Manufacturing method of manganese adsorbent for desulfurization

Abstract

To provide: an adsorbent for desulfurization in which a composite oxide comprising manganese, copper and potassium is supported on an alumina or zeolite carrier; a method for manufacturing the same; and a method for adsorbing organic sulfur at room temperature by using the same.SOLUTION: In a manganese-based adsorbent for desulfurization, a potassium-manganese-copper composite oxide is supported on a carrier having an acidic point. The carrier is proton-form zeolite, pseudo-boehmite, or a mixture of proton-form zeolite and pseudo-boehmite. The content of the potassium-manganese-copper composite oxide is such that the potassium content is 1-3 wt.%, the manganese content is 60-85 wt.%, and the copper content is 5-15 wt.%, based on the total weight of the adsorbent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a manganese-based adsorbent for desulfurization, and more specifically, to a manganese-based adsorbent having a structure in which a composite oxide of manganese, copper, and potassium is supported on an alumina or zeolite carrier. The electrical characteristics of the adsorbent have been confirmed to change depending on the interaction between the carrier and the manganese-copper-potassium composite oxide. The present invention relates to a manganese-based adsorbent for adsorptive desulfurization that is effective in removing sulfur compounds such as tertiary butyl mercaptan (TBM) at room temperature even when it contains small amounts of manganese and copper. [Background technology]

[0002] A fuel cell is a power generation system that converts the chemical energy of hydrogen and oxygen contained in hydrocarbon substances such as methanol, ethanol, and natural gas into electrical energy. In a fuel cell's fuel processing device, a catalyst is used to reform hydrocarbon fuel gas to generate hydrogen. However, hydrocarbons typically contain sulfur compounds, which are poisons, so these must be removed before reforming. In particular, city gas, which is used as fuel for fuel cells, contains tertiary butyl mercaptan (TBM), a sulfur compound that acts as an odorant, so removing these sulfur compounds is essential for use in fuel cells. Summary of the Invention [Problem to be solved by the invention]

[0003] Although various adsorbents are available for removing sulfur compounds such as TBM from fuel gases, there is still a need for adsorbents with high adsorption properties at room temperature.

[0004] A first object of the present invention is to provide a manganese-based adsorbent for desulfurization that can efficiently remove sulfur compounds with small amounts of active metals, that is, manganese and copper.

[0005] A second object of the present invention is to provide a method for producing a manganese-based adsorbent for desulfurization.

[0006] A final object of the present invention is to provide a desulfurization method for removing sulfur compounds using a manganese-based desulfurization adsorbent. [Means for solving the problem]

[0007] In order to achieve the above technical objectives, the present invention provides a manganese-based adsorbent for adsorptive desulfurization, in which a manganese-copper-potassium composite oxide is supported on a carrier having acid sites.

[0008] Preferably, the support comprises a zeolite or alumina, more preferably proton form zeolite Y (HY-Zeolite) or pseudo-boehmite alumina. [Effects of the Invention]

[0009] According to the present invention, zeolite Y or pseudoboehmite alumina interacts with the composite oxide through a unique chemical bond, thereby exhibiting adsorption properties not observed in clay or crystalline alumina. The content of the support is 10 to 25 wt% based on the total weight of the adsorbent. In addition to improving the dispersibility of the supported composite oxide, the support also changes the electrical properties of the composite oxide, increasing its adsorption strength for sulfur compounds and improving adsorption performance. Without being limited by theory, it is understood that as electrons are transferred from the composite oxide to the support due to the influence of the support, the adsorption strength of electron-deficient manganese and copper metals for sulfur compounds is enhanced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graph showing the results of room temperature adsorption of TBM (tert-butyl mercaptan) by adsorbents according to examples and comparative examples of the present invention. [Figure 2]1 is a graph showing the results of UV-visible spectroscopy analysis of adsorbents according to examples and comparative examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] As used herein, the term "supported" refers to the phenomenon in which an active metal is deposited, impregnated, or incorporated onto the surface of a support or within the pores of the support, and can be used interchangeably with the term "coated."

[0012] The metal oxides supported on the carrier are potassium oxide, manganese oxide, and copper oxide. In this specification, manganese oxide and copper oxide are also referred to as active metals. The metal oxides can be impregnated sequentially into the carrier. The impregnation order does not determine the adsorption performance, but impregnation with potassium precursor, followed by manganese and copper precursors is preferred. The metal oxides are supported on the carrier by a redox reaction. A potassium precursor solution is used as the oxidizing agent, and manganese and copper precursor solutions are applied as the reducing agent. Adsorbents produced by the redox method have superior adsorption performance to adsorbents formed by other methods, such as solvent-deficient precipitation. The content of the metal oxides is 1 to 3 wt % for potassium oxide, 60 to 85 wt % for manganese oxide, and 5 to 15 wt % for copper oxide, based on the total weight of the adsorbent.

[0013] In order to achieve the second technical object, the present invention provides: a) preparing a mixture of a potassium precursor solution and a support; b) preparing a copper and manganese precursor solution; c) adding a copper and manganese precursor solution to the carrier mixture and aging the mixture to produce the adsorbent.

[0014] The carrier for improving the dispersibility of active metals and changing their electrical properties to improve their adsorption to sulfur compounds includes zeolite or alumina. Potassium precursors can be potassium permanganate as an oxidizing agent, while copper and manganese precursors, available in various forms such as nitrates, sulfates, and acetates, are used as reducing agents. The precursors form a composite oxide on the carrier through a redox reaction. According to the present invention, for optimal redox reaction, the reaction temperature in steps a), b), and c) is preferably 40 to 120°C, the stirring speed is preferably 60 to 500 rpm, and the addition rate in step c) is preferably 0.5 to 5 mL / min, and the aging time is preferably 2 to 50 hours, to carry out the redox reaction and form an optimal composite oxide.

[0015] After step c), the method may further include the steps of selectively obtaining the adsorbent through a filtration process and finally drying the obtained material.

[0016] To achieve the last technical objective, the present invention provides a desulfurization method in which fuel gas is passed through a manganese-based desulfurization adsorbent to remove sulfur compounds.

[0017] The method for desulfurization using a manganese-based adsorbent involves passing a fuel gas containing sulfur compounds through the manganese-based adsorbent of the present invention. Representative sulfur compounds include, but are not limited to, thiophenes, mercaptans, and disulfides. The temperature range suitable for desulfurization using a manganese-based adsorbent is 15 to 50°C. Since the adsorption performance of the adsorbent decreases as the ambient temperature increases, it is preferable to use the adsorbent at temperatures below 30°C.

[0018] The configuration and effects of the present invention will be described in more detail below using specific examples and comparative examples. However, these examples are merely intended to provide a clearer understanding of the present invention and are not intended to limit the scope of the present invention.

[0019] Example 1 A mixed aqueous solution of copper nitrate and manganese acetate was prepared by dissolving 6.14 g of copper nitrate trihydrate and 23.7 g of manganese acetate tetrahydrate in 67 mL of deionized water (Aqueous Solution A). Separately, 12.7 g of potassium permanganate was dissolved in 67 mL of deionized water, and then 3.4 g of pseudoboehmite alumina, which had been previously dehydrated at 120°C, was added to prepare an aqueous solution (Aqueous Solution B). While stirring Aqueous Solution B at 60°C, Aqueous Solution A was added to Aqueous Solution B at a rate of 3 mL / min. Stirring was continued for an additional 6 hours to form a precipitate and allow it to mature. The precipitate was then filtered, washed with deionized water, collected, and dried overnight at 120°C. The dried precipitate was pulverized to obtain Adsorbent 1.

[0020] <Example 2> A mixed aqueous solution of copper nitrate and manganese acetate was prepared by dissolving 6.14 g of copper nitrate trihydrate and 23.7 g of manganese acetate tetrahydrate in 67 mL of deionized water (Aqueous Solution A). Separately, 12.7 g of potassium permanganate was dissolved in 67 mL of deionized water, and then 3.4 g of hydrogen-form Y zeolite (SiO2 / Al2O3 = 5) was added to prepare an aqueous solution (Aqueous Solution B). While stirring Aqueous Solution B at 60 °C, Aqueous Solution A was added to Aqueous Solution B at a rate of 3 mL / min. Stirring was continued for an additional 6 hours to form a precipitate and allow it to mature. The precipitate was then filtered, washed with deionized water, collected, and dried overnight at 120 °C. The dried precipitate was crushed to obtain Adsorbent 2.

[0021] Comparative Example 1 was carried out to confirm the effect of the presence or absence of a carrier on adsorption performance.

[0022] <Comparative Example 1> A mixed aqueous solution of copper nitrate and manganese acetate was prepared by dissolving 6.14 g of copper nitrate trihydrate and 23.7 g of manganese acetate tetrahydrate in 67 mL of deionized water (aqueous solution A). Separately, an aqueous solution was prepared by dissolving 12.7 g of potassium permanganate in 67 mL of deionized water (aqueous solution B). While stirring aqueous solution B at 60°C, aqueous solution A was added to aqueous solution B at a rate of 3 mL / min. Stirring was continued for an additional 6 hours to form a precipitate and allow it to mature. The precipitate was then filtered, washed with deionized water, recovered, and dried overnight at 120°C. The dried precipitate was pulverized to obtain adsorbent 3.

[0023] Comparative Examples 2 and 3 were carried out to confirm the effect of the adsorption performance on the presence or absence of chemical bonding between the composite oxide and the carrier.

[0024] <Comparative Example 2> Adsorbent 4 was obtained by physically mixing Adsorbent 3 produced in Comparative Example 1 with 3.4 g of pseudoboehmite alumina from which moisture had been removed at 120°C in advance.

[0025] <Comparative Example 3> Adsorbent 5 was obtained by physically mixing Adsorbent 3 prepared in Comparative Example 1 with 3.4 g of hydrogen form Y zeolite, from which moisture had been removed at 120°C in advance.

[0026] Finally, in order to confirm the effect of the manufacturing method on the adsorption performance, Comparative Examples 4 and 5 were carried out using the solid phase precipitation method instead of the oxidation-reduction reaction.

[0027] <Comparative Example 4> A mixture of 6.14 g of copper nitrate trihydrate, 43.7 g of manganese acetate tetrahydrate, and 3.4 g of pseudoboehmite alumina, which had been previously dehydrated at 120°C, was prepared by grinding and mixing. 33.8 g of sodium bicarbonate was added to the mixture, which was then ground and mixed to produce a uniform mixture. 18.5 g of deionized water was then added to cause precipitation. After the addition of deionized water, the mixture was ground and mixed until no more bubbles were generated, producing a precipitate. The precipitate was then aged, washed with deionized water, collected, and dried overnight at 120°C. The dried precipitate was ground to obtain adsorbent 6.

[0028] <Comparative Example 5> A mixture of 6.14 g of copper nitrate trihydrate, 43.7 g of manganese acetate tetrahydrate, and 3.4 g of hydrogen-form Y zeolite, which had been previously dehydrated at 120°C, was prepared by crushing and mixing. 33.8 g of sodium bicarbonate was added to the mixture, which was then crushed and mixed to produce a uniform mixture. 18.5 g of deionized water was then added to cause precipitation. After the addition of the deionized water, the mixture was crushed and mixed until no more bubbles were generated, producing a precipitate. The precipitate was then aged, washed with deionized water, collected, and dried overnight at 120°C. The dried precipitate was crushed to obtain adsorbent 7.

[0029] To evaluate adsorption performance, 0.1 g of the adsorbents obtained in the examples and comparative examples were dehydrated at 120°C and then placed in a 15 mm diameter quartz reactor. The interior was then switched to a nitrogen atmosphere, and 175 ppm TBM (N balance) gas was flowed at 39 sccm to evaluate adsorption performance. The adsorption performance was evaluated by measuring the time from the moment TBM was first flowed to the moment sulfur components were detected using PFPD GC, and the amount of sulfur adsorption was calculated.

[0030] Figure 1 shows the TBM room temperature adsorption results for adsorbents according to examples and comparative examples of the present invention. It can be seen that Adsorbents 1 and 2 exhibited improved adsorption capacity compared to Adsorbent 3 (Comparative Example 1), which did not contain a carrier. Referring to Figure 2, the adsorbent of Comparative Example 1 had a band gap energy of approximately 1.8 eV. However, in Examples 1 and 2, which use an acidic carrier, electrons shift from the composite oxide to the carrier, further increasing the band gap energy, which is believed to result in increased adsorption strength. Furthermore, the adsorbents of Comparative Examples 2 and 3, which contain a carrier but lack a chemical bond with the composite oxide, exhibited smaller band gap energies than those of Examples 1 and 2, demonstrating lower adsorption performance.

[0031] The manganese-based adsorbent for desulfurization of the present invention, unlike conventional adsorbents for desulfurization, contains a carrier that changes the electrical state of the active metal, thereby inducing an electron-deficient state of the active metal and improving its adsorption ability for sulfur compounds. Therefore, the manganese-based adsorbent for desulfurization of the present invention has the effect of efficiently removing sulfur compounds from fuel gas at room temperature even when a small amount of active metal is used.

Claims

[Claim 1] A method for producing a manganese-based adsorbent for desulfurization, comprising: a) preparing a mixture of a potassium precursor solution as an oxidizing agent and a support having acid sites; b) preparing a copper and manganese precursor solution as a reducing agent; c) adding copper and manganese precursor solutions to the mixture and aging to produce an adsorbent. A method for producing a manganese-based adsorbent, comprising:

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