the titania layer .

In the embodiment of the present invention, the amount of chemical adsorption of hydrogen according to the temperature of the exemplary Pt-8TiO ₂ / Al ₂ O ₃ catalyst can be represented as shown in Table 1 below.

The amount of chemical adsorption of hydrogen according to the temperature of Pt-8TiO ₂ / Al ₂ O ₃ Temperature (K) 323 373 473 573 673 Of hydrogen
Chemical adsorption amount (H / Pt) 0.23 0.22 0.24 0.39 0.42

According to Table 1, the exemplary Pt-8TiO ₂ / Al ₂ O ₃ catalyst has a value of [H / Pt ₃₂₃ ] / [H / Pt ₅₇₃ ] of about 0.59.

The dehydrogenation catalyst prepared according to embodiments of the present invention can be represented in the following form:

_{M-xTiO 2 / Al 2 O} 3

In the above formula, M represents hydrogen active metal, TiO ₂ represents titania, and Al ₂ O ₃ represents alumina. "TiO ₂ / Al ₂ O ₃ " refers to a form coated with titania on alumina, and "M-TiO ₂ " means that a hydrogen active metal and titania are bonded via SMSI. X represents the content of titania in the catalyst, and the catalyst contains x% by weight of titania, based on the total weight of the titania coated alumina support. For example, according to the above formula, a catalyst obtained by coating 8% by weight of titania based on the total weight of the alumina support coated with titania on an alumina support and supporting Pt with hydrogen active metal inside titania through reduction is Pt- 8 TiO ₂ / Al ₂ O ₃ .

According to one embodiment of the present invention, the content of the hydrogen-active metal may range from about 0.01 to 10% by weight, specifically from about 0.1 to 2% by weight, more specifically from about 0.5 to 1.5% by weight, have. If the content of the hydrogen-active metal is less than about 0.01% by weight based on the weight of the entire catalyst, the reactivity of the dehydrogenation reaction by the hydrogen-active metal may be significantly lowered. On the other hand, when the content of the hydrogen-active metal is more than about 10% by weight based on the weight of the entire catalyst, it contains a relatively large amount of hydrogen-active metal as compared with titania, The reactivity of other hydrogenation reactions such as hydrogenation reaction, hydrogenation deoxygenation reaction, hydrogenation denitration reaction, hydrogenation desulfurization reaction, hydrogenation isomerization reaction, dehydrogenation reaction and the like becomes high and the selectivity of alkene due to dehydrogenation reaction is lowered The benefit of the dehydrogenation reaction due to the increase in weight can be reduced.

The hydrogen-active metal is a metal having hydrogen activity capable of generating alkene through dehydrogenation reaction when an alkane is used as a reactant, and one or more metals selected from Group IB, Group VIIB and Group VIII metals in the periodic table However, the present invention is not limited thereto. According to one embodiment of the present invention, the hydrogen-active metal may be one or more metals selected from the group consisting of Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Pt may be used as the hydrogen-active metal. The hydrogen-active metal is encapsulated and dispersed in a titania layer reduced by the reduction of titania, and is present in a cluster form. According to one embodiment of the present invention, the diameter of the metal clusters may range from about 0.5 to 50 nm, specifically about 0.5 to 10 nm, more specifically about 0.5 to 2 nm.

According to one embodiment of the present invention, the content of titania is in the range of about 2 to 20 wt%, specifically about 4 to 12 wt%, more specifically about 6 to 10 wt%, based on the total weight of the titania coated alumina support % &Lt; / RTI &gt; If the content of titania is less than about 2 wt.% Based on the total weight of the alumina support coated with titania, a relatively small amount of titania is contained in comparison with the hydrogen active metal, so that the bonding of the hydrogen active metal and titania through SMSI And if the content of titania is greater than about 20% by weight based on the total weight of the alumina support coated with titania, the reduced titania layer surrounding the active metal becomes thicker and the dehydrogenation reaction of the hydrogen- Activity may be significantly reduced.

According to another embodiment of the present invention, there is provided a method of preparing a dehydrogenation catalyst, comprising dissolving a Ti precursor in deionized water, adding an alumina support to the alumina support, Coating the support with titania; And providing a hydrogen-active metal precursor to the titania-coated alumina support and then encapsulating the hydrogen-active metal clusters through reduction of the titania.

In the step of coating the alumina support with titania, the Ti precursor may be TiCl ₂ , TiCl ₃ , TiCl ₄ , titanium oxysulfate, titanium diisopropoxidebis (acetylacetonate), titanium (IV) isopropoxide, titanium (IV) ethoxide, titanium (IV) butoxide, titanium (IV) propoxide, (IV) propoxide, titanium (IV) tert-butoxide, titanium (IV) fluoride, titanium (IV) barium titanate (IV), chlorotriisopropoxy titanium (IV), tetrabutyl titanate (IV), tetrabutyl titanate (IV) , Potassium hexafluorotitanate (VI) (potassium hexafluorot itanate (IV) or calcium titanate (IV). According to one embodiment of the present invention, the content of Ti precursor is such that the content of titania is 2 to 20% by weight, specifically about 4 to 12% by weight, based on the weight of the alumina support coated with titania, To about 6% to about 10% by weight.

Alumina sources may be present as alumina soluble salts, for example, sodium salts, chlorides, aluminum alcoholates, hydrated alumina (e.g. gamma alumina), pseudobohemite and colloidal alumina.

When using platinum as the active hydrogen precursors is by way of example, hydrogen active metal hydride (Hydrides), fluoride (Fluorides; for example _{PtF 6, PtF 4, [PtF} 5] 4 , etc.), chloride ( Chlorides; for example, _{PtCl 3, PtCl 4, Pt 6} Cl 12 and the like), bromide (bromides; PtBr _3, PtBr _4, etc.), iodides (iodides; for example, PtI _2, PtI _3, PtI _4, etc.), oxides (For example PtO, PtO ₂ , PtO), sulfides (e.g. PtS, PtS ₂ ), carbonyls (e.g., Pt (CO) ₄ ) and / or complexes ^;., for example _{[PtCl 2 (NH 3) 2} ], [PtCl 2 (NH 3) 2], K 2 [PtCl 6], K 2 [Pt (CN) 4], PtCl 4 5H 2 O, K [ _{PtCl 3 (NH 3)],} Na 2 [PtBr 6]. 6H 2 O, (NH 4) 2 [PtBr 6], K 2 [PtI 6], (NH 4) 2 [PtCl 6], K 2 [Pt _{(CN) 6], (NH} 4) 2 [PtCl 4], K 2 [Pt (NO 2) 4], K [PtCl 3 (C 2 H 4)]. H 2 O [Pt (NH 3) 4] _{(NO 3) 2, H 2} PtCl _6, but to use, and so on), this must be Information that is not. Also, for wet impregnation or ion exchange, the hydrogen active metal precursor may be applied in the form of an aqueous solution and / or an organic solution. Exemplary organic solvents include acetic acid, acetone, acetonitrile, benzene, 1-butanol, 2-butanol, 2-butanol, It is also possible to use 2-butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, 1,2-dichloroethane 1,2-dichloroethane, diethyl ether, diethylene glycol, diglyme (diethylene glycol dimethyl ether), 1,2-dimethoxy-ethane (DME), dimethyl ether, dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), dioxane, ethanol, ethyl acetate ), Ethylene glycol, glycerin, heptanes, hexamethylphosphoric acid, amide (HMPA), hexamethylphosphorostriamide (HMPT), hexane, methanol, methyl t-butyl ether (MTBE), methylene chloride, N N-methyl-2-pyrrolidinone (NMP), nitromethane, pentane, 1-propanol, 2-propanol, pyridine, tetrahydrofuran, THF), toluene, triethylamine, o-xylene, m-xylene, p-xylene, and the like. However, the present invention is not limited thereto.

According to one embodiment of the present invention, the content of the hydrogen-activated metal precursor is about 0.01 to 10% by weight, specifically about 0.1 to 2% by weight, based on the total weight of the dehydrogenation catalyst, , More specifically from about 0.5 to 1.5% by weight.

In the method for preparing a dehydrogenation catalyst according to the present invention, the step of coating the alumina support with titania may include the steps of adding an alumina support after dissolving the Ti precursor in deionized water, Deg.] C for 20 to 30 hours, filtering the stirred solution and then washing the filtered alumina support with deionized water and a KOH solution; And drying the washed alumina support and calcining the dried alumina support at 300 to 500 &lt; 0 &gt; C for 1 to 3 hours.

In the method for producing a dehydrogenation catalyst according to the present invention, the reduction of titania in the step of encapsulating the hydrogen active metal cluster may be performed by providing a hydrogen activated metal precursor to the coated alumina support and then heat treatment in a reducing atmosphere. According to one embodiment of the present invention, the reduction may be performed by heat treatment at 300 to 800 DEG C under a hydrogen atmosphere.

Another aspect of the present invention provides a dehydrogenation method for producing alkene by directly dehydrogenating an alkane using the dehydrogenation catalyst described above. When the above-described dehydrogenation catalyst is used in the dehydrogenation method, the CC hydrogenation reaction can be suppressed while maintaining the dehydrogenation reactivity in the alkane dehydrogenation reaction, thereby increasing the selectivity of the alkene. According to one embodiment of the present invention, the alkane as a reactant of the dehydrogenation reaction means a light alkane, preferably propane or butane. As described above, the dehydrogenation reaction according to the present invention can suppress the CC hydrocracking reaction. Therefore, when propane or butane is used as a reactant, the production of by-products such as methane or ethane can be minimized, Butene can be obtained with high yield. According to one embodiment of the present invention, the dehydrogenation reaction may be carried out at about 500 to 800 ° C, specifically about 550 to 700 ° C, more specifically about 600 to 650 ° C. Also, the molar ratio of hydrogen (H ₂ ) / alkane fed as reactant in the dehydrogenation reaction may be about 0.1 to 10, specifically 0.5 to 5, more specifically 0.5 to 1.

The catalyst used in the dehydrogenation process can be reused after impurities such as coke are accumulated in the catalyst and the impurities are removed through the catalyst regeneration process. The catalyst regeneration step may be carried out at a temperature of 200 to 700 ° C, specifically 400 to 600 ° C, more specifically 450 to 500 ° C. The regeneration gas used in the catalyst regeneration process may include all of the gases capable of removing the coke, and preferably includes O ₂ and CO ₂ , more preferably O ₂ . The concentration of regeneration gas may be from 0.1 to 100%, preferably from 0.5 to 20%, more preferably from 1 to 5%, in order to minimize the heat generated during catalyst regeneration.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the present invention is not limited thereto.

Example 1 A dehydrogenation catalyst (Pt-8 TiO ₂ / Al ₂ O ₃ )

Coating the alumina support with titania

3.438 g of Ti precursor was added to 300 ml of deionized water and stirred for about 1 hour until the solution became transparent. Titanium oxysulfate (TiS ₂ O ₁₀ H ₄ , FW = 276 g / mol) was used as the Ti precursor, and the amount of titanium oxysulfate was 3.438 g, which was the total weight of the titania-coated alumina support Based on this, the content is calculated so that the content of titania is 8 wt%. Then, when the solution became completely transparent, 10 g of gamma-alumina (STREM CHEMICALS, 13-2525) was added and stirred at 40 ° C for 24 hours. After 24 hours, the solution is filtered, then washed with 0.2 mol KOH to remove any residual sulfur and finally washed thoroughly (approximately 2 L) with 10 ^-3 M KOH solution. After the sample was sufficiently dried in the oven, it was ramped at 2 DEG C / min to 400 DEG C in an air atmosphere and held for 2 hours.

Encapsulating the hydrogen active metal cluster through reduction of titania

After applying a solution containing 0.2005 g of Pt precursor to 10 g of titania-coated alumina prepared in the previous step, a plastic spatula was used to remove the water from the solution. Rinse for minutes. Here, tetraammineplatinum nitrate (TAPt, Sigma-aldrich, 278726) was used as the Pt precursor. In addition, a non-metal plastic spatula was used because Pt could be reduced, and the amount of Pt precursor of 0.2005 g was calculated to be 1 wt% of Pt, based on the weight of the final catalyst produced later. The solution was prepared by adding 0.2005 g of TAPt to 7 g of water. Thereafter, the above samples were dried in an oven at 80 ° C. for about 3 hours, and then maintained in the air and hydrogen atmosphere at 400 ° C., respectively, and were reduced to produce a Pt-8TiO ₂ / Al ₂ O ₃ catalyst. As a reference, hydrogen and oxygen may react to generate heat, which may lead to sintering of Pt. Therefore, after air treatment or after hydrogen reduction, flushing should be performed with He for 30 minutes.

Example 2. Dehydrogenation catalyst (Pt-4 TiO ₂ / Al ₂ O ₃ )

In the same manner as in Example 1 except that the alumina support was coated with titania, a titania precursor calculated to have a titania content of 4 wt% based on the total weight of the alumina support coated with titania was added . Since the amount of Pt supported thereafter is the same as in Example 1, the weight ratio of Pt to TiO ₂ is different.

Example 3 Dehydrogenation Catalyst (Pt-10 TiO ₂ / Al ₂ O ₃ )

The titania precursor was coated on the alumina support in the same manner as in Example 1 except that the amount of the titania precursor was adjusted so that the content of the titania was 10 wt% based on the total weight of the alumina support coated with the titania . Since the amount of Pt supported thereafter is the same as in Example 1, the weight ratio of Pt to TiO ₂ is different.

Example 4. Dehydrogenation catalyst (Pt-20 TiO ₂ / Al ₂ O ₃ )

The titania precursor was coated on the alumina support in the same manner as in Example 1 except that the titania precursor was added so that the titania content was 20 wt% based on the total weight of the alumina support coated with titania . Since the amount of Pt supported thereafter is the same as in Example 1, the weight ratio of Pt to TiO ₂ is different.

Example 5. Direct dehydrogenation reaction of n-butane with supported catalyst

The activity of the supported catalyst prepared in Examples 1 to 4 was confirmed by the following method.

The dehydrogenation reaction of n-butane was carried out under conditions of 500 ° C and WHSV of 5.7 h ^-1 by supplying 20 kPa of n-butane, 20 kPa of H ₂ and 60 kPa of He. Before proceeding with the reaction, the catalyst used in the reaction was reduced in the reactor for 3 hours under the conditions described in Example 1. The dehydrogenation reaction of n-butane was measured over 40 hours.

The product components in the dehydrogenation reaction were analyzed using gas chromatography. The selectivities of the products (for example, butene, propene, isobutane, isopropane and the like) conversion ratios of the reactants (for example, butane and propane) were calculated by the following formulas (1) and (2).

[Equation 1]

&Quot; (2) &quot;

Reaction activity of catalyst depending on the content of titania

The results of the dehydrogenation reaction of n-butane using the catalysts prepared in Examples 1 to 4 and Comparative Example 1 are shown in Tables 2 and 2A and 2B.

division The Conversion Rate (%) Selectivity (%) Early boil Early boil Example 1 _{Pt-8TiO 2 / Al 2 O} 3 18.6 18.7 89.6 96.6 Example 2 _{Pt-4TiO 2 / Al 2 O} 3 20.6 19.7 82.2 95.2 Example 3 _{Pt-10TiO 2 / Al 2 O} 3 21.5 16.9 91.2 96.8 Example 4 _{Pt-20TiO 2 / Al 2 O} 3 20.0 11.7 93.8 97.5 Comparative Example 1 _{Pt-SnO 2 / Al 2 O} 3 21.1 20.2 84.6 89.8

* Initial: dehydrogenation reaction 10 minutes, boil: dehydrogenation 2000 minutes

According to Tables 2, 2A and 2B, the conversion of butane in Comparative Example 1 (Pt-SnO ₂ / Al ₂ O ₃ ) was as high as that of butane in Examples 1 to 4 (Pt-xTiO ₂ / Al ₂ O ₃ ) The degree of butene selectivity in Examples 1 to 4 was much higher than that in Comparative Example 1, As a result of the above reaction, the hydrocracking reaction and the isomerization reaction, which are the side reactions for producing methane and ethane, are suppressed while maintaining the dehydrogenation reactivity in the dehydrogenation reaction of the light alkane requiring high temperature in Examples 1 to 4 This indicates that the SMSI of Pt and TiO ₂ contributed greatly to the selectivity of the dehydrogenation reaction. The hydrocracking reaction and the isomerization reaction described above are shown in Figs. 2C and 2D. 2C and 2D, it can be seen that the selectivity of the hydrocracking reaction decreases with time in the case of Comparative Example 1, but the selectivity of the isomerization reaction is maintained at a high level over time Can be confirmed.

Example 6. Propane dehydrogenation reaction and catalyst regeneration test results

The dehydrogenation reaction of propane was carried out under the conditions of 580 캜 and WHSV of 7.2 h ^-1 by supplying n-butane of 20 kPa, H _{2 of} 10 kPa and He of 70 kPa. Before proceeding with the reaction, the catalyst used in the reaction was reduced in the reactor for 3 hours under the conditions described in Example 1. The dehydrogenation reaction of the propane was measured over 6 hours. After the dehydrogenation reaction over 6 hours, the catalyst regeneration experiment was carried out. Catalyst regeneration was carried out at 470 ° C for 3 hours using 1% O ₂ / He gas. Also, during the catalytic reaction catalyst regeneration-catalytic reduction step, He gas was caused to flow for 1 hour. The overall catalyst regeneration protocol is shown in Table 3.

The reaction (580 ° C) 6 hours He purge (580 ~ 470 ℃) 1 hours 1% O ₂ / He (470 ° C) 3 hours He purge (470 DEG C) 1 hours H ₂ (470-580 ° C) 1 hours

The evaluation results of the propane dehydrogenation and the regeneration results of the catalyst deactivated by carbon deposition after the regeneration procedure are shown in Tables 4, 3 and 4. FIG. 3 shows the tendency of the catalyst activity over time after each regeneration cycle, and Table 4 and FIG. 4 show the catalysts after 400 minutes elapsed in order to compare the activity of Example 1, The data on the activity of

division Conversion Rate (%) Selectivity (%) _{Pt-8TiO 2 / Al 2 O} 3 _{Pt-SnO 2 / Al 2 O} 3 _{Pt-8TiO 2 / Al 2 O} 3 _{Pt-SnO 2 / Al 2 O} 3 Cycle 1 25.4 21.4 96.0 96.9 Cycle 2 23.5 18.2 96.0 96.5 Cycle 3 22.4 15.2 95.9 96.0 Cycle 4 22.0 14.1 96.3 95.8 Cycle 5 21.6 11.0 96.5 94.9 Cycle 6 21.5 9.9 96.8 94.3

The experimental results shown in Table 4, FIG. 3 and FIG. 4 show that the Pt-8TiO ₂ / Al ₂ O ₃ catalyst is less inactivated in the single cycle test than the commercial Pt-SnO ₂ / Al ₂ O ₃ catalyst, The results also indicate that there is less deactivation. In addition, the selectivity of the Pt-SnO ₂ / Al ₂ O ₃ catalyst decreases gradually as the cycle progresses, while the Pt-8TiO ₂ / Al ₂ O ₃ catalyst is selected It shows that the degree gradually increases.

Claims (15)

Alumina support;
A titania layer coated on said alumina support; And
A hydrogen activated metal cluster encapsulated through reduction of the titania layer;
And a dehydrogenation catalyst comprising a chemical adsorption amount of hydrogen according to temperature satisfying the following relationship:
0.1 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <1
Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts denote the adsorption temperature (K). The method according to claim 1,
Wherein the relational expression is 0.3 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <0.8. The method according to claim 1,
Wherein the content of the titania layer is 2 to 20 wt% based on the weight of the alumina support coated with the titania layer. The method according to claim 1,
Wherein the content of the titania layer is 6 to 10 wt% based on the weight of the alumina support coated with the titania layer. The method according to claim 1,
Wherein the hydrogen-active metal is at least one metal selected from Group IB, Group VIIB and Group VIII metals in the periodic table. The method according to claim 1,
Wherein the diameter of the hydrogen-activated metal clusters is 0.5 to 50 nm. The method according to claim 1,
Wherein the content of the hydrogen-active metal is 0.5 to 1.5 wt% based on the total weight of the dehydrogenation catalyst. (a) dissolving a Ti precursor in deionized water and then adding an alumina support to coat the alumina support with titania; And
(b) providing a hydrogen-active metal precursor to the alumina support coated in step (a), and encapsulating the hydrogen-active metal clusters through reduction of titania, wherein the amount of chemical adsorption of hydrogen according to temperature is expressed by the following relationship : &Lt; / RTI &gt;
0.1 <[H / M ₃₂₃ ] / [H / M ₅₇₃ ] <1
Here, H / M represents a chemical adsorption amount (mol) of the hydrogen atom (H) per mol of the hydrogen active metal (M), and subscripts denote the adsorption temperature (K). The method of claim 8,
In the step (a), the Ti precursor is titanium oxysulfate, and the Ti precursor content is adjusted so that the content of titania is 2 to 20 wt% based on the weight of the alumina support coated with titania &Lt; / RTI &gt; The method of claim 8,
Wherein the content of the hydrogen-active metal precursor in the step (b) is adjusted so that the content of the hydrogen-active metal is 0.5 to 1.5% by weight based on the total weight of the dehydrogenation catalyst . The method of claim 8,
Wherein the reduction of titania in the step (b) is performed by heat-treating at 300 to 800 ° C under a hydrogen atmosphere. The method of claim 8,
The step (a)
(a1) dissolving the Ti precursor in deionized water and then adding an alumina support;
(a2) stirring the solution to which the alumina support is added in step (a1) at 30 to 50 DEG C for 20 to 30 hours;
(a3) filtering the stirred solution in step (a2) and washing the filtered alumina support with deionized water and a KOH solution; And
(a4) drying the alumina support washed in step (a3), and calcining the dried alumina support at 300 to 500 DEG C for 1 to 3 hours;
&Lt; / RTI &gt; by weight of the dehydrogenation catalyst. A process for dehydrogenating an alkene from an alkane in the presence of a catalyst prepared according to any one of claims 8 to 12. 14. The method of claim 13,
Wherein said alkane and alkene have 3 or 4 carbon atoms. 14. The method of claim 13,
Wherein the dehydrogenation process is carried out at 500 to 800 ° C. and the molar ratio of hydrogen / alkane fed to the dehydrogenation process is 0.1 to 10.

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