Method for producing hydrogen gas

Abstract

To provide a method for producing hydrogen gas that is inexpensive and highly efficient in production.SOLUTION: A method for producing hydrogen gas comprises mixing biomass with a catalyst and heating the mixture to generate hydrogen gas. The biomass contains chemical pulp and / or cotton.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing hydrogen gas, and more particularly to a method for producing hydrogen gas that is inexpensive and has excellent production efficiency.

Background Art

[0002] In recent years, environmental degradation associated with global warming has become a serious problem. In conventional energy production methods, a large amount of carbon dioxide is generated during the production process, which is increasingly contributing to global warming. Therefore, from the perspective of carbon neutrality, research on power generation and fuel production using biomass such as wood has been actively conducted. Here, "biomass" refers to renewable organic resources derived from living organisms, excluding fossil resources.

[0003] However, in recent years, there has been an emerging competition problem with food in the use of biomass derived from food plants such as corn. Along with this, research on fuel cells and hydrogen power generation using hydrogen as a raw material has become active. Since no carbon dioxide is emitted when hydrogen is used as a fuel, hydrogen fuel is considered to be environmentally friendly. On the other hand, the current main method for producing hydrogen, which is the electrolysis of water to produce hydrogen, is energy inefficient because it uses a large amount of electricity and is not environmentally friendly as a result. Considering the above points, if hydrogen can be produced from biomass, it is considered to be a fuel that is carbon neutral and very friendly to the global environment without generating carbon dioxide.

[0004] As a method for producing hydrogen gas from biomass, a method has been disclosed in which a catalyst is added to biomass and heated to a predetermined temperature to produce hydrogen gas (see Patent Documents 1 to 3). However, in reality, since the biomass as a raw material is an aggregate of various organic substances, it is considered that a large amount of unnecessary substances such as tar are generated during the production of hydrogen gas, reducing the production efficiency of hydrogen gas. Also, the purity of the biomass StylishWhen using a substance (such as pure cellulose) as a raw material, the cost of extraction becomes high, which is not practical. Therefore, in order to stably produce and supply inexpensive hydrogen gas in the future, it is considered necessary to use a raw material with excellent hydrogen gas production efficiency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made paying attention to the above problems, and its object is to provide a method for producing hydrogen gas that is inexpensive and has excellent production efficiency.

[0007] Regarding other objects and effects of the present invention, those skilled in the art will easily understand them by referring to the following description.

Means for Solving the Problems

[0008] The present invention is a method for producing hydrogen gas in which biomass and a catalyst are mixed and heated to generate hydrogen gas, characterized in that the biomass contains chemical pulp and / or cotton. That is, a raw material containing chemical pulp and / or cotton is mixed with a catalyst and heated to generate hydrogen gas.

[0009] According to such a configuration, chemical pulp and cotton contain little lignin and have a higher cellulose purity than other cellulose-containing biomass such as wood and mechanical pulp, so it is considered to be excellent in the production efficiency of hydrogen gas. Also, taboo gases in fuel cells such as ammonia and hydrogen sulfide gas are less likely to be generated.

[0010] Also, in a preferred embodiment of the present invention, the moisture content of the biomass may be 70% by weight or less. According to such a configuration, the generation efficiency of hydrogen gas is further improved.

[0011] In a preferred embodiment of the present invention, it is preferable that the chemical pulp and / or cotton is contained in an amount of 30% by weight or more based on the total amount of the biomass.

[0012] According to such a configuration, since the content ratio of chemical pulp and / or cotton in the raw material biomass is high, other gases are less likely to be generated, and the recovery efficiency of hydrogen gas is also improved. In this case, when the raw material biomass contains both chemical pulp and cotton, the total amount thereof may be contained in an amount of 30% by weight or more based on the total amount of the biomass.

[0013] In another preferred embodiment of the present invention, the chemical pulp may be contained in an amount of 70% by weight or more based on the total amount of the biomass, or may be contained in an amount of 100% by weight.

Advantages of the Invention

[0014] According to the method for producing hydrogen gas according to the present invention, it is possible to efficiently produce hydrogen gas and supply inexpensive hydrogen gas.

[0015] In addition, if the method for producing hydrogen gas according to the present invention is implemented in a paper mill, chemical pulp as a raw material can be procured efficiently and in large quantities. Therefore, it becomes possible to produce hydrogen gas at a lower cost. Furthermore, if the produced hydrogen gas is converted into electrical energy and used for equipment within the paper mill such as a paper-making machine, an energy circulation system can also be constructed. Also, since cotton can be recovered from clothing and fiber scraps, waste can be utilized as biomass, contributing to the effective use of waste.

Brief Description of the Drawings

[0016]

Figure 1

Modes for Carrying Out the Invention

[0017] Next, embodiments of the present invention will be shown and described in detail, but the present invention is not construed as being limited to these descriptions. Also, as long as the effects of the present invention are achieved, the embodiments may be variously modified.

[0018] As described above, in the method for producing hydrogen gas according to the present invention, after mixing biomass containing chemical pulp and / or cotton with a catalyst, heating is performed to generate gas, and at least hydrogen gas is contained in the generated gas.

[0019] In the present invention, chemical pulp, which is a paper-making raw material, can be used as biomass. Since chemical pulp has a higher cellulose purity than other cellulose-containing biomass such as wood and mechanical pulp, it has a high efficiency of generating hydrogen gas and less tar is generated, making it excellent as biomass for raw materials for hydrogen gas production. The wood used as the raw material for the chemical pulp here is not particularly limited, and any of those derived from broad-leaved trees and coniferous trees can be used.

[0020] Also, if the water content rate of the chemical pulp is 70% by weight or less, it is preferable because the hydrogen gas generation efficiency becomes higher. Here, "the water content rate is 70% by weight or less" means that when the total weight of the pulp and water is 100%, the weight of water in the total weight is 70% by weight or less.

[0021] Regarding the chemical pulp used in the present invention, it is preferable from the viewpoint of hydrogen gas generation efficiency to contain bleached pulp (sun-dried pulp), and it is more preferable to use ECF (Elemental Chlorine Free) pulp or TCF (Totally Chlorine Free) pulp with less environmental load as part of the raw material.

[0022] Also, in the present invention, cotton can be used as biomass. Since cotton has a higher cellulose purity than other cellulose-containing biomass such as wood, it has a high hydrogen gas generation efficiency and little tar generation, so it is excellent as biomass for hydrogen gas production raw materials.

[0023] In the present invention, the biomass as the raw material may be a mixture of chemical pulp and / or cotton and other biomass, but the higher the proportion of chemical pulp and / or cotton, the more excellent the hydrogen gas production efficiency. Specifically, the proportion of chemical pulp and / or cotton in the total amount of biomass as the raw material is preferably 30% by weight or more, more preferably 70% by weight or more, and most preferably 100% by weight. In particular, it is preferable that the proportion of chemical pulp is 70% by weight or more, and it is most preferable from the viewpoint of hydrogen gas production efficiency that it consists only of chemical pulp, that is, 100% by weight.

[0024] Other biomass that can be used in combination with the above-described chemical pulp and / or cotton is not particularly limited, and various biomass such as woods, waste paper generated at paper mills, waste paper such as newspapers and magazines, cellulose-containing materials such as paper sludge, sewage sludge containing pulp, fibers such as hemp, silk, and rayon can be used. However, since it is preferable that the biomass has a high cellulose purity, dissolving pulp (DP) is particularly preferable. As methods for procuring these other biomass from within a paper mill, for example, methods such as procuring waste wood and waste wood chips, procuring chemical pulp from the pulp preparation process, and procuring waste paper and paper sludge generated by a paper machine can be mentioned. Also, from the perspective of hydrogen gas production efficiency, it is also preferable to install a hydrogen gas generation device applying the hydrogen gas production method according to the present invention in a pulp mill that uses chemical pulp as a final product and use the chemical pulp as a raw material.

[0025] The method for producing hydrogen gas according to the present invention can be implemented using a known biomass hydrogen gas generation device. In particular, it is environmentally preferable to install a device that generates less tar. Also, from the perspective of hydrogen gas yield, a device in which the heating process is performed in an atmosphere of low oxygen concentration (15% or less) is preferable. Further, from the perspective of ease of extracting the produced hydrogen gas, it is preferable that the heating process is performed in an inert gas atmosphere such as helium gas, nitrogen gas, or argon gas. Also, if it is an atmosphere of low oxygen concentration, it can also be implemented in a high-pressure steam atmosphere (for example, a high-pressure water vapor atmosphere).

[0026] As an example of the principle of a biomass hydrogen gas generator preferable for use in the method for producing hydrogen gas according to the present invention, an apparatus with a principle such as mixing a biomass and a metal compound as a catalyst, such as an iron compound, a nickel compound, a potassium compound, a calcium compound, a sodium compound, or a magnesium compound, and heating them can be cited. The metal compound used here is not limited to the aforementioned metals, and compounds of any metal, such as an alkali metal, an alkaline earth metal, or a transition metal, can be used. In a biomass hydrogen gas generator using such a principle, the heating temperature is about 30 to 600 °C, which is lower than the case where no metal compound is used and is economical. In addition, a biomass hydrogen gas generator utilizing this principle is preferable from an environmental aspect because no tar is generated.

Example

[0027] Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Also, “%” in the examples indicates “% by weight” unless otherwise specified.

[0028] (Example 1) As pulp for papermaking, 1 g of hardwood bleached chemical pulp with a moisture content of 50% and 1 g of potassium hydroxide were mixed with a stirrer (a total of 2 g as raw materials). The mixture of the pulp for papermaking was heated from 30 to 600 °C at a heating rate of 20 °C / min in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed to determine the generation ratio (% by weight based on the raw materials) of hydrogen gas. The amount of hydrogen gas generated was 2.0%.

[0029] (Example 2) In Example 1, hydrogen gas was obtained in the same manner as in Example 1, except that the pulp for papermaking was changed to 1 g of softwood bleached chemical pulp with a moisture content of 50%. The amount of hydrogen gas generated was 2.0%.

[0030] (Example 3) As the pulp for papermaking, 0.3 g of hardwood bleached chemical pulp with a moisture content of 50%, 0.7 g of wood powder with a moisture content of 20%, and 1 g of potassium hydroxide were mixed with a stirrer. The mixture was heated at a rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The generated amount of hydrogen gas was 1.4%.

[0031] (Example 4) In Example 1, hydrogen gas was obtained in the same manner as in Example 1, except that hardwood bleached chemical pulp with a moisture content of 70% was used as the pulp for papermaking. The generated amount of hydrogen gas was 1.5%.

[0032] (Example 5) In Example 1, hydrogen gas was obtained in the same manner as in Example 1, except that hardwood bleached chemical pulp with a moisture content of 20% was used as the pulp for papermaking. The generated amount of hydrogen gas was 2.4%.

[0033] (Example 6) As the pulp for papermaking, 1 g of hardwood bleached chemical pulp with a moisture content of 50% and 1 g of calcium hydroxide were mixed with a stirrer. The mixture was heated at a rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The generated amount of hydrogen gas was 2.0%.

[0034] (Example 7) As the pulp for papermaking, 1 g of hardwood bleached chemical pulp with a moisture content of 50%, 0.7 g of magnesium hydroxide, and 0.3 g of nickel hydroxide were mixed with a stirrer. The mixture was heated at a rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The generated amount of hydrogen gas was 2.0%.

[0035] (Example 8) In Example 1, hydrogen gas was obtained in the same manner as in Example 1, except that bleached hardwood chemical pulp with a moisture content of 5% was used as the pulp for papermaking. The amount of hydrogen gas generated was 2.7%.

[0036] (Example 9) In Example 1, hydrogen gas was obtained in the same manner as in Example 1, except that unbleached hardwood chemical pulp was used as the pulp for papermaking. The amount of hydrogen gas generated was 1.9%.

[0037] (Example 10) As cotton fiber, 1 g of cotton linter and 1 g of potassium hydroxide were mixed with a stirrer (total 2 g as raw materials). The mixture was heated in a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku) from 30 to 600 °C at a heating rate of 20 °C / min in an inert gas (helium gas) atmosphere to quantify hydrogen gas and determine the generation ratio of hydrogen gas (weight% based on the raw materials). The amount of hydrogen gas generated was 1.9%.

[0038] (Example 11) As cotton fiber, 0.4 g of cotton linter, 0.6 g of wood powder, and 1 g of potassium hydroxide were mixed with a stirrer. The mixture was heated in a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku) from 30 to 600 °C at a heating rate of 20 °C / min in an inert gas (helium gas) atmosphere for quantitative analysis of hydrogen gas. The amount of hydrogen gas generated was 1.4%.

[0039] (Example 12) As cotton fiber, 1 g of cotton linter and 1 g of calcium hydroxide were mixed with a stirrer. The mixture was heated in a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku) from 30 to 600 °C at a heating rate of 20 °C / min in an inert gas (helium gas) atmosphere for quantitative analysis of hydrogen gas. The amount of hydrogen gas generated was 2.1%.

[0040] (Example 13) As cotton fiber, 1 g of cotton linter, 0.7 g of magnesium hydroxide, and 0.3 g of nickel hydroxide were mixed with a stirrer. The mixture was heated at a heating rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The amount of hydrogen gas generated was 2.2%.

[0041] (Example 14) As pulp for papermaking, 0.5 g of hardwood bleached chemical pulp with a moisture content of 50% and, as cotton fiber, 0.5 g of cotton linter and 1 g of potassium hydroxide were mixed with a stirrer (total 2 g as raw materials). The mixture was heated at a heating rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed to determine the generation ratio of hydrogen gas (weight % based on the raw materials). The amount of hydrogen gas generated was 1.9%.

[0042] (Comparative Example 1) 1 g of wood powder with a moisture content of 20% and 1 g of potassium hydroxide were mixed with a stirrer. The mixture was heated at a heating rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The amount of hydrogen gas generated was 0.8%.

[0043] (Comparative Example 2) 1 g of corn stalk pieces and 1 g of potassium hydroxide were mixed with a stirrer. The mixture was heated at a heating rate of 20 °C / min to 30 - 600 °C in an inert gas (helium gas) atmosphere using a temperature-programmed desorption gas analyzer (TPD typeR, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The amount of hydrogen gas generated was 0.5%.

[0044] (Comparative Example 3) In Example 1, hydrogen gas was obtained in the same manner as in Example 1 except that the pulp for papermaking was changed to hardwood mechanical pulp with a moisture content of 50%. The amount of hydrogen gas generated was 0.9%.

[0045] (Comparative Example 4) In Example 1, hydrogen gas was obtained in the same manner as in Example 1 except that the pulp for papermaking was changed to softwood mechanical pulp with a moisture content of 50%. The amount of hydrogen gas generated was 0.9%.

[0046] The quantitative results of the hydrogen gas generated in each example and comparative example are shown in Fig. 1. As is clear from Fig. 1, the production methods of Examples 1 to 13 had a larger amount of hydrogen gas generated and were excellent in hydrogen generation efficiency compared to the production methods of Comparative Examples 1 to 4.

[0047] Also, although not described in Fig. 1, in the production methods of Examples 1 to 13, hydrogen gas began to be generated at around 200°C, whereas in the production methods of Comparative Examples 1 to 4, hydrogen gas began to be generated at around 400°C. It was found that the methods of Examples 1 to 13 could produce hydrogen gas more efficiently with heating at a relatively low temperature.

[0048] Furthermore, in Examples 3, 11 and Comparative Examples 1 to 4, carbon monoxide and carbon dioxide were generated in addition to hydrogen gas, presumably because wood powder, corn stalk pieces or mechanical pulp were used. However, in Examples 1, 2, 4 to 10 and 12, 13 using only chemical pulp or cotton, almost no gas other than hydrogen gas was generated, which was also advantageous from the viewpoint of gas recovery. Also, in Comparative Example 1, a small amount of hydrogen sulfide gas was generated.

[0049] As described in detail above, according to the present invention, it is possible to produce hydrogen gas that is extremely environmentally friendly during the manufacturing process, inexpensive for manufacturers, carbon-neutral and environmentally friendly during the manufacturing process, and inexpensive and environmentally friendly for consumers. Furthermore, since the raw material is originally a raw material for papermaking and not a raw material derived from food crops, there is no competition with food.

[0050] In addition, it can serve as an opportunity to popularize inexpensive hydrogen gas in society, and as a result, it becomes possible to contribute to the creation of a society that can reduce the use of fossil fuels. Furthermore, for the paper and pulp industries, it can be an excellent opportunity to produce hydrogen gas while manufacturing paper and paper products and pulp for papermaking, accelerating the production of environmentally friendly products.

Claims

1. A method for producing hydrogen gas by mixing biomass and a catalyst and heating the mixture at 30 to 600 °C to generate hydrogen gas, wherein the biomass contains chemical pulp and / or cotton, and the catalyst contains at least one of a compound of an alkali metal and a compound of an alkaline earth metal. A method for producing hydrogen gas, characterized by this.

2. The method for producing hydrogen gas according to claim 1, characterized in that a compound of a transition metal is further used in combination as the catalyst.

3. The method for producing hydrogen gas according to claim 1, characterized in that the water content rate of the biomass is 70% by weight or less.

4. The method for producing hydrogen gas according to claim 1, characterized in that the chemical pulp and / or cotton is contained in an amount of 30% by weight or more based on the total amount of the biomass.

5. The method for producing hydrogen gas according to claim 1 or 3, characterized in that the chemical pulp is contained in an amount of 70% by weight or more based on the total amount of the biomass.

6. The method for producing hydrogen gas according to claim 1 or 3, characterized in that the chemical pulp is contained in an amount of 100% by weight based on the total amount of the biomass.

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