Method for desulfurizing gas containing ethanol

Abstract

[Problem] To provide an economically advantageous method which when removing an organic sulfur compound included in a gas containing ethanol, makes it possible to achieve a high removal rate of the organic sulfur compound while suppressing decomposition of ethanol. [Solution] Provided is a gas desulfurization method in which a gas containing ethanol and an organic sulfur compound is brought into contact with a desulfurization agent containing copper and zinc oxide at a temperature of 200 °C to 300 °C in the presence of hydrogen having a hydrogen / ethanol molar ratio of 1 to 10.

Description

Desulfurization method for gases containing ethanol

[0001] The present invention relates to a method for desulfurizing gases containing ethanol.

[0002] In recent years, biomass fuels such as bioethanol have attracted attention as a new energy resource. Bioethanol is obtained by alcoholic fermentation of sugars obtained by saccharifying starch contained in sugarcane juice or grains such as corn. Although carbon dioxide is produced when bioethanol is burned, the raw material plants absorb a corresponding amount of carbon dioxide from the air during their growth process. Therefore, it can be considered that, when totaled from the plant's growth process, it does not increase the concentration of carbon dioxide in the atmosphere, and for this reason, bioethanol is considered a carbon-neutral fuel.

[0003] Ethanol can be used as an automobile fuel by mixing it directly with gasoline, but it can also be used as a raw material for city gas by converting it to methane-dominant gas through a steam reforming reaction on a catalyst (see, for example, Patent Document 1), by adding a predetermined amount of hydrogen and steam and converting it to methane-dominant gas on a catalyst (see, for example, Patent Document 2), or by reacting it with hydrogen remaining in the methane-dominant gas produced by the methane reaction of carbon dioxide on a catalyst to convert it to ethane (see, for example, Patent Document 3).

[0004] When ethanol is converted to hydrocarbons using a catalyst, metal catalysts such as ruthenium, palladium, and nickel are used. However, these metals are poisoned by sulfur compounds, significantly reducing their catalytic activity.

[0005] Bioethanol is known to sometimes contain trace amounts of organic sulfur compounds such as dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO). Since these organic sulfur compounds poison metal catalysts, desulfurization is necessary to remove the organic sulfur compounds contained in bioethanol when converting bioethanol to hydrocarbons such as methane and ethane using catalytic reactions with metal catalysts.

[0006] Hydrodesulfurization (hydrogenated desulfurization), a representative desulfurization method used prior to steam reforming of hydrocarbons, is known as the desulfurization method for petroleum fractions. Hydrodesulfurization is a method that uses a Co-Mo or Ni-Mo hydrodesulfurization catalyst to react organic sulfur compounds in hydrocarbon raw materials with hydrogen, causing hydrocracking, and then removes the generated hydrogen sulfide by adsorption onto a zinc oxide adsorbent. Hydrodesulfurization is widely used in practical applications, such as as a desulfurization process for fuel oil in petroleum refining.

[0007] However, when this method is applied to the desulfurization of alcohols, the oxygen functional groups in the alcohol molecules preferentially act on the active sites of the hydrodesulfurization catalyst or adsorbent, preventing these catalysts and adsorbents from performing optimally. Furthermore, depending on the catalyst or adsorbent used, problems such as the alcohols themselves reacting may occur. For these reasons, it has been pointed out that applying the hydrodesulfurization method, which is a desulfurization method for petroleum fractions, to the desulfurization of alcohols is difficult (see, for example, Patent Document 4).

[0008] When applying the hydrogenation desulfurization method to ethanol, there is also the problem of sulfide formation from ethanol. The reaction of ethanol and hydrogen sulfide to produce ethyl sulfide is an equilibrium reaction, and under normal hydrogenation desulfurization operating conditions, at least a portion of the hydrogen sulfide produced by the decomposition of organosulfur compounds is converted to ethyl sulfide. ２ H ５ OH + H ２ S→C ２ H ５ SH+H ２ O (Reaction 1)

[0009] Compared to hydrogen sulfide, ethyl sulfide is adsorbed more slowly by zinc oxide adsorbents. As a result, adsorption by the zinc oxide adsorbent may be insufficient, and there is a risk that sulfur compounds may slip (remain in the treated fluid) as ethyl sulfide.

[0010] As a method for highly desulfurizing hydrocarbons, a desulfurization method is known in which hydrogen is present in an amount such that the hydrogen / hydrocarbon raw material molar ratio is 0.0005 to 0.4 in a desulfurizing agent obtained by hydrogen-reducing an oxide fired body obtained by impregnating a copper oxide-zinc oxide molded body with nickel, and hydrocarbons are brought into contact at a temperature of 100°C or higher and 400°C or lower (see, for example, Patent Document 5). In this method, hydrogen sulfide generated by the decomposition of organic sulfur compounds on the desulfurizing agent quickly reacts with zinc oxide contained in the desulfurizing agent and is fixed as zinc sulfide, so the problem of ethyl sulfide formation due to the reaction between ethanol and hydrogen sulfide does not occur. However, it is not clear whether this desulfurization method can be applied to the desulfurization of a gas containing ethanol.

[0011] A method is also known in which ethanol is brought into contact with a desulfurizing agent containing silver in a liquid state to adsorb and remove organic sulfur compounds in ethanol (see, for example, Patent Documents 6 and 7). However, this method has practical problems in that a large amount of an expensive desulfurizing agent containing silver is required. Patent Documents 6 and 7 also describe test examples using CuO-ZnO / Al ２ O ３ or NiO / SiO ２ / Al ２ O ３ / ZrO ２ as a desulfurizing agent. However, although there is no detailed description of the test conditions, it is said that even when the temperature is increased and hydrogen is added, the performance does not reach that of silver-doped zeolite.

[0012] In Patent Document 8, in removing sulfur components from hydrocarbons containing sulfur components, a hydrocarbon desulfurization method is described in which a hydrocarbon is brought into contact with a catalyst A obtained by supporting a rare earth element or a compound of a rare earth element on a Y-type zeolite and a catalyst B containing a metal selected from nickel, zinc, and copper or a compound of the metal. In this document, examples of hydrocarbons containing sulfur components include methane, ethane, propane, butane, natural gas, LPG, naphtha, gasoline, kerosene, and mixtures thereof, and it is stated that hydrogen, various alcohols, ethers, etc. may be contained in the raw material hydrocarbon. However, in any of the examples and comparative examples, only examples in which kerosene is used as the hydrocarbon containing sulfur components and the test is conducted under conditions not containing hydrogen or ethanol are shown, and neither any disclosure nor any suggestion is made regarding the influence of the coexistence of ethanol on the desulfurization performance or the effect when hydrogen coexists in addition to ethanol.

[0013] Patent Document 9 describes a hydrogen production apparatus equipped with a hydrodesulfurizer for removing sulfur components in a raw material by a hydrogenation reaction. As a hydrodesulfurization agent, a Cu-Zn-Ni-based catalyst is exemplified. Also, as the raw material, in addition to city gas, natural gas, LPG, etc. mainly composed of methane, alcohols such as methanol and ethanol may be used. However, in this document as well, regarding the difficulty and problems of desulfurization when the raw material is ethanol compared with city gas, natural gas, LPG, etc., neither any disclosure nor any suggestion is made.

[0014] Japanese Patent Application Laid-Open No. 2009-227588, Japanese Patent Application Laid-Open No. 2022-176895, Japanese Patent Application Laid-Open No. 2021-138927, Japanese Patent Application Laid-Open No. 2009-143853, Japanese Patent Application Laid-Open No. 11-61154, International Publication No. 2005 / 063354, International Publication No. 2005 / 063681, Japanese Patent Application Laid-Open No. 2004-67742, International Publication No. 2015 / 118860

[0015] The present invention has been made in view of such a situation, and its object is to relate to the removal of organic sulfur compounds contained in a gas containing ethanol, and to provide a method that is economically advantageous while suppressing the decomposition of ethanol and obtaining a high removal rate of organic sulfur compounds.

[0016] The characteristic configuration of the method for desulfurizing a gas containing ethanol and an organic sulfur compound according to the present invention for achieving the above object is that, in the presence of hydrogen having a hydrogen / ethanol molar ratio of 1 or more and 10 or less, the desulfurizing agent containing copper and zinc oxide is brought into contact at a temperature of 200°C or more and 300°C or less.

[0017] According to the above configuration, in removing the organic sulfur compound in the gas containing ethanol, high desulfurization performance can be obtained even at a relatively low temperature. For this reason, the organic sulfur compound contained in the gas containing ethanol can be removed without using a large amount of expensive desulfurizing agent, and the sulfur compound concentration that slips (leaks) to the subsequent stage (downstream side) of the desulfurizer can be maintained at an extremely low level for a long time. Further, when performing desulfurization, it is not necessary to set a high temperature exceeding 300°C, and since the energy required for heating is also small, it is excellent in energy efficiency and economy. Furthermore, since both the reaction in which ethanol decomposes to generate methane, carbon monoxide, carbon dioxide, and hydrogen and the reaction in which ethanol dehydrogenates to generate acetaldehyde are suppressed, the loss of ethanol in the desulfurization process can also be suppressed.

[0018] A further characteristic configuration of the method for desulfurizing a gas containing ethanol and an organic sulfur compound according to the present invention for achieving the above object is that, in the above configuration, the desulfurizing agent further contains nickel or cobalt.

[0019] According to the above configuration, high desulfurization performance can be obtained even at a low temperature, and stable desulfurization performance can be obtained over a long period.

[0020] Another characteristic configuration of the method for desulfurizing a gas containing ethanol and an organic sulfur compound according to the present invention for achieving the above object is that, in the presence of hydrogen having a hydrogen / ethanol molar ratio of 1 or more and 10 or less and steam having a steam / ethanol molar ratio of 0.06 or more and 0.7 or less, the desulfurizing agent containing nickel, copper, and zinc oxide is brought into contact at a temperature of 200°C or more and 260°C or less.

[0021] According to the above configuration, high desulfurization performance can be obtained even at relatively low temperatures when removing organic sulfur compounds from a gas containing ethanol and water vapor obtained by vaporizing aqueous ethanol. Therefore, desulfurization of aqueous ethanol can be performed without removing water, resulting in excellent energy efficiency and economic advantages.

[0022] Here, commercially available bioethanol contains water. The mass percentage of ethanol is about 95% when obtained by distillation, and about 99.5% even in anhydrous ethanol obtained by a further dehydration process after distillation, with the majority of the remainder being water. Ethanol that has not undergone dehydration treatment contains about 5-15% water by mass. With the above composition, even when using commercially available bioethanol, desulfurization can be performed without removing water.

[0023] [Embodiments] The following describes an embodiment of the present invention of a method for desulfurizing a gas containing ethanol and an organic sulfur compound.

[0024] The desulfurizing agent used in this invention comprises copper and zinc oxide.

[0025] The desulfurizing agent of the present invention is typically manufactured by calcination in air, and is used after being subjected to a reduction treatment in the presence of hydrogen before being subjected to the desulfurization reaction.

[0026] It is presumed that zinc is in an oxidized state (ZnO) both at the time of manufacture and after the reduction treatment.

[0027] Copper, at the stage of being fired in air (the stage of being manufactured), is mainly an oxide (Cu ２ It is composed of O, CuO, and it is presumed to be mainly in a metallic state after reduction treatment.

[0028] In other words, the desulfurizing agent used in the present invention contains zinc oxide and copper oxide during manufacturing, and during use contains zinc oxide and copper (metallic copper), and may also contain copper oxide.

[0029] The desulfurizing agent used in this invention may contain nickel or cobalt in addition to copper and zinc oxide. Nickel is mainly an oxide (NiO) at the stage of firing in air (the stage of manufacture), and is presumed to be mainly in a metallic state after reduction treatment. Cobalt is mainly an oxide (CoO or Co) at the stage of firing in air (the stage of manufacture). ３ O ４ ) and it is presumed that after the reduction treatment, it is mainly in a metallic state.

[0030] In other words, the desulfurizing agent used in the present invention may contain zinc oxide, nickel oxide, and copper oxide during manufacturing, and may contain zinc oxide, nickel (metallic nickel), copper (metallic copper), and may further contain copper oxide and nickel oxide during use. The desulfurizing agent used in the present invention may contain zinc oxide, cobalt oxide, and copper oxide during manufacturing, and may contain zinc oxide, cobalt (metallic cobalt), copper (metallic copper), and may further contain copper oxide and cobalt oxide during use.

[0031] The desulfurizing agent used in the present invention may contain additives such as alumina and silica. These act as binders and have the effect of increasing the strength of the desulfurizing agent. However, since these additives do not contribute to the desulfurization performance, if they are included in large quantities, the desulfurization performance may decrease. When additives are included, it is preferable that their mass ratio to the total desulfurizing agent be 10% or less, more preferably 5% or less.

[0032] [Explanation of the manufacturing method of the desulfurizing agent] There are no restrictions on the manufacturing method of the desulfurizing agent used in the present invention, but it is preferably manufactured by the same method as in Patent Document 5.

[0033] The following are examples of methods for producing the desulfurizing agent used in the present invention. Although an aluminum compound, which is a precursor of aluminum oxide that acts as a binder, is used, it may be replaced with silica sol, or it may be omitted altogether.

[0034] First, copper nitrate (Cu(NO) ３ ) ２ ) and water-soluble copper compounds such as and zinc nitrate (Zn(NO) ３ ) ２A water-soluble zinc compound, such as ), is mixed with an alkaline aqueous solution in the presence of an aluminum compound. In this process, the aluminum compound may be dissolved or in a gel-like state. This mixing then causes a precipitate to form.

[0035] Furthermore, the resulting precipitate is calcined to obtain a mixture of copper oxide, zinc oxide, and aluminum oxide. Hereinafter, this mixture will be referred to as the copper oxide-zinc oxide-aluminum oxide mixture.

[0036] Next, the above mixture is molded to form a copper oxide-zinc oxide-aluminum oxide mixture molded body.

[0037] The above molding can utilize, for example, compression molding, and as a compression molding method, for example, the tableting method can be used.

[0038] The copper oxide-zinc oxide-aluminum oxide mixture molded body can also be one of those commercially available copper oxide-zinc oxide-aluminum oxide mixture molded bodies used as desulfurizing agents, methanol synthesis catalysts, or carbon monoxide conversion catalysts.

[0039] The copper, zinc, and aluminum content in the desulfurizing agent is expressed as a mass ratio (percentage in the desulfurizing agent) of CuO, ZnO, and Al, in the following proportions: 10% to 50% by mass, 30% to 70% by mass, and Al ２ O ３ This is approximately 1% to 10% by mass.

[0040] ZnO is an essential component for fixing sulfur as ZnS. If the amount of ZnO in the formulation is too small, the desulfurization capacity will be reduced.

[0041] Copper has catalytic activity in the decomposition of organic sulfur compounds. In addition, along with this catalytic activity, Cu ２ It also contributes to the fixation of sulfur as S, CuS, etc. Therefore, if the amount of copper in the formulation is too small, desulfurization performance cannot be obtained.

[0042] Al ２ O ３ It contributes to specific surface area and strength. Al ２ O ３ There is a concern that if the prescribed dosage is too low, it will not provide practical strength. On the other hand, Al２ O ３ Since it does not directly contribute to desulfurization, too much of it will reduce desulfurization performance.

[0043] A nickel-containing desulfurizing agent can be obtained, for example, by impregnating the aforementioned copper oxide-zinc oxide-aluminum oxide mixture molded body with an aqueous solution containing nickel and then firing it.

[0044] For preparing nickel-containing aqueous solutions, water-soluble nickel compounds can be used as nickel raw materials. Examples of water-soluble nickel compounds include nickel nitrate, nickel acetate, and nickel chloride.

[0045] Of the nickel raw materials mentioned above, nickel nitrate and nickel acetate are particularly preferred because they have high solubility and are easy to impregnate, and they do not leave chloride ions in the prepared desulfurizing agent, thus preventing the desulfurization performance from being impaired by residual chloride ions.

[0046] The nickel content in the desulfurizing agent is 1.0% to 15% by mass as Ni, based on a mass ratio to the desulfurizing agent. Preferably, it is 2.5% to 6% by mass as Ni, based on a mass ratio to the desulfurizing agent.

[0047] A desulfurizing agent containing cobalt can be obtained, for example, by impregnating the aforementioned copper oxide-zinc oxide-aluminum oxide mixture molded body with an aqueous solution containing cobalt and then firing it.

[0048] For preparing cobalt-containing aqueous solutions, water-soluble cobalt compounds can be used as cobalt raw materials. Examples of water-soluble cobalt compounds include cobalt nitrate, cobalt acetate, and cobalt chloride.

[0049] Among the cobalt raw materials mentioned above, cobalt nitrate and cobalt acetate are particularly preferred because they have high solubility and are easy to impregnate, and they do not leave chloride ions in the prepared desulfurizing agent, thus preventing any impairment of desulfurizing performance due to residual chloride ions.

[0050] The cobalt content in the desulfurizing agent is 1.0% to 15% by mass as Co, relative to the desulfurizing agent. Preferably, it is 2.5% to 6% by mass as Co, relative to the desulfurizing agent.

[0051] Thus, by impregnating a carrier consisting of copper oxide, zinc oxide, and aluminum oxide with an aqueous solution containing a predetermined amount of nickel or cobalt, evaporating it to dryness, and then calcining it, a desulfurizing agent containing nickel or cobalt used in the present invention can be obtained.

[0052] The calcination after the evaporation to dryness described above should be carried out in air at a temperature of approximately 250°C to 350°C for 1 to 10 hours. If the calcination temperature is too low, the decomposition of the nickel or cobalt compound used for support will be insufficient, and the desired performance will not be obtained. If the calcination temperature is too high, the specific surface area of ​​the desulfurizing agent will be reduced, and the desired performance will also not be obtained.

[0053] Nickel or cobalt may be loaded onto the carrier in multiple stages.

[0054] [Description of Desulfurization Method] The present invention provides a method for desulfurizing a gas containing ethanol and an organic sulfur compound, which involves contacting the gas with the desulfurizing agent obtained above under conditions in which hydrogen is present in a predetermined proportion, thereby decomposing and removing the organic sulfur compound contained in the gas.

[0055] In this embodiment, the desulfurization method described is one in which the desulfurizing agent obtained above (the manufactured desulfurizing agent) is subjected to reduction treatment in the presence of hydrogen, and then hydrogen is added in a predetermined proportion to a gas containing ethanol and an organic sulfur compound, and the gas is brought into contact with the mixture to decompose and remove the organic sulfur compound contained in the gas.

[0056] Furthermore, the desulfurization method of the present invention exhibits excellent desulfurization performance against organic sulfur compounds such as dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) contained in bioethanol.

[0057] The desulfurizing agent (the manufactured desulfurizing agent) is reduced by a reduction treatment in the presence of hydrogen before being brought into contact with a gas containing ethanol and organosulfur compounds.

[0058] The temperature used when performing the above reduction treatment is approximately 150°C to 350°C.

[0059] The gas used in the reduction treatment is, for example, an inert gas such as nitrogen to which hydrogen (hydrogen gas) is added in an amount of about 1 to 10 volumes.

[0060] The reduction time is calculated stoichiometrically based on the gas flow rate and hydrogen content used in the reduction process, but it is best to set the reduction time to approximately 1.5 to 3 times that amount.

[0061] If the reduction temperature is too low, the reduction will not be completed, and if it is too high, it will cause a decrease in performance due to the sintering of the desulfurizing agent.

[0062] If the hydrogen concentration (volume concentration of hydrogen gas) of the gas used in the reduction process is too low, a large amount of gas will need to be flowed to complete the reduction, which is economically disadvantageous. Conversely, if the hydrogen concentration of the gas used in the reduction process is too high, a rapid temperature rise will occur due to the heat of reaction between hydrogen and the desulfurizing agent in an oxidized state, which is undesirable. For example, a rapid temperature rise may make it impossible to maintain the predetermined reduction temperature.

[0063] The desulfurization method of the present invention is carried out by filling a desulfurizing agent container with a desulfurizing agent, maintaining the desulfurizing agent at a predetermined temperature by external heating or the like, and passing a gas containing hydrogen-added ethanol and an organic sulfur compound through it.

[0064] Desulfurization reactions do not generate significant heat or endothermic reactions unless the concentration of sulfur compounds is extremely high. Among the decomposition reactions of ethanol, the reaction in which ethanol is dehydrogenated to produce acetaldehyde involves relatively large endothermic reactions. However, as will be described later, in the desulfurization method of the present invention, the dehydrogenation reaction of ethanol is suppressed, so no large temperature changes occur in the desulfurization process. For this reason, the gas containing hydrogen-added ethanol and organic sulfur compounds can be preheated to a temperature suitable for desulfurization, and the reaction can be carried out in an adiabatic state without heating or cooling the desulfurizing agent container itself. For example, the desulfurization reaction can also be carried out by preheating the gas containing ethanol and organic sulfur compounds with hydrogen to about 200°C to 300°C, preferably about 220°C to 300°C, which is the temperature used for the reduction treatment described above, and passing it through a container containing the desulfurizing agent.

[0065] The amount of hydrogen added should be between 1 and 10 in terms of hydrogen / ethanol molar ratio. The hydrogen-ethanol ratio is the ratio of moles of hydrogen to moles of ethanol. If the hydrogen / ethanol molar ratio is less than 1, sufficient desulfurization performance cannot be obtained. Furthermore, the reaction of acetaldehyde production by dehydrogenation of ethanol, and the reaction of ethanol decomposing into hydrogen, carbon monoxide, carbon dioxide, and methane proceed more easily when the hydrogen / ethanol molar ratio is small. Therefore, under conditions where the hydrogen / ethanol molar ratio is less than 1, the loss of ethanol in the desulfurization process will be large. When the desulfurization reaction is carried out with a hydrogen / ethanol molar ratio of about 0.05, which is common in hydrocarbon desulfurization, 30% to 50% of the ethanol may be decomposed and lost in the desulfurization process.

[0066] The desulfurization method of the present invention can also be applied to gases containing water vapor. In this case, it is preferable to use a desulfurizing agent containing nickel, copper, and zinc oxide. The molar ratio of water vapor to ethanol is preferably 0.06 to 0.7, and when it is 0.1 to 0.3, particularly high desulfurization performance can be obtained while suppressing the decomposition of ethanol.

[0067] While higher pressures facilitate the desulfurization reaction, high-pressure reactions increase equipment costs. Therefore, a pressure of 0.1 MPa (absolute pressure, hereafter the same) to 10 MPa is preferable, 0.3 MPa to 3 MPa is more preferable, and 0.5 MPa to 2 MPa is particularly preferable for ensuring sufficient desulfurization performance without compromising economic efficiency.

[0068] Furthermore, while a higher hydrogen partial pressure facilitates the desulfurization reaction, equipment capable of withstanding high hydrogen partial pressures at high pressures is costly. Therefore, a hydrogen partial pressure of 0.05 MPa to 7 MPa is preferable, 0.2 MPa to 2 MPa is more preferable, and 0.3 MPa to 1 MPa is particularly preferable in order to ensure sufficient desulfurization performance without compromising economic efficiency.

[0069] [Description of Examples] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0070] [Example 1] Commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ 45 g of 6% by mass was impregnated with an aqueous solution prepared by dissolving 7.0 g of nickel nitrate hexahydrate (98% purity) in 18 g of pure water, and the mixture was allowed to soak for 3 hours.

[0071] Subsequently, the mixture was evaporated to dryness on a hot plate used as a heater, dried for 1 hour in a drying oven set to 110°C, and then heated to 300°C in a muffle furnace used as a calcination furnace at a heating rate of 2°C per minute in air, and held at 300°C for 1 hour for calcination. This yielded a desulfurizing agent Ni(3)-Cu-ZnO containing 3 mass% Ni.

[0072] A reaction tube made of stainless steel (16 mm inner diameter) was filled with 10 g of the desulfurizing agent Ni(3)-Cu-ZnO to form a desulfurizing agent layer.

[0073] Then, while heating the lower end (outlet side) of the desulfurizing agent layer to maintain a temperature of 250°C, a reducing gas, a mixture of nitrogen gas and 2% hydrogen gas (by volume), was circulated through the desulfurizing agent layer at a flow rate of 60 liters per hour (volume at standard conditions of 0°C and 101.325 kPa), and the reduction treatment was carried out for 2 hours. In other words, the desulfurizing agent Ni(3)-Cu-ZnO was reduced in the presence of hydrogen.

[0074] After the reduction treatment described above, while maintaining the lower end of the desulfurizing agent layer at 250°C, an ethanol-containing gas (hydrogen / ethanol molar ratio of 2) consisting of 150 ppm DMS, 30% ethanol, 60% hydrogen (all by volume) and the remainder nitrogen was circulated into the desulfurizing agent layer at a flow rate of 20 liters per hour (volume at standard conditions of 0°C and 101.325 kPa) while maintaining a pressure of 0.7 MPa (absolute pressure). The ethanol was introduced by vaporizing it, and since this ethanol contained 0.25% by mass of water, the ethanol-containing gas contained 0.2% water vapor by volume.

[0075] Here, nitrogen was added for the convenience of the experimental procedure and is not essential for carrying out the desulfurization method of the present invention.

[0076] The desulfurizing agent outlet gas is reduced to atmospheric pressure and passed through a trap filled with water and cooled on the outside with ice to remove water-soluble components. After that, each component in the gas is treated with dimethyl sulfide (DMS, CH4). ３ SCH ３ ), hydrogen sulfide (H ２ S), methanethiol (CH ３ SH), carbonyl sulfide (COS), dimethyl sulfoxide (DMSO, CH4) ３ SOCH ３ For ethanol-containing gas, the following were analyzed and quantified every two hours from two hours to sixteen hours after the start of gas flow: methane, ethylene, and ethane were analyzed using a gas chromatograph with an FID detector, and hydrogen, carbon monoxide, and carbon dioxide were analyzed using a gas chromatograph with a TCD detector.

[0077] The liquid in the trap was recovered, and acetaldehyde and ethanol were analyzed using a gas chromatograph with an FID detector, while dimethyl sulfide was analyzed using a gas chromatograph with an FPD detector.

[0078] The DMS slip rate, ethanol decomposition rate, and aldehyde production rate in the desulfurizing agent were calculated using the following method. In calculating the flow rates of each component, the nitrogen flow rate (mol / s) remained constant before and after the desulfurizing agent, and the desulfurizing agent outlet gas flow rate was calculated from the analyzed nitrogen concentration. In all examples (Examples 1-23) and comparative examples (Comparative Examples 1-4), including this example, no sulfur compounds other than DMS were detected in the desulfurizing agent outlet gas. DMS slip rate (%) = 100 × [DMS flow rate in desulfurizer outlet gas (mol / s)] / [DMS flow rate in desulfurizer inlet gas (mol / s)] Ethanol decomposition rate (%) = 100 × {[Methane flow rate in desulfurizer outlet gas (mol / s)] + [Carbon monoxide flow rate in desulfurizer outlet gas (mol / s)] + [Carbon dioxide flow rate in desulfurizer outlet gas (mol / s)]} / {2 × [Flow rate of ethanol supplied to desulfurizer inlet (mol / s)]} Aldehyde production rate (%) = 100 × [Acetaldehyde recovered in trap (mol)] / {[Ethanol recovered in trap (mol)] + [Acetaldehyde recovered in trap (mol)]} DMS slip rate [liquid] (%) = 100 × [Amount of DMS recovered in the trap (mol)] / [DMS flow rate in the desulfurizing agent inlet gas (mol / s) × Recovery time (s)]

[0079] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, remained below 1% until 12 hours later, reached 1.7% at 14 hours, and 2.8% at 16 hours.

[0080] The ethanol decomposition rate was 2.1% two hours after the start of ethanol-containing gas circulation, 1.0% after 14 hours, and 0.8% after 16 hours.

[0081] The liquid in the trap was collected in two stages: one hour after the start of the test and again during the last 15 hours of the test. The aldehyde generation rate was 2.3% during the first hour and 3.0% during the last 15 hours, with an overall average of 3.0% throughout the test.

[0082] The DMS slip rate [liquid] was 0 at 1 hour from the start of the test and 0.4% at 15 hours from the end of the test.

[0083] From the changes in DMS slip rate and DMS slip rate [liquid], it can be understood that the DMS contained in the desulfurizer inlet gas is initially almost completely decomposed and fixed by the desulfurizer, but as time passes, a small amount of DMS gradually slips, some of which dissolves in the liquid in the trap, but the majority flows out as gas.

[0084] Focusing on the relatively large amount of DMS leaking out as gas, i.e., the DMS slip rate, and using the time when it is less than 1% as a baseline, it can be evaluated that high desulfurization performance was maintained for 12 hours under the conditions of this embodiment. In addition, since both the ethanol decomposition rate and the aldehyde generation rate were low, it was possible to desulfurize the ethanol-containing gas without the decomposition of ethanol under the conditions of this embodiment.

[0085] [Example 2] The gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 1). In other words, the hydrogen / ethanol molar ratio of the gas supplied to the desulfurizing agent was changed from 2 to 1. Otherwise, the desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 1.

[0086] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, remained below 1% until six hours later, reached 1.8% at eight hours, and 7.6% at fourteen hours later.

[0087] The ethanol decomposition rate was 3.5% two hours after the start of ethanol-containing gas circulation and 1.2% after 14 hours. The aldehyde generation rate averaged 5.2% throughout the test.

[0088] Compared to Example 1, the time required for the DMS slip rate to exceed 1% was shortened from 14 hours to 8 hours, and the ethanol decomposition rate and aldehyde production rate increased. This is thought to be due to the hydrogen / ethanol molar ratio changing from 2 to 1. Nevertheless, even under the conditions of Example 2, the DMS slip rate was less than 0.5% at 2 hours from the start of the test, and both the ethanol decomposition rate and aldehyde production rate were suppressed to low values, indicating that desulfurization of ethanol-containing gas is possible.

[0089] [Example 3] The gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 5% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio 1, water vapor / ethanol molar ratio 0.17). In other words, water vapor was added to the gas supplied to the desulfurizing agent, and the desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 2.

[0090] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, remained below 1% until 10 hours later, reached 2.4% at 12 hours, and 3.9% at 14 hours.

[0091] The ethanol decomposition rate was 4.6% two hours after the start of ethanol-containing gas circulation and 1.7% after 14 hours. The aldehyde generation rate averaged 4.9% throughout the test.

[0092] Compared to Example 2, the time until the DMS slip rate exceeded 1% increased from 8 hours to 12 hours, the aldehyde production rate was similar, and the ethanol decomposition rate increased. The increase in the ethanol decomposition rate is thought to be due to the progress of the ethanol steam reforming reaction. The reason why the DMS slip rate was lower than in Example 2 is not entirely clear, but it is possible that a small amount of water vapor promotes the decomposition of DMS. The results of Example 3 show that, according to the method of the present invention, desulfurization of ethanol-containing gas containing a small amount of water vapor is possible, and that desulfurization treatment can be performed even under conditions where water vapor coexists by vaporizing the ethanol directly without performing a treatment to remove water from aqueous ethanol.

[0093] [Example 4] The gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 20% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio 1, water vapor / ethanol molar ratio 0.67). In other words, the water vapor content of the gas supplied to the desulfurizing agent was increased, and the desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 3.

[0094] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, remained below 1% until 10 hours later, reached 1.1% at 12 hours, and 1.5% at 14 hours.

[0095] The ethanol decomposition rate was 8.7% two hours after the start of ethanol-containing gas circulation and 5.5% after 14 hours. The aldehyde generation rate averaged 5.2% throughout the test.

[0096] Compared to Example 3, the time until the DMS slip rate exceeded 1% and the aldehyde production rate were similar, but the ethanol decomposition rate increased. The increase in the ethanol decomposition rate is thought to be due to the increased water vapor partial pressure, which accelerated the water vapor reforming reaction of ethanol. From the results of Example 4, it is concluded that the method of the present invention can perform desulfurization even under conditions where the water vapor / ethanol molar ratio is about 0.7.

[0097] [Example 5] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 225°C, a desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 1.

[0098] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, but reached 1% after four hours and 9.1% after 14 hours.

[0099] The ethanol decomposition rate was 1.2% two hours after the start of ethanol-containing gas circulation and 0.3% after 14 hours. The aldehyde generation rate averaged 0.9% throughout the test.

[0100] Compared to Example 1, the time required for the DMS slip rate to exceed 1% was shortened. On the other hand, the ethanol decomposition rate and aldehyde generation rate decreased significantly. From the results of Example 5, it was determined that even when the desulfurizing agent temperature is around 225°C, it is possible to desulfurize ethanol-containing gas, and although the desulfurization performance is slightly lower compared to when desulfurization is performed at 250°C, it is possible to suppress the ethanol decomposition rate and aldehyde generation rate and reduce ethanol loss.

[0101] [Example 6] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 225°C, a desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 4.

[0102] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until six hours later, reached 1.7% at eight hours later, and was 5.5% at fourteen hours later.

[0103] The ethanol decomposition rate was 2.5% two hours after the start of ethanol-containing gas circulation and 0.7% after 14 hours. The aldehyde generation rate averaged 1.4% throughout the test.

[0104] [Example 7] Commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ 45 g of 6% by mass was impregnated with an aqueous solution prepared by dissolving 14.5 g of nickel nitrate hexahydrate (98% purity) in 18 g of pure water, and the mixture was allowed to soak for 3 hours.

[0105] Subsequently, the mixture was evaporated to dryness on a hot plate used as a heater, dried for 1 hour in a drying oven set to 110°C, and then heated to 300°C in a muffle furnace using air at a heating rate of 2°C per minute, and held at 300°C for 1 hour for firing. This yielded a desulfurizing agent Ni(6)-Cu-ZnO containing 6 mass% Ni.

[0106] A desulfurization test of ethanol-containing gas was conducted in the same manner as in Example 5, except that Ni(6)-Cu-ZnO was used as the desulfurizing agent instead of Ni(3)-Cu-ZnO.

[0107] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas circulation, remained below 1% until eight hours later, reached 1.4% at ten hours later, and was 2.7% at fourteen hours later.

[0108] The ethanol decomposition rate was 0.8% two hours after the start of ethanol-containing gas circulation and 0.3% fourteen hours later. The aldehyde production rate averaged 1.3% throughout the test.

[0109] [Example 8] Except for changing the gas supplied to the desulfurizing agent to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 5% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 1, water vapor / ethanol molar ratio of 0.17), a desulfurization test of an ethanol-containing gas using a Ni(6)-Cu-ZnO desulfurizing agent was conducted in the same manner as in Example 7.

[0110] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until 10 hours later, reached 1.8% at 12 hours, and was 3.0% at 14 hours later.

[0111] The ethanol decomposition rate was 2.0% two hours after the start of ethanol-containing gas circulation and 0.6% after 14 hours. The aldehyde generation rate averaged 2.4% throughout the test.

[0112] [Example 9] Commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ 45 g of 6% by mass was impregnated with an aqueous solution prepared by dissolving 29.1 g of nickel nitrate hexahydrate (98% purity) in 18 g of pure water, and the mixture was allowed to soak for 3 hours.

[0113] Subsequently, the mixture was evaporated to dryness on a hot plate used as a heater, dried for 1 hour in a drying oven set to 110°C, and then heated to 300°C in a muffle furnace used as a calcination furnace at a heating rate of 2°C per minute in air, and held at 300°C for 1 hour for calcination. This yielded a desulfurizing agent Ni(11)-Cu-ZnO containing 11% by mass of Ni.

[0114] A desulfurization test of ethanol-containing gas was conducted in the same manner as in Example 8, except that Ni(11)-Cu-ZnO was used as the desulfurizing agent instead of Ni(6)-Cu-ZnO.

[0115] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until eight hours later, reached 1.7% at ten hours later, and was 4.5% at fourteen hours later.

[0116] The ethanol decomposition rate was 1.9% two hours after the start of ethanol-containing gas circulation and 0.5% after 14 hours. The aldehyde generation rate averaged 2.4% throughout the test.

[0117] [Example 10] Commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ 45 g of 6% by mass was impregnated with an aqueous solution prepared by dissolving 2.30 g of nickel nitrate hexahydrate (98% purity) in 18 g of pure water, and the mixture was allowed to soak for 3 hours.

[0118] Subsequently, the mixture was evaporated to dryness on a hot plate used as a heater, dried for 1 hour in a drying oven set to 110°C, and then heated to 300°C in a muffle furnace used as a calcination furnace at a heating rate of 2°C per minute in air, and held at 300°C for 1 hour. This yielded a desulfurizing agent Ni(1)-Cu-ZnO containing 1% by mass of Ni.

[0119] A desulfurization test of ethanol-containing gas was conducted in the same manner as in Example 1, except that Ni(1)-Cu-ZnO was used as the desulfurizing agent instead of Ni(3)-Cu-ZnO.

[0120] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until six hours later, reached 1.3% at eight hours later, and was 6.3% at fourteen hours later.

[0121] The ethanol decomposition rate was 2.7% two hours after the start of ethanol-containing gas circulation and 1.1% after 14 hours. The aldehyde generation rate averaged 2.5% throughout the test.

[0122] [Example 11] As a desulfurizing agent, a commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ Except for using 6% by mass of Cu-ZnO (hereinafter referred to as Cu-ZnO), a desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 1.

[0123] The DMS slip rate was 2.0% two hours after the start of ethanol-containing gas distribution, and rose to 42.2% after 14 hours.

[0124] The ethanol decomposition rate was 0.1% two hours after the start of ethanol-containing gas circulation and less than 0.05% after 14 hours. The aldehyde generation rate averaged 2.2% throughout the test.

[0125] While desulfurizing agents that do not contain nickel have slightly lower desulfurization performance, they can keep the rate of ethanol decomposition low.

[0126] [Example 12] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 300°C, a desulfurization test of ethanol-containing gas using a Cu-ZnO desulfurizing agent was carried out in the same manner as in Example 11.

[0127] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until four hours, reached 1.0% after six hours, and was 9.9% after fourteen hours.

[0128] The ethanol decomposition rate was 0.5% two hours after the start of ethanol-containing gas circulation and 0.2% after 14 hours. The aldehyde production rate averaged 7.6% throughout the test.

[0129] [Example 13] Except for changing the gas supplied to the desulfurizing agent to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 20% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 1, water vapor / ethanol molar ratio of 0.67), a desulfurization test of an ethanol-containing gas using a Cu-ZnO desulfurizing agent was conducted in the same manner as in Example 12.

[0130] The DMS slip rate was 1.2% two hours after the start of ethanol-containing gas distribution, and rose to 24.1% after 14 hours.

[0131] The ethanol decomposition rate was 0.3% two hours after the start of ethanol-containing gas circulation and 0.1% after 14 hours. The aldehyde generation rate averaged 18.7% throughout the test.

[0132] [Example 14] Commercially available copper oxide-zinc oxide-aluminum oxide mixture molded body (manufactured by Südchemy Catalysts, MDC-7, 3 mm tablet, CuO: 45% by mass, ZnO: 45% by mass, Al ２ O ３ 45 g of 6% by mass was impregnated with an aqueous solution prepared by dissolving 7.0 g of cobalt nitrate hexahydrate (98% purity) in 18 g of pure water, and allowed to soak for 3 hours.

[0133] Subsequently, the mixture was evaporated to dryness on a hot plate used as a heater, dried for 1 hour in a drying oven set to 110°C, and then heated to 300°C in a muffle furnace used as a calcination furnace at a heating rate of 2°C per minute in air, and held at 300°C for 1 hour. This yielded a desulfurizing agent Co(3)-Cu-ZnO containing 3% by mass of Co.

[0134] A desulfurization test of ethanol-containing gas was conducted in the same manner as in Example 1, except that Co(3)-Cu-ZnO was used as the desulfurizing agent instead of Ni(3)-Cu-ZnO.

[0135] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas flow, remained below 1% until 10 hours later, reached 1.0% at 12 hours later, and was 1.0% at 14 hours later.

[0136] The ethanol decomposition rate was 3.0% two hours after the start of ethanol-containing gas circulation and 2.4% after 14 hours. The aldehyde generation rate averaged 2.2% throughout the test.

[0137] [Example 15] Except for changing the gas supplied to the desulfurizing agent to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 5% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 1, water vapor / ethanol molar ratio of 0.17), a desulfurization test of an ethanol-containing gas using a Co(3)-Cu-ZnO desulfurizing agent was conducted in the same manner as in Example 14.

[0138] The DMS slip rate was 1.1% two hours after the start of ethanol-containing gas distribution and 11.7% after 14 hours.

[0139] The ethanol decomposition rate was 2.3% two hours after the start of ethanol-containing gas circulation and 0.3% fourteen hours later. The aldehyde production rate averaged 4.4% throughout the test.

[0140] [Example 16] Except for changing the gas supplied to the desulfurizing agent to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 30% hydrogen, 20% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 1, water vapor / ethanol molar ratio of 0.67), a desulfurization test of an ethanol-containing gas using a Co(3)-Cu-ZnO desulfurizing agent was conducted in the same manner as in Example 14.

[0141] The DMS slip rate was 1.6% two hours after the start of ethanol-containing gas distribution and 15.1% after 14 hours.

[0142] The ethanol decomposition rate was 2.2% two hours after the start of ethanol-containing gas circulation and 0.3% after 14 hours. The aldehyde generation rate averaged 4.2% throughout the test.

[0143] [Comparative Example 1] A heat-resistant glass reaction tube (14 mm inner diameter) was filled with 10 g of Cu-ZnO desulfurizing agent to form a desulfurizing agent layer. While heating the lower end (outlet side) of this desulfurizing agent layer to maintain a temperature of 250°C, a reducing gas, a mixture of nitrogen gas and 2% hydrogen gas (by volume), was flowed through the desulfurizing agent layer at a flow rate of 60 liters per hour (volume at standard conditions of 0°C and 101.325 kPa), and the reduction treatment was carried out for 2 hours. In other words, the desulfurizing agent Cu-ZnO was reduced in the presence of hydrogen.

[0144] After the reduction treatment described above, while maintaining the lower end of the desulfurizing agent layer at 250°C, an ethanol-containing gas (hydrogen / ethanol molar ratio of 0.04) consisting of 150 ppm DMS, 50% ethanol, 2% hydrogen (all by volume) and the remainder nitrogen was flowed into the desulfurizing agent layer at atmospheric pressure at a flow rate of 20 liters per hour (volume at standard conditions of 0°C and 101.325 kPa).

[0145] The desulfurizing agent outlet gas is passed through a trap filled with water and cooled on the outside with ice to remove water-soluble components, and then each component in the gas is treated with dimethyl sulfide (DMS, CH4). ３ SCH ３ ), hydrogen sulfide (H ２ S), methanethiol (CH ３ SH), carbonyl sulfide (COS), dimethyl sulfoxide (DMSO, CH4) ３ SOCH ３ For ethanol-containing gas, the following were analyzed and quantified every two hours from two hours to sixteen hours after the start of gas flow: methane, ethylene, and ethane were analyzed using a gas chromatograph with an FID detector, and hydrogen, carbon monoxide, and carbon dioxide were analyzed using a gas chromatograph with a TCD detector.

[0146] The liquid in the trap was recovered, and acetaldehyde and ethanol were analyzed using a gas chromatograph with an FID detector.

[0147] The DMS slip rate was 79.3% two hours after the start of ethanol-containing gas flow and 63.1% after 14 hours.

[0148] The ethanol decomposition rate was 0.2% two hours after the start of ethanol-containing gas circulation and 0.1% fourteen hours later. The aldehyde production rate averaged 28.8% throughout the test.

[0149] In Comparative Example 1, most of the DMS contained in the ethanol-containing gas passed through the desulfurizing agent layer. In other words, it can be seen that under the conditions of Comparative Example 1, desulfurization of the ethanol-containing gas hardly progressed. Furthermore, comparing the results of Comparative Example 1 with those of Example 11, it can be seen that Comparative Example 1 had a slightly higher ethanol decomposition rate and an acetaldehyde generation rate that was more than 10 times higher.

[0150] [Comparative Example 2] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 300°C, a desulfurization test of ethanol-containing gas using a Cu-ZnO desulfurizing agent was conducted in the same manner as in Comparative Example 1.

[0151] The DMS slip rate was 47.6% two hours after the start of ethanol-containing gas distribution and 41.3% after 14 hours.

[0152] The ethanol decomposition rate was 0.8% two hours after the start of ethanol-containing gas circulation and 0.3% fourteen hours later. The aldehyde production rate averaged 41.3% throughout the test.

[0153] [Comparative Example 3] Except for using Ni(3)-Cu-ZnO instead of Cu-ZnO as the desulfurizing agent, a desulfurization test of ethanol-containing gas was conducted in the same manner as in Comparative Example 1.

[0154] The DMS slip rate was 9.0% two hours after the start of ethanol-containing gas flow and 18.0% after 14 hours.

[0155] The ethanol decomposition rate was 3.9% two hours after the start of ethanol-containing gas circulation and 1.0% after 14 hours. The aldehyde generation rate averaged 25.2% throughout the test.

[0156] [Comparative Example 4] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 300°C, a desulfurization test of ethanol-containing gas using Ni(3)-Cu-ZnO desulfurizing agent was conducted in the same manner as in Comparative Example 3.

[0157] The DMS slip rate was 2.6% two hours after the start of ethanol-containing gas distribution and 13.4% after 14 hours.

[0158] The ethanol decomposition rate was 17.3% two hours after the start of ethanol-containing gas circulation and 5.1% after 14 hours. The aldehyde generation rate averaged 42.3% throughout the test.

[0159] The results of Examples 1 to 16 and Comparative Examples 1 to 4 are summarized in Table 1.

[0160]

[0161] The criteria for classifying the examples (Examples 1-16) and comparative examples (Comparative Examples 1-4) in this embodiment are that the DMS slip rate measured 2 hours after the start of ethanol-containing gas flow is 2% or less with nickel and 0.5% or less without nickel, the ethanol decomposition rate measured 2 hours and 14 hours after the start of ethanol-containing gas flow is 10% or less, and the aldehyde production rate is 20% or less. Examples (Examples 1-16) are those that satisfy all of the above criteria.

[0162] As is clear from the results of Comparative Examples 1 to 4, when the method conventionally used for the advanced desulfurization of hydrocarbons, which involves contacting a copper-based desulfurizing agent in the presence of hydrogen in an amount such that the hydrogen / hydrocarbon raw material molar ratio is 0.0005 to 0.4, is used for the desulfurization of ethanol-containing gas, not only is sufficient desulfurization performance not obtained, but a considerable proportion of the ethanol is converted to acetaldehyde. Although the desulfurization performance is improved by adding nickel to the copper-based desulfurizing agent, the proportion of ethanol converted to acetaldehyde remains high, and in addition, the decomposition reaction of ethanol into methane, carbon monoxide, carbon dioxide, and hydrogen is significantly accelerated.

[0163] In contrast, the method of the present invention allows for the suppression of ethanol decomposition while achieving a high removal rate of organic sulfur compounds. In particular, high desulfurization performance is easily obtained when the desulfurizing agent contains nickel or cobalt. Furthermore, when the desulfurizing agent contains nickel, a decrease in desulfurization performance is not observed even in the presence of water vapor, and in some cases, the desulfurization performance is improved. For this reason, it can be used particularly suitably for the desulfurization of gases that contain water in addition to ethanol, such as gas obtained by vaporizing aqueous ethanol.

[0164] [Example 17] A reaction tube made of stainless steel (16 mm inner diameter) was filled with 20 g of desulfurizing agent Ni(3)-Cu-ZnO, obtained in the same manner as in Example 1, to form a desulfurizing agent layer.

[0165] Then, while heating the lower end (outlet side) of the desulfurizing agent layer to maintain a temperature of 250°C, a reducing gas, a mixture of nitrogen gas and 3% hydrogen gas (by volume), was circulated through the desulfurizing agent layer at a flow rate of 60 liters per hour (volume at standard conditions of 0°C and 101.325 kPa), and the reduction treatment was carried out for 2 hours. In other words, the desulfurizing agent Ni(3)-Cu-ZnO was reduced in the presence of hydrogen.

[0166] After the reduction treatment described above, while maintaining the lower end of the desulfurizing agent layer at 250°C, an ethanol-containing gas (hydrogen / ethanol molar ratio of 2) consisting of 150 ppm DMS, 30% ethanol, 60% hydrogen (all by volume) and the remainder nitrogen was circulated into the desulfurizing agent layer at a flow rate of 20 liters per hour (volume at standard conditions of 0°C and 101.325 kPa) while maintaining a pressure of 0.7 MPa (absolute pressure). The ethanol was introduced by vaporizing it, and since this ethanol contained 0.24% by mass of water, the ethanol-containing gas contained 0.2% water vapor by volume.

[0167] The desulfurizing agent outlet gas is reduced to atmospheric pressure and passed through a trap filled with water and cooled on the outside with ice to remove water-soluble components. After that, each component in the gas is treated with dimethyl sulfide (DMS, CH4). ３ SCH ３ ), hydrogen sulfide (H ２ S), methanethiol (CH ３SH), carbonyl sulfide (COS), dimethyl sulfoxide (DMSO, CH4) ３ SOCH ３ For ethanol-containing gas, the following were analyzed and quantified every two hours from two hours after the start of gas flow to forty hours after the start of gas flow: methane, ethylene, and ethane were analyzed using a gas chromatograph with an FID detector, and hydrogen, carbon monoxide, and carbon dioxide were analyzed using a gas chromatograph with a TCD detector.

[0168] The liquid in the trap was collected in two parts, the first and second halves of the test. Acetaldehyde, diethyl ether, ethyl acetate, and ethanol were analyzed using a gas chromatograph with an FID detector, and dimethyl sulfide was analyzed using a gas chromatograph with an FPD detector.

[0169] The DMS slip rate and ethanol decomposition rate in the desulfurizing agent were calculated using the same method as in Example 1. Furthermore, the aldehyde yield, ethyl acetate yield, and diethyl ether yield were calculated using the following methods. In calculating the flow rates of each component, the flow rate of nitrogen (mol / s) does not change before and after the desulfurizing agent, and the desulfurizing agent outlet gas flow rate was calculated from the analytical value of nitrogen concentration. Aldehyde yield (%) = 100 × [Acetaldehyde recovered in the trap (mol)] / [Flow rate of ethanol supplied to the desulfurizing agent inlet (mol / s) × Recovery time (s)] Ethyl acetate yield (%) = 100 × 2 × [Ethyl acetate recovered in the trap (mol)] / [Flow rate of ethanol supplied to the desulfurizing agent inlet (mol / s) × Recovery time (s)] Diethyl ether yield (%) = 100 × 2 × [Diethyl ether recovered in the trap (mol)] / [Flow rate of ethanol supplied to the desulfurizing agent inlet (mol / s) × Recovery time (s)]

[0170] The DMS slip rate was less than 0.5% two hours after the start of ethanol-containing gas distribution, and remained below 0.5% until 40 hours later.

[0171] The ethanol decomposition rate was 5.9% two hours after the start of ethanol-containing gas circulation and 3.7% after 40 hours.

[0172] The aldehyde yield was 2.8% in the first half of the test (hereinafter referred to as the first half of the test) and 3.1% in the second half (hereinafter referred to as the second half of the test) of the test conducted for 40 hours from the start of ethanol-containing gas flow. The ethyl acetate yield was 11.6% in the first half of the test and 7.9% in the second half. The diethyl ether yield was 0.3% in both the first and second halves of the test.

[0173] Furthermore, the ratio of the amount of ethanol recovered in the trap to the amount of ethanol supplied to the desulfurizing agent inlet (ethanol recovery rate) was 78% in the first half and 82% in the second half. The sum of the ethanol decomposition rate, aldehyde yield, ethyl acetate yield, diethyl ether yield, and ethanol recovery rate is approximately 100%, suggesting that any by-products other than methane, carbon monoxide, carbon dioxide, acetaldehyde, ethyl acetate, and diethyl ether that were produced were likely to be in trace amounts.

[0174] [Example 18] The desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 17, except that the gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 60% hydrogen, 5% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 2, water vapor / ethanol molar ratio of 0.17).

[0175] [Example 19] Except for changing the amount of desulfurizing agent from 20 g to 10 g, a desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 18.

[0176] [Example 20] The desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 19, except that the pressure used for the desulfurization test was changed from 0.7 MPa (absolute pressure) to 1.5 MPa (absolute pressure).

[0177] [Example 21] Except for changing the holding temperature at the lower end of the desulfurizing agent layer from 250°C to 225°C, a desulfurization test of ethanol-containing gas was carried out in the same manner as in Example 17.

[0178] [Example 22] The desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 21, except that the gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 60% hydrogen, 2% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 2, water vapor / ethanol molar ratio of 0.07).

[0179] [Example 23] The desulfurization test of the ethanol-containing gas was carried out in the same manner as in Example 21, except that the gas supplied to the desulfurizing agent was changed to an ethanol-containing gas consisting of 150 ppm DMS, 30% ethanol, 60% hydrogen, 5% water vapor (all by volume), and the remainder being nitrogen (hydrogen / ethanol molar ratio of 2, water vapor / ethanol molar ratio of 0.17).

[0180] The results of Examples 17 to 23 are summarized in Table 2.

[0181]

[0182] In Example 1, the desulfurization test was conducted with a desulfurization agent amount of 10 g. However, when the desulfurization agent amount was increased to 20 g (Example 17), the DMS slip rate could be maintained at less than 0.5% for 40 hours from the start of ethanol-containing gas flow. When the water vapor / ethanol molar ratio was set to 0.17 (Example 18), the ethanol decomposition rate was slightly higher compared to when no water vapor was added (Example 17), but there was no significant difference in aldehyde yield and ethyl acetate yield.

[0183] On the other hand, when the amount of desulfurizing agent was 10 g (Example 19), the DMS slip rate exceeded 1% 4 hours after the start of ethanol-containing gas flow and reached 3.1% after 14 hours, so the test was terminated before 40 hours were reached.

[0184] In Example 20, when the amount of desulfurizing agent was the same 10 g, but the pressure was set to 1.5 MPa (absolute pressure), the DMS slip rate remained below 1% for 28 hours. Compared to Example 19, the ethanol decomposition rate was also lower, indicating that increasing the pressure improves desulfurization performance and suppresses ethanol decomposition.

[0185] When the holding temperature at the lower end of the desulfurizing agent layer was changed from 250°C to 225°C (Example 21), the DMS slip rate was less than 0.5% 14 hours after the start of ethanol-containing gas flow, remained below 1% until 26 hours, but exceeded 1% at 28 hours and reached 7.7% at 40 hours. Compared to Example 17, the desulfurization performance decreased, but the ethanol decomposition rate, aldehyde yield, and ethyl acetate yield decreased significantly. It is thought that the decrease in temperature suppressed side reactions such as ethanol decomposition.

[0186] When the temperature at the bottom of the desulfurizing agent layer was set to 225°C, the same as in Example 21, and the water vapor / ethanol molar ratio was increased to 0.07 (Example 22), the DMS slip rate after 40 hours decreased to 1.6%. Similarly, when the temperature at the bottom of the desulfurizing agent layer was set to 225°C, the same as in Example 21, and the water vapor / ethanol molar ratio was increased to 0.17 (Example 23), the DMS slip rate after 40 hours decreased to less than 0.5%. In other words, the desulfurization performance improved when water vapor was present. The ethanol decomposition rate increased slightly with increasing water vapor / ethanol molar ratio, but no clear trend was observed for aldehyde yield and ethyl acetate yield.

[0187] The diethyl ether yields were 0.3% (first half of the test) and 0.4% (second half of the test) in Example 21, 0.2% (first half of the test) and 0.1% (second half of the test) in Example 22, and 0.1% (first half of the test) and 0.1% (second half of the test) in Example 23. The diethyl ether yield decreased when water vapor was present. This is thought to be because the production of diethyl ether from ethanol is a dehydration reaction, and the presence of water vapor makes it difficult to produce diethyl ether in equilibrium.

[0188] Furthermore, DMS was not detected in the liquid collected in the traps of Examples 17 to 23 (excluding Example 19, which was terminated midway through the test).

[0189] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention.

[0190] The present invention can be applied, for example, to the desulfurization treatment of ethanol-containing gas to avoid sulfur poisoning of the catalyst when carrying out a catalytic reaction using ethanol containing sulfur compounds as a raw material. The ethanol-containing gas after desulfurization may be used directly in the catalytic reaction, or it may be cooled to condense and separate the ethanol, then heated again to vaporize and use in the catalytic reaction.

Claims

A method for desulfurizing a gas containing ethanol and an organic sulfur compound, comprising contacting a desulfurizing agent containing copper and zinc oxide with hydrogen in the presence of hydrogen in a hydrogen / ethanol molar ratio of 1 to 10 at a temperature of 200°C to 300°C. 　 The method for desulfurizing a gas according to claim 1, wherein the desulfurizing agent further comprises nickel or cobalt. A method for desulfurizing a gas containing ethanol and an organic sulfur compound, comprising contacting a desulfurizing agent containing nickel, copper, and zinc oxide at a temperature of 200°C to 260°C in the presence of hydrogen in a hydrogen / ethanol molar ratio of 1 to 10 and water vapor in a water vapor / ethanol molar ratio of 0.06 to 0.7.

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