Desulfurizing agent

Abstract

A desulfurizing agent according to the present disclosure is a desulfurizing agent for removing a sulfur compound from a raw material gas containing the sulfur compound, the desulfurizing agent containing a metal-organic structure containing copper ions, trimesic acid, and a benzoic acid compound, the benzoic acid compound is a compound obtained by substituting a hydrogen atom, which is meta-or para-position relative to a carboxyl group, of benzoic acid with a substituent, and the electron donating property of the benzoic acid compound is higher than that of benzoic acid.

Description

Technical Field

[0001] The present disclosure relates to a desulfurizing agent. Background Art

[0002] Patent Document 1 discloses a technique of bringing a metal organic structure composed of copper ions and trimesic acid into contact with a fuel gas (raw gas) containing a sulfide compound (sulfur compound) to remove the sulfide compound (sulfur compound) from the fuel gas (raw gas).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2017 / 150019 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a desulfurizing agent that can reduce the amount of the desulfurizing agent filled in a desulfurizer and achieve miniaturization of the desulfurizer.

[0008] Solutions for solving problems

[0009] The desulfurizer disclosed in the present invention is characterized in that it is a desulfurizer for removing sulfur compounds from a raw gas containing sulfur compounds, and the desulfurizer contains a metal organic structure, which contains copper ions, trimesic acid and a benzoic acid-based compound. The benzoic acid-based compound is a compound obtained by replacing the hydrogen atom at the meta-position or para-position relative to the carboxyl group of benzoic acid with a substituent, and the electron donating property is higher than that of benzoic acid.

[0010] Effects of the Invention

[0011] The desulfurizing agent of the present disclosure donates electrons to copper ions of the metal organic structure by using a benzoic acid compound having a higher electron donating property than benzoic acid, thereby increasing the affinity of the sulfur compound for copper ions and improving the adsorption capacity of the sulfur compound.

[0012] In addition, since the metal organic structure constituting the desulfurizer disclosed in the present invention is a structure in which a part of the trimesic acid in the metal organic structure composed of copper ions and trimesic acid is replaced by a benzoic acid-based compound, it has more pores with large pore sizes compared to the metal organic structure composed of copper ions and trimesic acid, thereby improving the adsorption capacity of sulfur compounds.

[0013] Therefore, it is possible to provide a desulfurizing agent that can reduce the amount of the desulfurizing agent filled in the desulfurizer and can reduce the size of the desulfurizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is a schematic diagram showing a desulfurizer filled with a desulfurizing agent according to the first embodiment. DETAILED DESCRIPTION

[0015] (Insights that form the basis of this disclosure, etc.)

[0016] At the time of the present disclosure, the inventors of the present invention realized that a metal organic structure composed of copper ions and trimesic acid existed as a desulfurizing agent for removing sulfur compounds from a raw material gas containing sulfur compounds, and that the sulfur compounds contained in the raw material gas could be removed simply and efficiently.

[0017] However, the adsorption amount is low compared to the theoretical adsorption amount of sulfur compounds estimated from the content of copper ions in the structure serving as active sites, and it is impossible to achieve miniaturization of the desulfurizer.

[0018] Under such circumstances, the inventors of the present invention have come up with the following idea: when a metal-organic structure composed of copper ions and trimesic acid in which a part of the trimesic acid is replaced by a benzoic acid-based compound having a higher electron-donating property than benzoic acid is used as a desulfurizing agent, the benzoic acid-based compound donates electrons to the copper ions of the metal-organic structure, thereby increasing the affinity of the sulfur compound to the copper ions, thereby improving the adsorption capacity of the sulfur compound. Furthermore, compared with the metal-organic structure composed of copper ions and trimesic acid, the metal-organic structure has more pores with large pore sizes, thereby improving the adsorption capacity of the sulfur compound.

[0019] The present disclosure provides a desulfurizer capable of reducing the volume of the desulfurizer filled in the desulfurizer and downsizing the desulfurizer.

[0020] Below, while referring to the attached Figure 1 The embodiments are described in detail. However, sometimes more detailed description than necessary is omitted. For example, sometimes detailed description of well-known matters or repeated description of substantially the same structure is omitted.

[0021] It should be noted that the drawings and the following descriptions are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0022] (Implementation Method 1)

[0023] Below, use Figure 1 Implementation method 1 will be described.

[0024] [1-1. Structure]

[0025] like Figure 1As shown, the desulfurizing agent 4 of this embodiment is filled (loaded) in a storage container 1. The storage container 1 is provided with an inlet 2 at one end in the long side direction for allowing the raw gas before desulfurization to flow into the storage container 1, and an outlet 3 at the other end for allowing the raw gas after desulfurization to flow out of the storage container 1.

[0026] The desulfurization device 10 is configured such that a raw material gas before desulfurization flows into an inlet portion 2 of a storage container 1 , and the raw material gas desulfurized by a desulfurizing agent 4 filled (carried) in the storage container 1 flows out from the storage container 1 .

[0027] The inlet portion 2 is a pipe for supplying a raw material gas.

[0028] The raw material gas in the present embodiment is city gas having methane as a main component and contains tetrahydrothiophene (hereinafter referred to as THT) as a sulfur compound at a concentration of 15 ppm.

[0029] The outlet portion 3 is a pipe for discharging the raw gas from which THT has been removed by the desulfurizing agent 4 .

[0030] The raw gas discharged from the outlet portion 3 is supplied to a hydrogen generator (not shown) that generates hydrogen, is converted into hydrogen by a reforming catalyst (not shown) in the hydrogen generator, and is used in a hydrogen utilizing device (not shown) such as a fuel cell.

[0031] The desulfurizing agent 4 includes a metal organic structure that adsorbs sulfur compounds. The metal organic structure includes copper ions, trimesic acid, and a benzoic acid compound. The benzoic acid compound is a compound in which a hydrogen atom at a meta or para position relative to a carboxyl group of benzoic acid is replaced with a substituent, and has a higher electron donating property than benzoic acid.

[0032] The desulfurizing agent 4 in this embodiment uses Cu-BTC-OH-BA-p containing 4-hydroxybenzoic acid as a benzoic acid-based compound. The 4-hydroxybenzoic acid has a structure in which the hydrogen atom at the para position relative to the carboxyl group of benzoic acid is substituted with a hydroxyl group (Example 1).

[0033] (Method for synthesizing metal organic structures)

[0034] The metal organic structure is synthesized by a well-known solvothermal method.

[0035] First, a copper ion source, trimesic acid, and a benzoic acid compound are added to an organic solvent to prepare a raw material solution, and then the raw material solution is heated to grow crystals of the metal organic structure.

[0036] Since unreacted copper ion source and trimesic acid remain in the obtained crystals of the metal-organic structure, they are removed by washing and then dried to obtain a powdery metal-organic structure.

[0037] It should be noted that the molar ratio of the benzoic acid compound contained in the metal organic structure is preferably 10% or more and 50% or less relative to trimesic acid.

[0038] It is generally believed that Cu-BTC has a plurality of micropores. When the molar ratio is greater than 50%, two or more benzoic acids or isophthalic acids are adjacent, thereby increasing the number of mesopores. The increase in mesopores means the collapse of the three-dimensional structure of the metal organic structure, resulting in a decrease in the specific surface area, and therefore it is not preferably used as a desulfurizing agent. In this embodiment, the molar ratio of the benzoic acid compound is 30% relative to trimesic acid.

[0039] Hereinafter, an example of a method for synthesizing Cu-BTC-OH-BA-p, which is a metal organic structure of Example 1 in Embodiment 1, will be described in detail.

[0040] In the present embodiment, Cu-BTC-OH-BA-p (Example 1) synthesized using 4-hydroxybenzoic acid as a benzoic acid-based compound will be described.

[0041] First, anhydrous copper sulfate (3.6 mmol), trimesic acid (1.6 mmol), and 4-hydroxybenzoic acid (0.48 mmol) were mixed in ethylene glycol (40 mL) to prepare a raw material solution in which the molar ratio of 4-hydroxybenzoic acid to trimesic acid was 30%.

[0042] The raw material solution was added to a sealed container and heated at 120° C. for 24 hours to obtain a product. Furthermore, the precipitate was washed and dried at 120° C. to obtain Cu-BTC-OH-BA-p (Example 1).

[0043] Cu-BTC-CH3-BA-p (Example 2) was synthesized by using 4-methylbenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 4-Methylbenzoic acid is a benzoic acid compound having a structure obtained by replacing the hydrogen atom at the para position relative to the carboxyl group of benzoic acid with a methyl group.

[0044] Cu-BTC-NH2-BA-p (Example 3) was synthesized by using 4-aminobenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 4-Aminobenzoic acid is a benzoic acid compound having a structure obtained by replacing the hydrogen atom at the para position relative to the carboxyl group of benzoic acid with an amino group.

[0045] Cu-BTC-CH3-BA-m (Example 4) was synthesized by using 3-methylbenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of (Example 1). 3-Methylbenzoic acid is a benzoic acid compound having a structure obtained by replacing the hydrogen atom at the meta position relative to the carboxyl group of benzoic acid with a methyl group.

[0046] Cu-BTC-NH2-BA-m (Example 5) was synthesized by using 3-aminobenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 3-Aminobenzoic acid is a benzoic acid compound having a structure obtained by replacing the hydrogen atom at the meta position relative to the carboxyl group of benzoic acid with an amino group.

[0047] Cu-BTC-BA was synthesized by using benzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of (Example 1) (Comparative Example 1).

[0048] Cu-BTC-OH-BA-m (Comparative Example 2) was synthesized by using 3-hydroxybenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 3-Hydroxybenzoic acid is a benzoic acid compound having a structure in which the hydrogen atom at the meta position relative to the carboxyl group of benzoic acid is replaced with a hydroxyl group.

[0049] Cu-BTC-NO2-BA-p (Comparative Example 3) was synthesized by using 4-nitrobenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 4-Nitrobenzoic acid is a benzoic acid compound having a structure in which the hydrogen atom at the para position relative to the carboxyl group of benzoic acid is replaced by a nitro group.

[0050] Cu-BTC-Cl-BA-p (Comparative Example 4) was synthesized by using 4-chlorobenzoic acid instead of 4-hydroxybenzoic acid in the metal organic structure of Example 1. 4-Chlorobenzoic acid is a benzoic acid compound having a structure in which the hydrogen atom at the para position relative to the carboxyl group of benzoic acid is replaced by a chlorine group.

[0051] [1-2. Operation]

[0052] The following operation and effects are described for the desulfurizing agent 4 having the above structure.

[0053] A raw material gas containing THT at a concentration of 15 ppm is supplied to the inlet 2 of the storage container 1. The supplied raw material gas passes through the storage container 1 while contacting the desulfurizing agent 4 inside the storage container 1. The desulfurizing agent 4 removes THT from the raw material gas, and thus the raw material gas from which THT is removed to 20 ppb or less is discharged from the outlet 3.

[0054] (Sulfur adsorption performance evaluation)

[0055] The following describes a method for evaluating the sulfur adsorption performance of the desulfurizing agent 4 mounted on the desulfurizing device 10. The sulfur adsorption performance is expressed by the ratio of the weight of sulfur atoms in adsorbed THT to the weight of the desulfurizing agent 4, that is, THT adsorption capacity (wt%).

[0056] The THT adsorption capacity can be evaluated as follows: introduce the sample and THT gas into a sealed bag, place it at 60°C for 24 hours, analyze the THT concentration in the bag, measure the THT adsorption capacity relative to multiple equilibrium concentrations, assume that the adsorbate molecules are adsorbed in a single molecular layer, calculate the adsorption isotherm using the Langmuir formula, and calculate the adsorption capacity at 15 ppm.

[0057] (Table 1) shows the THT adsorption capacity at 15 ppm of each sample of Examples 1 to 5 and Comparative Examples 1 to 5. In addition, for the substances to which the benzoic acid compound is added, the σ value (the substituent constant determined by the type and position of the substituent in the proportional constant represented by the Hammett equation) indicating the electron withdrawal of the benzoic acid compound is also shown. Samples with a negative σ value are samples with higher electron donating properties than benzoic acid.

[0058] [Table 1]

[0059]

[0060] As shown in (Table 1), the samples of Examples 1 to 5 having negative σ values ​​showed higher THT adsorption capacity than Cu-BTC-BA of Comparative Example 1.

[0061] In addition, the samples of Comparative Examples 2 to 4 having positive σ values ​​showed THT adsorption capacities lower than those of Cu-BTC-BA of Comparative Example 1.

[0062] In addition, as shown in Comparative Example 5, the metal-organic structure Cu-BTC, which is composed of copper ions and trimesic acid and does not contain a benzoic acid-based compound, has a lower THT adsorption capacity than Comparative Example 1.

[0063] [1-3. Effects, etc.]

[0064] As described above, in this embodiment, the desulfurizing agent 4 is a desulfurizing agent for removing sulfur compounds from a raw material gas containing sulfur compounds, and the desulfurizing agent 4 includes a metal organic structure, and the metal organic structure includes copper ions, trimesic acid, and a benzoic acid compound. The benzoic acid compound is a compound obtained by replacing a hydrogen atom at a meta-position or a para-position relative to a carboxyl group of benzoic acid with a substituent, and has a higher electron donating property than benzoic acid.

[0065] Thus, the benzoic acid-based compound having a higher electron-donating property than benzoic acid donates electrons to the copper ions of the metal organic structure, thereby increasing the affinity of the sulfur compound for the copper ions, thereby improving the adsorption capacity of the sulfur compound.

[0066] In addition, the metal organic structure constituting the desulfurizer in the present disclosure is a structure in which a part of the trimesic acid in the metal organic structure composed of copper ions and trimesic acid is replaced by a benzoic acid-based compound. Therefore, compared with the metal organic structure composed of copper ions and trimesic acid, there are more pores with large pore sizes, thereby improving the adsorption capacity of sulfur compounds.

[0067] Therefore, it is possible to provide a desulfurizing agent that can reduce the amount of the desulfurizing agent 4 filled in the desulfurizer (housing container 1 ) and can reduce the size of the desulfurizer (housing container 1 ).

[0068] In addition, the benzoic acid compound may be 4-hydroxybenzoic acid.

[0069] Thus, 4-hydroxybenzoic acid, which has a higher electron donating property than benzoic acid, donates electrons to the copper ions of the metal organic structure, thereby increasing the affinity of the sulfur compound for copper ions and further increasing the size of the functional group (substituent) so that the pores of the metal organic structure are not blocked, thereby further improving the sulfur adsorption capacity.

[0070] In addition, the benzoic acid compound may be 4-methylbenzoic acid.

[0071] Thus, the copper ions of the metal organic structure are supplied with electrons by 4-methylbenzoic acid, which has a higher electron donating property than benzoic acid, thereby increasing the affinity between the sulfur compound and the copper ions and further improving the sulfur adsorption capacity. At the same time, the cost of the desulfurizing agent can be reduced by using inexpensive 4-methylbenzoic acid.

[0072] Therefore, it is possible to provide a desulfurizing agent that is inexpensive and can reduce the amount of the desulfurizing agent 4 filled in the desulfurizer (storage container 1 ), thereby downsizing the desulfurizer (storage container 1 ).

[0073] In addition, the benzoic acid compound may be 4-aminobenzoic acid.

[0074] Thus, 4-aminobenzoic acid, which has a higher electron donating property than benzoic acid, donates electrons to copper ions in the metal organic structure, thereby increasing the affinity of the sulfur compound to copper ions. The basic functional group further increases the affinity to the sulfur compound, thereby further improving the sulfur adsorption capacity.

[0075] Therefore, it is possible to provide a desulfurizing agent that can reduce the amount of the desulfurizing agent 4 filled in the desulfurizer (housing container 1 ) and can reduce the size of the desulfurizer (housing container 1 ).

[0076] (Other Embodiments)

[0077] As described above, as an example of the technology disclosed in this application, embodiment 1 is described. However, the technology in the present disclosure is not limited thereto, and can also be applied to embodiments that have been changed, replaced, added, omitted, etc. In addition, the various components described in embodiment 1 can also be combined to form a new embodiment.

[0078] Here, other embodiments are exemplified below.

[0079] In the first embodiment, city gas containing methane as a main component is exemplified as the raw material gas, but LPG, natural gas, or hydrogen may also be used.

[0080] It should be noted that the above-described embodiments are merely examples of the technology in the present disclosure, and various changes, substitutions, additions, omissions, etc. may be made within the scope of the claims or the scope of their equivalents.

[0081] Industrial Applicability

[0082] The present disclosure can be applied to a desulfurization method for removing sulfur compounds contained in raw gas. Specifically, the present disclosure can be applied to a fuel cell system equipped with a hydrogen generation device that generates hydrogen from city gas or LPG, a hydrogen production device, a fuel cell system that generates electricity using hydrogen containing sulfur compounds, and the like.

Claims

1. A desulfurizing agent, characterized in that: It is a desulfurizing agent for removing sulfur compounds from a raw gas containing sulfur compounds. The desulfurizing agent comprises a metal organic structure, The metal organic structure comprises copper ions, trimesic acid and a benzoic acid compound. The benzoic acid-based compound is a compound obtained by replacing the hydrogen atom at the meta-position or para-position relative to the carboxyl group of benzoic acid with a substituent, and has a higher electron donating property than benzoic acid.

2. The desulfurizing agent according to claim 1, wherein The benzoic acid compound is 4-hydroxybenzoic acid.

3. The desulfurizing agent according to claim 1, wherein The benzoic acid compound is 4-methylbenzoic acid.

4. The desulfurizing agent according to claim 1, wherein The benzoic acid compound is 4-aminobenzoic acid.

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