KR102310394B1 - Alkaline earth metal catalyst supported on perovskite carrier and method for oxidative coupling reaction of methane using the same - Google Patents

Abstract

The present disclosure discloses an alkaline earth metal catalyst supported on a perovskite support and a method for oxidative dimerization of methane using the same. The perovskite structure has _{a formula of ABO 3} , wherein A is any one selected from Ca, Sr, Ba and Mg, and B is Ti. The catalyst has the effect of providing a _{high C 2+} hydrocarbon yield by greatly improving the _{conversion rate of methane and the selectivity of the C 2+} hydrocarbon compound even when the oxidation dimerization reaction of methane is carried out at a temperature of 700 ° C. or less.

Description

Alkaline earth metal catalyst supported on perovskite support and oxidation dimerization reaction method of methane using same

The present disclosure discloses an alkaline earth metal catalyst supported on a perovskite support and a method for oxidative dimerization of methane using the same.

Methane is a major component of natural gas or shale gas, and is very abundant in nature. Its uses are also very diverse, so it can be used directly as a fuel, but by connecting carbon chains using direct/indirect conversion technology, it can be converted into hydrocarbons with higher added value.

Techniques for converting methane into high value-added hydrocarbons by linking carbon chains are well known. If we classify methane conversion technology into two, it can be divided into indirect conversion technology and direct conversion technology. The indirect conversion technology is a technology to obtain a carbon compound by producing syngas using the reforming reaction of methane and further processing the syngas produced here. Although this method has been commercialized, a large amount of energy is consumed in the process and the initial investment cost is high. In order to solve this problem, a technology for directly converting methane is being studied. Although the direct conversion technology has the advantage of converting methane to carbon compounds using a single reaction, it still has limitations in terms of economic feasibility and selectivity. In order to solve this problem, many catalyst technologies and process technologies are being studied.

One of the direct conversion techniques for methane is to use the oxidation dimerization reaction of methane. This is a method of generating _{C 2+} hydrocarbons by converting methane into methyl radicals under high temperature conditions of 700 ° C. or higher and then pairing them. This reaction is shown in <Scheme 1> below.

<Scheme 1>

2CH ₄ + O ₂ → C ₂ H ₄ + 2H ₂ O

If the oxidation dimerization reaction of methane is used, methane can be converted to ethylene using a single process as shown in <Scheme 1>. However, when ethylene or ethane produced under high temperature conditions is completely oxidized, it is converted to carbon dioxide, which inevitably results in lowering the selectivity of _{C 2 hydrocarbons.} Therefore, while lowering the oxidative dimerization reaction temperature conditions of methane, increasing the conversion rate of methane and _{the selectivity of C 2} hydrocarbons will provide a catalyst having a complex economic feasibility.

KR 10-2015-0087557 A

In one aspect, an object of the present disclosure is to provide a catalyst in which an alkaline earth metal oxide is supported on a support having a perovskite structure.

In another aspect, an object of the present disclosure is to provide a method for oxidative dimerization of methane using the catalyst.

In one aspect, the present disclosure provides a support of a perovskite structure; And it provides a catalyst for the oxidation dimerization reaction of methane comprising an alkaline earth metal oxide supported on the support.

In an exemplary embodiment, the perovskite structure may have the following formula.

ABO ₃

In the above formula, A and B are elements that are not identical to each other, A is any one selected from Ca, Sr, Ba, and Mg, and B is Ti.

In an exemplary embodiment, the alkaline earth metal may be at least one selected from the group consisting of Ca, Sr, Ba, and Mg.

In an exemplary embodiment, in the catalyst, at least one alkaline earth metal oxide selected from the group consisting of calcium oxide, strontium oxide and barium oxide is a perovskite of any one of calcium titanate, strontium titanate, and barium titanate It may be supported on a support of the structure.

In an exemplary embodiment, the catalyst may include an alkaline earth metal oxide and a support in a weight ratio of 1:5 to 1:15.

In an exemplary embodiment, the catalyst may be one in which an aqueous alkaline earth metal precursor solution is mixed with an aqueous solution of a support having a perovskite structure to support an alkaline earth metal in the form of an oxide on a support having a perovskite structure.

In an exemplary embodiment, the catalyst may be to produce a _{C 2+ hydrocarbon compound from methane.}

In an exemplary embodiment, the C ₂₊ hydrocarbon compound may include one or more selected from the group consisting of ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ) and acetylene (C ₂ H _{2 ).} have.

In another aspect, the present disclosure provides a method for oxidative dimerization of methane, which includes preparing a hydrocarbon compound containing two or more carbon atoms from methane by adding the catalyst for oxidative dimerization of methane to methane.

In an exemplary embodiment, the method includes: introducing a mixed gas including methane, oxygen and an inert gas into the reactor; and adding a catalyst for oxidative dimerization of methane in the reactor to perform oxidative dimerization of methane.

In an exemplary embodiment, the oxidation dimerization reaction of methane may be carried out at 550 to 750 °C.

In one aspect, the technology disclosed in the present disclosure is effective in providing a catalyst in which an alkaline earth metal oxide is supported on a support having a perovskite structure.

The catalyst disclosed in the present disclosure provides the effect of producing _{C 2+} hydrocarbons in high yield by increasing the conversion rate of methane and the selectivity _{of C 2+} hydrocarbons while lowering the oxidation dimerization reaction temperature condition of methane.

In another aspect, the technology disclosed in the present disclosure has the effect of providing a method for oxidative dimerization of methane using the catalyst.

1 is a schematic diagram of the configuration of a continuous methane oxidation dimerization reactor used for the production of _{C 2+} hydrocarbon compounds according to an embodiment.

Hereinafter, the present disclosure will be described in detail.

In one aspect, the present disclosure provides a support of a perovskite structure; And it provides a catalyst for the oxidation dimerization reaction of methane comprising an alkaline earth metal oxide supported on the support.

As used herein, "C ₂ hydrocarbon compound" refers to a hydrocarbon compound having two carbon atoms.

As used herein, "C ₂₊ hydrocarbon compound" means a hydrocarbon compound having two or more carbon atoms.

In an exemplary embodiment, the perovskite structure may have the following formula.

ABO ₃

In the above formula, A and B are elements that are not identical to each other, A is any one selected from Ca, Sr, Ba, and Mg, and B is Ti.

In an exemplary embodiment, the alkaline earth metal may be at least one selected from the group consisting of Ca, Sr, Ba, and Mg.

In an exemplary embodiment, the alkaline earth metal may be an element that is not the same as A of the perovskite structure.

In an exemplary embodiment, the alkaline earth metal may be supported in the form of an oxide on a support having a perovskide structure by mixing an aqueous alkaline earth metal precursor solution with an aqueous support solution having a perovskide structure.

In an exemplary embodiment, in the catalyst, at least one alkaline earth metal oxide selected from the group consisting of calcium oxide, strontium oxide and barium oxide is a perovskite of any one of calcium titanate, strontium titanate, and barium titanate It may be supported on a support of the structure.

In an exemplary embodiment, the catalyst may be one in which barium oxide is supported on a support of calcium titanate or strontium titanate.

In an exemplary embodiment, the catalyst may be one in which at least one alkaline earth metal oxide selected from the group consisting of calcium oxide and strontium oxide is supported on barium titanate.

In an exemplary embodiment, the catalyst includes an alkaline earth metal oxide and a support in a weight ratio of 1: 5 to 1: 15, a weight ratio of 1: 5 to 1: 10, a weight ratio of 1: 7 to 1: 13, or 1: 10 to It may be preferable to include it in a weight ratio of 1:15.

In an exemplary embodiment, the catalyst may be to produce a _{C 2+ hydrocarbon compound from methane.}

In an exemplary embodiment, the C ₂₊ hydrocarbon compound may include one or more selected from the group consisting of ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ) and acetylene (C ₂ H _{2 ).} have.

In an exemplary embodiment, the catalyst may exhibit excellent activity even in a low-temperature methane oxidation dimerization reaction. More specifically, it is possible to prepare a hydrocarbon compound containing two or more carbon atoms in a high yield under a temperature condition of 700 ° C. or less, for example, 600 to 700 ° C.

In another aspect, the present disclosure provides a method for preparing a catalyst for the oxidation dimerization reaction of methane, comprising: preparing a solution including a support having a perovskite structure; mixing and stirring the solution and the alkaline earth metal precursor solution; and drying and calcining the mixed solution. It provides a method for preparing a catalyst for oxidative dimerization of methane.

In an exemplary embodiment, the precursor may be at least one selected from the group consisting of a salt compound, an acetate compound, a halogen compound, a nitrate compound, a hydroxide compound, a carbonyl compound, a sulfate compound, and a fatty acid salt compound.

In an exemplary embodiment, the drying may be carried out in an air atmosphere of 200 to 250 ℃.

In an exemplary embodiment, the sintering may be carried out in an air atmosphere of 500 to 1,000 °C.

The catalyst for oxidative dimerization of methane disclosed in the present specification serves to mediate the coupling reaction after converting methane into methyl radicals by using it after converting oxygen into oxygen radicals by attracting oxygen. In this process, it helps the movement of oxygen and electrons and activates methane. Accordingly, it is possible to promote the oxidation dimerization reaction of methane. In addition, the catalyst can prepare a C ₂₊ hydrocarbon compound in a high yield through the oxidation dimerization reaction of methane.

The _{step of preparing the C 2+} hydrocarbon compound may be to proceed with the oxidation dimerization reaction of methane by raising the reactor to a predetermined reaction temperature, and as a result, a C ₂₊ hydrocarbon compound in which some or all of methane is paired may be produced.

In another aspect, the present disclosure provides a method for oxidative dimerization of methane, which includes preparing a hydrocarbon compound containing two or more carbon atoms from methane by adding the catalyst for oxidative dimerization of methane to methane.

In an exemplary embodiment, the method includes: introducing a mixed gas including methane, oxygen and an inert gas into the reactor; and adding a catalyst for oxidative dimerization of methane in the reactor to perform oxidative dimerization of methane.

In an exemplary embodiment, the methane and oxygen may be mixed in a volume ratio of 1:1 to 10:1.

In an exemplary embodiment, the inert gas may be nitrogen.

In an exemplary embodiment, the oxidation dimerization reaction of methane is 550 °C or higher, 575 °C or higher, 600 °C or higher, 625 °C or higher, 650 °C or higher, 675 °C or higher, or 700 °C or higher, and 750 °C or lower, 725 °C or lower , it may be preferable to carry out at a temperature of 700 °C or less, 675 °C or less, or 650 °C or less. Accordingly, there is an effect of preventing the oxidative dimerization reaction activity of methane from being insignificant or the _{yield of C 2+} hydrocarbons falling. For example, the oxidative dimerization reaction of methane is carried out at 625 to 650 ° C. or 650 to 675 ° C. of methane. An excellent effect may be exhibited in terms of conversion rate and _{selectivity of C 2+ hydrocarbons.}

In an exemplary embodiment, the oxidative dimerization reaction of methane may be carried out at a gas hourly space velocity (GHSV) ^{of 5,000 to 15,000 h -1 .}

In an exemplary embodiment, the reactor is a continuous reactor, and a part for introducing a gas mixture including methane, oxygen, and inert gas to the reactor, a reactor filled with a catalyst and zirconia beads, and a high temperature furnace for adjusting the temperature of the reactor (Furnace), a water trap, and a gas chromatography system to detect the product.

1 shows a continuous reactor that can be used as an embodiment of the present specification.

In an exemplary embodiment, the continuous reactor includes a storage device 10 for methane, oxygen, and inert gas, a device 20 for mixing methane, oxygen, and inert gas, and a quartz tube reactor 30 to which a heating device is connected, the reaction It may include a cooling device 40 for cooling and collecting the post product and a gas chromatography device 50 for analyzing the final product.

Hereinafter, the present disclosure will be described in more detail through examples. These examples are only for illustrating the present disclosure, and it will be apparent to those of ordinary skill in the art that the scope of the present disclosure is not to be construed as being limited by these examples.

Example One.

22.4 mL of ethylene glycol and 7.6 mL of titanium isopropoxide were mixed and stirred for about 1 hour. After that, 20 mL of distilled water and 19.3 g of citric acid were sequentially added, but each was stirred for about 1 hour. Calcium nitrate tetrahydrate (calcium nitrate tetrahydrate) 6.0 g, strontium nitrate (strontium nitrate) 5.3 g and barium nitrate (barium nitrate) 6.6 g were mixed in the solution, respectively, and stirred for 1 hour. In addition, strontium nitrate (strontium nitrate) 4.3 g and barium nitrate (barium nitrate) 1.3 g was mixed with the solution and stirred for 1 hour to dope the perovskite structure with strontium and barium. The mixed solution was stirred for about 12 to 15 hours to prepare a catalyst. The prepared gel-form mixed solution was dried under an air atmosphere at 250° C. for 24 hours, and then calcined at 900° C. for 8 hours to prepare a catalyst for oxidation dimerization of methane having a perovskite structure (see Table 1 below). ).

Example 2.

2.0 g of the catalyst having a perovskite structure prepared in Example 1 was mixed with 15 mL of distilled water and stirred for 2 hours. Calcium nitrate tetrahydrate (calcium nitrate tetrahydrate) 0.8 in 5 mL of distilled water so that calcium oxide (CaO), strontium oxide (SrO) and barium oxide (BaO) can be supported on the perovskite structure in a weight ratio of 1:10 g, strontium nitrate (strontium nitrate) 0.4 g and barium nitrate (barium nitrate) 0.3 g were mixed, respectively. after. After stirring for 1 hour, the stirred solution was put into a solution containing the catalyst having the perovskite structure and stirred for 4 hours. The prepared mixed solution was dried under an air atmosphere at 105° C. for 6 hours, and then calcined at 900° C. for 8 hours to prepare a catalyst for oxidation dimerization of methane (see Table 1 below).

test example One.

The oxidation dimerization reaction of methane was performed using a continuous reactor with the catalyst prepared in Examples 1 and 2 above. The reaction temperature was fixed at 650 °C (reaction conditions; reaction time (time on stream, TOS) = 0.5-3 hours, total flow = 30 mL/min, methane: oxygen: nitrogen = 18: 6: 6 volume ratio, GHSV = 10,000 h ^-1 , catalyst volume = 0.18 mL). The gas mixture obtained after the reaction was analyzed using gas chromatography.

Table 1 below shows the reaction results for the various catalysts prepared in Examples 1 and 2 above.

Catalyst Methane Conversion (%) C ₂₊ hydrocarbon selectivity (mol%) C ₂₊ hydrocarbon yield
(mol%) Oxygen Conversion (%) CaTiO ₃ 9.0 0.5 0.04 11.9 SrTiO ₃ 15.5 9.1 1.42 79.6 BaTiO ₃ 4.5 5.4 0.25 21.7 BaSrTiO ₃ 16.6 1.6 0.27 69.2 1:10 weight% SrO/CaTiO ₃ 10.2 18.3 1.88 30.2 BaO/CaTiO ₃ 25.8 39.3 10.13 96.5 CaO/SrTiO ₃ 19.7 12.7 2.51 66.5 BaO/SrTiO ₃ 26.9 37.0 9.97 96.5 CaO/BaTiO ₃ 28.7 47.1 13.52 98.0 SrO/BaTiO ₃ 14.3 15.9 2.27 63.9

As a result, it was confirmed that, compared to a catalyst having a perovskite structure, a catalyst using the same as a support and supporting an alkaline earth metal oxide _{exhibited significantly higher methane conversion and C 2+} hydrocarbon selectivity.

In particular, the barium oxide (BaO), calcium titanate (Calcium titanate, CaTiO ₃₎ or strontium titanate (Strontium titanate, SrTiO ₃₎ each of the supported catalyst and the calcium oxide (CaO) is barium titanate (Barium titanate, BaTiO ₃ in _{), it was confirmed that the methane conversion rate and the C 2+} hydrocarbon selectivity were greatly increased in the catalyst supported in ), thereby accelerating the oxidation dimerization reaction of methane.

In the case of a catalyst prepared by supporting the calcium oxide (CaO) to barium titanate (Barium titanate, BaTiO _3), when subjected to the methane sanhwayi dimerization reaction at a temperature condition of 650 ℃ of conversion and C ₂₊ hydrocarbons in the methane The selectivity was greatly improved and it was confirmed that the oxidation dimerization reaction of methane was effectively carried out even at a low temperature as it showed _{the highest C 2+ hydrocarbon yield.}

Further, the perovskite when a barium (Ba) in the structure hayeoteul compared with BaSrTiO ₃ catalyst contained in the doping method, a perovskite structure, barium (Ba) is BaO / SrTiO ₃ catalyst, which is supported in the form of oxide in showed remarkably high methane conversion and C ₂₊ hydrocarbon selectivity. Accordingly, it was confirmed that the oxidation dimerization reaction activity of methane can be greatly improved by supporting the alkaline earth metal oxide on the support of the perovskite structure.

Above, specific parts of the present disclosure have been described in detail, for those of ordinary skill in the art, these specific techniques are only preferred embodiments, and it is clear that the scope of the present disclosure is not limited thereby. something to do. Accordingly, it is intended that the substantial scope of the present disclosure be defined by the appended claims and their equivalents.

10: Methane, oxygen, inert gas storage device
20: methane, oxygen, inert gas mixing device
30: Quartz tube reactor with heating device connected
40: cooling device for cooling and collecting the product after the reaction
50: gas chromatography apparatus for analyzing the final product

Claims (11)

support of perovskite structure; and
comprising an alkaline earth metal oxide supported on the support;
The perovskite structure has the formula ABO ₃ , wherein A is any one selected from Ca, Sr and Ba, B is Ti,
In the above formula, when A is Ca, the alkaline earth metal oxide is barium oxide,
In the above formula, when A is Sr, the alkaline earth metal oxide is barium oxide,
In the above formula, when A is Ba, the alkaline earth metal oxide is calcium oxide, a catalyst for oxidation dimerization of methane.
delete delete The method of claim 1,
The catalyst is, the calcium oxide is supported on barium titanate, the catalyst for oxidation dimerization of methane.
The method of claim 1,
The catalyst includes an alkaline earth metal oxide and a support in a weight ratio of 1: 5 to 1: 15, a catalyst for oxidation dimerization of methane.
The method of claim 1,
The catalyst is a catalyst for oxidation dimerization of methane, in which an alkaline earth metal precursor aqueous solution is mixed with an aqueous solution of a support having a perovskide structure and the alkaline earth metal is supported on a support having a perovskite structure in the form of an oxide.
The method of claim 1,
The catalyst is _{to prepare a C 2+} hydrocarbon compound from methane, a catalyst for oxidation dimerization of methane.
8. The method of claim 7,
The C ₂₊ hydrocarbon compound is ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ) and acetylene (C ₂ H ₂ ) For the oxidation dimerization reaction of methane comprising at least one selected from the group consisting of catalyst.
The oxidative dimerization of methane comprising preparing a hydrocarbon compound containing two or more carbon atoms from methane by adding the catalyst for the oxidative dimerization reaction of methane according to any one of claims 1 to 8 to methane reaction method.
10. The method of claim 9,
The method comprises the steps of: introducing a mixed gas containing methane, oxygen and an inert gas into the reactor; and
A method for oxidative dimerization of methane, comprising the step of adding a catalyst for oxidative dimerization of methane to a reactor to perform oxidative dimerization of methane.
11. The method of claim 10,
The oxidation dimerization reaction of methane is carried out at 550 to 750 ° C., the oxidation dimerization reaction method of methane.

Images