RU2448771C1 - Adsorbent desulphuriser for liquid phases - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to desulphurisation agents and use thereof. Described is a desulphurisation agent for liquid-phase adsorption desulphurisation, containing a metal oxide on which gold nanoparticles are deposited, having mean particle size of 50 nm or less. Described is a desulphurisation agent for liquid-phase adsorption desulphurisation, where said desulphurisation agent is fixed on a support element. Described is a desulphurisation method, which involves bringing said desulphurisation agent into contact with a liquid containing an organic compound which contains sulphur. Described is a method for reclamation of the desulphurisation agent, involving thermal treatment of the desulphurisation agent after desulphurisation in order to remove the sulphur-containing organic compound adsorbed on the desulphurisation agent. Described is a desulphurisation method, which involves bringing the desulphurisation agent, which is subjected to treatment and reclamation using the described method, into contact with a liquid containing an organic compound which contains sulphur.

EFFECT: described desulphurisation agent enables to remove sulphur compounds based on thiophenes to concentration lower than 10 ppm.

10 cl, 1 tbl, 7 dwg, 6 ex

Description

FIELD OF THE INVENTION

The present invention relates to a desulfurization agent for liquid phase adsorption desulfurization and to a desulfurization method that uses a desulfurization agent.

BACKGROUND

From the point of view of preventing environmental pollution, improving fuel efficiency for engines, adapting the fuel cell system for vehicles in the future and the like, there is a need to further reduce the sulfur concentration in liquid fuels such as gasoline, kerosene, light gas oil and the like. . Accordingly, the establishment of technologies for desulfurization of liquid fuels is an important problem.

Although the so-called sulfur-free fuel, having a sulfur concentration of about 10 ppm, is already supplied as a commercial product, there is currently a need for technology to further reduce sulfur concentration. In particular, the need is considered that the sulfur concentration in the fuel for fuel cells is 0.1 ppm. or less. Note that in the present description, the expression "ppm" indicates sulfur ppm massive. 1 million d refers to the case when 1 μg of sulfur is contained as an element in 1 g of liquid petroleum fuel.

As a method of reducing the sulfur concentration in liquid fuel, the method of producing liquid fuel uses exclusively a hydrodesulfurization method that uses a cobalt-molybdenum catalyst. However, among the various sulfur compounds contained in the liquid fuel, dibenzothiophene has a relatively low chemical activity during hydrogenation and thus has a negative tendency to remain in the liquid fuel even after treatment with hydrodesulfurization. In particular, 4,6-dimethyldibenzothiophene and the like having alkyl groups near the sulfur atom of dibenzothiophene have poor chemical activity on the surface of the catalyst due to steric hindrance and are considered compounds that are difficult to remove. Accordingly, attempts are being made to improve hydrodesulfurization catalysts, and other methods, such as oxidative desulfurization and adsorption desulfurization, are also being investigated.

The liquid phase adsorption desulfurization method is a method of adsorbing and removing sulfur compounds by creating a contact between the liquid fuel and the desulfurization agent, and the method can be carried out using a simple device. However, after the desulfurization agent reaches adsorption saturation, desulfurization can no longer be carried out, and after replacement, the adsorbent used cannot be reused. This creates the problem of generating large amounts of industrial waste. Thus, the regeneration and reuse of the desulfurization agents used is desirable; however, with respect to adsorption desulfurization agents for thiophene compounds, there are no known agents that can satisfy such properties.

Materials that are currently considered potential agents for liquid-phase adsorption desulfurization can be classified into four categories: activated carbon based material, metal oxide based material, zeolite based material and metal based material (see NPL 1). Of these, activated carbon can be widely used as a common adsorbent. Its specific surface area is very large (1000 m ² / g or more), and it has good ability to adsorb organic materials in general; however, selective adsorption with exceptional adsorption of organic materials containing sulfur cannot be expected. In addition, although thermal regeneration of activated carbon is ubiquitous, part of the activated carbon itself, unfortunately, decomposes during regeneration. If safety protocols are inadequate, activated carbon may ignite and accidental poisoning may occur due to the formation of carbon monoxide during decomposition of the adsorbed material.

Materials, such as iron oxide, zinc oxide and the like, are put into practical use as oxide-based desulfurization agents because they adsorb hydrogen sulfide. However, none of them reportedly show sufficient performance as an agent for adsorption of thiophene-based sulfur compounds.

Zeolite-based desulfurization agents have a large specific surface area (500 m ² / g or more), are thermally stable and have properties that can be easily changed by modification, such as ion exchange and the like. Accordingly, the use of zeolite-based desulfurization agents as adsorption desulfurization agents is an object of study. For example, Y-type zeolite ion exchanged with Cu or Ce (Cu-Y, Ce-Y) has been reported to be suitable as an adsorbent for thiophene-based compounds (see PTL 2 and 3 below). However, a method for regenerating adsorbents after desulfurization has never been reported. The experiments of the authors of the present invention confirm that the regeneration and reuse of adsorbents cannot be achieved using a conventional heating operation.

With respect to metal-based desulfurization agents, those types of sulfur compounds that can be adsorbed and removed efficiently are different depending on the types of metals used, and it is known that Ni-based desulfurization agents exhibit excellent performance for thiophene-based compounds. However, the desulfurization operation using the Ni-based desulfurization agent is very difficult, since the adsorption must be carried out by heating to a temperature of about 200 ° C after the agent is subjected to hydrogen reduction at high temperatures and a special stabilization treatment. In addition, after Ni forms a stable sulfide, regeneration is very difficult (see PTL 1 below).

A material for which noble metal nanoparticles are deposited on the surface of a metal oxide as a carrier is known to have high activity in various chemical reactions and is used as a catalyst for various chemical reactions. It is known that when such a noble metal catalyst is used, the sulfur compound is usually adsorbed on the active center of the noble metal catalyst and becomes poison for the catalyst. Accordingly, there are few reports of studies of noble metal catalysts such as Pt, Pd and the like for the purpose of desulfurization, compared with the number of reports of a cobalt-molybdenum catalyst. However, a recent report shows that a system in which platinum is applied, for example, to a zeolite, exhibits hydrodesulfurization activity (see NPL 4 below). In addition, although there has been a report of an attempt to control the performance of a platinum catalyst by hydrodesulfurization by adding gold to it, a material containing only gold as a noble metal has never been reported as a desulfurization catalyst.

Among sulfur compounds, alkanethiols (RSH) are especially known as regularly adsorbing on the surface of gold and forming a self-assembled monolayer (SAM). Over time, reports by Gao et al. in 1995 on the formation of SAM by polyalkylthiophene (see NPL 5 below), many researchers also confirm experimentally that thiophene forms SAM. Since the thiophene polymer could be used as a conductive polymer for electronic devices and the like, this is becoming an active area of research. With respect to simple thiophene or alkylthiophene, the phenomenon of adsorption on the surface of Au and this application have been investigated as described above. However, Au single crystals are used solely for the purpose of using the monolayer as SAM, and they are not used as adsorption desulfurization agents, since the adsorption value is small. There are no reports of adsorption of dibenzothiophene compounds, which are important as objects for desulfurization of liquid fuels.

BIBLIOGRAPHY

Patent Literature

PTL 1: Publication of Unexamined Japanese Patent Application No. 11-169601.

Non-Patent Literature

NPL 1: Japan Petroleum Energy Center, Engineering Planning Division, PETROTECH , 11 (2005), pp. 835-840.

NPL 2: Osamu Chiyoda, Shokubai (Catalysts & Catalysis), 47 (2005), p. 568.

NPL 3: M. Xue et al., J. Colloid Interf. Sci., 298 (2006), pp. 535-542.

NPL 4: M. Sugioka et al., J. Jpn. Petrol. Inst., 45 (2002), pp. 342-354.

NPL 5: Z. Gao et al., Synthetic Metalls, 75 (1995), pp. 5-10.

SUMMARY OF THE INVENTION

Technical problem

The present invention has been accomplished in terms of the above-described common technical problems. Its main task is to create an agent for desulfurization through liquid phase adsorption, which is effective for sulfur compounds contained in liquid fuel. More specifically, it provides a new desulfurization agent, where the agent can remove thiophene-based sulfur compounds that are difficult to remove sufficiently using conventional methods, to such an extent that the sulfur concentration is lower than 10 ppm, and the agent can then be reused using a simple method after desulfurization treatment.

Solution

The authors of the present invention have carried out extensive research to achieve the above objectives. As a result, they found that the metal oxide on which gold nanoparticles are deposited, which is known as a catalyst for various chemical reactions, acts as an adsorbent with good selectivity for organic compounds containing sulfur in liquid fuel. In particular, they found that thiophene-based sulfur compounds, which are difficult to remove using conventional methods to the extent that their concentration is sufficiently low, can also be adsorbed and removed to such an extent that their concentration is sufficiently low. In addition, they found that after adsorption treatment, the adsorbed sulfur compounds can be effectively removed by a simple heat treatment, and thus, the catalyst can be reused as an adsorbent. The present invention is based on these data.

Specifically, the present invention provides a desulfurization agent for liquid phase adsorption desulfurization and a desulfurization method using a desulfurization agent as described below.

1. A desulfurization agent for liquid phase adsorption desulfurization containing a metal oxide coated with gold nanoparticles having an average particle size of 50 nm or less.

2. The desulfurization agent in accordance with paragraph 1, which has a specific surface area of 1 m ² / g or more.

3. The desulfurization agent of liquid-phase adsorption desulfurization, where the metal oxide coated with gold nanoparticles in accordance with paragraph 1 is fixed on the carrier element.

4. The desulfurization agent in accordance with paragraph 1, where the processing objective is a liquid fuel containing an organic compound containing sulfur.

5. A method of desulfurization, comprising bringing the desulfurization agent in accordance with paragraph 1 into contact with a liquid containing an organic compound containing sulfur.

6. The desulfurization method in accordance with paragraph 5, where the purpose of the treatment is a liquid fuel containing an organic compound containing sulfur.

7. The desulfurization method in accordance with paragraph 6, where the liquid fuel serving as an object of processing contains an organic compound containing a thiophene ring.

8. The desulfurization process according to paragraph 7, wherein the thiophene ring-containing organic compound is at least one compound selected from the group consisting of dibenzothiophene and alkyldibenzothiophene compounds.

9. A method of regenerating a desulfurization agent, comprising heat treating the desulfurization agent after the desulfurization treatment carried out using the method in accordance with paragraph 5, to remove an organic compound containing sulfur adsorbed on the desulfurization agent.

10. The method of desulfurization, including bringing the desulfurization agent, which is subjected to a regeneration treatment using the method in accordance with paragraph 9, in contact with a liquid containing an organic compound containing sulfur, using the method in accordance with paragraph 5.

The desulfurization agent of the present invention, its production method and method of its use are described in detail below.

Desulfurization agent

The desulfurization agent of the present invention has a structure in which gold nanoparticles having an average particle size of 50 nm or less are deposited on a metal oxide.

The metal oxide coated with gold nanoparticles described above is known to exhibit high activity as a catalyst for various chemical reactions, including oxidative removal of carbon monoxide or formaldehyde; lower NOx levels in hydrocarbon exhausts; a methanol synthesis reaction by hydrogenation of carbon monoxide or carbon dioxide; a water vapor conversion reaction in which carbon dioxide and hydrogen are generated from carbon monoxide and water; a reaction for the synthesis of propylene oxide by selective oxidation of propylene; etc. However, the effect of selective adsorption of metal oxide on sulfur compounds in the liquid phase is unknown.

According to the present invention, it has now been found that a material having the structure described above in which nanosized fine gold particles are deposited on a metal oxide has the effect of selective adsorption on various organic compounds containing sulfur in the liquid phase, and that such a material is effective in as a desulfurization agent.

The desulfurization agent of the present invention preferably has a structure in which nanosized gold particles are uniformly deposited on the surface of a metal oxide-based support. Gold particles deposited on a metal oxide are in nanoscale, that is, in ultrafine state. Accordingly, the surface area of gold required for adsorption is very large and allows to demonstrate excellent adsorption performance. In addition, the active combustion center necessary for regeneration of the adsorbent after desulfurization is believed to be formed at the binding boundary between gold and metal oxide, and thus the particle size is preferably as small as possible to create as many binding sites , as much as possible. Specifically, the average particle size for gold particles can range from a size of a gold atom to about 50 nm, preferably about 1 to 10 nm. Note that in the present description, the average particle size for gold particles is the average of the values measured using the method using a transmission electron microscope, or is the size of the gold crystallites calculated using the Scherrer equation from the data of x-ray diffraction analysis. These values, as confirmed, are essentially the same in the case of a catalyst based on gold nanoparticles.

The oxides that contain the following elemental metals can be used, for example, as metal oxide coated with gold particles: beryllium, magnesium, aluminum, silicon, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, cadmium, indium, tin, barium, lanthanoid elements and the like. These metal oxides may be single metal oxides in which only one of the above elemental metals is contained; or mixed oxides in which two or more of the above elemental metals are contained. Among these metal oxides, a metal oxide containing one or more elemental metals selected from titanium, manganese, iron, cobalt, nickel, zinc, zirconium, lanthanum, cerium and the like is particularly preferred. The single metal oxides and mixed oxides described above can also be mixed for use if necessary. Note that when any element of beryllium, magnesium, calcium, strontium and barium, which are elements of Group 2 of the periodic system, is used, the desulfurization agent may also contain hydroxide, basic carbonate and the like, in addition to the corresponding oxide, depending on production method. In the present invention, an “oxide” on which gold is deposited in the form of nanoparticles may include hydroxide, basic carbonate and the like.

In the desulfurization agent of the present invention containing a metal oxide coated with gold nanoparticles, the gold content therein is not in any way limited as long as the desulfurization agent can be prepared so that the gold can be maintained in the state of the nanoparticles. For example, by appropriately selecting the metal oxide used as the carrier and the preparation method, a desulfurization agent having a gold content of about 0.1 to 60% by weight, based on the total weight of the gold nanoparticles and the metal oxide, can be obtained.

The form of the desulfurization agent of the present invention, that is, a metal oxide coated with gold nanoparticles, can be selected appropriately in accordance with the purpose of its use. For example, it can be used in powder form. It can also be used by forming it in granular form, in the form of tablets and the like. In addition, it can be used in the form of a product on a substrate by fixing metal oxide, with gold nanoparticles deposited on it, on a carrier element. The shape of the carrier element is not in any way limited insofar as the metal oxide coated with gold nanoparticles on its surface can be fixed on the carrier element. The carrier element may be in any shape, such as a planar shape, parallelepiped, fiber, mesh, sphere, honeycomb and the like. For example, when a carrier element is used in the form of honeycombs, a desulphurization agent prepared in the form of a powder can adhere to the surface of the honeycomb structure for use, or the oxide can be fixed on the surface of the honeycomb structure in advance, and gold nanoparticles can be directly applied to this surface using the following a deposition method, precipitation, or the like. The material of the support element is also not in any way limited insofar as it is stable under the conditions under which gold nanoparticles are deposited and under desulfurization conditions. For example, various ceramics may be used.

The specific surface area of the metal oxide in the state in which the gold nanoparticles are deposited on it is preferably from about 1 to 2000 m ² / g, more preferably from about 5 to 1000 m ² / g, as measured by the BET method. To obtain such an oxide coated with gold nanoparticles, a metal oxide having a sufficient specific surface area can be used in the range described above, for example, to deposit gold nanoparticles on it.

A method of manufacturing a desulfurization agent

The method of applying gold in the form of nanoscale particles to a metal oxide is not in any way limited. For example, the following known production methods may be used.

(a) Co-precipitation method (Japanese Unexamined Patent Application Publication No. 60-238148, and the like).

(b) The method of deposition, deposition (publication of the unexamined patent application of Japan No. 3-97623, and the like).

(c) Colloidal Mixing Method (Tsubota S. et al., Catal. Lett., 56 (1998), p. 131).

(d) Gas phase inoculation (Japanese Unexamined Patent Application Publication No. 9-122478).

(e) Liquid Phase Inoculation (Okumura M. et al., Chem. Lett., (2000), p. 396).

In the methods described above, water-soluble gold compounds (e.g., hydrochloric acid), compounds that evaporate when heated, such as a complex of gold acetylacetonate, and the like, can be used as a gold precursor to precipitate fine particles of gold in accordance with the method used.

For example, nitrate salts, sulfates, acetates, chlorides and the like of various metals can be used as starting materials for metal oxide in accordance with the deposition method used. Specifically, nitrate salts such as cerium nitrate, zirconium nitrate, and the like can be used; sulfates such as titanium sulfate and the like; and chlorides such as cerium chloride, titanium trichloride, titanium tetrachloride, and the like.

In the co-precipitation method (a), first, the oxide precursor and the gold precursor are simultaneously precipitated under alkaline conditions. Then, the thus obtained precipitate of a mixture of gold hydroxide and hydroxide of the oxide precursor is filtered, washed with water, dried and subjected to heat treatment, as described below, to obtain an oxide coated with gold nanoparticles.

In the methods for producing (b) to (e), the oxide precursor must be formed as an oxide or hydroxide prior to the deposition of gold. Commercially available oxide or hydroxide may be used from the outset. Its form is not in any way limited. A product in the form of powder, spheres, granules or honeycombs may be used. The oxide may optionally be an oxide having a uniform composition, and a product can also be used, for example, in which titanium oxide covers the surface of a ceramic honeycomb structure. The gold precursor is applied using methods (b) to (e) on the surface of an oxide or hydroxide as described above, followed by filtration, washing with water and drying, if necessary. Then, the product is subjected to heat treatment, thereby obtaining an oxide with gold nanoparticles deposited on it.

In the case of the co-precipitation method and the deposition-precipitation method, among the production methods described above, the addition of magnesium citrate during production is effective in reducing the particle size of gold, as described, for example, in Japanese Unexamined Patent Application Publications Nos. 5-325 and 6 -29137. This method is used especially effectively when a large amount of gold is applied.

In the known production methods described above, for the final conversion of gold to a metallic state, the heat treatment can be carried out in various atmospheres, for example, in an atmosphere containing oxygen, in an atmosphere of a reducing gas, in an atmosphere of an inert gas and the like. As an atmosphere containing oxygen, an air atmosphere or a mixed gas atmosphere in which oxygen is diluted with nitrogen, helium, argon, or the like can be used. As the reducing gas, for example, about 1-10% by volume of gaseous hydrogen, gaseous carbon monoxide, and the like diluted with gaseous nitrogen and the like can be used. As an inert gas, for example, nitrogen, helium, argon, and the like can be used.

The temperature of the heat treatment can be appropriately selected from the range of known conditions for producing metallic gold and usually, preferably, is in the range of from about room temperature to about 600 ° C. A range of from about 200 ° C to 400 ° C is more preferable to obtain stable and finely divided particles of gold. The heat treatment time may be, for example, from about 1 to 12 hours.

Desulfurization Treatment Facility

The desulfurization agent of the present invention can be used in a method for adsorbing and removing various organic compounds containing sulfur in a liquid phase. Examples of such sulfur-containing organic compounds include thiol (R-SH), sulfide (R-S-R), disulfide (R-S-S-R), tetrahydrothiophene, thiophene-based compounds and the like. The term “thiophene-based compounds” as used herein refers to a group of compounds having a thiophene ring. Examples thereof include thiophene, alkylthiophene, benzothiophene, alkylbenzothiophene, dibenzothiophene, alkyldibenzothiophene, dialkyldibenzothiophene and the like.

The desulfurization agent of the present invention is effectively used for adsorption desulfurization of an organic compound containing sulfur, in particular a compound based on thiophene remaining in liquid fuel. A thiophene-based compound, such as 4,6-dimethylbenzothiophene, in which the sulfur concentration cannot be reduced below 10 ppm. using a conventional method, it can be adsorbed and removed to such an extent that the sulfur concentration becomes lower than 10 ppm using the desulfurization agent of the present invention.

The type of liquid fuel to be processed is not limited in any way and can be any fuel of gasoline, kerosene, lighting oil, light gas oil, heavy oil and the like. The concentration of sulfur contained in the liquid fuel prior to processing is also not in any way limited; however, from the point of view of the fact that a large amount of a desulfurization agent will be required when liquid fuel having a high sulfur concentration is directly processed, the sulfur concentration is preferably lowered to 50 ppm in advance. or less, more preferably up to 10 ppm. or less, using a method such as hydrodesulfurization and the like.

Desulfurization Method

Using the desulfurization method that uses the desulfurization agent of the present invention, desulfurization can be carried out by bringing the liquid to be desulfurized, for example liquid fuel, into contact with the desulfurization agent and thereby adsorb the organic compound containing sulfur in the liquid. There are two common methods: boot technology and flow technology.

Using loading technology, for example, a method of adding a desulfurization agent to a container containing liquid fuel and mixing the mixture can be used. Although the adequate amount of desulfurization agent to be used varies depending on the type of desulfurization agent, the desulfurization agent, for example, is preferably used in the range of 1 to 500 g per liter of liquid fuel, and more preferably, used in the range of 10 to 100 g per liter of liquid fuel. The processing temperature is not in any way limited insofar as it is maintained within such limits where the fuel to be processed can maintain its liquid state. For example, processing may be carried out at room temperature. Pressure is also not limited in any way. Although the treatment can be carried out at elevated pressure, it can usually be carried out at atmospheric pressure.

After a certain period of time has elapsed after the addition of the desulfurization agent, the liquid and the desulfurization agent are separated, and a desulfurization agent and a liquid having a reduced amount of organic compounds containing sulfur can be obtained. Although the processing time cannot be determined in general terms, since it varies depending on the concentrations of sulfur compounds and the amount of desulfurization agent used, the treatment can be carried out, for example, in the range of about 1 hour to several days, until the desired desulfurization effect is obtained.

The separated desulfurization agent can be regenerated, for example, using the method described below, in which the desulfurization agent is dried and then heated in air, and reused.

In the case of flow-through technology, the liquid to be processed can pass at a constant flow rate through a tubular container in which the desulfurization agent is placed in the form of a layer. The volumetric hourly rate of the liquid phase (LHSV) in this case can be set, for example, in the range of about 0.01 to 100 hour ^-1 , preferably about 0.01 to 1 hour ^-1 . Conditions, such as temperature, pressure, and the like, for desulfurization are not in any way limited, insofar as they are within the limits where the fuel is a liquid, as is the case with loading technology. When there is no external heat source, processing can be carried out at room temperature. When liquid fuel is supplied in a preheated state, adsorption desulfurization can be carried out at a preheating temperature.

Regeneration Method

After the liquid is desulfurized by adsorption of an organic sulfur-containing compound in a liquid according to the method described above, the desulfurization agent is heat treated, thereby removing the organic sulfur-containing compound adsorbed on the desulfurization agent, and allowing the regeneration and reuse of the desulfurization agent . Note that with respect to the heat treatment of the desulfurization agent, the desulfurization agent is preferably heated after washing with a solvent or the like, and dried, if necessary.

Heat treatment can be carried out in various atmospheres, such as inert gas, diluted oxygen, air, water vapor, diluted hydrogen, and the like.

The metal oxide coated with gold nanoparticles, which constitutes the desulfurization agent of the present invention, is known to have catalytic activity for any of the following reactions: the reaction between O ₂ and a hydrocarbon such as methane, propane and the like (combustion reaction); a reaction between H ₂ O and a carbon compound such as CO and the like (conversion reaction); and a reaction between H ₂ and a carbon compound such as CO, CO ₂ , aldehyde and the like (hydrogenation reaction). Accordingly, performing heat treatment in an atmosphere containing any gas of O ₂ , H ₂ O, and H ₂ allows efficient removal of the adsorbed organic compound containing sulfur by using a reaction such as a catalytic reaction between these molecules and an organic compound containing sulfur, which is adsorbed on the surface of a desulfurization agent, or a combustion reaction of an organic compound containing sulfur.

The concentration range of O ₂ , H ₂ O, H ₂ and the like in the atmosphere is not limited in any way; however, especially when H _{2 is} contained, the concentration must be controlled so that no explosive composition forms. Relative to pressure conditions, normal pressure can be used in the event of a combustion reaction. However, in the case of a hydrogenation reaction or the like, applying a pressure of 10 MPa or less can favorably accelerate the reaction. The heating temperature may be selected from a range of from about 50 ° C to 500 ° C, preferably from about 100 ° C to 400 ° C, more preferably from about 150 ° C to 400 ° C. When the heating temperature is too high, gold nanoparticles easily aggregate, causing an unfavorable degradation of adsorption performance after regeneration.

[Advantageous Effects of the Invention]

The desulfurization agent of the present invention has a selective adsorption effect on organic compounds containing sulfur in the liquid phase. In particular, the concentration of sulfur compounds in liquid fuels may drop to levels that cannot be achieved using conventional technologies.

The desulfurization agent of the present invention can be used in various applications by using superior performance for adsorption removal of an organic sulfur-containing compound as described above. For example, after lowering the concentration of the sulfur-containing organic compound by using the conventional hydrodesulfurization method, the sulfur-containing organic compound is adsorbed and removed using an adsorption column filled with the desulfurization agent of the present invention. In this way, the sulfur concentration in the liquid fuel can drop to 10 ppm. or less. In addition, the sulfur concentration may also decrease to 0.1 ppm. or less, that is, to the concentration desired for the fuel for the fuel cell.

In addition, as an example of how to use the present invention, in the same manner as described in NPL 1 described above, a column filled with the desulfurization agent of the present invention may be installed between the fuel tank and the gas pump at a gas station in order to desulfurization, while at the same time supplying fuel to the vehicle.

Brief Description of the Drawings

[Fig. 1] Fig. 1 is a graph showing the time course of a change in the concentration of dibenzothiophene in solution in Study Example 1.

[Figure 2] Figure 2 is a graph showing the concentration of sulfur (converted from the analytical value of the concentration of dibenzothiophene) that remains in the solution after reaching adsorption equilibrium, and the amount of dibenzothiophene adsorbed on the desulfurization agent when the amount of agent used for desulfurization, varies in Study Example 2.

[Fig. 3] Fig. 3 is a graph showing the adsorption saturation value of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (DMDBT) and naphthalene (NA) obtained by the first adsorption step (before regeneration) and the second adsorption step (after regeneration) using each sample in Study Example 3.

[Fig. 4] Fig. 4 is a diagram showing a saturation amount of dibenzothiophene adsorption (DBT) obtained by each adsorption operation when adsorption and regeneration are alternated in Example 4.

[Fig. 5] Fig. 5 is a graph showing a relationship between a heating temperature during a regeneration treatment and a saturation amount of dibenzothiophene (DBT) adsorption on a sample after regeneration, in Test Example 5.

[Fig. 6] Fig. 6 is a graph depicting the amount of CO ₂ generated during an increase in temperature as a function of temperature when the thermal regeneration treatment is carried out at 350 ° C., in Test Example 5.

[Fig. 7] Fig. 7 is a graph showing the saturated adsorption amount of 4,6-dimethyldibenzothiophene (DMDBT) in each sample from test solution E, compared with the adsorption value of DBT, DMDBT and NA from test solutions A and C.

DESCRIPTION OF EMBODIMENTS

The present invention is described in more detail with reference to examples below.

Example 1

(1) Obtaining a desulfurization agent

Desulfurization Agent 1: Gold / Ceria (Au / CeO ₂ )

An aqueous solution (1000 ml) of hydrochloric acid [HAuCl ₄ · 4H ₂ O] (5 mmol / L) was heated to 70 ° C and KOH was added dropwise thereto to adjust the pH to 7. Cerium oxide powder (7.7 g) was added to it, and then a solution (370 ml) of magnesium citrate (10 mmol / l) is added to it. The mixture was stirred for 1 hour, filtered, washed with water and dried, and the powder thus obtained was calcined for 4 hours in air at 400 ° C, thereby obtaining a desulfurization agent 1 (Au / CeO ₂ ) having a structure in which nanoparticles gold having an average particle size of 5.5 nm, deposited on the surface of cerium oxide (the amount of deposited Au: 11.3% wt.). Note that the average particle size for the gold nanoparticles in the Examples is the size of gold crystallites calculated using the Scherrer equation from the data of the measurement of x-ray diffraction by powders.

Desulfurization Agent 2: Gold / Ceria (Au / CeO ₂ )

A desulfurization agent 2 (Au / CeO ₂ ) having a structure in which gold nanoparticles having an average particle size of 4.9 nm are deposited on the surface of cerium oxide (amount of deposited Au: 1.0% by weight) is prepared using the same the production method, as for the desulfurization agent 1, except that the used amount of hydrochloric acid is reduced and magnesium citrate is not added.

Desulfurization Agent 3: Gold / Zinc Oxide (Au / ZnO)

An aqueous solution in which sodium carbonate Na ₂ CO ₃ (8 g) is dissolved in water (200 ml) is heated to 70 ° C. An aqueous solution in which zinc nitrate (14.2 g) and hydrochloric acid (1.1 g) are dissolved in water (200 ml) is added to it at 70 ° C and a precipitate forms. After stirring for 1 hour, filtering, washing with water and drying are carried out. The powder thus obtained was calcined for 4 hours in air at 400 ° C., thereby obtaining a desulfurization agent 3 (Au / ZnO) having a structure in which gold nanoparticles having an average particle size of 5.8 nm were deposited on a surface of zinc oxide (Amount of Au applied: 10.0% by weight).

Desulfurization Agent 4: Gold / Titanium Oxide (Au / TiO ₂ )

An aqueous solution (1000 ml) of hydrochloric acid (5 mmol / L) was heated to 70 ° C and KOH was added dropwise thereto to adjust the pH to 7. Titanium oxide powder (3.6 g) was added to it, and then added to it a solution (400 ml) of magnesium citrate (10 mmol / l). The mixture was stirred for 1 hour, filtered, washed with water and dried, and the powder thus obtained was calcined for 4 hours in air at 400 ° C., thereby obtaining a desulfurization agent 4 (Au / TiO ₂ ) having a structure in which nanoparticles gold having an average particle size of 4.0 nm, deposited on the surface of titanium oxide (amount of deposited Au: 21.5% wt.).

Desulfurization Comparative Agent 1: Cerium Oxide (CeO ₂ )

The cerium oxide powder used to produce desulfurization agents 1 and 2 is used as is.

Desulfurization Comparative Agent 2: Platinum / Cerium Oxide (Pt / CeO ₂ )

An aqueous solution (500 ml) of platinum hydrochloric acid [H ₂ PtC ₆ · 6H ₂ O] (2 mmol / L) was heated and KOH was added dropwise to adjust the pH to 7. Cerium oxide powder (6.5 g) was added to it . The mixture was stirred for 1 hour, filtered, washed with water and dried, and the powder thus obtained was calcined for 4 hours in air at 400 ° C. Then, the temperature was raised to 350 ° C. in a mixed gas stream from H ₂ (3%) + He (residue) to reduce Pt, thereby obtaining a desulfurization comparative agent 2 (Pt / CeO ₂ ), in which platinum having an average particle size 2.0 nm or less, deposited on the surface of cerium oxide (amount of applied Pt: 3.0% by weight).

Desulfurization Comparative Agent 3: Y-type zeolite ion exchanged with cerium (Ce-Y)

Y-type zeolite powder (0.75 g) was added to an aqueous solution (30 ml) of cerium nitrate [Ce (NO ₃ ) ₃ · 6H ₂ O] (0.2 mol / L) and the mixture was stirred by shaking for 3 days . The mixture was filtered, washed with water and dried, and the powder thus obtained was calcined for 2 hours in air at 400 ° C, thereby obtaining a desulfurization comparative agent 3 containing Y-type zeolite subjected to ion exchange with cerium (Ce-Y).

Desulfurization Comparative Agent 4: Copper / Zinc Oxide (Cu / ZnO)

An aqueous solution in which sodium carbonate Na ₂ CO ₃ (7.6 g) is dissolved in water (200 ml) is heated to 70 ° C. An aqueous solution containing zinc nitrate (12.5 g) and copper nitrate (4.3 g) was dissolved in water (300 ml), added to it at 70 ° C, and a precipitate formed. After stirring for 1 hour, filtering, washing with water and drying are carried out. The powder thus obtained was calcined for 4 hours in air at 400 ° C. Then, the temperature was raised to 400 ° C. in a mixed gas stream from H ₂ (3%) + He (residue) to reduce Cu, thereby obtaining a desulfurization comparative agent 4 (Cu / ZnO) in which copper having an average particle size of 3 , 3 nm, deposited on the surface of zinc oxide (amount of deposited Cu: 25.1% by weight).

(2) Desulfurization Study

The following test solutions are prepared for A, B, C, D, and E.

Test Solution A

Using n-decane (manufactured by Kishida Chemical Co., Ltd., special quality) as a solvent, a solution is prepared containing the following components: dibenzothiophene (39.9 mg / l) (manufactured by Kanto Chemical Co., Inc., special quality) as an organic sulfur compound and n-tetradecane (39.5 mg / L) (manufactured by Kishida Chemical Co., Ltd., special quality) as an internal standard for solution analysis. The sulfur concentration in this solution is 9.5 ppm.

Test Solution B

Using n-decane as a solvent, as in test solution A, a solution is prepared containing dibenzothiophene (51.2 mg / L) as an organic sulfur compound. The sulfur concentration in this solution corresponds to 12.2 ppm.

Test solution C

Using n-decane (manufactured by Kishida Chemical Co., Ltd., special quality) as a solvent, a solution is prepared containing the following components: dibenzothiophene (22.7 mg / l) (manufactured by Kanto Chemical Co., Inc., special quality) and 4,6-dimethyldibenzothiophene (23.1 mg / L) (manufactured by Wako Pure Chemical Industries, Ltd., special quality) as organic sulfur compounds, naphthalene (22.1 mg / L) (manufactured by Wako Pure Chemical Industries, Ltd ., special quality) as a sulfur-free aromatic organic compound and n-tetradecane (26.5 mg / l) (manufactured by Kishida Chemical Co., Ltd., special quality) as an internal standard for solution analysis. The total sulfur concentration in this solution is 10.2 ppm, with dibenzothiophene being 5.4 ppm. and 4,6-dimethyldibenzothiophene is 4.8 ppm.

Test Solution D

Using n-decane as a solvent, as in test solution A, a solution is prepared containing dibenzothiophene (43.2 mg / l) as an organic sulfur compound and n-tetradecane (69.3 mg / l) as an internal standard for analysis solution. The sulfur concentration in this solution corresponds to 10.3 ppm.

Test solution E

Using n-decane (manufactured by Kishida Chemical Co., Ltd., special quality) as a solvent, a solution is prepared containing the following components: 4,6-dimethyldibenzothiophene (46.7 mg / l) (manufactured by Wako Pure Chemical Industries, Ltd. , special quality) and n-tetradecane (45.3 mg / L) (manufactured by Kishida Chemical Co., Ltd., special quality) as an internal standard for solution analysis. The sulfur concentration in this solution corresponds to 9.7 ppm.

Methods for the study of adsorption and regeneration

Study Example 1

Samples of powders of desulfurization agents 1 and 2 and comparative desulfurization agent 1 prepared using the method described above are heated in air at 300 ° C for 30 minutes to remove adsorbed water, and then cooled to room temperature in a desiccator containing silica gel. 100 mg of each sample is weighed and placed in separate bottles with caps on the thread, and test solution A (5 ml) is added to each bottle, which is then closed with a cap. This point in time is considered the beginning of adsorption. The solution was stirred using a stirrer at room temperature. Although the temperature of the solution is raised to 60 ° C, at one point in time, between 8.5 hours and 24 hours in desulfurization agent 1, and at one point in time, between 27 hours and 47 hours in desulfurization agent 2 and in comparative desulfurization agent 1, in a separate experiment, it is confirmed that this almost does not affect the adsorption under experimental conditions of the present research examples. After the start of adsorption, approximately 0.1 ml of the solution is removed using a pipette every few hours, and the composition of the solution is analyzed using FID-GC (gas phase chromatography with flame ionization detector). Figure 1 shows the time course of changes in the concentration of dibenzothiophene in solution.

Figure 1 shows that desulfurization agents 1 and 2, in which gold nanoparticles are supported on cerium oxide, adsorb a greater amount of dibenzothiophene, compared with a comparative desulfurization agent 1 containing only cerium oxide, and in particular desulfurization agent 1, in which the amount of gold deposited is large (11.3% wt.), adsorb a very large amount of dibenzothiophene. In addition, there is a phenomenon in which the adsorption value becomes stable after at least 24 hours pass in the case of desulfurization agents 1 and 2, while the adsorption value decreases after 5 hours pass in the case of a desulfurization comparative agent 1 containing only cerium oxide.

The results described above clearly show that the use of desulfurization agents 1 and 2, in which gold nanoparticles are supported on cerium oxide, allows efficient adsorption desulfurization of dibenzothiophene, for which the sulfur concentration in the decane solution is approximately 10 ppm.

Study Example 2

A sample of the powder of desulfurization agent 1 prepared using the method described above is heated in air at 300 ° C for 30 minutes to remove adsorbed water, and then cooled to room temperature in a desiccator containing silica gel. Then, 26 mg, 51 mg, 101 mg, 200 mg and 300 mg of this sample are weighed and placed in five bottles with lids on the thread, separately. Test solution B (5 ml) is added to each bottle with a cap on the thread, which is then closed with a cap. This point in time is considered the beginning of adsorption. The solution was stirred using a stirrer at room temperature. 74 hours or later after the start of adsorption (the achievement of adsorption equilibrium is confirmed), the solution is removed using a pipette and analyzed. A known amount of 2,8-dimethyldibenzothiophene (manufactured by Tokyo Chemical Industry Co., Ltd.) is added as an internal standard to each test solution and the composition is analyzed using FPD-GC.

Figure 2 is a graph showing the relationship between the mass of the desulfurization agent used and the concentration of sulfur remaining in the solution of this study example after adsorption and the amount of dibenzothiophene (DBT) adsorbed using the desulfurization agent. Note that the sulfur concentration in the test solution shown in FIG. 2 is obtained by converting the DBT concentration to the sulfur concentration.

Figure 2 clearly shows that the total amount of adsorbed dibenzothiophene (DBT) increases and the amount of remaining DBT in solution decreases when the amount of desulfurization agent used increases. In particular, when 300 mg of a desulfurization agent is used, 1.37 μmol of DBT is adsorbed, which is close to the initial amount of DBT (1.38 μmol) in the test solution (5 ml), and the sulfur concentration, which was 12.2 million before adsorption. d., drops to 0.1 ppm.

Study Example 3

Using desulfurization agents 1, 3, and 4 and comparative desulfurization agents 2-4 prepared using the method described above, adsorption and regeneration experiments are carried out using procedures (1) to (3) described below.

(1) First adsorption

Each desulfurization agent is heated in air at 300 ° C. for 30 minutes to remove adsorbed water, and then cooled to room temperature in a desiccator containing silica gel. 100 mg of each desulfurization agent is weighed and placed in separate bottles with caps on the thread and test solution C (5 ml) is added to each bottle, which is then closed with a cap. This point in time is considered the beginning of adsorption. The solution was stirred using a stirrer at room temperature. When at least 24 hours have passed and adsorption equilibrium is reached, approximately 0.1 ml of the solution is removed using a pipette and the composition of the solution is analyzed using FID-GC.

(2) Regeneration

After performing an adsorption experiment using the method described above, each desulfurization agent is separated by filtration, washed with hexane and dried at room temperature. After drying, the powder of the desulfurization agent is placed in a quartz reaction tube and fixed with quartz wool placed in a tube on both sides of the agent. While the mixed gas from He (80%) + O ₂ (20%) passed through the reaction tube at a flow rate of 100 ml / min, the temperature was raised to 350 ° C at 10 ° C / min, and then it was maintained at 350 ° C within 10 minutes With this operation, the components adsorbed on the surface of each desulfurization agent are removed by thermal desorption or catalytic combustion, and each desulfurization agent is regenerated. The progress of this process is monitored by monitoring the gas leaving the reaction tube.

(3) Second adsorption

After the regeneration of each desulfurization agent using the method described above, the powder of the desulfurization agent, which is brought back to room temperature, is weighed and placed in separate bottles with lids on the thread. Since there is a decrease in the amount of each desulfurization agent recovered after the regeneration treatment, the test solution C is added to it in a proportion of 5 ml per 100 mg of powder of desulfurization agents, so that the ratio of the test solution to the desulfurization agent is the same as in the adsorption study in (1 ) described above, and each bottle with a cap on the thread is closed with a cap. When at least 24 hours have passed and adsorption equilibrium is reached, approximately 0.1 ml of the solution is removed using a pipette and the composition of the solution is analyzed using FID-GC.

The amounts of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (DMDBT) and naphthalene (NA) adsorbed per gram of desulfurization agent powder are calculated from the solution composition analysis. Figure 3 shows the results.

Figure 3 shows that the use of desulfurization agents 1, 3 and 4, in which gold nanoparticles deposited on a metal oxide, allows selective adsorption of dibenzothiophenes (DBT + DMDBT) and, in particular, very selective adsorption of DBT. Relative to desulfurization comparative agents 2 containing Y-type zeolite ion-exchanged with cerium (Ce-Y), although the total amount of first adsorption on it was higher compared to desulfurization agents 1, 3 and 4, it adsorbs essentially equimolar amounts of DBT, DMDBT, and NA, showing a lack of selective adsorption of organic sulfur compounds.

In addition, even in the second adsorption study, desulfurization agents 1, 3, and 4 are able to adsorb dibenzothiophenes (DBT + DMDBT) in an amount that is at least 70% of the amount adsorbed in the first adsorption study, clearly demonstrating a particularly high the proportion of adsorption after regeneration, compared with comparative desulfurization agents 2 and 3.

With respect to Cu / ZnO (desulfurization comparative agent 4), which is effective as an adsorbent for hydrogen sulfide, the adsorbent contains a large amount of Cu, which, like Au, is an element of group IB, the amount of adsorbed dibenzothiophenes is small, it shows poor working characteristics as adsorbents for organic compounds containing sulfur.

Study Example 4

The adsorption of dibenzothiophene (DBT) and the regeneration of the desulfurization agent are repeated tested using methods (1) to (3) described below. Note that this study is carried out by modifying the treatment method during regeneration to prevent a decrease in the amount of desulfurization agent recovered after regeneration.

(1) First adsorption

100 mg of desulfurization agent 1 is weighed and placed in a 20 ml pear shaped flask (made of heat-resistant glass). The flask was placed in an electric oven, heated at 350 ° C in air for 30 minutes to remove adsorbed water, and then cooled to room temperature in a desiccator containing silica gel. Immediately after the flask is removed from the desiccator, the flask is sealed with a cap from Teflon (registered trade name) and its mass is measured to determine the amount of desulfurization agent after thermal dehydration. Test solution D (5 ml) was added to it and the flask was sealed with a cap from Teflon (registered trade name). This point in time is considered the beginning of adsorption. The solution was stirred using a stirrer at room temperature. When at least 24 hours have passed and adsorption equilibrium is reached, stirring is stopped and the flask is allowed to stand still to allow sedimentation of the powder of desulfurization agents. The supernatant solution was removed using a pipette and the composition of the solution was analyzed using FID-GC.

(2) Regeneration

After performing an adsorption experiment using the above method, the flask is allowed to stand still for sedimentation of the powder of desulfurization agents. The flask was carefully tilted to drain the remaining supernatant solution without flowing out the desulfurization agent powder, and approximately 5 ml of hexane was added to it. The operation of adding hexane and draining the supernatant solution is repeated three times altogether. Then, nitrogen gas was purged through the flask to allow the evaporation of hexane. The flask was placed in an electric oven and heated at 350 ° C. in air for 30 minutes to thermally regenerate the desulfurization agent. After heating, the flask is cooled to room temperature in a desiccator containing silica gel. Immediately after removing the flask from the desiccator, the flask is sealed with a cap from Teflon (registered trade name) and its weight is measured to determine the amount of desulfurization agent after regeneration. As described above, the regeneration is carried out without removing the adsorbent powder from the flask. As a result, even after the fourth regeneration, at least 99% wt. the original adsorbent used.

(3) Second and subsequent adsorption and regeneration

After regeneration of the desulfurization agent using the method described above, the test solution D is added to the flask in a proportion of 5 ml per 100 mg of powder of desulfurization agents placed in the flask, and then the flask is sealed with a cap from Teflon (registered trade name) (beginning of the second adsorption ) The solution was stirred using a stirrer at room temperature. When at least 24 hours have passed and adsorption equilibrium is reached, stirring is stopped and the flask is allowed to stand still to allow sedimentation of the desulfurization agent powder. The supernatant solution was removed using a pipette and the solution composition was analyzed using GC. After this, the regeneration and adsorption operations are repeated in the same manner as described above. When the regeneration is repeated, the adsorbent powder adheres to the wall of the upper part of the flask, which leads to poor contact with the solution. Thus, for the fourth and subsequent adsorption operations, after the adsorption solution is placed in the flask and the flask is sealed with a cap from Teflon (registered trade name), the flask is immersed in water in an ultrasonic cleaning device that lasts for 10 seconds up to several minutes, at the beginning of adsorption, to improve dispersion of the adsorbent powder, and at the same time, contact with the solution is restored.

The amount of adsorbed dibenzothiophene (DBT) per 1 g of powder of desulfurization agents is calculated from the analysis results of the solution composition at the end of the adsorption each time. 4 shows the results.

Figure 4 clearly shows that there is no significant decrease in the amount of adsorption, even when adsorption and regeneration are repeated. With respect to a small decrease in the values of the second and third adsorption, the contact between the adsorbent and the solution is believed to be slightly deteriorating, since the first or third adsorption is carried out without the operation of using an ultrasonic cleaning device at the beginning of adsorption to improve the dispersibility of the adsorbent. At the fourth and fifth adsorption, the adsorption value becomes stable, and it remains at 95% or more of the value of the first adsorption.

The results described above clearly show that the desulfurization agent of the present invention, in which gold nanoparticles are supported on a metal oxide, is superior in performance to the selective adsorption of organic compounds containing sulfur, in particular dibenzothiophene compounds, and that the desulfurization agent can exhibit sufficient adsorption performance after processing regeneration by heating and can be reused as a desulfurization agent.

Study Example 5

Using a desulfurization agent 1 prepared using the method described above, adsorption and regeneration are carried out using procedures (1) to (3) described below to study the effect of heating temperature during regeneration.

(1) First adsorption

100 mg of desulfurization agent 1 is weighed and placed in 7 separate bottles with lids on the thread. Each bottle is heated in air at 350 ° C for 30 minutes to remove adsorbed water, then cooled to room temperature in a desiccator containing silica gel and left to stand overnight to allow moisture absorption in the desiccator, where the relative humidity is adjusted to 85% s using a saturated solution of potassium chloride. Note that, since the objective of Example 5 is to investigate the effect of heating temperature during regeneration on the amount of dibenzothiophene (DBT) adsorbed, the conditions are standardized so that each sample adsorbs moisture under specific conditions before DBT adsorption starts, to eliminate the effect of differences in the amount of remaining moisture for DBT adsorption.

Test solution A (5 ml) is added to each bottle with a cap on the thread, which is then closed with a cap. This point in time is considered the beginning of adsorption. The solution was stirred at room temperature using a stirrer. When at least 24 hours have passed and adsorption equilibrium is reached, approximately 0.1 ml of the solution is removed using a pipette and the composition of the solution is analyzed using FID-GC.

(2) Regeneration

After performing an adsorption experiment using the above method, the solution remaining in each bottle with a cap on the thread is poured using the same operation as in Example 4, and the inside of the bottle with a cap on the thread is washed with hexane and dried. One bottle with a cap on the thread is left to stand overnight in a desiccator containing silica gel at room temperature (25 ° C). Five bottles with lids on the thread individually placed in an electric furnace, with temperatures set at 100, 150, 200, 250 and 300 ° C, respectively, and heated in air for 30 minutes. With respect to one remaining bottle with a cap on the thread, the desulfurization agent powder is removed from it, placed in a reaction tube made of quartz and fixed with quartz wool placed in a tube on both sides of the agent. During the passage of the mixed gas from He (80%) + O ₂ (20%) through the reaction tube at a flow rate of 100 ml / min, the temperature is raised to 350 ° C at a speed of 10 ° C / min, and then maintained at 350 ° C within 30 minutes The concentration of CO ₂ generated during the temperature rise is measured using a mass spectrometer and Photoacoustic Multi-gas Monitor (manufactured by INNOVA).

The desulfurization agent is heat treated at 25, 100, 150, 200, 250, 300 ° C or 350 ° C as described above, then cooled to room temperature in a desiccator containing silica gel and allowed to stand overnight to allow absorption humidity in the desiccator, where the relative humidity is adjusted to 85% using a saturated solution of potassium chloride.

(3) Second adsorption

To the desulfurization agent, which adsorbs moisture after the thermal regeneration treatment, at each temperature, using the above method, add test solution A in a proportion of 5 ml per 100 mg of desulfurization agent powder and each bottle is closed with a lid. When at least 24 hours have passed and adsorption equilibrium is reached, approximately 0.1 ml of the solution is removed using a pipette and the composition of the solution is analyzed using FID-GC.

The amount of adsorbed dibenzothiophene (DBT) per 1 g of desulfurization agent powder is calculated from the analysis results of the solution composition. At the first adsorption, all samples in 7 bottles with caps on the thread, subjected to adsorption under the same conditions, absorb DBT in the amount of 3.3 ± 0.1 μmol / g · of catalyst. With respect to the amount of DBT adsorbed by the second adsorption after regeneration by heat treatment at each temperature, the relationship between the heat treatment temperature and the amount of adsorbed DBT is shown in FIG. From figure 5 it is clear that with respect to the desulfurization agent 1 (Au / CeO ₂ ), when the heat treatment temperature is 100 ° C or lower, the value of the second adsorption is significantly reduced compared to the first adsorption, showing that the heat treatment temperature is insufficient . Further, when the heat treatment temperature is 200 ° C or higher, the second adsorption value is substantially the same as for the first adsorption, indicating that the desulfurization agent is completely regenerated.

6 is a graph depicting the amount of CO ₂ produced during heating as a function of temperature when heated to 350 ° C. Peaks in CO ₂ concentration are observed at two temperatures: 115 and 225 ° C. Among them, a peak on the low temperature side is also observed for the Au / CeO ₂ sample, which does not adsorb DBT. In this case, likely to adsorb CO ₂ from the air. A peak from the high temperature side is observed only after DBT adsorption. In this case, it is likely that the adsorbed DBT burns out on the catalytic surface and is converted to CO ₂ . The amount of CO ₂ that corresponds to the shaded part in FIG. 6 is 37.2 μmol / g · of catalyst. This remarkably corresponds to the amount of CO ₂ (39.6 μmol / g · catalyst), determined on the basis of the assumption that DBT (3.3 μmol / g · catalyst) adsorbed upon the first adsorption completely burns to CO ₂ .

Study Example 6

By using test solution E (a solution that contains only 4,6-dimethyldibenzothiophene as the dibenzothiophene compound), desulfurization agents 1, 3, and 4 prepared using the above method are subjected to an adsorption experiment using the procedures described below.

Each desulfurization agent is heated in air at 350 ° C. for 30 minutes to remove adsorbed water, and then cooled to room temperature in a desiccator containing silica gel. 100 mg of each desulfurization agent is weighed and placed in separate bottles with caps on the thread and test solution E (5 ml) is added to each bottle, which is then closed with a cap. This point in time is considered the beginning of adsorption. The solution was stirred using a stirrer at room temperature. When at least 24 hours have passed and adsorption equilibrium is reached, approximately 0.1 ml of the solution is removed using a pipette and the composition of the solution is analyzed using FID-GC.

The amount of 4,6-dimethyldibenzothiophene (DMDBT) adsorbed per gram of desulfurization agent powder is calculated from the analysis of the solution composition. 7 shows the results. 7 also shows the results of an adsorption study obtained from Example Study 1 and Example Study 3, using test solution A (a solution that contains only DBT) and test solution C (a mixed solution containing DBT, DMDBT and NA), respectively. Note that the compositions of the test solutions A, C, and E are shown in Table 1 below.

Table 1 The concentration of each component (mg / l) Test solution E Test solution C Test Solution A 4,6-dimethylbenzothiophene (DMDBT) 46.7 23.1 Dibenzothiophene (DBT) 22.7 39.9 Naphthalene (NA) 22.1 N-tetradecane (internal standard for GC (gas chromatographic) analyzes) 45.3 26.5 39.5 Dean Solvent Solvent Solvent

In accordance with the results shown in FIG. 7, the results of an adsorption study using test solution C containing DBT, DMDBT and NA show that the amount of adsorbed DBT is higher than the amount of adsorbed DMDBT for all desulfurization agents 1, 3 and 4 This is probably due to the fact that DBT and DMDBT are competitively adsorbed on the adsorption center, and DBT, which does not contain methyl groups and has low steric hindrance, is adsorbed more selectively.

On the other hand, the amount of adsorbed DMDBT that is obtained from an adsorption study using test solution E, which is a solution containing only DMDBT, is significantly higher than the amount of DMDBT adsorbed from test solution C, which is a mixed solution. With respect to desulfurization agent 1 (Au / CeO ₂ ), a comparison between the amount of DMDBT adsorbed from a solution containing only DMDBT (test solution E) and the amount of DBT adsorbed from a solution containing only DBT (test solution A) shows that the amount of adsorbed DMDBT corresponds to approximately 97% of the amount of adsorbed DBT. This confirms the fact that the adsorbent of the present invention exhibits excellent DMDBT adsorption performance.

With respect to the sulfur-free fuel that is currently supplied, 4,6-dimethyldibenzothiophene, which is extremely difficult to remove using modern technology, makes up a relatively large proportion of the dibenzothiophene compounds remaining in the fuel. The results shown in FIG. 7 show that the desulfurization agent of the present invention has properties suitable for removing small amounts of the remaining 4,6-dimethyldibenzothiophene.

Claims (10)

1. A desulfurization agent for liquid phase adsorption desulfurization containing a metal oxide coated with gold nanoparticles having an average particle size of 50 nm or less. 2. The desulfurization agent according to claim 1, which has a specific surface area
1 m ² / g or more. 3. A desulfurization agent for liquid-phase adsorption desulfurization, where the metal oxide coated with gold nanoparticles according to claim 1 is fixed on the carrier element. 4. The desulfurization agent according to claim 1, in which the object of processing is a liquid fuel containing an organic compound containing sulfur. 5. The method of desulfurization, comprising bringing the desulfurization agent according to claim 1 into contact with a liquid containing an organic compound containing sulfur. 6. The desulfurization method according to claim 5, in which the object of processing is a liquid fuel containing an organic compound containing sulfur. 7. The desulfurization method according to claim 6, in which the liquid fuel serving as an object of processing contains an organic compound containing a thiophene ring. 8. The desulfurization process according to claim 7, wherein the organic compound containing a thiophene ring is at least one compound selected from the group consisting of compounds based on dibenzothiophene and alkyldibenzothiophene. 9. A method for regenerating a desulfurization agent, comprising heat treating the desulfurization agent after performing the desulfurization treatment, which is carried out using the method according to claim 5, to remove an organic compound containing sulfur adsorbed on the desulfurization agent. 10. The method of desulfurization, including bringing the desulfurization agent, which is subjected to processing and regeneration using the method according to claim 9, in contact with a liquid containing an organic compound containing sulfur, using the method according to claim 5.

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