KR20120081465A - Method for manufacturing a porous perovskite catalyst of hollow fiber-type and the porous perovskite catalyst of hollow fiber-type - Google Patents

Abstract

PURPOSE: A method for manufacturing a porous hollow fibrous perovskite catalyst and the catalyst are provided to improve the hydrogen conversion rate of hydro carbon and to activate a vapor reforming reaction, an autothermal reforming reaction, a partial oxidization reforming reaction, and a carbon dioxide reforming reaction. CONSTITUTION: A method for manufacturing a porous hollow fibrous perovskite catalyst includes the following: the precursors of metals, which form a perovskite catalyst, are dissolved to obtain a perovskite catalyst precursor solution; activated carbon fiber is treated with acid; the carbon fiber is coated with the precursor solution; and the coated carbon fiber is heated at a temperature between 700 and 100 degrees Celsius to be combusted. The precursors of the metals are selected from a group including the nitrate, the cyanide salt, the alkoxide salt, the hydrochloride, and the oxide compound of the metals.

Description

Method for manufacturing a porous perovskite catalyst of hollow fiber-type and the porous perovskite catalyst of hollow fiber-type}

The present invention relates to a process for preparing a hydrocarbon reforming catalyst and to a hydrocarbon reforming catalyst produced by such a process. More specifically, the present invention relates to a method for producing a porous hollow fibrous perovskite catalyst and a porous hollow fibrous perovskite catalyst produced by such a method.

Recently, new energy technologies have been in the spotlight due to environmental problems, and fuel cells have attracted attention as one of these new energy technologies. Fuel cells convert chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen, and have a high energy use efficiency. Therefore, practical researches are being actively conducted for civil, industrial or automobile use.

The hydrogen sources include methanol, liquefied natural gas mainly composed of methane, urban gas mainly composed of natural gas, synthetic liquid fuel composed of natural gas, and petroleum hydrocarbons such as naphtha or diesel. ought.

When hydrogen is produced using petroleum hydrocarbons, the hydrocarbons are generally steam reformed in the presence of a catalyst. In the steam reforming reaction, a catalyst in which a ruthenium component is supported as an active ingredient on a carrier has been studied in the past. Catalysts in which the ruthenium component is supported as an active ingredient on the carrier have a relatively high activity and have the advantage that carbon precipitation is suppressed even under a low vapor / carbon ratio operating condition. Application to batteries is expected.

On the other hand, after the discovery of the cocatalyst effect on the ruthenium catalyst of cerium oxide or zirconium oxide catalyst, research on catalysts based on cerium oxide or zirconium oxide and ruthenium has also been conducted. In addition to the ruthenium component, studies on platinum component, rhodium component, palladium component, iridium component and nickel component catalysts have been conducted as active components. However, a disadvantage is that the activity of the hydrocarbon as a steam reforming catalyst is not sufficient yet, and a large amount of carbon is precipitated during the reforming.

In order to produce hydrogen, in addition to steam reforming, research has been conducted on magnetic thermal reforming, partial oxidation reforming, and carbon dioxide reforming, and in general, all the reforming reactions can be generally performed using the same reforming catalyst. It is known.

However, ruthenium component, platinum component, rhodium component, palladium component, iridium component and nickel component have been studied as catalysts for the self thermal reforming treatment, partial oxidation reforming treatment and carbon dioxide reforming treatment, but the activity is known to be insufficient. have.

The present invention has been made to solve the above problems of the prior art, and by dramatically increasing the specific surface area of the catalyst by a simple method, all of the steam reforming, magnetic thermal reforming, partial oxidation reforming and carbon dioxide reforming It is an object of the present invention to provide a method for preparing a porous hollow fibrous perovskite catalyst that enables increased catalyst activity and improved hydrocarbon conversion in a reaction.

In addition, an object of the present invention is to provide a porous hollow fibrous perovskite catalyst prepared by the above method.

The present invention,

(a) dissolving the precursors of the metals constituting the perovskite catalyst of general formula ABO ₃ to prepare a perovskite catalyst precursor solution;

(b) treating the activated carbon fibers with an acid;

(c) coating the acid treated activated carbon fibers with the perovskite catalyst precursor solution; And

(d) it provides a method for producing a porous hollow fibrous perovskite catalyst comprising the step of burning the activated carbon fiber by heating the coated activated carbon fiber to 700-100 ℃.

The present invention also provides a porous hollow fibrous perovskite catalyst prepared by the above production method.

According to the production method of the present invention, the perovskite catalyst can be prepared in a porous hollow fiber by a simple method, and the porous hollow fibrous perovskite catalyst has a markedly increased specific surface area. Therefore, the porous hollow fibrous perovskite catalyst prepared by the production method of the present invention provides excellent activity and hydrogen conversion rate of hydrocarbons in all reactions of steam reforming, magnetic thermal reforming, partial oxidation reforming and carbon dioxide reforming. do.

1 is a photograph showing the form of a porous hollow fibrous perovskite catalyst prepared according to the present invention.
Figure 2 is a graph showing the test results of Test Example 1 to demonstrate the excellent hydrogen conversion of the porous hollow fibrous perovskite catalyst of the present invention.

The present invention,

(a) dissolving the precursors of the metals constituting the perovskite catalyst of general formula ABO ₃ to prepare a perovskite catalyst precursor solution;

(b) treating the activated carbon fibers with an acid;

(c) coating the acid treated activated carbon fibers with the perovskite catalyst precursor solution; And

(D) a method for producing a porous hollow fibrous perovskite catalyst comprising the step of burning the activated carbon fiber by heating the coated activated carbon fiber to 700-100 ℃.

The production method of the present invention can provide a perovskite catalyst having a porous hollow fibrous structure by a simple method, and the perovskite catalyst prepared by this method increases the specific surface area significantly, and thus water vapor In all reactions of reforming, magnetic thermal reforming, partial oxidation reforming, and carbon dioxide reforming, the activity of the catalyst and the hydrogen conversion rate of hydrocarbons are also greatly improved. .

In Formula ABO ₃ of step (a), A is at least one metal selected from the group consisting of sodium, potassium, rubidium, silver, magnesium, calcium, strontium, barium, lead, lanthanum, cesium, bismuth, and the like. It can consist of

The B may be composed of at least one metal selected from the group consisting of lithium, copper, magnesium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, platinum, tungsten, tantalum, niobium, ruthenium.

Precursors of the metals constituting the perovskite catalyst in step (a) may be nitrates, cyanide salts, alkoxide salts, hydrochloride salts, oxide compounds and the like of the metal constituting the perovskite catalyst.

In particular, the precursor of the metals constituting the perovskite catalyst is preferably composed of lanthanum nitrate, chromium nitrate and ruthenium nitrosyl nitrate.

The lanthanum nitrate, chromium nitrate, and ruthenium nitrosyl nitrate are preferably molar ratios of lanthanum, chromium, and ruthenium ions contained in the perovskite catalyst precursor solution. Is 1: 0.80-0.99: 0.01-0.20, more preferably 1: 0.90-0.99: 0.01-0.10.

Examples of the solvent used in the preparation of the perovskite catalyst precursor solution in step (a) include N, N-dimethylformamide (DMF), N, N-dimethylacetamide DMAC, ethylenediamine, distilled water, and the like. It is preferable to use distilled water. The solvent is preferably included in 5 to 50% by weight relative to the total weight of the perovskite catalyst precursor solution. When the content of the solvent is included in less than 5% by weight, the viscosity of the solution is so high that the coating of the perovskite catalyst precursor is too thick, if it exceeds 50% by weight the viscosity of the solution is too low to coat properly.

The perovskite catalyst precursor solution in step (a) may be prepared by further comprising a chelating agent, the chelating agent may be citric acid, malic acid, formic acid, acetic acid and the like. In addition, the chelating agent may further include an organic material such as polyvinyl alcohol (PVA).

In step (a), the perovskite catalyst precursor solution may further include silica, and the silica may be included in the form of a solution containing a surfactant such as cetyltriammonium chloride and cetyltriammonium bromide.

The activated carbon fiber of step (b) is a carbon fiber prepared by a known method by activating treatment by a known method, although not particularly limited, the average length of 1nm ~ 10㎛ and 0.1nm ~ 10μm average It is preferred to have a diameter. In addition, it is possible to control the aspect ratio of the prepared fibrous catalyst by adjusting the diameter of the carbon fiber used.

The shape of the activated carbon fiber is not particularly limited and may be linear, branched, or web or net.

The acid treatment of the activated carbon fiber is carried out to increase the coating efficiency of the perovskite catalyst precursor solution, and the acid treatment method is not particularly limited. For example, the activated carbon fiber may be impregnated by dipping in an acid such as nitric acid, sulfuric acid, hydrochloric acid, acetic acid, or the like for about 1-5 hours.

The coating method of step (c) is not particularly limited, and may be used, such as dipping, wash coating and spraying method, by which the perovskite catalyst precursor solution is acid treated, the surface of the activated carbon fiber Is impregnated.

Combustion of the activated carbon fiber of step (d) is a process for producing a hollow fiber phase by removing the activated carbon fiber. The combustion is preferably made in an air atmosphere, it may be made by heat treatment at 700-1000 ℃ in a heating furnace, more preferably at 800-900 ℃ heat treatment.

The present invention also relates to a porous hollow fibrous perovskite catalyst which is prepared by the above method.

The porous hollow fibrous perovskite catalyst prepared by the method of the present invention has a hollow structure formed by removing activated carbon fibers, and has a porous structure since the porous structure of the activated carbon fiber surface is maintained in the catalyst as it is. As the appearance of the activated carbon fiber is maintained as it is, the fibrous structure is obtained.

Therefore, the porous hollow fibrous perovskite catalyst of the present invention has a high specific surface area, and for this reason, mass transfer is required in all reactions of steam reforming, magnetic thermal reforming, partial oxidation reforming, and carbon dioxide reforming. Provide a facilitating effect.

In addition, the most problematic problem in the self-thermal reforming, partial oxidation reforming, and carbon dioxide reforming reaction is the formation of coke generated during the reaction, and when the coke is formed on the catalyst, the pressure of the reactor rises and the performance of the catalyst occurs. Is lowered. However, since the porous hollow fibrous perovskite catalyst of the present invention is porous, the pressure drop due to coke formation is also partially reduced.

The porous hollow fibrous perovskite catalyst of the present invention is represented by the general formula ABO ₃ , wherein A is a group consisting of sodium, potassium, rubidium, silver, magnesium, calcium, strontium, barium, lead, lanthanum, cesium, bismuth, and the like. May be composed of one or more metals selected from

The B may be composed of at least one metal selected from the group consisting of lithium, copper, magnesium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, platinum, tungsten, tantalum, niobium, ruthenium.

In the porous hollow fibrous perovskite catalyst of the present invention, A is lanthanum, and B is more preferably composed of chromium and ruthenium. The molar ratio of lanthanum, chromium and ruthenium is preferably 1: 0.80-0.99: 0.01-0.20, more preferably 1: 0.90-0.99: 0.01-0.10.

In addition,

A reformer having a porous hollow fibrous perovskite catalyst is provided, and a fuel cell device including the reformer is provided.

Hereinafter, the hydrocarbon reforming method using the porous hollow fibrous perovskite catalyst of the present invention will be described.

First, the steam reforming reaction of a hydrocarbon using the catalyst of the present invention will be described. Examples of the raw hydrocarbon used for the reaction include linear or branched saturated aliphatic hydrocarbons having 1 to 16 carbon atoms, such as methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, And alicyclic saturated hydrocarbons such as cyclohexane, methyl cyclohexane and cyclooctane, monocyclic and polycyclic aromatic hydrocarbons, various gases such as city gas, LPG, naphtha and kerosene.

In general, when sulfur content is present in these raw hydrocarbons, it is preferable to desulfurize the sulfur content until it becomes 0.1 ppm or less through the desulfurization process.

The reaction conditions can usually determine the amount of hydrocarbons and the amount of water vapor so that the vapor / carbon (molar ratio) is 1.5 to 10, preferably 1.5 to 5, more preferably 2 to 4. By adjusting the vapor / carbon (molar ratio) in this manner, hydrogen gas can be efficiently obtained.

The reaction temperature is usually 200 to 900 ° C, preferably 250 to 900 ° C, more preferably 300 to 800 ° C. The reaction pressure is usually 0 to 3 MPa-G, preferably 0 to 1 MPa-G. When using kerosene or a hydrocarbon having a boiling point higher than that as a raw material, it is preferable to perform steam reforming by maintaining the inlet temperature of the steam reforming catalyst layer at 630 ° C or lower, preferably 600 ° C or lower. If the inlet temperature exceeds 630 ° C., thermal decomposition of the hydrocarbon may be promoted, radicals may be generated, and carbon may precipitate on the catalyst or reaction tube walls, making operation difficult. The catalyst bed outlet temperature is not particularly limited, but is preferably in the range of 650 to 800 ° C. If it is less than 650 ° C, there is a concern that the amount of hydrogen generated is not sufficient, and if it exceeds 800 ° C, a heat-resistant material may be required for the reaction apparatus, which is economically undesirable.

In addition, a little water vapor is added, and the reaction temperature is set low and the reaction pressure is set low.

The magnetothermal reforming reaction takes place in the same reactor or in a continuous reactor where the oxidation of hydrocarbons and the reaction between hydrocarbons and water vapor occur. In the reaction conditions for producing hydrogen, the reaction temperature is usually 200 to 1,300 ° C, preferably 400 to 1,200 ° C, more preferably 500 to 900 ° C. The vapor / carbon (molar ratio) is usually 0.1 to 10, preferably 0.4 to 4, and the oxygen / carbon (molar ratio) is usually 0.1 to 1, preferably 0.2 to 0.8. The reaction pressure is usually 0 to 10 MPa-G, preferably 0 to 5 MPa-G, more preferably 0 to 3 MPa-G. The same hydrocarbons as the steam reforming reaction are used.

In the partial oxidation reforming reaction, a partial oxidation reaction of a hydrocarbon occurs, and the reaction temperature is usually 350 to 1,200 ° C, preferably 450 to 900 ° C under reaction conditions for producing hydrogen. Oxygen / carbon (molar ratio) is usually 0.4 to 0.8, preferably 0.45 to 0.65. The reaction pressure is usually 0 to 30 MPa-G, preferably 0 to 5 MPa-G, more preferably 0 to 3 MPa-G. The same hydrocarbon is used as the steam reforming reaction.

In the carbon dioxide reforming reaction, a reaction between a hydrocarbon and a carbon dioxide gas occurs, and the reaction temperature is usually 200 to l, 300 ° C, preferably 400 to 1,200 ° C, more preferably 500 to 900 ° C under the reaction conditions for producing hydrogen. The carbon dioxide gas / carbon (molar ratio) is usually 0.1 to 5, preferably 0.1 to 3. When steam is added, steam / carbon (molar ratio) is usually 0.1 to 10, preferably 0.4 to 4. When oxygen is supplied, the oxygen / carbon (molar ratio) is usually 0.1 to 1, preferably 0.2 to 0.8. The reaction pressure is usually 0 to 10 MPa-G, preferably 0 to 5 MPa-G, more preferably 0 to 3 MPa-G. Methane is usually used as a hydrocarbon, but the same one as used for steam reforming is used.

As the reaction system of the above-mentioned reforming reaction, either a continuous flow type or a batch type can be used, but continuous flow type is preferable. When the continuous flow type is used, the liquid space velocity (LHSV) of the hydrocarbon is usually 0.1 to 10 hr −1, preferably 0.25 to 5 hr −1. In addition, when gas, such as methane, is used as a hydrocarbon, a gas space velocity (GHSV) is 200-10000 hr <-1> normally.

The reaction format is not particularly limited and may be used in both a fixed bed, a movable bed and a fluidized bed, but a fixed bed is preferred.

The reactor type is not particularly limited, for example, a tubular reactor or the like can be used.

The catalyst of the present invention can be suitably used in a hydrogen production process of a fuel cell because hydrogen can be obtained by performing a steam reforming reaction, a magnetothermal reforming reaction, a partial oxidation reaction, a carbon dioxide reforming reaction of a hydrocarbon under the above conditions. .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by the following examples. The following examples can be appropriately modified and changed by those skilled in the art within the scope of the present invention.

Example 1 Preparation of Porous Hollow Fiber Perovskite Catalysts

The activated carbon fiber having an average length of 1 nm to 10 μm and an average diameter of 0.5 μm was immersed in 2M nitric acid solution and stirred at room temperature for 2 hours. The immersed activated carbon fiber was filtered, dried in an oven, and then immersed in 6M sulfuric acid solution, stirred at 75 ° C. for 2 hours, filtered, and then dried in an oven to obtain acid of activated carbon fiber. The treatment was completed.

43.3 g of lanthanum nitrate, 32 g of chromium nitrate, and 4 g of ruthenium nitrosyl nitrate were dissolved in 500 ml of distilled water to prepare a perovskite catalyst precursor solution.

The acid treated activated carbon fibers were immersed in the prepared perovskite catalyst precursor solution for 24 hours to impregnate the perovskite catalyst precursor and then filtered and dried. Thereafter, the activated carbon fiber, impregnated with the perovskite catalyst precursor, was calcined at 800 ° C. for 6 hours in a furnace to burn the activated carbon fiber to form a porous hollow fibrous perovskite catalyst, La ₁ Cr. _0.95 Ru _0.05 O ₃ was prepared.

Test Example 1: Evaluation of Hydrogen Conversion of Perovskite Catalyst

In order to evaluate the activity of the perovskite catalyst of the present invention, by using the porous hollow fibrous perovskite catalyst and grain perovskite catalyst prepared in Example 1, the autothermal reforming reaction of diesel ( Hydrogen conversion by autothermal reforming (ATR) was evaluated as follows:

Hydrogen conversion was calculated by measuring the carbon balance before and after the reaction.

% Conversion = (number of carbons in CO, CO ₂ , CH _{4 in} the reaction gas) / (number of carbons supplied to the reaction) * 100

As a result of the experiment, hydrogen conversion according to the molar ratio of O ₂ / C (C ₁₆ H ₃₄ ) is shown in FIG. 2. As can be seen from FIG. 2, the porous hollow fibrous perovskite catalyst of the present invention provides better hydrogen conversion compared to the grain perovskite catalyst.

Claims (10)

(a) dissolving the precursors of the metals constituting the perovskite catalyst of general formula ABO ₃ to prepare a perovskite catalyst precursor solution;
(b) treating the activated carbon fibers with an acid;
(c) coating the acid treated activated carbon fibers with the perovskite catalyst precursor solution; And
(D) a method of producing a porous hollow fibrous perovskite catalyst comprising the step of burning the activated carbon fiber by heating the coated activated carbon fiber to 700-100 ℃. The method according to claim 1, wherein in formula (ABO ₃ ) of the step (a)
A consists of one or more metals selected from the group consisting of sodium, potassium, rubidium, silver, magnesium, calcium, strontium, barium, lead, lanthanum, cesium and bismuth,
B is composed of at least one metal selected from the group consisting of lithium, copper, magnesium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, platinum, tungsten, tantalum, niobium and ruthenium Method for producing a porous hollow fibrous perovskite catalyst. The precursor of the metals constituting the perovskite catalyst in step (a) is selected from the group consisting of nitrates, cyanide salts, alkoxide salts, hydrochlorides and oxide compounds of the metals constituting the perovskite catalyst. Method for producing a porous hollow fibrous perovskite catalyst, characterized in that selected. The method of claim 3, wherein the precursors of the metals constituting the perovskite catalyst are lanthanum nitrate, chromium nitrate, and ruthenium nitrosyl nitrate. Method for producing hollow fibrous perovskite catalyst. The method of claim 4, wherein the lanthanum nitrate, chromium nitrate, and ruthenium nitrosyl nitrate are selected from lanthanum, chromium, and ruthenium ions in the perovskite catalyst precursor solution. A method for producing a porous hollow fibrous perovskite catalyst, characterized in that the molar ratio is 1: 0.80-0.99: 0.01-0.20. The solvent used in the preparation of the perovskite catalyst precursor solution in step (a) comprises N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC) and distilled water. A method for producing a porous hollow fibrous perovskite catalyst, characterized in that at least one member selected from the group. The method of claim 1, wherein the perovskite catalyst precursor solution in step (a) further comprises at least one selected from a chelating agent and silica. The method of claim 1, wherein the activated carbon fiber of step (b) has a mean length of 1 nm to 10 μm and an average diameter of 0.1 nm to 10 μm. The method of claim 1, wherein the coating of step (c) is performed by a method selected from dipping, wash coating, and spray methods. A porous hollow fibrous perovskite catalyst prepared by the method of any one of claims 1 to 9.

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