KR102478028B1 - Transition Metal-Noble Metal Complex Oxide Catalysts Prepared by One-Pot for Dehydrogenation and Use Thereof - Google Patents

Abstract

In an embodiment of the present invention, a first transition metal selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc, hydrogen selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table. An active metal and alumina, wherein the content of the first transition metal is 0.1% to 20% by weight based on the alumina, and the content of the hydrogen-activated metal is 0.01% to 2% by weight based on the alumina A composite oxide dehydrogenation catalyst, a method for preparing the same, and a use thereof are disclosed.

Description

Transition Metal-Noble Metal Complex Oxide Catalysts Prepared by One-Pot for Dehydrogenation and Use Thereof

The present invention relates to a one-pot synthesized transition metal-noble metal complex oxide dehydrogenation catalyst and its use.

Recently, as the production of shale gas containing a large amount of gases such as methane and ethane has rapidly increased, the economic feasibility of naphtha crackers has decreased and the economic feasibility of ethane crackers has greatly increased. As a result, the production of olefins such as propylene and butylene, which were produced as by-products of naphtha crackers, was greatly reduced. The demand for short-carbon olefins continues to increase and the supply of olefins tends to gradually decrease. Many studies are being conducted on propane and butane dehydrogenation processes that directly produce these olefins from propane and butane with short carbon lengths. there is.

The most representative propane and butane dehydrogenation catalysts include Pt-Sn/Al ₂ O ₃ (Oleflex process) and chromia-alumina (Catofin process) catalysts. It is already used in commercial processes because of its stability. However, in the case of the Pt-Sn/Al ₂ O ₃ catalyst, upon continuous catalyst regeneration, the concentration of Sn(0) continuously increases on the platinum surface, reducing the catalytic activity and causing a problem in platinum sintering. Therefore, in the commercial process, there is a disadvantage that oxychlorination must be included during catalyst regeneration. Even in the case of the chromia-alumina catalyst, the catalytic activity decreases due to migration of Cr ^{3+ and} sintering of alumina during continuous catalyst regeneration.

For the purpose of solving the deactivation phenomenon of the Pt-Sn/Al ₂ O ₃ catalyst, a metal (M) such as zinc, lanthanum, lithium, sodium, potassium, or rubidium is added to the catalyst to obtain Pt-Sn-M/Al A document prepared with a catalyst of the ₂ O ₃ type has been reported (KR 1,477,413 B1). This catalyst uses platinum (Pt) and tin (Sn) as essential components as in the prior art, and in particular, platinum functions as an active component directly involved in the dehydrogenation reaction as in the prior art, and the newly added metal (M) has a limited role in the dehydrogenation reaction because it has an auxiliary function to reduce the degree of inactivation of platinum. That is, the Pt-Sn-M/Al ₂ O ₃ catalyst is merely an extension of the conventional Pt-Sn/Al ₂ O ₃ catalyst. In addition, since the Pt-Sn-M/Al ₂ O ₃ type catalyst requires a process of impregnating metal components several times, the process is complicated and economically disadvantageous.

On the other hand, in order to overcome the limitations of conventional dehydrogenation catalysts for propane and butane, a literature using a catalyst in which Ga and a small amount (0.1 wt%) of platinum are supported on alumina has been reported (J. J. H. B. Sattler et al., Angew. Chem. , 126:9405, 2014 and US 2013/0178682 A1). In this document, gallium oxide was suggested as the main active site, and platinum was reported to help recombine hydrogen and increase reactivity. The catalyst showed an initial propane conversion rate of about 46%, but the propane conversion rate significantly decreased to about 30%, or 60% of the initial propane conversion rate, in 48 hours, and there was a limit to maintaining the 30% level for close to 15 days. According to the results of carbon monoxide chemisorption, it was confirmed that the dispersion of platinum significantly decreased from 20% to less than 5% after heat treatment. In carrying out the dehydrogenation reaction of olefins, it is extremely difficult to maintain a high degree of dispersion of platinum under catalyst regeneration conditions of 750 ° C and an air atmosphere. This is very important for maintaining early conversion rates.

In the specific example according to the present invention, the first transition metal is used as the active metal, the hydrogen activation metal and the second transition metal are used as the subsidiaries, and the precursors of each metal component and the alumina precursor are mixed together, and then the catalyst is prepared in one-pot. An object of the present invention is to provide a composite oxide dehydrogenation catalyst having an activity distinct from conventional catalysts by synthesis, a method for preparing the same, and a use thereof.

According to the first aspect of the present invention,

A first transition metal selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc;

At least one hydrogen-activated metal selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table, and

contains alumina,

The content of the first transition metal is 0.1% to 20% by weight based on the weight of the alumina, the content of the hydrogen-activated metal is 0.01% to 2% by weight based on the weight of the alumina, and the first transition metal A complex oxide dehydrogenation catalyst is provided in which silver is supported on the alumina, and the hydrogen-activated metal is surrounded by the alumina.

In an exemplary embodiment, the catalyst further comprises a second transition metal selected from the group consisting of cerium and zirconium, and the content of the second transition metal is 0.1% to 20% by weight based on the weight of the alumina, The second transition metal may be supported on the alumina.

In an exemplary embodiment, the hydrogen activation metal may be one or more selected from the group consisting of Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au.

According to a second aspect of the present invention,

preparing a precursor of a first transition metal selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc;

Preparing a precursor of one or more hydrogen-activated metals selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table;

preparing an alumina precursor;

mixing the first transition metal precursor, the hydrogen-activated metal precursor, and the alumina precursor in a one-pot; and

Synthesizing a catalyst using the mixture in the one-pot by a sol-gel method,

The content of the first transition metal is 0.1% to 20% by weight based on the weight of alumina in the final catalyst, and the content of the hydrogen-activated metal is 0.01% to 2% by weight based on the weight of alumina in the final catalyst. A method for preparing a dehydrogenation catalyst is provided.

In an exemplary embodiment, the method includes preparing a precursor of a second transition metal selected from the group consisting of cerium and zirconium; and

The method may further include mixing the precursor of the second transition metal in the one-pot, wherein the content of the second transition metal may be 0.1 wt% to 20 wt% based on the weight of alumina of the final catalyst.

In an exemplary embodiment, the method may include, after synthesizing the catalyst using the sol-gel method, at least one hydrogen-activated metal selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table. An impregnation step may be further included, and the content of the hydrogen-activated metal may be 0.01 wt% to 2 wt% based on the weight of alumina of the final catalyst.

In an exemplary embodiment, the method further comprises impregnating a second transition metal selected from the group consisting of cerium and zirconium, wherein the content of the second transition metal is 0.1% by weight based on the weight of alumina of the final catalyst. to 20% by weight.

In an exemplary embodiment, the method may further include drying the synthesized catalyst after synthesizing the catalyst using the sol-gel method, and then heat-treating the synthesized catalyst.

In an exemplary embodiment, the drying step may be performed at a temperature of 50 to 200 °C, and the heat treatment step may be performed at a temperature of 350 to 1000 °C.

In an exemplary embodiment, the hydrogen activation metal may be one or more selected from the group consisting of Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au.

According to the third aspect of the present invention,

providing at least one feedstock selected from the group consisting of methane, ethane, propane, butane, isobutane and cyclohexane; and

A method for producing olefins through dehydrogenation of the feedstock in the presence of the catalyst according to the first aspect or the catalyst prepared according to the second aspect is provided.

In an exemplary embodiment, the dehydrogenation reaction may be performed at a temperature of 300 to 800 °C.

The dehydrogenation catalyst according to an embodiment of the present invention has a first transition metal in alumina as an active component and a hydrogen-activating metal and a second transition metal as auxiliary components, so that even if the catalyst is frequently regenerated, the conversion rate of the dehydrogenation reaction, Selectivity and durability of the catalyst can be maintained for a long time.

The method for preparing a dehydrogenation catalyst according to an embodiment of the present invention uses a one-pot synthesis and a sol-gel method for a precursor of a metal component and a precursor of an alumina component. A catalyst having an activity can be provided.

1 shows a complex oxide catalyst prepared by using a one-pot synthesis and a sol-gel method of a first transition metal precursor, a second transition metal precursor, a hydrogen-activated metal precursor, and an alumina precursor according to an embodiment of the present invention. it is a drawing
2 is a graph showing propane conversion during 20 cycles of propane dehydrogenation and catalyst regeneration according to Example 1 of the present invention.
3 is a graph showing propylene selectivity during 20 cycles of propane dehydrogenation and catalyst regeneration according to Example 1 of the present invention.
4 is a graph showing isobutane conversion during 20 cycles of isobutane dehydrogenation and catalyst regeneration according to Example 2 of the present invention.
5 is a graph showing isobutylene selectivity during 20 cycles of isobutane dehydrogenation and catalyst regeneration according to Example 2 of the present invention.
6 is a graph showing the chemical adsorption amount of CO of the catalyst according to Example 3 of the present invention.
7 is a TEM image of a catalyst subjected to 20 cycles of dehydrogenation and regeneration of propane and isobutane according to Example 4 of the present invention.
8 is a graph showing the Pt L ₃ -edge X-ray Absorption Near-Edge Structue (XANES) spectrum of the catalyst before reaction according to Example 5 of the present invention.

The present invention can all be achieved by the following description. The following description should be understood as describing preferred embodiments of the present invention, but the present invention is not necessarily limited thereto. In addition, the accompanying drawings are for understanding, and the present invention is not limited thereto, and details of individual components can be properly understood by the specific purpose of the related description to be described later.

Terms used in this specification may be defined as follows.

"Dehydrogenation" means a reaction in which hydrogen is removed from a compound.

"Impregnation" refers to a method of preparing a catalyst by impregnating a solution in which a catalyst precursor is dissolved into a catalyst support such as alumina, silica, or titania having a large surface area, followed by drying and calcining. Among the impregnation methods, the incipient wetness impregnation method is the most widely used method, and refers to a method of preparing by supporting an impregnation solution corresponding to the pore volume of the catalyst support.

The “sol-gel method” refers to a method of preparing a catalyst having excellent dispersibility by dissolving a catalyst precursor in an organic solvent or water having a relatively high boiling point, mixing the support component therein, and then slowly hydrolyzing the catalyst precursor.

“One-pot synthesis” means that when a target compound is synthesized by a two or more reaction process, the next step is synthesized in one reaction vessel without otherwise purifying the product (intermediate product) of each step. Synthesis refers to a synthesis in which a target compound is obtained by continuously adding and reacting a reactant.

"Composite oxide" means an oxide in which two or more oxides are combined.

1 shows a one-pot synthesis and sol-gel method of a first transition metal precursor such as gallium, a second transition metal precursor such as cerium, a hydrogen-activated metal precursor such as platinum, and an alumina precursor according to an embodiment of the present invention. It is a drawing showing a complex oxide catalyst prepared using

Referring to FIG. 1, the composite oxide dehydrogenation catalyst according to one embodiment of the present invention is a one-pot using a sol-gel method to prepare a first transition metal precursor, a hydrogen-activated metal precursor, a second transition metal precursor, and an alumina precursor. It can be prepared by synthesizing.

The first transition metal may be selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc, but is not limited thereto. The content of the first transition metal may be 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the alumina of the final catalyst. If the content of the first transition metal is less than 0.1% by weight, the number of active sites may be too low, and if the content exceeds 20% by weight, the active sites of the transition metal may not be effectively used.

The hydrogen-activated metal is a group consisting of groups 8, 9, 10 and 11 on the periodic table, preferably a group consisting of Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au, more preferably may be one or more selected from the group consisting of Pt, Pd, and Ni, and most preferably may be a noble metal such as Pt. The content of the hydrogen-activating metal may be, for example, 0.01 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.1 to 0.5% by weight, based on the alumina of the final catalyst. If the content of the hydrogen-activating metal is less than 0.01% by weight, the interaction with the first transition metal may be insufficient, and if it exceeds 2% by weight, the olefin selectivity of the catalyst is reduced or the number of active sites is reduced because the first transition metal oxide is reduced can

The second transition metal may be selected from, for example, Zr and lanthanide metals, preferably Zr or Ce, and more preferably Ce, but is not limited thereto. The content of the second transition metal may be, for example, 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the alumina of the final catalyst. If the content of the second transition metal is less than 0.1% by weight, sintering of the hydrogen-activated metal cannot be suppressed, and if it exceeds 20% by weight, the second transition metal may not be effectively used.

Referring to FIG. 1, a hydrogen-activated metal, for example, a noble metal such as Pt, is surrounded by alumina supported with a first transition metal and a second transition metal. 6 and 7 show the CO chemisorption amount and TEM results of the sol-gel sample according to the embodiment of the present invention and the impregnation method sample according to the comparative example, respectively. On TEM, the Pt size of the samples obtained by the two synthesis methods was the same, but the amount of CO chemisorption was analyzed to be 30% lower in the sol-gel sample than in the impregnated sample. As such, it is proved from the CO chemisorption analysis result of FIG. 6 and the TEM analysis result of FIG. 7 that the hydrogen-activated metal (eg, Pt) is surrounded by alumina supported with the first transition metal and the second transition metal do. In this way, when the hydrogen-activated metal is surrounded by alumina, sintering caused by coalescence between hydrogen-activated metal clusters can be effectively suppressed. In addition, by adding the second transition metal to the catalyst, chemical interaction with the hydrogen-active metal can effectively suppress the sintering of the hydrogen-active metal. When synthesizing not only the hydrogen-activated metal but also the first transition metal and the second transition metal together with alumina by the sol-gel method in one-pot, the degree of dispersion of the first transition metal or the second transition metal in alumina is increased to activate these metals. Ingredients can work effectively.

In the sol-gel synthesis method, in the case of a composite oxide catalyst containing all of a first transition metal, a hydrogen-activated metal, and a second transition metal, alumina, a precursor of the first transition metal, hydrogen-activated metal, and second transition metal is mixed with a solvent ( For example, including the step of dissolving in water), including the step of hydrolyzing the alumina precursor by stirring after heating (eg, 358 K), and adding an acid (eg, HNO ₃ ) to alumina including the peptization process of A catalyst is prepared by evaporating all solvents from the synthesized solution, obtaining a sufficiently dried product, and then drying and heat-treating. In an exemplary embodiment, the drying may be performed at a temperature of 50 to 200 °C, and the heat treatment may be performed at a temperature of 350 to 1000 °C.

Preparation of Catalyst

In an embodiment of the present invention, the composite oxide dehydrogenation catalyst is a precursor of a first transition metal selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc when synthesizing an alumina precursor by a sol-gel method and on the periodic table A composite oxide dehydrogenation catalyst may be prepared by mixing one or more hydrogen-activated metal precursors selected from the group consisting of Groups 8, 9, 10, and 11 and synthesizing them in one-pot. In another embodiment, a composite oxide dehydrogenation catalyst may be prepared by further mixing a precursor of a second transition metal selected from the group consisting of cerium and zirconium and synthesizing the precursor in a one-pot manner. The mixing ratio of the precursors may be based on what has been described regarding the composition of the catalyst.

The alumina precursor may be selected from the group consisting of aluminum isopropoxide, aluminum nitrate nonahydrate, aluminum fluoride trihydrate, aluminum phosphate hydrate and aluminum chloride hexahydrate, but is not limited thereto.

As the precursor of the metal component, as long as it can be synthesized with the alumina precursor and sol-gel, salts, complexes, and the like of the metal known in the art can be used without limitation. Illustratively, when platinum is used as a precious metal, hydrides, fluorides (eg PtF ₆ , PtF ₄ , [PtF ₅ ] ₄ , etc.), chlorides (Chlorides; eg PtCl ₃ , PtCl ₄ , Pt ₆ Cl ₁₂ etc.), bromides (PtBr ₃ , PtBr ₄ etc.), iodides (eg PtI ₂ , PtI ₃ , PtI ₄ etc.), oxides (eg PtO, PtO ₂ , PtO, etc.), Sulfides (eg PtS, PtS ₂ etc.), Carbonyls (eg Pt(CO) ₄ ) and/or Complexes (eg [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 , etc.) may be used, but is not necessarily limited thereto.

The sol-gel process uses an organic or inorganic metal compound as a solution and proceeds with hydrolysis and condensation polymerization of the compound in the solution to solidify the sol into a gel, and then solidify the sol into a gel. It is a method of producing an oxide by heating. This sol-gel method can be largely divided into two types according to the gelation mode. First, the colloidal method is a method in which a sol, which is a raw material solution, is formed by dispersing colloidal particles in a solution, and then gelated by destabilization of the sol state. In the second method, a metal organic compound such as an alkoxide is used as a starting material to form a sol, which is then converted into a gel through hydrolysis and polymer concentration. In the present invention, such a sol-gel method can be applied to a method commonly used from the point of view of a person skilled in the art.

In the sol-gel synthesis method, in the case of a composite oxide catalyst containing all of a first transition metal, a hydrogen-activated metal, and a second transition metal, alumina, a precursor of the first transition metal, a noble metal, and a second transition metal are mixed with a solvent (eg, For example, water), including the step of hydrolyzing the alumina precursor by stirring after raising the temperature (eg, 358 K), and peptizing alumina according to the addition of an acid (eg, HNO ₃ ) (peptization) process may be included. A catalyst can be prepared by evaporating all solvents from the synthesized solution, obtaining a sufficiently dried product, and then drying and heat-treating.

In an embodiment of the present invention, after the step of synthesizing the catalyst using the sol-gel method, drying and heat treatment of the synthesized catalyst may be further included.

Since the purpose of drying is to remove the remaining moisture after the gel is formed, the drying temperature and drying time may be limited according to general moisture drying conditions. For example, the drying temperature is 50 ~ 200 ℃, preferably 70 ~ 120 ° C., drying time can be set to 3 to 24 hours, preferably 6 to 12 hours.

The heat treatment is performed for the purpose of forming metal-alumina, and is preferably performed in a temperature range of 350 to 1000 ° C, preferably 500 to 800 ° C, for 1 to 12 hours, preferably for 3 to 6 hours. . When the heat treatment temperature is less than 350 ° C or the heat treatment time is less than 1 hour, it is not preferable because the formation of metal-alumina is not sufficient, and when the heat treatment temperature exceeds 1000 ° C or the heat treatment time exceeds 12 hours, metal-alumina This is undesirable because there is a possibility that the garment may be denatured.

Usage

According to another embodiment of the present invention, the complex oxide catalyst can be applied to various dehydrogenation processes and exhibits improved activity. Dehydrogenation methods include, for example, a method for converting methane to olefin, a method for converting propane to propylene, a method for converting butane to butene or butadiene, and a method for converting cyclohexane to benzene, but are not limited thereto no.

When the reactant (eg, methane, ethane, propane, butane, isobutane, cyclohexane, or a mixture thereof) is supplied to the reactor, the amount of the reactant injected can be adjusted using a mass flow controller, and the amount of reactant injected is the total It is preferable to set the catalyst amount so that the weight hourly space velocity (WHSV) is 0.5 to 100 hr ^-1 , preferably 1 to 50 hr ^-1 , more preferably 2 to 25 hr ^-1 based on the reactants Do. When the space velocity is less than 0.5 hr ^-1 , the production of olefins is too small, which is not preferable, and when the space velocity exceeds 100 hr ^-1 , coking deposition due to reaction by ^- products of the catalyst rapidly occurs.

The reaction temperature for proceeding the direct dehydrogenation reaction of the reactants is preferably 300 to 800 ° C, more preferably 500 to 700 ° C, 620 ° C in the case of propane dehydrogenation, and 550 ° C in the case of butane dehydrogenation. It is best to keep When the reaction temperature is less than 300 ° C., the reaction of the reactants is not sufficiently activated, which is not preferable, and when the reaction temperature exceeds 800 ° C., the decomposition reaction of the reactant, for example, butane, mainly occurs, which is not preferable.

Hereinafter, preferred embodiments are presented to aid understanding of the present invention, but the following examples are provided to more easily understand the present invention, but the present invention is not limited thereto.

Preparation Example 1

Preparation of a first transition metal-noble metal-alumina composite catalyst using a one-pot sol-gel method

In one embodiment, the composite catalyst may be prepared by one-pot synthesis and sol-gel method of the first transition metal precursor, noble metal precursor, and alumina precursor.

In an exemplary embodiment, a Pt-Ga/Al ₂ O ₃ composite catalyst may be synthesized. Tetraamineplatinum nitrate (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ), gallium nitrate (Ga(NO ₃ ) ₃ ), and aluminum isopropoxide ( C ₉ H ₂₁ AlO ₃ ) were used as precursors for platinum, gallium, and alumina, respectively. Tetraamine platinum nitrate and gallium nitrate were mixed with about 0.04 g of tetraamine platinum nitrate and about 2.27 g of gallium nitrate so that the platinum and gallium contents were about 0.1 wt% and about 3 wt%, respectively, based on the alumina of the final catalyst. After putting the rate in about 700 ml of distilled water to make an aqueous solution, the mixture was stirred at about 358 K. About 80.1 g of aluminum isopropoxide was added to the aqueous solution in which the precursors of platinum and gallium were completely dissolved, and the mixture was further stirred at about 358 K for about 30 minutes. About 8.1 g of nitric acid (HNO ₃ , about 61% solution) was added to the aluminum isopropoxide hydrolyzed solution for peptization, and the synthesized solution was continuously stirred for about 12 hours until all distilled water evaporated. did After taking the sufficiently dried product, it was calcined at about 1023 K for about 2 hours in dry air, and the prepared catalyst was expressed as “Pt-Ga/Al ₂ O ₃ (solgel)”.

Preparation Example 2

Preparation of a first transition metal-noble metal-second transition metal-alumina composite catalyst using a one-pot sol-gel method

In one embodiment, the second transition metal may be selected from the group consisting of cerium and zirconium. In an exemplary embodiment, cerium nitrate (Ce(NO ₃ ) ₃ ) is used as a precursor of cerium, and platinum, gallium, and cerium are respectively about 0.1 wt%, about 0.1 wt%, based on alumina of the final catalyst. About 0.04 g of tetraamineplatinum nitrate, about 2.27 g of gallium nitrate, and about 0.62 g of cerium nitrate were mixed to about 700 After preparing a catalyst in the same manner as in Preparation Example 1 by making an aqueous solution by adding ml of distilled water, the heat-treated catalyst was referred to as "Pt-Ga-Ce/Al ₂ O ₃ (solgel)". According to the production example of the present invention, since all catalyst components are mixed together and synthesized in one-pot, only one heat drying/heat treatment process is required.

Preparation Example 3

Preparation of 1wt% Pt-Ga-Ce/Al ₂ O ₃ composite catalyst using one-pot sol-gel method

In one embodiment, the complex catalyst may be prepared by one-pot synthesis and sol-gel method of the first transition metal precursor, noble metal precursor, second transition metal precursor, and alumina precursor. As an exemplary embodiment, a 1 wt% Pt-Ga-Ce/Al ₂ O ₃ composite catalyst may be synthesized. Gallium nitrate (Ga(NO ₃ ) ₃ ), tetraamine platinum nitrate, cerium nitrate, and aluminum isopropoxide (C ₉ H ₂₁ AlO ₃ ) were prepared by combining gallium, platinum and cerium, respectively. and a precursor of alumina. Tetraamine platinum nitrate, gallium nitrate, and cerium nitrate were mixed with about 0.4 g of tetraamine such that the contents of platinum, gallium, and cerium were about 1 wt%, about 3 wt%, and about 1 wt%, respectively, based on alumina in the final catalyst. Amine platinum nitrate, about 2.27 g of gallium nitrate, and about 0.62 g of cerium nitrate were put into about 700 ml of distilled water to make an aqueous solution, and a catalyst was prepared in the same manner as in Preparation Example 1, and the heat-treated catalyst was "1 wt%". Pt-Ga-Ce/Al ₂ O ₃ (solgel)".

Comparative Preparation Example 1

Preparation of a first transition metal-alumina composite catalyst using a one-pot sol-gel method

In one comparative preparation example, the composite catalyst can be prepared by one-pot synthesis and sol-gel method of the first transition metal precursor and the alumina precursor. As an exemplary comparative preparation example, a Ga/Al ₂ O ₃ composite catalyst may be synthesized. Gallium nitrate (Ga(NO ₃ ) ₃ ) and aluminum isopropoxide (C ₉ H ₂₁ AlO ₃ ) were used as precursors of gallium and alumina, respectively. About 2.27 g of gallium nitrate was added to about 700 ml of distilled water so that the content of gallium was about 3 wt% based on the alumina of the final catalyst to make an aqueous solution, and then the mixture was stirred at about 358 K. About 80.1 g of aluminum isopropoxide was added to the aqueous solution in which the gallium precursor was completely dissolved, and further stirred at about 358 K for about 30 minutes. About 8.1 g of nitric acid (HNO ₃ , about 61% solution) was added to the aluminum isopropoxide hydrolyzed solution for peptization, and the synthesized solution was continuously stirred for about 12 hours until all distilled water evaporated. did After taking the sufficiently dried product, it was calcined at about 1023 K for about 2 hours in dry air, and the prepared catalyst was expressed as “Ga/Al ₂ O ₃ (solgel)”.

Comparative Preparation Example 2

Synthesis of Pt-Ga/Al ₂ O ₃ composite catalyst using incipient wetness impregnation

Tetraamineplatinum nitrate (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ) and gallium nitrate (Ga(NO ₃ ) ₃ ) were used as precursors of platinum and gallium, respectively. In commercial alumina (gamma-alumina, STREM CHEMICALS), tetraamine platinum nitrate and gallium nitrate were prepared by an initial wet impregnation method ( Incipient wetness impregnation) was impregnated in commercial alumina. The impregnated alumina was dried at about 373 K for about 24 hours and then calcined at about 1023 K for about 2 hours in dry air. The prepared catalyst was expressed as “Pt-Ga/Al ₂ O ₃ (imp)”.

Comparative Preparation Example 3

Synthesis of Pt-Ga-Ce/Al ₂ O ₃ composite catalyst using incipient wetness impregnation

Additionally tetraamineplatinum nitrate, gallium nitrate and cerium such that platinum, gallium and cerium are about 0.1 wt%, about 3 wt% and about 1 wt%, respectively, based on alumina in the final catalyst. After carrying nitrate (cerium nitrate) on commercial alumina by the initial wet impregnation method using the method of Comparative Preparation Example 2, the catalyst heat-treated under the same conditions was called "Pt-Ga-Ce/Al ₂ O ₃ (imp)". showed up As such, according to Comparative Preparation Example 3, at least three heat drying/heat treatment processes are required.

Example 1

Measurement of propane dehydrogenation reactivity

Synthesized Pt-Ga/Al ₂ O ₃ (imp), Pt-Ga-Ce/Al ₂ O ₃ (imp), Pt-Ga/Al ₂ O ₃ (solgel), Pt-Ga-Ce/Al ₂ O ₃ (solgel), Ga/Al ₂ O ₃ (solgel), and 1 wt% Pt-Ga-Ce/Al ₂ O ₃ (solgel) sample in which the content of platinum was increased to 1 wt%. Propane dehydrogenation reaction /catalyst regeneration cycle experiments were performed.

Prior to the propane dehydrogenation reaction, each sample was molded to about 75 to about 100 mesh to minimize the effect on heat and mass transfer, and was used as a final catalyst for the reaction. The reaction was carried out in a fixed-bed continuous flow reactor with about 0.6 g of catalyst, and all samples were in-situ at about 893 K and a He flow rate of about 200 sccm prior to the reaction. processed. The dehydrogenation reaction of propane was carried out under operating conditions (WHSV = about 5.4 h ⁻¹ , 893 K, P _He = about 80 kPa, P _propane = about 20 kPa). After the reaction proceeded for about 1 hour, the next reaction proceeded through catalyst regeneration. Specifically, the reaction/catalyst regeneration cycle experiment was performed through the following procedure.

(i) conducting a propane dehydrogenation reaction at about 893 K for about 1 hour;

(ii) flowing helium at about 893 K for about 30 minutes;

(iii) regenerating the catalyst with dry air at about 893 K for about 30 minutes;

(iv) flowing helium at about 893 K for about 30 minutes; and

(v) carrying out a second propane dehydrogenation reaction at about 893 K.

A total of 20 cycles of the catalytic reaction/regeneration cycle experiment were performed, and propane conversion and propylene selectivity 10 minutes after the reactants started to be injected were analyzed using on-line GC. Propane dehydrogenation conversion and propylene selectivity of the catalyst are shown in FIGS. 2 and 3 . As a result of the reaction, it was confirmed that the activity and regeneration of the Pt-Ga-Ce/Al ₂ O ₃ (solgel) catalyst synthesized by the sol-gel method with the addition of cerium were the best. In addition, the propane dehydrogenation activity of 1wt% Pt-Ga-Ce/Al ₂ O ₃ (solgel) in which the platinum content was increased to about 1% by weight was also measured, and the results are shown in FIGS. 2 and 3 . According to one embodiment of the present invention, since Ga is the main active site, the content of Pt is preferably about 0.1% by weight based on alumina. When the content of platinum is increased to 1% by weight, as shown in FIGS. 2 and 3, the catalyst performance is rather reduced. As such, the catalyst according to the present invention may be characterized in the appropriate content of constituents. The fact that the Pt 1% catalyst is less active than the Pt 0.1% catalyst in the catalyst according to the embodiment of the present invention indicates that the noble metal, for example platinum, is not the main active material.

Example 2

Measurement of isobutane dehydrogenation reactivity

Synthesized four catalysts Pt-Ga/Al ₂ O ₃ (imp), Pt-Ga-Ce/Al ₂ O ₃ (imp), Pt-Ga/Al ₂ O ₃ (solgel), Pt-Ga-Ce/Al For ₂ O ₃ (solgel), an isobutane dehydrogenation reaction/catalyst regeneration cycle experiment was performed.

Prior to the isobutane dehydrogenation reaction, each sample was molded to about 75 to about 100 mesh to minimize the effect on heat and mass transfer and used as a final catalyst for the reaction. The reaction was carried out in a fixed-bed continuous flow reactor with about 0.6 g of the catalyst, and all samples were in-situ at about 823 K and a He flow rate of about 200 sccm prior to the reaction. processed. The dehydrogenation reaction of isobutane was performed under operating conditions (WHSV = about 7.1 h ^-1 , about 823 K, P _He = about 80 kPa, P _isobutane = about 20 kPa). After the reaction proceeded for about 1 hour, the next reaction proceeded through catalyst regeneration. Specifically, the reaction/catalyst regeneration cycle experiment was performed through the following procedure.

(i) conducting an isobutane dehydrogenation reaction at about 823 K for about 1 hour;

(ii) flowing helium at about 823 K for about 30 minutes;

(iii) regenerating the catalyst with dry air at about 823 K for about 30 minutes;

(iv) flowing helium at about 823 K for about 30 minutes; and

(v) carrying out a second isobutane dehydrogenation reaction at about 823 K.

A total of 20 cycles were performed in the catalytic reaction/regeneration cycle experiment, and the isobutane conversion and isobutylene selectivity about 10 minutes after the reactants started to be injected were analyzed using on-line GC. The isobutane dehydrogenation conversion rate and isobutylene selectivity of the catalyst are shown in FIGS. 4 and 5 . As a result of the reaction, it was confirmed that the activity and regeneration of the Pt-Ga-Ce/Al ₂ O ₃ (solgel) catalyst synthesized by the sol-gel method with the addition of cerium were the best.

Example 3

Carbon monoxide chemisorption (CO chemisorption) analysis

Pt-Ga/Al ₂ O ₃ (imp), Pt-Ga/Al ₂ O ₃ (solgel) and Pt-Ga-Ce/Al ₂ O ₃ (solgel) catalysts before/after propane and isobutane dehydrogenation reaction In order to analyze the dispersion of platinum exposed to the surface, the amount of chemical adsorption of CO at about 323 K was measured and analyzed using ASAP2020 (Micromeritics) equipment (volumetric vacuum method), and the results are shown in FIG. 6 . Prior to adsorption analysis, all samples were reduced for about 3 hours while flowing H ₂ (about 100 sccm) at about 723 K, and vacuum treated at the same temperature for about 3 hours. Then, the amount of chemical adsorption was measured at about 323 K, which is the carbon monoxide adsorption temperature. In order to increase the accuracy of the analysis, the same analysis was performed 5 times per sample and the average value was obtained. As a result of carbon monoxide chemical adsorption, in the case of Pt-Ga/Al ₂ O ₃ (imp) synthesized by the conventional incipient wetness impregnation method, the dispersion degree of platinum after the propane dehydrogenation reaction/catalyst regeneration cycle test was the catalyst before the reaction. It was found that there was a significant decrease compared to On the other hand, in the case of Pt-Ga/Al ₂ O ₃ (solgel) synthesized by the sol-gel method by mixing in a one-pot, the dispersion of platinum was maintained high after the reaction, and Pt-Ga-Ce/Al with additional cerium added. In the case of ₂ O ₃ (solgel), the dispersion of platinum was maintained higher after the reaction. Even after the isobutane dehydrogenation reaction, the overall dispersion was not significantly reduced compared to the propane dehydrogenation reaction, but the relative dispersion between samples was similar to that of the propane dehydrogenation reaction.

Example 4

Transmission Electron Microscope (TEM) Analysis

TEM images were analyzed after 20 cycles of propane and isobutane dehydrogenation and regeneration for Pt-Ga/Al ₂ O ₃ (imp) and Pt-Ga-Ce/Al ₂ O ₃ (solgel) catalysts. is shown in Figure 7. As shown in the figure, in the case of the Pt-Ga-Ce/Al ₂ O ₃ (solgel) sample, the size of the platinum cluster after the reaction is smaller and dispersed than that of the Pt-Ga/Al ₂ O ₃ (imp) was found to be

Example 5

Pt L ₃ -edge XANES (X-ray Absorption Near-Edge Structure) Analysis

The three synthesized catalysts Pt-Ga/Al ₂ O ₃ (imp), Pt-Ga/Al ₂ O ₃ (solgel), Pt-Ga-Ce/Al ₂ O ₃ (solgel) and platinum foil (Pt foil) as a control For Pt L ₃ -edge XANES analysis was performed, and the results are shown in FIG. 8 . As shown in FIG. 8, the intensity of the white line at the Pt L ₃ -edge absorption edge is Pt-Ga/Al ₂ O ₃ (imp), Pt-Ga/Al ₂ O ₃ (solgel), and Pt-Ga -Ce/Al ₂ O ₃ (solgel) was confirmed to increase in order. Since the white line intensity of Pt-Ga/Al ₂ O ₃ (solgel) having the same chemical composition as Pt-Ga/Al ₂ O ₃ (imp) is greater, it can be seen that platinum interacts more strongly with alumina, This can be interpreted as an increase in the interface between platinum and alumina as platinum is surrounded by alumina. In addition, since the white line intensity of Pt-Ga-Ce/Al ₂ O ₃ (solgel) is the largest, it can be interpreted that platinum is more strongly stabilized.

Simple modifications or changes of the present invention can be easily used by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (12)

delete delete preparing a precursor of a first transition metal selected from the group consisting of gallium, vanadium, chromium, manganese, molybdenum, and zinc;
Preparing a precursor of one or more hydrogen-activated metals selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table;
preparing an alumina precursor;
mixing the first transition metal precursor, the hydrogen-activated metal precursor, and the alumina precursor in a one-pot; and
and synthesizing a catalyst using the mixture in the one-pot by a sol-gel method, wherein the content of the first transition metal is 0.1% to 20% by weight based on the weight of alumina of the final catalyst, and the hydrogen activation Method for producing a composite oxide dehydrogenation catalyst wherein the content of the metal is 0.01% to 2% by weight based on the weight of alumina in the final catalyst. The method of claim 3,
preparing a precursor of a second transition metal selected from the group consisting of cerium and zirconium; and
Further comprising mixing the precursor of the second transition metal in the one-pot, wherein the content of the second transition metal is 0.1% to 20% by weight based on the weight of alumina of the final catalyst. manufacturing method. According to claim 3 or 4,
Following the step of synthesizing the catalyst using the sol-gel method, further comprising impregnating one or more hydrogen-activated metals selected from the group consisting of groups 8, 9, 10, and 11 on the periodic table, wherein the hydrogen The content of the activated metal is 0.01% to 2% by weight based on the weight of alumina in the final catalyst. Method for producing a composite oxide dehydrogenation catalyst. According to claim 3 or 4,
Further comprising impregnating a second transition metal selected from the group consisting of cerium and zirconium, wherein the content of the second transition metal is 0.1% to 20% by weight based on the weight of alumina of the final catalyst. Composite oxide dehydrogenation catalyst Manufacturing method of. According to claim 3 or 4,
Method for producing a composite oxide dehydrogenation catalyst further comprising drying the synthesized catalyst after synthesizing the catalyst using the sol-gel method and then heat-treating. The method of claim 7,
The drying step is performed at a temperature of 50 ~ 200 ℃, the heat treatment step is a method for producing a composite oxide dehydrogenation catalyst carried out at a temperature of 350 ~ 1000 ℃. providing at least one feedstock selected from the group consisting of methane, ethane, propane, butane, isobutane and cyclohexane; and
A method for producing olefins comprising the step of subjecting the feedstock to a dehydrogenation reaction in the presence of a catalyst prepared by claim 3 or 4. The method of claim 9,
The dehydrogenation reaction is a method for producing olefins carried out at a temperature of 300 ~ 800 ℃. delete The method of claim 3,
The hydrogen-activated metal is a method for producing a composite oxide dehydrogenation catalyst selected from at least one selected from the group consisting of Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au.

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