JP5278874B2 - Method for removing sulfur compound from gas and method for producing synthetic fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow use of a carbonaceous adsorbent at a temperature above 500&deg;C. <P>SOLUTION: The method for removing a sulfur compound includes a step of passing combustible gas, which is formed by gasification of a carbonaceous raw material, through a porous carbon material at a temperature above 500&deg;C to remove a sulfur compound (H<SB>2</SB>S, COS, CS<SB>2</SB>and the like) in the combustible gas. A desirable material for the porous carbon material carries a metal component. Preferably, the porous carbon material is char obtained from wood-based biomass. The ash content of the char is 3-50 mass% for example. The char usually has a total specific surface area of &ge;200 m<SP>2</SP>/g and a mean pore diameter of 2.0-3.5 nm. In the sulfur compound removal step, a gas passage temperature is set to 600-800&deg;C to decompose part or the whole of the sulfur compound into a simple substance S. The simple substance S contained in the sulfur compound removal gas can be removed by an adsorption removal, liquefaction removal, solidification removal and the like. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a technique for removing a sulfur compound from a gas containing a sulfur compound (sulfur component) such as hydrogen sulfide (H ₂ S) or carbonyl sulfide (COS), more preferably removal of the sulfur compound. More particularly, the present invention relates to a technique for removing carbon disulfide (CS ₂ ) produced therein as a sulfur compound, and particularly, a technique for removing simple S produced during the removal of the sulfur component.

Examples of the gas containing sulfur compounds such as H ₂ S and COS include combustible gas (CO, H ₂ containing gas) generated by gasification of carbonaceous raw materials (woody biomass, coal, etc.), methane fermentation, etc. The biogas obtained from is known. These gases can be used not only as fuel gases in gas turbines, steam turbines, gas engines, fuel cells and the like, but also can be made into synthetic fuels by catalytic reaction. For example, it can be used as a liquefied fuel such as propane and butane; a liquid fuel such as gasoline and light oil; a solid fuel such as wax; and a methanol synthesis catalyst and dimethyl ether. It can be converted into methanol (liquid fuel), dimethyl ether (liquefied fuel), etc. by a synthetic catalyst. However, when used as the fuel gas, it is required to reduce the hydrogen sulfide concentration to a very low concentration (for example, about several tens of ppm to several ppm) (Patent Documents 1 and 2). Further, even in the case of using synthetic fuel, it is required to reduce H ₂ S and COS, which may reduce the activity of chemical catalysts (Fischer-Tropsch catalyst, methanol synthesis catalyst, dimethyl ether synthesis catalyst, etc.) (Patent Document 3, Non-patent document 1).

Patent Document 2 describes that H ₂ S is removed by a dry method using activated carbon, activated coke, activated char obtained from coal, or the like. However, in order to produce activated charcoal or activated coke, or activated char obtained from coal, after obtaining charcoal, coke, or coal-based char by carbonization, carbonization, or coal gasification, respectively, steam is further added. It is necessary to carry out an activation process, etc., and the cost is high. According to Patent Document 2, H ₂ S is released when the temperature reaches 300 ° C. or higher, and the sulfur compound removal treatment at a high temperature cannot be performed.

Patent Document 3 and Non-Patent Document 1 describe that H ₂ S and COS are removed by a dry process using activated carbon, biomass char, or dry distillation char, or activated carbon or dry distillation char supporting Fe. However, in Patent Document 3, if the temperature is higher than 500 ° C., thermal decomposition of the carbonaceous removing agent occurs, and problems such as reduction in the ability to remove sulfur compounds occur. Therefore, the temperature is 500 ° C. or less (preferably 300 to 450 ° C. ) To remove sulfur compounds. In Non-Patent Document 1, the sulfur compound is removed at a temperature of 300 to 450 ° C.
JP-A-9-42612 JP 2003-210933 A JP 2006-143788 A JP 2006-291036 A Sakanishi, 7 others, “Simultaneous removal of H2S and COS using activated carbons and their supported catalysis”, Catalysis Today, 2005 Year 104, 94-100

As will be described later, the sulfur compound removal method of the present invention is characterized by being performed at a high temperature, but it has been found that CS ₂ is produced during the sulfur compound removal treatment at this high temperature. Therefore, when a document describing the removal of CS ₂ was examined, there was Patent Document 4. This Patent Document 4 introduces a method for removing CS ₂ from hydrocarbon oils obtained by thermal decomposition of naphtha, kerosene, light oil, and heavy oil. About the method for removing CS ₂ in gasification gas Has not been reported. CS ₂ has a higher boiling point compared to H ₂ S and COS, and CS ₂ is adsorbed on the inner walls of pipes, gas collectors, and gas sample storage tedra packs at the gas sampling stage. It seems that the existence was not known because it was not detected by chromatography. In fact, according to the study by the present inventors, the sulfur compound removal process at a high temperature of the present invention is performed only by performing on-side continuous measurement while keeping piping and the like in a gas chromatography analyzer using an FPD detector. It was confirmed that CS ₂ was produced. In removing sulfur compounds from the combustible gas by gasification (desulfurization treatment), it is desired to remove not only H ₂ S and COS but also CS ₂ .

  There is no specific example in which a gas having a temperature higher than 500 ° C. is treated with a carbonaceous adsorbent. Although it is described as the cause that the adsorbed component is detached at high temperature, the carbonaceous adsorbent is burnt and pyrolyzed at high temperature, so it is insane to use at a temperature above 500 ° C. That is one of the reasons.

  The present invention has been made paying attention to the above-described circumstances, and is to enable the use of a carbonaceous adsorbent even when the temperature exceeds 500 ° C.

As a result of intensive studies to solve the above problems, the inventors of the present invention have developed a flammable gas (CO, H ₂ -containing gas) generated by gasification of a carbonaceous raw material at a temperature exceeding 500 ° C. The present inventors have found that even if desulfurization treatment (sulfur compound removal treatment) is performed with an adsorbent, the oxygen concentration in the combustible gas is extremely low and the carbonaceous adsorbent does not combust or undergo thermal decomposition.

That is, in the sulfur compound removal method according to the present invention, the combustible gas generated by gasification of the woody biomass is passed through the porous carbon material at a temperature of over 500 ° C., and the sulfur compound (H ₂ S, COS in the combustible gas is passed. , CS _{2 and the} like) (the sulfur compound removing step). The porous carbon material does not carry a metal component. The porous carbon material is preferably granulated or char obtained from woody biomass. The char has an ash content of, for example, 3 to 50% by mass. The char usually has a nitrogen adsorption isotherm of type I (IUPAC), a total specific surface area of 200 m ² / g or more, and an average pore diameter of 2.0 to 3.5 nm. In the sulfur compound removing step, the gas passage temperature may be set to 600 to 800 ° C., and a part or all of the sulfur compound may be decomposed into the simple substance S. The simple substance S contained in the sulfur compound removal gas can be removed by a removal method such as adsorption removal, liquefaction removal, and solidification removal.

The sulfur compound removing method can be applied to the following fuel production method. That is, in the fuel production method,
The woody biomass is partially oxidized with air or oxygen-enriched air and converted to a gas containing CO and H ₂ , and the remaining char is recovered (recovery process).
The sulfur compound contained in the gas is removed by passing the gas containing CO and H ₂ through the recovered char or the particulate sulfur compound remover obtained from the recovered char at a temperature above 500 ° C. (sulfur compound Removal process),
The gas from which sulfur compounds have been removed is hydrocarbonated by a Fischer-Tropsch synthesis reaction (hydrocarbonization step).

  The gas from which the sulfur compound has been removed may be used for the Fischer-Tropsch synthesis reaction, or may be converted to methanol by a methanol synthesis catalyst (methanol conversion step) to produce a liquid fuel, or converted to dimethyl ether by a dimethyl ether synthesis catalyst (dimethyl ether). A liquefied fuel may be produced by a conversion step).

  Also in the sulfur compound removing step in the fuel production method, the gas passage temperature may be set to 600 to 800 ° C., and a part or all of the sulfur compound may be decomposed into the simple substance S. This simple substance S is removed by the simple substance S removal process performed after the sulfur compound removing process and before the hydrocarbonation process. In the simple substance S removal step, the simple substance S contained in the sulfur compound removal gas is removed by a removal method such as adsorption removal, liquefaction removal, and solidification removal.

The adsorption removal, liquefaction removal, or solidification removal of the simple substance S may be performed by passing a sulfur compound removal gas through the porous carbon material,
When the performance of the porous carbon material deteriorates due to adhesion of the simple substance S, the porous carbon material may be heated to separate the simple substance S from the porous carbon material, and a regeneration process for regenerating the porous carbon material may be performed. .

According to the present invention, since the combustible gas (CO, H ₂ -containing gas) generated by gasification of the carbonaceous raw material is a processing target, the sulfur compound removing agent (porous) Gas can be desulfurized (removal of sulfur compounds) without burning or pyrolyzing the carbon material. Moreover, according to the present invention, since the porous carbon material having a controlled pore structure, in a preferred embodiment, char obtained from woody biomass is used, the sulfur compound can be effectively removed from the gas in a dry manner. When char is used, normally discarded char can be effectively used, which is excellent in terms of resource protection and environmental load reduction. Further, in the present invention, in a preferred embodiment, when the temperature is higher than 500 ° C. rather than 500 ° C. or lower, the sulfur compound removal characteristics are improved, and for example, the time for the sulfur compound to break through can be rather extended. Further, in a preferred embodiment, after the sulfur compound is continuously removed, the sulfur compound removal efficiency continues to be removed at a high efficiency without a rapid decrease even after the sulfur compound breakthrough occurs once. be able to. Furthermore, when the sulfur compound removal temperature is set to 600 ° C. or higher, the sulfur compound in the gas can be completely decomposed to the simple substance S. Therefore, when combined with the removal process of the simple substance S (adsorption removal, liquefaction removal, solidification removal, etc.), the sulfur compound can be removed more reliably. It should be noted that a porous carbon material is used for the removal of the simple substance S, and even if this porous carbon material deteriorates due to the removal of the simple substance S, the simple substance S can be separated and recovered from the porous carbon material by a heat desorption process or the like. The carbon material can be regenerated and used repeatedly.

In addition, according to the present invention, when a combustible gas (CO, H ₂ containing gas) obtained by gasification of a carbonaceous raw material is subjected to a catalytic reaction to produce a synthetic fuel, the gasification step is performed between the gasification step and the catalytic reaction step. Since the upper limit temperature of the gas purification process (desulfurization process; sulfur compound removal process) can be increased to the lower limit of the gasification temperature (usually about 800 ° C), only the heat stored in the gasification process is used (ie, external Fischer-Tropsch synthesis, methanol synthesis, and dimethyl ether synthesis can be controlled at an appropriate temperature (about 200 to 300 ° C.) without contributing to energy saving and cost reduction.

I: porous carbon material present invention, a porous dry desulfurization of gases using a carbon material as a sulfur compound removal agent (de H ₂ S, de COS, de CS _2, etc.) technique. Since the porous carbon material has a controlled pore structure, the sulfur compound can be effectively removed from the gas in a dry manner.

  Examples of the porous carbon material include activated carbon, char, etc., preferably char, particularly char obtained from woody biomass (hereinafter referred to as woody char). Woody biomass has a structure in which cellulose is bound with hemicellulose or lignin. Cellulose molecules are arranged in an orderly manner in woody biomass, and hemicellulose and lignin are filled between them. Cellulose molecular chains are self-assembled in plants and are regularly laminated to form microfibrils, and these microfibrils are further aggregated to form wood fibers. The char obtained from woody biomass has a regular pore structure and distribution due to the regular microfibril structure, or 500 ° C despite having a smaller specific surface area and pore volume than activated carbon. A large amount of sulfur compounds can be efficiently removed even under super processing conditions. In char obtained from fossil fuels such as coal char, the microfibril structure has already collapsed at the fossil fuel stage.

  As woody biomass, various woody materials obtained from trees can be used. For example, in addition to wood chips, wood (thinned wood, etc.), remaining wood, saw bark, sawdust, branches, treetops, etc. , Waste materials such as building waste and demolition materials are also included.

The wood-based char is, for example, a char that remains after the wood-based biomass is partially oxidized with air or oxygen-enriched air and gasified (that is, into a gas containing CO and H ₂ ). Details of gasification of woody biomass will be described later. The char remaining after gasification may further improve the sulfur compound removal characteristics at a high temperature exceeding 500 ° C. because of the high ash content.

  The ash content of the wood char is, for example, 3% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more. The upper limit of the content is usually 50% by mass or less, for example 40% by mass or less, particularly 30% by mass or less.

  The porous carbon material (especially wood char) may be used as it is, but is preferably granulated. By granulating (particulate sulfur compound removing agent), the handling property of the porous carbon material (especially wood char) can be enhanced, and the breathability of the processing gas (sulfur compound-containing gas) can also be enhanced. The granulation method is not particularly limited, and a granulation method (for example, a disc granulation method) using an appropriate binder (for example, a liquid that can be distilled off such as water, or an organic or inorganic binder) is employed. It is also possible to adopt a method of extruding the material with an appropriate binder and then cutting it to an appropriate length (extrusion-cutting method), or a classification method (for example, sieving method). May be. The classification method is excellent in that it can be easily granulated. The granulation method and the extrusion-cutting method are excellent in that the powdered char can be used without being discarded. The particle size distribution (by vibration sieving method) of the woody char (sulfur compound removing agent) when granulated is, for example, 70% by mass or more (preferably 80% by mass or more, more preferably 90% by mass or more). ) Passes through a wire mesh with an opening of 8 mm and remains on the wire mesh with an opening of 2 mm.

Various characteristics of the wood char are generally as follows (1) to (3).
(1) Nitrogen adsorption isotherm Generally, the nitrogen adsorption isotherm of the wood char indicates type I (IUPAC). Being belonging to type I (IUPAC) means a structure having developed micropores.

(2) Total specific surface area (BET method)
The total specific surface area of the wood-based char is generally 200 m ² / g or more, preferably 300 m ² / g or more, more preferably 400 m ² / g or more. The upper limit of the total specific surface area can be increased by activation treatment, but when not activated, for example, 800 m ² / g or less, preferably 700 m ² / g or less, more preferably about 600 m ² / g or less. is there. According to the wood-based char, more sulfur compounds can be removed even if the total specific surface area is smaller than that of the activated carbon.

The total pore volume of the wood-based char is generally about 0.2 to 0.5 cm ³ / g, preferably about 0.25 to 0.45 cm ³ / g, more preferably 0.30 to 0 It is about 40 cm ³ / g. According to the wood-based char, more sulfur compounds can be removed even if the total pore volume is smaller than that of activated carbon.

(3) Pore diameter (BET method)
The average pore diameter of the wooden char is generally about 2.0 to 3.5 nm, preferably about 2.2 to 3.3 nm, and more preferably about 2.5 to 3.0 nm.

The porous carbon material can carry a metal component by a treatment such as impregnation and drying (reference invention), but the invention according to the claims does not carry a metal component . In the reference invention, the ability to remove sulfur compounds can be enhanced by supporting the metal component. Preferred metal components include 2A group elements of the periodic table, transition metals (particularly 5A group elements, 7A group elements, and 8 group elements of the periodic table). Particularly preferred metal components are Ca, Fe, V, Mn, etc. (especially Ca, Fe, etc.).

The porous carbon material of the reference invention containing a metal component is desirably fired in a non-oxidizing gas (for example, nitrogen gas). By baking, the sulfur compound removal characteristics can be further enhanced. The firing temperature is, for example, a temperature exceeding 500 ° C., preferably about 550 to 650 ° C.

The metal component of the reference invention is preferably supported in the form of a salt, hydroxide, oxide, or the like. It is inferred that salts and hydroxides become oxides when heated to temperatures above 500 ° C.

The content of the metal component itself after supporting in the reference invention can be selected, for example, within a range of about 0.1 to 70% by mass. In particular, when supporting a Group 2A element of the periodic table, the content of the metal element itself after the support is, for example, about 1 to 70% by mass, preferably about 10 to 60% by mass, and more preferably about 30 to 55% by mass. Moreover, when carrying | supporting a transition metal (especially group 8 element of a periodic table), content of a metal element itself is 0.1-40 mass%, for example, Preferably it is 0.5-30 mass%, More preferably, it is 1-20. It is about mass%.

II: Sulfur compound removal (desulfurization)
The porous carbon material is a sulfur compound at a high temperature from a combustible gas (CO, H ₂ containing gas) generated by gasification (partial oxidation) of a carbonaceous raw material (woody biomass, coal, etc., preferably woody biomass). It is effective to remove. Combustible gas obtained by gasification of carbonaceous material contains almost no oxygen. For example, even if sulfur compound removal treatment is performed at a high temperature of over 500 ° C, the porous carbon material is combusted, pyrolyzed, etc. Without removing the sulfur compound. Also, supporting metal components (especially after supporting and firing) (however, this support corresponds to the reference invention) , and pore structure and ash content when using wood-based char are also high-temperature sulfur. It can contribute to the improvement of the compound removal property.

  The sulfur compound removal temperature is preferably more than 500 ° C. (preferably 550 ° C. or more) and below the lower limit of the gasification temperature (usually about 800 ° C. or less, preferably 700 ° C. or less). By making sulfur compound removal temperature over 500 degreeC, the temperature fall of a sulfur compound removal process can be prevented, and thermal efficiency can be improved.

  The sulfur compound removal temperature may be 600 ° C. or higher (particularly 650 ° C. or higher). When the sulfur compound removal temperature is 600 ° C. or higher, part or all of the sulfur compound can be decomposed into the simple substance S. In addition, this single substance S may be removed separately by providing a removal step different from the sulfur compound removal (details of the separate removal of the simple substance S will be described later).

By the way, as described above, in the sulfur compound removal treatment, if the sulfur compound (H ₂ S, COS) originally contained in the combustible gas generated by gasification of the carbonaceous raw material is only adsorbed and removed by the porous carbon material. not, porous reaction between the carbon material and the sulfur (C + 2S → CS ₂₎ and CS ₂ produced by the decomposition _{(2COS → CO 2 + CS 2} ) in COS also removed by adsorption in the porous carbon material, depending further treatment temperature sulfur A part or all of a compound (H ₂ S, COS, CS _2, etc.) is completely decomposed to a simple substance S. In this sulfur compound removal treatment, a small amount of O ₂ contained in the combustible gas production process can react with the porous carbon material to produce CO. In the case of introducing water vapor, the carbon support is H ₂ O. To produce H ₂ and CO. Therefore, if char produced as a by-product in the process of producing combustible gas is used as the porous carbon material, it can contribute to the improvement of the gasification rate of woody biomass.

Examples of the sulfur compound to be removed include H ₂ S, COS, CS _{2 and the} like. The content of the sulfur compound in the processing gas is, for example, 20 to 1000 ppm (volume basis), preferably 30 to 700 ppm (volume basis), and more preferably 50 to 500 ppm (volume basis).

  The sulfur compound content in the gas after removal of the sulfur compound is, for example, less than 50 ppm (volume basis), preferably less than 30 ppm (volume basis), more preferably less than 20 ppm (volume basis), most preferably 10 ppm or less ( Volume basis) (particularly 5 ppm or less (volume basis)).

  If woody biomass is used as the carbonaceous raw material and char remaining in the gasification step (partial oxidation) is recovered, this char can be used as a porous carbon material (sulfur compound removal agent) in the sulfur compound removal step. Therefore, the char that is normally discarded can be reused in a series of processes, which is excellent in terms of effective use of resources. Therefore, when using woody biomass as the carbonaceous raw material, the gasification step also serves as a manufacturing step for the porous carbon material (sulfur compound removing agent). The operating conditions of the gasification furnace in the gasification step are, for example, as follows.

Input carbonaceous raw material: woody biomass Introduced gas: oxygen or oxygen-enriched air (oxygen content: 21-30% by volume, preferably 23-27% by volume)
Combustion section temperature: about 850 to 1050 ° C
Reducer temperature: about 750-900 ° C
Char production / input carbonaceous raw material: 0.5 to 10% by mass, preferably 1 to 5% by mass
In addition, the said introduction gas may contain water vapor | steam (for example, 0-20 volume%, Preferably 5-10 volume%) as needed.

The recovered char may be used as it is as a sulfur compound remover, or may be granulated and used as a particulate sulfur compound remover. In the reference invention, the particulate sulfur compound remover may carry a metal component.

III: Removal of simple substance S (second removal process)
When removing the single substance S separately from the sulfur compound removal step, the sulfur compound removal process is referred to as a first removal process, and the removal of the single substance S is referred to as a second removal process. The second removal treatment may be performed by adsorption removal, liquefaction removal, solidification removal, or the like alone or in combination as appropriate. A preferable second removal treatment is a treatment method in which the gas containing the simple substance S after the first removal treatment is cooled as necessary, and then communicated with the porous carbon material. By this method, the simple substance S can be removed by adhering (particularly adsorbing) the simple substance S to the porous carbon material as it is in the gas state or while it is liquefied or solidified.
The temperature of the second removal treatment is, for example, a temperature lower than that of the first removal treatment, and is usually lower than the boiling point (445 ° C.) of the simple substance S or the melting point (α type: 113 ° C., β type: 120 ° C., γ type: 107 ° C.) The following range can be selected. A preferable temperature for the second removal treatment is about 250 to 450 ° C.
When a porous carbon material is used for the second removal treatment and the performance of the porous carbon material deteriorates due to adhesion (adsorption) of the simple substance S to the porous carbon material, the porous carbon material is heated (for example, nitrogen The porous carbon material may be regenerated by separating the simple substance S from the porous carbon material by heating to a boiling point or higher of the simple substance S in an inert air flow. Further, the heat-separated simple substance S may be appropriately recovered (for example, recovery by a cooling trap).
The porous carbon material used in the second removal treatment may be char, but activated carbon can also be used very suitably. Since the porous carbon material in the second removal treatment can be regenerated and reused, the material cost has little influence on the manufacturing cost. Rather, activated carbon has a better packing strength than char, and is suitable for the second removal treatment from the viewpoint of handling.

IV: Field of Use The combustible gas from which the sulfur compound has been removed as described above can be made into a synthetic fuel (liquefied fuel, liquid fuel, solid fuel, etc.) by catalytic reaction. For example, by hydrocarbonation by Fischer-Tropsch synthesis, liquefied fuel such as propane and butane; liquid fuel such as gasoline and light oil; and synthetic fuel such as solid fuel such as wax. Further, it can be converted into methanol (liquid fuel), dimethyl ether (liquefied fuel) or the like by a methanol synthesis catalyst or a dimethyl ether synthesis catalyst.

As the Fischer-Tropsch catalyst, known catalysts can be used, and examples thereof include a Co catalyst, an Fe catalyst, a Ru catalyst, a Rh catalyst, a Mo catalyst, and a Th catalyst.
Examples of the methanol synthesis catalyst include a Cu—Zn catalyst and a Pd catalyst.
Examples of the dimethyl ether synthesis catalyst include a Cu-Zn catalyst or a catalyst obtained by adding or physically mixing γ-Al ₂ O ₃ or ZrO ₂ as a dehydration catalyst to a Pd catalyst.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

I: Production of granular wood-based char (sulfur compound remover) Example 1 (Production method of unsupported wood-based char)
In the National Institute of Advanced Industrial Science and Technology (AIST) Biomass Research Center, BTL (Biomass to liquids) bench plant (fixed-bed downdraft gasification furnace) was used, and woody biomass (gasification raw material) with the following specifications was introduced. The gasification continued for 6 hours under the conditions.

(I) Gasification raw material Material name: Eucalyptus chip Shape: 30 mm x 30 mm x 30 mm
Elemental analysis value (anhydrous ashless basis): C 51.0 mass%, H 6.0 mass%, N 0.2 mass%, S 0.015 mass%, O 42.8 mass% [diff. ]
Industrial analysis values: moisture 10.5% by mass, volatiles 73.1% by mass, fixed carbon 15.8% by mass, ash 0.6% by mass
(Ii) Gasification conditions Eucalyptus chip input speed: 9 kg / h
Introduced gas: oxygen-enriched air (oxygen concentration 25% by volume)
Introduction gas flow rate: 9.4 Nm ³ / h
Combustion section temperature in gasifier: 900-1000 ° C
Gasification furnace internal temperature: 800-850 ° C

  The char was taken out at intervals of about 2 hours from the char outlet at the bottom of the gasification furnace. After 6 hours of char (1.8 kg in total) is uniformly mixed, the mixture is sieved to a granular material having an opening of 2 to 4 mm (that is, passing through a sieve with an opening of 4 mm and above a sieve with an opening of 2 mm). Was collected as a sulfur compound remover (hereinafter sometimes referred to as “Char”).

  The ash content and pore characteristics of the obtained granular wood char (sulfur compound remover) were examined as follows. For comparison, the pore characteristics of commercially available activated carbon A (a cylindrical granulated product having a diameter of 3 to 4 mm and a length of 2 to 10 mm, which may be referred to as “AC-A” hereinafter) were also examined.

(1) Ash content A measurement sample (1-2 g) was treated in an air atmosphere at a temperature of 550 ° C. until there was no weight change, and the ash content was determined from the weight change before and after the treatment. The ash content of the granular wood-based char (Char) was 4.7% by mass (based on dry mass), and the ash content of AC-A was 8.7% by mass (based on dry mass).
(2) Nitrogen adsorption isotherm A measurement sample (0.1 to 0.2 g) was vacuum-dried at a temperature of 120 ° C. for 6 hours, and further vacuum-dried overnight at room temperature, and then accurately weighed. Using an automatic gas / vapor adsorption measuring device (BELSORP18) manufactured by Nippon Bell Co., Ltd., adsorption and desorption at a temperature of 77K was automatically measured by a constant volume method using nitrogen as the adsorption gas, and a nitrogen adsorption isotherm of the measurement sample was obtained. .
The results are shown in FIG. As is apparent from FIG. 1, both the granular wood char and the AC-A show a type I (IUPAC) nitrogen adsorption isotherm, which is a structure with developed micropores.

(3) Total specific surface area (S)
Based on the data of the nitrogen adsorption isotherm, a relative pressure (p / p ₀ ) of about 0.05 to _{0 based} on a BET-Plot curve obtained by using BELSORP analysis software (BET method) built in the BELSORP18. .15, an approximate straight line was determined within a range of C values of 100 to 200, and the total specific surface area (S) was calculated by automatic calculation. The C value indicates the heat of adsorption. When the C value is 100 to 200 in the case of carbon nitrogen adsorption, an appropriate specific surface area is obtained. Table 1 shows the calculation results of the total specific surface area (S).

(4) Total pore volume (V)
Using the BELSORP analysis software (BET method) incorporated in the BELSORP 18, the total pore volume (V) was determined from the nitrogen adsorption isotherm data. In the case of granular wood char (Char), the total pore volume (V) is obtained from the amount of nitrogen adsorbed when the relative pressure (p / p ₀ ) is 0.96. In the case of AC-A, the relative pressure (p / p ₀ ) The total pore volume (V) was determined from the nitrogen adsorption amount at 0.90. The results are shown in Table 1.

(5) Average pore diameter (D)
Based on the total pore volume (V) and the total specific surface area (S) determined above, the average pore diameter (D) from the relational expression (D = 4000 V / S) when the pore structure is assumed to be cylindrical. ) Was calculated. The results are shown in Table 1.

  As is clear from Table 1, the granular wood-based char (Char) has a smaller total specific surface area (S) and total pore volume (V) and a larger average pore diameter (D) than AC-A.

(6) Pore distribution (micropore distribution, mesopore distribution)
The distribution of micropores (pores having a pore diameter of 0 to 2.0 nm) when the pore shape is assumed to be a slit type was determined by the MP method (BELSORP analysis software). In addition, the distribution of mesopores (pores having a pore diameter of 2 to 50 nm (pore radius 1 to 25 nm)) when the pore shape is assumed to be a cylinder shape was determined by the DH method (BELSORP analysis software). The micropore distribution is shown in FIG. 2, and the mesopore distribution is shown in FIG.
As apparent from FIGS. 2 and 3, the granular wood char and the activated carbon have different pore distributions. Overall, the former contains more mesopores than the latter.

Reference Example 2 (Production of Fe-supported wood-based char)
20 g of granular wood char with a mesh opening of 2 to 4 mm produced in the same manner as in Example 1 was placed in an eggplant-shaped flask (500 ml). 15.5% by mass of Fe (NO ₃ ) ₃ · 9H ₂ O (ferric nitrate nonahydrate) prepared by dissolving 28.85 g (Fe content: 4.0 g) in 82.7 g of water A NO ₃ ) ₃ aqueous solution (Fe ³⁺ ion concentration: 3.6% by mass) was poured into the eggplant type flask. The eggplant-shaped flask was connected to a rotary evaporator, and while the eggplant-shaped flask was rotated, evacuation and air release operations were repeated three times during 30 minutes. Next, the eggplant-shaped flask was rotated while being attached to an oil bath at a temperature of 60 ° C., and vacuum drying was performed until the sample surface and the inner wall of the flask were free of moisture, thereby impregnating Fe. After the impregnation treatment, the char was taken out, dried in an oven at 105 ° C. for 2 hours, further transferred to a tubular firing furnace and fired at 600 ° C. for 2 hours in a nitrogen stream, and then cooled to room temperature to cool the Fe-supported wood-based char ( Hereinafter, it may be referred to as “Fe / Char”).

Reference example 3
A quartz reaction tube having an inner diameter of 10 mm and a heating part length of 300 mm was filled with 1.00 g of Fe-supported wood-based char (Fe / Char) obtained in Reference Example 2. This quartz reaction tube is set in an electric furnace at 600 ° C., and N ₂ gas containing H ₂ S and COS (H ₂ S concentration: 100 ppm (volume basis), COS concentration: 100 ppm (volume basis)) in the quartz reaction tube is a mass flow controller. While controlling at a flow rate of 100 ml / min. The H ₂ S concentration and COS concentration in the gas after passing were measured by gas chromatography (6890 Series Gas Chromatograph, Agilent Technologies, sample loop: 5 ml, column: HP PLOT / Q capillary column 30 m, split ratio 14.4: 1 And an oven temperature of 120 ° C., a carrier gas: He, a flow rate of 3.6 ml / min, a detector: FPD, 250 ° C.). The piping directly connecting the quartz reaction tube outlet and the gas chromatography inlet was kept warm with a ribbon heater so that the temperature was 60 ° C. Further, the gas concentration of CS ₂ produced in the quartz reaction tube was measured in the same manner. The breakthrough time in the sulfur compound removal experiment was the time taken until the concentrations of H ₂ S, COS, and CS ₂ reached 1 ppm (volume basis; first level) or 50 ppm (volume basis; second level), respectively. Defined in

Reference example 4
Fe was supported on activated carbon (Fe / AC-A) in the same manner as in Reference Example 2 except that 20 g of activated carbon (AC-A) was used instead of wood char. A quartz reaction tube having an inner diameter of 10 mm and a heating part length of 300 mm was charged with 1.00 g of this Fe-supported activated carbon (Fe / AC-A), and in the same manner as in Reference Example 3, sulfur compounds (H ₂ S, COS and CS ₂ ) Investigate the breakthrough time.

Reference Example 5
The same procedure as in Reference Example 3 was performed except that the temperature of the electric furnace in which the quartz reaction tube was set was 800 ° C.
Example 6
The same procedure as in Reference Example 3 was performed except that Char (non-supported char) obtained in Example 1 was used instead of the Fe-supported char.
Comparative Example 1
The same procedure as in Reference Example 3 was performed except that the temperature of the electric furnace in which the quartz reaction tube was set was set to 400 ° C.
Comparative Example 2
Reference Example 4 was performed except that the temperature of the electric furnace in which the quartz reaction tube was set was set to 400 ° C.
The results of Reference Examples 3 to 5, Example 6, and Comparative Examples 1 and 2 are shown in Table 2 and FIGS.

As is clear from Comparative Examples 1 and 2, at a temperature of 400 ° C., the sulfur compound removal characteristics rapidly deteriorate after the sulfur compound breaks through regardless of the type of the porous carbon material. On the other hand, at 600 ° C. in Reference Examples 3 to 4, not only the breakthrough time of each porous carbon material could be extended but also the breakthrough occurred on the first level basis when the sulfur compound concentration became 1 ppm or more. Even afterwards, the sulfur compound can be continuously removed without rapidly deteriorating the sulfur compound removal characteristics. When the temperature is further increased and treated at 800 ° C. ( Reference Example 5), none of H ₂ S, COS, and CS ₂ is detected until 144 hours have passed (detection limit: 0.005 ppm), and very excellent sulfur. The compound removal effect was shown.

By the way, in the example ( reference example, Example) in which the sulfur compound removal temperature is 600 ° C. or more, a white substance is deposited on the inner wall near the exit of the quartz reaction tube as the treatment time elapses regardless of which porous carbon material is used. It started to accumulate. This white substance was confirmed to be simple substance S by elemental analysis. From this result, it can be seen that in the treatment at 600 ° C. or higher, all the sulfur compounds are decomposed by contact with the porous carbon material and decomposed to the simple substance S. In addition, it can be estimated that the decomposition reaction into the simple substance S is almost completely performed in the 800 ° C. treatment in Reference Example 5.

  Further, from Example 6, even when Fe is not supported, Char has a considerable sulfur compound removing effect, and a further sulfur compound removing effect can be expected by raising the temperature. When the unsupported char is used, the metal supporting step on the char is omitted, which is advantageous for reducing the cost of the entire process.

  The sulfur compound removal technology of the present invention can be advantageously used for removing sulfur compounds from a combustible gas obtained from a carbonaceous raw material, and can also be advantageously used for producing a synthetic fuel via the combustible gas.

FIG. 1 shows nitrogen adsorption isotherms for granular wood char (Char) and activated carbon (AC-A). FIG. 2 shows the pore distribution in the micropore region for granular wood char (Char) and activated carbon (AC-A). FIG. 3 shows the pore distribution in the mesopore region for granular wood char (Char) and activated carbon (AC-A). FIG. 4 is a graph showing the relationship between the elapsed time and the H ₂ S reaction tube outlet concentration in the sulfur compound removal experiments of Reference Examples 3 to 5 and Comparative Examples 1 and ₂ . FIG. 5 is a graph showing the relationship between the elapsed time and the COS reaction tube outlet concentration in the sulfur compound removal experiments of Reference Examples 3 to 5 and Comparative Examples 1 and 2.

Claims (16)

  Combustible gas generated by gasification of woody biomass is obtained from woody biomass with an average pore diameter of 2.0 to 3.5 nm that is not supported by a metal component that is a porous carbon material at a temperature of over 500 ° C. The sulfur compound removal method characterized by having the sulfur compound removal process which removes the sulfur compound in combustible gas through the char which is carried out.   The sulfur compound removing method according to claim 1, wherein the porous carbon material is granulated.   The sulfur compound removing method according to claim 1 or 2, wherein the char has an ash content of 3 to 50 mass%.   The sulfur compound removing method according to any one of claims 1 to 3, wherein the char has a nitrogen adsorption isotherm of type I (IUPAC). The sulfur compound removing method according to claim 1, wherein the char has a total specific surface area of 200 m ² / g or more. The sulfur compound removing method according to claim 1, wherein the sulfur compound is at least one selected from H ₂ S, COS, and CS ₂ . In any one of Claims 1-6, the gas passage temperature of a sulfur compound removal process shall be 600-800 degreeC, and it is the method of decomposing | disassembling a part or all of a sulfur compound into the single-piece | unit S,
The sulfur compound removal method which removes the single substance S contained in sulfur compound removal gas further by any one or more removal methods of adsorption removal, liquefaction removal, and solidification removal. A recovery step of partially oxidizing the woody biomass with air or oxygen-enriched air to convert it into a gas containing CO and H ₂ and recovering the remaining char;
The gas containing CO and H ₂ is the recovered char and does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm , or removal of particulate sulfur compounds obtained from the recovered char A sulfur compound removing step of removing sulfur compounds contained in the gas by passing the composition at a temperature above 500 ° C. through an agent that does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm, And a method for producing a synthetic fuel, comprising a hydrocarbonation step in which a gas from which sulfur compounds have been removed is hydrocarbonated by a Fischer-Tropsch synthesis reaction. The gas passage temperature of the sulfur compound removal step is set to 600 to 800 ° C., and part or all of the sulfur compound is decomposed into the simple substance S,
After the sulfur compound removal step and before the hydrocarbonation step, the simple substance S contained in the sulfur compound removal gas is further removed by one or more removal methods of adsorption removal, liquefaction removal, and solidification removal. The synthetic fuel manufacturing method according to claim 8, wherein a removing step is performed. The adsorption removal, liquefaction removal, or solidification removal of the simple substance S is performed by passing a sulfur compound removal gas through the porous carbon material,
10. The regeneration step of regenerating the porous carbon material by heating the porous carbon material to separate the single S from the porous carbon material when the simple substance S adheres and the performance of the porous carbon material deteriorates. The synthetic fuel manufacturing method as described in 2. above. A recovery step of partially oxidizing the woody biomass with air or oxygen-enriched air to convert it into a gas containing CO and H ₂ and recovering the remaining char;
The gas containing CO and H ₂ is the recovered char and does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm , or removal of particulate sulfur compounds obtained from the recovered char A sulfur compound removing step of removing sulfur compounds contained in the gas by passing the composition at a temperature above 500 ° C. through an agent that does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm, And a method for producing a liquid fuel, comprising a methanol conversion step of converting a gas from which sulfur compounds have been removed to methanol using a methanol synthesis catalyst. The gas passage temperature of the sulfur compound removal step is set to 600 to 800 ° C., and part or all of the sulfur compound is decomposed into the simple substance S,
After the sulfur compound removal step and before the hydrocarbonation step, the simple substance S contained in the sulfur compound removal gas is further removed by one or more removal methods of adsorption removal, liquefaction removal, and solidification removal. The method for producing a liquid fuel according to claim 11, wherein a removing step is performed. The adsorption removal, liquefaction removal, or solidification removal of the simple substance S is performed by passing a sulfur compound removal gas through the porous carbon material,
13. When the single substance S adheres and the performance of the porous carbon material deteriorates, a regeneration step is performed in which the porous carbon material is heated to separate the single substance S from the porous carbon material and regenerate the porous carbon material. A method for producing a liquid fuel as described in 1. above. A recovery step of partially oxidizing the woody biomass with air or oxygen-enriched air to convert it into a gas containing CO and H ₂ and recovering the remaining char;
The gas containing CO and H ₂ is the recovered char and does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm , or removal of particulate sulfur compounds obtained from the recovered char A sulfur compound removing step of removing sulfur compounds contained in the gas by passing the composition at a temperature above 500 ° C. through an agent that does not carry a metal component having an average pore diameter of 2.0 to 3.5 nm, And a method for producing a liquefied fuel comprising a dimethyl ether conversion step of converting a gas from which sulfur compounds have been removed to dimethyl ether using a dimethyl ether synthesis catalyst. The gas passage temperature of the sulfur compound removal step is set to 600 to 800 ° C., and part or all of the sulfur compound is decomposed into the simple substance S,
After the sulfur compound removal step and before the hydrocarbonation step, the simple substance S contained in the sulfur compound removal gas is further removed by one or more removal methods of adsorption removal, liquefaction removal, and solidification removal. The method for producing a liquefied fuel according to claim 14, wherein a removing step is performed. The adsorption removal, liquefaction removal, or solidification removal of the simple substance S is performed by passing a sulfur compound removal gas through the porous carbon material,
16. When the simple substance S adheres and the performance of the porous carbon material deteriorates, the porous carbon material is heated to separate the simple substance S from the porous carbon material, and a regeneration step for regenerating the porous carbon material is performed. The manufacturing method of the liquefied fuel as described in 2.