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 at low cost and with excellent production efficiency. [Background technology]

[0002] In recent years, environmental degradation due to global warming has become a serious problem, and conventional energy production methods generate large amounts of carbon dioxide during the production process, which is a factor that further accelerates global warming. Therefore, from the perspective of carbon neutrality, active research is being conducted into power generation and fuel production using biomass such as wood. Note that "biomass" here refers to renewable organic resources derived from living organisms, excluding fossil resources.

[0003] However, in more recent years, the use of biomass derived from food plants such as corn has begun to compete with food production, leading to active research into fuel cells and hydrogen power generation using hydrogen as a feedstock. Because hydrogen does not emit carbon dioxide when used as fuel, hydrogen fuel is considered environmentally friendly. On the other hand, the current main method of producing hydrogen, the electrolysis of water, requires a lot of electricity and is therefore energy inefficient, making it unenvironmentally unfriendly. Given these points, if hydrogen could be produced from biomass, it would be a carbon-neutral, carbon-free, and extremely environmentally friendly fuel.

[0004] One method for producing hydrogen gas from biomass has been disclosed in which a catalyst is added to biomass and heated to a predetermined temperature (see Patent Documents 1 to 3). However, in reality, the raw material biomass is an aggregate of various organic substances, and therefore large amounts of unwanted substances such as tar are generated during hydrogen gas production, which is thought to reduce the efficiency of hydrogen gas production. Furthermore, when using pure biomass substances (e.g., pure cellulose) as a raw material, the cost of extraction is high, making this method impractical. For this reason, in order to stably produce and supply inexpensive hydrogen gas in the future, it is thought that it will be necessary to use raw materials with excellent hydrogen gas production efficiency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-018955 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-173967 [Patent Document 3] Japanese Patent Application Publication No. 08-59202 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for producing hydrogen gas at low cost and with excellent production efficiency.

[0007] Other objects and advantages of the present invention will be readily apparent to those skilled in the art by reading the following description. [Means for solving the problem]

[0008] The present invention is a method for producing hydrogen gas by mixing biomass with a catalyst and heating the mixture to generate hydrogen gas, wherein the biomass contains chemical pulp and / or cotton. That is, hydrogen gas is generated by mixing a raw material containing chemical pulp and / or cotton with a catalyst and heating the mixture.

[0009] With this configuration, chemical pulp and cotton contain almost no lignin and have a higher cellulose purity than other cellulose-containing biomass such as wood or mechanical pulp, which is thought to result in superior hydrogen gas production efficiency. Furthermore, gases that are prohibited in fuel cells, such as ammonia and hydrogen sulfide, are less likely to be generated.

[0010] In a preferred embodiment of the present invention, the biomass may have a moisture content of 70% by weight or less. With this configuration, the efficiency of hydrogen gas generation is further improved.

[0011] In a preferred embodiment of the present invention, 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] With this configuration, the raw biomass contains a high proportion of chemical pulp and / or cotton, which makes it difficult for other gases to be generated and improves the efficiency of hydrogen gas recovery. In this case, if the raw biomass contains both chemical pulp and cotton, the total amount of these materials should be 30% by weight or more of the total 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, or 100% by weight, based on the total amount of the biomass. [Effects of the Invention]

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

[0015] Furthermore, if the hydrogen gas production method according to the present invention is implemented in a papermaking factory, the raw material chemical pulp can be procured efficiently and in large quantities, making it possible to produce hydrogen gas more cheaply. Furthermore, if the produced hydrogen gas is converted into electrical energy and used in the papermaking factory's equipment, such as paper machines, an energy circulation system can be established. Furthermore, since cotton can be recovered from clothing and textile waste, it can be used as biomass, contributing to the effective use of waste. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a table showing the amount of hydrogen gas generated in each example and comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, the present invention will be described in detail by showing embodiments, but the present invention is not limited to these descriptions. Furthermore, the embodiments may be modified in various ways as long as the effects of the present invention are achieved.

[0018] As described above, the method for producing hydrogen gas according to the present invention involves mixing biomass containing chemical pulp and / or cotton with a catalyst, and then heating the mixture to generate gas, which contains at least hydrogen gas.

[0019] In the present invention, chemical pulp, a raw material for papermaking, can be used as biomass. Chemical pulp has a higher cellulose purity than other cellulose-containing biomass such as wood or mechanical pulp, and therefore has a high hydrogen gas generation efficiency and produces less tar, making it an excellent biomass raw material for hydrogen gas production. There are no particular restrictions on the wood used as the raw material for the chemical pulp, and either wood derived from hardwood or softwood can be used.

[0020] Furthermore, if the moisture content of the chemical pulp is 70% by weight or less, the efficiency of hydrogen gas generation will be higher, which is preferable. Note that "70% by weight or less" here means that when the total weight of pulp and water is 100%, the weight of water in the total weight is 70% by weight or less.

[0021] The chemical pulp used in the present invention preferably contains bleached pulp from the viewpoint of hydrogen gas generation efficiency, and it is even more preferable to use ECF (Elemental Chlorine Free) pulp or TCF (Totally Chlorine Free) pulp, which has a low environmental impact, as part of the raw materials.

[0022] Furthermore, in the present invention, cotton can be used as biomass. Cotton has a higher cellulose purity than other cellulose-containing biomass such as wood, and therefore has a high hydrogen gas generation efficiency and produces less tar, making it an excellent biomass raw material for hydrogen gas production.

[0023] In the present invention, the biomass used as a raw material may be a mixture of chemical pulp and / or cotton with other biomass, but the higher the proportion of chemical pulp and / or cotton, the more efficient the hydrogen gas production. Specifically, the proportion of chemical pulp and / or cotton in the total amount of biomass used as a raw material is preferably 30% by weight or more, more preferably 70% by weight or more, and most preferably 100% by weight. In particular, the proportion of chemical pulp is preferably 70% by weight or more, and 100% by weight, i.e., consisting of only chemical pulp, is most preferable in terms of hydrogen gas production efficiency.

[0024] Other biomass that can be used in combination with the aforementioned chemical pulp and / or cotton is not particularly limited, and various biomass can be used, including wood, paper break generated in paper mills, waste paper such as newspapers and magazines, cellulose-containing materials such as paper sludge, sewage sludge containing pulp, and fibers such as hemp, silk, and rayon. However, biomass with high cellulose purity is preferred, and therefore dissolving pulp (DP) is particularly preferred. Examples of methods for procuring these other biomass from within the paper mill include procuring waste wood and wood chips and chemical pulp from the pulp preparation process, and procuring paper break and paper sludge generated by the paper machine. Furthermore, from the perspective of hydrogen gas production efficiency, it is also preferable to install a hydrogen gas generator employing the hydrogen gas production method of the present invention in a pulp mill that produces chemical pulp as the final product and use the chemical pulp as a raw material.

[0025] The hydrogen gas production method according to the present invention can be carried out using a known biomass hydrogen gas generation device, but from an environmental perspective, it is preferable to install a device that produces little tar. From the viewpoint of hydrogen gas yield, a device in which the heating step is carried out in an atmosphere with a low oxygen concentration (15% or less) is preferred. Furthermore, from the viewpoint of ease of extracting the produced hydrogen gas, a device in which the heating step is carried out in an inert gas atmosphere such as helium gas, nitrogen gas, or argon gas is preferred. Furthermore, the method can also be carried out in a high-pressure steam atmosphere (e.g., a high-pressure water vapor atmosphere) as long as the low-oxygen concentration atmosphere is used.

[0026] An example of a biomass hydrogen gas generator suitable for use in the hydrogen gas production method of the present invention is one based on the principle of mixing biomass with a catalytic metal compound, such as an iron compound, nickel compound, potassium compound, calcium compound, sodium compound, or magnesium compound, and then heating the mixture. The metal compounds used here are not limited to the aforementioned metals; compounds of any metal, including alkali metals, alkaline earth metals, and transition metals, can also be used. Biomass hydrogen gas generators based on this principle require a heating temperature of approximately 30 to 600°C, which is lower than those that do not use metal compounds and is therefore more economical. Furthermore, biomass hydrogen gas generators based on this principle do not produce tar, making them environmentally preferable. [Example]

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

[0028] Example 1 To prepare the paper pulp, 1 g of bleached hardwood chemical pulp with a moisture content of 50% was mixed with 1 g of potassium hydroxide in a mixer (a total of 2 g of raw material). The paper pulp mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed to determine the proportion of hydrogen gas generated (wt % relative to the raw material). The amount of hydrogen gas generated was found to be 2.0%.

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

[0030] Example 3 0.3 g of bleached hardwood chemical pulp with a moisture content of 50% was mixed with 0.7 g of wood flour with a moisture content of 20% and 1 g of potassium hydroxide in a mixer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min in a thermal desorption analyzer (TPD type R, manufactured by Rigaku) ​​and quantitatively analyzed for hydrogen gas. The amount of hydrogen gas generated was 1.4%.

[0031] Example 4 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 papermaking pulp. The amount of hydrogen gas generated was 1.5%.

[0032] Example 5 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 papermaking pulp. The amount of hydrogen gas generated was 2.4%.

[0033] Example 6 1 g of bleached hardwood chemical pulp with a moisture content of 50% was mixed with 1 g of calcium hydroxide in a mixer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku) ​​and quantitatively analyzed for hydrogen gas. The amount of hydrogen gas generated was 2.0%.

[0034] Example 7 1 g of bleached hardwood chemical pulp with a moisture content of 50% was mixed with 0.7 g of magnesium hydroxide and 0.3 g of nickel hydroxide in a mixer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku) ​​and quantitatively analyzed for hydrogen gas. The amount of hydrogen gas generated was 2.0%.

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

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

[0037] Example 10 As cotton fibers, 1 g of cotton linter and 1 g of potassium hydroxide were mixed in a stirrer (2 g total raw material). The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku), and the amount of hydrogen gas was quantified to determine the proportion of hydrogen gas generated (wt % relative to the raw material). The amount of hydrogen gas generated was found to be 1.9%.

[0038] Example 11 0.4 g of cotton linters (cotton fiber), 0.6 g of wood flour, and 1 g of potassium hydroxide were mixed in a mixer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600 °C at a heating rate of 20 °C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku), and quantitative analysis of hydrogen gas was performed. The amount of hydrogen gas generated was 1.4%.

[0039] Example 12 1 g of cotton linter (cotton fiber) and 1 g of calcium hydroxide were mixed in a mixer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a temperature increase rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku) ​​and quantitatively analyzed for hydrogen gas. The amount of hydrogen gas generated was 2.1%.

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

[0041] Example 14 0.5 g of bleached hardwood chemical pulp with a moisture content of 50% was used as paper pulp, and 0.5 g of cotton linter and 1 g of potassium hydroxide were mixed in a mixer (2 g total raw material). The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600 °C at a heating rate of 20 °C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku). Quantitative analysis of hydrogen gas was performed to determine the hydrogen gas generation rate (wt % of the raw material). The resulting hydrogen gas generation rate was 1.9%.

[0042] (Comparative Example 1) 1 g of wood flour with a moisture content of 20% was mixed with 1 g of potassium hydroxide using a stirrer. The mixture was heated in an inert gas (helium gas) atmosphere from 30 to 600°C at a heating rate of 20°C / min using a thermal desorption analyzer (TPD type R, manufactured by Rigaku) ​​and quantitatively analyzed for hydrogen gas. The amount of hydrogen gas generated was 0.8%.

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

[0044] (Comparative Example 3) Hydrogen gas was obtained in the same manner as in Example 1, except that the papermaking pulp 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 Hydrogen gas was obtained in the same manner as in Example 1, except that the papermaking pulp 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 Figure 1. As is clear from Figure 1, the production methods of Examples 1 to 13 generated more hydrogen gas and were superior in hydrogen generation efficiency compared to the production methods of Comparative Examples 1 to 4.

[0047] Furthermore, although not shown in Figure 1, hydrogen gas began to be generated around 200°C in the manufacturing methods of Examples 1 to 13, whereas hydrogen gas began to be generated around 400°C in the manufacturing methods of Comparative Examples 1 to 4. This indicates that the methods of Examples 1 to 13 can produce hydrogen gas more efficiently by 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, possibly because wood flour, corn stalk chips, or mechanical pulp was used, but in Examples 1, 2, 4 to 10, 12, and 13, which used only chemical pulp or cotton, almost no gases other than hydrogen gas were generated, and these were advantageous from the viewpoint of gas recovery. Also, a small amount of hydrogen sulfide gas was generated in Comparative Example 1.

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

[0050] It will also serve as a catalyst for the widespread use of inexpensive hydrogen gas throughout society, thereby contributing to the creation of a society that can reduce the use of fossil fuels.Furthermore, for the paper and pulp industries, it will be possible to produce hydrogen gas while manufacturing paper, paper products, and paper pulp, which could be a great opportunity to accelerate the production of environmentally friendly products.

Claims

1. A method for producing hydrogen gas, which comprises mixing biomass with a catalyst and heating the mixture to generate hydrogen gas, wherein the biomass contains chemical pulp and / or cotton.

2. 2. The method for producing hydrogen gas according to claim 1, wherein the moisture content of the biomass is 70% by weight or less.

3. 2. The method for producing hydrogen gas according to claim 1, wherein 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.

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

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

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